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Re: EZ81 in an AN DAC

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Jim McShane

(D)

In Reply to: EZ81 in an AN DAC posted by steven oda on January 18, 2004 at 18:00:53:

Steve,
Will a 6V4 work? It's pin compatible with a 6CA4. And it only draws .6 amps heater current. Check out the specs and see if it'll do.

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how about... - steven oda 08:21:18 01/19/04 (6)
Jim,
Separate tranny for a 5Y3GT? Or that wonderful Bendix 6016?
- Re: how about... - Jim McShane 08:30:56 01/19/04 (5)
  Hi Steve!
  You could do that, it depends how ambitious you are!
  But the 6V4/EZ80 will certainly provide the current if the original circuit uses a 6X4/EZ90. It's indirectly heated too, for slow warm up, and it allows it to share the heater supply just like the 6X4.
  That would probably be the simplest way anyhow... How much current do you need for that DAC?
  - Re: how about... - steven oda 08:55:31 01/19/04 (4)
    Jim,
    Probably, max at 100mA per channel. But, the pi-filter stage and chokes are really over-engineered. So, why not beef up the rectifier?
    Just a fleeting thought.
    - Re: how about... - Jim McShane 09:04:08 01/19/04 (3)
      Hmm, at 100 ma./channel the 6V4 is overmatched. Actually, even a 5Y3 is close to the limit (125 ma. in the GE book). The 6CA4 actually has a higher current limit at 150 ma (again using the GE book). But to supply 200 ma. you'd need multiple tubes.
      That DAC really needs that much? Wow, you really are in 5U4/5AR4 country if you use a single rectifier. Or you'll need multiple tubes...
      - Re: how about... - steven oda 09:09:03 01/19/04 (2)
        
        In Reply to: Re: how about... posted by Jim McShane on January 19, 2004 at 09:04:08:
        
        Jim,
        I'm saying 100mA absolute max current demand on the greatest bass transient probably known to mankind :-)
        20-40mA RMS is probably more reasonable.
        
        Re: how about... - Jim McShane 10:22:25 01/19/04 (1)
        
        In Reply to: Re: how about... posted by steven oda on January 19, 2004 at 09:09:03:
        
        Then I'd go EZ80/6V4.
        
        Re: how about... - ShiFtY1000 21:11:08 01/19/04 (0)
        
        In Reply to: Re: how about... posted by Jim McShane on January 19, 2004 at 10:22:25:
        
        I've scavenged many used Mullard EZ80s from old gear, they all still test excellent. Also some ratings according to my 1956 Mullard valve manual are:
        Filament: 6.3V/600mA
        Max heater/cathode voltage: 500V
        Max input voltage 350V per anode
        Max output current 90mA
        Max current per anode (peak) 270mA
        Max input capacitor 50uF
        Hope this helps. It is a much gruntier tube than the 6X4...

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