Hi
I have a problem, any help appreciated!
Im bit of a newbie when it comes to tubes, and i bought wavac md-300b amplifier.
It works perfectly with 6y6 tubes, but:
-I was told that i could try 6Y6G tubes as a substitute for 6Y6, but when i try them there is loud popping noises from both channels (even if volume is zero)
and finally a loud hum from both speakers.
So was i given bad information, or is the tube faulty?
Link to video:
I have a problem, any help appreciated!
Im bit of a newbie when it comes to tubes, and i bought wavac md-300b amplifier.
It works perfectly with 6y6 tubes, but:
-I was told that i could try 6Y6G tubes as a substitute for 6Y6, but when i try them there is loud popping noises from both channels (even if volume is zero)
and finally a loud hum from both speakers.
So was i given bad information, or is the tube faulty?
Link to video:
According to Radiomuseum 6Y6 and 6Y6G are identical, there is not even a metal version of 6Y6G (which sometimes has a different pin for the grounding of the case).
What prompted you to change the tubes? What is the provenance of the new tubes? Are you comfortable collecting the DC voltages to ground from each tube pin?
What prompted you to change the tubes? What is the provenance of the new tubes? Are you comfortable collecting the DC voltages to ground from each tube pin?
A couple of the old 6Y6G data sheets show either "NC" or "S" at pin #1. If the amp in question uses pin #1 as a tie point for something, this could be a problem.
Tung-sol - https://frank.pocnet.net/sheets/127/6/6Y6G.pdf
Sylvania - https://frank.pocnet.net/sheets/121/6/6Y6G.pdf
jeff
Tung-sol - https://frank.pocnet.net/sheets/127/6/6Y6G.pdf
Sylvania - https://frank.pocnet.net/sheets/121/6/6Y6G.pdf
jeff
Only if you have one. The frank.pocnet site does not list any metal version of the 6Y6.
Check that there are no connexions to the socket pin One, Most of the metal tubes used Pin One as a connexion to the metal enclosure
The exceptions are the 6SXN group.
But all AOK otherwise,
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-I wanted to have bit more body to the sound, so i was told try G version of 6y6..
They are from ebay seller and supposed to be NOS. No im not comfortable with the hum and crackling sound, i am comfortable with earlier 6y6 sound that is completely silent though and trying to see do i return this 6y6g tube, or is it my amplifier in this case..
I would return them for a refund, and use the original tubes. It's obvious the "G" version doesn't work in your amp.
jeff
Have you checked what's connected to pin 1? Amplifier off of course and wait a few minutes. No need to touch anything, just tell us if there are any wires connected to pin 1. Pin 1 is the first pin going round clockwise from the slot for the tube key, that's looking at the underside of the socket. The G version may sound good in theory, but you'd need to know what's happening at the socket. If there's nothing connected to pin 1, then return the tubes.
The tube is bad,
Or,
The tube pins are oxidized (check for that),
Or,
The socket is oxidized and/or the socket fingers are spread (check for that).
Pin 1 is either a Shield internally connected inside the tube; Or Pin 1 is NC (No Connection internally in the tube).
It is doubtful that either a shield, or NC would cause the amplifier to oscillate; but it is possible.
So, Please post a complete and accurate schematic (that is worth 1,000 words; and is worth 100 Posts if an oscillation is the problem).
Ask the vendor this question:
Is the 6Y6G he sent you, New Old Stock (NOS), Or is it Used?
Put your original tubes back in, if it works with the original tubes, I would send the "new" ones back to him for a refund.
Or,
The tube pins are oxidized (check for that),
Or,
The socket is oxidized and/or the socket fingers are spread (check for that).
Pin 1 is either a Shield internally connected inside the tube; Or Pin 1 is NC (No Connection internally in the tube).
It is doubtful that either a shield, or NC would cause the amplifier to oscillate; but it is possible.
So, Please post a complete and accurate schematic (that is worth 1,000 words; and is worth 100 Posts if an oscillation is the problem).
Ask the vendor this question:
Is the 6Y6G he sent you, New Old Stock (NOS), Or is it Used?
Put your original tubes back in, if it works with the original tubes, I would send the "new" ones back to him for a refund.
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Before anyone is prematurely casting aspersions on the seller, wait to find out what, if anything, is connected to the socket pin 1 for each tube, and also look and find out if the 6Y6s in question have a pin 1 installed in their bases.
Not all 6Y6 variants have a pin 1. Some say S some say NC but check for the pin please.
These are things anyone using variants of tubes should be checking and come to know with time.
Not all 6Y6 variants have a pin 1. Some say S some say NC but check for the pin please.
These are things anyone using variants of tubes should be checking and come to know with time.
opcom,
The pinout diagram of a 6Y6-G, 6Y6-GA, and 6Y6-GT shows a pin with S/NC (Shield/No Connect), it does Not mean that there is no pin there on the header.
It simply means that the NC pin, if present, is not connected Internally to anything.
Having a NC pin gives strength to the tube mount.
Example:
My KT66 tubes Do have pin 1 on the header (NC), but that pin is Not connected to anything Internal, and is not connected to the metal shield outside of the glass.
However, there is No Pin 6 (NP) of my KT66 tubes. That causes less capacitance between pin 5 control grid and pin 7 filament.
Anybody . . . If you have a Metal Cased 6Y6, then insure it.
It extremely rare, probably it is Never-manufactured-ium.
It is a valuable Museum Piece!
$$$
The pinout diagram of a 6Y6-G, 6Y6-GA, and 6Y6-GT shows a pin with S/NC (Shield/No Connect), it does Not mean that there is no pin there on the header.
It simply means that the NC pin, if present, is not connected Internally to anything.
Having a NC pin gives strength to the tube mount.
Example:
My KT66 tubes Do have pin 1 on the header (NC), but that pin is Not connected to anything Internal, and is not connected to the metal shield outside of the glass.
However, there is No Pin 6 (NP) of my KT66 tubes. That causes less capacitance between pin 5 control grid and pin 7 filament.
Anybody . . . If you have a Metal Cased 6Y6, then insure it.
It extremely rare, probably it is Never-manufactured-ium.
It is a valuable Museum Piece!
$$$
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I'm aware of the variants as well as the practice of placing pin 1 where it isn't used electrically. My point is simply that if the tube has a pin 1, and it is connected to and internal shield, and the amp uses pin 1 for some purpose, that it could cause the problem even if the tube is perfect.
matsurus,
When you check the amplifier's socket's Pin # 1 tab, to see if it is connected, here is another check:
Measure the voltage at Pin # 5, the control grid.
Let us know what that voltage is, please.
If there is very much voltage there, it means one of three things:
Gassy tube
DC coupling to the grid, Pin # 5
Leaky Coupling cap to the grid Pin # 5
I have seen an instance where Gas in a tube caused an oscillation.
When you check the amplifier's socket's Pin # 1 tab, to see if it is connected, here is another check:
Measure the voltage at Pin # 5, the control grid.
Let us know what that voltage is, please.
If there is very much voltage there, it means one of three things:
Gassy tube
DC coupling to the grid, Pin # 5
Leaky Coupling cap to the grid Pin # 5
I have seen an instance where Gas in a tube caused an oscillation.
I think it is also possible for tubes that have not been used for many decades to have had a trace of leakage and require the getter to do its work for a while to restore the proper working conditions.
I have a lot of tubes to sell at some point, and the ones I have sold I have always endeavoured to sell them tested, ideally with a curve tracer output in the advert. The old ones, first time out of their boxes, very rarely behave the way they should. Also in the old days tolerances could be 50% (that was the definition of 'good' in the instructions of my Funke W.20 for certain vintages of tubes).
A set of DC voltages to ground for all the tube pins is a good way to isolate an issue.
I have a lot of tubes to sell at some point, and the ones I have sold I have always endeavoured to sell them tested, ideally with a curve tracer output in the advert. The old ones, first time out of their boxes, very rarely behave the way they should. Also in the old days tolerances could be 50% (that was the definition of 'good' in the instructions of my Funke W.20 for certain vintages of tubes).
A set of DC voltages to ground for all the tube pins is a good way to isolate an issue.
My Tung Sol data book shows the sheets for 6Y6GA with a 7 pin short octal base - pin 1 is no connection, and pin 6 is absent.
Sorry for the bad pic - it's too much work to pull out the individual pages and scan. It's a four volume set, and each volume is 3 or 4 inches thick.
Interestingly, the sheet mentions 6Y6G, but not 6Y6GT. I don't think I've ever seen a metal 6Y6. The other three variants are common - I found examples of each here at my office - my real tube stash is in my warehouse across town. It would be interesting to see a picture of metal 6Y6.
Win W5JAG
Sorry for the bad pic - it's too much work to pull out the individual pages and scan. It's a four volume set, and each volume is 3 or 4 inches thick.
Interestingly, the sheet mentions 6Y6G, but not 6Y6GT. I don't think I've ever seen a metal 6Y6. The other three variants are common - I found examples of each here at my office - my real tube stash is in my warehouse across town. It would be interesting to see a picture of metal 6Y6.
Win W5JAG
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