Quad II - Forty

rossdt · 18th November 2006, 11:57 AM

Is there someone that it can send me the schematic of Quad II - Forty?
Thank you in advance.

Alessandro

GEORGIEV · 21st November 2006, 03:50 PM

analog_sa · 21st November 2006, 07:29 PM

Thanks G-n Georgiev

No surprise it sounds worse than the original.

GEORGIEV · 22nd November 2006, 09:02 AM

Dear Mr. Alessandro,
I haven't Quad II - Forty scheme. This scheme is the same Quad II mono amplifier (KT66) 1949-1970. I have followed and checked the voltages in this scheme and montage. I have to tell you that Quad II - Forty has higher anode voltage than Quad II mono amp anode voltage.

Regards, Georgi Georgiev, Bulgaria

rossdt · 24th November 2006, 10:58 PM

Thank you very much!
What is the black component under the rectifier?
Thanks

Alessandro

coolmaster · 25th November 2006, 05:27 AM

Most likely a NTC thermistor for cheap protection and limit current inrush.
Bright idea! just in case the rectifier tube goes kaput, saving further damage to amplifier.

stokessd · 26th November 2006, 02:00 PM

Please tell me that amplifier didn't cost very much money.

I've got the original quad II schematic here:

http://quadesl.com/refurb/refurb_quadTube.html

Sheldon

Johan Potgieter · 30th November 2006, 11:26 PM

Quote:

Originally posted by rossdt
Thank you very much!
What is the black component under the rectifier?
Thanks

Alessandro

It is a very low value thermister in series with the rectifier (5U4) filament to give a kind of slow power-up.

The Quad II-40 circuit is essentially the same as the Quad II, with some slightly different value resistors to accomodate the 6SH7 drivers. The other difference is the separate cathode resistors (bypassed) for the KT88 power tubes.

Regards

18th November 2006, 11:57 AM	#1
rossdt diyAudio Member Join Date: Jul 2006	Quad II - Forty Is there someone that it can send me the schematic of Quad II - Forty? Thank you in advance. Alessandro

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21st November 2006, 03:50 PM	#2
GEORGIEV diyAudio Member Join Date: Feb 2005 Location: sofia

21st November 2006, 07:29 PM	#3
analog_sa diyAudio Member Join Date: Aug 2002 Location: Sofia	Thanks G-n Georgiev No surprise it sounds worse than the original.

22nd November 2006, 09:02 AM	#4
GEORGIEV diyAudio Member Join Date: Feb 2005 Location: sofia	Dear Mr. Alessandro, I haven't Quad II - Forty scheme. This scheme is the same Quad II mono amplifier (KT66) 1949-1970. I have followed and checked the voltages in this scheme and montage. I have to tell you that Quad II - Forty has higher anode voltage than Quad II mono amp anode voltage. Regards, Georgi Georgiev, Bulgaria

24th November 2006, 10:58 PM	#5
rossdt diyAudio Member Join Date: Jul 2006	Thank you very much! What is the black component under the rectifier? Thanks Alessandro

25th November 2006, 05:27 AM	#6
coolmaster diyAudio Member Join Date: Jul 2005 Location: MY	Most likely a NTC thermistor for cheap protection and limit current inrush. Bright idea! just in case the rectifier tube goes kaput, saving further damage to amplifier.

26th November 2006, 02:00 PM	#7
stokessd diyAudio Member Join Date: Nov 2002 Location: Fort Wayne, IN	Please tell me that amplifier didn't cost very much money. I've got the original quad II schematic here: http://quadesl.com/refurb/refurb_quadTube.html Sheldon

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