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  #1  
Old 19-05-17, 01:11 PM
Bigman80 Bigman80 is offline
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Op Amps

Hi all,

This is my first post so forgive me if it's in the wrong area!!


Have any of you had any experience with SS3602 Discrete opamps?

heres a link: http://sparkoslabs.com/product/discrete-op-amp-ss3602/

I've ordered a couple based on the reviews. The reviews are very complimentary but a few unbiased opinions would be welcome!

Thanks in advance

Last edited by Bigman80; 19-05-17 at 01:14 PM. Reason: spelling error
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  #2  
Old 21-05-17, 02:29 AM
Julf Julf is offline
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I guess it all depends on what you want to use them for...
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Old 21-05-17, 10:21 AM
S-Man S-Man is offline
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At least the data sheet is reasonably comprehensive, which is not always the case with these type of things.

Must admit I would be interested to try them, but not at $80 each. Especially as my favourite opamps on his list are the ones with the worst figures

Let us know how you get on, and as Julf says, where they are going to be used and what they are replacing.
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  #4  
Old 21-05-17, 12:50 PM
russel russel is offline
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LME49724 LME49600 LME49720 LME49860 LME49710 LM4562 OPA1632
2.1 3 2.5 2.5 2.5 2.7 1.3 all nV sqrt Hz


I notice he has left some of the op-amps with lower noise off his table, they may be very good and maybe better but I am not sure about super expensive op amps since the ones listed above are a bit too new for recording studios, most of the music you listen to will have been through a 5534 or more likely a 5532 at some point. You can get good results from analog devices or Ti parts for a lot less money.
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  #5  
Old 21-05-17, 02:11 PM
Andrew.B Andrew.B is offline
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I went though a phase of 'rolling' opamps, and unlike many I was actually using legit parts direct from Ti, etc, not reprinted Chinese spiders, and gave up because I honestly didn't have a clue what I was doing, swapping opamps in and out of random circuits just seemed silly and I had no idea what was going on, and when the hierarchy began to emerge, realised it was a load of audiophool BS.

The sight of those first discreet opamps, boards stuffed with though hole components with measurements so terrible, hanging off tiny 8 pin sockets was kinda funny though, certainly looked very impressive, great for selling a blurb. Glad they've adopted SMD.
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Old 21-05-17, 04:37 PM
davidsrsb davidsrsb is online now
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Forty years ago there was a real market for discrete opamps, as it was not possible to integrate a decent pnp transistor -709 and 741 were terrible. This went away when Harris introduced their dielectric isolated process with workable pnp devices and since then discrete only made sense when you wanted an unusual feature like high supply voltage.

I noticed that this model won't work on +/- 5V and has very high input current
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Old 21-05-17, 07:08 PM
audiopile audiopile is offline
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Bryston Discrete Op-amp

One company that has continued to use (quit successfully) the discrete opamp is Bryston. I suspect that this is one of the reasons they are very reasonable about publishing their schematics (something I appreciate!). Wonder how many attempts are made to order those Bryston op amp numbers from parts suppliers ?
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Old 23-05-17, 01:39 AM
Bigman80 Bigman80 is offline
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Well, I have some of theses on the way too.....

https://www.bursonaudio.com/products...und-opamp-v5i/

They are for use in a phono stage. Ideally ultra low noise Opamps are desired.

Any recommendations?
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  #9  
Old 23-05-17, 06:17 AM
davidsrsb davidsrsb is online now
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Analog Devices are making fairly cheap parts like the ADA4897-2, with remarkable specs. 1nV/rtHz and 230MHz GBw and only 2.4nV/rtHz at 10Hz. This is enough to compete with unobtanium 2SK170 designs in MC preamplifiers. These make the discrete opamps look a bit limited
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  #10  
Old 23-05-17, 11:32 AM
demotivated demotivated is offline
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Quote:
Originally Posted by davidsrsb View Post
Analog Devices are making fairly cheap parts like the ADA4897-2, with remarkable specs. 1nV/rtHz and 230MHz GBw and only 2.4nV/rtHz at 10Hz. This is enough to compete with unobtanium 2SK170 designs in MC preamplifiers. These make the discrete opamps look a bit limited
It might be low voltage noise at the expense of highish current noise and therefore not ideal for low impedance inputs, but it is astounding specs - 230MHz gbw in an audio friendly part, wow.

edit - just read up the datasheet and it's another decade ahead of my electronics experience - amazing.

Last edited by demotivated; 23-05-17 at 11:35 AM. Reason: just read the sheet..
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  #11  
Old 23-05-17, 12:59 PM
martin clark martin clark is offline
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Phenomenal specs are one thing; actually delivering it in-situ can be quite another!

Implementing really fast/really-quiet opamps takes great finesse in layout and decoupling, and some savvy and test gear to check stability (at the very least). It's why 'rolling' op-amps generally/blindly is a complete crapshoot - most of the reported differences are about differing sensitivities to the implementation it has been plunked into, rather than any measure of opamp 'goodness' (for want of a better description.)

There are multiple, interacting dimensions at work; picking by datasheet top-trumps is no guide at all - unless you can define which parameters really matter / have some inkling as to which ones the circuit you are playing with is sensitive-to. A short list of examples for the sake of handwaving: the audiophool faves of slew rate and noise, for a start are very rarely good 'picks' (you want the slowest opamp that will do the job well-enough, for all sorts of reasons; and in line-level circuits, noise is usually limited by other issues than any modest op-amp can offer. A subject for another day); PSRR might matter, but PSRR at 10k-100kHz might be more interesting in the circuit you are playing with; and in a filter it might just be CMRR and/or GBW are key parameters above all, depending on filter design...

Last edited by martin clark; 23-05-17 at 01:09 PM.
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  #12  
Old 23-05-17, 04:42 PM
davidsrsb davidsrsb is online now
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You cannot just drop this AD part in place of a NE5532 in your CD player, you need to consider supply voltage - modern parts are for a +/-5V world or even lower and with 230MHz bandwidth, forget putting it on a single layer board with long tracks and no local decoupling
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  #13  
Old 24-05-17, 12:42 AM
S-Man S-Man is offline
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Quote:
Originally Posted by martin clark View Post
Phenomenal specs are one thing; actually delivering it in-situ can be quite another!

Implementing really fast/really-quiet opamps takes great finesse in layout and decoupling, and some savvy and test gear to check stability (at the very least). It's why 'rolling' op-amps generally/blindly is a complete crapshoot - most of the reported differences are about differing sensitivities to the implementation it has been plunked into, rather than any measure of opamp 'goodness' (for want of a better description.)

There are multiple, interacting dimensions at work; picking by datasheet top-trumps is no guide at all - unless you can define which parameters really matter / have some inkling as to which ones the circuit you are playing with is sensitive-to. A short list of examples for the sake of handwaving: the audiophool faves of slew rate and noise, for a start are very rarely good 'picks' (you want the slowest opamp that will do the job well-enough, for all sorts of reasons; and in line-level circuits, noise is usually limited by other issues than any modest op-amp can offer. A subject for another day); PSRR might matter, but PSRR at 10k-100kHz might be more interesting in the circuit you are playing with; and in a filter it might just be CMRR and/or GBW are key parameters above all, depending on filter design...
Completely agree!!

And from a subjective viewpoint -IMO the decoupling makes more difference to the sound than changing the opamp. It's difficult to measure any differences when changing decoupling, and of course it's all dependent on the layout.
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  #14  
Old 24-05-17, 01:47 AM
davidsrsb davidsrsb is online now
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Quote:
Originally Posted by S-Man View Post
And from a subjective viewpoint -IMO the decoupling makes more difference to the sound than changing the opamp. It's difficult to measure any differences when changing decoupling, and of course it's all dependent on the layout.
I used to design video amplifiers and tested with a frequency sweep up to 10MHz in the TV line. It was very clear on the test equipment displays how decoupling changes could cause small ripples in the sweep amplitude.
Applications like DAC IV converters contain high frequencies than video.
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  #15  
Old 24-05-17, 03:16 AM
S-Man S-Man is offline
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And could you correlate the measurements with picture quality?

I suspect it will be quite hard to meaure any differences with typical DIY test gear and in a phono stage (which is the op's application).

BTW Bigman - you should be very careful indeed if you are thinking of using the Sparko with dc coupling as the 1st stage of an MC amp!
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