Saturday 14 December 2019

MEASUREMENTS: Emotiva XPA-1L (Gen 1) Class AB Balanced Monoblock

Let's continue measuring some amplifiers I have here at home. Today, we're going to get a bit more serious with fidelity into the "audiophile" level. Of course I'm using the term "audiophile" here for fun since audiophilia often does not equate with high-fidelity; but who else uses monoblock amps at home except for audiophiles!?

Here's a single 35lb Emotiva XPA-1L "Gen 1" monoblock which I bought back in 2013, a few months after it was released. Far from the most expensive monoblock amplifier out there, costing a "mere" MSRP US$699 each:

This is one of two I have in use as my reference amplifier for many years now. There's not much to see on the rear - speaker outputs, both RCA and XLR inputs (toggle switch to select), IEC power connector, 12V in/out trigger (can daisy chain a few devices) and main power switch. In the front, we have the large round Emotiva switch to turn on from sleep mode, a single LED that turns red when running diagnostics or if there's a fault, and blue as above when fully on. Notice that there is a switch just above the etched serial number to set it to either "standard" Class AB mode or the special Class A high bias mode which is a selling point for this amp that we'll of course talk about. When the switch is toggled to "A", it operates at Class A for up to the first 35W into 8Ω.

Over the years, I have seen a couple of (p)reviews from Audioholics and The Poor Audiophile, but have not seen any independent measurements of the output quality.

From late 2014 until they discontinued this model (not sure when), Emotiva also made the "Gen 2" model which cosmetically looked slightly different with black instead of silver side trims. I believe internally they also made some changes which were more about cost-cutting than affecting the sound quality.

Remember that running in Class A makes the amplifier significantly more power hungry, hotter due to reduced efficiency with most of the energy dissipated as heat (~25% Class A efficiency vs. ~50% for Class AB). Consumers however have been told that Class A sounds "better" due to higher linearity without crossover distortion. We'll try to quantify that with this device.

This amplifier incorporates 90,000µF of capacitance and has a large 450VA toroidal transformer inside for the linear power supply. A few months ago, I replaced an issue I had with one of the XLR connectors (darn XLR locking tab got stuck) and took a picture of the guts; power supply portion on the left, amplifier board on the right:

As you can see, there's a lot of "stuff" in there to make up those 35lbs of a discreet, balanced, Class AB amplifier including a fair amount of metal as heatsink; there is no fan. The weight is not just thick metal fascia in an otherwise empty case. :-) Having said this, there's of course nothing wrong with higher quality enclosures.

The company rates this device as capable of delivering 250W into an 8Ω load and a clean double of 500W into 4Ω (conservative THD <0.1%, presumably 1kHz signal). Since I'll be measuring with a 300W 4Ω resistor, I'll definitely have to leave a few 100 watts on the table in my measurements!

I connected the amplifier with standard 18G IEC AC cabling to the wall socket. General measurement technique as described in my "MOAR" post a few weeks back. Balanced cabling used for testing.

I. Basic Amplifier Characteristics

Amplifier Gain was measured as +35.1dB through the RCA input and 6dB lower at +29.1dB with the balanced XLR input. The manual states +29dB gain which must be referring to the balanced input.

Amplifier Damping into 4Ω is better than the previous amplifiers measured on this blog:

Across the audible spectrum, the damping factor is at least 40x with an average of >80x across the 7 frequencies examined. Note that by the time one reaches a level of 100x+, slight variation on the voltage meter will result in huge swings (I've been using the oscilloscope to measure average RMS voltage). The high damping in the bass range will provide excellent control of woofers. Notice the drop after 1kHz. With this amount of damping, we should see excellent control of frequency response even with low-impedance speakers.

Here is the Frequency Response of the amplifier comparing a 4Ω load and the Sony SS-H1600 speaker I've been using as a comparator - range on the Y axis of this graph is only 4dB:

As expected, with the high damping factor, we see quite a smooth Sony bookshelf speaker curve. Notice that this amplifier tends to roll-off the high end (-2dB at 20kHz for 4Ω load) a bit more than the Onkyo receiver a couple weeks back. There's also a -0.2dB roll-off in the bass as well by 20Hz.

Here's what the Phase Response looks like compared to the frequency response across 4Ω:

Still reasonable looking phase response I think from 20Hz to 48kHz. We're seeing a -12° at 20kHz corresponding with the frequency roll-off; as usual, we need to consider the audibility of phase shifts and human hearing in order to gauge importance of this...

II. Single-Tone Harmonic Distortion and Noise

Let's look at Harmonic Distortion vs. Frequency at various power output levels - 2V (1W), 6.32V (10W), and 20V (100W) using a frequency sweep:

Not bad. Looks like THD remains controlled across the audible spectrum. Notice that as we get to the higher power levels, the odd harmonics become more prominent - for example, we can see the 3rd harmonic taking over as the highest level harmonic for most of the frequency spectrum by 20V/100W.

Here are some THD(+N) graphs of 1kHz fundamental ranging from 16mW to 250W output:

As I mentioned above, this is a high power amplifier and indeed, at 31.6V/250W the amplifier is still producing output with better than -85dB/0.0056% THD+N. While not shown here, for those who might be curious, the 5W into 4Ω SINAD is 85dB.

So far, all of this is with the Class AB setting... What if we flip the switch into "Class A" mode as well for the THD+N vs. Voltage curve?

As you can see, I've overlaid a yellow curve (Class A) over the orange line (Class AB). We actually don't know with the Class AB setting at what point it transitions away from pure Class A - perhaps at most a handful of watts?

There's really little difference in THD+N whether it's in Class AB or the high bias Class A mode. Though small, somewhere around 6Vrms (~9W into 4Ω) seems to be the most notable THD+N difference.

Remember though, this is THD+N and the noise component can be getting in the way of the difference between the two settings; what if we just had a look at the harmonics themselves? Here are some Class AB vs. Class A mode THD+N spectra:

On the left, we see the 1kHz tone and spectrum at 5, 10, and 25W when the switch is set to "AB" mode and on the right is the "A" setting. Immediately I think we can appreciate that indeed harmonics are lower at 5W and 10W particularly but not much difference by 25W into 4Ω.

Despite this overall lowering of harmonics in Class A mode, which by the way is primarily a reduced 2nd harmonic, there is a price to pay. Notice how the 60Hz power-line hum and its harmonics have worsened at the "Class A" setting. Class A mode puts a significant demand on the power supply and this can be appreciated with the Kill-A-Watt meter - in Class AB mode, power draw is ~100W when idle while Class A mode sucks up much more power, about 220W when idle!

The bottom line is that "Class A" mode, despite claims which to some extent can be verified objectively as showing "improved" distortion results, creates other issues. In fact, we could argue that the power-related 60Hz harmonics take away any benefits one might hear. Furthermore, it's mainly just the 2nd order harmonic that is reduce while the 3rd order harmonic appears almost untouched.

In general, over the years I have not heard of any owners of this amp claim the ability to hear a large difference between AB and A mode. As far as I can tell, the "first watt" was always Class A already. Over the years of listening to this amp, I've been suspicious that this is what I'd find as I never really heard a difference either... Nice to be able to get the results and report on this after all these years; Class AB mode is IMO excellent already.

III. Multi-Tone Testing: Intermodulation Distortion and Triple-Tone TD+N

Here's the panel of SMPTE, CCIF/ITU-R, and "Linkwitz" 2-tone intermodulation signals at 2V into 4Ω:

And here are the same IMD signals, 10V into 4Ω:

With a 2V signal, across the board with the IMD tones, we're seeing a low -80 to -86dB distortion and with 10V, the distortion is higher, ranging from -68 to -80dB. As a point of comparison, remember that the Onkyo TX-NR1009 "WRAT" AV receiver scored -60 to -80dB at 2V for these three IMD signals.

Here's the result from the "transient intermodulation" (TIM) distortion test looking at sidebands forming around a 12kHz sine tone situated within a 1kHz square wave. We can see that by 10V output level, there are a couple of sidebands sitting above -100dB. There's a bit more distortion here than what I found with the Onkyo receiver a few weeks back even at 14V. Comparatively, the Onkyo had more power-related spuriae down in the noise floor at 2V however.

As I discussed before, I'm just not convinced that the TIM result necessarily correlates to audible distortion given how extreme these test tones are compared to real music! Nonetheless this still is an interesting measurement to look at as a proxy for an amplifier's slew rate and potential "accuracy" of transients.

Finally, for the Triple-Tone Distortion and Noise measurement used in my AMOAR scoring system (in the Conclusion section), here's the TD+N at 2V and 10V into 4Ω:

2V TD+N result of -80.6dB. The TD+N increases to -76dB at 10V output.

As I demonstrated above in Section II, turning the switch over to "Class A" does have an effect with lowering THD. Here's the difference between "Class AB" and "Class A" for the TD+N at 6.32V into 4Ω:

An improvement in TD+N of -2dB for the Class A setting with lower distortion although there again seems to be a bit more low-level power supply related noise.

IV. Square Wave and Wideband Noise

Here's my "non-aliasing" 24/384, 1kHz square wave at 2V through the oscilloscope:

Remember this is a monoblock, so only one channel. The square waveform looks good with no gross asymmetries and clean leading edges. As a "bonus", here's what a 2V, 10kHz square wave looks like with this amp, again, originating as a 24/384 "non-aliasing" digital signal:

With a Class AB amplifier like this, one does not expect to see much ultrasonic noise unlike "switching" Class D amps where we often can find 400-500kHz content: 

Yup, we can easily see the double peaks at 5kHz and 93kHz (notice the roll-off of the 93kHz vs. 5kHz). Otherwise, nice and clean all the way up to 1.5MHz. Nothing to see here folks...

V. Impressions and Conclusions

Without further ado, here's my summary 4Ω "AMOAR" Composite Score:
Updated... Made a mistake with the text colors and frequency response previously and shifted up to show more of the roll-off. Also, because I used the Douk Audio passive pre-amp to control volume, slight droop in bass and treble compensation added.
The XPA-1L runs completely silently without a fan which is a must for audiophiles IMO. Output noise level is low and I only hear a mild hiss when listening with my ears to the main Paradigm Reference Signature S8 speaker connected to this amp and with volume turned up. It's capable of high average damping factor (ie. low output impedance) of at least 40x into a 4Ω load across the 7 frequencies I measured within the audible spectrum. Damping factor is especially high in the lower frequencies <2kHz which is good (better woofer control). The Triple-Tone Distortion Factor at 2V output result of -81dB is excellent as well, beating out the Onkyo TX-NR1009 with a result of -73dB distortion (and of course the very inexpensive Yeeco Class D of only -51dB). With a Power Factor >32V or >250W while keeping THD+N <0.1%/-60dB, this device has plenty of power which will satisfy the vast majority of home audiophiles. Certainly more than I need. Remember, this amplifier is rated at 500W into 4Ω.

If there is one acoustic characteristic I would have liked to be more "ideal", it would be the frequency response. Notice that this amplifier starts rolling off the high frequencies around 2kHz and by 20kHz, we're down at -2dB with a 4Ω load. While not ideal, this should still not be a problem in real-life listening and might even be desirable especially if you have tweeters that are a bit harsh above 10kHz or to tame metallic tweeters with resonance peaks. On this blog over the years, I've already seen this amp's tendency to roll off the treble years ago when I compared this amplifier against the Vitus Audio SS-010 in 2016; note that for those measurements, I had used an 8Ω power resistor.

The Class AB/A front switch is an example of an interesting feature that looks good for advertising material. It certainly differentiates this amplifier from others even within the Emotiva lineup. In practice, the amplifier already is excellent in Class AB mode (mature solid state technology after all!) and the difference, while measurable, is small and as far as I am concerned, inaudible. The only noticeable difference is the inefficiency in Class A mode with a hotter-running amp and about twice the power draw when idle - great for this time of the year when the basement is cool and Class A mode can help serve to warm up the room :-). It's also worth reminding everyone that even with that Vitus Audio amplifier mentioned above, turning the amp to Class A mode also made a slight improvement in distortion level but just like with this amplifier, nothing significant and IMO inaudible.

Subjectively, as they say, beauty is in the eyes of the beholder. She's rather flat, squat, isn't adorned with the prettiest face, but her voice is beautiful and she can belt out the tunes when needed :-). This amplifier sounds great especially if you have potentially harsh speakers, I suspect. Plenty of "microdynamic" details on account of low distortion and lots of "slam" when you need the oomph to drive louder passages. I was certainly impressed when I first got them noticing that I was able to turn the volume up louder than usual and not feel fatigued compared to a Denon AV receiver I was using for a number of years before. If I had heard anything objectionable, I would have changed the amps out years ago.

The Emotiva XPA-1L is a competent "hi-fi" monoblock power amplifier. At US$700 x 2  MSRP for a stereo pair when first released, performance wise, it's a nice example of a good modern high-power solid state Class AB amplifier. While it may look utilitarian, I know that the performance is clearly superior to some more expensive "audiophile" boutique brands (like the Vitus Audio SS-010).


To end off, let's talk about brand names for a second. I am also very happy with the performance of my Emotiva XSP-1 preamp by the way, and I see no reason to doubt the subjective and objective sound quality especially of their higher tier products. Over the years, I have run into audiophiles who seem to have negative impressions about the Emotiva brand name despite never having heard the products or have an impression that these are just meant to be for home theater use. An amplifier is an amplifier regardless of what the advertised target audience might be. The lower prices and good value certainly places Emotiva in the "budget brand" category and hence the lack of "snob value" will not appeal to certain magazines and writers more affected by the non-utilitarian aspects of luxury products than actual sound quality. I think it's important to consider the assumptions inherent among circles of traditional audiophile culture. There's nothing wrong with being discerning when one chooses a product, but it's important to consider if one is simply expressing undue discrimination without objective facts or a genuine attempt at unbiased subjective experience.

Inevitably, cultures change as younger participants enter the hobby and I think the relative value of brand names will shift with the different perspectives of the changing participants with their take on technology and economic sensibilities.

Not seeing much going on in the audiophile world this week; just the usual "best of" lists and more consumerism. End-of-year and people preparing to go off on holidays soon, I suppose.

A friend showed me some cool "trailer" music from Two Steps From Hell the other day, a production team that has created many interesting clips that one may have heard especially in the background of movie trailers but unaware of the source. Anyhow, it has been fun listening to stuff on Invincible (2010), and Archangel (2011) this past week. Recommended for a listen if you find this kind of music exciting, majestic and "inspiring". That's of course interspersed with some Christmas albums playing around the house like the gleeful Lea Michele's Christmas In The City (2019) which my wife likes and my pick - A Blackheart Christmas - depending on mood and company ;-).

Hope you're enjoying the month and the music!


  1. I think you need to read what BYRTT say about the Phase graph.

    - maty -

    1. Thanks Maty and BYRTT,
      Did a recalculation with minimum phase and reuploaded the graph... I trust this looks more like it now! Also updated the Onkyo one which wasn't as drastic a change.

    2. Recalcuation with minimum phase? It seems all you have to do is set the ADI's own filters (AD and DA) to linear phase ones. Maybe (maybe) then perform some normalizing with REW to get a straight graph on zero. Please explain the 'recalcuation'.

    3. Hi Techland, looking into this and will update the phase graph further today. I fortuitously took a few readings and will discuss the findings...

    4. Alright guys, I hope 3rd time's a charm with that phase graph :-).

      Here's the situation. The sweep was done with linear phase from the AD and DA. I believe BYRTT on DIY Audio is right - the very first graph I posted where the phase was essentially 0° was off. With that high-end roll-off, the phase graph should have been around -20° down at 20kHz.

      REW's "Generate minimum phase" tab was able to create a more accurate phase graph but this recalculation of the impulse response misses out on the small amount of "excess phase" component in the measurement.

      Anyhow, what I realized was that I had forgotten to account for the "IR delay" with the measured phase response. Once this was done, we see the graph currently updated above; phase shift at 20kHz is -19°. Hope this is clear (and corrected now). :-)

    5. Grrr... One last tweak for accuracy. Because this is a monoblock amp, I used the Douk Audio passive preamp in the chain. This actually contributed to part of the frequency response droop and corresponding phase shift.

      Have compensated for this and updated graphs. The small amount of bass droop is less but the high frequency roll-off only slightly changed.

  2. It's interesting to finally see an amplifier with both Class A and AB capabilities measured; there have been few people who have put this to the test over the years and it's become "received wisdom" among the audiophiles that Class A is somehow magically better. While I have no doubt this amp is great in both modes, I agree - no one could tell the difference if they weren't able to see which position the switch is in. ;-)

    I'm a little surprised to see that so many modern amps have "droop" at both ends of the audio spectrum - and of course, any amps which have low damping factor will exhibit poor linearity at low frequencies with difficult speakers, adding to the problem. This will include many of the dreadful tube units which already lack sufficient clean power to drive a typical speaker. I'd rather have too much clean power instead of not enough - you don't need to use it all! The first watt is probably better too.

    The old presumption that "pro" and "home theater" equipment somehow doesn't hold up against "audiophile" equipment has been with us since the days before I started exploring audio in the 1960s. It's just another label to distinguish models from one another so that manufacturers can sell to different markets - except for the occasional added input jacks or DSP features which shouldn't affect sound quality anyway.

    As I've mentioned before, I replaced my old and very fine Dynaco 400s with a pair of new Crown XLS amps, primarily to reduce the size, weight and power consumption of my rack. The Crowns, despite being marketed as PA amplifiers, are outstanding and perhaps a little better at driving my inefficient speakers. There's also little to choose between them in terms of measurements.

    Christmas season around here is always the time to trot out all the fun stuff like Dr. Demento's compilations; but my favorite go-to album will always be the wonderful Vince Guaraldi's "A Charlie Brown Christmas".

    1. Thanks for the multiple points Greg,
      As far as I can tell, Class AB has reached a state of maturity that there's really no need for Class A based on "sound quality" reasons. A bad sounding amp is simply bad and one should not be making any excuses based on "class".

      Yup, more power available is good ;-). Watts are indeed cheap these days and so long as it's clean, I have no special fetish about flea-watt devices or esoteric rationale (like some who are strongly anti-feedback).

      When we look at the audiophile cottage industry, it's no surprise at all when we see devices that clearly perform poorly. One really wonders how much money some of these companies actually put toward actual engineering. With advancements these days, it's no surprise that on average, decent devices at decent prices will perform quite nicely. I think one only has to look at the DAC space to see all the $$$$$ devices that use old, poorly performing DAC chips or questionable stuff like noisy discreet R2R ladders to recognize the silliness of it all.

      Sure, some folks might like the sound of this stuff and write glowing reviews (or have subjective reviewers write glowing reviews for them!), but with the power of DSP, EQ, etc... Dirty sound can be had without such expense and with great levels of individual control.

      Those Crown XLS amps look amazing at very reasonable prices. I'm wondering, for example the XLS 1002 with 350W into 4-ohms, is the fan always on or does it only spin up during heavy use? Does it ever get distracting in a sound room with low SPL ambient noise level?

      Absolutely, Guaraldi's always awesome ;-).

    2. Just to be clear, I have the 1502 because it uses a separate ADC/DAC chip on the board to improve SNR over the 1002 and its integral DSP/ADC/DAC. And I got a great price on it. ;-) They are otherwise almost identical.

      I have tested it on the bench, with no other sources of noise in the room, and I can only barely tell when the fan is running with full power out of the amp (you'll probably never see that on music). Crown's cooling design is really efficient, and they do not turn on the fan until the heat sink exceeds 45C. From there it increases to full flow at 75C, which I have only seen when testing with a dummy load.

      With music playing at moderate levels, the fan is probably not even running; their temperature monitor shows about 42C pretty constantly. And if I turn it up, there's no way the fan could be heard over the music even with my ear to the ventilation grille. I feel confident in saying the fan shouldn't ever be a problem, especially if the amp is a few feet away from the listener.

      By contrast, my Dynacos had low-speed muffin fans and they were quiet but clearly audible when music was not playing. It was a little obtrusive; I can't hear the Crowns at all when not feeding music in. And I have three of them; the system is tri-amped. There's probably more noise from the computer's hard drive, and I can't hear it either. ;-)

    3. Don't know if you've seen Amir's review of a Crown XLS1502

      I've used four XLS1500s for several years now, fan noise I gave up trying to catch in the act...altho I suspect it has been louder at times, nothing noticeable from my listening position and barely a whisper when I've put my ear up against the amps...

      Thanks Greg for the explanation of the reason for the snr difference between the 1000/1002 and the rest of the lineup....

    4. Heh. Chris beat me to it. It does raise in interesting point. Lots of people really like their XLS150x's, yet it measures solidly meh.

      My own hypothesis is that most recorded material most people listen to (ie. popular -- not to be confused with "Pop") doesn't require 90+ dB of SINAD. 75-80 dB will sound fantastic.

      ... or maybe it's the subjective impression of knowing you scored an incredible deal. Hmmm, I've never seen that mentioned in the sighted listening debates. Seems legit now that I think about it. If one group of people can be positively impressed listening to crazy expensive kit, surely there is another group of people can be similarly positively impressed listening to crazy high price to performance kit. ;)

    5. The funny thing about the Crown XLS series is that 40 years ago they would have been hailed as super low distortion amps - way better than the then-current crop of solid state units. They really don't do too badly even today - I've been able to confirm that they run well under 0.1% distortion throughout the audio band at the highest music levels I play (20-50W peaks for my speakers; yes, they're inefficient) and their noise level is below -90 dB at the same output, barring some 60 Hz stuff which might be due to my test rig.

      Here's something I think many people just aren't aware of: when testing these amps, it's vital to have a filter between the output and the measuring system which eliminates the residual ultrasonic switching noise. Crown has a pretty serious filter on the output already, but there is definitely still some leaking through, visible on an oscilloscope. Even though it will never make it to the speaker drivers because of inductance in the cable and speakers themselves, it shows up on a wideband measurement system and will ruin any SINAD measurements. It doesn't take much added junk on the signal lines to push the baseline up from "very good" to "poor". From the measurements I've seen, it appears that some testers don't band-limit the signal and are seeing the ultrasonic "hash" as part of the results. In that case, the values can easily rise to -60 dB or so, depending on your test rig. That's only 20 mV on a 20V signal, even though outside the audio band.

      Again, the final test is always listening. I'm actually acutely sensitive to noise, and have been known to turn off my HVAC system when listening to music (don't tell the wife). Admittedly, my speakers aren't high efficiency but with the preamp gain literally at max and no signal, I can put my ear against the speaker and hear nothing. That's partly because I pay attention to gain staging, but also it's certain that the Crowns don't add anything to the noise. If I screw up the individual component gains, it is possible to get audible noise; most of it from my inline equalizer.

      Distortion is something we can't easily identify; but at comfortable volume levels, the system doesn't exhibit any listening fatigue or obvious strain. The speakers generate the vast majority of the distortion at those levels anyway; I've measured them as well and it rises into the 1-2% region when the amp is contributing less than 0.1% (peaks of over 90 dB at the listening position).

      So I'm pretty comfortable with the way the system performs, and subjectively it's very good sounding. If I were one of the subjectivist reviewers, I'd probably rave about how much better it sounds than it did before I bought the Crowns, but that's where impressions overpower the facts. ;-) The fact is, it's good enough that nothing intrudes on the music, and that's all I really care about!

    6. Wow. Great discussion about the Crown, fan noise, and switching noise!

      Nice to hear that the fans are off when not hot, and inaudible even when on, that will really help with those who might be a little worried.

      Speaking of SINAD and distortion significance. I'm in the process of cooking something up for 2020. Stay tuned :-). Indeed, as Greg noted, distortion from speakers are definitely a big deal compared to what we're measuring off the amplifiers themselves.

      As for switching noise and that, also, we'll talk more about this in 2020 with devices on the test bench!

    7. The one example I can think of for amp noise thru the speakers with the Crowns was a guy who had a treated room with very low noise floor (30dB area), and super high sensitivity horns (109-110dB). He also had noise issues with a Marantz pre-pro IIRC and ended up with Benchmark gear. I've not had any issues with that with a variety of speakers myself.

  3. Why the Emotiva has so many components while the Schiit Vidar has so few components.

    What are their design philosophies ?

    1. Many ways to skin a cat I suppose ;-).

      Might want to pose this to the Emotiva forum and see if the engineers there or if Schiit's guys able to discuss this!

  4. Hi

    on the Oplug Forum of Linkwitzlab there are some comments on Crown XLS1002. Measures not bad (-65dB THD+N) but not as good as ATI or Emotiva.

    The fans are mentioned as very noisy.

    My experience with a Marantz MM8003 (8 channel power amp) and Yamaha AVR XR-V2400 (7.1 Recevicer) is you hear the fans even 5 meters away.
    Conclusion: only no fan is silent fan.

    On the Marantz MM8003 I changed it for a ultra low noise fan, change mounting with silicon rubber gasket. Much better however you can still hear it!

    Either no fan or amps in an other room.

    1. Interesting, very different impression compared to gregdunn above. We might have to double check on the model numbers and such to see about those Crowns.

      Thankfully over the years with my Denon, Onkyo and Yamaha receivers, I've not had issues with fan noise. I've always enjoyed file-based music playback and I'm certainly glad that these days there is no longer a need for an actual computer in the room with the risk of fans...

      If at all possible, I agree, "Only no fan is silent fan" is a good one ;-).

  5. Not sure what they're doing to make the fans spin up so loudly - maybe they are seated right behind the amps at ear level playing loud subsonic EFX tracks. ;-) I just measured my room with nothing turned on (even the central heating was off) and I got about 40-45 dB A-weighted. Placing the measurement mic both in front of the Crown and behind it (within 2 inches of the fan) gave levels within a dB of the ambient level. C-weighted was a little higher for all three locations, but still not much different from each other; the spectrum was mostly very low frequencies (below 50 Hz or so). My listening position is about 6 feet from the amp rack.

    With my rather inefficient speakers playing at a comfortable level I can clearly hear when the central heating comes on (it measures about 65-70 dBA because I am next to the room where it is installed) but the Crown fans have never been audible even in the middle of the night when it's quietest. As I mentioned, the small variable speed fans on my Dynacos were always intrusive up to moderate volume levels where they were eventually masked by the music - but I think that was mostly because the fan noise was conducted through the chassis and it had a large 60 Hz component.

    I play a fair amount of quieter folk and less complex orchestral/ensemble music too, and again, I can't hear the fans - ever. Pushing 50W or so (x3 amplifiers) into my speakers on some louder rock and classical selections masks any sound they might be making; even during quieter sections while the amps are still warm and the fans might be running they're not noticeable.

    Arch, if you buy one of these and can't deal with the fans, I'll buy it from you and figure out somewhere to put it to use. ;-)

    1. LOL. Okay Greg. Will let you know if I buy one and the fan noise sux. :-)

  6. Thanks!

    I recently bought Emotiva amps, for an active setup : A-300 and A-100. I'm happy to see that they are producing honest products.

    1. Have not tried them myself, but looks like capable products Yan.

      Hope you're enjoying them...

  7. The spec says 20-20kHz +-0.2dB power bandwidth if I am right. A rather significant deviation from spec.

    1. Yup.

      As I noted, if there's one thing I'd take issue with with these amps it's that roll-off. I quickly had a look at the other amp in the pair and I'm seeing a similar frequency response curve so it doesn't look like a "one off" anomaly unless there was a batch of these and I got 2 of 'em.

      Thankfully, the human ear isn't sensitive so I'm not gonna sweat this in practice when listening to actual music with speakers but would have some issue with that published spec.

      Remember guys, we're looking at around -0.6dB @10kHz, -1dB @15kHz, and -2dB @20kHz compared to 1kHz. Never forget the non-linearity of our hearing mechanism and consider the dB variability on something like the Fletcher-Munson curve for context.

    2. yes, conclusion is: datasheets can say anything, better measure.
      And, today its easy to have a bandwidth which is straight.
      I would not tolerate an amp whith such a frequency response. If every part in the chain has two dB loss after several steps its clearly noticeable.
      I will measure my amps. I wonder which amp/company is according specs.

    3. Yeah, that's fair statement depending on one's perspective on tolerances!

      Remember though that I use DSP room correction with a "house curve" that steadily declines by -6dB or so by 20kHz! In that context, the -2dB change would not be a concern for me ;-).

  8. For another example of a well measuring affordable but powerful amplifier, see this French test (using an AP audio analyser) of a 2x350 watt Yamaha P3500s class AB pro audio amplifier: The amplifier is clearly suitable for home audio use. It used to sell for about 350 euro in the Netherlands.
    As a result I bought the 2x250 watt P2500S version for my son, for only 300 euro. It sounds whistle clean, and the fan never comes on in domestic use.
    This series has now been replaced by a new class D series of which I have not yet seen any measurements. I would be very curious indeed.

  9. It's always interesting to see someone not afiliated to a brand or a hifi-magazine make measurements of their products. One might suspect a few things, but not saying anymore ;)

    1. Not sure what you're suspecting Duck, but thanks for the comment about being independent from the Industry! :-)

  10. So, 6 months on, did you stuck with hypex and ditch the emotiva monoblocks or?

    1. Hi Marko,
      6 months on and I am still using the Hypex primarily.

      Still have the Emotiva monoblocks here and might in time give them to friends/family or sell them. Still great amps IMO!

  11. Any thoughts on the newer generation XPA units from Emotiva? In particular, the XPA-DR line? Looking inside they are a significnaly different build from your current monoblocks, and they have migrated to the semi-official "class H" designation. In particular I am looking at the XPA-DR3 line,, which you haven't had the chance to measure yet. Any sense of if these could be contenders?

    Been reading and following along for too many years now (once weighed in on video transcoding, not sure if you went down that path, but there is an updated project that supports glorious Nvidia accelerated encoding now,, and am finally in a position to spend on some speakers. Thinking of pairing the XPA-DR3 with some PSB T3s and a C3 center, any uninformed thoughts before I pull the trigger?

    Much appreciated, keep up the killer work Arch.

  12. Hi Archimago,
    Amazing blog. I searched it and could find anything on John Linsley Hood 1969 amps? Were there any posts on the topic. If not, will there be anything on that? They seem to be quite popular for their simplicity and sound quality.
    Thank you for sharing your knowledge with the masses! :)