Really really interesting info, thanks for taking the time! Just earlier today I noticed a "papery" sound kind of on top of the distortion on an old JTM45 build of mine. Gonna have to look for DC on the input grids now!
I built one of these with a PPIMV. I really like the combination of 2x10s, 6L6s at moderate power and that classic preamp & cathode follower circuit. With a treble booster in front it gets that classic Bassman / Marshall growl, but it's also got enough headroom and firmness in the power supply for really good cleans. One of my favourite amps ever.
Similar "tropical fish" caps were used in older European hifi equipment (such as Bang &Olufsen, ugh) and sometimes in solid-state McIntosh equipment. They do fail, probably from moisture infiltration; the epoxy-like coating is prone to cracking.
so faithful to the original,it even embodies all the original defects of old 50s productions,i guess if sometimes there's also a wiring/component value mistake,just for reality check
5F4, my favorite tweed! I disagree on the 12AX7. Totally different amp with a 12AY7 in V1. I also used a 12AT7 in V3/the PI to further reduce gain and sweeten up the amp. A 220K resistor to the CF's grid helps as well. I put 470K mixing resistors in my friends 5E7 who insisted on using a 12AX7 in V1 to even things out.
I’m kinda shocked that its already got a bit of tweed disease. That’s probably why the previous guys didn’t catch that. I took the way I wire the line/primary from Clark. Using the polarity switch as a terminal strip and all. I think they make the best Tweed clones commercially available. As an end user and (very)part time builder, I look at Jupiter like I look at Mercury Magnetics. US made quality serving a very niche community. I’ve been a very satisfied customer of theirs for years now. BTW, I take apart the 1M linear CTS pots for their wafers. It’s worth the effort if you want a CTS pot. They’re the only thing I’ll use in an amp. Specifically the ones with a brass shaft and collar. The newest Mojotone “vintage taper” 250k and 500k are marked J, previously marked as BD. I just noticed that on Sunday when I was rifling through my big bag of pot(s).
So is it moisture in the board itself causing leakage? Displaced by isopropyl alcohol. What is the board made of some kind of laminated paper? I wonder if the amp was kept in a high humidity environment.
I own a Clark Edisto which is also a Super circuit (but with 3 knob reverb added) and for twenty years I had similar issues including the static with the guitar volume on the bright channel only. The static would improve with input jack cleaning but always returned along with noisy microphonic capacitors on the far right of the board as shown above . Also, the amp was always very poor sounding to my ears at lower volumes, no real useable low volume settings and harsh - above "6" it came alive - thanks to videos like this one i recently replaced both volume pots with 1meg linear tapers and both bright side input jacks and I now have a great sounding tweed era super - the issue with guitar volume static and noisy caps/leaking DC gone (i think the original Switchcraft jacks were bad from day one) - all said the quality and performance of Clark amplifiers is stellar - I have a few others and all over twenty years old and sound as good if not better then the day they were delivered. Thanks again for your posts - very helpful to me resolving my amp issues!!
Oh man, I have the same problem on my bright input on a 5e3 Beaufort. Beautiful sounding amp, the crackle and static is absolutely annoying and I couldn't figure out why. Gonna see if this is it.
@@MintStiles i am not a trained amp tech but i think those bright channel input jacks leaked DC back to the circuit causing the noise - also when i tapped the caps and board on that side of the board they where microphonic as well - replacing the inputs cleared all that up and improved the tone a bit as well - the linear tracking volume pots also a big change - I have a Beaufort as well but no problems with that one - good luck
should be linear "tapper" pots - they are 1mg - also the inputs have a 1meg carbon comp resistor as well - also you may just need to clean and retension the inputs with a product like Deoxit D5 - it worked temporarily for me but the problem kept returning
Revisiting a question I asked earlier, do you think that Leo implemented the standby switch because it was useful in his errant design, or did he implement it because, as some folks have suggested, he misunderstood the RCA Tube Manual? Sorry if I'm misunderstanding, but I did re-listen to your comments about this at least five times! Thanks for any insight you can give me into this, I'm just trying to understand why standby switches appear on guitar amps but not on any other tube audio amps that I know of. You previously directed me to your video "Does this amp need standby," which answered a lot of questions, but I still wonder why Leo Fender initially decided on its use, which as far as I can tell was novel and unique to Fender instrument amplifiers.
AFAIK he implemented it to avoid using more expensive caps rated for the unloaded B+ in some of his designs, it was perceived as a "high end option" and then put on amps that didn't need it, just for the "high end" association.
@@PsionicAudio It was for practical reasons that he included a standby switch. In those days there were a lot of club gigs. Leo got a lot of input about his products from club musicians. When musicians went on break they would just flip the standby switch so the amp could cool off for a little while. The heaters are still on of course in standby. Break is over, flip the standby switch and you're ready to go without having to wait for the amp to warm up from a full off state. It's really that simple.
There is a statement at 6:50 that you may wish to elaborate on… there needs to be voltage on the grid, the cathode resistor and grid leak resistor to ground create the bias voltage to control the tube
The real elaboration is quite literally chapter length, but fortunately that chapter already exists: www.valvewizard.co.uk/gainstage.html But to give a shorter answer, the gain stage here is an AC-coupled cathode biased triode stage, and while you need AC voltage on the grid for amplification to occur, you do NOT want DC voltage on the grid (as was leaking here through the board). I'm about to put together the follow up video, and I'll include a brief discussion of this to avoid any confusion.
@@PsionicAudio I am letting you know that I have all the books and read them constantly and also build amps myself. I am a lot like you in many ways actually
Then you'll know how hard it is to present this stuff for a general audience. How much to simplify, when to elaborate, and also (in this case) when something obvious to me isn't necessarily obvious to the viewer. I really respect Uncle Doug's planning and presentations (even though I disagree with him on some particulars).
You are doing a great job sir, much respect. I wish I could have privately suggested discussing neg voltages showing on the grid for bias. My uncle was a tv repair man named Lyle. He trained in 60’s. Fixed tv and stereos all his life. Once he told me, when I was 20,”Tubes are dinosaur technology, why you want to know about them. They make transistor guitar amps now!” That was 30 years ago. I didn’t listen.
When I was a young recording engineer in Los Angeles in the early 70s, I was 'taught' that potentiometers are at their best at 3/4 open; because, below that the circuit flow is 'pinched' and above that harmonic distortion is being added to the stream. These days I see a lot of guitarists say that "2 o'clock sounds best." Well, 2 o'clock is a potentiometer at 3/4 open. Is this a thing for you, and if not, I'd love to hear your take on this (and restricting signal flow). Also, I'm glad to hear you talking about "that torn paper sound" which I believe does not belong attached to the sound of a guitar because it is extraneous to the core tone. An unwelcome passenger.
Well, sorry to argue, but there is no merit to the "3/4" concept. An audio taper pot is really at around 50% of its value when the knob is 3/4 of the way up. What is really happening there is you, like most humans, like the sound of louder things. But as far as what is happening in the circuit, nothing is "pinched" below that point. Duane didn't have his volume pots very high on Elizabeth Reed. SRV didn't have the volume high on Lenny. They both sound a little bit ok.
@@PsionicAudio No argument. That's why I asked for your input on the matter. It was the 1970s after all. And I think that they were talking about faders as well (which is why the zero is where it is on faders). I must have assumed that the same was true for all potentiometers. You have shown me there are more than one type. It's why I asked. I trust you a lot, so I'll probably ask lots of stupid questions while I am still alive and learning. Thanks Lyle!
That board looks really flimsy and cheap compared to the rest of the amp's parts. Would a fiberglass board have stopped dc leakage in the first place? Seems weird they spent so much on components yet used what looks like cardboard for the eyelet board.
Jupiter caps and a fiber eyelet board? To each his own. That board would would be GLASS resin as in fiberglass, not fine sawdust and resin, especially with some of this NEW fiber board that is imported. That stuff has leaky spots new from the factory. That is an awful lot of work to put on a leaky board or on a board that will become leaky prematurely. Fortunately, I have hi pot insulation breakdown testers and e stat testers, but I am still running the risk that stuff will leak later on.
These are now crazy overpriced. Tons of other tweed builders using decent parts for way less than Clark. He was one of the first doing the Tweed clones way back when. Now a ton of competition. Shop around.👍🏻
Видеоклипы
Golly I love this channel. Thanks, Mr. Psi.
I have a Clark Tyger, the 57 bandmaster with the reverb added and I love it. Mine came with 12AY7 in V1.
Thanks for another great video.
Really really interesting info, thanks for taking the time! Just earlier today I noticed a "papery" sound kind of on top of the distortion on an old JTM45 build of mine. Gonna have to look for DC on the input grids now!
Great video as always 👊😎
Looks well made Lyle, but seems like you found a few sneaky issues.. Great video, and fab info..Ed..UK..😁
Never heard of these guys before. Good info, cheers mate! xD
Thanks Lyle. Again - here’s a third brand I was unaware of!
I built one of these with a PPIMV. I really like the combination of 2x10s, 6L6s at moderate power and that classic preamp & cathode follower circuit. With a treble booster in front it gets that classic Bassman / Marshall growl, but it's also got enough headroom and firmness in the power supply for really good cleans. One of my favourite amps ever.
The PI input on these can be padded down to sweeten the od too. Nice work man.
In the 50's there was no guarantee which side of the switch was hot.
Like amp geekery keep it coming
Similar "tropical fish" caps were used in older European hifi equipment (such as Bang &Olufsen, ugh) and sometimes in solid-state McIntosh equipment. They do fail, probably from moisture infiltration; the epoxy-like coating is prone to cracking.
so faithful to the original,it even embodies all the original defects of old 50s productions,i guess if sometimes there's also a wiring/component value mistake,just for reality check
5F4, my favorite tweed! I disagree on the 12AX7. Totally different amp with a 12AY7 in V1. I also used a 12AT7 in V3/the PI to further reduce gain and sweeten up the amp. A 220K resistor to the CF's grid helps as well. I put 470K mixing resistors in my friends 5E7 who insisted on using a 12AX7 in V1 to even things out.
Love mine, 12AY7 in V1.
I’m kinda shocked that its already got a bit of tweed disease. That’s probably why the previous guys didn’t catch that. I took the way I wire the line/primary from Clark. Using the polarity switch as a terminal strip and all. I think they make the best Tweed clones commercially available.
As an end user and (very)part time builder, I look at Jupiter like I look at Mercury Magnetics. US made quality serving a very niche community. I’ve been a very satisfied customer of theirs for years now.
BTW, I take apart the 1M linear CTS pots for their wafers. It’s worth the effort if you want a CTS pot. They’re the only thing I’ll use in an amp. Specifically the ones with a brass shaft and collar. The newest Mojotone “vintage taper” 250k and 500k are marked J, previously marked as BD. I just noticed that on Sunday when I was rifling through my big bag of pot(s).
I can see a Fender in there. Reminiscent of Lupe’s work from back in the day. Makes you wonder how many amps she wired up for Fender. Enjoy your day.
BTW, I sold a fair bit of NOS parts to Michael Clark, some 20+ years ago, mostly tube sockets and vintage chicken-head knobs and such.
So is it moisture in the board itself causing leakage? Displaced by isopropyl alcohol. What is the board made of some kind of laminated paper? I wonder if the amp was kept in a high humidity environment.
Pity about the problem, that is a really nice neat looking build.
Stay tuned! Not long now...
I own a Clark Edisto which is also a Super circuit (but with 3 knob reverb added) and for twenty years I had similar issues including the static with the guitar volume on the bright channel only. The static would improve with input jack cleaning but always returned along with noisy microphonic capacitors on the far right of the board as shown above . Also, the amp was always very poor sounding to my ears at lower volumes, no real useable low volume settings and harsh - above "6" it came alive - thanks to videos like this one i recently replaced both volume pots with 1meg linear tapers and both bright side input jacks and I now have a great sounding tweed era super - the issue with guitar volume static and noisy caps/leaking DC gone (i think the original Switchcraft jacks were bad from day one) - all said the quality and performance of Clark amplifiers is stellar - I have a few others and all over twenty years old and sound as good if not better then the day they were delivered. Thanks again for your posts - very helpful to me resolving my amp issues!!
Oh man, I have the same problem on my bright input on a 5e3 Beaufort. Beautiful sounding amp, the crackle and static is absolutely annoying and I couldn't figure out why. Gonna see if this is it.
@@MintStiles i am not a trained amp tech but i think those bright channel input jacks leaked DC back to the circuit causing the noise - also when i tapped the caps and board on that side of the board they where microphonic as well - replacing the inputs cleared all that up and improved the tone a bit as well - the linear tracking volume pots also a big change - I have a Beaufort as well but no problems with that one - good luck
should be linear "tapper" pots - they are 1mg - also the inputs have a 1meg carbon comp resistor as well - also you may just need to clean and retension the inputs with a product like Deoxit D5 - it worked temporarily for me but the problem kept returning
Went to the site... boutique-ville
Crayola caps?
Revisiting a question I asked earlier, do you think that Leo implemented the standby switch because it was useful in his errant design, or did he implement it because, as some folks have suggested, he misunderstood the RCA Tube Manual? Sorry if I'm misunderstanding, but I did re-listen to your comments about this at least five times! Thanks for any insight you can give me into this, I'm just trying to understand why standby switches appear on guitar amps but not on any other tube audio amps that I know of. You previously directed me to your video "Does this amp need standby," which answered a lot of questions, but I still wonder why Leo Fender initially decided on its use, which as far as I can tell was novel and unique to Fender instrument amplifiers.
AFAIK he implemented it to avoid using more expensive caps rated for the unloaded B+ in some of his designs, it was perceived as a "high end option" and then put on amps that didn't need it, just for the "high end" association.
@@PsionicAudio It was for practical reasons that he included a standby switch. In those days there were a lot of club gigs. Leo got a lot of input about his products from club musicians. When musicians went on break they would just flip the standby switch so the amp could cool off for a little while. The heaters are still on of course in standby. Break is over, flip the standby switch and you're ready to go without having to wait for the amp to warm up from a full off state. It's really that simple.
😎👍
There is a statement at 6:50 that you may wish to elaborate on… there needs to be voltage on the grid, the cathode resistor and grid leak resistor to ground create the bias voltage to control the tube
The real elaboration is quite literally chapter length, but fortunately that chapter already exists:
www.valvewizard.co.uk/gainstage.html
But to give a shorter answer, the gain stage here is an AC-coupled cathode biased triode stage, and while you need AC voltage on the grid for amplification to occur, you do NOT want DC voltage on the grid (as was leaking here through the board).
I'm about to put together the follow up video, and I'll include a brief discussion of this to avoid any confusion.
@@PsionicAudio I am letting you know that I have all the books and read them constantly and also build amps myself. I am a lot like you in many ways actually
Then you'll know how hard it is to present this stuff for a general audience. How much to simplify, when to elaborate, and also (in this case) when something obvious to me isn't necessarily obvious to the viewer.
I really respect Uncle Doug's planning and presentations (even though I disagree with him on some particulars).
You are doing a great job sir, much respect. I wish I could have privately suggested discussing neg voltages showing on the grid for bias. My uncle was a tv repair man named Lyle. He trained in 60’s. Fixed tv and stereos all his life. Once he told me, when I was 20,”Tubes are dinosaur technology, why you want to know about them. They make transistor guitar amps now!” That was 30 years ago. I didn’t listen.
When I was a young recording engineer in Los Angeles in the early 70s, I was 'taught' that potentiometers are at their best at 3/4 open; because, below that the circuit flow is 'pinched' and above that harmonic distortion is being added to the stream. These days I see a lot of guitarists say that "2 o'clock sounds best." Well, 2 o'clock is a potentiometer at 3/4 open. Is this a thing for you, and if not, I'd love to hear your take on this (and restricting signal flow). Also, I'm glad to hear you talking about "that torn paper sound" which I believe does not belong attached to the sound of a guitar because it is extraneous to the core tone. An unwelcome passenger.
Well, sorry to argue, but there is no merit to the "3/4" concept. An audio taper pot is really at around 50% of its value when the knob is 3/4 of the way up.
What is really happening there is you, like most humans, like the sound of louder things. But as far as what is happening in the circuit, nothing is "pinched" below that point.
Duane didn't have his volume pots very high on Elizabeth Reed. SRV didn't have the volume high on Lenny.
They both sound a little bit ok.
@@PsionicAudio No argument. That's why I asked for your input on the matter. It was the 1970s after all. And I think that they were talking about faders as well (which is why the zero is where it is on faders). I must have assumed that the same was true for all potentiometers. You have shown me there are more than one type. It's why I asked. I trust you a lot, so I'll probably ask lots of stupid questions while I am still alive and learning. Thanks Lyle!
You should consider taking an apprentice Lyle?
That board looks really flimsy and cheap compared to the rest of the amp's parts. Would a fiberglass board have stopped dc leakage in the first place? Seems weird they spent so much on components yet used what looks like cardboard for the eyelet board.
So was that a kit?
Great vid ...thanx
Didn't mean to be sarcastic
Jupiter caps and a fiber eyelet board? To each his own. That board would would be GLASS resin as in fiberglass, not fine sawdust and resin, especially with some of this NEW fiber board that is imported. That stuff has leaky spots new from the factory. That is an awful lot of work to put on a leaky board or on a board that will become leaky prematurely. Fortunately, I have hi pot insulation breakdown testers and e stat testers, but I am still running the risk that stuff will leak later on.
Aside from that, it's an exceptionally fine looking job of assembly, soldering and basic design execution.
"Tweed Disease" on a young amp....... how interesting. Keep your amp rooms dry my friends.
These are now crazy overpriced. Tons of other tweed builders using decent parts for way less than Clark. He was one of the first doing the Tweed clones way back when. Now a ton of competition. Shop around.👍🏻