Wampler - Tweed '57  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
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Ben N
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Post by Ben N »

It really is a heavily tweaked, much improved variant of a Blues Driver: Two JFET diff-amps with a Fender TMB tone stack sandwiched between. Brian did what Boss should have done, in using the tone stack, instead of making its values fixed and tacking an ineffective tone control on at the end. There are no clippers or pre-stack buffer, the diff amps are carefully tuned, etc., etc. But at core, that's the topology. Nice job, Brian.

Has anyone compared this to the ROG Azabache? They seem to be targeted at the same sonic territory.

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The G
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Post by The G »

There's no differential amp in the Tweed, the JFET are in parallel (they have all the pins tied together, including the gates), which should - among other things - bring the noise down by 3dB. If the JFETs are not paired, some interactions should occur between them. You could take out one JFET of each pair and it would not sound very different.

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grrrunge
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Post by grrrunge »

Intripped wrote:
Sweetalk wrote:1.5n bypass cap after the first stage??... it's that ok?
it sounds strange to me too, but you can clearly read the value of that cap in the pics posted
...camouflage? 8)
As i see it, C15 forms a high-pass filter with R16, R23 and the gain pot.
With a capacitance of 1.5nF and a total resistance of 591KΩ, you get a break frequency of 1/(2·π·1.5nF·591KΩ) = 179.5Hz - nothing criminal going on there ;)

raising the value of C15 gives you a lower break frequency:
2.2nF -> 122.4Hz
3.3nF -> 81.6Hz
4.7nF -> 57.3Hz
10nF -> 26.9Hz
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rwdavis2
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Post by rwdavis2 »

Just wondering if anyone ever produced a layout where everything is readable. Much of the lettering in the lower middle/right is scrambled.

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POTL
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Post by POTL »

Hey Tell me what is the advantage of this combination of transistors (Q2 + Q3 & Q4 + Q5) over single transistors or Mu Amp
Do I need to match the transistors
If this is what value
The new version is capable of operating from 9-18 volts

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sanfi4u
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Post by sanfi4u »

POTL wrote:Hey Tell me what is the advantage of this combination of transistors (Q2 + Q3 & Q4 + Q5) over single transistors or Mu Amp
Do I need to match the transistors
If this is what value
The new version is capable of operating from 9-18 volts
Initial idea was to lower transistor gain. As I understand no need to match them. You'll find more info on the topic in the following threads:
https://www.freestompboxes.org/viewtopic.php?f=44&t=2674
https://www.diystompboxes.com/smfforum/ ... ic=17513.0
https://www.diystompboxes.com/smfforum/ ... #msg513996
BTW, where did you get the new Wampler Tweed '57 Release 2016 can be powered with 9-18VDC? It's not in the manual. Do you have gut picks of the new pedal? Is it SMD based now?

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