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Macpibe 20th June 2007 03:41 AM

Yamaha amplifier Upgrade
 
Hi
I wish to upgrade my old Yamaha A-560 amplifier. I started for change the OP in the preamp (JRC4559) for a NE5532, because I read that are fast in the spec sheet (Slew rate: 8 V/µS NE5532 – 2 V/µS JRC 4559).
I see here that are many others Ops that are better, like the OPA249, AD8032, or best THS4032 and some LMH-types.
My question will be if this others best Ops perform well in a pre designed in my modest Yamaha amplifier to work with the original JRC4559. If not, I must modify my pre in other way?
Thanks to this excellent forum and for any comments,
Regards.

anatech 21st June 2007 01:34 AM

Hi Macpibe,
Keep in mind that the 4559 is a pretty good op amp. There are many more factors to look at. Having said that, the NE5532 is a good sounding op amp. You could certainly try it. I honestly don't know if you will hear a difference.

Correct me if I'm wrong, but is that op amp used in the phono section? I thought the tone controls were operated in the main feedback loop. If this is the case, I doubt this will make any difference on high level inputs. I'm just going off memory here.

-Chris

Macpibe 21st June 2007 11:20 PM

Thanks Chris,
And yes, this op amp is used in the phono pre amp section.
Unfortunately I don’t have the schematic circuit of this amplifier (If any can tell me where find this in the web..thanks…) and can’t see how the tone control works..
But, in any case, you think that I can’t hear the difference between others (best) OP amps?
Thanks again,
Carlos.

anatech 22nd June 2007 10:22 PM

Hi Carlos,
Better op amps may make a difference. Look for low noise parts. I believe those were were numbered 4559DD, a quiet version.

You should be able to find that data sheet by using a search engine like google.

-Chris

Iván Francisco 23rd June 2007 12:32 AM

Hi Macpibe:

if you can pay $14,99, you can get the service manual at

http://www.user-manuals.com/service-...MAHA-A560.html

Cheers, hermano

Iván Francisco 23rd June 2007 12:44 AM

Sorry, Macpibe I forgot, you can post it at

http://www.yoreparo.com/foros/repara...dio/index.html

(remember login first) and ask for the manual too.

Bye,
Iván

Macpibe 23rd June 2007 02:50 AM

2 Attachment(s)
Gracias Ivan, intentare por ahi...
And for Chris (if you want answer) or anybody, in a phono pre amp design like this (attachment), which OP amp will be better to replace the original JRC4559D? an OPA2134 (FET input) or an LM4562 ?
Many thanks.

anatech 23rd June 2007 02:55 AM

Hi Carlos,
That's a hard question to answer. The dual fet pair really loosens the job on the op amp. In this circuit you will need good drive capability. Super high slew rates are not critical either. Try them both if you want. I don't know how it will react to a fet input, but it may work just fine. Measure the hiss level on the tape out when you try them. Also, listen and pick what you like the best. Don't worry if you don't hear a difference either. Watch for oscillations.

I'd be interested to know if you do hear a difference.

-Chris

XEAGLEKEEPER 23rd June 2007 05:03 AM

Going to faster OP's may require other mod's to eliminate oscillation of the OP's

Nordic 23rd June 2007 05:23 AM

2 Attachment(s)
opamp chart


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