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Author: Subject: Twin Reverb Tube Question

A Peach Supreme





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  posted on 5/18/2009 at 12:49 PM
I have been thinking about removing several of the tubes from my 65 Reissue Twin Reverb to lower the wattage. Question is, which do I need to remove? I'm hoping after I remove the tubes it will lower the wattage to around 40 or so. Here is the tube layout.

4 X 12AX7,
2 X 12AT7,
4 X 6L6,

Any help from you guys would be appreciated.

 

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Peach Extraordinaire



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  posted on 5/18/2009 at 01:07 PM
quote:
I have been thinking about removing several of the tubes from my 65 Reissue Twin Reverb to lower the wattage. Question is, which do I need to remove? I'm hoping after I remove the tubes it will lower the wattage to around 40 or so. Here is the tube layout.

4 X 12AX7,
2 X 12AT7,
4 X 6L6,

Any help from you guys would be appreciated.


I'd go to the fender forum and ask this question but the 6L6's are the power tubes so removing two of them will cut the power but I don't know if it's safe to run your twin that way. You will find that answer over there under the amplifier forum

http://www.thefenderforum.com/forum/forumdisplay.php?f=9

The 12ax7's and 12at7's are preamp reverb and tremolo tubes

[Edited on 5/18/2009 by goldtop]

 

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  posted on 5/18/2009 at 01:17 PM
Thanks for the link.

 

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  posted on 5/18/2009 at 07:42 PM
You can pull two of your 6L6's, the inside or outside pair.

BUT,

1. you will have to re-bias the amp.
2. you will have to change the impedance of you speakers.
3. you will probably be disappointed with the results.

This method does not actually cut your wattage by half, more like 30%. And even if it was by half, that would only be a 3db difference in volume- not much.

In reality, you could achieve the same results by increasing you speaker load. Try rewiring the two 8 ohm speakers to 16 (series) The extra load reflected back to your output xfmr will give a perceived decrease in wattage.

 

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  posted on 5/19/2009 at 10:50 AM
quote:
You can pull two of your 6L6's, the inside or outside pair.

BUT,

1. you will have to re-bias the amp.
2. you will have to change the impedance of you speakers.
3. you will probably be disappointed with the results.

This method does not actually cut your wattage by half, more like 30%. And even if it was by half, that would only be a 3db difference in volume- not much.

In reality, you could achieve the same results by increasing you speaker load. Try rewiring the two 8 ohm speakers to 16 (series) The extra load reflected back to your output xfmr will give a perceived decrease in wattage.


That's what I was afraid of. Thanks for the tips. I think I will leave it the way it is.

 

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  posted on 5/19/2009 at 03:14 PM
quote:
You can pull two of your 6L6's, the inside or outside pair.

BUT,

1. you will have to re-bias the amp.
2. you will have to change the impedance of your speakers.
3. you will probably be disappointed with the results.



hey y'all

for what it's worth, i've removed 2 of 4 on a Randall (with not good results) ... not worth it, IMO.

ampsnob, i'm curious, why would (changing) the speaker impedance be relevant? Thanks.

Peace.

 

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  posted on 5/19/2009 at 05:46 PM
It has to to with the load reflected back to the output xfmr and power tubes. Without getting over the top technical, loading an 8 ohm tap with a 16 ohm load changes the impedance that the output section sees, thus lowering the power.


 

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  posted on 5/20/2009 at 07:31 AM
Have you considered an attenuater?
That sounds like just the ticket.

 

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  posted on 5/20/2009 at 01:39 PM
quote:
I went thru the same situation with my Twin Reverb recently. Gotta crank it to get those tubes workin' for ya, but it's too damn loud. Right?

First, like you, I explored the possibility of pulling power tubes, but came to the same conclusion you have -- it's not worth it.

I then spent a few hundred bucks on the THD Hotplate power attenuator, but I quickly found out that you can't buy but 2 maybe 3 notches on the Twin's volume before the attenuator starts eating tone. Barely beneficial, and adds more pain to setup/teardown of your gear. I'd prefer to just plug in and go.

Finally I came to the realization that the Twin is just not the right amp for me. Of course I still have it, but I went out and bought a Peavey Classic 50 4/10 to be my "big" amp.

I think you might find that replacing the amp is probably your best bet overall...


Twins are just the loudest cleanest amps there are......If you want sparkling cleans it the amp to go with if you want crunch at a volume that won't make you sterile it's not the amp for you....They don't even break up at high volumes they just get louder......30 to 40 watts is going to be enough for most players to achive good clean overhead but will still breakup at a more reasonable volume. I have a 40 watt 67 BF Pro reverb that I bought about 25 years ago......I used a twin for a while but I had the same problem that everyone else is talking about......just way too loud and heavy. The pro gives me everything the twin does and it's at times too loud and it's only 1/2 the wattage. But I need 40 watts to get the clean headroom I require. I tried a 20 watt amp but they just breakup too soon especially with a LP or 335

 

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  posted on 5/20/2009 at 01:51 PM
Somebody else noticed you gotta crank a twin up to 10 or 11 to get some tone without the aid of any effects ? I'm shocked.

 

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  posted on 5/20/2009 at 02:10 PM
There use to be an effect box ... called a power soak or something like that. Basically, it "absorbed" some of the amp's power. I've got a early 70's Ampeg VT-22. If I turn it past 2, all the pictures, mirrors and wall hangings in the house shake off the walls. A guy loaned me one of these things years ago and I was able to get "tone" (distortion?) at low volume levels. This device would get real hot! (energy dissapates as heat, right?). Seems like the guitar player from Boston was involved in the design.

 

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  posted on 5/20/2009 at 02:34 PM
change your output transformer. chances are the wattage is too high. i have a 1973 fender quad reverb, had the exact same issue. wasnt getting the tone i wanted. found out that it was a 100watt amp, called my tech he recomended changing the output transformer to a 50watt. then he removed two of the 6L6 tubes. after all that he coverted the silverface circuitry to blackface scheme. also if you remove the normal channel input tube it will increase gain in your vib/trem channel.
cost me a little bit but well worth it!
my amp now screams without making my ears bleed
with a little work those twin & quad reverbs can sound amazing.

 

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  posted on 5/20/2009 at 05:28 PM
I read an interview with Gary Duncan who shared lead/rhythm with John Cippolina in Quicksilver Messenger Service. Cippolina had this huge, strange rig with amplifiers and horns (I may have read that it's in the Smithsonian now) that was so brutally loud that Duncan was playing through EIGHT (8, yes, e-i-g-h-t) Twin Reverbs to compete!

 

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  posted on 5/20/2009 at 09:00 PM
quote:
I read an interview with Gary Duncan who shared lead/rhythm with John Cippolina in Quicksilver Messenger Service. Cippolina had this huge, strange rig with amplifiers and horns (I may have read that it's in the Smithsonian now) that was so brutally loud that Duncan was playing through EIGHT (8, yes, e-i-g-h-t) Twin Reverbs to compete!


Here's John Cippolina's rig http://www.johncipollina.com/rockAmpStack.htm

 

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  posted on 5/21/2009 at 12:06 AM
quote:
change your output transformer. chances are the wattage is too high. i have a 1973 fender quad reverb, had the exact same issue. wasnt getting the tone i wanted. found out that it was a 100watt amp, called my tech he recomended changing the output transformer to a 50watt. then he removed two of the 6L6 tubes. after all that he coverted the silverface circuitry to blackface scheme. also if you remove the normal channel input tube it will increase gain in your vib/trem channel.
cost me a little bit but well worth it!
my amp now screams without making my ears bleed
with a little work those twin & quad reverbs can sound amazing.


I'm a Quad fan...but man them suckers are heavy. Gave it to my son.

 

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  posted on 5/21/2009 at 03:57 AM
The other alternative is to get the low wattage Twin. When they first came out, I think they were 40 watts, newer ones being 100W

 

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  posted on 5/21/2009 at 07:05 AM
quote:
I think you might find that replacing the amp is probably your best bet overall...


This is the best advice so far. Power soaks/attenuators can shorten power tube life, and expensive mods may not end up sounding how you want. If your amp doesn't do what you want it to, get a different one.

If you want your amp to break up/distort the Twin Reverb is not the amp of choice.

 

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  posted on 5/21/2009 at 08:13 PM
I would love to have one of the Fender 57 Twin-Amps but the price on this amp has gone through the roof.

 

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  posted on 5/21/2009 at 09:11 PM
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I would love to have one of the Fender 57 Twin-Amps but the price on this amp has gone through the roof.


I have one and it's great....I got it used from Dave's in Wisconsin......They can be had for about 1/2 the price used but that's still quite a bit. I traded a LP for it. They break up nice at about 4 1/2 and still have nice cleans when you turn your guitar volume down. Put it between 5 and 7 and you don't need a Distortion pedal and again they clean up real nice with the guitar volume down.

 

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  posted on 5/22/2009 at 06:03 AM
Wow, they sure did go up. I haven't checked in a while. I got mine off ebay and I love it. Keep an eye out for used and good luck.

[Edited on 5/22/2009 by michaelsio]

 

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  posted on 5/23/2009 at 07:17 AM
For a replacement, look at a Goodsell.
His Super 17 has reverb, tremolo, single or double 12" speakers and is variable from either 5 W or 17W.
He also uses Hammond organ amps to power his units IIRC.
www.emeraldcityguitars.com has at least one, possibly two now.

 

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  posted on 5/24/2009 at 06:27 PM
quote:
quote:
change your output transformer. chances are the wattage is too high. i have a 1973 fender quad reverb, had the exact same issue. wasnt getting the tone i wanted. found out that it was a 100watt amp, called my tech he recomended changing the output transformer to a 50watt. then he removed two of the 6L6 tubes. after all that he coverted the silverface circuitry to blackface scheme. also if you remove the normal channel input tube it will increase gain in your vib/trem channel.
cost me a little bit but well worth it!
my amp now screams without making my ears bleed
with a little work those twin & quad reverbs can sound amazing.

Can you do this with the more current circuit board type models? Mine is a '65 Reissue.


im guessing that they might have already duplicated the blackface circuitry for your 65 reissue. if you have the option to use just your channel volume or if you have no master volume it probably doesnt need to be blackfaced. you definatley will want to change your output transformer and i strongly recomend removing one of the clean channel tubes to increase your gain. once your amps wattage has been lowered you will be able to crank your channel volume, the tubes will saturate and you will have the tone you quest for.
ps.it will still be loud but not nearly as ear peircing as it would be if you left it as a 100watt amp

 

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  posted on 5/24/2009 at 11:38 PM
quote:
There use to be an effect box ... called a power soak or something like that. Basically, it "absorbed" some of the amp's power. I've got a early 70's Ampeg VT-22. If I turn it past 2, all the pictures, mirrors and wall hangings in the house shake off the walls. A guy loaned me one of these things years ago and I was able to get "tone" (distortion?) at low volume levels. This device would get real hot! (energy dissapates as heat, right?). Seems like the guitar player from Boston was involved in the design.


Tom Scholtz from Boston. Power Soak was the device

 

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  posted on 5/29/2009 at 02:27 PM
After considering the 57 Twin, I actually just ordered one of the PRS Dallas 50 Watt heads. From I understand, it's a Twin Reverb on steriods.

 

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