OPA-627 vs. OPA604

[Tom D]

I'm hoping someone can help me out with understanding the major differences between these 2 Op-Amps.

Now I know that the OPA-627 is known to be superior to most op-amps and better than the OPA-604.

For example; for Headphone Amps. Would the OPA-627 be considered overkill for a Headphone Amp opposed to the OPA-604? Another words; if you were to compare these 2 op-amps with a certain Headphone Amp; would you be absolutely blown away by the OPA-627 and say it's a night and day difference?

Now, I know it's your ears that tell the true story; but is the much higher cost of the OPA-627 truely going to give you a "major" improvement for a Headphone Amp?

I hope someone can give an honest/subjective opinion. Thanks.

[Pan]

I have no experience with this opamp, but...

if my memory serves me right, I think several people over at headwize feel that the 627 is clearly better than the "cheaper" ones.

BTW, you should not drive the cans with an opamp, you should use a buffer. Check out Burr Browns own sugestion for a headphone amp. It uses OPA627 and BUF634.

/Peter

[joensd]

I´m using exactly the headphone amplifier from the BUF-634 datasheet with an OPA627 (oh, are those samples for me ).
I have to say it´s a very precise sounding system but I´ve heard much more "effervescent" sounding amps.
If I was to build another headphone amp I´d try the Zen headphone amplifier by Marcello Pellerano.
If I´d be asked to build a opamp headphone amp I´d use the OPA627/BUF634 combination again.
I don´t like the OPA604 at all. I´d prefer the OPA132/134 if you want something cheaper than OPA627.
For further designs and opinions about other opamps go headwize.
Loads of suggestions and good designs.

Jens

[peranders]

If you don't get the OPA627 for free I'd say OPA134 is a very cost effective choice. Check the example with OPA2604 (but change to OPA2134) and parallel connection. Haven't got the URL right now. Maybe someone else can help here?

[EchoWars]

I have done some mods to several 70's preamps in an attempt to update them a bit. One was my own Kenwood KA-5500, which uses +/-19V for preamp supply. There are only a handfull of opamps capable of running at this voltage, and the OPA2604 (dual version of OPA604) is one. Sounds wonderful...

Did another preamp where +/-15V was used, and sprung for a OPA627A. After swapping in the OPA604 and the OPA627 during listening tests, have to say the OPA627 is waaay overpriced. $15 for the 'A' and $23 for the 'B'...I don't think so. Differences in sound quality (to me...) are nearly nil.

If you can part with the cash, go for it. If you like reasonable solutions where a 'compromise' costs you near-nothing in sonics but saves you significant cash, then the OPA604 looks better all the time.

YMMV...

[peranders]

Originally posted by EchoWars
Did another preamp where +/-15V was used, and sprung for a OPA627A. After swapping in the OPA604 and the OPA627 during listening tests, have to say the OPA627 is waaay overpriced. $15 for the 'A' and $23 for the 'B'...I don't think so. Differences in sound quality (to me...) are nearly nil.

Overpriced, yes! It gives you not so much audio quality for the money (but it's real good!). The best price/performance ratio has NE5534! 4 SEK! (8,50 SEK = 1 USD)

[Tom D]

[QUOTE]Originally posted by EchoWars
[B] Differences in sound quality (to me...) are nearly nil.

So; Would you say that if you could buy a Headphone Amp made with the OPA604's and the same Headphone Amp made with the OPA627's; Would you pay another $300+ more for the Amp that was no different except for the OPA627's? Another words; You have the same exact Amp side by side, swap out the OPA604's with the OPA627's.

This is in respect to someone buying a fully assembled Amp from a manufacturer opposed to a DIY person who of course could save a lot of Money by doing this themselves.

[EchoWars]

If you read my post, you already know the answer.

[bilavideo]

This is Bill from the future. When I rolled in a pair of 604s, they sounded awful till I doubled the power (from 9V to 18V). After a short burn-in, they went from grainy to absolutely amazing. Their emphasis on midrange revealed all kinds of details that had me howling with delight. Here in the future, they're still cheaper than the 627s, but at least you can now order 627s premounted into adapters from Browndog/cimmaron.

In the future, a pair of 627AUs premounted to a two-sided adaptor will cost you $48.

[analog_sa]

Originally posted by bilavideo
they sounded awful till I doubled the power (from 9V to 18V).

Imagine what they would sound like if you tripled the power.

Originally posted by bilavideo
In the future, a pair of 627AUs premounted to a two-sided adaptor will cost you $48.

That's presumably after three years of quantitative easing. Let us have the good news then: did house prices go up big time?