PA-060 use

gtmcgar1 · 22nd May 2006, 08:29 PM

Looking for a stereo circuit recommendation where I can use a spare MQ power transformer (pa-060) 720vct/300mA, 55v bias, 2x 6.3v@5A, 5V @4A. Not too bothered about power output but I do have a restriction on chassis size, its ~10x14. Thanks

ethermion · 22nd May 2006, 08:41 PM

It was intended to be a clone of a Dynaco ST-70 power transformer. 2x35W PP EL34. If you read up on the ST70, you will also find tons of variations you could implement.

http://www.triodeelectronics.com/mq060.html

http://www.curcioaudio.com/st7_mnl.pdf

Have fun,
-e

Eli Duttman · 22nd May 2006, 10:43 PM

gtmcgar1,

What is your preamp situation? If you don't have a preamp, consideration should be given to constructing an "integrated" amp.

Your power trafo lends itself to construction of a PP stereoblock. If the idea of an "integrated" amp is appealing, a 12AT7 differential splitter/driver feeding a PP pair of 7591s will reach full power directly driven by a CDP.

gtmcgar1 · 23rd May 2006, 05:36 PM

Thanks for the replies. I should clarify my post, sorry. The PT is left over from an st70 rebuild, its new so I wanted to put it to use to make another (non st70) amp. I have a stereo chassis available also. With the integrated amp suggestion I'm thinking maybe I should do a preamp linestage or an integrated since I already have a pair of 300b monos. If you have a schematic for the 7591 integrated or any other suggestions for a line stage that will work with this PT please post the schematic. Thanks Gordon

Eli Duttman · 24th May 2006, 01:34 AM

Gordon,

Look here. It's a fairly recent thread that addresses many of your questions.

You don't have to get involved with the fancy O/P "iron" John did. Owning 300B monoblocks implies reasonably efficient speakers. You will do fine either triode or ultralinear wired.

I've given some thought to using your power trafo in a PP 7591 "integrated" stereoblock. You will need 2 chokes, but no additional power trafo is required.

B+ rectification will be done by a pair of 6AU4 damper diodes. A CLC filter will be employed.

The B- supply will be derived from the 5 VAC winding via a voltage multiplier made from "noiseless" Schottky diodes. The O/P of the multiplier will feed a Hammond 154E 20 H./20 mA. choke followed by additional capacitance. Ripple will be nice and low.

Each of the 6.3 VAC windings will energize a 6AU4, a 12AT7, and a pair of 7591s. Please observe that the total draw is well under the max. allowed.

BTW, take some time and read the "El Cheapo" saga. The 12AT7 splitter/driver was 1st worked out there.

22nd May 2006, 08:29 PM	#1
gtmcgar1 diyAudio Member Join Date: Feb 2005 Location: u.s.a	PA-060 use Looking for a stereo circuit recommendation where I can use a spare MQ power transformer (pa-060) 720vct/300mA, 55v bias, 2x 6.3v@5A, 5V @4A. Not too bothered about power output but I do have a restriction on chassis size, its ~10x14. Thanks __________________ wig

22nd May 2006, 10:43 PM	#3
Eli Duttman diyAudio Member Join Date: Apr 2004 Location: Plainsboro, NJ	gtmcgar1, What is your preamp situation? If you don't have a preamp, consideration should be given to constructing an "integrated" amp. Your power trafo lends itself to construction of a PP stereoblock. If the idea of an "integrated" amp is appealing, a 12AT7 differential splitter/driver feeding a PP pair of 7591s will reach full power directly driven by a CDP. __________________ Eli D.

23rd May 2006, 05:36 PM	#4
gtmcgar1 diyAudio Member Join Date: Feb 2005 Location: u.s.a	Thanks for the replies. I should clarify my post, sorry. The PT is left over from an st70 rebuild, its new so I wanted to put it to use to make another (non st70) amp. I have a stereo chassis available also. With the integrated amp suggestion I'm thinking maybe I should do a preamp linestage or an integrated since I already have a pair of 300b monos. If you have a schematic for the 7591 integrated or any other suggestions for a line stage that will work with this PT please post the schematic. Thanks Gordon __________________ wig

24th May 2006, 01:34 AM	#5
Eli Duttman diyAudio Member Join Date: Apr 2004 Location: Plainsboro, NJ	Gordon, Look here. It's a fairly recent thread that addresses many of your questions. You don't have to get involved with the fancy O/P "iron" John did. Owning 300B monoblocks implies reasonably efficient speakers. You will do fine either triode or ultralinear wired. I've given some thought to using your power trafo in a PP 7591 "integrated" stereoblock. You will need 2 chokes, but no additional power trafo is required. B+ rectification will be done by a pair of 6AU4 damper diodes. A CLC filter will be employed. The B- supply will be derived from the 5 VAC winding via a voltage multiplier made from "noiseless" Schottky diodes. The O/P of the multiplier will feed a Hammond 154E 20 H./20 mA. choke followed by additional capacitance. Ripple will be nice and low. Each of the 6.3 VAC windings will energize a 6AU4, a 12AT7, and a pair of 7591s. Please observe that the total draw is well under the max. allowed. BTW, take some time and read the "El Cheapo" saga. The 12AT7 splitter/driver was 1st worked out there. __________________ Eli D.

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22nd May 2006, 08:41 PM	#2
ethermion diyAudio Member Join Date: Apr 2005 Location: ffx station, va	It was intended to be a clone of a Dynaco ST-70 power transformer. 2x35W PP EL34. If you read up on the ST70, you will also find tons of variations you could implement. http://www.triodeelectronics.com/mq060.html http://www.curcioaudio.com/st7_mnl.pdf Have fun, -e

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