Really Bright!

[PlinytheWelder]

I didn't realize that I had one resistor value wrong on mine until I checked all my voltages, so that's a good thing to try.

Since I dislike silver mica caps I used Wima Polypropylene FKP2 caps on the bright switch. I think they worked out well.

http://www.mouser.com/catalog/641/usd/853.pdf

[WhopperPlate]

IMO Celestion Vintage 30's are painfully bright with most amps. Probably doesn't help your situation.

[Gibsonman63]

There are a few oddball readings here. I'll retrace the circuit again. All voltages are relative to ground except for the heaters.

V1B seems a little off.

BTW, the voltages in the build guide are a little different than the voltage chart.

[Gibsonman63]

Change the 10k/470 tail/cathode resistors to 39k/1k. That'll give you a lot fuller lows to balance out the tone.

I didn't have a 39K, so I stuck a 33K in instead. This is definitely a step in the right direction, maybe even a hair too far. I am going to undo my other mods and maybe back down on these values a bit.

I am able to play with all three tone knobs around the mid position with the bridge pickup and am able to play with the bright switches now, but it does seem like I lost some clarity. I guess everything is a compromise.

I'll take a test drive at band rehearsal tomorrow and see how it fits in the mix.

[Jackie Treehorn]

Great! I've got a couple thoughts on your clarity observation: I would still try 39k, as the effect of this mod is not really "linear." For example, it seems like values in the mid-20k's sound really mid humped, almost mesa/dumblish. Appr. 39k-47k is where it sounds really balanced and you get the chime to the tone.

You might try reducing the NFB resistor. 68k works really well for me, but nothing beats trimming it by ear while working the volume knobs with the guitar you use. I suspect this might be the crux of the clarity problem.

[RJ Guitars]

Your like me build a TW but tune it to what you want and for your own purpose, very good, Ken would have liked that. Mark

Barbaric Sacrilegious Heathen!

(And one of my favorite influences)

[M Fowler]

Thanks rj you must have recognized my Viking blood line.

[Gibsonman63]

I put a 39K resistor (measured at 40.1K) in place of the 33K that I had on hand. To me, it added just the right amount of chime back to the amp. For my SG on the bridge pickup, it sounds full and wonderful with all the knobs about half way and with the bright switch engaged in either position. I can actually use the bright switch now!

Thanks to all.

[M Fowler]

Those PI values are Rocket values not wonder it sounds so pretty.

[Gibsonman63]

I changed the coupling caps and bright caps with Polystyrene caps today. The difference is not huge, but there is something there.

Now that I have some hours on the amp, it keeps sounding better all the time. I am not sure if my ears are adjusting to it or my playing. This amplifier is definitely a different animal from anything else I have played.

[PlinytheWelder]

I changed the coupling caps and bright caps with Polystyrene caps today. The difference is not huge, but there is something there.

Now that I have some hours on the amp, it keeps sounding better all the time. I am not sure if my ears are adjusting to it or my playing. This amplifier is definitely a different animal from anything else I have played.

The electrolytic cathode bypass caps definitely break in over time. I've changed
enough to expect a "ratty" atonal low level fuzz at first that goes away after a few hours of use.

Just like when forming PS electrolytics.

[jaysg]

I am playing a '79 SG, completely stock.

With my Liverpool, at no time are the tone knobs on 10...more like 2 to 6. Same usually for the volume knobs. Glen has some telling comments about the brightness...originals are bright...not as bright as a lot of clones, but he talks about KF building little cap switching boxes that go across the input to kill highs.