Wednesday, 25 October 2017

JHS Twin Twelve V1

From the source:

The JHS Twin Twelve is the first effects pedal to go after the sound of the short-lived but revered Silvertone 1484 Twin Twelve. Available through the Sears catalog from 1963 - 1967, the Twin Twelve was not regarded in its day as a premier amplifier. However, modern players looking for a vintage sound have increasingly turned towards this Silvertone as a primary stage and recording amp. Artists such as Beck, Death Cab For Cutie, Vampire Weekend, The White Stripes and even Coldplay have used the Twin Twelve amp on stage, making it the vintage amp with the most indie-cred. With the market for original specimens drying up and prices increasing, JHS has come to the rescue by putting that sound in an easy-to-use pedal.

 The original was a 60 watt, all-tube head with a separate 2x12 cabinet. At the heart of its sound was a Baxandall tone circuit, powered by a pre-amp the broke up in a way that few other amps do. It wasn't as glassy or snappy as a Fender Tweed, or as treble-rich as a Vox from that period. Rather than going into harmonic crunch like a dimed Marshall, the Silvertone 1484 would get borderline fuzzy, with a very saturated and thick natural overdrive. Its satisfying clean-ish grit and woolly overdrive have become a defining sound in modern indie rock.

Part of the magic is in the charge pump, which ramps up the standard 9V power it takes to 18V, giving the Twin Twelve pedal even more headroom and punch. The Twin Twelve then uses a series of discrete transistors that mimic the valve stages of the original Silvertone. Bass and treble controls remain true to the ratios of the original amp, while separate Gain and master Volume knobs help you achieve the thick, high-gain saturation at low volumes that was only possible by diming the amp back in the '60s.  





42 comments:

  1. Oh boy.. I've been waiting for this one for a LONG time. Thanks for posting it!

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  2. Which IC are you using with this one? Missing from layout. Thanks!

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  3. I think there is a problem here on this perf layout. if you look at the incoming 9+ bat voltage it goes nowhere and shorts the IC.

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    1. the ic is a MAX1044 and isn't shorting out, it's a voltage doubler.

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  4. making this for sure, when biasing the trimmers to 50% are we talking 4.5v or 9 v at it runs at 18v

    or are we talking see what the max and min the trimmer goes to and use half of the number?

    I've had nothing but trouble with J201's in the past, they're a pain in the arse

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    1. Bias to 9V since the charge pump puts out 18V.

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    2. I can get the first 3 trimmers to 9v, but the last one will only go
      to a min of 10.5v

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  5. I think you might need to look at the cuts around the second transistor from the bottom - you have the voltage going to the supply rather than drain. Can that be right?

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    1. You're right, the voltages sound be going to the drain not supply. I was moving stuff around and missed that. I'll fix it later today.

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  6. layouts's been updated with the IC and fixed the transistor.

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  7. This comment has been removed by the author.

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  8. Replies
    1. Pretty sure you can. Also, lt1054.

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    2. Great, going to try it this weekend.

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    3. @hans - did you build this with a ICL7660? I am using one and i think pin1 is NC?

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  9. Is there any proof that this is the real JHS Twin Twelve schematic?

    I first saw this circuit pop up on effectslayouts.blogspot.com. It's the first result if you Google "JHS Twin Twelve schematic." They state that their source schematic is this image: http://guitar-fx-layouts.42897.x6.nabble.com/file/n18170/destijl%2520revision%25202.jpg

    ...which, interestingly enough, comes from this very website's forum. Just do a search for "Silvertone"; it's the thread titled "Silvertone 1485/Twin Twelve." That thread traces back to a post on freestompboxes.org titled "eighty seven percent - De Stijl."

    This circuit is an individual's attempt at doing a tube -> FET conversion of a Silvertone amplifier circuit. I have seen no evidence that this is the actual schematic for the JHS Twin Twelve.

    However, I'm glad to be proven wrong, if someone can provide a source.

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  10. Hi,
    Nice Layout. If you swap 12k and 47R on the rifgt side, you have open lugs for the volume pot.

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  11. Oh, and +9V should go to the upper right corner, not the left I think.

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  12. and Q3 seems to be upside down, drain should face toward supply

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    1. Yeah Q3 still isn't right. I didn't want to be Mr Poopypants because I already mentioned it was a bit dodgy and I'm sure Zach knows more than I do! But I don't think it will work as-is.

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    2. Yeah Q3 still isn't right. I didn't want to be Mr Poopypants because I already mentioned it was a bit dodgy and I'm sure Zach knows more than I do! But I don't think it will work as-is.

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    3. No worries. Yea it's still wrong. I quickly tried to fix it during the height of my finals, so I wasn't all there if you know what I mean. It's real quick easy fix and I'll fix it when I get home.

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  13. Finally got home and fixed the layout. super quick easy fix. Q3 should now have power going to the drain as it should.

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  14. fixed the location of the +9V, had to flip it to the other side of the IC.

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  15. Couple of stupid questions here, please forgive me. Volumes 1,3 and gain 2 are on the rim of the board. Is there a reason for that? I have never seen that before. Is it a mistake? Again please forgive me if that is a stupid question.

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    1. my fuck up when i was moving stuff around. fixed the layout, cause it should have been 20x20 making those connections to the board.

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    2. Awesome tyvm. NOW thinking about it I feel pretty stupid lol I should have known that was the case. anyway thank you for fixing it. I plan on making it in the next week or 2. I have a very busy schedule and a huge honey-do list from the wife, but it is next on MY list lol.

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  16. updated the layout again. there were a few misplaced components and gain 1 wasn't connected as it should have. should be good to go now.

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    1. glad I've just caught this, populated the board let night but gone with the old 19 x 20 so will get creative with the wiring of the pots. nothing else changed from what I can see?

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    2. Hey Zach!
      It could still be a 20x19 layout by eliminating row A if you want(not a major difference).
      The 2nF - 12K connection on row E-17/18 can be lowered to G-17/18 (the 2nF would span 3 rows).
      Add a cut on G-12.
      D2 should go from row E-5 to B-5 (instead of A-5).
      Now you can lower the 10uF cap, D1, IC1 (and their cuts) and the +9V connection 1 row down.
      It could also become a 20x18 but you would have to move more components on the right side (again, it would not make much difference)

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  17. Hi, made this one using a TL1044s and biased all the J201's to as close to 9v as I could, sounds bad ass, loads of low end boarders on fuzz at higher gain settings. can consider this one verified

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  18. Did someone make work the updated layout 20x20?

    I also found this one older pretty similar layout: http://guitar-fx-layouts.42897.x6.nabble.com/file/n18809/1485.png

    This is the the basic schematic: http://guitar-fx-layouts.42897.x6.nabble.com/file/n18170/destijl%2520revision%25202.jpg

    You can read the thread here: http://guitar-fx-layouts.42897.x6.nabble.com/Silvertone-1485-Twin-Twelve-td18170.html

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  19. The 20 x 20 worked for me. I tested it a few weeks ago but haven't boxed it or played with it since. I think I was getting ~15V with the IC I used, so I biased to half that.

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  20. Thank you.
    I'm still thinking about if I have to build this pedal, of course I like it, especially if it really sounds as the original.

    Anyway, I should to get an ICL7660S. Your 15v seems a bit low. I assumed to get at least 17v.
    Do you remember the IC you used? Did you check some possible mistakes?

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    1. It's a Max1044 from Tayda. I was measuring at D1 before. I checked it at D2 and it's about 17.5V.

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  21. Need some help. I built it but volume is low. All the way up is just above unity and bass control is practicly useless.

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  22. Hello. I can't rule any Voltage using the trimmers. They just lower the voltage from let's say 17.5 to 17, it doesn't go lower than that. What could be wrong?
    Thanks!

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    1. My guess is wrong value trimmer, bad jfets, or something is connected that shouldnt be. Try different jfets, then double check your cuts and links, then check your trimmer values.

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  23. Thanks for your hard work on this great layout. I do have a small issue and it is concerning the bass knob, it has very little affect? I built two and both behave the same. Is there anything I could try to get more bass action?

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    1. I have the same issue. the bass is not as powerfull as the videos, and the bass pot doesn't boost the bass that much...

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