[Xcalibur255]

Unfortunately you have found the downside to having a setup that uses a large number of tubes. Getting everything quiet is a patient process of trial and error. I might suggest gently (very gently ) tapping each one of your tubes with a wooden pencil with your headphones on (and the amp powered up) to see what kind of microphonics/noise each is emitting. The major offenders will become obvious pretty quickly.

This is why I basically stopped tube rolling. It stopped being fun and started becoming stress. Once you find a combination you like that works just set the cruise control and leave it in the amp. It will be years before you actually need to replace them because they are worn out (unless you use your amp all day every day).

I'm not very popular around here for stating that having a gazillion tube rolling options is a double-edged sword, but so far I've seen several people buy and then sell their amp because they were intimidated by the amount of choices or were stressed out about finding the "perfect" combo. I can't be completely talking out my ass if it's causing people to walk away.......

I think the original configuration of this amp is still a great sweet spot and highlights the strengths of the KISS ideology. 3DG4 for the rectifier, no need to mess around with anything else there. You can basically start and end with the Brimar 13D1 for a driver for 90% of headphones and music genres. Track down a quiet pair of 6520s for outputs and voila you have a great sounding amp that works well with a variety of headphones. If the 6520 is proving hard to find then any 6AS7 type that isn't noisy is not going to do you wrong at the end of the day.

 

[2359glenn]

So the day has come - my new GOTL arrived a few days ago, but first now I have been able to spend time with it.

This amp is totally different to what I am used to (Little Dot MKIII, Feliks Audio Elise and Euforia). It likes different tubes and tube combinations and headphones compared to the other amps, and it is so much more sensitive, like a tube magnifying glass.
If a tube isn't just perfect it will let you know. Loudly.
Started out with 6 x 6BX7. How do you figure out a bad tube among 7? In addition, when turning on the amp, there was a whole plethora of sounds that I did not hear before: pops, ticks, tinkling, howling and something that sounded like crumpling cellophane paper. And microphonics - just touching the volume knob sent the speakers into a tizzy....( Used a Tung Sol 6F8G as driver)
Oh my gosh, what did I get myself into? How can I find the offending tubes?
At first I just shook my head, then shut the thing off and went to sleep for the night. Yeah - that's the punishment for buying bargain lots of mixed tubes 6BX7 - GE, Philco (Sylvania) and RCA.
OK - next day: Time to try again. Looked over the tubes, checked for corrosion on the pins. And discovered that all of the 6BX7 tubes, no matter what brand, were made by GE. The sandblasted dots are the telltale signs.
Turned on the amp, and based on JV's advice, I just let it sit 20 minutes to warm up without headphones or speakers plugged in - the amp has to keep the pops and ticks to itself....
Turned it on with my $12 headphones plugged in. Just in case. Much more quiet, but not good. Used the balance control to confirm that the noise was in one channel. At least I just need to check out three instead of six tubes.
Tried tapping on the tubes and found one offender. Luckily, I have eight 6BX7, and put in a different one. Finally quiet. Until I touched the volume knob. Microphonics galore - must be the driver tube. Tapped on the driver tube - ouch! Tapped on the chassis, tapped on the volume knob - NYET. How can such a gorgeous looking tube misbehave?

Luckily I have another rebranded one (both are ladder plate, not RP). It did rattle, but I put it in, and no microphonics.
Finally, the GOTL showed what it can do - the best sound I have heard to date. Full bodied, great bass slam and very natural sounding - it just sounds right.
I am just getting used to the amp now. Decided on a very simple set up - a Sylvania 6SN7WGT and a pair of Cetron 6336B. Them big tubes get superhot - measured over 350F! Amazing that the chassis does not have any ventilation holes and only gets fairly warm but not hot with these tubes. As ugly as they are, I am using the socket savers to cool down the chassis (and I turned on my fan for the 6336s - the chassis is barely warm with the fan pulling away hot air).
This combination is totally silent at even loud normal listening levels and very little hum even at full tilt.
And here is today's question: How can I save the TS microphonic tube from the garbage heap? Any tricks to get rid of the microphonics? (The less expensive the better.) I read about high temperature silicon tube rings, but I'll rather buy them from a car parts shop than a Hi Fi web site - any suggestions? Or something else - heard about heat resistant silicone tape as well.
Have fun!

Allot of 6F8G tubes tend to be micro phonic nothing you can really do about it other then trash it.

 

[mordy]

Unfortunately you have found the downside to having a setup that uses a large number of tubes. Getting everything quiet is a patient process of trial and error. I might suggest gently (very gently ) tapping each one of your tubes with a wooden pencil with your headphones on (and the amp powered up) to see what kind of microphonics/noise each is emitting. The major offenders will become obvious pretty quickly.

This is why I basically stopped tube rolling. It stopped being fun and started becoming stress. Once you find a combination you like that works just set the cruise control and leave it in the amp. It will be years before you actually need to replace them because they are worn out (unless you use your amp all day every day).

I'm not very popular around here for stating that having a gazillion tube rolling options is a double-edged sword, but so far I've seen several people buy and then sell their amp because they were intimidated by the amount of choices or were stressed out about finding the "perfect" combo. I can't be completely talking out my ass if it's causing people to walk away.......

I think the original configuration of this amp is still a great sweet spot and highlights the strengths of the KISS ideology. 3DG4 for the rectifier, no need to mess around with anything else there. You can basically start and end with the Brimar 13D1 for a driver for 90% of headphones and music genres. Track down a quiet pair of 6520s for outputs and voila you have a great sounding amp that works well with a variety of headphones. If the 6520 is proving hard to find then any 6AS7 type that isn't noisy is not going to do you wrong at the end of the day.

Hi X255,
Thanks for your comments - I can certainly see your points. However, there is so much gain in my system that even with very low volume settings on my preamp and GOTL I get very good volume, and at these low volume settings hum isn't a problem.
In addition, I generally don't find tube rolling stressful, and rather enjoy trying different things. Of course, there are times when you get enough, but on the whole I look at it as an interesting and rewarding experience, especially finding inexpensive, good sounding tubes (and finding expensive tubes at bargain prices, but that's another story).
And as you say, when you find what you really like, you just leave the same tubes in, sit back, and enjoy listening.
Re keeping it simple, I choose not to have an option of rectifier rolling and just going with HEXFRED ss rectification.
I find it interesting that the same tube that is quiet in a different amp becomes microphonic in the GOTL but I attribute it to the increased sensitivity and performance of the GOTL.
I don't have the 6520, but I have Chatham 6AS7G and TS 5998 in addition to a number of others (Svetlana, GEC, RCA etc). And the Brimar 13D1 is on my list. Funny, can't find much to choose from in 25V dual triodes.

 

[Althalus]

So the day has come - my new GOTL arrived a few days ago, but first now I have been able to spend time with it.

Congrats Mordy, enjoy your gotl.

Thank you for your advice to keep it simple in the beginning.

I choose for the option 3dg4 and plugin hexfred. One additional cause of problems more, although I don't think that the rectifier tube will give any trouble.

Now I'm getting more restless, one amp more finished but still two months before Glenn starts building mine. I'm looking forward to it.

 

[JazzVinyl]

And here is today's question: How can I save the TS microphonic tube from the garbage heap? Any tricks to get rid of the microphonics? (The less expensive the better.) I read about high temperature silicon tube rings, but I'll rather buy them from a car parts shop than a Hi Fi web site - any suggestions? Or something else - heard about heat resistant silicone tape as well.
Have fun!

Very nice post, Mordy

I am with Glenn on this one. The GOTL will bring forth so much goodness with such a variety of SN7's (6/12/25v) why bother trying to get one gorgeous
Tung Sol 6F8G to behave itself?

I like your 6SN7WGT, and bet it sounds very very nice, indeed.

Would be interested in your thoughts regarding the 6336's vs the quiet set of 6BX7's. I never went for the 6336's...too much heat for me

Cheers, Mordy! Hope _you_ have fun trying all your many drivers in your beautiful GOTL.

 

[whirlwind]

Congrats Mordy!

 

[leftside]

Congrats Mordy. Another one off the list, which means all of us on the list now move up a place!

Regarding the 6F8G. I've never had so many microphonic problems as I have with this particular tube.

Regarding the 6BX7 or 6BL7. These are tough tubes, and as such will often test high even when abused. Yes, sometimes one of them can be noisy - throw them out. I've had better success when I've combined 4 (or 6) with the same matching construction - i'e top square getter vs top circle getter, side square getter vs side circle getter, flat plates vs "t" plates, 3 mica vs 2 mica, etc. Also even some of the plates have slight differences - 3 holes vs 2 holes.

I have 29 tubes combined in my system that uses the Glenn 300B, and it's perfectly silent when using the DAC. Sure, it might need a few minutes to settle down (tubes with slight popping), but that's not a problem.

 

[2359glenn]

Congrats Mordy. Another one off the list, which means all of us on the list now move up a place!

Regarding the 6F8G. I've never had so many microphonic problems as I have with this particular tube.

Regarding the 6BX7 or 6BL7. These are tough tubes, and as such will often test high even when abused. Yes, sometimes one of them can be noisy - throw them out. I've had better success when I've combined 4 (or 6) with the same matching construction - i'e top square getter vs top circle getter, side square getter vs side circle getter, flat plates vs "t" plates, 3 mica vs 2 mica, etc. Also even some of the plates have slight differences - 3 holes vs 2 holes.

I have 29 tubes combined in my system that uses the Glenn 300B, and it's perfectly silent when using the DAC. Sure, it might need a few minutes to settle down (tubes with slight popping), but that's not a problem.

I am building another 300B amp yours was the last one I built. This one will use HEXFRED rectifiers and a timer for soft start of B+. I would prefer to use the 42EC4 Damper diodes
but Tony had one fail and the circuit breaker in his house blew before the 2 amp fuse in the amp did. I never had a problem with these tubes before just a bad tube and maybe
a weak breaker. Now this tube has a bad rep. I did have a 6EC4 fail really the same tube but it was in a SV572-3 amp running at 1200 volts that would be 2400 or more PIV
across the tube. Only the fuse in the amp blew.
Will see how this one sounds all else will be the same with C3g drivers. Making the most neutral sounding amp. Maybe better sounding who knows.

I am waiting for the new WE300Bs to be on sale I need a pair as the filament in one of my KR globe 300Bs burned out now have one KR and one Sovteck
TAKs are way to expensive.

 

[Phantaminum]

Purchased some tubes from a UK seller who listed them as B36. I can imagine that these are relabeled Phillips 12sn7gts but sold as Mullard/Osram. Along the same type as the Pope 6sn7s but one is a gray plate and the other is a black plate. They are obviously not real B36 as those have totally different insides. What do you guys think? @gibosi

 

[leftside]

I am building another 300B amp yours was the last one I built. This one will use HEXFRED rectifiers and a timer for soft start of B+. I would prefer to use the 42EC4 Damper diodes
but Tony had one fail and the circuit breaker in his house blew before the 2 amp fuse in the amp did. I never had a problem with these tubes before just a bad tube and maybe
a weak breaker. Now this tube has a bad rep. I did have a 6EC4 fail really the same tube but it was in a SV572-3 amp running at 1200 volts that would be 2400 or more PIV
across the tube. Only the fuse in the amp blew.
Will see how this one sounds all else will be the same with C3g drivers. Making the most neutral sounding amp. Maybe better sounding who knows.

I am waiting for the new WE300Bs to be on sale I need a pair as the filament in one of my KR globe 300Bs burned out now have one KR and one Sovteck
TAKs are way to expensive.

"Neutral" is the perfect expression for the 300B amp. I have a bunch of tubes waiting for when you get around to my GOTL.

Let's see how expensive the new WE300Bs are...

 

[gibosi]

Purchased some tubes from a UK seller who listed them as B36. I can imagine that these are relabeled Phillips 12sn7gts but sold as Mullard/Osram. Along the same type as the Pope 6sn7s but one is a gray plate and the other is a black plate. They are obviously not real B36 as those have totally different insides. What do you guys think? @gibosi

They don't look like any GEC B36 I have seen before. And while I seen Fivre 12SN7 labeled as GEC B36, they don't look like Fivre either. I am inclined to think that these were manufactured by Philips, either in Eindhoven or Bruxelles. If so, there should be a production code printed on the bottom around the pins, similar to the picture below. However, instead of "r9", which is for a 6SN7GT, it should read "0K" for a 12SN7GT. In the second line, "4" indicates Eindhoven where as "L" would indicate M.B.L.E., Bruxelles (Mazda). So do you see such a code?

 

[Phantaminum]

They don't look like any GEC B36 I have seen before. And while I seen Fivre 12SN7 labeled as GEC B36, they don't look like Fivre either. I am inclined to think that these were manufactured by Philips, either in Eindhoven or Bruxelles. If so, there should be a production code printed on the bottom around the pins, similar to the picture below. However, instead of "r9", which is for a 6SN7GT, it should read "0K" for a 12SN7GT. In the second line, "4" indicates Eindhoven where as "L" would indicate M.B.L.E., Bruxelles (Mazda). So do you see such a code?

The Mullard has a code at the bottom: OK3 L81
The Osram doesn't have any code...

Bottom Getters are also at different angles. The Mullard is a square getter that's horizontal while the Osram is vertical. Mullard has teeth on the bottom mica while the Osram doesn't. Hmm.

 

[gibosi]

The Mullard has a code at the bottom: OK3 L81
The Osram doesn't have any code...

Bottom Getters are also at different angles. The Mullard is a square getter that's horizontal while the Osram is vertical. Mullard has teeth on the bottom mica while the Osram doesn't. Hmm.

With later tubes, Philips moved the production code from the bottom of the base to the side of glass bottle, near the base. If you can't find any codes, either they have been rubbed off or it wasn't manufactured by Philips....

 

[2359glenn]

The Mullard has a code at the bottom: OK3 L81
The Osram doesn't have any code...

Bottom Getters are also at different angles. The Mullard is a square getter that's horizontal while the Osram is vertical. Mullard has teeth on the bottom mica while the Osram doesn't. Hmm.

The real ones should have rounded or oval plates. The 13D1s I just got are lie that .

 

[Phantaminum]

With later tubes, Philips moved the production code from the bottom of the base to the side of glass bottle, near the base. If you can't find any codes, either they have been rubbed off or it wasn't manufactured by Philips....

The real ones should have rounded or oval plates. The 13D1s I just got are lie that .

Think I'll be returning these for a refund. I wouldn't have minded if I could verify that both were Philips made tubes but the Osram looks to be a fake which doesn't instill much confidence in me. Thanks for getting back to me guys and I'll buy a few 13D1s if I can find some.