|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
97.95.43.235
In Reply to: RE: DO NOT DO THIS ON MAC AMPS ! posted by Lee of Omaha on July 03, 2016 at 18:58:19
Lee
I guess I misunderstood because when we do a full wave bridge on a Cit 2 bias,we end up using a torroid with dual secondaries that we series connect and then use a 4 diode bridge.
To be honest,doublers in the Mac and Cit 2 amps regulate very well by virtue of their low resistance secondary windings especially when you use it with the new doubler caps they have today.If you use the 820uf panasonic or Nichicon 105 degree caps along with a good buss bar and an added hash filter,you aren't going to do any better than that for filtering.I suppose there are other ways to do it,but Jim McShane has tried many different setups before he came up with the one for the Citations and we just implemented with the Macs because the power supplies mirrored each other. The added decoupling also helps with stability.I don't know if you have seen some of my posts but I have always put up the end results with measurements and waveforms and that kind of gives you an idea of where you are at..You can try a different way if you keep the same taps..I thought you were using a different bias transformer and with the Macs you can't if you want it to track correctly.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
Edits: 07/03/16Follow Ups:
Ah, we are on the same page.
I don't think "regulate" is the word you're after in "...doublers in the Mac and Cit 2 amps regulate very well..." since the voltage will still scale with line voltage. I recognize the quality added by low resistance windings.
I was speaking hypothetically when I said regulate but what I really mean is stability..Today's Mac tube amps like the reissue Mc275 doesn't use any form of regulation that we use in conventional circuitry.It essentially mirrors the original circuit. The reason behind that I would assume is the fact that the unity coupled circuit doesn't operate independently of the other elements in the circuit.It moves proportionally up or down with signal. In a conventional pentode connected output circuit, we can regulate G2 without regulating the plate voltage.
I am curious tho. I would love to see what would happen in a Mac amp if we did regulate the plate and or G2 just to see what would happen to operating conditions.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
I think you'd be ok if you regulated B+ AND C-, but not just one. Since G2 and the plates are connected, if you regulate one of them I think you'd drastic change the operation of the amp.
I believe you are right.I may give it a try as well.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: