Hail to the Chief (Thunderchief)!

[powerplayj]

Wow! What a nice little build.  I just bought a Neovibe board from GGG, etched 6 pcb's (Big Muff, Mr. EQ, Dist+, Thunderchief, Dr. Boogie, MOSFET boost,) and ordered components for all, minus the switch and enclosure.  The Thunderchief was the first project and a fairly easy build except for squeezing in the trim pots but who knows, maybe I made the pcb's too small. 

Any way, it sounds killer and in many ways quite similar to the BSIAB2.   I sort of miss the tone control but I might try the mods from ROG to give it a bit more flexibility.  I will say that it is a bit less noisy than the BSIAB2 and seems to respond better to pedals before and after it.  Whoever had the tip of placing a tubescreamer before the Thunderchief was right on the money as this seemed to really make the pedal quiet (especially at high gain).  Too my ears, it isn't quite as middy (upper mids) as the BSIAB2 and has more of a lower mids raw tone at higher gain.  Just to give an idea of its range, at lower gain I could get some good Trower tones (think "Day of the Eagle") with single coils and at higher gain with a bridge humbucker the first thing that comes to mind is the Kixx album "Blow My Fuse".

Chain it to the MOSFET boost I built and it really sears.  Much has already been said about the MOSFET boost so I want gush too much about this one other than saying it will replace my Rangemaster on my board.  It's so versatile with pedals and both amp channels.   

Anyone performed the Thunderchief mods?  I've only seen a thread or two with comments about these.

[Mark F]

  

Anyone performed the Thunderchief mods?  I've only seen a thread or two with comments about these.


[/quote]   I built the Thunderchief using 2N5458's but couldn't get Q3 to bias. I followed the suggestion on ROG's FAQ & replaced the upper 4K7 source resistor with a 1K but it still wouldn't bias. Anyway by the time I got done I had to eliminate both 4K7 source resistors & it biased almost exactly to ROG's specs. I also added the tone stack. I tried both 5458's & J201's in the buffer position & it didn't matter which one was used. I didn't think it would. I was pretty pleased with the results using the 5458's. Before I used the 5458's I built the circuit as prescribed with J201's & I had no problems biasing. It's quite a bit tamer with 5458's which is what one would expect.   

[erick4x4]

 

Anyone performed the Thunderchief mods?  I've only seen a thread or two with comments about these.

I built the Thunderchief using 2N5458's but couldn't get Q3 to bias. I followed the suggestion on ROG's FAQ & replaced the upper 4K7 source resistor with a 1K but it still wouldn't bias. Anyway by the time I got done I had to eliminate both 4K7 source resistors & it biased almost exactly to ROG's specs. I also added the tone stack. I tried both 5458's & J201's in the buffer position & it didn't matter which one was used. I didn't think it would. I was pretty pleased with the results using the 5458's. Before I used the 5458's I built the circuit as prescribed with J201's & I had no problems biasing. It's quite a bit tamer with 5458's which is what one would expect.   
[/quote]

How much did the tonestack change things? I love my thunderchief, and at high volumes with a good amp it sounds great, but I often feel like its bright. I would love to be able to roll off highs, and boost or subtract mids. Did the tone stack give a lot of flexibility? I tried tweaking the low passes, but truth is I own a marshall (I use this pedal when I don't have my marshall), and I find the "all knobs on 10" is also bright on my marshall, so I am sure the tonestack should help me but was curious. I also want to try the presence knob, I never use presence all the way up on my marshall.

Also, I also tried changing the upper 4.7k to 1k, and still couldn't bias it. When you say "removed" did you put a jumper in or just use really small resistors in place of both? My Q3 is at 4.5v but the Source is still 2v and the gate is 1.5v, which does seem to function, but I wonder if it is ok?

[Mark F]

How much did the tonestack change things?

I found it to be quite flexible with the tonestack. I was able to get it quite muddy up to brittle highs.

Also, I also tried changing the upper 4.7k to 1k, and still couldn't bias it. When you say "removed" did you put a jumper in or just use really small resistors in place of both? My Q3 is at 4.5v but the Source is still 2v and the gate is 1.5v, which does seem to function, but I wonder if it is ok?

I replaced the 4K7's with a jumper. I was able to get it to function with the 4K7's but it was gated & it looked it on a scope. I haven't tried the presence control yet. I also added the 250uF bypass cap on Q1 to simulate the other channel. This thing is still on the board so I'm gradually trying "variations" as time permits.

[rockgardenlove]

I've got one of these half finished on PCB too, gonna finish tomorrow probably.  I made ROG's one, I'll tell you how it goes.

[powerplayj]

I've got one of these half finished on PCB too, gonna finish tomorrow probably.  I made ROG's one, I'll tell you how it goes.

Cool!  I want to try the variac, lead/normal channel and normal/bright input mods next.  If the lead/normal channel mod has a substantial difference in tone, I might connect that to a 3PDT switch.