I got an old 3022 Hammond up local for free with a tomorrow deadline. If it doesn't go to someone who wants it, the universe will grant me an amp project. The body of the organ will make a nice guitar studio workstation. Going to place boards where the double keybeds are with rackmounts for some rack gear and the front flat surface will house a vg-99 roland and a Boss GS-10 desktop units. Place a monitor and a power head on top, change out the speaker depending on how it sounds and smile accordingly. This video is a massive help as a primer. So thanks for doing this Brad! You rock!
Got me one,but 67 year old resistors probable drifted,sent mine to Mike Moser,Frugal amps,he wired it up point to point,matchless spitfire,all new caps,and resistors,sounds amazing,volume,tone,master volume,power,and standby switch,iec cord with fuse holder,Jewell indicator light,top notch work.
This woman gave me an Hammond organ today and it's got the same amp that you just converted...man I can't wait to do mine..thanks so much for your video ....Your awesome dude...Thanks for what you do...God bless..
Tip when drilling into a chassis which is already populated with wiring and components, is to use electrical tape to form a little cup, stuck around the rear of the intended hole, to catch the swarf as it gets cut by the drill bit. Saves having to chase the bits out of the chassis before you dare to switch it on.
. I normally use a "C" clamp (or pair) to hold a piece of wood behind the target hole, it also helps keep the burs down, keeps the shavings out of the box and tells you when to stop.
At about 48:30 when you were wiring up the switch and a bit earlier when stripping the power cord, you may run into a European wiring situation and it even looks like the Hammond amp had a blue wire which should be wired to the neutral or white and a brown wire that should be wired to the hot or blacck. Also, when stripping the outer sheath (or even any bit of insulation) I like to get a really sharp knife or razor blade and cut most of the way through the insulation and then flex the wire to stress pull the insulation apart. The nic usually rips through the insulation and leaves the underlying next layer of insulation or the copper intact. If it doesn't, while the wire is bent i just nic it further and it always works. This is a great video. I just got a B20 amp with I think has 4 6V6s and no preamp. Thanx for the video. I hope that you don't think that I'm dissing you. I'm just a feral human with poor social skills.
1950`s you say? its like somebody just delivered it in a delorian time machine, your vocals were almost drowned out so you must have had the house to yourself i guess! loved it from beginning to end brad thanks ,its a beauty,
Why would anyone thumb this video down? Just get out if you are not interested. I'm guessing 4 people accidentally clicked the wrong one, or left the youtube page open, and their cat walked on their keyboard. No, there couldn't be 4 people that trollish to thumb this down. Not on the internet, right? Good job on all your videos. I watch this because in 2010 I successfully converted a Crate BV120H (Blue Voodoo) with 6L6's to a (v1)Plexi 1987-(v2)JCM800 2203 with (v3)reverb. I then bought all the components to build a new one from scratch but still haven't made the board or finished it for 7 years. I drew up schematics and still have my converted amp to reference, but before I get started i needed to refresh my knowledge on the stuff. These videos help me a lot. I may do some things differently this time. I use a 12v dc relay with 1 jack to switch channels, and a 12v dc relay to switch reverb. Of course I get a pop when I switch, so I may try the opti switch thing. They seemed hard to implement w/o losing some tone. I already use 3v dc filaments for v1 and v2, and 6 vac for the rest. I'll stick with that. So yea, thanks for the videos. They help me get my mind re-primed to start doing this again.
I usually convert these to Matchless Spitfires with good results. The tube complement and transformers make for an easy conversion. You just pull the board and repopulate it with appropriate caps and resistors. Usually the can cap works fine. There are also a lot of 18 watt Marshall schematics and layouts available for free online. The transformers are very high quality. I have put controls on either side with my conversions. My only misgivings using the side close to the tubes is the heat effecting the pots but it hasn't been a problem. The advantage besides short leads is that the tubes are closer to the outside of a combo so the heat dissipates better. Also there's less drilling into the box.
I tried running the shielding cable to the plate on an AO-35 based Carmen Ghia clone and ended up picking up a few radio stations in my signal chain as well as effectively eliminating any bass from my tone control, YMMV I guess. On another note very informative video that was invaluable in my journey to finishing my build! Thanks!
Actually at 1:08:00 it wasn't a bad resistor. You had installed capacitor C5 in backwards and it was causing excess current build up on the plate of the 6AU6 tube leading to the problem. I know this because I have watched a video where someone fixed some old electronics on youtube.
It can still happen but it's rare to see these given away now. I got a 1964 M103 for free early last year (2018) and it was seized up. All the tubes we're good though. I had to oil it up and give it a bit of elbow grease on the shaft to get it going again, but it's all there and working well. Caps need to be replaced but I've reserved all that for a full cleaning, tune up and foldback mod later.
THANK YOU for your remarks regarding saving the Hammond Organs. All of the amps you showed are out of A-100 organs, which are identical organs to the famous B-3. The AO-44 also came in the M-100 series, which are spinet organs. Generally, the M-100 series organs do not have alot of value nor alot of demand. But there are plenty of them.
My practice is to go to fuse or circuit breaker first..... When the guts of the switch fail, you will have the fuse to open, instead of an overload. In rhe days of 2 prong plugs, it did not matter, as it was random which side was hot. and with AC its always changing ‘direction’. With a grounded chassis, you probably want to have power interrupted before the first potential failure point.
. Absolutely correct. Look at the setup with the inline fuse holder. Tech opens the amp, checks the power with the switch on - nothing. Easy, blown fuse. Turns the switch off and pulls the inline fuse holder apart. The protective shell slides back and the shocks and arcs begin. Unless the disconnect switch IS the circuit protection, switch should always comes first - but doesn't, even in "professional" amps. The thought must be to protect the switch as well - I guess and in "low voltage" systems like this, may be acceptable, but not with an inline fuse holder.
There are certainly some Hammond models that are much more desirable than others, and Hammond, in addition to making some magnificent instruments, has just as certainly produced a staggering number of 'clunkers' over the years! Sadly, there's not a whole lot that can be done to salvage those. A couple of years ago, I was fortunate enough to rescue a 1953 C2, that was headed for a landfill, from a church that had been convinced that digital was the only way to go!! I donated a few hundred dollars to the church (otherwise, I really would have felt as though I was robbing them!) and explained the instrument's worth before carting it away! Shortly thereafter, I found an almost equally ridiculous deal on a basic Leslie (Model 25) which I am now in the process of converting to 2-speed and adding rotating horns. While I am all for salvaging older electronics, and converting them for use with guitar and/or bass, the magnificent power of a proper Hammond is where I have to draw the line!! Unless it's totally beyond restoration (which is seldom the case), the amp is a significant part of the Hammond-Leslie sound, and there are plenty of devoted Hammond players that would pay handsomely for many of those old amps (including the AO-29, and AO-35 reverb amp). in addition, many old Hammond and Leslie amps include parts of the Leslie switching circuit, which I can tell you is a real pain to replicate correctly...without resorting to solid state add-ons and/or expensive Trek II parts. Love your videos....I just have a major soft spot (Yes, probably in my head!) for Hammonds.
That amp is a MONSTER!!! I'd love to share my AO-29/ "64 Deluxe Reverb with you. Built by Dave Jones owner of Hook Amps, Greenwood IN. Who doesn't love UFO? You rock brother!!!!
Hi Brad, thanx for the careful explanation & builds. With reference to the feedback, a lot of guitarists do like it - why not retain it as an option? Make it switchable. I think it was Uncle Doug who made one of his projects with variable feedback. On drilling into the chassis, to make things a bit safer, sleeve the drill bit with a piece of wooden dowel leaving just enough business end sticking out to go through the metal but no further. Works a treat!
Hi What model Hammond organ used the AO35 speaker amp? I have a source who has inherited an old Organ shop by way of a real estate transaction (bought the building with a basement full of old organs) and there are 5-6 Hammond’s in the bunch
At 26:45: You just just broke it, as near as I can tell! I have a 62 Baldwin that I want to repurpose all the things inside from... once I figure out which end to hold the soldering iron at. This is great, thanks so much for sharing it!!!
I should keep it to myself but they are rare enough....old vintage Garnetts are sweet too. Got a couple of those Canadian jems as well. Talked to Mr. Garnett quite a few times before he passed.
Lol, I always just intuitively (since I don't actually know shit) dealt with shrink tubing precisely the same way you did it at about 53:00. Works like a charm.
A Zobel network is really pretty simple, it is just the inverse of the speakers inductance due to capacitive reactance, I’m not sure why you’d really want that here. They are used when you have a 2 or 3 way speaker design to present the passive crossover with a constant impeadance rather than an inductive rise as frequency goes higher, this makes designing crossovers easier, that’s pretty much what’s its used for in practice... For instance, a 4 ohm 12 inch speaker might be 3.8ohms at DC but at 500hz it might be 78ohms, this circuit would make the impeadance more flat, so you’d have 3.8ohms at DC and 5 ohms at 500hz, so this would help the amp see the speaker as more resistor like than inductor like, it should not have all that much effect on tone if it’s designed correctly. There is no just putting a capacitor and resistor in the circuit and seeing what it sounds like, this network needs to be specifically designed for the exact speaker it’ll be used on... Wikipedia doesn’t have very good information in this case, this would not be the best method to tame a misbehaving amplifier that’s oscillating, although it would probably work. It might have been used for that 80 years ago, but obviously electronics has changed just a little bit since then.
".....and if your amp is a monster...." It sounds incredible! Thanks for this, and the other videos that I've been feeding the sweet tooth of my brain the past few days!
You know why your channel is the best and so do I. I am an electronics engineer/technician and love what you do in these videos. Now I am a subscriber and using youtube more and liking the videos! Gonna be having fun with amps when I get some dough going. Thanks for the killer channel!
There is an amp that has been in my dad's attic for as long as I can remember. With it, is a metal plate with oiling instructions and indicates it is a Hammond model M amplifier, serial number 11836, 115 volts AC, 60 cycles, 93 console watts. There is one larger transformer that has no corrosion, as well as a smaller one, also without corrosion, that has AO-20936-0. The tubes look okay, and are as follows: 5U4, 6BA6, 6V6, 6V6, 6SC7, 6J7, 6J5, & 6SJ7. On the "front" are various screws, that look like wires have been attached, as well as a couple of what looks like RCA inputs. The best I could read with my old man eyes: "Pedal Cutoff" "Key SW" "Decay SW" "Sus SW" "Pedal In" "Voice Coil" "Ped" "Att-Key" "VIB"(?) The RCA looking inputs have (best I can tell) "Radio Phono" & "Spec Input" So……would this make a good guitar amplifier? I know absolutely nothing about electronics, but do play guitar, and love the different colors and temperatures of tones that tubes can produce. I am not asking how to do what needs to be done, because I am sure I will be finding someone to be with me every step I take…..I've just not seen anything other than amplifiers from M3's, M2's, or M100's anywhere. I DID, however, find the schematics, block diagrams, wiring for the organ itself….but what is the amp called? AO-20936-0??? Thanks, and sorry for asking so much ! Ke & Ri
Can you help me out with an issue I'm having with this amp? I'm not getting plate voltages on the first 12ax7 tube. On the second one I'm getting good plate voltage. I haven't changed out the coupling caps, they are original. I did change the main filter caps. Any thing I'm missing?? Thanks
GUITAR PLAYER 40 YEARS, ORGAN PLAYER 22 YEARS NOW. Ugh, makes me cringe somewhat seeing, the GREAT AO-35 3-SPRING NECKLACE SPRING REVERB AMP BEING USED TO MAKE GUITAR AMPS...but shouldn't we be seeing Necklace springs on Ebay more? If you want a hoot, read the HAMMOND ORGAN HR40 TONE CABINET SERVICE TECHNICIANS 'TECHNICAL BULLETIN' " REPLACING OIL FILLED REVERB SPRING WITH NEW TANK REVERB, INSTRUCTIONS FOR PREAMP [built by tech infield using a transistor...]. Note the late 40's- 5?'s HR40 TONE CAB [ which I play through in my video below] HAS TWO AMPS, ONE GIANT CHASSIS, 8 6V6'S, MULTIPLE 6SN7'S,6SL7'S, 9- 8"'ish speakers @ 1-2 ohm total driven!, and 2 12" pm speakers pointed straight. ...at any rate,the tech notice instructs, " carefully remove HAMMOND oil reverb assembly* wrap in newspaper, and dispose of it". *[forget 'technical name, but it was the 1st reverb, as was designed by reverb inventor- LAURENS HAMMOND] Since the TANK REVERB also was the successor to 3-SPRING NECKLACE REVERB, makes you wonder how many of those were disposed of. THE NECKLACE REVERBS ARE THE BEST EVER SPRING REVERB...3 springs for L/H/& W! I have the 1952' HAMMOND HR40,but also an ER20 'DECORATIVE [ WHICH BTW, YOU CAN SIMPLY 'DRIVE THE 'SPKR IN' OF THE AO-35, AO-44 to April'ish 62', and AO-44* .IN WITH AN EXISTING SMALL SINGLE TUBE 6BQ5/EL84 OR 6V6 AMPS SPKR-OUT. I have a HAMMOND A100 from APRIL 1962' [100% ORIGINAL] wIth the AO-44 TANK REVERB DRIVE THE POST- APRIL 1962' AO-44 is w/ same AO-44 GUTS, BUT THEY USED ONE TRANSISTOR AS WELL , in place of 1/2 12A?7. PLEASE PLEASE PLEASE, SAVE THE VERY VERY INCREDIBLE *WURLITZER* *1953*'*-* *1963'* *ELECTROSTATIC* *CONTINUOUS* *FREE*REED *ORGAN* , AND *THE* *>>ONLY
Love your videos. Sometimes it's helpful to have an octal tube base loaded with a couple of diodes to emulate the rectifier tube for when you're variacing the device up. That way you don't have to be concerned with the filament voltage in that tube. Of course use only for testing at lower AC input as the diodes will pass considerably more voltage out at full AC than the tube rect and possibly over voltage the filter caps. Great work.
i was following everything until you had the holes drilled and the volume & tone pots mounted. so the volume will be a 100k logarithmic taper but what will the tone pot be a logarithmic or a linear ?
+The Guitologist ok well i thank you again my friend. when i get done with this ao 35 amp, i will be making a youtube video of it being used & giving out that sweet vintage tube sound that we all love to hear an feel
Great video. Thanks for sharing this. I had a Mitchell 15 watt tube amp 6w6 changed to 6v6 came out of a record player early '50s converted into a guitar amp. GREAT sounding tone
How do you upgrade the memory in those amps? Say I wanted to go from 2Gb to 8Gb where do I plug in the SCSI cable? Also how do I make it pay mp3's off an SD card? The SD card has more wires then the input on the amp. Can you just tie the extra wires together?
My 1st tube guitar amp was a repurposed mono all tube reel to reel player , my 1st guitar amp was a ss 6 inch combo with only v and t controls 20 dollars then ! being poor you got to be creative as a teen ! that sucked , it was in the late 70's -think cat scratch fever was out when i bought that ! anyway conversion was simple , i removed reel to reel mech , and just plunged into the aux or mic input ! , the mic input had distortion gain , think sunshine of your love sound ! it had a 3 way speaker and was quite loud , wish i kept it , wish i didn't ruin the reel to reel , just got tired of repairing the belt drive lol , also when we threw out our Magnavox console color tv all tube ! i should have saved the amp section ! it had 2 15" loud speakers and 2 12 inch horns ! i kept the speakers only with the crossovers ! that was my loud tube guitar amp , using the aux input ! what a sound its radio and turn table had , like at a live concert !
Sorry for being late to the party, but I couldn't help but to pass along something as a Hammond player. ( I own a B-3, a C-2, and an H-100). I wouldn't "fret" over the usage of these amps for projects, since the wimpy 35 (at best) watts that these babies output can barely be heard in a modern band setting without being mic'd or a DI installed and piped directly into the PA. Most players I know, including myself, have replaced the AO35 with a modern amplifier of at least 100 watts. Not to mention that many old Hammond amps like the AO71 used GZ34/5AR4 rectifier tubes, which you likely know, since some Gibson tube amps use them, that a USA NOS tube will cost you $200, $300 for a vintage NOS Mullard, and $400 for an Amperex Bugle Boy tube! I wouldn't worry about these little amps being used for projects! I have at least 10 of these sitting around waiting to become something useful!!
Although I wouldn't mind owning a SMD-type heat gun. Or better yet, a hot-air SMD rework station, like the DIC Denon SD-2000 or SD-3000. I'm so cheap that I use a 150 Watt spotlight bulb to activate heat-shrink tubing. It works rather well and almost won't damage the tubing, unless left too close, for too long. But, it does take considerable time to do so.
Sick amp, really does sound good. And sick UFO! It has that nice singing tone to leads with some attack. Not at all harsh despite all the gain and highs. And pleasant crunch. This as two channel amp with cleans having some headroom would be perfect. Some of the characteristics remind me of my Lee Jackson preamp, just with less harsh treble range. I have a feeling it shares some design in the first stages with these kind of small amps that you do, something that does the spanky attack even on drive sounds. I've heard its circuit is following old Fender designs, just with added gain stages. Rock on! These amp servicing/modding videos have been my binge watch during this lockdown time, can't get enough of them. And trying to suck as much info from them as possible. So far gotten great practical bits about trouble shooting, behavior and fixes to common problems in amps. I feel like someone would be able to build a decent amp just by watching a lot of your channel. Perfect nerding out and ruthless humor. And killer guitar playing of course. Anyway, just wanted to say thanks for this content, the info you share feels reliable contrary to how you often have to second guess a lot of stuff you see on youtube. And it's delightful to see every now and then how you and your kid smile to each other.
John Hammond invented the tube Amp. If your ever in the Salem Mass. area go check out Hammond Castle. Really COOL place. And they have a couple of his first amps on display. You won’t believe how big they are. Great video although quite long. Lol 😎🎸🎶✌️
The fuse should always be the first thing a power supply hits when it gets to a circuit. The reason is pretty simple. In the event of a fault that blows the fuse, the power is isolated to where it entered the circuit, thus the whole circuit is protected.
So I've got one that I've just finished my initial mods to which follow many of the suggestions that have been mentioned here. I'm amazed at how quiet the amp is even though the only new parts are in the tone circuit and input. I've also completely removed the NFBL and the zobel network (this was done for me when I powered on the amp and the resistor in the zobel network burned up). The issue that I've come across is that at about 3-5 on the volume, I get some high pitch squeal. Above that the squeal goes away but the volume is substantially lower and there are a lot of what I assume are odd order harmonics in the distortion (to be honest I'm having a hard time finding a video demonstrating odd order harmonics to be able to confirm my suspicion. The controls are in the same location as the CG and I ran across another thread a while ago (of course I can't find it now) that mentioned having the controls that close to the OT, can cause some interference and that if that's where you're going to mount it, that you need to have it shielded. Anther possible cause? I have 2 new, matched output tubes coming as I think I've ruled the pre-amp tubes out through swapping out with some that I had on hand which I knew were good. Open to any feedback. P.S. amp sounds great at the volume below where I experience the squealing.
I have a few of these I've done. My favorite conversion is using AO-35 and making a Matchless Spitfire. I usually install them in old dynamite crates. The layouts and schematics are readily available online
A fine scotchbrite pad is probably a safer thing to use for rust removal in an amp. Only takes one steel wool fibre in the wrong place to cause problems.
how you do things works,so its good enough for the people who know you are an excellent amp builder.that amp sounds absolutely killer and has wicked dynamics and you have some serious chops my friend.if the amp fixing thing ever stops you could be a gigging monster
The demo was over @ about 1:36:15. Past that it was clear how good the amp sounded by the look on your face/playing lol. You were just having fun after that hahahahaha. Nice work man!
I greatly appreciate the help I'm starting my build this weekend and have been thoroughly studying your video. I absolutely love the outcome you got from this setup. Thanks again I always look foward and enjoy all of your vidoes!
@1:11:36.........Brings back memories of my childhood....when the stomping was rendered useless, the main power fuse(for the basement) was extremely effective...lolol
Hey Brad. I like the videos. Iam an Uncle Doug fan as well. I was wondering; those ceramic disc capacitors you replaced with orange drops.. is it microfarads. in the AO35 ? I only have a basic volt meter and. cant test the capacitors. Thanks.
Wait, at 52:00 I must have have heard wrong. Yeah, I sorta did hear wrong. A 12AX7 plate is around +210 volts above ground so don't forget and wire the other end of the coax to the input jack end to ground. I've heard of only grounding one end and float the other end so that you don't have ground loops. I'm trying to figure how that works. The thing that I'm coming up with is the DC doesn't flow but you get a counterpoised (180 degree out of phase) signal on the sheild. Do you know what gives here?
It’s funny mentioning Dr Z in this. What I thought seeing this video was about the fact I’ve been looking for a organ or projector or other similar amp with the right size transformers to build a Route 66 clone. They’re a stupid simple circuit but I love the sound they have.
Hello, I see you have several Hammond preamps, I was wondering if you have any transformers from the percussion amp section left over. Since you won’t be using it for the guitar amp convention. I’m looking for one for my organ. Thanx
I mounted the board and brackets on additional brackets, so it is horizontal. Much easier to experiment on. The original circuit has plenty of gain once the input components are changed to values suitable for guitar. I don't think it really needs much tweaking beyond that.
Good grief! That is righteous, man! Came here to get information on re-capping a AO-43 (eBay) to double amp great grandmothers M103 (and get practice before re-cap the M103), stay in for all the tips, and settle in for the playing, well done on both build and playing. 41:40 Firstly, a file is to be used forward, dragging back damages the teeth. Secondly, they also make a hole reamer that be faster and easier. Hope this helps. 1:17:10 With more than one ground point, how are you avoiding ground loops? Thanks.
Great video sir! I have an AO 35 amp and this will be my first venture into building my own home brew amp.. I am still learning about how tube amps work, but I've been trying to educate myself through great videos like yours as well as Uncle Dougs. Could you by chance put up a link of your final schematic? I've seen others, but I believe you've done things slightly different than the others, and to be honest, I like the sound of yours the best out of all the ones I've heard. Thanks for helping the way you do!
Removed the Boucherot from an Ao-44 and it did seem to make the tone a bit less “grey” to my ears,at least. I haven’t added a 12ax7 to it so it’s fairly stock other than a bright cap of an unusual value since I experimented with what I had on hand. Always wondered what that part of the circuit was supposed to do. Completely gutted the Ao 35 I have besides the transformers and tubes.. Prolly do the 18 watt thing. Watching this to see where u go with it. :)
Hi Brad...I am attempting my first push pull build. I have a beautiful pair of Tung-Sol 6550's and I read on the internet that a 5Y3 would choke such a build, apparently they thought that little rectifier can't keep up with the power of those 6550 tubes. I have been looking at Rob Robinette's pages and decided to build a 5F6 Bassman with these mighty tubes and would appreciate any advice you might share. The original amp was a Stromberg Carlson P.A. head that used this very same rectifier and as a guitarist, I want to build something useful that sounds good. There are a ton of mods that Rob Robinette uses on his builds and I'm sure I will implement some of them. I have built a "Champ' clone and it turned out great but this build with the phase inverter circuit and a good tone network is lots more than that little Champ circuit was. As always, you clips are much enjoyed and appreciated, as are Uncle Doug's.
The reason converting something like this is preferable to a scratch build is you often get the transformers and chassis and tubes cheaper this way. If you’re stuck on 6550, look into building a 2204 Marshall perhaps. You could use Bassman transformers.
Check with churches. That's where I got mine. Once they upgrade to multi channel boards and key boards, they just unplug them and stick them somewhere. You can sometime get awesome tone cabinets/speakers with them as well.
thanks for this- Great job and so helpful- I'm struggling with some the very issues you address and will now try your mods!Only request is for a post of your final schematic.
roger that- I tried a screen capture but the resolution isn't too great- just thinking a file of that schematic would be so helpful- you did a great job simplifying the AO35 and showing your final layout...
AH! How silly of me not to think of that. Of course it would be a PIA to see a screenshot and print it out. Lemme see if I still have the schematic lying around...
EPIC! Great work...I'm a fairly intelligent person but I can't even wrap my head around the world of electronics/schematics and the level of work you do. The amp sounds fantastic. You should put together an online class to teach amp repair. Mojotone occasionally has 2-day workshops at their headquarters where you build your own amp.
I have a Hammond L-100 or thereabouts, that has needed a starter motor for about 30 years. I have a used motor and have tried to give away Hammond and engine for free, to churches, but no one wants it, here in 2020 ... Had an old Leslie too, but termites got into it ... Battin' a thousand, here ...
I really love it when you have a good build and get all fired up... I'm like happy for you. Wish I wuz there so I could test a couple of my guitars... I know I'd be trippin' keep 'em coming! cheers
Amazing tutorial and video! The guitar playing at the end was also great. I garbage picked a AO-14 amp out of an M-2 organ in my neighborhood and your results with the tone and sound are inspiring. I see many similarities between the AO-35 amp and mine; however, the AO-14 has several more tubes and is physically larger. Just wondering if anyone has had success with that model amp.
+Mike Choffin You should be able to make that amp into a monster with similar qualities as this AO-35. Of course, you could make it into whatever sort of amp you like. The Hammond transformers are TOPS! Best transformers ever made, probably. Mercury Magnetics have got nothing on these old Hammonds, I assure you. You have probably the best starting platform you could ask for. Some thoughtful and creative designing, and you'll have a great amp, I'm sure of it.
+The Guitologist I may have spoke too soon. The schematic for the T-4 power transformer shows three output voltages from the secondary windings. 5- , 6.3- and 340-volts. I don't get power from any of the secondary taps. I'd guess that the main power transformer is dead. The footprint of the model you converted is much smaller than the AO-14, nearly 22" long. I may just wait to see if I can find one like you converted.
+Finom1 'm not sure. I new to this and learning as I go. Like I stated above, I garbage -picked the amp section and speaker an M-2 organ that someone in my neighborhood was throwing-out. From what I can tell reading on the internet, both amps will produce very powerful sound output. Looks like a great project.
Amazing video! On one of my computers I use a Mullard Altobass / Stereo 44 amp (EF86 - EL84) amp from 1967. Apart from the valves (its on it's third set) everything is original and it does make some popping sounds within the first minute of starting up but works fine, sounds stunning with anything from classical to dubstep. I've got a Trix push-pull EL84 amp in the garage I've been meaning to rebuild for decades - might get on with it now! :o)
This is GREAT! Thank you. I just re-capped mine and hope to wire up the pots soon. One question though, I have a reverb unit I salvaged from a marshal amp. How would I wire in a "effects loop" with a Pot to control it?
That's really outside the scope of this video, but you might might useful information on this forum: el34world.com/Forum/index.php?topic=10208.0 Thanks for watching and good luck!
Yeah, i know I just figured you'd be the guy to ask about it. Maybe not an effects loop though. Most amps just have a Pot for reverb. I figured that would be easy enough to insert near the tone stack? I'm really a noob when it comes to understanding this stuff but I seem to be able to follow directions well! This will make my second tube project. The first was recapping a Bogen DB230 stereo. (sounds great!)
Oh, and is there any reason I shouldn't mount this amp upside down in the top of a custom built cabinet (tubes in the rear plugging up into the box) That's kinda been my vision for this project but I've only seen guys mount them in the bottom of the cabs.
Several quick questions please. 1. What did you do with the green wire you clipped from the terminal strip at the beginning of the video? 2. Where is the tone stack wired in at? 3. Where is the lamp wired in at? My project is almost complete and I need you assistance.
Is it possible to convert this amp for guitar and keep the reverb? Maybe adding an additional tube to drive the tank? I’d love to get some feedback on the best way to do that.
how hard would it be to use an EF86 as the first preamp tube? I have an old AO 35 that's been lying around the shop for years. thanks for posting this. Uncle Doug demoed one but didn't get into the details of the conversion like you did. great job.
+zendixie Thanks for watching and commenting! An EF86, being a single pentode, you may actually end up losing some gain and volume overall because you're trading the first two stages of triodes for one pentode. I'm sure we could look at the datasheets and do the calculations and figure out exactly how much you'd lose, but I'm guessing it would be significant, and the end result would be very different than what I ended up with here. If you're looking for a far cheaper alternative to the EF86 to have a pentode up front, you can also check out the 6GH8A. Similar to a 7199. It has a triode AND a pentode in the same envelope. You can retain the two gain stage architecture without adding another tube socket.
+The Guitologist I'm trying to find a way to get a cheaper Winfield Cyclone. Also the Super 17 amps started as AO35 amps and I think some of those used an ef86 , maybe followed by another 12ax7. Matchless DC 30s use the ef86 as well. the gain may be less but to me the tone makes up for it.
I got an old 3022 Hammond up local for free with a tomorrow deadline. If it doesn't go to someone who wants it, the universe will grant me an amp project. The body of the organ will make a nice guitar studio workstation. Going to place boards where the double keybeds are with rackmounts for some rack gear and the front flat surface will house a vg-99 roland and a Boss GS-10 desktop units. Place a monitor and a power head on top, change out the speaker depending on how it sounds and smile accordingly. This video is a massive help as a primer. So thanks for doing this Brad! You rock!
Got me one,but 67 year old resistors probable drifted,sent mine to Mike Moser,Frugal amps,he wired it up point to point,matchless spitfire,all new caps,and resistors,sounds amazing,volume,tone,master volume,power,and standby switch,iec cord with fuse holder,Jewell indicator light,top notch work.
This woman gave me an Hammond organ today and it's got the same amp that you just converted...man I can't wait to do mine..thanks so much for your video ....Your awesome dude...Thanks for what you do...God bless..
Tip when drilling into a chassis which is already populated with wiring and components, is to use electrical tape to form a little cup, stuck around the rear of the intended hole, to catch the swarf as it gets cut by the drill bit. Saves having to chase the bits out of the chassis before you dare to switch it on.
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I normally use a "C" clamp (or pair) to hold a piece of wood behind the target hole, it also helps keep the burs down, keeps the shavings out of the box and tells you when to stop.
Yeah. I was thinking all those shavings ain’t a good thing. Good to know these tips.
Yep, all good ideas. I use that good blue masking tape & rags to keep the flingy bits in.
At about 48:30 when you were wiring up the switch and a bit earlier when stripping the power cord, you may run into a European wiring situation and it even looks like the Hammond amp had a blue wire which should be wired to the neutral or white and a brown wire that should be wired to the hot or blacck.
Also, when stripping the outer sheath (or even any bit of insulation) I like to get a really sharp knife or razor blade and cut most of the way through the insulation and then flex the wire to stress pull the insulation apart.
The nic usually rips through the insulation and leaves the underlying next layer of insulation or the copper intact. If it doesn't, while the wire is bent i just nic it further and it always works.
This is a great video. I just got a B20 amp with I think has 4 6V6s and no preamp. Thanx for the video. I hope that you don't think that I'm dissing you.
I'm just a feral human with poor social skills.
Wow a monster amp indeed! Sounds a lot like a Magnatone. A couple of those with a stereo tremolo effect and Billy Gibbons might come knockin! :)
1950`s you say? its like somebody just delivered it in a
delorian time machine, your vocals were almost drowned
out so you must have had the house to yourself i guess!
loved it from beginning to end brad thanks ,its a beauty,
Why would anyone thumb this video down? Just get out if you are not interested. I'm guessing 4 people accidentally clicked the wrong one, or left the youtube page open, and their cat walked on their keyboard. No, there couldn't be 4 people that trollish to thumb this down. Not on the internet, right?
Good job on all your videos.
I watch this because in 2010 I successfully converted a Crate BV120H (Blue Voodoo) with 6L6's to a (v1)Plexi 1987-(v2)JCM800 2203 with (v3)reverb.
I then bought all the components to build a new one from scratch but still haven't made the board or finished it for 7 years. I drew up schematics and still have my converted amp to reference, but before I get started i needed to refresh my knowledge on the stuff.
These videos help me a lot.
I may do some things differently this time. I use a 12v dc relay with 1 jack to switch channels, and a 12v dc relay to switch reverb. Of course I get a pop when I switch, so I may try the opti switch thing. They seemed hard to implement w/o losing some tone.
I already use 3v dc filaments for v1 and v2, and 6 vac for the rest. I'll stick with that.
So yea, thanks for the videos. They help me get my mind re-primed to start doing this again.
I usually convert these to Matchless Spitfires with good results. The tube complement and transformers make for an easy conversion. You just pull the board and repopulate it with appropriate caps and resistors. Usually the can cap works fine. There are also a lot of 18 watt Marshall schematics and layouts available for free online. The transformers are very high quality. I have put controls on either side with my conversions. My only misgivings using the side close to the tubes is the heat effecting the pots but it hasn't been a problem. The advantage besides short leads is that the tubes are closer to the outside of a combo so the heat dissipates better. Also there's less drilling into the box.
I tried running the shielding cable to the plate on an AO-35 based Carmen Ghia clone and ended up picking up a few radio stations in my signal chain as well as effectively eliminating any bass from my tone control, YMMV I guess. On another note very informative video that was invaluable in my journey to finishing my build! Thanks!
Actually at 1:08:00 it wasn't a bad resistor. You had installed capacitor C5 in backwards and it was causing excess current build up on the plate of the 6AU6 tube leading to the problem. I know this because I have watched a video where someone fixed some old electronics on youtube.
It can still happen but it's rare to see these given away now. I got a 1964 M103 for free early last year (2018) and it was seized up. All the tubes we're good though.
I had to oil it up and give it a bit of elbow grease on the shaft to get it going again, but it's all there and working well. Caps need to be replaced but I've reserved all that for a full cleaning, tune up and foldback mod later.
THANK YOU for your remarks regarding saving the Hammond Organs. All of the amps you showed are out of A-100 organs, which are identical organs to the famous B-3.
The AO-44 also came in the M-100 series, which are spinet organs. Generally, the M-100 series organs do not have alot of value nor alot of demand. But there are plenty of them.
My practice is to go to fuse or circuit breaker first..... When the guts of the switch fail, you will have the fuse to open, instead of an overload. In rhe days of 2 prong plugs, it did not matter, as it was random which side was hot. and with AC its always changing ‘direction’. With a grounded chassis, you probably want to have power interrupted before the first potential failure point.
.
Absolutely correct. Look at the setup with the inline fuse holder.
Tech opens the amp, checks the power with the switch on - nothing. Easy, blown fuse. Turns the switch off and pulls the inline fuse holder apart. The protective shell slides back and the shocks and arcs begin.
Unless the disconnect switch IS the circuit protection, switch should always comes first - but doesn't, even in "professional" amps. The thought must be to protect the switch as well - I guess and in "low voltage" systems like this, may be acceptable, but not with an inline fuse holder.
There are certainly some Hammond models that are much more desirable than others, and Hammond, in addition to making some magnificent instruments, has just as certainly produced a staggering number of 'clunkers' over the years! Sadly, there's not a whole lot that can be done to salvage those.
A couple of years ago, I was fortunate enough to rescue a 1953 C2, that was headed for a landfill, from a church that had been convinced that digital was the only way to go!! I donated a few hundred dollars to the church (otherwise, I really would have felt as though I was robbing them!) and explained the instrument's worth before carting it away! Shortly thereafter, I found an almost equally ridiculous deal on a basic Leslie (Model 25) which I am now in the process of converting to 2-speed and adding rotating horns.
While I am all for salvaging older electronics, and converting them for use with guitar and/or bass, the magnificent power of a proper Hammond is where I have to draw the line!! Unless it's totally beyond restoration (which is seldom the case), the amp is a significant part of the Hammond-Leslie sound, and there are plenty of devoted Hammond players that would pay handsomely for many of those old amps (including the AO-29, and AO-35 reverb amp). in addition, many old Hammond and Leslie amps include parts of the Leslie switching circuit, which I can tell you is a real pain to replicate correctly...without resorting to solid state add-ons and/or expensive Trek II parts.
Love your videos....I just have a major soft spot (Yes, probably in my head!) for Hammonds.
Blown away by the amp build demo. I got one on the way and am so pumped to get going. Hope to get similar end results.
+Ross H. Good luck and be sure to observe basic safety.
That amp is a MONSTER!!! I'd love to share my AO-29/ "64 Deluxe Reverb with you. Built by Dave Jones owner of Hook Amps, Greenwood IN. Who doesn't love UFO? You rock brother!!!!
Hi Brad, thanx for the careful explanation & builds. With reference to the feedback, a lot of guitarists do like it - why not retain it as an option? Make it switchable. I think it was Uncle Doug who made one of his projects with variable feedback. On drilling into the chassis, to make things a bit safer, sleeve the drill bit with a piece of wooden dowel leaving just enough business end sticking out to go through the metal but no further. Works a treat!
Hi
What model Hammond organ used the AO35 speaker amp?
I have a source who has inherited an old Organ shop by way of a real estate transaction (bought the building with a basement full of old organs) and there are 5-6 Hammond’s in the bunch
At 26:45: You just just broke it, as near as I can tell! I have a 62 Baldwin that I want to repurpose all the things inside from... once I figure out which end to hold the soldering iron at. This is great, thanks so much for sharing it!!!
I should keep it to myself but they are rare enough....old vintage Garnetts are sweet too. Got a couple of those Canadian jems as well. Talked to Mr. Garnett quite a few times before he passed.
Lol, I always just intuitively (since I don't actually know shit) dealt with shrink tubing precisely the same way you did it at about 53:00. Works like a charm.
A Zobel network is really pretty simple, it is just the inverse of the speakers inductance due to capacitive reactance, I’m not sure why you’d really want that here. They are used when you have a 2 or 3 way speaker design to present the passive crossover with a constant impeadance rather than an inductive rise as frequency goes higher, this makes designing crossovers easier, that’s pretty much what’s its used for in practice... For instance, a 4 ohm 12 inch speaker might be 3.8ohms at DC but at 500hz it might be 78ohms, this circuit would make the impeadance more flat, so you’d have 3.8ohms at DC and 5 ohms at 500hz, so this would help the amp see the speaker as more resistor like than inductor like, it should not have all that much effect on tone if it’s designed correctly. There is no just putting a capacitor and resistor in the circuit and seeing what it sounds like, this network needs to be specifically designed for the exact speaker it’ll be used on... Wikipedia doesn’t have very good information in this case, this would not be the best method to tame a misbehaving amplifier that’s oscillating, although it would probably work. It might have been used for that 80 years ago, but obviously electronics has changed just a little bit since then.
I wish there was a button to (EXTRA)- (double) like the videos that one whats more than once.You ROCK Brad!
".....and if your amp is a monster...."
It sounds incredible! Thanks for this, and the other videos that I've been feeding the sweet tooth of my brain the past few days!
Oh my goodness ! That thing sounds a bit like a Dumble ! Yeah I said it ........! That thing has a million dollar tone my friend ! Great job !
You know why your channel is the best and so do I. I am an electronics engineer/technician and love what you do in these videos. Now I am a subscriber and using youtube more and liking the videos! Gonna be having fun with amps when I get some dough going. Thanks for the killer channel!
There is an amp that has been in my dad's attic for as long as I can remember. With it, is a metal plate with oiling instructions and indicates it is a Hammond model M amplifier, serial number 11836, 115 volts AC, 60 cycles, 93 console watts. There is one larger transformer that has no corrosion, as well as a smaller one, also without corrosion, that has AO-20936-0. The tubes look okay, and are as follows: 5U4, 6BA6, 6V6, 6V6, 6SC7, 6J7, 6J5, & 6SJ7. On the "front" are various screws, that look like wires have been attached, as well as a couple of what looks like RCA inputs. The best I could read with my old man eyes: "Pedal Cutoff" "Key SW" "Decay SW" "Sus SW" "Pedal In" "Voice Coil" "Ped" "Att-Key" "VIB"(?) The RCA looking inputs have (best I can tell) "Radio Phono" & "Spec Input"
So……would this make a good guitar amplifier? I know absolutely nothing about electronics, but do play guitar, and love the different colors and temperatures of tones that tubes can produce. I am not asking how to do what needs to be done, because I am sure I will be finding someone to be with me every step I take…..I've just not seen anything other than amplifiers from M3's, M2's, or M100's anywhere. I DID, however, find the schematics, block diagrams, wiring for the organ itself….but what is the amp called? AO-20936-0???
Thanks, and sorry for asking so much !
Ke & Ri
Thanx Brad, I still miss my M3. I dont play keys well but I loved playin' that old Hammond trying.
Enjoyed the video, well done. I've probably done around 75 of these conversions.
Can you help me out with an issue I'm having with this amp? I'm not getting plate voltages on the first 12ax7 tube. On the second one I'm getting good plate voltage. I haven't changed out the coupling caps, they are original. I did change the main filter caps. Any thing I'm missing?? Thanks
"Take your time with these kind of things, you don't want to make a mess. Eye protection is recommended."
That's what she said.
Zobel circuit used to balance loud speakers with different sound pressure level outputs by attenuation of the higher SPL speakers signal.
Amazing sound, well-worth the time and effort you put into it, Brad.
GUITAR PLAYER 40 YEARS, ORGAN PLAYER 22 YEARS NOW. Ugh, makes me cringe somewhat seeing, the GREAT AO-35 3-SPRING NECKLACE SPRING REVERB AMP BEING USED TO MAKE GUITAR AMPS...but shouldn't we be seeing Necklace springs on Ebay more?
If you want a hoot, read the HAMMOND ORGAN HR40 TONE CABINET SERVICE TECHNICIANS 'TECHNICAL BULLETIN' " REPLACING OIL FILLED REVERB SPRING WITH NEW TANK REVERB, INSTRUCTIONS FOR PREAMP [built by tech infield using a transistor...]. Note the late 40's- 5?'s HR40 TONE CAB [ which I play through in my video below] HAS TWO AMPS, ONE GIANT CHASSIS, 8 6V6'S, MULTIPLE 6SN7'S,6SL7'S, 9- 8"'ish speakers @ 1-2 ohm total driven!, and 2 12" pm speakers pointed straight.
...at any rate,the tech notice instructs,
" carefully remove HAMMOND oil reverb assembly* wrap in newspaper, and dispose of it".
*[forget 'technical name, but it was the 1st reverb, as was designed by reverb inventor- LAURENS HAMMOND]
Since the TANK REVERB also was the successor to 3-SPRING NECKLACE REVERB, makes you wonder how many of those were disposed of.
THE NECKLACE REVERBS ARE THE BEST EVER SPRING REVERB...3 springs for L/H/& W!
I have the 1952' HAMMOND HR40,but also an ER20 'DECORATIVE
[ WHICH BTW, YOU CAN SIMPLY 'DRIVE THE 'SPKR IN' OF THE AO-35, AO-44 to April'ish 62', and AO-44* .IN WITH AN EXISTING SMALL SINGLE TUBE 6BQ5/EL84 OR 6V6 AMPS SPKR-OUT.
I have a HAMMOND A100 from APRIL 1962' [100% ORIGINAL] wIth the AO-44 TANK REVERB DRIVE
THE POST- APRIL 1962' AO-44 is w/ same AO-44 GUTS, BUT THEY USED ONE TRANSISTOR AS WELL , in place of 1/2 12A?7.
PLEASE PLEASE PLEASE, SAVE THE VERY VERY INCREDIBLE *WURLITZER* *1953*'*-* *1963'* *ELECTROSTATIC* *CONTINUOUS* *FREE*REED *ORGAN* , AND *THE* *>>ONLY
@@keithschneidly3922 No, it's all Greek.
That thing is righteous. Nice work Brad
Love your videos.
Sometimes it's helpful to have an octal tube base loaded with a couple of diodes to emulate the rectifier tube for when you're variacing the device up. That way you don't have to be concerned with the filament voltage in that tube. Of course use only for testing at lower AC input as the diodes will pass considerably more voltage out at full AC than the tube rect and possibly over voltage the filter caps.
Great work.
I built a whole amp on my channel from stat to finish as and it took so many hours. I enjoy your videos. Wish it was longer.
i was following everything until you had the holes drilled and the volume & tone pots mounted. so the volume will be a 100k logarithmic taper but what will the tone pot be a logarithmic or a linear ?
Either will work. Linear might work a little better on tone.
+The Guitologist ok well i thank you again my friend. when i get done with this ao 35 amp, i will be making a youtube video of it being used & giving out that sweet vintage tube sound that we all love to hear an feel
Killer! Please provide us a link in the comments here! I'd love to hear it. I'm sure my viewers would too.
Great video. Thanks for sharing this. I had a Mitchell 15 watt tube amp 6w6 changed to 6v6 came out of a record player early '50s converted into a guitar amp. GREAT sounding tone
Nice Ultra GS! I picked one of these up earlier this year, and I love it.
How do you upgrade the memory in those amps? Say I wanted to go from 2Gb to 8Gb where do I plug in the SCSI cable? Also how do I make it pay mp3's off an SD card? The SD card has more wires then the input on the amp. Can you just tie the extra wires together?
Although this has several PCI expansion slots, they are unfortunately not backwards compatible with Windows XP Home Edition.
@@TheGuitologist pahahahaaahaha 🤣😆😂 ..goddamnit Brad *✔*
My 1st tube guitar amp was a repurposed mono all tube reel to reel player , my 1st guitar amp was a ss 6 inch combo with only v and t controls 20 dollars then ! being poor you got to be creative as a teen ! that sucked , it was in the late 70's -think cat scratch fever was out when i bought that ! anyway conversion was simple , i removed reel to reel mech , and just plunged into the aux or mic input ! , the mic input had distortion gain , think sunshine of your love sound ! it had a 3 way speaker and was quite loud , wish i kept it , wish i didn't ruin the reel to reel , just got tired of repairing the belt drive lol , also when we threw out our Magnavox console color tv all tube ! i should have saved the amp section ! it had 2 15" loud speakers and 2 12 inch horns ! i kept the speakers only with the crossovers ! that was my loud tube guitar amp , using the aux input ! what a sound its radio and turn table had , like at a live concert !
There are tools for striping cable outer insulation, cheap and they make the work one twist of the wrist. Also no cut thumbs :D
This is a monster, Brad! i like it very much my friend, great job.
At 41:54, you could use a bigger drill bit just to clean the edges of the hole. Just a suggestion.
Sorry for being late to the party, but I couldn't help but to pass along something as a Hammond player. ( I own a B-3, a C-2, and an H-100). I wouldn't "fret" over the usage of these amps for projects, since the wimpy 35 (at best) watts that these babies output can barely be heard in a modern band setting without being mic'd or a DI installed and piped directly into the PA. Most players I know, including myself, have replaced the AO35 with a modern amplifier of at least 100 watts. Not to mention that many old Hammond amps like the AO71 used GZ34/5AR4 rectifier tubes, which you likely know, since some Gibson tube amps use them, that a USA NOS tube will cost you $200, $300 for a vintage NOS Mullard, and $400 for an Amperex Bugle Boy tube! I wouldn't worry about these little amps being used for projects! I have at least 10 of these sitting around waiting to become something useful!!
Although I wouldn't mind owning a SMD-type heat gun. Or better yet, a hot-air SMD rework station, like the DIC Denon SD-2000 or SD-3000. I'm so cheap that I use a 150 Watt spotlight bulb to activate heat-shrink tubing. It works rather well and almost won't damage the tubing, unless left too close, for too long. But, it does take considerable time to do so.
Sick amp, really does sound good. And sick UFO! It has that nice singing tone to leads with some attack. Not at all harsh despite all the gain and highs. And pleasant crunch. This as two channel amp with cleans having some headroom would be perfect.
Some of the characteristics remind me of my Lee Jackson preamp, just with less harsh treble range. I have a feeling it shares some design in the first stages with these kind of small amps that you do, something that does the spanky attack even on drive sounds. I've heard its circuit is following old Fender designs, just with added gain stages.
Rock on! These amp servicing/modding videos have been my binge watch during this lockdown time, can't get enough of them. And trying to suck as much info from them as possible. So far gotten great practical bits about trouble shooting, behavior and fixes to common problems in amps. I feel like someone would be able to build a decent amp just by watching a lot of your channel. Perfect nerding out and ruthless humor. And killer guitar playing of course. Anyway, just wanted to say thanks for this content, the info you share feels reliable contrary to how you often have to second guess a lot of stuff you see on youtube. And it's delightful to see every now and then how you and your kid smile to each other.
John Hammond invented the tube Amp. If your ever in the Salem Mass. area go check out Hammond Castle.
Really COOL place. And they have a couple of his first amps on display.
You won’t believe how big they are.
Great video although quite long. Lol
😎🎸🎶✌️
At about 40:00 that pilot drill bit that you were using looked like one of them rotary butterknives.
The fuse should always be the first thing a power supply hits when it gets to a circuit. The reason is pretty simple. In the event of a fault that blows the fuse, the power is isolated to where it entered the circuit, thus the whole circuit is protected.
NICE TONE
So I've got one that I've just finished my initial mods to which follow many of the suggestions that have been mentioned here. I'm amazed at how quiet the amp is even though the only new parts are in the tone circuit and input. I've also completely removed the NFBL and the zobel network (this was done for me when I powered on the amp and the resistor in the zobel network burned up).
The issue that I've come across is that at about 3-5 on the volume, I get some high pitch squeal. Above that the squeal goes away but the volume is substantially lower and there are a lot of what I assume are odd order harmonics in the distortion (to be honest I'm having a hard time finding a video demonstrating odd order harmonics to be able to confirm my suspicion.
The controls are in the same location as the CG and I ran across another thread a while ago (of course I can't find it now) that mentioned having the controls that close to the OT, can cause some interference and that if that's where you're going to mount it, that you need to have it shielded. Anther possible cause?
I have 2 new, matched output tubes coming as I think I've ruled the pre-amp tubes out through swapping out with some that I had on hand which I knew were good.
Open to any feedback.
P.S. amp sounds great at the volume below where I experience the squealing.
I have a few of these I've done. My favorite conversion is using AO-35 and making a Matchless Spitfire. I usually install them in old dynamite crates. The layouts and schematics are readily available online
I'd be interested in one of them.
I love work like this! Kudos! Totally cool of you to post.
A fine scotchbrite pad is probably a safer thing to use for rust removal in an amp. Only takes one steel wool fibre in the wrong place to cause problems.
Love your show Brad
admittedly i skipped to the end. sounds fantastic!
I FOUND YOU BRO. TIMEHUNTER
@@kevinlong4657 🤣🤣🤣
how you do things works,so its good enough for the people who know you are an excellent amp
builder.that amp sounds absolutely killer and has wicked dynamics and you have some serious
chops my friend.if the amp fixing thing ever stops you could be a gigging monster
The demo was over @ about 1:36:15. Past that it was clear how good the amp sounded by the look on your face/playing lol. You were just having fun after that hahahahaha. Nice work man!
I greatly appreciate the help I'm starting my build this weekend and have been thoroughly studying your video. I absolutely love the outcome you got from this setup. Thanks again I always look foward and enjoy all of your vidoes!
No prob. It's my pleasure. Post a video link when you get it running.
@1:11:36.........Brings back memories of my childhood....when the stomping was rendered useless, the main power fuse(for the basement) was extremely effective...lolol
Another item my father left me a Hammond and it's great and an old Moog.
Hey Brad. I like the videos. Iam an Uncle Doug fan as well. I was wondering; those ceramic disc capacitors you replaced with orange drops.. is it microfarads. in the AO35 ? I only have a basic volt meter and. cant test the capacitors. Thanks.
Wait, at 52:00 I must have have heard wrong.
Yeah, I sorta did hear wrong. A 12AX7 plate is around +210 volts above ground so don't forget and wire the other end of the coax to the input jack end to ground. I've heard of only grounding one end and float the other end so that you don't have ground loops.
I'm trying to figure how that works. The thing that I'm coming up with is the DC doesn't flow but you get a counterpoised (180 degree out of phase) signal on the sheild. Do you know what gives here?
It’s funny mentioning Dr Z in this. What I thought seeing this video was about the fact I’ve been looking for a organ or projector or other similar amp with the right size transformers to build a Route 66 clone. They’re a stupid simple circuit but I love the sound they have.
Nice. Now thats shredding with soul.
Hello, I see you have several Hammond preamps, I was wondering if you have any transformers from the percussion amp section left over. Since you won’t be using it for the guitar amp convention. I’m looking for one for my organ. Thanx
I mounted the board and brackets on additional brackets, so it is horizontal. Much easier to experiment on. The original circuit has plenty of gain once the input components are changed to values suitable for guitar. I don't think it really needs much tweaking beyond that.
Good grief! That is righteous, man! Came here to get information on re-capping a AO-43 (eBay) to double amp great grandmothers M103 (and get practice before re-cap the M103), stay in for all the tips, and settle in for the playing, well done on both build and playing.
41:40 Firstly, a file is to be used forward, dragging back damages the teeth. Secondly, they also make a hole reamer that be faster and easier. Hope this helps.
1:17:10 With more than one ground point, how are you avoiding ground loops? Thanks.
Great video sir! I have an AO 35 amp and this will be my first venture into building my own home brew amp.. I am still learning about how tube amps work, but I've been trying to educate myself through great videos like yours as well as Uncle Dougs. Could you by chance put up a link of your final schematic? I've seen others, but I believe you've done things slightly different than the others, and to be honest, I like the sound of yours the best out of all the ones I've heard. Thanks for helping the way you do!
Removed the Boucherot from an Ao-44 and it did seem to make the tone a bit less “grey” to my ears,at least. I haven’t added a 12ax7 to it so it’s fairly stock other than a bright cap of an unusual value since I experimented with what I had on hand. Always wondered what that part of the circuit was supposed to do. Completely gutted the Ao 35 I have besides the transformers and tubes.. Prolly do the 18 watt thing. Watching this to see where u go with it. :)
Hi Brad...I am attempting my first push pull build. I have a beautiful pair of Tung-Sol 6550's and I read on the internet that a 5Y3 would choke such a build, apparently they thought that little rectifier can't keep up with the power of those 6550 tubes. I have been looking at Rob Robinette's pages and decided to build a 5F6 Bassman with these mighty tubes and would appreciate any advice you might share. The original amp was a Stromberg Carlson P.A. head that used this very same rectifier and as a guitarist, I want to build something useful that sounds good. There are a ton of mods that Rob Robinette uses on his builds and I'm sure I will implement some of them. I have built a "Champ' clone and it turned out great but this build with the phase inverter circuit and a good tone network is lots more than that little Champ circuit was. As always, you clips are much enjoyed and appreciated, as are Uncle Doug's.
The reason converting something like this is preferable to a scratch build is you often get the transformers and chassis and tubes cheaper this way. If you’re stuck on 6550, look into building a 2204 Marshall perhaps. You could use Bassman transformers.
So how do I go about turning back time to when people were giving them away?
1.21 gigawatts and a flux capacitor.
Right....why didn't I think of that!.....lol
Check with churches. That's where I got mine. Once they upgrade to multi channel boards and key boards, they just unplug them and stick them somewhere. You can sometime get awesome tone cabinets/speakers with them as well.
thanks for this- Great job and so helpful- I'm struggling with some the very issues you address and will now try your mods!Only request is for a post of your final schematic.
+Corey Collins at about 1:25:00 in, I talk about the schematic.
roger that- I tried a screen capture but the resolution isn't too great- just thinking a file of that schematic would be so helpful- you did a great job simplifying the AO35 and showing your final layout...
AH! How silly of me not to think of that. Of course it would be a PIA to see a screenshot and print it out. Lemme see if I still have the schematic lying around...
Much obliged!
+Corey Collins Hey Corey...was just thinking about your project and wondering if you ever got it going...
Uncle Doug is my hero. Nice video !
Great video Brad!!! I like vids with lots of detail even on the non sexy stuff/processes.
Sounds great! Would you consider posting your "edited" Hammond schematic online so we can see the changes you made?
Did he ever post the updated schematic?
@@Finom1 Not to my knowledge
Proprietary -knowledge earned through years of hard work
just love this build. Nice work buddy.!.
Thanks, Barry. I'm quite fond of it as well. It's one of those you grin ear to ear after playing.
The Zobel network is there to help eliminate key-click in Hammond Amps. Laurens hated key-click.
Thanks for this comment. I missed it before, but it makes sense that it would soften key attack now that you mention it.
That Bucherot cell looks like a typical Zoebel Bridge, used to adjust for speaker impedance?
EPIC! Great work...I'm a fairly intelligent person but I can't even wrap my head around the world of electronics/schematics and the level of work you do. The amp sounds fantastic. You should put together an online class to teach amp repair. Mojotone occasionally has 2-day workshops at their headquarters where you build your own amp.
I have a Hammond L-100 or thereabouts, that has needed a starter motor for about 30 years. I have a used motor and have tried to give away Hammond and engine for free, to churches, but no one wants it, here in 2020 ... Had an old Leslie too, but termites got into it ... Battin' a thousand, here ...
I really love it when you have a good build and get all fired up...
I'm like happy for you.
Wish I wuz there so I could test a couple of my guitars...
I know I'd be trippin'
keep 'em coming!
cheers
Your welcome
Amazing tutorial and video! The guitar playing at the end was also great. I garbage picked a AO-14 amp out of an M-2 organ in my neighborhood and your results with the tone and sound are inspiring. I see many similarities between the AO-35 amp and mine; however, the AO-14 has several more tubes and is physically larger. Just wondering if anyone has had success with that model amp.
+Mike Choffin You should be able to make that amp into a monster with similar qualities as this AO-35. Of course, you could make it into whatever sort of amp you like. The Hammond transformers are TOPS! Best transformers ever made, probably. Mercury Magnetics have got nothing on these old Hammonds, I assure you. You have probably the best starting platform you could ask for. Some thoughtful and creative designing, and you'll have a great amp, I'm sure of it.
+The Guitologist I may have spoke too soon. The schematic for the T-4 power transformer shows three output voltages from the secondary windings. 5- , 6.3- and 340-volts. I don't get power from any of the secondary taps. I'd guess that the main power transformer is dead. The footprint of the model you converted is much smaller than the AO-14, nearly 22" long. I may just wait to see if I can find one like you converted.
+Mike Choffin
Hi Mike,
How many watts is the AO-14?
Is it more than the AO-35?
Thank you.
+Finom1 'm not sure. I new to this and learning as I go. Like I stated above, I garbage -picked the amp section and speaker an M-2 organ that someone in my neighborhood was throwing-out. From what I can tell reading on the internet, both amps will produce very powerful sound output.
Looks like a great project.
@@Finom1 AO-14 uses 6V6 power tubes worth 14 watts each at best.
Awesome! Rock Bottom! 🛸
Amazing video! On one of my computers I use a Mullard Altobass / Stereo 44 amp (EF86 - EL84) amp from 1967. Apart from the valves (its on it's third set) everything is original and it does make some popping sounds within the first minute of starting up but works fine, sounds stunning with anything from classical to dubstep. I've got a Trix push-pull EL84 amp in the garage I've been meaning to rebuild for decades - might get on with it now! :o)
You HAVE to silkscreen this with an "11" on the volume..
What a wonderful sound, cant beat valve (tube) amps
This is GREAT! Thank you. I just re-capped mine and hope to wire up the pots soon. One question though, I have a reverb unit I salvaged from a marshal amp. How would I wire in a "effects loop" with a Pot to control it?
That's really outside the scope of this video, but you might might useful information on this forum: el34world.com/Forum/index.php?topic=10208.0
Thanks for watching and good luck!
Yeah, i know I just figured you'd be the guy to ask about it. Maybe not an effects loop though. Most amps just have a Pot for reverb. I figured that would be easy enough to insert near the tone stack? I'm really a noob when it comes to understanding this stuff but I seem to be able to follow directions well! This will make my second tube project. The first was recapping a Bogen DB230 stereo. (sounds great!)
Oh, and is there any reason I shouldn't mount this amp upside down in the top of a custom built cabinet (tubes in the rear plugging up into the box) That's kinda been my vision for this project but I've only seen guys mount them in the bottom of the cabs.
Several quick questions please. 1. What did you do with the green wire you clipped from the terminal strip at the beginning of the video? 2. Where is the tone stack wired in at? 3. Where is the lamp wired in at? My project is almost complete and I need you assistance.
Beat sounding amp I've heard in awhile....
I need help buildin a silvertone medallion hifi stereo from the 50's clone I just need a good coach like you Brad it all starts with a schematic.
My B3 burnt in a house fire. I can't tell you how much I miss it!!!! :(
Interesting video. Would you please post a link to the schematic you ended up with in the description?
'Enough guitar amps in the world?' Say it ain't so!
1:37:50 Guitologist unleashed hahah!
Is it possible to convert this amp for guitar and keep the reverb? Maybe adding an additional tube to drive the tank? I’d love to get some feedback on the best way to do that.
how hard would it be to use an EF86 as the first preamp tube? I have an old AO 35 that's been lying around the shop for years. thanks for posting this. Uncle Doug demoed one but didn't get into the details of the conversion like you did. great job.
+zendixie Thanks for watching and commenting! An EF86, being a single pentode, you may actually end up losing some gain and volume overall because you're trading the first two stages of triodes for one pentode. I'm sure we could look at the datasheets and do the calculations and figure out exactly how much you'd lose, but I'm guessing it would be significant, and the end result would be very different than what I ended up with here. If you're looking for a far cheaper alternative to the EF86 to have a pentode up front, you can also check out the 6GH8A. Similar to a 7199. It has a triode AND a pentode in the same envelope. You can retain the two gain stage architecture without adding another tube socket.
+The Guitologist I'm trying to find a way to get a cheaper Winfield Cyclone. Also the Super 17 amps started as AO35 amps and I think some of those used an ef86 , maybe followed by another 12ax7. Matchless DC 30s use the ef86 as well. the gain may be less but to me the tone makes up for it.
That's an INCREDIBLE sounding amp Bra!!! I'd love to have one to run through a 412 Cab!!!