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In Reply to: RE: I had a nice talk with Doc Hoyer. posted by Michael Samra on February 25, 2015 at 15:39:59
go ahead and reference to ground...sum the voltage changes across the outputs...you will get either zero or ~2x the input voltage...and since zero is obviously wrong...LOL
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
Follow Ups:
If its a 2 to 1 amplification,why bootstrap the driver? I will do it again with the measurement but you need to talk to Doc because he is very clear about this.
"If it measures good and sounds bad, it is bad; if it measures bad and sounds good, you have measured the wrong thing."
- Daniel R. von Recklinghausen
sounds good to me Mike, but go and see for yourself...:)
but try this thought experiment first:
apply a 1V signal to the grid of the finals( out of phase with each other of course)
measure this 1v to ground, and it will not matter if it is rms, or peak.
what do you expect the cathode response to be?
---I will expect to see ~.9v on the cathodes...this is approximately the cathode follower loss, right?
now, what do you see on the plate?
---I will tell you I expect to see the same, but opposite voltage on the plate as what I expect to see on the cathode.
as far as your 'why bootstrap' question goes, it is obviously needed since the output stage has a voltage gain less than 2.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
Gotcha!
"If it measures good and sounds bad, it is bad; if it measures bad and sounds good, you have measured the wrong thing."
- Daniel R. von Recklinghausen
Doc's favorite Peerless transformer is the one in W-6m Heath amps..
"If it measures good and sounds bad, it is bad; if it measures bad and sounds good, you have measured the wrong thing."
- Daniel R. von Recklinghausen
In the a-a load, it is arguably the best out there. Having two, I certainly parted with my Citation II in their favour. Those W6 are the only amps I have not running Class A.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
The Peerless on the W6M is part number 16431.The 16431 was chosen by Heath because it had a 70 volt secondary tap and hence would have some applications in the pro sound sectors of the marketplace.
Here's some historical trivia. Peerless designed two other outputs for the W6m amplifier.
I actually prefer each of these two alternates over the 16431. Neither of these two had the 70 volt line tap on the secondary.
One of the two had a bifilar wound secondary (16, 8, 4, & 1 ohm) and the other had a really cool trifilar secondary (again, 16, 8, 4, and 1 ohm).
If you don't need the 70 volt line tap then either one of the alternates would be a better choice IMO.
MSL
Builder of MagneQuest & Peerless transformers since 1989
Edits: 02/26/15 02/26/15 02/26/15
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