More junk from China

Original Burnedfingers · 21st February 2011, 12:00 PM

Why the 6SN7 attached to the power supply?

commstech · 21st February 2011, 12:23 PM

Quote:

Originally Posted by 6BG6GA

Why the 6SN7 attached to the power supply?

why even bother with something u see as junk?

limono · 21st February 2011, 01:06 PM

Complex of a citizen of once industrial country

Ty_Bower · 21st February 2011, 01:40 PM

Quote:

Originally Posted by 6BG6GA

Why the 6SN7 attached to the power supply?

Maybe some kind of current regulator... though wouldn't a pentode be the usual choice?

kavermei · 21st February 2011, 01:54 PM

Also, 300V half-wave rectified cannot possibly feed a 330V zener regulator

Palustris · 21st February 2011, 02:21 PM

It's a mini regulator. Bogen used the same thing for their screen regulators on some amps. The SRRP suffers from poor power supply ripple rejection so it could be a useful application of the regulator.

Bigun · 21st February 2011, 02:29 PM

Looks like a kind of active bootstrap current source - it takes a signal from the cathode of the lower tube and since the cathode resistor is not bypassed it samples the signal.

DF96 · 21st February 2011, 05:29 PM

My guess is a bootstrap voltage source, in order to reduce distortion? It won't improve PSRR, but probably make it worse by directly injecting HT noise into the input cathode.

300V RMS AC half-wave rectified gives 420V, so plenty to drive a 330V zener chain.

smoking-amp · 21st February 2011, 11:30 PM

Odd! It does seem the lower 6SN7 is driving the upper one. But it's the opposite phase of a typical voltage bootstrap. It lowers the plate voltage on the middle 6SN7 plate when the signal is rising toward +. Since the effect would be small: 1/Mu, thru the plate, I can only guess this is some scheme for affecting distortion. Notice the same size cathode resistors on the lower two 6SN7's. Simulation needed. Could maybe replace the topmost 6SN7 with a Mosfet for convenience.

rs7cai · 22nd February 2011, 07:23 AM

Quote:

Originally Posted by 6BG6GA

Why the 6SN7 attached to the power supply?

You really do not understand this circuit......

21st February 2011, 01:54 PM	#5
kavermei diyAudio Member Join Date: Jan 2005 Location: Lokeren, Belgium	Also, 300V half-wave rectified cannot possibly feed a 330V zener regulator __________________ Never send a human to do a machine's job. --Agent Smith

21st February 2011, 02:29 PM	#7
Bigun diyAudio Member Join Date: Jan 2009 Location: K-W Ontario Blog Entries: 2	Looks like a kind of active bootstrap current source - it takes a signal from the cathode of the lower tube and since the cathode resistor is not bypassed it samples the signal. __________________ "The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.

21st February 2011, 11:30 PM	#9
smoking-amp diyAudio Member Join Date: Dec 2001 Location: Hickory, NC	Odd! It does seem the lower 6SN7 is driving the upper one. But it's the opposite phase of a typical voltage bootstrap. It lowers the plate voltage on the middle 6SN7 plate when the signal is rising toward +. Since the effect would be small: 1/Mu, thru the plate, I can only guess this is some scheme for affecting distortion. Notice the same size cathode resistors on the lower two 6SN7's. Simulation needed. Could maybe replace the topmost 6SN7 with a Mosfet for convenience. __________________ Ohms Law V = I R

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21st February 2011, 01:06 PM	#3
limono diyAudio Member Join Date: Mar 2007	Complex of a citizen of once industrial country

21st February 2011, 02:21 PM	#6
Palustris diyAudio Member Join Date: Aug 2006 Location: Cape Cod	It's a mini regulator. Bogen used the same thing for their screen regulators on some amps. The SRRP suffers from poor power supply ripple rejection so it could be a useful application of the regulator.

21st February 2011, 05:29 PM	#8
DF96 diyAudio Member Join Date: May 2007	My guess is a bootstrap voltage source, in order to reduce distortion? It won't improve PSRR, but probably make it worse by directly injecting HT noise into the input cathode. 300V RMS AC half-wave rectified gives 420V, so plenty to drive a 330V zener chain.

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