Blind test: opamp rolling in the Pearl 3 phonostage

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Mark Johnson

Mark Johnson

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Joined 2011
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In Pearl 3 post #1,396 I offered to send out pairs of opamps, to perform blind listening tests in the Pearl 3 phonostage:
Mark Johnson said:
If anyone wants to listen to their Pearl 3 with "rolling opamps" in a single blind test, shoot me a PM.

I'll send you some dual opamps whose part numbers have been sanded off and painted over with different colored paint. You won't know which is which and I won't tell you the ones that are, or are not, in your batch. Maybe I'll send you four sets of identical dual-741's (perhaps RC4558 etc) in different colored paints, because I am a sadistic baxter. Maybe I'll send you some bleeding edge Telleurium-Gallium-Phosphide military grade opamps on SOIC-to-DIP carriers, mixed in with TL072 and LM358. Who knows. Maybe the best of the best of TI and Analog Devices and Cirrus Logic, all mixed together. If you're willing to possibly make a fool of yourself by "hearing" superior performance from 60 year old dual opamps, ... let's party.

You and I will split the cost of the parts and the adapters and the postage, until you post a message here containing your listening evaluations. Then I'll send you the other half of the money --- and your net cost (in money, not reputation) will be zero.

Do I have a protocol which guarantees there is no lying or changing-your-mind about what color is what opamp? Yes. And it is so obvious you should be ashamed of yourself if you even think to ask.

Let's party.
Click to expand...

Then in Pearl 3 post #1,765 I showed three photos (attached below) of the anonymized opamps.

Next, in post #1,817 I presented the (encrypted) table of opamp_part_numbers and their corresponding serial_numbers on the sticky labels.

And now, today, in Pearl 3 post #2,732 , the first listening evaluations of the blind test opamp rolling experiment, have been posted. I am thrilled that duyAudio member @Lvandoorn created a panel of four different listeners: himself, spouse, audiophile friend #1, audiophile friend #2.
Lvandoorn said:
Rolling the opamps in the blind....

I received 7 pair of opamps to test in my Pearl3. They are coded
A318, A170, A785 A848 , A957, A093 and A539. I added to those anonomous opamps the JRC opamps I received with the kit and a pair of Muses02 I allready had.
Mainly tested at my place with a heavily damped Lenco L75 with an Ortofon MC30 cartridge. Preamp is the balanced Iron pre from Zenmod, the 6-24 crossover from this Nelson guy, two modded ACA’s for mid and midbass, and a Reckhorn amp for the Slotted OB bass. Speakers are mahogony horns with JBL drivers from 480hz, Volt 12 inch on the SLOB baffle (60 to 480 hz) and Augie 15 inch for the slot loaded part. These tests I did together with my wife, no electronicly interested molecule in her body but she loves listening to music.
Secondly I did the comparison with a vintage Stax electrostatic headphone, very nice sound but compromised in volume. Tests done on my own.
And to verify that I was not completely imagining things I brought my Pearl3 to a diy friend with a very nice diy system ( I think) with a Lenco using a Denon DL-103 and all good Pass stuff. Together with a third audio fanatic (a semi-professional musician) I asked them to judge the 4 best opamps from my evaluation. While I did my best not to show my order of preference they agreed with me. Relieve!
So far so good, agreement between the four people involved was almost 100%.
Now to the disappointing part, of course it is all very system and record dependent, still very subjective but worse is that I find it very hard to describe the differences.
Records used were Friday Night in San Francisco (Al DiMeola Paco de Lucia John McLaughlin) Famous Blue Rain Coat (Jennifer Warnes) Ben Webster meets Oscar Peterson, Sonny Rollins Colossus, Miles Davis Ascenseur pour lÉchafaud, Dire Straits Love over Gold and J.J. Cale Troubadour.
To my ears the positives and negatives of the opamps did not change a lot with the different music. After the first round of listening the top two opamps were found and it required quite a bit of discipline to go back and listen to all of them, again and again….
I tried to bring some system in my judgment by focusing on low (clear bass notes, bass drum impact) mid (voices, guitar, sax) and high frequency (cymbal, high notes on instruments), speed and life feel. And tried to give an overall score, from 1 to 10.

I will tell my verdict of them in my/our order of preference with special aspects they did well or not so well in my opinion

JRC overall score 7. Nice sound, could easily live with those if I had not heard the others. Lowest score of all on life feel and involvement. Bit bland sound
A957 overall 7.2. no special remarks to make
A848 7.4 Did pretty well in overall sound and different frequency areas but no ‘speed’ or life feel.
A318 7,5 Weaker on bass to our ears, did well on speed and attack
A170 7,7 Nice, did well on almost all aspects but lacked life feel and involvement
A785 7,8 Really nice, Of the top 4 it lacked however most in speed and life feel
A093 7,8 Very hard to tell apart for me from A785. Just a little bit better in dynamics I feel
Muses02 8 Good, could be a permanent choice in my chain. Did everything really well in comparison to the rest of the field
A539 8, 2 In this shootout the best, more involving and more life feel, really excellent in speed and attack.

I am really looking forward to see the overall results of this (mostly) blind test and to see to what extent I agree and disagree with my fellow testers. And of course to find out where I completely was fooled by my ears...

And of course many thanks for this fun project to Mark

Leo
Click to expand...

Watch this thread for further developments including a timeline of how and when the decryption key will be posted, allowing everyone to see which opamp part# corresponds to serial number A785, A093, etc. I'm having a medical procedure at the hospital tomorrow, so there may be a few days of delay...

Best regards to all, -- Mark Johnson
 

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runclesid

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Joined 2004
Started out with LME49720 op-amps. Seems to work well in the Pearl3, no hiss or noise, or RFI. Tuning the bias of U1, went with 620R for R27. 620R is what I had in hand for a Vishay Dale. Current ended up around 4mA on U1.

Initially there was something strange, it was putting out -2.17 vdc on the output with R27 at 220R on both channels. Not sure why that happened to them unless there was something interacting with the LME7920. Going to 620R dialed it all in and very close to the voltages shared on a previous post earlier in this thread.

I dropped gain a little bit by using the spare 220R (from R27) and paralleled the R22 (220R) for the gain. Running 110 ohms helped with the 4mV cartridge output. There is no apparent loss in fidelity.

I am very impressed with the sound stage and dynamics especially with percussion. The bass is nice with control.

Edit - add U1 current
 
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Mark Johnson

Mark Johnson

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Dual opamp "A539"with score 8.2 in the @Lvandoorn shootout, sounded the best to his listening panel. It was more involving and had more life feel, really excellent in speed and attack. A539's datasheet is dated February 1971. Like all of the seven anonymized opamps, it was housed in an 8-SOIC package mounted on a SOIC-to-DIP header. More info in a few days.
 
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jitter

jitter

Member
Joined 2004
Lvandoorn said:
I was not 100% serious about the vintage bit ... I would like it however to have some Philips dna, my dad worked there and I started the diy thing with their EE experimenter kit as a 10 year old
Click to expand...

If I were to hazard an educated guess, then it would be the MC1458/1558, simply because the TI-datasheet I found on it carries the February 1971 date.
 
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