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#1 2014-02-26 17:12:47

ROBO
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From: na
Registered: 2010-01-26
Posts: 134
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Questions about removing power tubes to slave preamp

So in my other thread about my V4 blowing one of its KT88's I mentioned pulling 2 of the tubes after the one died so I could run in a Half-Power configuartion.

But then I got to thinking once I saw my V4 sitting on top of my SVT.

I like the tone I get out of the V4 better than the SVT honestly, even with a Sans Amp pedel the V4 on its own still sounds better than the SVT.

So what I want to do is slave out of my V4's preamp and run it into the slave input on the SVT's poweramp.

The only problem with this is that the V4 would be running without any speaker load which is a big NO-NO.

So what I am wondering is if I could just pull all the power tubes out of the V4 to completely disable its power section.

Would this work just pulling the tubes OR do I still need to lift the main voltage feed from the output transformers center tap to keep it safe?


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#2 2014-02-28 10:19:43

hangman
Banned
From: Seattle Washington
Registered: 2006-09-04
Posts: 1848

Re: Questions about removing power tubes to slave preamp

You could alternately remove the 12au7 phase inverter.  Or just disconnect the preamp from the power amp by lifting a resistor.   I would leave the power tubes in.  If you remove them the power supply voltages can go quite high.

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#3 2014-03-09 02:32:23

ROBO
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From: na
Registered: 2010-01-26
Posts: 134
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Re: Questions about removing power tubes to slave preamp

Good point Steve. After thinking about it a little more my plan of slaving the V4 into the SVT wouldn't really get me where I want anyway.

Part of the reason I like the sound of the V4 is the master volume I added and it is Post phase inverter. So If I slaved out of the V4 its master volume would be of no use since it is in the power amp section.


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#4 2014-03-10 17:14:23

hangman
Banned
From: Seattle Washington
Registered: 2006-09-04
Posts: 1848

Re: Questions about removing power tubes to slave preamp

oh yeah,  that does kinda defeat the purpose.

although,  adding a volume control between the v4 and the SVT wouldn't be too difficult.

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#5 2014-06-03 21:25:44

ROBO
V.I.P.
From: na
Registered: 2010-01-26
Posts: 134
Website

Re: Questions about removing power tubes to slave preamp

Been thinking more about this lately Steve. There really isnt anyway for me to take the V4's signal after the master volume, because it is after the phase inverter and it is already split in two.

I could go out of the V4's ext jack and slave into the SVT's EXT jack. That would give me the V4's preamp, linked to the SVT's power section. But I would still need a way to over drive the V4's preamp to get the sound I'm after, I like that overdriven master volume sound I get out of my V4.

I Ampeg master volume boxes that hook into the EXT jack sound like crap. They work but they only give you a clean tone, the way they tap into the circuit through the EXT jack does not allow you to overdrive the preamp.

How would I go about adding a volume control between the V4 and SVT?
I could remove one ofthe EXT jacks on the V4 and place the knob in its hole. But how should I wire it in and what size Pot do you think would be a good starting point?
1M? 500k?
I'm going to try this because its interesting and I'm curios but I am doubting it will have the same volume/tone characteristics as the post phase inverter master volume


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