Op-amp Rolling Using Sparkos on Fosi V3 Mono

[xanalog]

I verify then trust.

I'd replace that awkward (and self-serving) last word with:

Earlier, I was ribbed for posting [#249] an answer from googleGemini about KT88/6550 tubes, which I had taken w/many grains of NaCl.

 

[Miser_Audioman]

Awesome at least I can leave the Sparkos be in my v3s. Not a big deal to take them apart but why futz with it. Thanks Amir for confirming that the swap at least does no harm! It sucks to spend $150 and reduce my bargain. But these amps sound fine, and with my Fosi x5 phono amp coming today, I still think overall Fosi has brought me tons of fun with minimal expenditure.

 

[Jimster480]

Awesome at least I can leave the Sparkos be in my v3s. Not a big deal to take them apart but why futz with it. Thanks Amir for confirming that the swap at least does no harm! It sucks to spend $150 and reduce my bargain. But these amps sound fine, and with my Fosi x5 phono amp coming today, I still think overall Fosi has brought me tons of fun with minimal expenditure.

I love my V3 Monoblocks!

 

[xanalog]

I love my V3 Monoblocks!

ummmm... is this a mono-gamous affair?
[sorry, I couldn't help myself!]

 

[Jimster480]

ummmm... is this a mono-gamous affair?
[sorry, I couldn't help myself!]

sooomethiiiiiing like that ;D

 

[NeLey169]

I tried changing the opamp on the fosi za3 and fosi zd3, they actually have a little difference but it's not significant at all, I found a pair of burson v5i-d opamps for $47, I replaced them for the Fosi zd3, and the stock opamp of the ZD3 is LME49720, I replaced them for the fosi za3..

My feeling with the zd3 + v5i-d: the mid is pushed up a little, the bass is a little deeper or more, just that but I don't find it better than the LME49720, it's different like the 2 musical and studio modes on my old Edifier MR4 pair.

LME49720 replaced with Fosi Za3 instead of NE5532 sounded too bright for my ears, after more than 1 hour of listening, I took it off and reinstalled NE5532 because I couldn't stand it anymore..

In the end, it cost about $50 to test, maybe I will take the V5i-d off to sell it again because I think buying an external preamp is much more valuable than buying an opamp.

 

[Jimster480]

I tried changing the opamp on the fosi za3 and fosi zd3, they actually have a little difference but it's not significant at all, I found a pair of burson v5i-d opamps for $47, I replaced them for the Fosi zd3, and the stock opamp of the ZD3 is LME49720, I replaced them for the fosi za3..

My feeling with the zd3 + v5i-d: the mid is pushed up a little, the bass is a little deeper or more, just that but I don't find it better than the LME49720, it's different like the 2 musical and studio modes on my old Edifier MR4 pair.

LME49720 replaced with Fosi Za3 instead of NE5532 sounded too bright for my ears, after more than 1 hour of listening, I took it off and reinstalled NE5532 because I couldn't stand it anymore..

In the end, it cost about $50 to test, maybe I will take the V5i-d off to sell it again because I think buying an external preamp is much more valuable than buying an opamp.

I would say it would make more sense to buy an external Preamp for sure.

 

[Cbdb2]

AI is mostly useless for these types of tasks. It just makes things up as it goes along and half the stuff that it tells you is just incorrect. It's like asking a 12 year old for the answer to the question.

Or an audiophool.

 

[Cbdb2]

Not nearly as much as, say, FETs, where a 5:1 variation in transconductance and 3:1 in pinchoff voltage are the norm. For example, in my phono preamp (no overall feedback), the largest effect of tube swap is in the second gain stage, and the worst tube clocked in at about 0.05% second harmonic, which I seriously doubt is audible. In my power amp, which uses EL84, changing from one brand to another barely budged the distortion needle.

Worn out tubes are a different story, but I don't classify that as "rolling." Ditto swapping pin compatible but vastly different tube types (e.g., ECC83 for ECC82). That's not really rolling, it's breaking.

Would you expect more differences between tubes in an amp designed to be overdriven for a lot of distortion, ie guitar amps?

 

[SIY]

Would you expect more differences between tubes in an amp designed to be overdriven for a lot of distortion, ie guitar amps?

I would guess yes, but I lack direct experience; I've only built two or three instrument amps, mostly I use solid state for my playing. I'd be looking at what Merlin Blencowe (who is quite expert at tube instrument amps) has to say.

 

[KSTR]

Would you expect more differences between tubes in an amp designed to be overdriven for a lot of distortion, ie guitar amps?

IME, in a guitar amp the tubes run under conditions that expose even minute parameter differences. Preamp stages, notably the input stage, often run open-loop (full gain) at AC and with only a bit of degenerating local feedback at DC ("self bias").

That means the DC operating point is not well defined which affects clipping behavior and you run the them into starvation and grid current from rather high source impedances. And running open-loop doesn't exactly stabilize the gain

All in all it is very uncontrolled what exactly happens when you approach saturation and real clipping. And the open-loop operation is very prone to impact the upper treble from the effective input capacitance (which is "Millered" and of course non-linear when outside the linear range).

The sensitivity of overdriven guitar amps to tube selection is mostly not a tube parameter variance problem, it's a circuit design issue.

 

[hifimacianer]

I just tried muse02 op-amps in my V3 monos.
To test the differences in sound, I just did it in one of the monos. The other one still has the stock op-amps.

My system is a WiiM Ultra , connected to a SMSL PO100pro (USB) to a Fosi ZD3 (via Coax). The V3 are connected with the balanced XLR from the ZD3.
Loudspeakers are Wharfedale Linton 85.

I set the WiiM to mono output, and used the Balance slider to switch between left and right channel.

And I have to say, I relly heard a difference!
With the muse02 the voices are more present and smoother. They seperate better from the rest of the music.
The higher frequencies are a bit softer than with the stock op-amps. I didn't hear a difference in the lower frequencies.

In exaggerated terms: with the stock op-amps it sounds like the singer is standing in an empty room with hardfloor,
while with the muse02 it sounds like you are in a cozy Jazz-Club with thick sofas and curtains. Just more relaxing and with more presence in the voice.

I also changed the V3 from left to right, to check if it's related to the position of the loudspeakers in the room.
Now the more relaxing sound came from the other speaker.

So it has to be the muse02.
I also let my wife decide wich side she prefers (she didn't knew where the muse02 was and how it is suppose to sound).
She also found the V3 with the muse more pleasant.

What's the takeaway?
There may be a difference in the gain between the two op-amps, what results in slightly different volumes.
But the overall sound impression was SO different, that I don't think thats relevant.

Well, then there may be more what affects the sound than pure measurements.
Maybe things that can't be measured...

I always think about LEDs. Could you see from the measurements in wich color the LED is shining?

 

[solderdude]

Well, then there may be more what affects the sound than pure measurements.
Maybe things that can't be measured...

That must be it.... but ...
Were the speakers positioned next to each other ?
Were the speakers level matched within 0.1dB ?
Did you also do the same with the amps swapped on the speakers ?
Can you make a recording. ... even using your phone ?

 

[Buckeye Amps]

Could you see from the measurements in wich color the LED is shining?

Yes. Very precisely. Well past what a human can discern with just their naked eyes.

 

[antcollinet]

Well, then there may be more what affects the sound than pure measurements.
Maybe things that can't be measured...

What do you think those magical unmeasureable things are? How do you think the desgner of the amp gets them into the amp, if he can't measure them? How does he even know he needs to: who specifies that they should be there? And how is it specified? Feature 3 - a little pinch of pixie dust?

More to the point - have you done a properly controlled (level matched) and BLIND test with the only thing varying being the op apm. Oh, and using the same speaker - because two different speakers - especially if not occupying the same space will more than likely sound different.

Because if you haven't, your uncontrolled listening impressions are - bluntly put - scientifically worthless.

 

[NeLey169]

I changed the opamp of fosi Za3 from NE5532 to OPA1612, strangely the background noise when installing OPA1612 is louder than NE5532.

I thought OPA1612 is the opamp with the best parameters and cheap price (I bought 2 pairs for 8$), but the background noise is louder

 

[pma]

I changed the opamp of fosi Za3 from NE5532 to OPA1612, strangely the background noise when installing OPA1612 is louder than NE5532.

I thought OPA1612 is the opamp with the best parameters and cheap price (I bought 2 pairs for 8$), but the background noise is louder

Did you check the amplifier for stability (after op-amp replacement) and did you measure noise and distortion?? I can hardly imagine bigger nonsense then if someone without measuring equipment and without knowledge equipment recklessly changes op-amps in the amplifier.

 

[NeLey169]

Did you check the amplifier for stability (after op-amp replacement) and did you measure noise and distortion?? I can hardly imagine bigger nonsense then if someone without measuring equipment and without knowledge equipment recklessly changes op-amps in the amplifier.

no, i just changed the opamp and heard the noise was louder than the stock opamp, that's it, i tried changing other opamp like v5i-d and the noise was higher than the NE5532.

 

[antcollinet]

no, i just changed the opamp and heard the noise was louder than the stock opamp, that's it, i tried changing other opamp like v5i-d and the noise was higher than the NE5532.

Have you not seen all the threads, all the tests (INCLUDING THE ONE YOU ARE REPLYING TO**) , and all the information on this site telling you that swapping op amps is a mugs game.

The circuit will be designed specifically for the op amp chosen by the designer. Without that specific tailored design, you are quite likely not going to get the benefits of the op amp specifications. You are certainly not going to get it by swapping at random without understanding the design choices of the engineer. Swapping op amps never (as far as I have ever seen) audibly improved the sound at the output of an audio device. At best it will make no difference. At worst it will make things oscillate.

**Sorry for letting my frustration show, but this is exasperating. There are 15 pages in this thread alone.

 

[wwenze]

I changed the opamp of fosi Za3 from NE5532 to OPA1612, strangely the background noise when installing OPA1612 is louder than NE5532.

I thought OPA1612 is the opamp with the best parameters and cheap price (I bought 2 pairs for 8$), but the background noise is louder

no, i just changed the opamp and heard the noise was louder than the stock opamp, that's it, i tried changing other opamp like v5i-d and the noise was higher than the NE5532.

Ah, I see where the problem is.

Does your background noise also happen to have color?