OPA604 to OPA627..some problems

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hifive said:
I've changed my Naim CD5 OPA 604 to OPA 627 and the improvements was good. But the only issue is in the vocal "ssss" too sharp. How should I rectify that...


Thanks

You can try decoupling from V+ to V- with npo 0.1 u ceramic and or decoupling to 0 rail. I personally don't like the dry character of the 627 and prefer class A bias on AD825 or heavilly dceoupled LM6171.

You should not always believe what you read about the 627


:hot:
 
Re: Re: OPA604 to OPA627..some problems

fmak said:


You can try decoupling from V+ to V- with npo 0.1 u ceramic and or decoupling to 0 rail. I personally don't like the dry character of the 627 and prefer class A bias on AD825 or heavilly dceoupled LM6171.

You should not always believe what you read about the 627


:hot:


With you there, the AD825 has killer transients and powerful tight bass, yet remains smooth as silk because it runs stinking hot in a lot of Class A, wish they made small SMD heatsinks for these. they really need them.

Cheers George
 
Re: Re: Re: OPA604 to OPA627..some problems

georgehifi said:



With you there, the AD825 has killer transients and powerful tight bass, yet remains smooth as silk because it runs stinking hot in a lot of Class A, wish they made small SMD heatsinks for these. they really need them.

Cheers George

How did you bias the AD825 to class A ??

For heatsinks, use u-shaped alloy channel available from hardware shops epoxyed to the chip. It overlaps a little but you can still solder. Brass channel is also available from model shops.

Andy
 
Re: Re: Re: Re: OPA604 to OPA627..some problems

poynton said:


How did you bias the AD825 to class A ??

For heatsinks, use u-shaped alloy channel available from hardware shops epoxyed to the chip. It overlaps a little but you can still solder. Brass channel is also available from model shops.

Andy

Running at -15 +15 they run quite hot to the touch, (and no, they're not oscillating) to the point of wanting to cool them with a heat sink. OPA134,OPA2134 & OPA4134's SMD's, run this hot and also sound great, but the AD825's have better slam.

Cheers George
 

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