Author Topic: QRV-08 OP Amp replacement  (Read 3253 times)

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Offline alexanderbax

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QRV-08 OP Amp replacement
« on: January 31, 2017, 11:11:58 AM »
Hi Per-Anders

Just a quick question with regards to the QRV-08 headphone amp I will be building soon.  Im just going through the BOM and getting all the parts sourced before I place any orders.  Just a quick question on mainly the Op amp (OPA134) but also a couple of other things.  I know its difficult as a lot of this will be subjective and you might not have tried different configurations but Id like to get your opinions:

1)  Would there be any conceivable benefit to replacing the basic OPA134 with something more optimised, such as https://www.bursonaudio.com/products/supreme-sound-opamp-v5/ ?

2)  Would powering it with a low powered r-core or toroidal transfomer make any difference?

3)  Any benefit to upgrading the PSU caps, to say Mundorf spec?

Thanks for your help

Alex

Offline peranders

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Re: QRV-08 OP Amp replacement
« Reply #1 on: January 31, 2017, 06:52:23 PM »
1 The DC servo will have some influence on the performance up to approx. 1 kHz. The OPA134 is a bit overkill infact. A good opamp with good DC performance and a bit slow speed will also work.

2 Can't but won't harm either. Use it if you'll like it.

3 Can't tell, probably not.
/Per-Anders Sjöström, owner of this forum

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Offline alexanderbax

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Re: QRV-08 OP Amp replacement
« Reply #2 on: January 31, 2017, 07:22:51 PM »
Thanks Pers.  Last question..... are there suitable alternatives (that wont degrade sound quality) to the six 100nf PPS caps (C1, C16, C17 for one side)?  These are really expensive (and hard to get hold of in the UK) and I can only seem to buy them in 10s.  Would a PEN (polyethelyne naphthlate) dielectric be ok here (or even a Polyester, although I would rather not do that).

Offline alexanderbax

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Re: QRV-08 OP Amp replacement
« Reply #3 on: January 31, 2017, 07:26:45 PM »
Actually to be more specific, its the size I am struggling with.  There are quite a few PPS SMD caps I can get but its the size 2220 that is very difficult.  Without seeing the size of the solder pads, is there an alternative sized PPS cap I could get as an alternative?

Offline peranders

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Re: QRV-08 OP Amp replacement
« Reply #4 on: January 31, 2017, 08:38:38 PM »
PEN is polyester :) Will also work OK.
/Per-Anders Sjöström, owner of this forum

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