The Opamp thread

[musikaladin]

...here my XD-05 withh a V5i....

 

[afshin]

Hi
opa1612 is a Bipolar-Input  opamp and burson v5i is a Fet-input Discrete  and opa2604 is a Fet-input ...
Fet input opamp usually  Input impedance is much higher. It can sound so much alike.
Thanks for any comments.
 
afshin

 

[pelopidas]

I'm not sure input impedance has much effect on sound. When you look at the data sheet of an opamp (take the lme 49990 for example) you will see that it is rated to drive 600 ohms. That means it can drive from infinity down to 600 ohms without deteriorating the distortion values of the opamp. Once you start going lower than 600ohms the distortion rises as does the difficulty of the load. The lower the ohms (impedence) the more current it takes to drive and opamps are not really made to drive current. High ohms means the opamp is just swinging voltage and not pushing current.
So the design of an opamp is to have, ideally, infinite input impedence and zero output impedence. This is great for driving another opamp or a dedicated current follower as a final buffer.
This is THE weakness of the O2 design. The I/V stage amplifies the signal and sends it to a NJM4556 opamp. The designer NwAvGuy, liked that the design had low output impedence but the problem is that the 4556 is rated down to 150ohms. Many headphones are as low as 16 ohms. Even the higher rated 300 or 600 ohm headphones are dynamic and sometimes swing lower than 150 ohms. That little opamp can't ever sound great driving 32 ohm headphones.
But it could sound just fine driving an amp.
Pardon my rambling. I was just trying to say that I don't think it is the input impedance that makes opamps sound similar or different. It is the circuitry as a whole of the little chip that gives it its sound profile.

 

[afshin]

hi
Thanks for your feedback ...
Over the past 4 years my research on testing the op Amp. Without considering the effect of oscilloscope was triggered only by considering the effect of hearing sound.
A lot of op amp was tested. With various materials such as Bi-polar and Fet and Difet.
Di-fet input impedance is higher than the Fet. opa627 that is Difet.
Fets with Bi-polars was very different sound altogether. The gap between the dark background and musical instruments in Fets and
More dynamics in Bi- Polars.
By studying the datasheet:
Fets = better sound stage
Fets designed for enhanced AC performance = More and deeper bass and greater sound stage.
Fets designed for enhanced DC performance = Less bass and more detail.
Fets designed for Hi speed = More dynamics
Bi-polar = More dynamics and not deep stage . Dynamic vocal  is very good But theStage is missing.
 In between...
The opa2604, opa604 in single . The input stage is two feet.It also has Distortion Rejection Circuitry .Recommended for I/V stage in datasheet . I have found the most balance opamp In every respect for I/V stage.I think using a film capacitor 1uf for bypass PSU Enough.
In the datasheet clearly refers to the use of 1uf tantalum capacitors. But I say film cap has better audio character. Ceramic cap character failing for audio purposes.Their effects are piezoelectric effect. Even NPO and COG !But a little better.
Of course, other issues such as capacitors and audio chain is important.
The result of my thoughts. I thank any comments

 
 
thanks.afshin
.

 

[pelopidas]

Sounds like you have put some real effort into this. Very nice!
I would love to know which opamps gave you which results. This sounds like a fun experiment to follow.
In general I would agree with no ceramics and no tantalums as a good rule of thumb (with exceptions). I really noticed this with a snubber circuit. The films were much more dynamic than ceramics. I was really amazed that a snubber circuit could have a flavor of its own.
I used to believe that the "audio path" and the rest of the circuit were two seperate things but experience has shown that everything leaves a mark on the sound. Something else I have learned is that film caps are great in the role of input capacitors but actually not good as power supply bypasses. The effect is a squeezing of the soundstage.
I think, if you haven't tried them already, that you will like the discreet opamps like the V5 SS. None of the opamps I have ever tested come anywhere close to the dynamics, details and the soundstage of those.
Happy listening and keep us updated!

 

[FritzS]

I prefer FET - OPA626 and Supreme Sound Opamp V5 in my headphone amp

 

[afshin]

hi
 
opa626 designed for ADC drivers   =    Analoge  to  Digaital 
---------  designed for DAC drivers   =    Digital      to  Analoge
!!!

 

[Lohb]

  I prefer FET - OPA626 and Supreme Sound Opamp V5 in my headphone amp

What are the characteristics of FET vs other stuff that you like so much ?

 

[abartels]

Hi Guys,
 
I got a SS V5i-D from Burson and tested it last week. First attempt did fail, not sure what I did wrong, but it definitely was NOT due to a faulty opamp.
Probably I didn't fit it adequate in it's socket.....
 
I used an I2S only, heavily modded  DIY AK4495SEQ based board, fed with seperate toroidals for digital and analog portion of dac board.
The dac board is modified with Nichicon FG's for VREF, psu stages, and buffer for opamp. Most of them located underneath the pcb.
Further I connected an Ian Canada's FIFO II + Isolator board + DualXO II board to the I2S input. Clocks used at DualXO II: NDK NZ2520SD
FIFO II fed by separate toroidal and 0.8uV low noise psu, DualXO II fed by separate R-Core and 0.8uV low noise psu.
Opamp used was an LME49720HA milspec version.
 
Ian Canada's FIFO II is fed by a RaspBerry Pi 2 board using piCorePlayer (latest 3.0 version) which connects to LMS server.
 
This combination worked very, very well for me. Thought this combination was at it's best, until I changed LME49720HA for the Burson SS V5i !!!
 
Before final reviewing I did burn-in the V5i for 150 hours. I just did a short listening session when connecting the first time, cold out of the box, just for fun.
As expected it sounded a little dull in my opinion, too much bass output and no controll, veiled soundstage and not very detailed. But, since I was aware of it's needed burn-in time I wasn't afraid at all
 
The Burson V5i really is a big step-up in sound quality in comparison to LME49720HA. It's much livier, big, wide and deep soundstage, very natural sounding!
Vocal timbre, and timbre in common is very musical, bass control is huge, never heard this kind of deep powerful and tight bass control from an opamp! (it's almost like swearing when calling this V5i an opamp.....)
 
I must say this opamp really comes VERY close to discrete amplifier stages, sounding very life like, not hiding anything, tons of details but still very musical!
My verdict: If you can't go the discrete route, this surely is the way to go. I wouldn't be amazed if this Burson V5i is the BEST opamp available for bufferstage!!! And, I am very sure I heard discrete solutions in the past
which performed much LESS than this SS V5i. Well done Burson!!!
 
Next step: Comparing the V5i to Burson's flagship V5 

 
Some pics:
 

 

 

 
 
Regards,
 
Alex

 

[zilch0md]

 
Burson V5i
 
[snip]

 
Thanks for this. I really enjoy reading your assessments. You are so "credible."  
 
No rush, but if you ever get a chance to try the SS3602, I'd love to see how you think it compares to the V5 SS. (I, too, am a big fan of how the V5 SS sounds.)
 
Mike

 

[abartels]

Thanks for the rep. Mike 

 
 
 
Yesterday I incorporated FIFO II-Isolator-DualXO II in my "MonsterDAC". This dac will be used to test SS V5, will compare with SS V5i and a Chinese discrete opamp (OP01) 
 

 
This is the "MonsterDAC" 

 

 
 

  Alex

 

[Mad Max]

What™

 

[pelopidas]

Hey Mike

I want to test the Sparkos as well. Discreet vs discreet. This is much more fun than lme49720 vs opa827. Look how far this hobby has come.
I recently went a month without the V5 SS just testing out different chip opamps again for various reasons. Chips are so bad in comparison. I felt a non-stop urge to keep swapping and trying different combinations. So after wandering in the sonic desert for a month I have the V5 SS back in and I think what I missed the most is
1: the 3D holographic soundstage. You can almost see where each sound is placed and it feels like it has a definable shape.
2: the decay. I had almost forgotten how involving this aspect of the music is.
3: the detail. Every whisper, creaking chair in the recording room and every note and harmony.
I can't do chip opamps anymore. With the V5 SS back in I am listening to music again that I listened to over the last month just to hear it right. I'm listening to music again and not thinking about my Dac and my amp and opamps.

So I guess that means that at this point only a Sparkos would be interesting to play with.
For all other new readers. Consider the incremental cost of buying little chip opamps over and over looking for the " heavenly, angels singing," sound. It's not to be found in a chip. Go discreet. As with anything that is important and where quality matters "Buy once, cry once" ... You save money in the long run.

 

[zilch0md]

  What™

 
Exactly!  LOL

 

[zilch0md]

Hey Mike

I want to test the Sparkos as well. Discreet vs discreet. This is much more fun than lme49720 vs opa827. Look how far this hobby has come.
I recently went a month without the V5 SS just testing out different chip opamps again for various reasons. Chips are so bad in comparison. I felt a non-stop urge to keep swapping and trying different combinations. So after wandering in the sonic desert for a month I have the V5 SS back in and I think what I missed the most is
1: the 3D holographic soundstage. You can almost see where each sound is placed and it feels like it has a definable shape.
2: the decay. I had almost forgotten how involving this aspect of the music is.
3: the detail. Every whisper, creaking chair in the recording room and every note and harmony.
I can't do chip opamps anymore. With the V5 SS back in I am listening to music again that I listened to over the last month just to hear it right. I'm listening to music again and not thinking about my Dac and my amp and opamps.

So I guess that means that at this point only a Sparkos would be interesting to play with.
For all other new readers. Consider the incremental cost of buying little chip opamps over and over looking for the " heavenly, angels singing," sound. It's not to be found in a chip. Go discreet. As with anything that is important and where quality matters "Buy once, cry once" ... You save money in the long run.

 
Great advice!  
 
These "expensive" discrete op-amps are very affordable upgrades when you consider what they can do for "mid-fi" quality amps - as with the iBasso PB2, for example.  
 
I would nevertheless caution people to tackle the weakest link in the chain, first - and that usually involves spending a lot more money than you would on a pair of these "expensive" op-amps - which are best appreciated when nothing else is in the way, so to speak. They would not be able to make any detectable contribution with most $200 headphones, for example.
 
I've written this elsewhere and at the risk of losing credibility with people who don't believe great sound can be had without spending a lot of money, but for several weeks now, I've come to prefer the sound of my Sparkos SS3602-equipped PB2 with dummy buffers to any other amp I own, including my $1200 Metrum Aurix.  And, sad but true, I prefer the ES9018K2M DAC of my iBasso HA-2, fed with a Sony NWZ-A17 via a USB emulation cable (for FLAC files on microSD cards) -or- with an Apple Touch 6 (for Tidal HiFi via WiFi), to anything I can do with my Metrum Octave MkII (or with my the DAC and amp sections of the Oppo HA-1) - and that's for either the HD800 or PM-1 or my new favorite headphone by far - the DT880 600, modded with locking mini-XLR connectors for more power via balanced output from the twin SS3602's in the PB2.
 
And, not just to support your enthusiasm for the Burson V5, I'll add that they were only barely knocked off their perch by the Sparkos - for my tastes, my gear, my ears. The V5 sound is a little smoother in the treble - and is also more laid back, less dynamic - again, that's with the HD800 and the "Poorman's HD800" (the DT880 600 - when supplied with plenty of power.)
 
By the way, I really like the improvement made by using the SILMIC caps on DIP extenders - for the Burson V5 - as you had recommended, way back when):
 
Elna SILMIC II 35v 10uF caps soldered for dual op-amps
 
 
 

 

 
 
But don't try using these caps, wired as shown, with the Sparkos SS3602 duals - at least not with the iBasso PB2.  When I turned on the amp, I got a loud pop followed by no audio (but no harm done, apparently).  When I wrote Sparkos about it, he couldn't offer an explanation. I even repeated the "experiment" after confirming (with the caps removed) that no damage had been done to anything. I was certain that I had Pin 1 oriented correctly.  So, proceed at your own risk if you want to try adding caps across Pins 4 and 8 on the Sparkos SS3602.  They sound so awesome without adding caps - it wasn't as if I was trying to fix a problem.
 
Mike