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    Building, troubleshooting and testing of these amplifiers should only be
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Anthem Integrated 1

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Tube_Dude

Tube_Dude

Member
Joined 2002
Dear Guys

A friend of mine bring to me a Anthem Integrated 1 , to put some new tubes.

The strange thing is, the power transformer model Hamond H300211, have for the B+ a output of 355 Volts AC, that gives ~ 460 Volts DC.

To much for EL84, I'm afraid.

The hypotheses of primary error connection is not valid ,. because all the others voltages are correct:
-17,4 Volts AC for the negative bias voltage.
-11,7 Volts AC
-6,3 Volts AC for the tube heaters.

It seems to me that someone put in a transformer for a EL34 amp , as the rail voltage after rectification is around 460 Volts.

In a nutshell , I would be glad if anyone here can tell me , if the correct secundary voltage is effectively 355 Volts Ac or if that value is definitively wrong .

Thanks in advance for your help.

Cheers
 
Tube_Dude

Tube_Dude

Member
Joined 2002
kevinkr said:
Try contacting the folks at http://www.partsconnexion.com/ as most of the principle people from SF are now involved with this outfit and should be able to help you with your question.
Click to expand...

Thanks Kevin

I have already send a mail to Chris at "Partsconnexion" , following an advice from a guy in Audiokarma.

But till now, I don't have any answer.

From SF , they said that the voltages are correct , but i don't think so... ;)

Regards
 
kevinkr

kevinkr

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Might be that the original design used a more rugged version of the EL84 - something like the Russian 6P14P-EB or EV?

460V does seem rather high to me too.. I have an ancient Realistic Amplifier which uses voltages in the range of 410V which I have had to pad down to slightly under 400V. The Japanese tubes in this amplifier seemed able to take the abuse, as did the Philips ones I installed in my Dad's amp 30+ yrs ago, this one, recently acquired has 6P14P in it now after the JJ 6BQ5 I bought for it super novaed. :hot:

I am not familiar with the Anthem, is it possible that it drops some substantial voltage across resistors or chokes in the power supply? Operating currents may be as high as 200mA combined for both amplifier channels depending on operating point chosen. (The old Realistic amplifier uses very close to 50mA per tube including the screens.)

HH Scott ran 7189A in the 299B at rather high voltages, well over 400V IIRC, and fairly high dissipations as well..
 
kevinkr

kevinkr

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Joined 2004
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Paid Member
Tube_Dude said:


To me too, Kevin

And another "strange " thing , the bias negative supply have a 17volts zenner that has been changed for a 3,3k resistor , for a negative bias voltage of near 23 negatives volts.


The valves that it was using are JJ EL84.
Click to expand...

That actually makes sense for the plate voltage being used, still that is way outside of the realm any 6BQ5 could be expected to survive long term. Zener regulation on the bias is not a good idea unless at least the screen voltage is regulated too. I would think the 6P14P would be a better choice than the EL84/6BQ5, and I think there might be another Russian one reputedly even better if you search here for it.
 
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