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previous: hasserl Re: Got my Clubman clone going -- 6/30/2003 12:35 AM View Thread

Continuing Clubman Concoctions

7/7/2003 5:47 PM
Continuing Clubman Concoctions
Catchy subject line, eh? :) Anyway, I've reworked both the biasing of the 6AU6 pre-amp pentode and the power supply. I rewired the first leg of the B+ rail back to the 1st filter cap stage and out to the OT center tap, but lowered the B+ with zener diodes on the PT center tap, and I also went back to the 5Y3 rectifier. The B+ is now ~408v (@ 111 line voltage, which is fluctating a lot lately, from 111 up to 115). This puts 406 on the plates and 395 on the screens. This gave quite an increase in available volume, but also makes it a little punchier at mid volume settings, not quite as soft. I'd like to increase the B+ more, but am afraid I might send the OT into meltdown. :( I changed the 6AU6 plate load resistor to 100k, which decreased the gain from that stage and helped clean up the distortion a bit.  
I can say there are definitely very good tones in the amp, but there are also a lot of harsh ones. I played both single coils and humbuckers thru it, and it needs lots of tweaking with the different guitars, and for different songs. I can't just set it up to one setting and then just tweak the guitar controls, I also need to tweak the amp controls for the different songs. This seems moreso with humbuckers than with single coils. Clean tones need the volume rolled back to about 10 o'clock to 11 o'clock, dirty tones need it up to 12 to 1 o'clock, and above that it gets very distorted, which can be a good thing too! But it is hard to dial in a setting where you can go from a nice clean tone to a good dirty lead tone with just the guitar's volume control. If the amp volume is turned up enough to get the good dirt, just rolling off the guitars volume won't clean it up enough, it remains gritty, which can sound harsh. Turning the amps volume down to clean it up lets it sound nice, but then you can't just crank the guitar's volume control up to get the dirt. So, I've still got some more sorting out to do. But it's much better, and it's now quite a bit louder.  
I'm beginning to think part of the problem is the placement of the volume control. Normally you see the volume control just after the first gain stage. In the Clubman it is after the second gain stage before the PI, where some amps put the Master. So the first stage is always slamming the second stage full on with no attenuation (except for the Bass and Treble pots). I'm thinking that a dual pot wired up to attenuate both stages at the same time might help.

D. Hiatt Collins Volume control placement -- 7/7/2003 9:02 PM