How can I turn a 2 channel Twin amp into a 1 channel Twin ?

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asmara
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Post by asmara » Fri May 15, 2009 7:35 am

lysander wrote:Show me a $400 Princeton and I'll show you a solid state amp.
.
Around these here parts a typical nice Princeton is 1000-1200.

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mikeyc
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Post by mikeyc » Fri May 15, 2009 7:36 am

RefD wrote:this is why i record with small amps and gig with large ones.

Page and Townshend did the same, as did/do many others.

+1, except I kind of like gigging with small amps too.

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Post by Professor T » Fri May 15, 2009 7:41 am

Dude - I think that between this post and your other one - you just don't like the Twin. It's OK. I had a Deluxe Reverb and I hated it. But I kept it for a long time because so many people told me it was a great amp. Sell your twin and buy something else. I'd say from your recent posts that you want a low wattage head with a separate cabinet. I bought a Blackheart combo and it's a ton of fun.

If you have the option / cash flow, it's good to have amps in different power ranges. I've got the blackheart for really small places (5W), a blackface bassman (a quiet 50W) for bars with a sound system, and a Traynor (90W) for bars with no soundguy or outdoor shows.

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Post by dumbangel » Fri May 15, 2009 8:09 am

Professor T wrote: I had a Deluxe Reverb and I hated it.
Just curious, what did you hate about it? Was it an old one with an aged speaker?

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Post by ashcat_lt » Fri May 15, 2009 1:46 pm

asmara wrote:From my experience input 1 and 2 are equivalent in actual output volume.
Both are DEAFENINGLY loud... in a beautiful way.
Your quote of my quote failed there somewhere along the line.

My point was that the power section of these amps are always wide open. If there's a "Low Gain" input, it usually just pads down the input in a passive manner before reaching the first gain stage. This is the same thing as turning down the volume on your guitar, or the last pedal in your chain.

In a non-Master Volume amp, the Volume controls the gain of the preamp circuit. If you're just turning this up to compensate for a lower input volume, you're not really driving the power tubes any harder are you? The only way to do that is to turn up the Volume (preamp gain) even further. Even in a Master Volume amp, I think this just attenuates the output of the preamp stage, before it reaches the power section. That would allow you to get more preamp distortion with less overall output volume. You're still not hitting the power tubes any harder.


I'd also like to mention that (as has been noted above) halving the output power doesn't come anywhere close to half the SPL level. You need to drop down somewhere around a tenth to get there.

You could use a toaster or a fan to burn or blow off the excess power coming out of the amp before it gets to the speaker. This allows (or even encourages) one to push the power tubes a lot harder. This will get the power tube crunch we think we're looking for. Problem here is that you'll be running your power tubes close to their operational limits, somewhat reducing their lifespan.

Better might be to mod the amp to allow reduction of the heater voltage on the power tubes.

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Post by sound for sandwiches » Fri May 15, 2009 1:58 pm

ashcat_lt wrote: Better might be to mod the amp to allow reduction of the heater voltage on the power tubes.
Don't you mean plate voltage? The heater needs to be at 6.3v for a typical guitar amp tube regardless of the operating point of the tube.

some commercial amps have half-power switches that drop the plate voltage. My music man 130HD did that.

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Re: How can I turn a 2 channel Twin amp into a 1 channel Twi

Post by tdbajus » Fri May 15, 2009 3:08 pm

dumbangel wrote:I love the tone of my Twin Reverb Reissue, but it's unnecessary loud for recording instrument after instrument like I do at home.

I heard one could easily turn this amp into a mono channel amp by removing a few valves and disconnecting 1 of the 2 speakers. Does anyone have more information about this?

Also I never use the reverb/vibrato channels, can I remove any valve that is unnecessary as a result ? Is it bad for the amplifier ?
please forgive me if I am stating the obvious here.

Your Twin is already mono- both speakers are hooked up to the same power amp. Both preamps run into the same power amp. I think you probably already knew this...

If you are talking about making your amp half power, when you pull out two of the power tubes (it has to be the two inside tubes, or the two outside tubes, but never the right tubes or the left tubes) it changes the impedence your amp is looking for.

I'm not sure if disconnecting one of the speakers will make it better or worse...


You can also have your local amp tech put in a pentode/triode switch that shuts down half of each of the 4 power tubes, and drops it down to about half the output. It's pretty cheap.
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Post by ctmsound » Fri May 15, 2009 7:49 pm

Half the power tubes is not half the volume. You'll notice a difference tonally, but it will be just as loud. That and what everyone else said in concerns to running the amp harder and the impedance change.

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Post by ashcat_lt » Fri May 15, 2009 7:49 pm

sound for sandwiches wrote:Don't you mean plate voltage? The heater needs to be at 6.3v for a typical guitar amp tube regardless of the operating point of the tube.
You know, that's what I thought it was, but somebody - whose knowledge of these things I respect better than my own - recently "corrected" me...

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Post by Professor T » Fri May 15, 2009 11:00 pm

dumbangel wrote:
Professor T wrote: I had a Deluxe Reverb and I hated it.
Just curious, what did you hate about it? Was it an old one with an aged speaker?
It was a '76 corksniffer - JJ tubes and a celestion gold. I just didn't like the way it was voiced. It was too bright and harsh with my 6120 - and it was too loud to crank, but not loud enough to be clean. I just didn't get that one. I like dark amps.

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