Did some tube swapping

[Jacew]

I replaced tubes in my Egnater Rebel 20 today. Tubes in it were original (previous owner never had opened the back panel), which was apparent looking at 6V6's in. They were completely black! Couldn't see through the glass at all. They still worked though.

Egnater site, manual and threads I've read about the amp all state original tubes in this are JJ's relabeled as Groove Tubes: This had Egnater labeled Ruby tubes though... Switched all (preamp and power amp) to JJ's.

Result wasn't really that good at first: JJ ECC83S seem to have really flat and biting, mid heavy tone, that made the amp lifeless and harsh sounding. I proceeded by switching original Sovteks back to V1 and V2, which got back the tone amp had before I replaced the tubes: Lively and balanced, slightly honky tone.

Since those Sovteks lacked the response of JJ's, and tended to get a bit cloudy with lower input, I decided to try out to add JJ in V1 (preamp) and keep Sovtek in V2 (cathode follower): Turned out to be perfect match! JJ in preamp adds singing clarity and dynamics, with Sovtek in V2 producing the creamy and lively overdrive.

 

[Darg1911]

Re: Did some tube swapping

The 6v6's sound like they were old "black glass" tubes. Several manufacturers made them. Sure you didn't replace a pair of good, old 6v6's?

Here is an example of a JAN RCA black glass 6v6gt

 

[Jacew]

Re: Did some tube swapping

The 6v6's sound like they were old "black glass" tubes. Several manufacturers made them. Sure you didn't replace a pair of good, old 6v6's?

Never heard of those.

They have Egnater and Ruby tubes printed all over them, so I'm sure they're nothing special.

I'm not sure if the 6V6's particularly we're in bad shape, but volume was already faltering so either tube set of power amp was finished.

EDIT: Ruby tubes do apparently have black glass from factory :smack:

 

[FuseG4]

Re: Did some tube swapping

The Ruby 6v6 also has smoked glass so they will normally look black like some vintage tubes.

 

[Darg1911]

Re: Did some tube swapping

I see that now. I didn't know that there were any new production black glass 6v6's.

 

[dystrust]

Re: Did some tube swapping

My Tweaker 15 had the stock Ruby 6V6 / Sovtek 12AX7A combo. One of the 6V6s died, so I replaced them with a pair of JJs which sounded dramatically better. The Sovtek pres aren't horrible, but they're not great either; rather bland. I'm planning to try a Tung Sol in V1 once I have the funds to order more.

I know that Sovteks aren't a great cathode follower in Marshalls (I've had a decent number die there), but is that true for all amps?

 

[FuseG4]

Re: Did some tube swapping

My Tweaker 15 had the stock Ruby 6V6 / Sovtek 12AX7A combo. One of the 6V6s died, so I replaced them with a pair of JJs which sounded dramatically better. The Sovtek pres aren't horrible, but they're not great either; rather bland. I'm planning to try a Tung Sol in V1 once I have the funds to order more.

I know that Sovteks aren't a great cathode follower in Marshalls (I've had a decent number die there), but is that true for all amps?

Any cathode follower position can eat up modern tubes that have longer plates and spiral filaments, so the Sovtek LPS and JJ ECC803. the tung sol and mullard Ri both don't do that great there as well even with the tung sols plates being shorter. It's something to do with something called cathode/heater differential and modern tubes with spiral filaments seem to have dodgy specs here.

Also the tweaker has no cathode follower so use what you like.

 

[dystrust]

Re: Did some tube swapping

Any cathode follower position can eat up modern tubes that have longer plates and spiral filaments, so the Sovtek LPS and JJ ECC803. the tung sol and mullard Ri both don't do that great there as well even with the tung sols plates being shorter. It's something to do with something called cathode/heater differential and modern tubes with spiral filaments seem to have dodgy specs here.

I've been told by numerous sources that all New Sensor tubes (Sovtek, EHX, Tung-Sol, Mullard RI, Svetlana, etc) have spiral filaments, so they shouldn't be used as a cathode follower. I used to swear by EHX, but have had issues with rather poor life in my 2555's CF.

Lately I've been using Shuguangs there, which is about the only thing I like them for. At least now I have a use for all of those Chinese 12AX7s that have been filling my spare tubes box.

Also the tweaker has no cathode follower so use what you like.

Cool, thanks. I was under the impression that the preamp tubes in the Tweaker used the same layout as my Jubilee or other older Marshalls. It turns out that V2 is for the effects loop, so just about anything should be fine there. For anyone interested, a tube chart for the Tweaker 15 can be found here.

 

[FuseG4]

Re: Did some tube swapping

yeah the chinese tubes sometimes make little pop and tick sounds with my amps but, you get used to their sound, they're pretty balanced, reliable, they can take a beating in combo amps. They are a safe bet when everything else gives you problems.

I had a tweaker 15 a long time ago, I traded my DSL50 head for a brand new tweaker and some cash cuz the DSL had to be so loud before it gave up the goods.
The Tweaker I found a little spongey sometimes but it was a real swiss army knife, the guys at the shop i bought it from all called it the poor man's mesa.

I used Sylvania 6v6 GTA when I had the tweaker, clear glass, grey plates, full tube base not the coin bases. They sounded really good and were inexpensive as far as old stock. V1 I had matsu$hita 12ax7. Sounded pretty warm and clear

the JJ 6v6 in my Super Sonic feels very solid big but I'm looking for creamier, earlier power tube breakup and JJs break up late and have more bass than other 6v6 types. Every time I've used JJ 6v6 it makes the amp feel a little "stiff" to me but they really last long and I have not been able to make them red plate.

 

[FuseG4]

Re: Did some tube swapping

was looking at the schematic of rebel 20, v1, the one behind the v3 phase inverter, triode V1B is your cathode follower.
What egnater labels v2 on the rebel 20 is the first preamp stage!

 

[dystrust]

Re: Did some tube swapping

yeah the chinese tubes sometimes make little pop and tick sounds with my amps but, you get used to their sound, they're pretty balanced, reliable, they can take a beating in combo amps. They are a safe bet when everything else gives you problems.

I had a tweaker 15 a long time ago, I traded my DSL50 head for a brand new tweaker and some cash cuz the DSL had to be so loud before it gave up the goods.
The Tweaker I found a little spongey sometimes but it was a real swiss army knife, the guys at the shop i bought it from all called it the poor man's mesa.

I used Sylvania 6v6 GTA when I had the tweaker, clear glass, grey plates, full tube base not the coin bases. They sounded really good and were inexpensive as far as old stock. V1 I had matsu$hita 12ax7. Sounded pretty warm and clear

the JJ 6v6 in my Super Sonic feels very solid big but I'm looking for creamier, earlier power tube breakup and JJs break up late and have more bass than other 6v6 types. Every time I've used JJ 6v6 it makes the amp feel a little "stiff" to me but they really last long and I have not been able to make them red plate.

I mainly use my Tweaker for recording clean sounds or as a pedal platform, so the big sound and extra headroom is a plus. I could see how they may not work as well for other sounds.

 

[Jacew]

Re: Did some tube swapping

was looking at the schematic of rebel 20, v1, the one behind the v3 phase inverter, triode V1B is your cathode follower.
What egnater labels v2 on the rebel 20 is the first preamp stage!

Yep. Rebel manual doesn't actually state which is which at all. Tube closest to the input jack is preamp, that I mistook for V1, but Egnater labels it as V2...

http://www.egnateramps.com/download/Rebel20TubeChart.pdf

 

[Jacew]

Re: Did some tube swapping

Any cathode follower position can eat up modern tubes that have longer plates and spiral filaments, so the Sovtek LPS and JJ ECC803. the tung sol and mullard Ri both don't do that great there as well even with the tung sols plates being shorter. It's something to do with something called cathode/heater differential and modern tubes with spiral filaments seem to have dodgy specs here.

Also the tweaker has no cathode follower so use what you like.

Well, I don't have other use for those Sovteks anyway, so same to use them while they last, since they sound good.

What symptoms does it cause there when going out? Loss of gain at least I guess. Extra noises?

 

[FuseG4]

Re: Did some tube swapping

yeah look out for extra noise, pops, ticks, bad or weak guitar sound, increase in microphonics like that sound of shaking a lightbulb when you hit certain notes, or if the amp "sings" at high gain with no guitar plugged in. In my experience, tube tubes I've had go bad usually only failed on half the tube, putting out weak, distorted tone or no sound on that channel.

 

[dystrust]

Re: Did some tube swapping

Any cathode follower position can eat up modern tubes that have longer plates and spiral filaments, so the Sovtek LPS and JJ ECC803. the tung sol and mullard Ri both don't do that great there as well even with the tung sols plates being shorter. It's something to do with something called cathode/heater differential and modern tubes with spiral filaments seem to have dodgy specs here.

I've been doing more research on this topic as I sort out my spare tubes and figure out which ones I need to order more of. It turns out that we've been inadvertently sharing some misinformation. Long plates aren't the issue at all, neither are spiral filaments. The specific issue stems from how New Sensor builds spiral filament tubes. The Sovtek 12AX7LPS has a spiral filament, as do the Svetlana, EHX, Mullard, and Tung-Sol so they should be avoided as cathode followers. The Sovtek 12AX7WA, WB, & WC don't have spiral filaments, so they should be fine per New Sensor here.

Savage Amps uses JJ ECC83s in the cathode follower position of their amps, and that tube has a spiral filament. The ECC803 is essentially a long plate version of the same tube, so it should work as well though I don't see a specific reason to use one there. Generally speaking long plate tubes work best as a phase inverter and can tend to be microphonic when used as a gain stage.

The best information I've been able to find regarding specific tubes for cathode followers is here.

 

[Darg1911]

Re: Did some tube swapping

The JJ ECC83s does have a spiral filament (the S in JJ tubes stands for spiral filament). And, I believe that you are right that the problem isn't the spiral filament itself. It's a problem with those New Sensor tubes, or how they are designed/built.
The JJ 803s however is not just a long plate version of the 83s. The ECC83's have a different plate structure. Kind of like a frame grid. They remind me of 6DJ8's and 6922's. I believe they are supposed to be copies of the original Tesla tubes.

 

[dystrust]

Re: Did some tube swapping

The JJ ECC83s does have a spiral filament (the S in JJ tubes stands for spiral filament). And, I believe that you are right that the problem isn't the spiral filament itself. It's a problem with those New Sensor tubes, or how they are designed/built.
The JJ 803s however is not just a long plate version of the 83s. The ECC83's have a different plate structure. Kind of like a frame grid. They remind me of 6DJ8's and 6922's. I believe they are supposed to be copies of the original Tesla tubes.

I've heard the same thing about the design of the JJ ECC83. I've seen the JJ ECC803 advertised as a long plate version of the ECC83, and I probably read a bit too much into that. I wouldn't use an 803 as a cathode follower as they're significantly more expensive than an ECC83 and shouldn't provide any sort of tonal benefit.

 

[Jacew]

Re: Did some tube swapping

I've been doing more research on this topic as I sort out my spare tubes and figure out which ones I need to order more of. It turns out that we've been inadvertently sharing some misinformation. Long plates aren't the issue at all, neither are spiral filaments. The specific issue stems from how New Sensor builds spiral filament tubes. The Sovtek 12AX7LPS has a spiral filament, as do the Svetlana, EHX, Mullard, and Tung-Sol so they should be avoided as cathode followers. The Sovtek 12AX7WA, WB, & WC don't have spiral filaments, so they should be fine per New Sensor here.

Savage Amps uses JJ ECC83s in the cathode follower position of their amps, and that tube has a spiral filament. The ECC803 is essentially a long plate version of the same tube, so it should work as well though I don't see a specific reason to use one there. Generally speaking long plate tubes work best as a phase inverter and can tend to be microphonic when used as a gain stage.

The best information I've been able to find regarding specific tubes for cathode followers is here.

Really good info. Egnater stock are 12AX7WB, so they're fine after all there:

The 12AX7WB has about 6% more gain than the 12AX7WA and a slightly darker sound signature, which is great for smoothing out harsh sounding amplifiers

Sounds exactly what I was hearing as well.

 

[FuseG4]

Re: Did some tube swapping

I heard that the WC is the same as WB but selected for noise/microphonics, any idea if this is true, while we're discussing Sovteks?

 

[Darg1911]

Re: Did some tube swapping

The WC is supposed to have matched triodes. Recommended for phase inverters (by New Sensor at least). I'm thinking that the WA,WB and WC are probably all made the same and tested afterwards then marked as appropriate. I read somewhere that, in general, triodes with balanced sections tend to be more consistent with regards to gain and lower noise and microphonics. That would seem to indicate that overall quality is better when the tube comes off the line with the sections being close. That doesn't mean that the tube sounds good ...