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Old 15th October 2004, 04:35 PM   #1
dubh is offline dubh  Australia
diyAudio Member
Join Date: Oct 2004
Question Cyrus PSX-R copy

I have a DVD7 Cd/DVD player. Delighted by the detailed sound, interested in PSX-R to take over power supply to motor, claimed by many to improve sound. However, I am very reluctant to pay 400 pounds for what I need of the PSX-R: - one +-21V regulated power supply. Connection between Cyrus component and PSX-R is by 5 pin XLR male socket. Top pin is +5V relative to all pins. Centre 3 pins look to be +-21V, earth, +-21V - polarity unknown.

Does anybody have schematic of PSX-R circuit or details of pin values/functions in connection from PSX-R, any info on PSX-R welcome.

Cheers, dubh
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Old 15th October 2004, 06:25 PM   #2
AndrewT is offline AndrewT  Scotland
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Join Date: Jul 2004
Location: Scottish Borders
Hi, both outputs of the PSXr are not fixed.
Reading the manual & advertising I believe the plus & minus 30volt outputs are the high current to feed say a power amp.
The low current outputs are somehow adjustable. I guess the 5v lead is fed into some load & PSXr detects either a current flow or a voltage feedback & uses this to determine the setting for the output voltage. This is used for low level stages and/or to drive digital controls. I think the literature refers to a maximum of plus & minus 21v. Have they overcome the need for a ground reference? I note that cyrus 8 uses the +-30v to drive the preamp and the internal tx drives the power amp. Clever, avoids hi I through the XLR and keeps the higher voltages for the 70w output circuit on board.
These dammed SMD circuits!
regards Andrew T.
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Old 18th October 2004, 09:28 AM   #3
dubh is offline dubh  Australia
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Join Date: Oct 2004
Hi Andrew
From my reading of the Cyrus documention, there are 3 possible outputs as follows:

Outputs 35.5 VDC for stereo power and integrated amplifiers
18-30 VDC for monobloc power and other amplifiers
21 VDC for low power applications
Load regulation 35.5V 0.2% full power when connected to a Cyrus Integrated amplifier
Load regulation 21V 0.001% @ 20VA
Line regulation 0.2% at full output load
Noise <40V rms

From my examination of the DVD7 circuit board, the centre 3 contacts appear to be +ve, earth, -ve, order uncertain.

From the Cyrus website FAQ, the decision to power the Cyrus 8 preamp was taken on the basis of sound during testing.

I agree, the SMD circuits make life hard. The only way around this is for some PSX-R owner to apply 5V to the uppermost socket in the connection lead, and to then test the voltage on pin 2 and 4 relative to pin 3 (counting downwards from the top). The role of pin 5, if any, would be worth exploring also.

The only possible motivation for a proud PSX-R to muck about with their PSX-R like this, is that perhaps it might save them buying another PSX-R. Any takers?
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Old 7th February 2007, 04:59 PM   #4
AndrewT is offline AndrewT  Scotland
diyAudio Member
Join Date: Jul 2004
Location: Scottish Borders
has anyone tried an unregulated PSX style power supply into the modern amps that would normally take PSXr?

I am thinking that a PSX clone using two independant supplies outboard and feeding these to the existing power stages might reap some reward. Keep the on board capacitors as high value local decoupling.

Any thoughts?

two regulated dual polarity supplies feeding the power stages, but again keeping the on board capacitors as local decoupling.

All the Cyrus 8s are out of warranty and must be aching for experimentation.
regards Andrew T.
Sent from my desktop computer using a keyboard
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