Learn Me About Tubes

[NSYMCE]

Unlike you I'm not qualified to change the cathode resistor itself. That's your game Charley. I have to opt for the tube change. But another question might be if in doing so would that in any way alter is usefulness as a cathode biased amp?

Unfortunately most of the players in this world are also not qualified to re-engineer their amps other than via tube swaps and/or speaker swaps. While the Tweakers output transformer doesn't change the internal design of the circuits for each voicing does and while no one will ever accuse them of being a dead nuts copy of the true voicings it allows it emulates them well enough to satisfy the user.

That said if you want an 18w Marshall buy one or a 22w Fender Blackface Deluxe, or a VOX AC15 because it will never satisfy any true aficionado of those amps. That wasn't it purpose any more than a pedal can get you what a cranked amp can really sound like. Unless it's the "real deal" all else is a compromise of one sort or another.

I think amps like the Univalve are totally keWl and who cares if they're not really optimized for any particular tube. BTW, cathode bias doesn't mean "universal" in any way either, especially these days with so many janky power tubes being out there.

And nah, I don't advocate end users tweaking basic circuit parameters, especially if a simple tube type swap already works for them. I had a bandmate who really wanted some "Derek Trucks mods" to his Blackface Vibrolux Reverb, and he put me in touch with Derek's amp tech. I did the mods reluctantly and the amp was pretty much only good for one slide voicing, a la guess who. When my friend went to sell the amp none of the local hotshots who could actually afford it liked it at all, which didn't exactly make me look good. Pretty sure I lost some business over that, but so it goes.

 

[Jim C]

Was the mod a mid range boost and higher gain (distortion earlier relative to volume)?

 

[soulman]

I think amps like the Univalve are totally keWl and who cares if they're not really optimized for any particular tube. BTW, cathode bias doesn't mean "universal" in any way either, especially these days with so many janky power tubes being out there.

And nah, I don't advocate end users tweaking basic circuit parameters, especially if a simple tube type swap already works for them. I had a bandmate who really wanted some "Derek Trucks mods" to his Blackface Vibrolux Reverb, and he put me in touch with Derek's amp tech. I did the mods reluctantly and the amp was pretty much only good for one slide voicing, a la guess who. When my friend went to sell the amp none of the local hotshots who could actually afford it liked it at all, which didn' exactly make me look good. Pretty sure I lost some business over that, but so it goes.

Thanks Charley. One reason I chose those NOS Tung-Sol 5881s is they tend to work well with the bias of the amp.

I was fortunate enough to have a jam buddy who had a whole lot of tubes he'd scored back in the days when GC would just put them out on a bargain table so I was able to use those to experiment with. Then another owner suggested he'd really liked the 5881s in his amp so I found a decent pair from a seller and tried them. I liked them enough to buy another pair as backup because I have no intention of ever selling the amp. It's perfect for what I need in a tube amp.

 

[NSYMCE]

Thanks Charley. One reason I chose those NOS Tung-Sol 5881s is they tend to work well with the bias of the amp.

I was fortunate enough to have a jam buddy who had a whole lot of tubes he'd scored back in the days when GC would just put them out on a bargain table so I was able to use those to experiment with. Then another owner suggested he'd really liked the 5881s in his amp so I found a decent pair from a seller and tried them. I liked them enough to buy another pair as backup because I have no intention of ever selling the amp. It's perfect for what I need in a tube amp.

Real 5881s are awesome, probably my favorite power tube for my own guitar wants and needs. The totally not real so-called 5881 Sovtek military servo tubes gave them a bit of a bad rep unfortunately. They definitely were, ermm, bomber though!

 

[soulman]

Real 5881s are awesome, probably my favorite power tube for my own guitar wants and needs. The totally not real so-called 5881 Sovtek military servo tubes gave them a bit of a bad rep unfortunately. They defintely were, ermm, bomber though!

Mine are all US made versions and they weren't exactly cheap but then I don't blow through tubes that often.

 

[Jim C]

Tung-Sol was originally made in Newark New Jersey in the 20's and ended up with the final version of their name in 1951.
They were a premier tube maker in the US from the 50's - 70's.
AFAIK, everything after that was another version of a Chinese firecracker manufactured by someone else.

"Tung-Sol was privately held and run like a laboratory. This gave Tung-Sol vacuum tubes a reputation of having some of the best metallurgy and chemistry in actual production.[4] The Tung-Sol brand name is now owned by the New Sensor Corporation, the same company that owns the brands Sovtek and Electro-Harmonix.[5]"

Similar situation for Mullard:

Mullard brand name[edit]​

Philips continued to use the brand name "Mullard" in the UK until 1988. Mullard Research Laboratories in Redhill, Surrey then became Philips Research Laboratories. As of 2007, the Mullard brand has been revived by Sovtek, producing a variant of the ECC83 and EL34.

NoS isn't a guarantee of quality without the date of manufacture.

 

[soulman]

True, the newer production is made in Russia by New Sensor. I've used those as well. They're still very good tubes.

The 5881s I have are all US made early 70s vintage not by a Chinese firecracker manufacturer.

 

[NSYMCE]

Was the mod a mid range boost and higher gain (distortion earlier relative to volume)?

It entailed swapping in two pretty dark sounding Weber DT model tens, and larger value coupling caps which would potentially do what you mentioned. And maybe something with the treble control corner frequency and/or bright switch IIRC. It was just dark and kind of lifeless compared to the classic Fender thing, especially compared to my Fender 30 that I converted to BF/SF Vibrolux Reverb spec around that time. It did that one DT thing well, but my friend doesn't really even play slide guitar...go figure. He's a fantastic drummer by now though, he's thrown a ton of work at that over the years and studied with Brian Blade quite a bit.

 

[Jim C]

True, the newer production is made in Russia by New Sensor. I've used those as well. They're still very good tubes.

The 5881s I have are all US made early 70s vintage not by a Chinese firecracker manufacturer.

Out of the 40 or so 12AX variants in my stash (taken from old gear / ham fests) are all 60's and 70's vintage.
Not one is made anywhere other than Europe or the US.
I think anything made in Russia or China is fair at best and certainly won't last 50 years. Plus, I'm not buying anything that came from Russia until forever. Fuck those bastards.
At least JJ's come from Slovakia.

 

[NSYMCE]

True, the newer production is made in Russia by New Sensor. I've used those as well. They're still very good tubes.

The original Sovtek 5881WXT withstood higher plate voltages like in a Twin Reverb 135 really well and were standard in Fenders for a while. Fender biased them cold, as they often do, and that didn't help their rep much. They made a little less power than a real 6L6GC so 5881 was kinda sorta a reasonable thing to call it. I think at some point they ported to a different design, not sure if I've ever heard that version though.

My impression is that Shuguang was doing a very good job on the Tube Amp Doctor branded Sino power tubes a few years ago, but of course that factory no longer exists. I'll be revisiting JJ sooner than later, but it's a shame the US distributor is seemingly such an absolute douchenozzle. I can still cop nice NOS tubes locally, but the cost is way outta my comfort zone for the most part.

 

[soulman]

The original Sovtek 5881WXT withstood higher plate voltages like in a Twin Reverb 135 really well and were standard in Fenders for a while. Fender biased them cold, as they often do, and that didn't help their rep much. They made a little less power than a real 6L6GC so 5881 was kinda sorta a reasonable thing to call it. I think at some point they ported to a different design, not sure if I've ever heard that version though.

My impression is that Shuguang was doing a very good job on the Tube Amp Doctor branded Sino power tubes a few years ago, but of course that factory no longer exists. I'll be revisiting JJ sooner than later, but it's a shame the US distributor is seemingly such an absolute douchenozzle. I can still cop nice NOS tubes locally, but the cost is way outta my comfort zone for the most part.

Yeah, what is it like 22w each as opposed to 25w for the 6L6GC or somewhere around there? Of course the Tweaker only puts out 15w but to my ears it's smoother than the Chinese 6v6s that came stock with the amp and maybe I'm gaining a bit more headroom???? I tend to run my amps clean anyway and use pedals for break up but if I open that amp up there's plenty of gain there for it to do it's own things as well. Just can't do it in a multi-tenant building is all.

I got a pretty good deal on the 5881s which is why I bought two pairs but the preamp tubes I bought were older used GE and Sylvanias that tested out good and the RCA was sold as NOS but that may or may not be true. At any rate I got it off an auction and it's worked fine so no sense in worrying about it. I picked up a couple of JAN Phillips 5751s cheap too. It seems that I can get those for much less than 12ax7s or 12at7s. The supply seems to be shrinking.

 

[NSYMCE]

Nice 5751s have been priced very high from my usual suspect list of suppliers for several years now. I can still find good deals on 12AU7s pretty readily though, which are my favorites among the 12A.. nonal preamp tubes for bass duty. Nice NOS 6SL7 and 6SN7 tubes are skyrocketing and half of them seem to be microphonic, effectively doubling my cost. The 12 volt variants are still dirt cheap though and I have several on hand to test out whenever I finally get motivated to complete my 100 watt tube amp build. I finally have a cab now that would work well with that, so maybe I'll still get around to it by year's end.

And then it'll be time to do a new guitar amp build, which will use EL-84s. That should make for a cool change of pace, and give me an excuse to do some new pedal builds, which I have very limited experience in. The online DIY community for pedal builders is insanely cool and that's a big part of why I spend so little time here these days.

 

[armyadarkness]

I don't blow through tubes that often

That's not what I heard

 

[soulman]

That's not what I heard

Try this. Might help.

 

[knuckledust3r]

Thanks for all the help everyone! These arrived today, and I got 'em plugged into both of the amps in question. The Ibanez TSA-5 is a clone of a Fender Champ, but with a built-in Tubescreamer TS9 pedal. The Vox (that started this whole fiasco) is their mid-grade modelling amp from the mid 2000s.

The Ibanez came with Ruby tubes - that was the 12ax7 that I broke trying to install it in the Vox (try both tubes in both amps to see if the problems travel with the tubes - they did). The issue here was that the amp was a floor model when I bought it in 2014, so who knows how long that sat out being used and abused by weedly-weedly shop patrons...not to mention I accidentally left it on for a few months one time on accident. Anyway, a white noise or pink noise developed in the background at all times.

The good news is the background noise subsided with the ol' tube swap! The Raytheons, when compared to the Rubies, seem cleaner and more articulate. The tone is a bit darker, I suppose. I've often disliked these BS "tone words" and meaningless descriptors. When I dimed the Tube Screamer and the amp, things got...fizzy? Like, I could still pick out each note in a chord, but it had a weird hiss. No biggie, I only dimed everything just for teh lulz (and to generate a little bit of that hot tube smell...hot tube smell was FCleff's nickname in college); I never play it in that state because what practical purpose would that serve? I don't know what effect the 6v6 has over the 12ax7, but whatever.

In the ol' Vox, the Raytheon tube fit into the space a whole lot better than the Ruby. The amp came with an Electroharmonix 12ax7, but would distort weirdly whenever a knob was turned or a flip was switched in the modelling section. By swapping the EHX with the Ruby (from the Ibanez), I was able to isolate the fact that the weird distortion followed the EHX tube. But, I don't know WTF happened...the Ruby didn't physically fit into the cramped space, so some pins got bent, and then the glass cracked when I tried to straighten it. The EHX fit, as does the Raytheon. In fact, I don't know if the Raytheon/Baldwin 12ax7 is smaller in stature than the others, but it slipped right in there. I have yet to try this amp out, as I haven't yet put the effort into reassembling the whole thing (the whole amp module has to come out of the cab in order to service the tube).

 

[soulman]

I don't know what effect the 6v6 has over the 12ax7, but whatever.

This one is easy to answer. None. The 12ax7 is a preamp tube that's used to boost the weaker signal coming from the guitar which is then fed via the circuit to the 6v6 which is the main power tube that's doing the heavy lifting as far a amplifying the signal the speaker hears and in turn you hear. If the preamp tube is noisy the power tube will simply amplify that noise along with the signal from the pickups. The quieter running the tube the less noise you get.

https://www.tubesandmore.com/tech-articles/12ax7-comparison-current-made-tubes

Above is a link to a guide to the characteristics of 12ax7 premap tubes including their comparative noise ratings and their gain ratings along with their tonal characteristics. This can sometimes help in the selection of primary preamp tubes for a specific amp or playing style. Higher gain means more output from the preamp tube to drive the power tube harder.

 

[knuckledust3r]

Anyway, more good news. The t00b swap definitely remedied the ills that had befallen the Vox amp.

 

[knuckledust3r]

Almost a year on - the Ibanez TSA-5 with the Raytheon tubes added is still a little bit dark, but either my ears have grown accustomed to it or the amp has settled into the tubes because it doesn't sound as lifeless as it once did. The Vox is still there - similar to the Ibanez sounding a bit darker, it does seem like the Vox has settled in to a little less harsh of a sound with a little more "chew" to it...despite being a solid state modeler with a tube preamp, and unless I'm totally misusing these terms (this is a definite pssibility), you can dig in just a little with the "new" tube.

 

[knuckledust3r]

Bump! I've got a cheap tube-driven preamp on my stereo. Problem is, it's REALLY quiet...I've gotta run the amplifier/receiver at 75 or 80 on the volume knob just to have it be audible. The cheap solid state preamp I have gets LOUD (gotta run it on 15-20 on the volume knob). Would a tube swap give me the volume I want out of the tube preamp, or is that just a tube stereo thing?

 

[4strings]

Maybe, maybe not. It could be bad caps or a hundred other things. Try swapping the tube first then go from there.

Normally I'd start with the schematic which (hopefully) has voltages labeled at various points in the circuit. Start measuring to see if anything is out of whack and troubleshoot.

Tube amp voltages can kill you super dead, beware.