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Re: transformers [message #8744 is a reply to message #8742] Tue, 25 January 2005 21:24 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18793
Registered: January 2001
Illuminati (33rd Degree)
Hey Akhilesh,

You oughta get into the Guinevere project on the Group Build forum. I think you'd really enjoy it. Interested?

And by the way, Bill Wassilak announced he's having the next GPAC meeting at his house on the 5th. See you there?

Wayne

transformers [message #8746 is a reply to message #8743] Wed, 26 January 2005 02:18 Go to previous messageGo to next message
akhilesh is currently offline  akhilesh
Messages: 1275
Registered: May 2009
Illuminati (3rd Degree)
I agree John! trannies are important in all aspects of the tube circuit. I guess my point was (and of course its just my opinion) that the engineering demands on the output trannies of a directly coupled SET are much greater than, say, for the power tranny. This does not mean that a bad power tranny will do.

-akhilesh

transformers [message #8747 is a reply to message #8744] Wed, 26 January 2005 02:22 Go to previous messageGo to next message
akhilesh is currently offline  akhilesh
Messages: 1275
Registered: May 2009
Illuminati (3rd Degree)
HI Wayne, will check it out. Feb 5...i think we have some thing to go to between 3 & 5 pm, which I will try to get out of, since I really want to attend the GPAC meet.
-akhilesh

OPT Iron [message #8748 is a reply to message #8746] Wed, 26 January 2005 04:49 Go to previous messageGo to next message
PakProtector is currently offline  PakProtector
Messages: 935
Registered: May 2009
Illuminati (2nd Degree)
Hey-Hey!!!,
Sorry, I must disagree with the idea that a good OPT is only going to really benefit a DC SE amp. Not my experirience. I have found that PP requires the same sort of consideration. Even for measured paramenters like leakage L and capacitance. It is not just OPT's, other signal Iron is also very dependant on its construction details for excellent sound.

Good sound is easy. Four triodes, two or them low mu power valves like 2A3, a good OPT. With some careful design, and implementation, we can make the leap to excellent. We could just as easily start with EL34, 1619, 807 or 13E1...
regards,
Douglas

Re: OPT Iron [message #8749 is a reply to message #8748] Wed, 26 January 2005 05:56 Go to previous messageGo to next message
akhilesh is currently offline  akhilesh
Messages: 1275
Registered: May 2009
Illuminati (3rd Degree)
HI Doug,
I agree with you. I don't think anyone said that ONLY a DC SET will benefit from good iron....far from it.
However, the engineering requirements for the output tranny of a dc SET are significantly more demanding than for a parafeed SET, or a PP. Hence, the variation in quality is much more, and they also tend to be very costly.
what do you think?
-akhilesh


Why? [message #8750 is a reply to message #8749] Wed, 26 January 2005 06:07 Go to previous messageGo to next message
PakProtector is currently offline  PakProtector
Messages: 935
Registered: May 2009
Illuminati (2nd Degree)
what is it about a DC SET that is so much more demanding of the OPT compared to a PP amp?
regards,
Douglas

Re: Why? [message #8753 is a reply to message #8750] Wed, 26 January 2005 08:20 Go to previous messageGo to next message
akhilesh is currently offline  akhilesh
Messages: 1275
Registered: May 2009
Illuminati (3rd Degree)
HI Douglas,

IN the standard transformer coupling, single ended situation, the major disadvantage of the method is the average DC current that flows in the circuit must be supported by the transformer, making the transformer relatively large so that it does not saturate due to the DC only. This is probably the most common output coupling method, as it is relatively simple. At quiescent conditions, the power supply voltage appears on the plate (minus a little loss due to the IR loss in the transformer. During signal conditions, the output swings above and below the supply voltage.
akhilesh


Re: Why? [message #8754 is a reply to message #8753] Wed, 26 January 2005 08:48 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
Messages: 4973
Registered: May 2009
Illuminati (13th Degree)
Thanks for the Link AK; So in the parafeed you need to replace an expensive transformer with an expensive large choke; and in PP the mis-match unbalanced DC causes frequency imbalance; requireing much higher HT and therefor larger transformer.. Is that correct?
Thanks J.R.

Re: Why? [message #8756 is a reply to message #8754] Wed, 26 January 2005 09:28 Go to previous messageGo to next message
TubeCraft is currently offline  TubeCraft
Messages: 30
Registered: May 2009
Baron
"So in the parafeed you need to replace an expensive transformer with an expensive large choke.."

Don't forget it could be a simple resistor, or an itty-bitty CCS... (I like the sound of the resistor-loaded version best. Yeah, they'll both need more HT.)

TC


Re: Why? [message #8758 is a reply to message #8756] Wed, 26 January 2005 10:30 Go to previous messageGo to previous message
Manualblock is currently offline  Manualblock
Messages: 4973
Registered: May 2009
Illuminati (13th Degree)
Tube-craft; thanks for the reply. Let me ask; you really like the sound of the resistor loaded version better? I don't have the experience to be able to judge so I am relying on your reply. So; what does it do better?
I have heard the Bottlehead Paramours and think they sound pretty good except one thing I have always noticed listening to them with the Foreplay and Seduction ; and that is a certain grainy harsh sound on the mids that becomes more apparent on certain recordings. And a kind of brittle mettalic sound on certain instruments ie. cymbals and stringed instruments like violins. Since they are choke loaded para-feed I wondered what your experience is. I've always ascribed the sound to their use of SS rectifiers; so maybe thats wrong.
Thanks J.R.

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