Reduce gain on express

[JammyDodger]

I simply deleted the bypass cap of the second
stage cathode resistor,that did it for me,
now I can turn the volume to 11...

So this is the 22uF Cap (C7)? How does that drop the gain?

Cheers, Mike

[two tone]

Mike,you can calculate this here:

http://amps.zugster.net/tools/triode-calculator

you drop the gain about -10dB
by removing this cap

[PlinytheWelder]

You could also make it switchable...

[C Moore]

I simply deleted the bypass cap of the second
stage cathode resistor,that did it for me,
now I can turn the volume to 11...

That would certainly do it. Was a change in tone/feel of the amp noticeable ?

I wonder how a 5751 or even a 12AY7 in V1 would work in an Express.
It seems to me that this amp just has too much gain/distortion , or said another way too little headroom, for most people who build it.

less gain,smoother tone,
no more need to worry which bright cap to use..
turn up this volume control

I just got an Edcor OT from RJ that I will be installing soon (maybe sooner after reading this) So you did not notice a significant loss of bass or lower mids....nothing like that eh? I may have to give you a finders fee.....

[M Fowler]

I have not used the Edcor in an Express but did in the Rocket and Rocket Reverb 80watt and there is a tonal difference with the Edcor. I think a more rich high, mids and deep bass.

But what do I know

[steviea55]

V1 and V2 with 12AX7's and a 12AU7 in the PI(V3) will tame it. I use all NOS for the pre and Simens (RAF) for the power tubes.

[bigbeck]

I have not used the Edcor in an Express but did in the Rocket and Rocket Reverb 80watt and there is a tonal difference with the Edcor. I think a more rich high, mids and deep bass.

But what do I know

I used a stock Edcor CXPP30-MS-5K in my Express. Sounds killer to me! Since it's a Hi-Fi ot, you could easily get away with the slightly smaller 25 watt unit.

But WTF do I know,too.

[M Fowler]

Bigbeck sounds like you know a lot if you used an Edcor in your amp

A project down the road will be an Express built with all Edcor trannies/choke. (rjguitars)

Perhaps the Hoffman layout but I need to talk with Doug Hoffman about how his turned out. Or PCB just for something wacky.

EDIT Doug said he didn't do that layout or amp so must just be called the Hoffman layout due to the style the board was layout in which is Hoffman style[/b]

Oh and can caps all the way baby!

Top coat wire as well.

CTS pots.

Going to figure out the coupling caps later, it will be a mixture of various types.

[rooster]

Richie - Really? That will knock the volume back how much? 3db? I didn't want you to think I wasn't listening to you, BTW, and I'm back to check this thought out. I can see the feedback decreasing, going to 200K, and the amp getting a little woolier, and sure, maybe a little more perceived volume. But going from 100K to 50K would reduce the volume noticably?

I probably would not want to change the feel of things so I would never do this to my Express, but honestly, I have never been interested in giving an amp more feedback than a 20 to 1 ratio. This seems about the max for my tastes. But, hm, here you suggest 10 to 1 and I have never even thought about this or tried it. If you have, besides the volume drop you suggest, what else did it do the the Express circuit?

Eh, yeah, just curious enought to ask, BTW, but not enough to actually try it I guess. So?

[Richie]

I was looking through some things, and saw that i didn't reply to this question. Even though its been quite a while. I miss things alot here sometimes.

But what changing the feedback resistor from 100k to a 47k or 27k. It will stay cleaner on the amp volume control. or in other words, the gain won't come on so fast,it will come on slower. Turning up the volume control the amp will stay cleaner,or seem to have more headroom campared to the way it was before the change. But it won't really reduce the volume,just gime a little more clean on the volume control. It will still have gain to it as its turned up more.

[M Fowler]

Richie how about keeping the resistor as is but the feed is attached to a different tap on the OT.

[Richie]

that can work too. I just usually change the resistor.