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Old 11th October 2002, 06:33 PM   #21
arnach is offline arnach  United States
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Default Bendix 6900

Yes, that is what I'm talking about.

Bendix, matched pair:

Used, tested 6900 $110
Used, tested 6900 gold pin 6900 $125
NOS, 6900 $160
NOS, 6900 gold pin pair $185

Is the NOS gold pin worth that much money?

Thanks,

Aaron
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Old 13th October 2002, 12:25 AM   #22
dice45 is offline dice45  Germany
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Aaron,
don't think so.
Any 6900 will blast you, sonically.
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Old 13th October 2002, 02:51 AM   #23
arnach is offline arnach  United States
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Default Alright

Sonically, 5AR4 or 5U4GB as the rectifier? I seem to find that 5U4 is directly heated, and 5AR is indirectly, isn't directly heated supposed to be sonically better? I can use either with the transformer..

Power supply is rectifier into 15H choke, 10uf cap into 10H choke, 200uf cap for the B+

Thanks,

Aaron
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Old 26th October 2002, 07:14 PM   #24
arnach is offline arnach  United States
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This week I took delivery of Sovtek 2A3 tubes :-)

Now I am ordering a Tango MX-175 power transformer, Tango LC-15-150 and Tango LC-10-200 chokes, and Tango NC-14 interstages.

Wish me the luck to carry out this project

Thanks to all! ultranalog, fdegrove, brett, dice45, and john! thanks again..

-- Aaron
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Old 26th October 2002, 11:57 PM   #25
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Hi,

Quote:
Thanks to all! ultranalog, fdegrove, brett, dice45, and john! thanks again..

In the name of all these people:break a Tango,err...a leg.

You're welcome
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Old 28th October 2002, 05:27 PM   #26
Joel is offline Joel  United States
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Default Re: Re: psu

Quote:
Originally posted by ultranalog

I try to avoid using same LC values in subsequent sections to avoid ringing and motorboating.
All you will accomplish by doing this is making a less effective filter.
Maximum filtering is obtained by using identical LC or RC stages, and basically any more than two isn't going to accomplish much (or enough to justify the expense), except put additional strain on your power transformer as it tries to keep all that capacitance charged up. The math to justify that statement can be found in the Radiotron manual.
Any ringing in this circuit would be caused by the transformers, and motorboating is a non issue with only a single voltage amplifier per stage.
You only get motorboating when three or more stages couple through a common supply.

I would remove everything after the second 100MF cap.
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Old 28th October 2002, 05:38 PM   #27
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Default Re: Re: Re: psu

Quote:
Originally posted by Joel
I would remove everything after the second 100MF cap.
What, like the circuit?
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Old 28th October 2002, 05:51 PM   #28
Joel is offline Joel  United States
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Default I detect a note of sarcasm...

Sorry, I should have been more clear.

To spite my "identical filters" statement above, I think this PS would do the job. 2nd choke is overkill, as is 300MF of cap.
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Old 28th October 2002, 06:25 PM   #29
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Default Re: I detect a note of sarcasm...

Just a bit, more tongue in cheek than anything. As you posted, after the second cap there is really only the circuit in the first PSU layout
Quote:
Originally posted by Joel
Sorry, I should have been more clear.

To spite my "identical filters" statement above, I think this PS would do the job. 2nd choke is overkill, as is 300MF of cap.
With a good shunt reg, I would say the second stage is unneccessary, but in an unregulated SE amp, the second LC stage would be of benefit sonically. I can hear the improvement in a good PP diff amp, so in a SE, which is about two orders of magnitude more sensitive to PSU irregularities I would expect it to be even more audible. Providing the capacitors are of good quality, and the PSU can charge them quickly enough, why would it be overkill?
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Old 28th October 2002, 06:31 PM   #30
Joel is offline Joel  United States
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Quote:
Originally posted by Brett
Providing the capacitors are of good quality, and the PSU can charge them quickly enough, why would it be overkill?
See my comment in my 71A post to fdegrove. This is a class A single ended amp - you don't need a reulated power supply. Yes, you would hear a difference (maybe) in a PP amp.

And, last time I checked chokes and big caps cost money ($100 for a 100MF Black Gate???, etc.) - so why spend the money if he doesn't have to? A very simple PS in this amp will be quite effective.
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