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Old 11th April 2005, 02:26 PM   #641
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Hi Protos,

I will try some reference zeners (6,2V) wich can be bought with very low temperature coefficients. Like LM329 or1N825A @ 0,002%/°C. A normal zener has 0,04 to 0,08 %/°C

Resistors (1%) generally have a quite low temperature coefficient. I bought some 390 Ohms 0,1% with TK25 ppm so these wonīt be the problem.

William
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Old 11th April 2005, 04:09 PM   #642
protos is offline protos  Greece
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I think I have some lm 329 lying around for another project.They were not that easy to find if I remember even RS didnīt stock them in Ireland.
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Old 15th April 2005, 02:10 PM   #643
protos is offline protos  Greece
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I tried running the amps with single ended input.However with the neg input tied to ground the feedback network from the output starts messing up the relative offset values which start to track the absolute offset values.This means that at start up you can get quite a few volts of rel dc on the output plus it is drifting all over the place.
I canīt think how you can run them single ended without a rel offset problem.
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Old 15th April 2005, 03:14 PM   #644
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Protos,

tie the negative input to ground via a cap. Mine runs fine this way.

William
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Old 15th April 2005, 04:02 PM   #645
protos is offline protos  Greece
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Well I did that but it did not seem to work.But I realize now that I did it wrongly.Because I have only balanced chassis connectors I was using se-bal adaptors which short the neg to ground at the input on the case..I put the cap between the connectors neg input at the case to the neg input on the board which I realize now is useless.I should have put it on the ground connector.Just goes to show what silly things one can come up with early in the morning without putting the brain into gear.
Shhh - donīt mention this to anybody - my credibility will be shot to pieces
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Old 15th April 2005, 05:23 PM   #646
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I wonīt say a thing

William
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Old 20th April 2005, 12:01 PM   #647
Jozua is offline Jozua  South Africa
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Hi

I know there has been a group buy some time back and I am wondering if there are any people who have dropped out of the project and would be willing to consider selling their boards ?

I am am looking for 4 boards, preferably of the the latest version that was made.


Please e-mail me via the group or privately at hugot@icon.co.za

Thanks

Jozua
Cape Town
South Africa
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Old 20th April 2005, 01:00 PM   #648
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I have 6 of the HiFi Zen/Grataku boards, two of which may well be going to SA to someone else. If you're interested, drop me a line. It might well make postage cheaper if they go in one package, to be split when they get there.
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Old 21st April 2005, 02:04 AM   #649
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Folks, I have a question please..

I am building a 'universal power supply' with a very large transformer to run a couple of Aleph X mono blocks as well as some more small Pass type amps. These amp chassis' are separate from the psu and will use an umbilical cord. My intention is to use a 3 wire cord containing +, gnd, and -.

My question: Does anyone have a problem with the seperate amp chassis' not being at earth, but at audio ground? There will ne no mains in or near them...

Would it be better to avoid earth in the amps also to reduce possible gnd loops?

Thanks,
Marc
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Old 21st April 2005, 02:42 AM   #650
Coulomb is offline Coulomb  England
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Quote:
Originally posted by mpmarino
Folks, I have a question please..

I am building a 'universal power supply' with a very large transformer to run a couple of Aleph X mono blocks as well as some more small Pass type amps. These amp chassis' are separate from the psu and will use an umbilical cord. My intention is to use a 3 wire cord containing +, gnd, and -.

My question: Does anyone have a problem with the seperate amp chassis' not being at earth, but at audio ground? There will ne no mains in or near them...

Would it be better to avoid earth in the amps also to reduce possible gnd loops?

Thanks,
Marc
Well having the chassis at earth ground is better for isolating noise for the Audio circuits. Keep the "Audio" ground off the chassis or on is a matter of ground loops. If it was an all in one chassis it would take extroadinary measures to keep them seperate in most applications. I find it difficult just to implement the Thermistor or bridge between the chassis and ground as the IEC Power filters I use ground as soon as you screw them to the chassis.

If one of your HV DC leads comes loose and touches the chassis it might be just as dangerous as an AC lead. If the Chassis is grounded at least it would trip a breaker.

Regards

Anthony
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