Discrete OpAmp Review: Sonic Imagery vs Sparkos

[KSTR]

Normally you'd regularily search in the manufacturers new product listings first for any new interesting products. The OPA1656 immediately raised my attention, plus there was/is a long thread about it on diyaudio.com with a TI insider involved.
It's a killer OpAmp, and better suited to non-inverting buffer duties than the OPA1612/2211

 

[jokan]

Normally you'd regularily search in the manufacturers new product listings first for any new interesting products. The OPA1656 immediately raised my attention, plus there was/is a long thread about it on diyaudio.com with a TI insider involved.
It's a killer OpAmp, and better suited to non-inverting buffer duties than the OPA1612/2211

I see, thanks for the information. I still love my 1656's, they're on my old CD players RCA outputs replacing the original burr brown, pre TI op-amps. And I tried the bursons using their extension as it was the only way to make them fit physically. With the lid off, I couldn't hear any significant difference, but that could be due to the layout and use. (probably is). Not a single store in Tokyo that specialises in parts for the DIY'er has them or knows about the 1656 which I find extremely odd.

Thanks again for the info!

 

[BR52]

Normally you'd regularily search in the manufacturers new product listings first for any new interesting products. The OPA1656 immediately raised my attention, plus there was/is a long thread about it on diyaudio.com with a TI insider involved.
It's a killer OpAmp, and better suited to non-inverting buffer duties than the OPA1612/2211

Hello, op amp rolling can be really a nice sport specially some more modern popping up. However, it would be to have a good understanding about the circuit they have to work in. In low input impedance circuits for example i/v converter the OPA 1611/12 is a perfect solution.
On the other side in high input impedance circuits for example the OPA 1656 is the best solution.
To do the calculations this will explain a lot : https://www.ti.com/lit/an/slyt470/slyt470.pdf?ts=1622547957789
There is no "best one" we have always take care of the circuit they are working in.

Best

 

[David_M]

Maybe @JohnYang1997 can tell us more about his new discrete opamp that defies the latest AP instrument?

 

[Matias]

Objective Guide to Op-Amp Rolling - Part 1

https://orchardaudio.com/blog/f/objective-guide-to-op-amp-rolling---part-1

 

[David_M]

THD+N


THD no N just for consistency and resolution

The OPA1612 has great specs at or below 1 KHz but "breaks down" by 10Khz and above. Can you please show the THDN plots at 10kHz or 20kHz? Thanks!

 

[TCD333]

The OPA1612 has great specs at or below 1 KHz but "breaks down" by 10Khz and above. Can you please show the THDN plots at 10kHz or 20kHz? Thanks!

View attachment 144553

Exactly. Measuring opamps (and amplifiers) at low signal level and in particular 1kHz is of fairly limited value because they all invariably measure very well at this freq before the compensation network starts to significantly chew up all the open loop gain used for reducing distortion.
These two opamps have different but effective ways to enhance HF distortion reduction compared to traditional chip opamps. The Sparkos uses a two pole compensation network referenced to ground. The SIL uses small inductors on IP transistors. Both methods generally increase open loop gain up to around 65 - 100 kHz then it will taper off more quickly than a traditional single order compensated opamp. The latter method used in SIL was first used in the famous (Deane) Jensen 990 discrete opamp many years ago. These days the advantage of a discrete opamp are questionable due to the incredible performance of the best chips - like the 1612. Probably the best current discrete opamp would be the Weiss OP1-BP which does indeed have measured performance better than any chip opamp I'm aware of.

 

[Veri]

Probably the best current discrete opamp would be the Weiss OP1-BP which does indeed have measured performance better than any chip opamp I'm aware of.

Wow, that thing has some superb specs.

 

[BR52]

These days the advantage of a discrete opamp are questionable due to the incredible performance of the best chips - like the 1612.

I have an idea: a super-duper dac with Ess 9038 pro and a topology like Gustard x18 DAC

this will need 32! Weiss OP1 BP . I am kidding.

Additionally I can see in some implementations of discrete op amps some design flaws. Like the decoupling capacitors far away from the op, simple pcb layout, no ground plane and so on. And then we discuss about the part not about the whole thing.

 

[TCD333]

I have an idea: a super-duper dac with Ess 9038 pro and a topology like Gustard x18 DAC

this will need 32! Weiss OP1 BP . I am kidding.

Additionally I can see in some implementations of discrete op amps some design flaws. Like the decoupling capacitors far away from the op, simple pcb layout, no ground plane and so on. And then we discuss about the part not about the whole thing.

WRT decoupling, you are right especially on OPA's that have pretty high GBW. Many discrete OPA's have on board decoupling, ground pin being a typical giveaway. The OP1 BP is actually ideal for DACs like 9038 pro and AK4499 because it can handle the high current swing.
It may appear that I'm putting down discrete opamps but, as always things are not quite so simple as they might seem.
Discrete circuitry and opamps have been used in pro audio forever and span a range from very simple, fairly high distortion to super pristine clean.
To go even further down this path, many of the designs I use are actually open loop, IOW do not even use opamps, global or local feedback. This may sound crazy but when done right, the sonic result in a recording chain and often in playback can sound really good. So then the argument will ensue, it's not supposed to sound like anything... and I can tell you through many years of experience that put a signal chain from mic to playback that has zero distortion and 9 times out of 10 it will not sound very good. It's complicated. Best read Amir's test of the reel to reel, look at the terrible measurements and note the comments WRT what people thought of the sound.

 

[BR52]

Oh! Yes, it's a different approach to add some k(n) to the signal, or you try to add nothing. In the first case you create a "music instrument" like different piano brands or even pianos have a different (brand) sound. Or you try to add nothing (or not measurable).
For my self, I have a Tube amplifier and a Purifi . For my understanding, this forum is pushing the second approach. Because the first one has to do with emotions.
For the second approach, I'm missing more analytical methods for the whole chain. But this is unfortunately
very individual, caused by the countless permutations of good measuring building blocks.

 

[David_M]

Wow, that thing has some superb specs.

But there's a catch and I believe this is a marketing gimmick used a lot ... you can get superb distortion and noise specs for high input signals. This amp's excellent THD+N specs are only possible at high +22dBu or 21 Vpp or 7.75Vrms levels. While these levels are ideal for low gain amplifiers, such as the Purifi amps, most high amps require a maximum of 2Vrms (and often lower at 1.6Vrms) to come to full power.

If the OP1 is linear, and there's no reason to believe it's not, then its THD+N specs at the nominal 2.0vrms output level are:

THD+N@ 2vrms = [email protected] + 20 * log10 (7.75/2.0) = -152dB + 12 dB (...but actually ~11.76) = -140dB at 1KHz

THD+N@ 2vrms = [email protected] + 20 * log10 (7.75/2.0) = -148dB + 12 dB (...but actually ~11.76) = -136dB at 10KHz

Still excellent numbers, btw, if they can be consistently maintained in an actual high-volume production run.

Anyways, I don't think this amp is still manufactured as it's not on the product line on the company website.

 

[TCD333]

But there's a catch and I believe this is a marketing gimmick used a lot ... you can get superb distortion and noise specs for high input signals. This amp's excellent THD+N specs are only possible at high +22dBu or 21 Vpp or 7.75Vrms levels. While these levels are ideal for low gain amplifiers, such as the Purifi amps, most high amps require a maximum of 2Vrms (and often lower at 1.6Vrms) to come to full power.

If the OP1 is linear, and there's no reason to believe it's not, then its THD+N specs at the nominal 2.0vrms output level are:

THD+N@ 2vrms = [email protected] + 20 * log10 (7.75/2.0) = -152dB + 12 dB (...but actually ~11.76) = -140dB at 1KHz

THD+N@ 2vrms = [email protected] + 20 * log10 (7.75/2.0) = -148dB + 12 dB (...but actually ~11.76) = -136dB at 10KHz

Still excellent numbers, btw, if they can be consistently maintained in an actual high-volume production run.

Anyways, I don't think this amp is still manufactured as it's not on the product line on the company website.

There's no marketing gimmick that I'm aware of. At lower voltage swings generally the distortion will be lower and then noise will dominate
the figure but the distortion itself will almost always be lower. The design really is cutting edge and the data sheet does unveil a few of the secrets but you have to be able to interpret it. The only reservation I have is the phase margin looks a bit marginal so at low gains / unity it might be tricky.

 

[Ashley Salmond]

I have post plenty on my hearing abilities in the past including passing some of the most challenging tests ever put online. Here are results of such double blind tests conducted using ABX tool in Foobar2000.

Archimago test of 16 bits versus 24 bits:
foo_abx 1.3.4 report
foobar2000 v1.3.2
2014/08/02 13:52:46

File A: C:\Users\Amir\Music\Archimago\24-bit Audio Test (Hi-Res 24-96, FLAC, 2014)\01 - Sample A - Bozza - La Voie Triomphale.flac
File B: C:\Users\Amir\Music\Archimago\24-bit Audio Test (Hi-Res 24-96, FLAC, 2014)\02 - Sample B - Bozza - La Voie Triomphale.flac

13:52:46 : Test started.
13:54:02 : 01/01 50.0%
13:54:11 : 01/02 75.0%
13:54:57 : 02/03 50.0%
13:55:08 : 03/04 31.3%
13:55:15 : 04/05 18.8%
13:55:24 : 05/06 10.9%
13:55:32 : 06/07 6.3%
13:55:38 : 07/08 3.5%
13:55:48 : 08/09 2.0%
13:56:02 : 09/10 1.1%
13:56:08 : 10/11 0.6%
13:56:28 : 11/12 0.3%
13:56:37 : 12/13 0.2%
13:56:49 : 13/14 0.1%
13:56:58 : 14/15 0.0%
13:57:05 : Test finished.

----------
Total: 14/15 (0.0%)

0.0% chance of guessing.

Difference between 24/96 kHz and 16/44.1 with file provided by the late ArnyK:
foo_abx 1.3.4 report
foobar2000 v1.3.2
2014/07/24 20:27:41

File A: C:\Users\Amir\Music\Arnys Filter Test\keys jangling amir-converted 4416 2496.wav
File B: C:\Users\Amir\Music\Arnys Filter Test\keys jangling full band 2496.wav

20:27:41 : Test started.
20:28:07 : 00/01 100.0%
20:28:25 : 00/02 100.0%
20:28:55 : 01/03 87.5%
20:29:02 : 02/04 68.8%
20:29:12 : 03/05 50.0%
20:29:20 : 04/06 34.4%
20:29:27 : 05/07 22.7%
20:29:36 : 06/08 14.5%
20:29:44 : 07/09 9.0%
20:29:55 : 08/10 5.5%
20:30:00 : 09/11 3.3%
20:30:07 : 10/12 1.9%
20:30:16 : 11/13 1.1%
20:30:22 : 12/14 0.6%
20:30:29 : 13/15 0.4%
20:30:36 : 14/16 0.2%
20:30:41 : 15/17 0.1%
20:30:53 : 16/18 0.1%
20:31:03 : 17/19 0.0%
20:31:07 : Test finished.

----------
Total: 17/19 (0.0%)

0.0% probably of chance.

320 kbps version of above against the original (ran as a challenge by someone as being impossible):
foo_abx 1.3.4 report
foobar2000 v1.3.2
2014/07/19 19:45:33

File A: C:\Users\Amir\Music\Arnys Filter Test\keys jangling 16 44.wav
File B: C:\Users\Amir\Music\Arnys Filter Test\keys jangling 16 44_01.mp3

19:45:33 : Test started.
19:46:21 : 01/01 50.0%
19:46:35 : 02/02 25.0%
19:46:49 : 02/03 50.0%
19:47:03 : 03/04 31.3%
19:47:13 : 04/05 18.8%
19:47:27 : 05/06 10.9%
19:47:38 : 06/07 6.3%
19:47:46 : 07/08 3.5%
19:48:01 : 08/09 2.0%
19:48:19 : 09/10 1.1%
19:48:31 : 10/11 0.6%
19:48:45 : 11/12 0.3%
19:48:58 : 12/13 0.2%
19:49:11 : 13/14 0.1%
19:49:28 : 14/15 0.0%
19:49:52 : 15/16 0.0%
19:49:56 : Test finished.

----------
Total: 15/16 (0.0%)

0.0% chance of guessing.

Ethan Winer test of audibility of multiple passes through ADC/DAC (most difficult: single pass one):

foo_abx 1.3.4 report
foobar2000 v1.3.2
2014/07/18 06:40:07

File A: C:\Users\Amir\Music\Ethan Soundblaster\sb20x_original.wav
File B: C:\Users\Amir\Music\Ethan Soundblaster\sb20x_pass1.wav

06:40:07 : Test started.
06:41:03 : 01/01 50.0%
06:41:16 : 02/02 25.0%
06:41:24 : 03/03 12.5%
06:41:33 : 04/04 6.3%
06:41:53 : 05/05 3.1%
06:42:02 : 06/06 1.6%
06:42:22 : 07/07 0.8%
06:42:34 : 08/08 0.4%
06:42:43 : 09/09 0.2%
06:42:56 : 10/10 0.1%
06:43:08 : 11/11 0.0%
06:43:16 : Test finished.

----------
Total: 11/11 (0.0%)

0.0% chance of guessing.

Audibility of low frequency jitter challenge as again provided by the late Arnyk:
foo_abx 1.3.4 report
foobar2000 v1.3.2
2014/07/09 09:31:59

File A: C:\Users\Amir\Music\Arny's 30 Hz Jitter File\Arny's new files\no jitter.wav
File B: C:\Users\Amir\Music\Arny's 30 Hz Jitter File\Arny's new files\30 Hz jitter marginal level .00625.wav

09:31:59 : Test started.
09:32:47 : 01/01 50.0%
09:32:58 : 02/02 25.0%
09:33:09 : 03/03 12.5%
09:33:22 : 04/04 6.3%
09:33:33 : 04/05 18.8%
09:34:03 : 05/06 10.9%
09:34:18 : 06/07 6.3%
09:34:30 : 07/08 3.5%
09:34:46 : 08/09 2.0%
09:34:56 : 08/10 5.5%
09:35:19 : 09/11 3.3%
09:35:34 : 10/12 1.9%
09:35:49 : 11/13 1.1%
09:36:38 : 12/14 0.6%
09:37:21 : 12/15 1.8%
09:37:41 : 13/16 1.1%
09:37:52 : 14/17 0.6%
09:38:13 : 15/18 0.4%
09:38:26 : 16/19 0.2%
09:38:39 : 17/20 0.1%
09:38:45 : Test finished.

----------
Total: 17/20 (0.1%)

0.1% chance of guessing.

Public challenge on AVS Forum on differences between 24 bit/96 kHz and CD rate with content from AIX:
foo_abx 1.3.4 report
foobar2000 v1.3.2
2014/07/10 18:50:44

File A: C:\Users\Amir\Music\AIX AVS Test files\On_The_Street_Where_You_Live_A2.wav
File B: C:\Users\Amir\Music\AIX AVS Test files\On_The_Street_Where_You_Live_B2.wav

18:50:44 : Test started.
18:51:25 : 00/01 100.0%
18:51:38 : 01/02 75.0%
18:51:47 : 02/03 50.0%
18:51:55 : 03/04 31.3%
18:52:05 : 04/05 18.8%
18:52:21 : 05/06 10.9%
18:52:32 : 06/07 6.3%
18:52:43 : 07/08 3.5%
18:52:59 : 08/09 2.0%
18:53:10 : 09/10 1.1%
18:53:19 : 10/11 0.6%
18:53:23 : Test finished.

----------
Total: 10/11 (0.6%)

0.6% chance of guessing (anything less than 5% is good enough)

Another track from same challenge:
foo_abx 1.3.4 report
foobar2000 v1.3.2
2014/07/10 20:56:12

File A: C:\Users\Amir\Music\AIX AVS Test files\Just_My_Imagination_A2.wav
File B: C:\Users\Amir\Music\AIX AVS Test files\Just_My_Imagination_B2.wav

20:56:12 : Test started.
20:57:10 : 00/01 100.0%
20:57:21 : 01/02 75.0%
20:57:30 : 02/03 50.0%
20:57:41 : 03/04 31.3%
20:57:51 : 03/05 50.0%
20:58:02 : 04/06 34.4%
20:58:12 : 05/07 22.7%
20:58:19 : 06/08 14.5%
20:58:29 : 07/09 9.0%
20:58:40 : 08/10 5.5%
20:58:50 : 09/11 3.3%
20:59:00 : 10/12 1.9%
20:59:09 : 11/13 1.1%
20:59:19 : 12/14 0.6%
20:59:30 : 13/15 0.4%
20:59:41 : 13/16 1.1%
20:59:57 : Test finished.

----------
Total: 13/16 (1.1%)

1.1% chance of guessing.

Another track from same challenge:
foo_abx 1.3.4 report
foobar2000 v1.3.2
2014/07/11 06:18:47

File A: C:\Users\Amir\Music\AIX AVS Test files\Mosaic_A2.wav
File B: C:\Users\Amir\Music\AIX AVS Test files\Mosaic_B2.wav

06:18:47 : Test started.
06:19:38 : 00/01 100.0%
06:20:15 : 00/02 100.0%
06:20:47 : 01/03 87.5%
06:21:01 : 01/04 93.8%
06:21:20 : 02/05 81.3%
06:21:32 : 03/06 65.6%
06:21:48 : 04/07 50.0%
06:22:01 : 04/08 63.7%
06:22:15 : 05/09 50.0%
06:22:24 : 05/10 62.3%
06:23:15 : 06/11 50.0%
06:23:27 : 07/12 38.7%
06:23:36 : 08/13 29.1%
06:23:49 : 09/14 21.2%
06:24:02 : 10/15 15.1%
06:24:10 : 11/16 10.5%
06:24:20 : 12/17 7.2%
06:24:27 : 13/18 4.8%
06:24:35 : 14/19 3.2%
06:24:40 : 15/20 2.1%
06:24:46 : 16/21 1.3%
06:24:56 : 17/22 0.8%
06:25:04 : 18/23 0.5%
06:25:13 : 19/24 0.3%
06:25:25 : 20/25 0.2%
06:25:32 : 21/26 0.1%
06:25:38 : 22/27 0.1%
06:25:45 : 23/28 0.0%
06:25:51 : 24/29 0.0%
06:25:58 : 25/30 0.0%
06:26:24 : Test finished.

----------
Total: 25/30 (0.0%)

0.0% chance of guessing.

Satisfied yet?

I am a trained listener. Even though I don't have the high frequency hearing I had when I was younger, my ability to find artifacts in the rest of the spectrum is very good because a) I know how to conduct such tests and b) know what to listen for.

Hi Amir, that is remarkable, I have tried to do a not so accurate test situation and scored very ordinarily. To use a Monty Python sketch , You have cute earrings, or to put it more accurately Acute Hearing

 

[Piere]

Gee, we are below -130dB level here! What are we talking about, concerning audibility?

 

[sgaggy]

Sorry i write in Italy please translate.

 

[BDWoody]

Sorry i write in Italy please translate.

Welcome!
I got that one for you, but please translate before posting.

 

[sgaggy]

I misused it

 

[fpitas]

Gee, we are below -130dB level here! What are we talking about, concerning audibility?

Bragging rights. And embarrassingly enough, the monolithic op-amp wins.

 

[AdrianusG]

You guys are a bunch of idiots that you sit here and follow measurements to make your decisions on item the sparkos op amps sound absolutely amazing I don't care what your measurements say.

Whoever started this channel it's a complete scam and a racket that you got people hanging on measurements instead of listening to the item.

I put these amps inside my EVGA nu sound card the difference is absolutely nothing short of amazing I don't care what your charts and graphs measure what the ear hears the ear doesn't pick up on charts and graphs.

This is such a b******* freaking website.

Wow dude, perhaps next time try the "Decaf"

peace.