Sparkos SS3602 Opamp Rolling In Fosi P4

[solderdude]

Do you understand that there's an output stage between the op-amp and the output?

Noise data were presented. Did you miss those? Determined by the output stage, of course.

This is a pre-amp... unlike the power amps with TPA3255 this one is op-amp only.
Still, given the small differences measured I can't help but wonder if the little SMD opamp is always in circuit (even when tone control is defeated).
The replaceable op-amp may well only be the output stage.

Which can also be measured:

• DC offset / DC level at the output

The frequency response suggests it is not DC coupled. Could be at the input, could be at the output, could be in the feedback loop.

• common mode rejection rate of the input (imported noise by cabling)

It is RCA in...

• noise floor especially at very low frequencies (< 100Hz)

Below 100Hz the hearing is VERY insensitive.

• input resistance: possible impacts on level, frequency response and dc offset when sourcing from a source with high output resistance (100+ Ohm)

Could be tested,

• output performance on difficult loads (600 Ohm) and/or on high output levels (power supply headroom, slew rate, max power)

How many amplifiers (it will be connected to) will have such unusual low input impedance, let alone difficult ones ?

• power consumption and as consequence heating based performance degradations (eg. drift)

Amir could have made a FLIR shot after an hour or so.

 

[antcollinet]

Do you understand that there's an output stage between the op-amp and the output?

Noise data were presented. Did you miss those? Determined by the output stage, of course.

Not to mention....

CMRR and input impedance - close to 100% dependent on the circuit, not the opamp.
Power consumption of the preamp will be mainly depending on the circuit overall. The op amps will consist of only a part of that.
Noise is already in the measurement in the OP.

 

[Count Dacula]

Just because you can do something, doesn't mean you should.

 

[DavidM1]

Just because you can do something, doesn't mean you should.

Lol. This is not an attitude that made anyone rich selling hifi accessories.

Now, where did I leave my doorstop electron stabiliser?

 

[gamerpaddy]

there are kinds of people out there that just resist being educated or believe common sense is a bad thing.
these are the kind of people im not having a issue selling a 1000$ power cord to

 

[olds1959special]

I would like to roll the op-amp, is it hard to disassemble and get back together? It looks like I don't need to remove the front knobs from this picture.

 

[SIY]

I would like to roll the op-amp, is it hard to disassemble and get back together? It looks like I don't need to remove the front knobs from this picture.View attachment 458974

The SMD ones will almost assuredly end up causing you to destroy the unit. The socketed one is more likely to merely degrade the performance without smoke.

 

[olds1959special]

The SMD ones will almost assuredly end up causing you to destroy the unit. The socketed one is more likely to merely degrade the performance without smoke.

It’s socketed. There are horror stories about stripped screws needing a drill to remove and broken volume knobs. I’m not understanding why I need to remove the volume knobs looking this picture, but I’ll see. I’ve taken apart my Fosi ZA3 many times and never had a problem, so I’m not sure why it would be so hard to deal with the P4. It looks like just a few screws in the back, remove the switches, and pull off the case. No need to touch the knobs. Am I wrong?

 

[amirm]

I would like to roll the op-amp, is it hard to disassemble and get back together? It looks like I don't need to remove the front knobs from this picture.View attachment 458974

It is is not hard to take apart but a pain to put back together -- definitely not like the other Fosi product that advertises opamp rolling. The challenge is that rear switch. You can unscrew it and pull the case and back out. But how do you align it back to assemble? You can take out the connector cable but then inserting it while the case is over the switch is hard. Eventually I managed to do it but I don't recommend it.

 

[mlsstl]

On the issue of subjective listening, I'd like to recommend this book: "A Mind of Its Own - How Your Brain Distorts and Deceives" by Dr. Cordelia Fine. It is a great read and explains in great detail how our brains can fool us. The titles of the nine chapters are pretty self-explanatory:
1. The Vain Brain
2. The Emotional Brain
3. The Immoral Brain
4. The Deluded Brain
5. The Pigheaded Brain
6. The Secretive Brain
7. The Weak-willed Brain
8. The Bigoted Brain
9. The Vulnerable Brain

After reading this, you'll not be surprised by any of the subjective stuff that you read about audio equipment. The only silly thing to me is that so many of these people think they are somehow exempt from this human condition. That said, I'm not overly concerned about the issue. Our day-to-day listening is routinely done in sighted conditions with full awareness of the makes and models of the equipment involved. It is no surprise that the gear's physical appearance, pride of ownership, investment cost and all the advertising and reviews we've read are circulating in our brains as we listen. The net result is that if it makes that person happy, great!

 

[olds1959special]

It is is not hard to take apart but a pain to put back together -- definitely not like the other Fosi product that advertises opamp rolling. The challenge is that rear switch. You can unscrew it and pull the case and back out. But how do you align it back to assemble? You can take out the connector cable but then inserting it while the case is over the switch is hard. Eventually I managed to do it but I don't recommend it.

I decided to leave it alone, especially since it performs slightly worse with the SS3602.

I’m a little curious why one person claimed it improved the sound, but not enough to deal with the headache of modifying it.

 

[antcollinet]

I decided to leave it alone, especially since it performs slightly worse with the SS3602.

I’m a little curious why one person claimed it improved the sound, but not enough to deal with the headache of modifying it.

Probably because they carried out uncontrolled listening comparisons.

 

[MaxwellsEq]

I’m a little curious why one person claimed it improved the sound

Did this one person measure before and after the swap and then publish data demonstrating how the change had measurably improved the device? I suspect not

 

[olds1959special]

I wonder if the appeal of the Sparkos SS3602 is the feeling of enhanced treble and dynamics that I noticed when I played around with different op-amps? Is it actually distortion that creates this effect? The way tubes do? No matter what, the Fosi P4 sounds amazing without changing the op-amp (or the PSU.)

 

[SIY]

I wonder if the appeal of the Sparkos SS3602 is the feeling of enhanced treble and dynamics that I noticed when I played around with different op-amps? Is it actually distortion that creates this effect?

Vastly unlikely. It would take a LOT of distortion to have that effect and what you'd notice first is how fuzzy and rough the signal sounds.

 

[olds1959special]

I was bored and curious so I went ahead and opened up the Fosi P4 to put in the Sparkos SS3602. I don't agree with Amir that it's hard to do. With the tools in a small electronics screwdriver kit I was able to detach and re-attach the switch easily and didn't have to take off the front cover. What confused me was a little bit of red tape over the switch which made it hard to pull off and I didn't realize I needed to remove the tape first. Fortunately I didn't destroy it trying to get it off. I put it back together and played music but didn't realize I hadn't selected the right device in my player, so I thought it wasn't working. So I took it apart, checked everything, and put it back together. It was pretty easy the second time.

The sound change? First thing I noticed was more bass presence, and maybe I'm noticing a little more forwardness in the treble. The changes are subtle.

 

[solderdude]

An op-amp is technically incapable of affecting bass presence and forwardness.
You can be 100% sure that what you perceived is placebo and that's why it is subtle as well.
You hear differences because you know that you changed the op-amp.
That's the reason why all other op-amp swappers also hear differences.

 

[olds1959special]

I tried MUSE02 and it sounds a bit softer. The bass of the Sparkos seemed a little much, I think I'll leave it like this for now.

 

[solderdude]

Muses 02 swap measurements.

As mentioned bass cannot possibly be affected by op-amps.
There is no 'mechanism' for that to happen.
The only 'mechanism' that is capable of doing that is the brain that 'knows' something changed.

That effect is exactly what the whole audiophile electronics business relies on.
That and substantial (deliberate) modifications of the signal.
The latter can also be shown in well performed blind tests, the former is never provable with properly controlled blind tests.

This is part of the appeal of 'playing around with the mystical side of everything audio'.

 

[olds1959special]

As mentioned bass cannot possibly be affected by op-amps.
There is no 'mechanism' for that to happen.
The only 'mechanism' that is capable of doing that is the brain that 'knows' something changed.

That effect is exactly what the whole audiophile electronics business relies on.
That and substantial (deliberate) modifications of the signal.
The latter can also be shown in well performed blind tests, the former is never provable with properly controlled blind tests.

This is part of the appeal of 'playing around with the mystical side of everything audio'.

I'm not saying you're wrong, but I heard a difference, so I guess I must be hearing things that are not there?

I'm not saying it got better with changing the op amps.