I know that the parafeed configuration calls for special requirements regarding the construction of the output transformers used in eg. a linestage. What about the ultrapath configuration. Can I use the same transformers as I would have done in a "standard" configuration? (We are talking linestage here.)
You can use any transformers for ultrapath. Gapped or Parafeed doesn't matter.What about the ultrapath configuration.
Bas Horneman said:You can use any transformers for ultrapath. Gapped or Parafeed doesn't matter.
No, you can't use parafeed transformers. There is DC on them.
My understanding is that "Parafeed" transformers are not designed to have DC current across their primary.No, you can't use parafeed transformers. There is DC on them.
There should be no issue using them in an ultrapath circuit, because the cap on the cathode leg of the transformer blocks DC current from plate to cathode.
Since there is no DC current, transformers with less air gap and a smaller cores can be used.
Regards;
Doug
I have not tried parafeed myself and this is something I'd like to explore. I have a spud amp made of a single 417A which is wired normally. As I am having small OPTs made, I am hoping of getting better performance if I wire the amp in parafeed.
So the next question is, what sort of capacitor one should use for parafeed? I understand it has to be relatively high in value, i.e., 5uF or something and must be non-polar. Is this really the case?
So the next question is, what sort of capacitor one should use for parafeed? I understand it has to be relatively high in value, i.e., 5uF or something and must be non-polar. Is this really the case?
DougL said:
My understanding is that "Parafeed" transformers are not designed to have DC current across their primary.
There should be no issue using them in an ultrapath circuit, because the cap on the cathode leg of the transformer blocks DC current from plate to cathode.
Since there is no DC current, transformers with less air gap and a smaller cores can be used.
No, you are wrong. The ultrapath is a single feed design.
Here's the schematic
shamelessly taken from http://www.nutshellhifi.com/library/ETF.html
If there is no DC through the transformer, then there is no DC through the tube either.
There is aparently a bit of black magic involved, but that magic depends on the plate load. If you use a choke load, then there is some math you can do, but with a CCS it is little more guess work. But, 5uF is usually a good starting point (Here's where I asked the same question, I am drsx over there): http://www.audioasylum.com/forums/magnequest/messages/5502.htmlarnoldc said:So the next question is, what sort of capacitor one should use for parafeed? I understand it has to be relatively high in value, i.e., 5uF or something and must be non-polar. Is this really the case?
Agreed.No, you are wrong. The ultrapath is a single feed design
I confused it with what Lynn is calling the Western Electric (output), which does not have DC current.
http://www.nutshellhifi.com/library/Pix-D.gif
Regards
Doug
A parafeed transformer always needs a dc blocking cap. But I don't see why you could not use ultrapath as well. Ultrapath is from b+ to cathode as in Jeff Lessard's Horus.
http://www.magnequest.com/diy/lessard/diy_lessard_schematic.htm
http://www.magnequest.com/diy/lessard/diy_lessard_schematic.htm
Thanks for the link. It was a good read.There is aparently a bit of black magic involved, but that magic depends on the plate load. If you use a choke load, then there is some math you can do, but with a CCS it is little more guess work. But, 5uF is usually a good starting point (Here's where I asked the same question, I am drsx over there): http://www.audioasylum.com/forums/m...sages/5502.html
One should not use ultrapath with (classic) parafeed. The ever-informative P Joppa explains why here (although he is referring to the Paramour, same applies to any SE parafeed arrangement):
Link to parafeed with ultrapath post
Hope this helps
Raymond
Link to parafeed with ultrapath post
Hope this helps
Raymond
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