Hello to all, I have a Hughes & Kettner 25th Anniversary guitar amp that came stock with 6n15n-EB tubes and one has a crack in the glass and it still functions but I don't trust it. I bought the amp used from the original owner and it is like new and it has never been apart so it must've come this way from the factory. I understand that these are not EL84 tubes yet H&K says the amp has EL84's. I called H&K to get a replacement and they said to use any EL84 tubes. Terrible customer support lacking any details. They rarely answer email. The earlier versions of this amp both had EL84's in them. I don't know why they used these 6n15n-EB tubes instead of regular EL84's but they do brag about them in their advertisements as hand picked military top drawer tubes, and they do seem to sound pretty good. I would however like to try some EL84's like JJ Teslas to compare the sound but I'm not sure if standard ones can handle the 400V plate voltage that I've read this has. It seems that most standard EL84 tubes can only handle 300V max. I can't find any spec's on the 6n15n tubes to see if they are rated higher than 300V and I don't know what type EL84 tubes the earlier version amps came with. I'd like to know if I can go with standard EL84's or if I have to limit myself to the small amount of higher voltage ones available, or should I just stay with the 6N15N-EB type even though they seem to be difficult to find and maybe not as desirable as EL84's for guitar tone. Thanks for any input.
6P15P-EV is not a god EL84 substitution. The closest replacement for EL84 is 6P14P, or 6P14P-EV. 6P15P-EV seems to be a replacement for EL83, wich has a lower anode dissipation. http://frank.pocnet.net/sheets/113/6/6P14P.pdf http://frank.pocnet.net/sheets/113/6/6P15P.pdf
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That's what's confusing me about this amp. It came with the 6n15n's yet H&K lists them as EL84's and says to use any EL84 tube as a substitute. I'll have to open it up and see if it's wired for a SV83 but I think they just put it in there in place of the EL84. Maybe the Germans are daring.
An EL84 can be a sub for 6n15p (SV-83), but not always the other way around as it is not as robust.
dave
dave
As far as I know this amp is the same exact design as the older versions that came with EL84's. There's no schematics on these so the only way to know would be to trace it out I guess. It's a major pain to open this amp up. 15 screws to change a tube.
thats good info. I guess the only way to know is to take it apart and trace it out. Too bad H&K just couldn't be straight forward with me. They won't even answer my question of whether this amp needs higher voltage EL84's like an M. I can't even find out what the earlier versions came with stock. It's one of those mystery amps I guess.
Clemford,
A couple of minutes inside the amp with a multimeter will tell you what the voltages are etc.
jeff
A couple of minutes inside the amp with a multimeter will tell you what the voltages are etc.
jeff
Thank for those spec sheets. It's the 1rst one I've seen in English as I don't read Russian. I'm a newbe to tubes but it looks to me like they're 330v max so I might be safe with regular jj's in this amp.
Quote:
2. The SV83's screen grid (pin 9) is not able to accept an operating voltage of more than 200v DC. Because nearly all EL84 amps operate their screen grids at or near the plate voltage (in pentode, ultralinear or triode connection), the amplifier must be modified to provide a lower voltage to the SV83 screen grids. If triode connection is desired, the plate supply voltage must be limited to 200v DC.
Now I'm confused again, the spec sheet for the SV83 shows max Ug volts on pin 9 @ 300V yet the Svetlana bulletin says no more than 200V.
2. The SV83's screen grid (pin 9) is not able to accept an operating voltage of more than 200v DC. Because nearly all EL84 amps operate their screen grids at or near the plate voltage (in pentode, ultralinear or triode connection), the amplifier must be modified to provide a lower voltage to the SV83 screen grids. If triode connection is desired, the plate supply voltage must be limited to 200v DC.
Now I'm confused again, the spec sheet for the SV83 shows max Ug volts on pin 9 @ 300V yet the Svetlana bulletin says no more than 200V.
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Don't be confused, they're just trying to limit screen dissipation (1.5 Watts). That's what will kill the screens, not the voltage.
jeff
got a chance to check some voltages tonight. The amp does not have standby. It crackled scarily on a few of the pins. I had the meter set on just Volts.
pin 1(0V)
pin 2(15V)
pin 3(0V)
pin 4 (0V)
pin 5(0v)
pin 6(0V)
pin 7(402V)
pin 8(20V) and (0V) on the 2nd tube?
pin 9(399V)
pins 1&6 have no circuit connections and 6 & 3 are not connected to each other. Also, 3 connects to external components.
pin 1(0V)
pin 2(15V)
pin 3(0V)
pin 4 (0V)
pin 5(0v)
pin 6(0V)
pin 7(402V)
pin 8(20V) and (0V) on the 2nd tube?
pin 9(399V)
pins 1&6 have no circuit connections and 6 & 3 are not connected to each other. Also, 3 connects to external components.
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Pins 1 & 6 should be grounded.Check it thoroughly. On pin 2 you should read at least MINUS 15V, not plus 15. Can we have more détails about components connected to pin #3 ?
I only checked the volts on 1&6 so they might be grounded and it might be -15v. I attached a schematic that is supposedly the same circuit, just an older version amp.
Attachments
that attachment doesn't get larger like on my computer. I'm not sure what happened. It's a Hughes ans Kettner Tube 20 and the schematic is all over the web.
It's clear enough to see the basic circuit.
It would appear we have a discrepancy. The schem show the cathodes tired to ground?
jeff
It would appear we have a discrepancy. The schem show the cathodes tired to ground?
jeff