Dropping gain w/o affecting tone

[Jana]

180k from b+ and then a 33k to the plate would not be much change at all. swap them around and the change should be significant. Do you understand what is happening with the plate resistor?

[iknowjohnny]

I just realized that ! Doh ! Spaced...I'll try it again.

[billyz]

The spilt load plate resistor switch as in the Komet is what you are doing. Use what ever values you like the sound of.

see my attachment. sub in the values of the resistors you want ie instead of 82k use 180K and for the 22k try 47k (40k would be ideal) . or the closet you have on hand.

[iknowjohnny]

Worked great. definately a great way to drop gain w/o ruining the tone, thanks ! I actually only had to do one plate to get the gain reduction i needed. As for billy's switch idea....i'm way ahead of ya ! I was planning on a pus/pull pot to do that.

[billyz]

Thanks for the nod , but the switch was not my idea. It was first used I believe in The Komet amp. and pretty well documented here.

[Aurora]

That green wire should be on the other side of the 82K....
Not much sound coming out of B+ , - I hope......

[iknowjohnny]

I didn't go by that drawing. It's so simple you don't need a drawing. My mistake was truly just a "doh !" moment, not a matter of not understanding it. I just spaced while doing it. In any case i have it almost balanced with a 100k and a 120k, the 100 coming off the plate. i think i'm still gonna reduce it more tho. Probably a 56k and a 150k. I think that will be just right.

[pureoldsound]

deleted

[billyz]

Hey, does this look better? I grabbed that picture and did not notice it was wrong. I tried to correct it does this look right?

[roberto]

Billyz, now is right.
In attachment you can see some improvements of the split load with modified frequency response. Very interesting!

[iknowjohnny]

It would be awesome if there was a similar app to duncan's tone stack calculator but for that ! why is the split load plate anode not more common i wonder. It;s a great way to control gain. I even $hit-canned my voltage dividers and the amp sounds a lot better, and it sounded good before. this is one trick i'll be using a lot.

[iknowjohnny]

I have another related question. How would switching this on the fly work as far as pops? Would there be a loud pop? I'm definatly putting a gain switch in but i'm thinking this would be a great footswitchable gain boost in this amp.

i can't believe how much better this amp now sounds with the voltage dividers gone ! I don't know why, but they really held back this amp's potential and it now sounds what i don't even hesitate to call phenomenal as high gain amps go. This is a great mod. Not just sound, but even more importantly FEEL, which has gone thru the roof. Good god this thing is SOOOOO fun to play now. I gotta thank you Jana....great suggestion !

[RB]

Komets have a manual fast/gradual switch that switchs between the plated loads. Even better I believe Allyn Meyers has/makes/sells a foot switch controlled solid state switch he installs in his amps that will do just what you want.

[RB]

Komets have a manual fast/gradual switch that switchs between the plated loads. Even better I believe Allyn Meyers has/makes/sells a foot switch controlled solid state switch he installs in his amps that will do just what you want.

[Jana]

well, the tone stack calculator can be used in quite a few ways other than intended. I find a stack that has a similar set of connections that I want and then insert 1p for caps that I don't want there, 100M for resistors I don't want, 1 ohm for resistors I want to be a wire, 1000u for caps I want to be a wire. Most times I can create a circuit that does what I want.

My guess that this (the splitting the load) isn't done more often is because, A. Leo or Jim didn't do it so it isn't an option, B. it is in a place where there is a couple hundred dc volts, that makes it a place for failures if relays are used (Leo and Jim didn't have access to the solid state switching options that are available now), and I am sure that there will be some serious pops if this is switched with the amp on (a relay or toggle).

Since you are in the experimenter mode, you can be our guinea pig, how about this: take a coupling cap off of each node, say one from the junction of the resistors and another from the plate. Have a pot or voltage divider for each coupling cap. Then switch the signal going to your next grid. This could open up some options for you. As you probably figured out, you need a trebly signal for a good distortion or it gets all muddy and flubby. That sound is very icy picky when used for a clean setting, not really a Jazz players dream! Well, if you use a small cap for your high gain setting and a bigger cap for the lower gain one, that could help to compensate for that.

I never tried this so it's up to you to see if it works. If it does, cut me in on the profits, lol.