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Old 3rd February 2006, 12:04 AM   #1
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Default Can you run a Fender Twin Reverb with only two 6L6's?

I have a Fender Twin Reverb '65 reissue and I use it mainly in a small room in my apartment (yes, I didn't know what I was getting myself into when I bought this awesome beast). It just doesn't get a good, fat, full tone until the volume is in the 2 - 3 - 4 range, and by then it's *way* louder then I want it. I'm looking for a way to reduce the power that this amp puts out as it is way more than I need.

OPTION 1)

If searched about pulling two of the 4 main 6L6 power tubes to cut the wattage in half. My goal is to get a good, full, warm tone at a reasonable volume (I'm not trying to crank it to get distortion out of it - that's what my TS9 and RAT are for).

I read that you can pull either the two outside tubes...
UUUU => *UU*

...or the two inside tubes to achieve this.
UUUU => U**U

I ran it *UU* last night and it worked like I'd hoped. Now I can get that nice tone with the volume on 3 and not blow out the up and downstairs neighbors. However, will this damage the amp? I read that running only two 6L6's the cuts the Ohms from 8 to 4 and that you need to then switch something else (I think that might have been referring to head units that plug into separate cabinets), but there's no "Ohm switch" on this amp. I have two 8 Ohm Celestion Vintage 30's for speakers - will this 2 tube setup be okay?

OPTION 2)

I've heard about tube converters where they plug into the 6L6 sockets and then you plug in 6V6's or EL34 (not sure if that's right). Anyone try these - with what results? There is stuff on the web about Jester Enterprises Black Jack tube converters but I can't find their web page.

Thanks in advance!
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Old 3rd February 2006, 12:37 AM   #2
gl is offline gl  United States
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Yes you can do this but I don't remember which two tubes. Two of the tubes have 1500 ohm series grid resistors to prevent oscillation with the parallel tubes. The ones without are the ones I'd remove. You shouldn't hurt anything doing this - at least I've never seen this damage an amp. People used to do this if a tube went bad while performing. They would pull out the tube on the other side, turn up the volume and keep playing. Invariably it would be months before they bought a replacement tube. A friend with one of the Fender bass amps with six output tubes would go from six to four to two before he went out and bought new tubes.

As an aside I used to install two extra 6L6's in black face Bandmaster amps for a fee back in the sixties. It was easy - the two amps are built on the same chassis and the holes for the extra tubes were already there. It would sound great till the output transformer went. Then you'ld have to put in a bigger one - a hammond 1664 IIRC, which is no longer made.

Enjoy.

Graeme
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Old 3rd February 2006, 03:10 AM   #3
poobah is offline poobah  United States
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You can also "power soak" your amp... It's means putting some resistance (L-PAD) in your speaker's wiring to burn off some power.

I could tell you how if I knew the speaker's ohms and connections and how many dB you want to kill

It's supposed to be a good method because you keep your tube/tranny distortion and your power supply sag intact... you lose breakup on the cones but... oh well.

You can buy these gizmos off the shelf too... google power soak and L-pad.

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Old 3rd February 2006, 03:47 AM   #4
Trout is offline Trout  United States
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Quote:
Originally posted by poobah
You can also "power soak" your amp... It's means putting some resistance (L-PAD) in your speaker's wiring to burn off some power.

I could tell you how if I knew the speaker's ohms and connections and how many dB you want to kill

It's supposed to be a good method because you keep your tube/tranny distortion and your power supply sag intact... you lose breakup on the cones but... oh well.

You can buy these gizmos off the shelf too... google power soak and L-pad.

Lotta Amp manufactures ( Not Vintage Fender) void warranty if you use items like power soak, Something about inductance Flyback messin up the OPT?
Ever hear that before?

Heres a Quote:

Quote:
What is normal intended usage:

Cranking up (or down) and playing your heart out with an electric guitar! This includes using reactive type attenuators, such as the Dr. Z Airbrake, or Marshall Powerbrake. Of the non-reactive attenuators, only the 8 ohm THD Hotplate is covered.

What is misuse:

Use in inclement conditions, improper voltages, and resistive type power attenuators, that create huge flyback voltages (like the "Power Soak.").

Use of improper tubes, or socket adapter devices, intended to run incorrect tubes in the amplifier.

Modification of the amplifier circuitry, other than changing of tubes and speakers.

Impedance mismatching.
Gene
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Old 3rd February 2006, 04:08 AM   #5
poobah is offline poobah  United States
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Hey Gene,

I guess in recent years they starteed adding inductance to these things to make the sound more "right" and that could mess things up. I took my own advice and googled... there's lotsa gizmo's out there. Pure resistence shouldn't hurt anything though.

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Old 3rd February 2006, 11:34 AM   #6
Trout is offline Trout  United States
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Quote:
Originally posted by poobah
Hey Gene,

I guess in recent years they starteed adding inductance to these things to make the sound more "right" and that could mess things up. I took my own advice and googled... there's lotsa gizmo's out there. Pure resistence shouldn't hurt anything though.

I often wonder when I read the warranty FAQ's if its more to limit endorsements to the competition Vs Reality. I only came across the above warranty quotes because A guy is dropping off his boutique Marshall clone today for a warranty repair. In gathering the info from the vendors site, I read his lifetime warranty info on his FAQ page and saw that power soak stuff.
I imagine his customer must be a fairly laid back kind of guy seeing as his $1900.00 week old 18W amp has issues rendering it not playable.( 2 of the pre-amp tubes have filament power dropping out).

He will be stuck using his Hiwatt custom 50 for the weekend, Poor Guy, " NOT"
Gene
EDIT:
Hey, In the original post, he talked about Blackjack Tube converters, I wonder if he meant Yellow Jackets

Though 4 of those would be alot of $$$$ and he would still end up with over 25W of thunder!
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