Thursday, 14 June 2012

Wampler - Tweed '57


Brian Wampler has alway made cracking pedals - the Tweed '57 is no exception. It's another pedal based around the jfet "amp emulation" technique that is frequently employed in this current era of overdrive pedal design.

Here's the description from the Wampler website:

"Brian’s work on the Wampler Pedals Black ‘65 left him grinning. Finally, after months and months of work, he’d nailed it. A pedal that can conjure a whole realm of classic tones with a few turns of the EQ knobs; a pedal that works equally well as a dedicated overdrive inspired by great, vintage Fender® amps, or as a “preamp” or “tone shaper” that, when put at the end of your signal chain, just before your amp with the gain set low, can make any pedal before it sound and respond like you’re running it through whichever favorite amp of the time period you dial it in for. A genuinely passion-driven homage to some of history’s greatest amps! Yet that accomplishment couldn’t be the end. History, after all, goes farther back than 1965, and so does the story of great tone.
Brian Wampler is a confirmed tone fiend. He has to be, to make the kind of excellent sounding and great playing pedals Wampler Pedals is known for. He knew that his work on the Black ’65 would need to be followed up by another pedal to make the classic Fender® amplifier inspired Wampler Pedals family whole. When you go back in time, past the era that inspired the sound of the Black ‘65, you find yourself in the land of tweed, where raw, driven sounds offered guitarists new possibilities that they had never heard before, sounds that have found their way onto historic recordings. Creating a pedal that could do for the tweed amps of the mid to late 1950s what the Black ’65 does for its amps would not be an easy process, but Brian has never shied away from a challenge!

Enter the Tweed ‘57, a pedal inspired by historic Fender® amps and their magic tone, a pedal which offers a wide palette of sounds and includes several features that you’ve come to expect from Wampler Pedals as well as some surprises Brian’s cooked up just for this pedal! With a full three-band EQ voiced carefully to let you get a wide range of tones from your amp, the Tweed ‘57 is not limited to trying to achieve one particular sound. And thanks to the fantastic “Input Simulator” switch, you’ve got flexibility and control just as you’d expect on an amp from that period, with Normal, Bright, and Linked input options that cooperate with the EQ and gain adjustments to give you control that is easy to use and rewarding to play with. The pedal’s dynamic response is extraordinary, and the overdriven tone is amazing.

Play the Wampler Pedals Tweed ‘57 and you’ll understand exactly what inspired Brian to create this pedal, with a sound so characteristic and raw. Worked to perfection for his setup and yours, we bet after you experience this pedal’s historic rhythm and timeless, leaping-off-the-frets lead, you’ll be grinning, too. "

And here's a demo video for you;



Here's a picture of the guts (note the image is reversed ready for tracing);


And, thanks to some cracking work, here's a schematic, pcb transfer and layout (the schematic parts numbers tally to the pcb layout) from lukatosh;





If you're interested in how these pedals get traced out from their pcb layouts check out the freestompboxes.org thread here. It's a great example of how it's done!

16 comments:

  1. Somebody have the layout of the WAMPLER-plexitone???
    Thanks a lot great site!!!!!!!!

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  2. Gonna have to buy one. Email me if you have one for sale.

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  3. This comment has been removed by the author.

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  4. Not sure if this is a mistake but Q8 is 2N3904 and Q9 is 2N3906 one is npn and the other pnp???will that work,also this pedal only has 6 transistors so it should say Q5 and Q6 ???

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  5. Hi, I just quite wonder were does the "LED" in the schem and PCB layout go? It only has an encircled "x" mark to which I suspect, to ground? Am I right?

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  6. Where it has r6 10k ,then led - on the pcb and the schem

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  7. Thanks, Briggs. So this is just a Deluxe in a box, literally. The schematic is the same except that the tubes are replaced with JFETs. Good sound though. And, having it in pedal form allows you to crank the pedal to get that sound.

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  8. hi does anyone has the .sch and the .pcb files?? i cant see very the the layout

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  9. Why are Q3 and Q4 in parallell? Same for Q5 andQ6. Seems like one transistor would do the job (provided resistor values on source/drain are devided by 2). Mysterious

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    1. It's a configuration called a mu amp. Check out www.muzique.com or google

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    2. No, it certainly isn't a mu-amp! The mu-amp uses two FETs in a totem pole type configuration, one standing on the top of the other acting as its load, not side by side with it as here. It's just as Anders says, two JFETs in parallel. There is no reason why that shouldn't work but the two FETs will have slightly different characteristics so it will mean a degree of randomness creeping into the overall sound. That may be what they are after I suppose.

      I am actually more worried about the setup of Q8 and Q9. I can't for the life of me see how that can work in any good way to stabilise the line. With the collector of Q9 not connected into the control circuitry of Q8 the supply line voltage is actually undefined.

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  10. I would also ask here, can anyone confirm that J201s are REALLY what is used in this and other Wampler pedals reported online? Other than the out of place nostalgia of harking back to germanium days when circuit design was c**p and components were even worse, the choice of a BJT is virtually irrelevant in any decent low voltage low current circuit no matter what anyone says. However, with the massive spread of parameters within any particular type the choice of JFET is very significant to the outcome of the circuit. They don't sound different but their DC levels will be all over the place which is a factor.

    Also, input overload margins can go from a couple of hundred mv to 2V with even common types for example. That is crucial as to whether you are making the distortion of the first stage a design factor or setting up a clean buffer with the other tonal stuff done in later stages. The J201 is not a particularly good choice for that aspect alone.

    So, is it marked as a J201 in the pedal or is it an assumption somewhere that that must be what gets used because it's always what gets used?

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    Replies
    1. Looks like the board itself says "J201" (backwards, obviously)

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