Emotiva XPR-1 1kwatt Mono Amplifier Review

[gene]

^^^
The Parasound Halo A51 does not have locking XLR connectors. I thought that was odd too.


On other sites, there are measurements that include two simultaneous tones, 60Hz and 7KHz.
There was a dramatic increase in ringing and artifacts that were clearly greater than the single tone tests.

I like this type of test because it might be a bit more revealing of the real world performance.
I am hypothesizing, but, while these artifacts are at a lower level often -50DB, is it not possible that if there was signal at those levels then the added information would be added to that signal.
Once added, then the distortion may be audible.
Is this not a possible explanation for why some amps are less fatiguing than others?

- Rich

I agree, I prefer locking connectors. I designed audio equipment for the military so I like to have things as rugged and secure as possible...hence why I love HDMI

RE: Distortion
I don't really see the need to do multi-tone testing like that, especially into a loudspeaker load. I do spot check various frequencies via FFT but show only 1kHz since its industry standard. There isn't much power/musical content at 20kHz and if there is ringing or slew related issues at those frequencies, it would show up with the full bandwidth Max power sweeps I do.

 

[Steve81]

RE: Distortion
I don't really see the need to do multi-tone testing like that, especially into a loudspeaker load.

FWIW the only reason I've ever see it performed is to check intermodulation distortion, which generally isn't a significant issue in modern amplifiers (at least I've not seen any measured that perform particularly poorly in this regard). Of course when present, it's my understanding that IMD is much more deleterious to sound than THD.

 

[jinjuku]

So you really believe they connect securely enough?....
At least it was enough to raise Gene's consideration

I'm still not convinced on this topic!

I've never had an issue.

 

[RichB]

RE: Distortion
I don't really see the need to do multi-tone testing like that, especially into a loudspeaker load. I do spot check various frequencies via FFT but show only 1kHz since its industry standard. There isn't much power/musical content at 20kHz and if there is ringing or slew related issues at those frequencies, it would show up with the full bandwidth Max power sweeps I do.

I found these results interesting even though the measurements are not completely comparable:

View attachment 11870

These are not into a speaker load but they indicate that artifacts are produced in the audible frequencies.
So the hypothesis is that when music is reproduced additional ringing that may be low level added to the signal may result in audible fatigue or other reviewer and user observations.

- Rich

 

[AcuDefTechGuy]

^^^
The Parasound Halo A51 does not have locking XLR connectors. I thought that was odd too.

So it is single-ended (instead of fully balanced) and non-locking XLR (instead of locking XLR).

Cost savings, I guess?

 

[slipperybidness]

If it's buzzing on its own with nothing connected but your speaker leads and power, then there is either something wrong with the amp or the ground in your outlet. Does the power meter stay illuminated the whole time as if there is something playing on it?

Try a diff outlet connected from a different circuit in your panel.

Otherwise, call Emotiva. It's not acceptable performance and if you are having a real issue with their product, I am sure they will help you.

I wouldn't recommend a "cheater plug" for long-term use, but they can be useful in determining whether or not the problem is a ground loop.

You are defeating a safety feature when you use a cheater, so proceed at your own risk.

 

[slipperybidness]

Bad wiring in your house; sounds like mine. All the receivers I have don't make a peep but every power amplifier I tried make my speakers buzz like a tesla coil even with nothing connected to them except speaker wire.

I'm not sure what the difference is between receivers and power amplifiers but some sort of circuitry must be present to clear out the noise that isn't used in power amplifiers is my guess, since the video circuitry is very vulnerable while power amps are inherently simple devices.

I would guess that your receivers may be 2 prong cords and the amps 3 prong cords?

 

[RichB]

So it is single-ended (instead of fully balanced) and non-locking XLR (instead of locking XLR).

Cost savings, I guess?

It costs something to encase the transformer in epoxy and it reduced transformer hum in my environment
For me, that was worth the money.

- Rich

 

[panteragstk]

I would guess that your receivers may be 2 prong cords and the amps 3 prong cords?

I'm willing to be you are correct. That would explain it.

 

[internetmin]

Oh geez thanks now i don't feel so bad. Yea my receiver is completely quiet also. The amp sounds amazing accept for buzzing.

If the buzzing is coming from the amp itself and you've unplugged everything else, you may have an issue called DC offset that is typically caused by dimmers and microwave ovens in the home. The second cause of DC offset can be a slightly loose transformer in the chassis. There's nothing you can do electrically in your home to correct the DC offset issue. However, you can address it at the amp itself by getting the Emotiva CMX-2 Line Restoration and Common Mode Filter System: CMX-2 Link. You can view the product details here. This unit specifically addresses the issue of DC offset. The key here will be to plug in the amp with nothing else--including the speakers--connected to it. If the amp buzzes, then you likely have DC offset. For $99 it's a simple fix. There are other home-grown solutions available online, but this unit from Emotiva is relatively inexpensive and will do the job.

 

[internetmin]

If the buzzing is coming from the amp itself and you've unplugged everything else, you may have an issue called DC offset that is typically caused by dimmers and microwave ovens in the home. The second cause of DC offset can be a slightly loose transformer in the chassis. There's nothing you can do electrically in your home to correct the DC offset issue. However, you can address it at the amp itself by getting the Emotiva CMX-2 Line Restoration and Common Mode Filter System: CMX-2 Link. You can view the product details here. This unit specifically addresses the issue of DC offset. The key here will be to plug in the amp with nothing else--including the speakers--connected to it. If the amp buzzes, then you likely have DC offset. For $99 it's a simple fix. There are other home-grown solutions available online, but this unit from Emotiva is relatively inexpensive and will do the job.

As a follow-up, it's also fairly common for a receiver to be fine and a power amp to exhibit DC offset. Generally, the larger the transformer the more sensitive it may be with DC offset in a home. Receivers, even if rated to larger power levels, don't normally have as large a transformer as an amp. It's the transformer that buzzes.

 

[internetmin]

So it is single-ended (instead of fully balanced) and non-locking XLR (instead of locking XLR).

Cost savings, I guess?

It's funny you should mention that. I've tried to purchase all balanced equipment over the years and some of it has been locking and some has not had a locking mechanism. My general observation is that most of the consumer-oriented audiophile equipment tends to be non-locking.

 

[internetmin]

I found these results interesting even though the measurements are not completely comparable:

View attachment 11869View attachment 11870

These are not into a speaker load but they indicate that artifacts are produced in the audible frequencies.
So the hypothesis is that when music is reproduced additional ringing that may be low level added to the signal may result in audible fatigue or other reviewer and user observations.

- Rich

To the uneducated guy that I am, does the Lexicon measure better in this example? It seems to me that even though there is greater amplitude, a good chunk of the measurements are between -100 and -120. The Parasound exhibits less amplitude fluctuation, but sits higher on the DB axis.

 

[RichB]

To the uneducated guy that I am, does the Lexicon measure better in this example? It seems to me that even though there is greater amplitude, a good chunk of the measurements are between -100 and -120. The Parasound exhibits less amplitude fluctuation, but sits higher on the DB axis.

Two non-amp experts talking

Yes, it looks that way to me too.
I am not trying the pick the better amp but the question I have is if there are artifacts from any amp at -65 DB at about 200HZ (as in the Lexicon example), what happens if there is music at the frequency at -10?
Do the artifacts then get added to the signal?

If that is the case, then could be much greater amplifier coloring of music than is found in test patterns and this could be one reason that amplifiers can sound different even though they both measure very well.

It would also mean that amps are not nearly as accurate when amplifying music as they are amplifying test tones.

- Rich

 

[Steve81]

To the uneducated guy that I am, does the Lexicon measure better in this example? It seems to me that even though there is greater amplitude, a good chunk of the measurements are between -100 and -120. The Parasound exhibits less amplitude fluctuation, but sits higher on the DB axis.

I wouldn't qualify myself an expert but if I'm interpreting your statement correctly, the difference you're referring to appears to be in the noise floor of the two amplifiers. Given that the bench tests appear to be done by different reviewers years apart under different conditions, I wouldn't spend a lot of time worrying about it.

 

[gene]

Multi-tone Distortion Testing

You have to be careful when doing multi-tone distortion tests. The tests referenced from Secrets don't appear to be done with much consistency (test frequencies are different, scales are different, etc). I am thinking about revamping our FFT test to incorporate Multi-tone tests similar to what is done in the Telephone world via IEEE standards. There is a mathematical formula for doing this to get meaningful results. I will try to dedicate some time over the summer on this. 60Hz is the same Frequency of the power line for domestic 120V power, so it should be avoided.

 

[Steve81]

the question I have is if there are artifacts from any amp at -65 DB at about 200HZ (as in the Lexicon example), what happens if there is music at the frequency at -10?
Do the artifacts then get added to the signal?

Let's suppose for a second they do, and see what happens:

I'll call ref level 100dB because it's a convenient round number. Suppose you are playing a 200Hz tone at -10dB from ref, i.e. 90dB, and you've got a bit of distortion that creeps in that happens to be perfectly in phase at -65dB from ref, i.e. 35dB. What's the sum of 90dB + 35dB? For all practical purposes it doesn't move the scales.

That's of course no fun, so lets ramp up the distortion by a few orders of magnitude to 65dB, ie -35dB from ref and add that to our 90dB signal. Now you get a result: ~90.5dB.

Hope this helps.

 

[internetmin]

I wouldn't qualify myself an expert but if I'm interpreting your statement correctly, the difference you're referring to appears to be in the noise floor of the two amplifiers. Given that the bench tests appear to be done by different reviewers years apart under different conditions, I wouldn't spend a lot of time worrying about it.

Ah, didn't realize it was different reviewers. So it's not an Apples to Apples test. Thanks for that clarification!

 

[RichB]

You have to be careful when doing multi-tone distortion tests. The tests referenced from Secrets don't appear to be done with much consistency (test frequencies are different, scales are different, etc). I am thinking about revamping our FFT test to incorporate Multi-tone tests similar to what is done in the Telephone world via IEEE standards. There is a mathematical formula for doing this to get meaningful results. I will try to dedicate some time over the summer on this. 60Hz is the same Frequency of the power line for domestic 120V power, so it should be avoided.

Ah, didn't realize it was different reviewers. So it's not an Apples to Apples test. Thanks for that clarification!

The different tones and scales makes it difficult to compare but I do not think that makes them invalid.

For AH, that sounds like an interesting measurement. Of course, if performed in a standardized manner, results *should not* change from reviewer to reviewer. Some sites like HomeTheaterMag have a measurement staff that *should* be reviewer independent.

- Rich

 

[RichB]

Let's suppose for a second they do, and see what happens:

I'll call ref level 100dB because it's a convenient round number. Suppose you are playing a 200Hz tone at -10dB from ref, i.e. 90dB, and you've got a bit of distortion that creeps in that happens to be perfectly in phase at -65dB from ref, i.e. 35dB. What's the sum of 90dB + 35dB? For all practical purposes it doesn't move the scales.

That's of course no fun, so lets ramp up the distortion by a few orders of magnitude to 65dB, ie -35dB from ref and add that to our 90dB signal. Now you get a result: ~90.5dB.

Hope this helps.

I am not sure I am following you. Doesn't the sum of 90 DB + 35 DB = 125 DB?

- Rich