This Super Twin I converted into a head cabinet for bass guitar came with 4 Ruby 6L6GCMSTR which I think are relabelled russian tubes of some kind, and 2 Groove Tubes GT6L6S with power-match code "7" which I think are relabelled JJ tubes.
They were in the wrong sockets, so push was 3 Ruby and pull was 2 Ruby and 2 Groove Tubes.
I want to use this for bass, so power matters much more than breakup mode.
What's my best course of action? Stick with what I have and stick them in the correct sockets so push & pull at least have the same complement? Trade someone the GTs for a pair of Ruby? Look for 4 GTs w/ code "7" and sell the Rubys? Look for old made in the USA tubes?
They were in the wrong sockets, so push was 3 Ruby and pull was 2 Ruby and 2 Groove Tubes.
I want to use this for bass, so power matters much more than breakup mode.
What's my best course of action? Stick with what I have and stick them in the correct sockets so push & pull at least have the same complement? Trade someone the GTs for a pair of Ruby? Look for 4 GTs w/ code "7" and sell the Rubys? Look for old made in the USA tubes?
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I'd buy 6 new ones from here
6L6GC, JJ | Antique Electronic Supply LLC
they will match 6 up for you then you no what you've got, unless you hav access to a tube testor and trying to find 6 second hand that match close could be a big ask.
6L6GC, JJ | Antique Electronic Supply LLC
they will match 6 up for you then you no what you've got, unless you hav access to a tube testor and trying to find 6 second hand that match close could be a big ask.
If vou do not have a chance to test the tubes for wear and matching this is difficult to answer. If they do not *look* too used I personally would give it a try and put equal combinations into each half of the power stage as you suggested, turn the "matching" pot to mid position and go.
I don't know man I heard bad things about the JJ 6l6gc's, What you have could be Chinese or the JJs or some other Russian Variant. You could look into the new Tung-sols I thought those sounded good as well as the SED/Svetlana
Those old RCA black-plate 6L6's have some real Magic going on inside them but you are gonna pay for it 🙂
Its up to you I would just experiment with different ones then you could find what suites you're tastes, I'm just scared of current production tubes, I have had some nightmares or it was just really bad luck lol
Had not too good experience with JJ either. If they withstand the first three months or so they may be as durable as any other brand tube, but I had too many failing within a few days and therefore stopped using them. The ones in the the super twin are not really new as I understand, so why not in this case. Anyway, it depends on how much you are willing to spend.
Yeah lots of the JJs dead out of the brand new boxes etc lol but usually if they make it past that 3 month point they are some keepers lol I have 1 JJ ecc83s that sucker is still going its like 3 or 4 years old I went through like 10 of them over the years some dead right out of the box others would last a few days or a month etc lol. Their 6v6s is kinda a hit and miss though they sound pretty good but they will rattle themselves apart lol
I'm interested in trying something different myself though the JJ eec83s had good gain but I found its kind of hollow/narrow on the low end and harmonics are nothing special, they seem to have less Edge too. I miss some of those old Chinese 12AX7s I had, those were some edgy bastards lol bright but man they could cut buddy lol, just more of a pissed off sound lol
What's wrong with actual measuring vs. guessing?
Scope the amp driven to *just* clipping and check:
1) how much it's actually putting out. Anything above 120W RMS is excellent.
2) symmetry.
If symmetrical clipping within 5% or 10% (which I doubt is happening now , except by sheer chance), fine.
If not, do the musical chairs game:switch right/left a couple until you get a match.
Wit the bias balancing pot set to middle, of course, so you are actually matching thge tubes themselves.
When real close, only then use the pot for final tweaking.
Scope the amp driven to *just* clipping and check:
1) how much it's actually putting out. Anything above 120W RMS is excellent.
2) symmetry.
If symmetrical clipping within 5% or 10% (which I doubt is happening now , except by sheer chance), fine.
If not, do the musical chairs game:switch right/left a couple until you get a match.
Wit the bias balancing pot set to middle, of course, so you are actually matching thge tubes themselves.
When real close, only then use the pot for final tweaking.
Nothing, for some reason I was assuming that cyclecamper has no scope + dummy load.
Even if does not own them its ok Its more than likely biased on the colder side anyways just plug em in the right sockets fire it up and watch em match sure there is no obvious red-plating or other bad noises etc if you notice anything odd shut her down quickly lol
if some damage occurred in the tubes, drifting apart too much etc you will notice it, and low end is gonna suffer etc you should have some massive low end obviously, if the tubes have weakened its gonna sound weak etc
If you hear any crackling/popping/pinging etc shut it down lol but if those tubes didn't get stressed too bad and hopefully they still draw the right amount of current and at least kinda matched etc should be ok its hard telling if the previous owner cranked it up like that....? lol
well if he did crank it up like that hope he at least had proper impedance match with whatever cab he was running.
I do have a dummy load but sold my oscilloscope, still saving for a better one. I'm surprised to hear so much bashing of the Ruby-labelled JJ's. I thought the JJ's were pretty much the standard for "new" tubes to put in old Fenders now, and what Peaveys come with (some Fenders too??) now. As long as the voltage & current divides reasonably between them and they have similar power I'm OK with it. I really need a 'scope.
Mine were not Ruby, could be that they do a better selection process. Would be interesting how many have to be thrown away when selecting carefully. I do not think that the chineses ones are better per se, it's obviously just a matter of how many the supplier was willing to put in the can.
You can do rudimentary "matching" with the pot by adjusting it to minimal residual hum. Master Volume has to be at zero for this. Works fine if not any of the 6 is significantly out ouf spec.
the ruby JJs I have seen and heard red-plate randomly and many dead out of the box etc and other drifting apart way too much early on, almost seems you will have better luck with the Chinese.
In my opinion get some SED/Svetlana's I have hardly seen any problems with those and they sound good to my ears and seem to hold up for awhile at least. If I had a 6l6 amp again I would put them in it in a heart beat lol or the tungsols or if I was rich RCA blackplates lol
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