"Thunderchief" -- Comments on this sound clip

[jimosity]

I just got done building the 'Thunderchief' from ROG...I set the bias by DMM on Q1, then tuned the rest by ear.
I know the idea was that this guy was supposed to emulate a Marshall with a dimed out EQ section, but I'm not sure what I am getting is right.
It seems like it's lacking bass / low end and maybe has too much sizzle to it...
I know I could incorporate an EQ section, but it seems when I was tweaking the J201's, Q3 had just a little bit of play in the 'safe' zone that gave the tone a little more 'mid shaping' for lack of a better way to describe it....
Towards the end of the clip, you'll hear where it has more 'mid shaping' to the tone, that's me playing with Q3...then it seemed like Q4 had far more tone shaping to it almost at any range, almost made it seem like I could replace the Q4 trim pot with a 100k pot to act as a tone control.

My question is, for those of you that have built this thing, does the sound clip sound about how this circuit is expected to sound?

It still seems like I'm not quite getting as much volume out of it as I am expecting...just lower enough to make me think that *MAYBE* I have something wrong...

I recently built the Dr. Boogey and it crushes this guy, which leads me to believe that either I have something wrong here or maybe I just don't dig this circuit as much as I thought I would.

Would putting in a tone stack give me any better results ya think?

Here's the clip

Stream it.
Download it.

[Baktown]

Maybe my ears are as "sensitive" as some peoples, but I think it sounds awesome.

Rick J

[Baktown]

I meant to say my ears "are not" as sensitive as other peoples.  Oops! 

Rick J - I type 3 words per minute, all of them....

[dschwartz]

it sounds fine..
try changing the fets..test a bunch of them until youré satisfied

for the tonestack you could try a BMP tone control + presence control (see AMZ BMP presence control) and a fet recovery stage (like a fetzer valve or amz fet boost)

anyway..dr boogey kicks its butt anytime...

[m-theory]

You're right...it sounds nothing whatsoever like the amp that it's supposedly emulating.  Very mushy/fizzy/buzzy, undefined, inarticulate, harsh tone.  I'd definitely try some different FETs.  I've gotten dramatically different results from different FETs in BSIAB builds. 

[Meanderthal]

 Mine didn't have much bottom end, but it did emulate the EVH sound, which doesn't have much either.

I had quite a time getting the fets to bias up. Which led me to wonder if you tried monkeying around with the bias trimpots by ear, or just went with the 4.5v? Minor adjustments might get you a fuller sound.

[jimosity]

I only tried the MPF102 in Q1 and that took away more gain that I wanted it to, so I put the J201 back in.
I did bias it via meter on Q1, but didn't check Q2-4 with a meter, just by ear.
Seemed Q1 was very sensitive to get it in the right range whereas Q2-4 had a lot more room to work with.
I probably tweaked on the trim pots for a good hour, never really getting much better than the sound clips that I posted.
I'll probably try the BMP tone stack with it and see if that gives it any more ass.   It's like if it had some low end/bass and a tad bit more gain along with some more control on the mids, it'd be cool.

[stm]

I'd suggest you try Thor instead.  Please note however that Thor was designed as a medium-gain pedal, so if you expect the tone of a high-gain pedal you will be dissappointed.  Nevertheless it overcomes several flaws of the Thunderchief.

In general, JFET pedals rely heavily on the particular characteristics of the JFETs among the different stages.  The JFET type and characteristics are crucial to obtain a repeatable tone, and as it has been already mentioned, swapping devices with the same P/N will produce audible effects.

Regarding Thor, I can add that:

1) The Bright option has been said to be too bright for some people, and a 100k, 220k, 330k or 470k resistor in series with the switch and 470pF cap helps to fine tune this to the particular needs of the user.

2) The Bottom switch introduces a big, fatty 12 to 15 dB boost in the 125 Hz area, thus its effect should be pretty evident if it is operating properly.

3) The first input stage NEEDS a 2N5457 device with a Vp around 1.4V-1.8V or so.  An MPF102 will have too litlle gain and sound duller, where a J201 will have more gain but will compress too much.  This stage can be biased as indicated in the schem, or by ear for best overall sound.

4) In a similar fashion, the second stage NEEDS a J201 to have enough gain.

5) Last but not least, the final stage formed by Q3 and Q4 NEEDS 2N5457's as well.  If Q3 and Q4 are reasonably paired the output will self-bias close to Vcc/2, or between 4 and 5V.

Regards.

[ConanB]

Good info there Sebastian, I have a Thor PCB ready to go and am just waiting on some 5457's to get started. Was considering a Thunderchief instead but glad I went with Thor.

[arawn]

Dude that sounds awesome!! I think it's great, Besides what if it doesn't sound just like ______ ? If it sounds good