Another fun thing to do, which is great to add touch response to a hard amp, is to change the 470 ohm screen resistors on the output tubes to say 2200 ohm or even higher.
I don't build anything with less than 1K ohm in the tube position here, helps with the tube life too.
2k2 and above will add some squish. I have used it to add touch response to cold Marshall circuits before.
I have a 2.2k screen resistor on the power tubes in both my TOS builds. It gives the amp a little more of a compressed sound to my ears. Geezer prefers a smaller value.
You can also use a 5v trannie and add a rectifier tube IF you have room on the chassis and want to try that.
Hey Mat,
I'm interested in the effects of the larger screen resistors.
So if you try that, please post your impressions of the change.
Also, I'm looking at the Tweed OD schematic and see it uses 2.2uF bypass caps.
If you increased those to Fender specs, 25uF, would that help loosen the bottom?
Another fun thing to do, which is great to add touch response to a hard amp, is to change the 470 ohm screen resistors on the output tubes to say 2200 ohm or even higher.
I don't build anything with less than 1K ohm in the tube position here, helps with the tube life too.
2k2 and above will add some squish. I have used it to add touch response to cold Marshall circuits before.
I have a 2.2k screen resistor on the power tubes in both my TOS builds. It gives the amp a little more of a compressed sound to my ears. Geezer prefers a smaller value.
You can also use a 5v trannie and add a rectifier tube IF you have room on the chassis and want to try that.
With respect, 10thtx
The tranny could go in the place of the choke. I have a dream of implementing a two tube reverb also on this build. Then I woud have to install an extra heater tranny also.. dont know.. I just purchased holy grail nano. Will try that on the active loop.
Structo, I will let You know how the 2k2 vs. 470R will sound/feel on the build.
mat wrote:I have a 50W 124 (built in dlator) style build that has evolved many versions to date (actually my test bench build). Latest is I built 10thTX and geezers Tweed Overdrive Specials pre amp into it. At lower volumes it is really good sounding amp, at band level it is way too tight for my playing style. Side by side with the previous builds (nonHRMskyline and 2555) it is too tight sounding.
How could I achieve more loosen power amp section? I tried Delta Pro 12A but prefer RWB on this amp. I'm afraid the PT does not handle tube rectifier. The build has 5 novals and two octals. Overall voltage drop ?
Any tips ?
Thanks,
what r the value of grid resistors on the power tubes? Higher makes softer, also the bias resistors? Lowering from 220K to 200K softens up well too
Structo wrote:Hey Mat,
I'm interested in the effects of the larger screen resistors.
So if you try that, please post your impressions of the change.
Also, I'm looking at the Tweed OD schematic and see it uses 2.2uF bypass caps.
If you increased those to Fender specs, 25uF, would that help loosen the bottom?
Thanks everyone for the suggestions. I had today time to put in 2k2's in place of the 470R's and that change made the biggest improvement so far.
I will test again with proper volumes next sunday. Will report back.
