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Re: 45 parafeed SET vs. 845 transformer-coupled PP

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Doc B.

(i)

In Reply to: 45 parafeed SET vs. 845 transformer-coupled PP posted by Kurt Strain on June 11, 2000 at 12:53:37:

Hey Kurt, you might want to try the 845 in a parafeed SE circuit similar to the 45 circuit. Tucker and I scabbed one together a few years back, running at relatively low voltages, I think we had maybe a 900V supply and we ran direct coupled with a CCS'd 5965 driver, so the 845 probably saw about 600V p-k. I'd guess we got maybe 5 watts out. It was interesting how much it sounded like the 45, obviously louder and with some more bass punch, but it had similar resolution and that same black background.

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Re: 45 parafeed SET vs. 845 transformer-coupled PP Kurt Strain 12:51:37 06/14/00 (1)
Thanks for the suggestion. I'm mulling this one over. This is not a bad idea. I could use the Peerless S-275 as an 8K primary parafeed OPT and use a 50H choke. I'll probably need a choke or interstage for the driver since CCS'ing from HV looks unreliable right now. Is it worth the money to try it and probably still stay with the 45? Hmmm... If it didn't cost me anything I would try it.

Kurt
- Re: 45 parafeed SET vs. 845 transformer-coupled PP Doc B. 19:37:21 06/14/00 (0)
  Well, our lowly 900V power supply forced us to run the direct coupled 845 at a low Vp and therefore we didn't need too much driver swing. We used the arrangement I published for a 45 SE parafeed back in '97, where we feed the top of the CCS from the cathode of the output tube, so the CCS only saw 300V at the input. Of course wity this arrangement you probably get a bit less swing from the driver stage than the grid of the output tube needs to hit 0V, but it seems a decent compromise if power output isn't the number one priority, and you get some protection from B+ overvoltage on startup stressing the CCS.
  I guess I'd say that it's an interesting experiment if you have the parts sitting around, which we did, but if you are happy with a 45's power, I don't suspect you will hear any thing that much better, besides just more loud. And of course an 845 demands some hum reduction work because of the 10V filament.
Re: 45 parafeed SET vs. 845 transformer-coupled PP drummerwill 21:49:06 06/13/00 (0)
There you go Kurt, I seconded Doc B's motion,
low power SE parafeed!
Willie

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