I didn't try this op amp yet, but in the data-sheet it looks quite good - 50V/mks slew rate, high open loop gain, linear phase response, etc.tbla said:
OP42 have quite hight level of distortions though (in the specification, but it is difficult to believe in those measurements, because the level is close to the level of limit for the measuring device), in comparison with the best known op amps, and IMO, based on the information in the specification, the performance of your device can be upgraded with replacement of them to OPA627 (if your CDP works in the oversampling mode with Digital Filter) or to faster AD811 if it uses DACs without DFs.
Due to the fact that we don't know the real level of distortions in OP42 at lower gains because of the performance of the measuring equipment, I am not sure if the difference after such modification can be ABX-ed though, as OP42 are definitely better then used in majority of CDPs generic op apms, where op amps swap is noticeable.
thank you gordon and others too, for taking time to read the datasheet for the op42 - and yes it looks ok so putting opa627 in its place doesn't seem so obvious.
and one more thing, the voltage used is 18,4V....!!!!!!
how will the opa627 react to that - any experience....?
there is also 4 servo opamps - the op27 from AD....?
btw you should see the clock in this very expensive player - it's a joke, it can't be made to a lower standard....it's definately the reason why this player sound so bad in some ways.
and one more thing, the voltage used is 18,4V....!!!!!!
how will the opa627 react to that - any experience....?
there is also 4 servo opamps - the op27 from AD....?
btw you should see the clock in this very expensive player - it's a joke, it can't be made to a lower standard....it's definately the reason why this player sound so bad in some ways.
I don't like this one so much , Carlos 🙁 I tried LM6172 and had found nothing special in it ... it can't compete with OPA627, IMO.carlosfm said:
This one is definitely very interesting (EDN's innovation of the Year 2003), but you can't replace pin-to-pin OP42 with it ...mandat said:
Agreed.tbla said:
OPA627 can handle +/-18V, but not much higher ...
Yes, clock is seriously related to the sound quality (we know this for a long time, right? 🙂 ), if you have any doubts in it - this is more important then op amps swap ... IMO.
tbla said:
It works fine at +/- 18v, no problems.
That voltage should not be a problem, but if you are worried about it you can use a small resistor in series with the PSU lines, before the bypass caps.
Gordon McGregor said:
I prefer the OPA627 too.
The LM6171/2 is a very good op-amp too, I like it.
It needs very careful psu bypassing.
The LM6171/2 gives me very good results as I/V.
It may depend on the Dac, circuit...
That's why I said to try it.
Tbla, try both, listen and decide what works better there.
Nobody will give a definitive answer for your question, you will have some suggestions, as I think was your intention.
Btw, have you noticed the lowsy PSRR of the OP42?😱
took out the op42 I/V opamps and put opa627bp in
+
took out the op27 servo opamps and put in opa627bp.
only the opams were touched, they are all bypassed with 10uF tantal caps - nothing else.
this replacement didn't do anything good to this players sound, now the sound is more light and hifi'ich and not as coherent as before.....less musical......
🙁
+
took out the op27 servo opamps and put in opa627bp.
only the opams were touched, they are all bypassed with 10uF tantal caps - nothing else.
this replacement didn't do anything good to this players sound, now the sound is more light and hifi'ich and not as coherent as before.....less musical......
🙁
What do you mean - "bypassed"? If you like that "coherent" kind of sound, you should probably use AD825 instead of OPA627 ... but anyway, the difference with OP42 could be inaudible ...tbla said:
......😱 .....sorry, i meant that the supplylines are decoupled with 10uF tantal caps.
perhaps another decoupling strategy would help...?
out with the tantals and in with the black gates or elna silmics.....?
and there is definately an audible difference - as the player totally changed character.
btw just between you and me - this player sounds a bit rough and digital but after it got a new clock it beats them all - believe me, i have tried almost every top player and none of them really sounds too good.
this krell has a formidable potential but don't tell anybody - the prices on the blue market will go skyhigh......😉
tbla said:
Take it easy, the work is not finished yet.😀
Take those tantalums out and put 47~100uf.
They like capacitance.
Bypass on the op-amp's pins with 0.1uf ceramics or poly.
Also, use 0.1~0.22uf poly directly between V+ and V- pins.
Are the existing caps near the op-amp's PSU pins?
Are they independent for each op-amp, or shared between the two?
The 627 needs attention.
the supply line has a 100ohm in series and the 10uF tantal to ground........
btw i could be tempted to make a small pcb with a ad8610 + regulators, remember the supply is 18V and there could be an advantage doin' it that way.....?
btw i could be tempted to make a small pcb with a ad8610 + regulators, remember the supply is 18V and there could be an advantage doin' it that way.....?
tbla said:
Why not just take the 100 ohm resistors out?
Make a small board with 15v regs and connect it to the place where the 100ohm resistors were mounted (input for the regs, output from the regs).
this player definately needs a new clock......alot.
you'll be amazed about its potential - after some mods it eats wadia 861, audio aero capitole, accuphase dp whatever and marantz cd7 for breakfast.........😀
you'll be amazed about its potential - after some mods it eats wadia 861, audio aero capitole, accuphase dp whatever and marantz cd7 for breakfast.........😀
tbla said:
What Dac chip does it use?
Anyway, have you compared it with a Linn CD12?
I've heard this player for quite a long time, on many occasions and it doesn't seam to need a clock.😀
It's just f-a-n-t-a-s-t-i-c.😎
But $$$$$$.
the krell had it for lunch yesterday........
no i'm just joking, i haven't tried a linn cd12.....
and it uses 4 x pcm63k.