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View Full Version : Parallel different op amps opa 2604 and 2107



Light Dependant Resistor
09-11-2019, 11:20
Hi
The opa2107 is one of my favourite op amps , tonight though I listened to a opa2604 in a Pioneer PDS507 Legato Link Stable platter Cd player.
The opa2604 has a great way of following bass notes and rhythms, it also has very good bass accuracy but is not as open as the opa2107,
so you have to listen quite a while to pick up what it is good at.

The PDS507 was pretty easy to solder in a turned pin socket, its circuit board only taking a few minutes to invert to access the
original op amp position. Anyway what if we parallel a opa2604 with a opa2107 soldering one to the other , it would seem the best of both worlds was
then possible, -incredible detail from the opa2107 and really nice bass definition from the opa2604. and that's exactly what happened.

On some application notes op amp manufacturers recommend using low value resistors to share output loads where parallel op amps are used.
But the benefits of each op amp is easily heard, just with a direct parallel. To my ears a really nice relatively inexpensive upgrade that no usual
op amp rolling could even approach.

Lawrence001
09-11-2019, 11:26
I've recently replaced 6(!) Op amps in my Chinese dac with genuine BB OPA627APs. The upgrade was obvious compared to the (presumed) fakes that were fitted as stock. Where do you think these stand in the grander scheme of things?

Bear in mind I couldn't afford 6 Bursons or similar discrete op amps. I did look at the cheap Chinese discrete ones on eBay but online reviews implied they weren't very good.

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Light Dependant Resistor
09-11-2019, 11:45
I've recently replaced 6(!) Op amps in my Chinese dac with genuine BB OPA627APs. The upgrade was obvious compared to the (presumed) fakes that were fitted as stock. Where do you think these stand in the grander scheme of things?

Bear in mind I couldn't afford 6 Bursons or similar discrete op amps. I did look at the cheap Chinese discrete ones on eBay but online reviews implied they weren't very good.

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To my ears the combination of 2604 and 2107 provides a better audio experience than any single op amp can manage.
I have heard opa627 I use them in a Net audio Mk3 Quad 405 boards, they also have a nice way of portraying depth and bass

To build the 2604 and 2107 as one, I set mine up in a blank pcb and soldered the legs one at a time to join the devices, taking care
not to solder the blank pcb as well. the job only took a few minutes. the two op amps will be about a tenth the cost of a opa627
so worth giving it a go.

Light Dependant Resistor
09-11-2019, 12:16
Noting the 2604 and 2107 are dual type op amps, not singles. the 627 is a single type

I am unsure of an exact equivalent to the 2107 in single but the 2604 in a single is the opa 604 https://www.ti.com/lit/ds/symlink/opa604.pdf

The 2107 is close i know to the opa111 but the one's I have seen were can types - but could be
done. If attempting I would put the 604 on the bottom using a turned pin socket and opa 111 on top
and carefully follow its pinout from the outer tab. http://www.ti.com/product/OPA111

Lawrence001
09-11-2019, 12:32
Thanks sounds very complicated I'm just looking at drop in replacements so I've probably got pretty good ones already.

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M6NTL
09-11-2019, 12:59
That's REALLY cool..!!..

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