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Old 11th October 2006, 09:08 AM   #3991
jksmurf is offline jksmurf  Hong Kong
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Quote:
Originally posted by 6h5c
..... I want to do a comparison between the players I have, and in one of them I want to bias the opamps in class-A. But if you want to try it yourself, it's a 5 minute mod. Just solder a resistor between each output and the negative voltage rail. Somewhere between 3k3 and 3k9 for +/-12V supply. That should give you a pretty good idea of the change in sound. If you like it you can change the resistor into a more sophisticated FET current sink.
Regards, Ray
Quote:
Originally posted by SimontY
It may be important to add power supply decoupling right under the pins (of the socket - use a socket so you can compare op-amps easily). I use Panasonic FC 33uF/50v and they work well. These go from + to earth and - to earth. I think + and - are pins 4 and 8 on the op-amps. Simon
OK, so there's (i) "biasing the opamps in class-A" and (ii) "power supply decoupling" ... how many have done (i), (ii) or both and what are your experiences?

Cheers

k.
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Old 11th October 2006, 09:35 AM   #3992
SimontY is offline SimontY  United Kingdom
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Quote:
Originally posted by jksmurf
OK, so there's (i) "biasing the opamps in class-A" and (ii) "power supply decoupling" ... how many have done (i), (ii) or both and what are your experiences?

Cheers

k.
Not biased any opamps into class a. Mainly becuase many people have said it's not worth it/doesn't get better.

I have listened before and after psu bypassing done under the op-amp socket legs. Listening to the op-amp both ways (OPA2134) the difference was very useful extra control and involvement. The sound got tighter. This was using small, low impedance electrolytics.

I don't doubt the improvements will be greater or lesser depending on the quality of the caps used to bypass, the other caps used, their proximity to the op-amps and also the type of op-amp. Search for posts by the user CarlosFM (I think that's the one) as he's tested many capacitor and op-amp combinations.

Regards,
Simon
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Old 11th October 2006, 10:35 AM   #3993
Robfow is offline Robfow  Singapore
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Thank you SimontY. I will now wait for my LM4562 to arrive
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Old 11th October 2006, 11:27 AM   #3994
poynton is offline poynton  United Kingdom
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Quote:
Originally posted by SimontY


Not biased any opamps into class a. Mainly becuase many people have said it's not worth it/doesn't get better.


Hi.

The reviews I have read state that biasing into class A makes a subtle but noticable difference.
I suppose it does depend on how modified your CDP is and also the type of opamp being used.

Class A generally gives a more musical sound as the distortion components are even harmonic as opposed to odd harmonics from class B (unless it is driven to clipping).

Having said that, Ray's discrete FET output is class A and would seem the route to go for the 'ultimate' uotput stage.

Andy
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Old 11th October 2006, 02:20 PM   #3995
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Hi
Any of you know what this is Surge protection

Brent
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Old 11th October 2006, 02:22 PM   #3996
SimontY is offline SimontY  United Kingdom
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Quote:
Originally posted by poynton
Having said that, Ray's discrete FET output is class A and would seem the route to go for the 'ultimate' uotput stage.

Andy
Sweet, well I hope to soon find out for myself how good it is!
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Old 11th October 2006, 03:10 PM   #3997
SimontY is offline SimontY  United Kingdom
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Here's my simple but hopefully very clear schematic that I made for my new power supplies. I thought it might be useful to other beginners to electronics. If you can see anything I could do better without major cost, please feel free to chip in.

Simon
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File Type: gif cdp external psu schematic.gif (21.9 KB, 283 views)
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Old 11th October 2006, 03:13 PM   #3998
poynton is offline poynton  United Kingdom
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Quote:
Originally posted by SimontY
Here's my simple but hopefully very clear schematic that I made for my new power supplies. I thought it might be useful to other beginners to electronics. If you can see anything I could do better without major cost, please feel free to chip in.

Simon
You forgot to include Rowe's toffee in a box !!

Andy
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Old 11th October 2006, 03:14 PM   #3999
poynton is offline poynton  United Kingdom
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Quote:
Originally posted by rowemeister
Hi
Any of you know what this is Surge protection

Brent

Bidirectional Silicon Transient Voltage Suppression Diodes
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Old 11th October 2006, 03:15 PM   #4000
SimontY is offline SimontY  United Kingdom
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Quote:
Originally posted by poynton
You forgot to include Rowe's toffee in a box !!

Andy
Hehe, I'd love to include a Russ Andrews Megaclamp. But that has to wait till we know what it is LOL
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