16uF-16uF @ 450 WVDC for filtering the B+ rail and 8uF @ 200 WVDC for the preamp part of the rail. Too much filtering and it's not an AC30 anymore at all. We call lamp cord "zip cord" in the USA. You can pull it apart and unzip it into two wires.
Ok. Brilliant. Looks like you know your stuff! Just found your channel. Lyle / Psionic audio mentioned you in 1 of his recent videos. I think a Marshall DSL 40c. I ain't no amp tech or anything. I own heaps of guitars amps n pedals but don't play real good either. Just really interests me. By the way, I live near Newcastle NSW. I'll be watching a heap of your other videos too. Cheers
Nice to see you working on an amp that deserves your skill and attention to detail. I'm thinking this one will be a lot more fun than some of your recent Saturday morning adventures :-)
WRT Hamond tube, if it's made in Holland it will be almost certainly a Philips tube and very slight possibility of Amperex. WRT screen Resistors, 1k will give some extension on life but they will also sound slightly different... depends how picky the owner is or if he / she can even hear difference. Most old AC30's I've worked on have been running well over 100% max plate dissipation. The problem is they usually sound really good running that way :( . There is a solution but you will have to pm me for it.
Is this from the "She ain't set-up" series? Love your work Brad and thanks for sharing it. The apple didn't fall far. Great specimen of the JMI series Vox. Psionic is smiling. Hammond recruited many early tubes for their organs, leslies, as well as others did back in the early days. the circuit has been modified/serviced before too. Go with the el84 reliability mods. Yes the el84 circuits are purposefully abused, in fenders and others as well. They used to be cheap. No more. A cooler bias will deal with voltage/amperage shifts better than a hot bias with no negative effects. Wall voltages often shift 20volts or so. There lies the Rub.
The Jennings AC30 I have in right now has rather large single section TCC filter caps. They are large enough I can stuff the two modern 16uFs and the 8uF into one can.
My god people, please stop modding original amps! Even that old Silverface Bassman you’re thinking about taking to a hack-tician deserves better. Dielectric grease serves exactly one purpose to me. A torque damper in a pot, like they come from the factory.
Not sure I agree with the point about stranded wire. It's very prone to breaking if soldered and then subject to repeated stress at the point where the solder ends.
Given that the el84 do not have separate cathode resistors all 4 must be matched for current . Given that and 100 ohm screen resistors will burn them up fast and not evenly . Designed when match quad was easy to get. IMHO given current production each el84 should have 200 ohm to each cathode having a by pass cap . This said it is more bench time and cost . Changing the original design to match current parts .
Good work Brad! By the way, I'm liking your face-to-camera work of late. Is it a new camera? Everything is looking way better, especially your close-up shots. Looking forward to part 2. Where will you put your filament ground reference? EL84s Cathode? That should get you around 12v.
You are thinking of a "spring nut J clip" not a Fahnestock clip. They kind of have a single screw thread stamped into them before they get bent into a J or a U to clip onto the sheet metal and in rapid assembly some workers will just ram the screws in then give a final twist to tighten them up or strip them out.
@@BradsGuitarGarage Specifically west coast Canadian - mostly from British Columbia it seems. Where I am in Ontario, I've only ever heard it on AVEs videos....
After watching the walk-through, this AC30 is a lot like how the Cambridge Reverb I worked on was built... all solid core wire, wrapped around the eyelets like 3-4 time, 3-4 wires crammed in each eyelet. No grid stoppers, no heater balancing, components stacked on top of each other in a chassis about 1/5th the size of that AC30. No wonder it took me 6 months to get it working again! Hehe! Good luck Brad! I know you will make this thing solid.
There really is no way to accurately predict all the hours that need to be poured into these units to get them purring, mate. But I think they're totally worth it. And that's why I'll never be rich. LOL!
At 3:30, the term your searching for is *Tinnerman nut*, also known as a "speed nut", a fastener that clips onto the edge of sheet metal and allows you to thread a self tapping sheet metal screw into the speed nut. A Fahnstock (Pfanstock?) clip is a type of electrical connector for attaching bare wires that was often used on 1920 battery-powered radios and homebrew radios of the 20's and 30's.
Hammond branded preamp tubes are most often Telefunkens or Amperex, look for the T. diamond on the bottom, if absent it's a Bugle Boy. Hammond EL84s are almost always Telefunkens (keep it a secret! 🫢)
I forgot to talk about heater elevation when I talked about groud referencing. Sorry, I'll cover that in ep. 2.
16uF-16uF @ 450 WVDC for filtering the B+ rail and 8uF @ 200 WVDC for the preamp part of the rail. Too much filtering and it's not an AC30 anymore at all. We call lamp cord "zip cord" in the USA. You can pull it apart and unzip it into two wires.
That’s a very clean cab for a JMI.
Ok. Brilliant. Looks like you know your stuff! Just found your channel. Lyle / Psionic audio mentioned you in 1 of his recent videos. I think a Marshall DSL 40c. I ain't no amp tech or anything. I own heaps of guitars amps n pedals but don't play real good either. Just really interests me. By the way, I live near Newcastle NSW. I'll be watching a heap of your other videos too. Cheers
Looking forward to the upcoming series of repairs on this vox and the marshall. The new editing and camera work is really nice as well.
Nice to see you working on an amp that deserves your skill and attention to detail. I'm thinking this one will be a lot more fun than some of your recent Saturday morning adventures :-)
WRT Hamond tube, if it's made in Holland it will be almost certainly a Philips tube and very slight possibility of Amperex.
WRT screen Resistors, 1k will give some extension on life but they will also sound slightly different... depends how picky the owner is or if he / she can even hear difference. Most old AC30's
I've worked on have been running well over 100% max plate dissipation. The problem is they usually sound really good running that way :( . There is a solution but you will have to pm me for it.
Is this from the "She ain't set-up" series? Love your work Brad and thanks for sharing it. The apple didn't fall far. Great specimen of the JMI series Vox. Psionic is smiling. Hammond recruited many early tubes for their organs, leslies, as well as others did back in the early days. the circuit has been modified/serviced before too. Go with the el84 reliability mods. Yes the el84 circuits are purposefully abused, in fenders and others as well. They used to be cheap. No more. A cooler bias will deal with voltage/amperage shifts better than a hot bias with no negative effects. Wall voltages often shift 20volts or so. There lies the Rub.
That amp is lucky it found you. Far from a train wreck, but definitely a basket case. Good one my friend.
You Sir are a CHAMPION! A second classic amp done the Brad way, BRAVO!!
Teflon insulated wire rocks. My only complaint is the insulation is hard and makes me fingers hurt after a day at the bench. Yeah, I'm a wimp.
The Jennings AC30 I have in right now has rather large single section TCC filter caps. They are large enough I can stuff the two modern 16uFs and the 8uF into one can.
Great stuff! wish I owned it. can't wait to see what you do with it! I bet this would sound nice paired with the superbass!
My god people, please stop modding original amps! Even that old Silverface Bassman you’re thinking about taking to a hack-tician deserves better.
Dielectric grease serves exactly one purpose to me. A torque damper in a pot, like they come from the factory.
Not sure I agree with the point about stranded wire. It's very prone to breaking if soldered and then subject to repeated stress at the point where the solder ends.
This bloke almost looks like he knows what he's doin! haha nice one mate.. great vid and the beards even better \o/
Goodness gracious the beard
Given that the el84 do not have separate cathode resistors all 4 must be matched for current . Given that and 100 ohm screen resistors will burn them up fast and not evenly . Designed when match quad was easy to get. IMHO given current production each el84 should have 200 ohm to each cathode having a by pass cap . This said it is more bench time and cost . Changing the original design to match current parts .
A lot of crude "wiring" going on in there.
Ahh, but did you bring it up to Lyle's standards!? Haha just kidding, great video, mate!
We did confer, but I could never Lyle better than Lyle.
Good work Brad! By the way, I'm liking your face-to-camera work of late. Is it a new camera? Everything is looking way better, especially your close-up shots. Looking forward to part 2. Where will you put your filament ground reference? EL84s Cathode? That should get you around 12v.
Just some new lighting panels, mate. Got some Lumipad 25's above the bench now and a few smaller ones for fills etc.
@@BradsGuitarGarage they made an noticable improvement, Brad!
You are thinking of a "spring nut J clip" not a Fahnestock clip. They kind of have a single screw thread stamped into them before they get bent into a J or a U to clip onto the sheet metal and in rapid assembly some workers will just ram the screws in then give a final twist to tighten them up or strip them out.
That's the one! Thanks mate.
😄😎
Nice! Beard matches the grill, you're definitely the man for the job! ;)
Beautiful shots. Thanks for your har work putting this together. Really enjoyable.
Another interesting one 😉 !
Vox layouts seem very intricate to me compared with Fender or Marshall.
Not the usual horror show of a cab you seem to usually get. I'm sure you'll have it sounding as it should soon enough.
Is choocha Aussie slang for doo-hickey?
It's actually Canadian. As in: "skookum choocher".
@@BradsGuitarGarage Specifically west coast Canadian - mostly from British Columbia it seems. Where I am in Ontario, I've only ever heard it on AVEs videos....
Excited to follow along! I've got my own 64 ac10 project coming up soon so I'm excited to pick up some tips and tricks along the way from you
Glad to have you here, mate!
And congratulations on your wicked channel!
Another great amp, can't wait to see how this one turns out along with the Superbass
After watching the walk-through, this AC30 is a lot like how the Cambridge Reverb I worked on was built... all solid core wire, wrapped around the eyelets like 3-4 time, 3-4 wires crammed in each eyelet. No grid stoppers, no heater balancing, components stacked on top of each other in a chassis about 1/5th the size of that AC30. No wonder it took me 6 months to get it working again! Hehe!
Good luck Brad! I know you will make this thing solid.
There really is no way to accurately predict all the hours that need to be poured into these units to get them purring, mate.
But I think they're totally worth it. And that's why I'll never be rich. LOL!
At 3:30, the term your searching for is *Tinnerman nut*, also known as a "speed nut", a fastener that clips onto the edge of sheet metal and allows you to thread a self tapping sheet metal screw into the speed nut. A Fahnstock (Pfanstock?) clip is a type of electrical connector for attaching bare wires that was often used on 1920 battery-powered radios and homebrew radios of the 20's and 30's.
"speednut".
In the UK, they're called "Motorhead"!
I would love to see a series "Brad's questions answered by amp. designers" it could end up a very long running programme. 👍👍
I think I'd know the answer to most of those questions already, mate!
Does the grill cloth on a
Vox shrink a little bit, to tighten and snug it up, when hit with a hair dryer?
A little bit. But it tends to loosed off again when it cools down, unlike Fender type grille cloth where it stays taught afterward.
@@BradsGuitarGarage , "taught"?!🤔😉 "Well I guess that 'taught' ya not to mess with me and my heat gun, you saggy griille cloth!" says Brad! 🤣
Hammond branded preamp tubes are most often Telefunkens or Amperex, look for the T. diamond on the bottom, if absent it's a Bugle Boy. Hammond EL84s are almost always Telefunkens (keep it a secret! 🫢)