2359glenn | studio
May 15, 2024 at 11:55 PM Post #39,991 of 40,062
I’m using two, just like I do with the 6J5’s.
Do you have another amp you can run them in without adapters? I also purchased a quad from that seller 3 or 4 months back and all 4 tubes tested as advertised, and ive ran them with no problems in my amps. If you have another circuit you can try them in without adapters and they still seem to cause issues, id contact seller for replacements, otherwise, we know the issue is isolated to either the adapter or amp, but likely adapter if the amp runs without issue using other tubes.
 
May 15, 2024 at 11:58 PM Post #39,992 of 40,062
I’m using two, just like I do with the 6J5’s.
I use socket savers in all sockets and they lower the temperature of the chassis. In addition, I use two inexpensive 4”USB powered fans - one blowing on the transformer and one blowing on the tubes.
Usually I measure the temperature on the transformer housing which tends to get the hottest. The socket savers and fans lower the chassis temperature at least 10-15C and the transformer housing usually does not exceed 45C, even on a hot summer day.
Anything over 80C is dangerous for the electronics.
 
May 16, 2024 at 10:43 AM Post #39,993 of 40,062
My concern is just that the 6S2S run much hotter than the 6J5s or 6C5Gs do, all else being equal. @g0ldl10n I don't have another amount that I can run them directly in, but I can try the quad in my HA-300, though based on my initial experience with them I'm somewhat hesitant to do so. I may try the other pair in the quad and see if get similar levels of heat with that pair, first.
 
May 16, 2024 at 11:02 AM Post #39,994 of 40,062
My concern is just that the 6S2S run much hotter than the 6J5s or 6C5Gs do, all else being equal. @g0ldl10n I don't have another amount that I can run them directly in, but I can try the quad in my HA-300, though based on my initial experience with them I'm somewhat hesitant to do so. I may try the other pair in the quad and see if get similar levels of heat with that pair, first.
Well, if as you said all things being equal other 6J5 types run considerably cooler, and 6S2S run hot enough to cause concern where normally there is none, does seem quite odd - I have quite the stash of these 6S2S tubes (some of my favorites tbh) and have never experienced such behavior from them.

I do wonder if you were to take infrared thermal readings how much higher they would be from the other 6J5 types - that would give us more of an idea if for some reason they just run a bit hotter, but not to a level of concern, but just guessing here. Dont do anything that you feel might damage your other amp though.
 
Jun 1, 2024 at 11:38 AM Post #39,995 of 40,062
Hey Everyone , if this is the wrong place to put this please let me know. I am just gathering an interest check to see if anyone in the Dallas area is interested in purchasing my GlennOTL amp that I bought from glenn in 2014 it has less then 50 hours of playtime. The layout is similar to this amp below.
1717256283778.png
 
Jun 3, 2024 at 4:10 PM Post #39,997 of 40,062
Hey Everyone , if this is the wrong place to put this please let me know. I am just gathering an interest check to see if anyone in the Dallas area is interested in purchasing my GlennOTL amp that I bought from glenn in 2014 it has less then 50 hours of playtime. The layout is similar to this amp below.1717256283778.png
Hi.. is this a pic of your amp?
 
Jun 3, 2024 at 4:37 PM Post #39,998 of 40,062
@2359glenn. Hope you are doing well & this message finds you as such. Please revert to my DM as its again going the same direction, we discussing design of the amp & you again not responding from quite sometime. Please revert.
Best regards,
Ashwin
 
Jun 17, 2024 at 1:44 PM Post #39,999 of 40,062
I recently discovered the Z2c rectifier manufactured by Siemens, after WWII. It's a German postal tube, with a serial number, like the C3g, but while the C3g is a pentode, the Z2c is a powerful rectifier. The heater draws 4A at 4V and it can provide up to 300mA. So very similar to the Telefunken RGN4004.

2024-06-17 12.55.42.jpg

I am happy to report that it lights up and plays using Deyan's adapter. And it sounds great! :)

2024-06-17 13.39.17.jpg
 
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Jun 17, 2024 at 2:48 PM Post #40,000 of 40,062
I recently discovered the Z2c rectifier manufactured by Siemens, manufactured after WWII. It's a German postal tube, with a serial number, like the C3g, but while the C3g is a pentode, the Z2c is a powerful rectifier. The heater draws 4A at 4V and it can provide up to 300mA. So very similar to the Telefunken RGN4004.

2024-06-17 12.55.42.jpg

I am happy to report that it lights up and plays using Deyan's adapter. And it sounds great! :)

2024-06-17 13.39.17.jpg
And I am happy to both congratulate and to ask if that ADZAM 6SN7GT is made by Philips.
 
Jun 21, 2024 at 8:19 PM Post #40,002 of 40,062
It looks like after 13 years of service my Glenn OTL needs a bit of TLC. I have intermittent crackling and static in both channels that used to stop once some warmth got into everything but now persists at operating temperature and is independent of the tube in use. My first thought was that the sockets needed a cleaning but that didn't help, though to be fair I'm not sure how successful I was at actually cleaning them.

My suspicion is that replacing the sockets might be the cure, but I wanted to ask the group their opinion. If it were something else besides the sockets, like say a capacitor going out of spec, is there a way for a novice like myself who isn't a builder to diagnose this? I'd be grateful for any thoughts/opinions anybody had.
 
Jun 22, 2024 at 1:40 AM Post #40,003 of 40,062
My suspicion is that replacing the sockets might be the cure, but I wanted to ask the group their opinion. If it were something else besides the sockets, like say a capacitor going out of spec, is there a way for a novice like myself who isn't a builder to diagnose this? I'd be grateful for any thoughts/opinions anybody had.

First thing to check with capacitors is to see if the top vent has opened up or is bulging, or if there is any leaks or discoloration around any of the capacitors - those are telltale visual signs of a bad cap. The only way to diagnose the electrical function of capacitors in an amp (if they look visually okay) is to take them out of the circuit and run some tests on them. One of the best ways to test them is with an ESR meter that will measure their capacitance, ESR, and loss tangent. After 13 years though, it's often best to assume that a standard 85C rated electrolytic cap will have degraded to the point of needing to be replaced, and it's often less of a hassle to just replace them than fiddle with testing their properties and finding their datasheet to compare against.

Because the noise is in both channels, that usually tells you that it will be some part that is common/shared between both channels - either a capacitor, resistor, etc., likely in the power supply circuit.
 
Jun 22, 2024 at 8:51 PM Post #40,004 of 40,062
First thing to check with capacitors is to see if the top vent has opened up or is bulging, or if there is any leaks or discoloration around any of the capacitors - those are telltale visual signs of a bad cap. The only way to diagnose the electrical function of capacitors in an amp (if they look visually okay) is to take them out of the circuit and run some tests on them. One of the best ways to test them is with an ESR meter that will measure their capacitance, ESR, and loss tangent. After 13 years though, it's often best to assume that a standard 85C rated electrolytic cap will have degraded to the point of needing to be replaced, and it's often less of a hassle to just replace them than fiddle with testing their properties and finding their datasheet to compare against.

Because the noise is in both channels, that usually tells you that it will be some part that is common/shared between both channels - either a capacitor, resistor, etc., likely in the power supply circuit.
Hi Mischa, appreciate you chiming in! One thing I should clarify (the one time I don't write a book for a post....), the noise is not usually in both channels at the same time. It can be, but I would say most of the time it's in one and tends to bounce from one to the other periodically. I've also had times where I could clear it up by moving or twisting the tube at the base, but not always. It seemed like replacing sockets would be the a good place to start based on this behavior, but there are times when it does feel like something else might be afoot. The amp has a lot of run hours on it now, it's entirely possible it needs attention in a couple of different places. I'm going to take the bottom cover off and see if any of the caps look visibly bad when I get the chance.

I have almost zero soldering skills though, these hands like to tremble and have never been good with precision work, so it remains to be seen if I can talk myself into attempting this on my own.
 
Jun 22, 2024 at 9:41 PM Post #40,005 of 40,062
Hi Mischa, appreciate you chiming in! One thing I should clarify (the one time I don't write a book for a post....), the noise is not usually in both channels at the same time. It can be, but I would say most of the time it's in one and tends to bounce from one to the other periodically. I've also had times where I could clear it up by moving or twisting the tube at the base, but not always. It seemed like replacing sockets would be the a good place to start based on this behavior, but there are times when it does feel like something else might be afoot. The amp has a lot of run hours on it now, it's entirely possible it needs attention in a couple of different places. I'm going to take the bottom cover off and see if any of the caps look visibly bad when I get the chance.

I have almost zero soldering skills though, these hands like to tremble and have never been good with precision work, so it remains to be seen if I can talk myself into attempting this on my own.

Ah, I see, in addition to the sockets potentially being bad it could also be the output caps and/or the resistors hooked up to the tube sockets that may be worth replacing.
 

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