power reduction tubes?

[Road King]

Bought an amp tonight. The seller threw in a pair of power tubes he had. They are Groove Tubes Substi-tubes. They are supposed to reduce the power from 50 watts to about 22 watts. From class A/B to class A.
Has anyone tried anything like this before? Results? Any problems? I know nothing about this kind of thing and I am a little reluctant to just install w/o some advice. The amp is a Mesa and I will be calling them tomorrow to get their take.

Thanks guys,

Brad

[tom]

sounds like the thd yellow jackets. what tube is in them?

[crash]

I have Yellow Jackets and EL84s in my Fender DeVille. Gives it the Class A Vox-type sparkle, which is a nice change from the punchy Fender clean sound. I like it and use it a lot that way.

I've had no problems at all. Some of the YJ converters require a grounding lead, some don't. The 6L6-to-EL84 converters don't, so I can switch back and forth between the converters and 6L6s all I want with no other amp mods.

I do recommend using an oven mitt if you do it frequently...

I think I've heard that Mesa recommends again tube converters, but I don't know why. Should be interesting to see what they say.

[Road King]

The tubes are el84, specificallyGroove Tubes Gold Series Substi-Tubes, GTEL84S model 928-PR. They have large adapters that the el84's plug into that say power reducers. Marcus at Mesa called a few minutes ago and said that he did not see any problem in using them if they were anything like the yellowjackets. But he also said I should check with the manufacturer to be completely certain.

Thanks

Brad

[crash]

A pair of Substi-tubes converters (with the EL-84s) is over $100 new, so that's a nice little kicker with the amp.

At this point, you can figure out what tubes the amp uses normally, stick in a set, and then switch back and forth and see which you like better.

[Road King]

No kidding on the kicker! I was a little shocked when I saw the direct price on the GT site. Talked to the customer service guy at GT and he relays that they are fine in the Mesa and that I should get a real AC 30 type vibe from them. What seemed a little strange was he said not to change the bias switch from 6L6 (the factory installs) to the EL84 setting. Haven't had a chance to try them out yet, but I'm looking forward to it. Now it's time to go delay shopping. Analog or digital? The fun never ends. Only the bottom of the wallet keeps showing up.

Thanks for your help guys,

Brad

[kurt1981]

Hey Brad, glad you found an amp, I figured since I didn't hear from you on the fandango. Just Fyi, I'm selling a nearly mint boss gigadelay, in box for $145, if interested, it's a great delay, does all the bells and whistles, but it's very easy to use. Let me know if interested, and which mesa did you end up with?
Kurt

[Road King]

My bad dude, I read a post that said you were considering keeping it and figured that was the reason you didn't send the pics. Then the guy whose amp I had been using needed it for another gig. Two services this week and a gig on Saturday and suddenly I felt the urgency level rise beyond all capacity for restraint. (I could have borrowed the bassists solid state Marshall but,......dang). Anyway, it is the Rectoverb combo 112. Not perfect but has some very cool tones nontheless. Actually very suprised at the quality of the clean tones. Very tweaky in the EQ though, so I will have to get used to that. Definitly interested in the delay. I will try to get to GC tomorrow and plug one in. Does the price include shipping?

Thanks

Brad

[kurt1981]

Yep, shipped to your door. Nice choice, I have a lonestar that I've decided to keep. I did send the pics, but I've been having some email troubles lately, bad servor I think. Let me know, the delay's very cool.
Kurt

[crash]

1) You don't have to flip the bias switch on the amp because as far as the amp knows, you're still using 6L6s. The Substi-Tube (or yellow jacket) does all the work. No re-biasing; instant class-A EL84 mojo.

2) Get the Giga delay.

[Road King]

Well with Kurt and Crash in the Giga Delay corner how can I go wrong? Plus I saw one on a picture of Tom's pedal board. So in the mouth of two or three witness call it sold. PM for payment instructions.

Thanks

Brad

[Road King]

OK, put in the power reducing el84s. Very cool vibe. Crash was right on with the Voxy Brit tone. I really like the clean tones better than the overdriven. This amp has a ridiculous amount of gain and I can get some excellent crunch tones to go w/ the cleans, but oddly enough I am having a problem finding a wet lead tone w/o getting too fuzzy. I think the delay will remedy the situation by fattening up the crunch and giving it a wet feel. Anyone else have any tricks they want to share?

Brad

[Rob C.]

The Rectoverb is basically an old 2 channel Dual Rec preamp circuit coupled with reverb and a 50 watt output section. Try replacing the 1st pre-amp tube (under the sheild) with a lower output tube. If it's currently a Mesa 12AX7 or SPAX7 try a Groove Tube 12AX7R. More tone, a bit bigger sounding and noticably less of the "fuzzy" gain. It's because they cascade so many gain stages in that pre-amp and it creates the fuzzy sound regardless of where the gain is set at.

Hope this helps, Rob

[Mister T]

I used to own a Rectoverb. I and MANY other Rec owners found that the new reissue Tung Sol 12AX7 tubes in the V1 position made the amp sound far better

[crash]

I put better glass in my Deville and it helped - that is worth trying.

I also put in better speakers (a Weber 12F150 and a Cannabis Rex), and the tube converters. I love it, but it now no longer sounds ANYTHING like a Fender DeVille. But I digress...

For the DD-20, getting a Boss FS-5U to use as an external 'tap tempo' switch is a huge benefit. MUCH easier to use than the built-in tap tempo feature.