Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: plexi50 on June 23, 2011, 04:01:10 pm
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I have a Peavey Windsor Studio amp i am attemting to bypass the attenuator using a DPDT switch. 3 wires. I think i have already wired the switch wrong
My brain just went blank again. Does anyone have a diagram or can show me where the wires will connect to on the switch? :w2:
I was thinking the last pic circled in red: The amp board wires are just laying there in place on the switch
I have not soldered them to the switch yetXXXXXXXXXXXXXXXXXXXXXXX all that
This is simple and yet i have a brain freeze. I dont need a DPDT switch do i?
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If the black wire is the ground wire then it goes directly to the sponge.
The switch only bypasses red and yellow wire.
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Black is the ground wire. Black ground solderd to the spong terminal. Like so?
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Actually, now that I think of it, you may need to break the ground connection and bypass the red and yellow wires when the sponge is off the circuit.
Like so:
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This is what i came up with. Attenuator OFF: Left terminals are Yellow & Red wires switched together
Attenuator ON is right terminals fed by Yellow center and Red wire buss feeding the Sponge
Whatcha think. Im pretty certain this is it. I cant spell CAT today. The last pic is from a thread i found where they were just removing the attenuator all together to get a fuller sounding tone. The attenuator is suppose to be sucking a lot of tone in this amp. So i wanted the bypass option to keep it stock and have the ability to remove it from the circuit at will. Havent hear what it will sound like just yet. Made 3 little changes to the preamp. Removed C40 cap at the input grid, C51 at another preamp grid and a bass robbing 470n cap on C52
If im wrong i will know shortly. The last pic has the ground wire going straight to the chassis with the attenator removed. Your right i may have to come up with a ground switch here but i would think the ground on the sponge may have a ground chassis connection from the mounting of the Power Sponge cage to the chassis
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I think you're good to go.
That is what I was thinking first, but then for some reason I thought that it would leave the sponge parallel with the speaker which it doesn't do because it breaks the other two connections to the pot (or L-pad).
Sorry about the confusion, I shouldn't post anything after midnight. :sleepy2:
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Thanks VMS for your help and diagram. Half the time i dont type what i mean or have trouble explaining certain things
Well the switch works,the attenuator works and the bypass works. But i dont hear any difference at all in volume or tone
It got the idea to do this from a thread i found yesterday morning after buying the Windsor for $180.00. I could not resist
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Well the switch works,the attenuator works and the bypass works. But i dont hear any difference at all in volume or tone
How can the attenuator work if you can't hear any difference at all in volume?
Brad :dontknow:
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Well the switch works,the attenuator works and the bypass works. But i dont hear any difference at all in volume or tone
How can the attenuator work if you can't hear any difference at all in volume?
Brad :dontknow:
The attenuator is working and the bypass is working. There just isnt any difference between the attenuator at full throttle and the attenuator in the bypass mode
There was a thread that stated the attenuator bypassed produced a louder amp and different tone. Im now thinking the thread was not stating facts rather wishful thinking
I moved the attenuator to the other side of the amp to have full time access to the preamp and power tubes without having to remove the Sponge base. I put a West Labratories 12" speaker in it that is identical to my EV SRO 12" 1974 speaker. The speaker itself weighs more than the entire amp twice over. I have a 1962 RCA BP 6L6GC power tube in the octal. I replaced the tiny tone stack caps with Xicons and well as the treble peak cap with a silver mice 250pf. I rebiased the amp as it had a 400 ohm cathode resistor that made all of the power tube choices redplate after about 2 minutes. I used a 750 ohm cathode bias resistor stepping down from an 820 ohm i had tried first. It is spot on the bias now with 455 VDC plate voltage and a solid 42 VDC cathode voltage. Weber says 23 watts with those specs. Could be happier. One nice sounding amplifier. The amp lacked in Bass pretty badly but that was mainly having the wrong bias and not any circuit board mods i believe.
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WOOW--HOHO- What a Mag!!!!
Yeah it weighs more than the whole amp it self! :l2:
Brad :icon_biggrin: