Switched Amps. Where Could The Difference Be Coming From?

[Trdat]

I switched the amp for 3 way bookshelf speaker from my long time serving NC252MP to the NC502MP because I wanted more power and because the NC252MP clipps now and again when I push it hard on my Marantz AVR.

To be honest, I was dissapointed. No doubt, no difference in the general sonic nature but the bass wasn't as clean. Now, I don't want to get subjective here, but to try and figure out where the difference might be coming from, my question relates to the idea around the fact that the power from the more powerful NC502MP in the 4ohms 313 watts(more from the spec sheet 400watts) might be providing too much wattage to the low bass driver(3. 6 ohms at 120hz) and around those frequencies and causing the bass not to be as presice? There was a thread on damping factor and how an amp provides power according to the impedance and there was a mention that differences in amplifiers could relate to how the amplifier provides power at different frequencies and although it something that we shouldn't worry about I am wondering if this is what happened here...?

There can't possibly be audible differences between these two amps.

The only other thing I can think of is that my Audiolense DSP was tuned in for the NC252MP. Can the DSP make such a difference even when two amps are transperant? I mean, can the DSP take in consideration the damping factor and when amps switch there can be a very small percieved difference?

 

[Deleted member 21114]

Can you measure the difference with a measurement mic and REW? If not, any answers are going to be speculative.

 

[SIY]

Can you measure the difference with a measurement mic and REW? If not, any answers are going to be speculative.

Better yet, measure the difference electrically at the speaker terminals. MUCH more accurate than using a mic and trying to capture this stuff against the noisy background of a room and all of the uncertainties of rooms and transducers.

 

[Deleted member 21114]

Better yet, measure the difference electrically at the speaker terminals. MUCH more accurate than using a mic and trying to capture this stuff against the noisy background of a room and all of the uncertainties of rooms and transducers.

If OP produces comprehensive electrical measurements I will buy you a drink SIY.

 

[antcollinet]

I switched the amp for 3 way bookshelf speaker from my long time serving NC252MP to the NC502MP because I wanted more power and because the NC252MP clipps now and again when I push it hard on my Marantz AVR.

To be honest, I was dissapointed. No doubt, no difference in the general sonic nature but the bass wasn't as clean. Now, I don't want to get subjective here, but to try and figure out where the difference might be coming from, my question relates to the idea around the fact that the power from the more powerful NC502MP in the 4ohms 313 watts(more from the spec sheet 400watts) might be providing too much wattage to the low bass driver(3. 6 ohms at 120hz) and around those frequencies and causing the bass not to be as presice? There was a thread on damping factor and how an amp provides power according to the impedance and there was a mention that differences in amplifiers could relate to how the amplifier provides power at different frequencies and although it something that we shouldn't worry about I am wondering if this is what happened here...?

There can't possibly be audible differences between these two amps.

The only other thing I can think of is that my Audiolense DSP was tuned in for the NC252MP. Can the DSP make such a difference even when two amps are transperant? I mean, can the DSP take in consideration the damping factor and when amps switch there can be a very small percieved difference?

Damping factor is not going to be it. Both amps have damping factor way higher than needed for it not to be an issue.

Are you doing the comparison of the sound level matched (accurately using a voltmeter at the speaker terminals) and within the power limits of the smaller amp?

Are you with the new amp pushing it hard volume wise? If so, you may well be driving the speakers into distortion with the higher power available. What is the recommended amp power - or power handling rating for your speakers?


Of course we also may be into the realm of cognitive biases where you are (for example) hearing a difference just because you are listening for it, and not because it is there.

 

[Trdat]

Can you measure the difference with a measurement mic and REW? If not, any answers are going to be speculative.

I agree everything will be speculative.

I am under impression that REW isn't going to show such minor differences perhaps maybe the decay graph in the frequency region we are after? But we can get those differences by moving the mic quarter inch to the left or right so how accurate can REW be when it comes to understanding how the amp responds to the speakers impedance curve. Maybe there is a way....

 

[Trdat]

Better yet, measure the difference electrically at the speaker terminals. MUCH more accurate than using a mic and trying to capture this stuff against the noisy background of a room and all of the uncertainties of rooms and transducers.

Seems like a better method but what does this give me exactly?

 

[Trdat]

Damping factor is not going to be it. Both amps have damping factor way higher than needed for it not to be an issue.

Are you doing the comparison of the sound level matched (accurately using a voltmeter at the speaker terminals) and within the power limits of the smaller amp?

Unfortunately not. And I am not claiming any major differences, they essentially did sound the same just the bass was off...

Are you with the new amp pushing it hard volume wise? If so, you may well be driving the speakers into distortion with the higher power available. What is the recommended amp power - or power handling rating for your speakers?

This was my initial impression. I honestly think that adding a few more db to the speakers just either added distortion or was playing the woofer too loud. Although at lower volumes the problem was still there. Again, I happy with the NC252MP, this is just trying to understand and connect perceived differencess with scientific look at what it might be. But without me measuring I suppose we can't establish anything.

Of course we also may be into the realm of cognitive biases where you are hearing a difference just because you are listening for it, and not because it is there.

This possibillity is also there, and I am the first one to put my hands up of believing in something that doesn't exist but because i did notice sraight away the bass wasn't as refined, I am going to go with your concept that the distortion just either from the Marantz AVR which starts distortion from around 4 volts might have something to do with it(not sure if this is audible. Or the speaker itself just couldn't handle that power and distortion and that it was from the drivers itself. I just wanted to rule out damping factor....

I think the real way would be is to measure to get SINAD right? But would a REW measurements distortion tell us enough about the distortion characteristics to know if its from teh speaker itself?

 

[voodooless]

Are you doing the comparison of the sound level matched (accurately using a voltmeter at the speaker terminals

Gain of both amps should be the same unless something was customized. Check the manual for confirmation. If the gain is not the same and you use any kind of volume dependent processing, that may very well explain any perceived difference.

I am under impression that REW isn't going to show such minor differences perhaps maybe the decay graph in the frequency region we are after?

If you can hear it, you measure it easily. An amp will not influence decay.

But we can get those differences by moving the mic quarter inch to the left or right so how accurate can REW be when it comes to understanding how the amp responds to the speakers impedance curve. Maybe there is a way....

That why a measurement at the speaker terminals is much better.

 

[Sokel]

If talking solely about lows a small mic change won't make a big difference,why don't you try it if you have both amps in hand?
Just measure 20-300Hz.
Set the same gain,level and everything and do it,better spend 5 minutes than speculate.

That if you can't measure them electrically and at least you will rule out if the new one is faulty.

 

[antcollinet]

Unfortunately not. And I am not claiming any major differences, they essentially did sound the same just the bass was off...

So I am 99.9% certain that these amps will sound the same IF they are playing under the same conditions.

That means exactly the same volume (Even just half a dB - or even less - can make one amp sound better) and this is where relying on gain spec might not work, I'd guess that device to device tolerance might exceed 0.5dB).

AND playing within amp limits. That means if the lower power amp is clipping due to not having enough power to play at your selected comparison volume then all bets are off. Another reason why electrically measuring the level is useful - you can ensure the smaller amp isn't trying too hard.

But to be honest, I suspect the real reason is you are hearing differences that don't actually exist. We've all been there (I know I have) anxiously wanting to be certain our new investment has been worth the money. Or just being interested in how the new kit sounds different. This expectation sets up all sorts of biases that cause us to hear differences that are not in the sound waves. I'd suggest - forget about comparing for a few weeks. Relax and listen to the music. Your perception of different sound will probably fade.

 

[MaxwellsEq]

Two completely identical amplifiers will sound different if you have a 0.1V or greater difference in signal levels when undertaking the comparison.

 

[boxerfan88]

Try a REW sweep (20-1k) with both amps (microphone at the exact same spot for both sweeps) and compare the decay & waterfall. Does the bass region decay differently?
Also check the distortion charts ... are they very similar or there are significant differences?

Post the mdat file if possible. I'm curious.

 

[antcollinet]

Try a REW sweep (20-1k) with both amps (microphone at the exact same spot for both sweeps) and compare the decay & waterfall. Does the bass region decay differently?
Also check the distortion charts ... are they very similar or there are significant differences?

Post the mdat file if possible. I'm curious.

Decay is a function of speaker and room - not amp. Amps do not have a decay.

 

[Trdat]

But to be honest, I suspect the real reason is you are hearing differences that don't actually exist. We've all been there (I know I have) anxiously wanting to be certain our new investment has been worth the money. Or just being interested in how the new kit sounds different. This expectation sets up all sorts of biases that cause us to hear differences that are not in the sound waves. I'd suggest - forget about comparing for a few weeks. Relax and listen to the music. Your perception of different sound will probably fade.

The funny thing is that my bias would have been towards the NC502MP because I wanted more power and was hoping more power would be less distortion with the NC502 but I think more power through the drivers translated to distortion to the drivers. Hence why the NC252 was the better sounding amp just before clipping which coud well indeed mean that the clipping was at that point of speaker driver distortion. IN saying that, the biases could be coming from the comparison to my horn/15 inch and the fact that I want my 3 way to go louder and this attempt might have just given too much power to the speakers.

 

[Trdat]

Decay is a function of speaker and room - not amp. Amps do not have a decay.

Yes, my apologies for understanding it incorrectly I thought perhaps more bass at a certain frequency might produce some type of indication in REW but that is essentially distortion in this case right?

 

[Trdat]

Two completely identical amplifiers will sound different if you have a 0.1V or greater difference in signal levels when undertaking the comparison.

Yes, when we say difference any difference? Or the amp that has the extra .1 Volt sounds better due to it being louder?

In this case the louder one sounded worse.

 

[antcollinet]

The funny thing is that my bias would have been towards the NC502MP

Don't think of "bias" in this context as being like a "prejudice". Think of it as a "shift" (like biasing a transistor). The shift can go in any direction.

They are subconscious and may have nothing to do with our conscious expectations.

 

[boxerfan88]

Decay is a function of speaker and room - not amp. Amps do not have a decay.

Yes, agreed. Therefore both charts should look similar. (which is what I am expecting)

If it does not look similar, means something else is going on that is triggered by amp change.

 

[MaxwellsEq]

Yes, when we say difference any difference? Or the amp that has the extra .1 Volt sounds better due to it being louder?

In this case the louder one sounded worse.

There's no rule. They will sound different. Which one you prefer is subjective and therefore impossible to predict.

And this has nothing to do which is more powerful. You might have the 1000W amplifier 0.1V quieter than the 10W amplifier.