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mrhat

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Hey guys, i just got a used rectoverb combo off ebay, and when i got it in today,its kinda noisy and i think one of the powertubes might be bad, it makes a kinda buzzing noise until i touch it with my fingernail, then it stops. is this for sure a powertube problem? this is my first tube amp, so i am a little in the dark about that stuff. also, if i need to replace the powertube, since the rectoverb has an autobias, can i use most any 6l6 matched pair in it? sorry about all the questions
 
Go here: www.eurotubes.com

Read about tubes in general, email Bob regarding your needs, and then make an informed decision.
 
I'd also check out www.thetubestore.com. They offer comparable prices to www.eurotubes.com, have a far better selection, and don't read like a commercial for JJ tubes. (Don't get me wrong, I've read that JJ tubes are great and will probably try them at some point; I just like choice.) Furthermore, they guarantee their tubes for 90 days. I actually had one of two Svetlana 6L6GC's go bad during the 90 days and they replaced BOTH of the power tubes with a different brand no less (Electro-Harmonix, for the curious) with no hassle whatsoever. I was very impressed. Just be sure to tell them what type of amp you have and they'll send you a proper match.

By the way, I really like the EH pre and power tubes in my F-50 combo. They were a very noticeable (if not vast) improvement over the stock Mesa tubes, though I found no appreciable difference between the EH power tubes and the Svetlana's I'd previously had in it.
 
Bob at Eurotubes is a pleasure to work with. I've also worked with Doug at http://www.dougstubes.com and had the same great customer service.

FWIW, I didn't care for the JJ ECC83 preamp tubes in the V1 slot of my amp...it was too dark for my taste.
 
mrhat said:
Hey guys, i just got a used rectoverb combo off ebay, and when i got it in today,its kinda noisy and i think one of the powertubes might be bad, it makes a kinda buzzing noise until i touch it with my fingernail, then it stops. is this for sure a powertube problem? this is my first tube amp, so i am a little in the dark about that stuff. also, if i need to replace the powertube, since the rectoverb has an autobias, can i use most any 6l6 matched pair in it? sorry about all the questions

If the tubes are making buzzy noises, that's normal. It's the effect of the heater current being applied to the power tubes.

If you're experiencing a buzzing noise coming from the speakers and it subsides when you hit the strings on your guitar, you've got a grounding problem that needs to be worked out.

Lastly, the Rectos aren't autobiased. They're fixed biased amps in which the bias (grid voltage) is set with a non-adjustable resistor. Amps with bias pots are fixed bias amplifiers as well, but the bias pot is a variable resistor.

You'll learn more as you read more.

As far as current production tubes in a Recto go, I like EH and 9th Generation Chinese 12ax7's.

As far as power tubes are concerned... SED 6L6GC's, SED EL34's, EH EL34's, JJ 6L6GC's (these typically run too cold), Ruby EL34B-STR's (these are awesome) and JJ E34L's or JJ EL34's. I'm sure there are others that I've tried that I'm not thinking of at the moment.

As far as The Tube Store is concerned, I don't like them. Sure, they have a nice assortment of tubes, but they don't test them as well as some other vendors do.

Here is who I use:

Lord Valve - 303-778-1156
Doug's Tube - www.dougstubes.com
KCA NOS Tubes - www.kcanostubes.com

Dale
 
Dale B. said:
Ruby EL34B-STR's (these are awesome)
Dale

Interesting my Triple rec (used) came with these and this is the first mention of them I have seen.

Do you prefer these over 6l6's ? I am not too sure I like the Ruby's in there.


a different question is that in the manual it mentions jotting down the location of the pre amp and power amp tubes when your taking them all out to replace I never did this when I changed my pre amp tubes the other night ( meaning the power tubes I swapped all of the pre amp tubes) what is the reason for this and how much of a difference would this make ? how do you determine in the first place where they go ?

I semi understand the pre amp tubes method but have never heard of it for the power tubes untill reading the manual now I am worried I did it wrong when I first fire up the amp there is a hiss very strong but if I put it back into standby and then fire it up again it goes away this is new after I changed the tubes any idea why this might be ever heard of this before ?
 
mrdylan said:
a different question is that in the manual it mentions jotting down the location of the pre amp and power amp tubes when your taking them all out to replace I never did this when I changed my pre amp tubes the other night ( meaning the power tubes I swapped all of the pre amp tubes) what is the reason for this and how much of a difference would this make ? how do you determine in the first place where they go ?

With the preamp tubes, you would want the least noisy one in the V1 spot, as noise is amplified again and again by the following tubes. A noisy tube wouldnt be as much a problem in V3. Also if you think you might have a bad one, its easier to figure out which one it is if you start switching them around.

As for the power tubes, if you got them as a matched sextet, I dont think it would really matter where they go. If you got 3 matched pairs, you should probably keep them in pairs. 1-6, 2-5, 3-4. That way each tube is running with its match.
 
**** the power tube are all over the place now except for the first 2 which I didn't have to remove to change the pre amp tubes and to be honest I've not a clue whether the guy before me got matched sets or what not.

as for the pre amp tubes how do you find out which is the noisiest ? should I be able hear this or is there a certain way of doing it ?

I have had tube amps before but never changed the tubes and there wasn't nowhere near as many as what are in my Triple.

Thanks for the help
 
mrdylan said:
**** the power tube are all over the place now except for the first 2 which I didn't have to remove to change the pre amp tubes and to be honest I've not a clue whether the guy before me got matched sets or what not.

as for the pre amp tubes how do you find out which is the noisiest ? should I be able hear this or is there a certain way of doing it ?

I have had tube amps before but never changed the tubes and there wasn't nowhere near as many as what are in my Triple.

Thanks for the help

If you have Ruby tubes in your Triple Recto, they should have a little label stuck on the base of the tube that tells you two things: (1) The Cathode Current (bias) they were drawing at whatever plate voltage they tested them at (this is usually 400 volts). (2) The transconductance. The transconductance will be a number in and around the 4000 area. It will have 4 numbers.

Now, with that said, you will want to look back and see if they are paired up correctly.

Let's say you have pairs that have been labeled like this:

29 - 4500 < Pair 1
28 - 4350 < Pair 2
30 - 4750 < Pair 3

You will want to place the pairs in the appropriate tube sockets where they will be working together with one another.

You can put the tubes from Pair 1 in the Two Outer sockets...Socket 1 & 6.
You can put the tubes from Pair 2 in Sockets 2 & 5.
You can put the tubes from Pair 3 in Sockets 3 & 4...The two innermost sockets.

That's just an example. You can check back and see what they look like right now, if you haven't already done this.
 
mrdylan said:
Dale B. said:
Ruby EL34B-STR's (these are awesome)
Dale

Interesting my Triple rec (used) came with these and this is the first mention of them I have seen.

Do you prefer these over 6l6's ? I am not too sure I like the Ruby's in there.


a different question is that in the manual it mentions jotting down the location of the pre amp and power amp tubes when your taking them all out to replace I never did this when I changed my pre amp tubes the other night ( meaning the power tubes I swapped all of the pre amp tubes) what is the reason for this and how much of a difference would this make ? how do you determine in the first place where they go ?

I semi understand the pre amp tubes method but have never heard of it for the power tubes untill reading the manual now I am worried I did it wrong when I first fire up the amp there is a hiss very strong but if I put it back into standby and then fire it up again it goes away this is new after I changed the tubes any idea why this might be ever heard of this before ?

I usually swap back and forth between the Ruby EL34B-STR's and some Philips 7581A's. The Ruby EL34B-STR is the fattest sounding current production EL34 type tube that I've tried in the Rectos. They tend to have a ballooning effect in the power section where they exagerate everything and fatten it all up. I find that to be fairly amazing that they're able to do this at such low bias settings like the Rectos have.

Let's look at what I get from my Triple in the Bold/Silicon Diode mode with a sextet of Mesa spec'd EL34's and then I'll show you the Ruby's.

With some Mesa spec STR-442's I get a plate voltage right at about 450 and the bias is right at 25 mA. The plate dissipation at idle current is only 45%. That's running pretty cold there and the tone is compressed and washed out.

Now, let's take a look at the Ruby's that I have in this amplifier. The Plate Voltage is still right in the 445 to 450 area and the bias is 25 mA. The plate dissipation at idle is pretty much the same, but the tone is fatter than the STR-442's. They're still running cold, but they're able to add a fattness to the power section. Also, they tend to smooth things out and make the power section rounder.

It's mainly an issue that comes down to preference. That's just what I think and what I've found out by tinkering around with the amplifier. The figures that I've stated above are not universal from Recto to Recto either. The plate voltage can vary depending on what is being supplied to the amplifier at the wall socket. The Cathode Current (bias) pretty much stays in the same area when you're running Mesa Spec tubes and these Rubys that I have are within Mesa's specs. It just goes to show you that they operate a lot differently than a lot of the other current production tubes.

Do I like the Ruby's better than 6L6GC's? I don't know. I've come to the point to where I can find a lot of different attributes with a lot of different tubes. It all depends on what particular tones I'm wanting to come out of the amplifier. The 7581A, that I slightly mentioned above, is a super 6L6GC. It has more power and is cleaner sounding, yet it still sounds like a 6L6GC...It's just cleaner and clearer. I like that vibe in these amplifiers a lot. Randall Smith used Sylvania tubes almost exclusively in the older Mark Series amplifiers in the 70's and 80's. Philips bought out Sylvania. So, I'm not doing anything wrong by running these tubes in this amplifier.

Dale
 

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