Review and Measurements of Behringer A500 Amplifier

[amirm]

This is a review and detailed measurements of the Behringer A500 "Reference" Power amplifier. I purchased this unit on suggestions from members from Amazon for just $199 including Prime shipping.

Being targeted at the pro market, this is rack-mount unit with heft heatsinks on each side:

Full compliment of inputs are provided from RCA to balanced XLR and TRS. No input selector is provided though and the manual warns against simultaneous connection to more than one input.

The plastic volume knobs feel cheap but otherwise, it seems to be a sturdy build.

The manual says it has a class AB output stage. I am assuming some kind of power rail voltage switching is used to keep power consumption generally low but I have not confirmed this.

For my testing, I used a 4 ohm dummy load and balanced XLR inputs. Let's get into measurements and see how she did.

EDIT: the first revision of this review had tested the A500 with the input switch set to bridged. It has now been updated in proper stereo mode.

Measurements
Let's start with our dashboard:

Even though I was using balanced input and outputs from the amplifier, we see large contributions from noise from the power supply in the form of 120 Hz and multiple harmonics.

The harmonic distortion is quite high too with distortion spikes seemingly going on forever. So even if the power supply was 100% quiet, it would likely still not get better distortion/sinad rating. A dismal showing regardless, underperforming good DACs by whopping 40 db!

Signal to noise ratio is rated at 100 and I get numbers reasonably close to it:

Here is distortion versus power:

Sad to see a class AB amp not be able to outdo the switching amp in the Topping TP60 with respect to distortion and noise where the two overlap.

Thankfully the Behringer A500 has copious amount of power, producing nearly 170 watts prior to clipping. Behringer's rating is 180 watts at 1% distortion which seems like an honest rating.

Frequency response is OK but not as flat as it should be for a power amp in the audible range:

If there is rail supply switching, then it likely has an output filter to get rid of switching noise from that and as a result, start to roll off the response as we see above.

I think we have a good picture of A500 performance so let's not torture ourselves anymore.

Conclusions
We seem to have a stream of bad luck with bargain amplifiers. Sure, they provide exceptional value in how little they charge per watt. I know I can't make and ship the empty case of this amplifier for $199. But still, we want good distortion specs that rise up at least to some of the worst DACs we have ever tested. Heck, these numbers are no better than some analog formats!

Given the high distortion levels and somewhat uneven frequency response, I can't recommend the Behringer 500. If you just want loud amplification, then you do have a bargain here.

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As always, any questions, concerns, comments, corrections, etc. are welcome.

If you like this review, please consider donating using Patreon (https://www.patreon.com/audiosciencereview), or upgrading your membership here though Paypal (https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054). It will enable me to pay for gear that is not offered for loan.

 

[sergeauckland]

The A500 provides for bridged connection which causes the volume controls to work exactly as you described. Are you sure the 'bridged' switch was in the stereo position?

I have the circuit diagram, and there is no power rail switching, just pretty standard Class AB circuit. Where it is slightly unusual is that it only has a single floating rail with an artificial 'centre' which in effects AC couples the load to the amp.

I can post the circuit if anyone's interested.
S

 

[JJB70]

Just one slight correction, Behringer are German, not American. Great review though. I am familiar with a lot of their pro gear as I use it on a sound desk and it is a bit jeckyl and hyde. Some of genuinely very good and an absolute bargain, other stuff they make is junk. But I suppose at least it is low(-ish) cost as opposed to a lot of much more expensive junk that doesn't even have the saving grace of low cost.

 

[RayDunzl]

Here though, we have a reversal with the American branded product clearly not being tested to catch assembly problems.

Just one slight correction, Behringer are German, not American.

Well, at least it's made in China...

 

[JJB70]

Well, at least it's made in China...

View attachment 17174

True, but then again most ostensibly European, US and Japan audio gear is manufactured there these days (and quite a few of those brands nowadays are actually Chinese through ownership too). I may be wrong but AFAIK Behringer are still a German company with production in China. Even Sennheiser had a lot of their production in China.

 

[amirm]

The A500 provides for bridged connection which causes the volume controls to work exactly as you described. Are you sure the 'bridged' switch was in the stereo position?

Ah, the switch was hidden under my cable. And yes, it was in mono bridged mode.

 

[Ron Texas]

There have been numerous reports of serious defects in new A500 amps. Someone did a test and found lowering the volume controls on the front of the amp cause distortion to rise to .4% from under .1%. My understanding is there is no speaker protection. Thank you Amir.

 

[Ron Texas]

Ah, the switch was hidden under my cable. And yes, it was in mono bridged mode.

Time for a new set of measurements...

 

[andreasmaaan]

It seems that various cheap class D amps are letting us down terribly here

I'm very disappointed TBH. I've used a number of slightly more expensive class D amps over the years and all of them have measured far better than those you've been unfortunate enough to get your hands on @amirm.

Was hoping for better from Behringer in particular...

EDIT: I just saw the price tag. For some reason I thought this amp cost more like $350. I don't think the performance is bad given the price/power ratio, to be fair.

 

[JJB70]

I have an A800 for the sound desk, one thing I'll say for it is that it is ****** powerful. And it was cheap.

 

[sergeauckland]

I'm also surprised at trying to judge a power amplifier by DAC criteria. A power amplifier with a SINAD of -60dB at any frequency and any permitted load is transparent, and that's all that's required for fidelity. There's no benefit except specmanship to do more. In those terms, the A500 is adequate for the task. That other amplifiers can do better at higher cost is besides the point.

S

 

[FrantzM]

I have a Behringer all waiting to be opened up for Sub duties.. I'll save myself the bother, seel it at cost and buy a Crown amp for much more ...

 

[sergeauckland]

There have been numerous reports of serious defects in new A500 amps. Someone did a test and found lowering the volume controls on the front of the amp cause distortion to rise to .4% from under .1%. My understanding is there is no speaker protection. Thank you Amir.

Moving the volume control can change the DC conditions slightly, and therefore it's possible the amp may have higher distortion whilst the DC servo rebalances, which takes a while as it has a long time constant. The volume pots are not intended as an operational control like a fader, so I suppose it's acceptable for the amp to do that, even if it were better if it didn't. I use mine with the volume controls at maximum, so the problem doesn't arise, and never bothered to measure distortion at part setting. If redoing the measurements now kn stereo mode, it might be an idea to take another set with the volume control reduced, giving a few seconds for the servo to rebalance.

S

 

[vert]

It seems that various cheap class D amps are letting us down terribly here

I'm very disappointed TBH. I've used a number of slightly more expensive class D amps over the years and all of them have measured far better than those you've been unfortunate enough to get your hands on @amirm.

Was hoping for better from Behringer in particular...

Could you give some examples of such amps

 

[andreasmaaan]

Could you give some examples of such amps

Yeh sure

I used to have one of these in my home setup which measured slightly better than the ones Amir's tested. It's way out of date now ofc, and was a lot more expensive at the time.

I use these in PA speakers, all of which measure a lot better than the ones tested here (at least according to the manufacturer - I don't have the means to test them myself). These boards cost between about 200 and 500 Euro depending on the power output and number of channels etc, but are OEM only.

And then there are the various Hypex- and ICE-based units that measure better again. This one for example, which costs 370€ including case, PS and connectors.

 

[andreasmaaan]

@amirm I think it's very important when measuring these amps to take a THD vs frequency sweep if possible?

A lot of class D amps, especially cheaper ones, exhibit rising distortion with frequency. Taking THD measurements at only 1KHz could hide some audible issues.

 

[anmpr1]

http://www.biline.ca/audio_critic/audio_critic_web2.htm#ba

FYI. Above is a link to another review with some measurements.

 

[stunta]

@amirm I think it's very important when measuring these amps to take a THD vs frequency sweep if possible?

A lot of class D amps, especially cheaper ones, exhibit rising distortion with frequency. Taking THD measurements at only 1KHz could hide some audible issues.

Is it also not important to measure the distortion with varying impedance? From my very limited (and quite possibly misplaced) knowledge, not all amps are good at handling speakers that have a wild impedance curve.

 

[amirm]

I set the switch and remeasured. Not much changed since I was testing the outputs as stereo as opposed to bridged. I updated the dashboard, power and text to reflect the new findings ion the review.

 

[Grave]

How hard can it be to make a power amplifier with a SINAD of > 80 dB?