BEHRINGER Reference Amplifier A500

[Soundbroker]

What do you define as 'easy' load?

The A500 has been shown in 3rd party testing to perform outstandingly into 4 ohms, with +/- 60 degrees phase lead/lag difference between voltage and current. This is NOT an easy load by any means. This amplifier is specifically suited to very difficult loads.

-Chris

It works well as a stereo amp with 4 ohm loads. But if you monoblock it, which is how a lot of guys are buying them, then you want a load that is higher (both power supply and cooling capacity limit it). As for it being specifically suited to low impedence loads, I guess it depends on what you consider a difficult load. It works well in stereo for a 4 ohm load (which I don't consider particularly difficult). Below that, the A-500 loses it (hey, we are talking about a sub $200 amp here so I cut it a HELL of a lot of slack!). If you have speakers that are inefficient or have impedence dips below 4 ohms (in my experience selling both lines in the past, the Thiels and Dynaudios are both inefficient and have low impedence dips), the bigger fancooled EP-1500 and EP-2500 are actually better suited and rated for those types of loads. They are both 2 ohm rated in stereo and 4 ohm rated in mono. I have all three in the shop...put all three on a set of Klipsch RF-7's which are efficient, but notorious for a 2.7 ohm dip in the bottom end and thus actually hard to drive. Between the A-500 and EP-1500, the 1500 was clearly better on the more difficult speaker. I love the A-500 for what it is and sell it because it is such a great deal (it surely ain't for the profit margin!).

 

[SHomrighausen]

I LIKE 'em...

Yeah, it's possible.
But just run them bridged, turn the gain control all the way up and enjoy the power.

You don't have to tell me twice... I have eight of these gems Building a line array now to use three total (two bridged for midbasses and one stereo for tweeters). One bridged for center channel, two stereo for the surrounds and backs in my 7.1 setup. My IB sub uses an EP2500 bridged... Gotta love CHEAP, CLEAN power! That leaves me two for my 2.0 setup.

I got them with a few coupons from Musicians Friend for $149.49ea delivered! My UPS man hated me that day!

 

[majorloser]

At $150 each you can afford to buy spares

 

[WmAx]

As for it being specifically suited to low impedence loads, I guess it depends on what you consider a difficult load. It works well in stereo for a 4 ohm load (which I don't consider particularly difficult).

Ohms is only one factor the difficulty of a load. The other is the electrical phase angle into which the amplifier must deliver the signal[since speakers are not simple resistors]. The A500 excels in the circumstance of retaining good performance into extreme reactive loads.

If you have speakers that are inefficient or have impedance dips below 4 ohms (in my experience selling both lines in the past, the Thiels and Dynaudios are both inefficient and have low impedance dips), the bigger fancooled EP-1500 and EP-2500 are actually better suited and rated for those types of loads.

The 'Ohm' rating given on an amplifier is for average nominal impedance. Almost any speaker is going to have narrow/localized bands where the impedance is lower than the nominal rating. An amplifier is designed with this in mind.

They are both 2 ohm rated in stereo and 4 ohm rated in mono. I have all three in the shop...put all three on a set of Klipsch RF-7's which are efficient, but notorious for a 2.7 ohm dip in the bottom end and thus actually hard to drive. Between the A-500 and EP-1500, the 1500 was clearly better on the more difficult speaker. I love the A-500 for what it is and sell it because it is such a great deal (it surely ain't for the profit margin!).

How did you remove external factors(level matching, psychological bias, etc.) in your comparison?

-Chris

 

[swest]

Greetings,

I have a couple of questions about the A500 for those in the Know.

I decided to acquire 3 of these amps, to run in bridge-mono mode and drive my fronts (B&W 803 Series II, B&W FCM8 as center). The 803s are nominally rated at 8 ohms, while the FCM8 is rated as 6 ohms. Reading the B&W documentation, I find that the low impedance point for both these speakers is 4 ohms. Unfortunately, I can't find a graph of Impedance vs Frequency for either of these models.

I'm hoping that the 803s do not present any kind of problem, but I'm a little worried about the FCM8.

However, should I expect the negative impact of these numbers to be mitigated by the fact that I crossover these speakers at 80hz to my subwoofer array? Or do you think I'm asking from trouble?

I just ran a test with WotW (the first BLAAAT scene) and the center didn't seem to break a sweat, and never approached clipping (and I was running it at a fairly substantial level... I don't have my SPL meter handy, so I don't know the actual SPL.) If I am heading for problems, will the clip light even provide an indication of it?

Thanks, in advance.

- s.west

 

[WmAx]

Greetings,

I have a couple of questions about the A500 for those in the Know.

I decided to acquire 3 of these amps, to run in bridge-mono mode and drive my fronts (B&W 803 Series II, B&W FCM8 as center). The 803s are nominally rated at 8 ohms, while the FCM8 is rated as 6 ohms. Reading the B&W documentation, I find that the low impedance point for both these speakers is 4 ohms. Unfortunately, I can't find a graph of Impedance vs Frequency for either of these models.

I'm hoping that the 803s do not present any kind of problem, but I'm a little worried about the FCM8.

However, should I expect the negative impact of these numbers to be mitigated by the fact that I crossover these speakers at 80hz to my subwoofer array? Or do you think I'm asking from trouble?

I just ran a test with WotW (the first BLAAAT scene) and the center didn't seem to break a sweat, and never approached clipping (and I was running it at a fairly substantial level... I don't have my SPL meter handy, so I don't know the actual SPL.) If I am heading for problems, will the clip light even provide an indication of it?

Thanks, in advance.

- s.west

The unit should have no problems into a 6 ohm load bridged, assuming that is an accurate nominal impedance rating, and assuming you are not using the amplifier at or near it's power output limits for extended duration(s). The amplifier in question has output stages designed to deal with rather high current requirements(as evidenced by it's excellent results on highly reactive test loads by 3rd party testing). I doubt it would fail during normal use of a nominal load 25% lower than the rated interface nominal load. From personal observations: I have used loads up to 1/2 what is recommended by the manufacturer on many much lesser engineered amplifiers, with years of problem-free operation. The only time problems were encountered is when I tried to use the devices at high power levels into the below-rated loads, at which point over-heating will usually occur. But be warned that it is also possible to burn out the internals of the output transistors, especially on lesser engineered equipment, by way of excessive current flow, or excessive heat due to insufficient heat dissipation. But again, on the A500, this seems highly unlikely considering the specific conditions relevant to your circumstances as presented above.

-Chris

 

[swest]

The unit should have no problems into a 6 ohm load bridged, assuming that is an accurate nominal impedance rating, and assuming you are not using the amplifier at or near it's power output limits for extended duration(s). The amplifier in question has output stages designed to deal with rather high current requirements(as evidenced by it's excellent results on highly reactive test loads by 3rd party testing). I doubt it would fail during normal use of a nominal load 25% lower than the rated interface nominal load. From personal observations: I have used loads up to 1/2 what is recommended by the manufacturer on many much lesser engineered amplifiers, with years of problem-free operation. The only time problems were encountered is when I tried to use the devices at high power levels into the below-rated loads, at which point over-heating will usually occur. But be warned that it is also possible to burn out the internals of the output transistors, especially on lesser engineered equipment, by way of excessive current flow, or excessive heat due to insufficient heat dissipation. But again, on the A500, this seems highly unlikely considering the specific conditions relevant to your circumstances as presented above.

-Chris

Thanks for that response. It sounds like I'm going to be ok, then.

To put some numbers to this, I played some music (rather bass-heavy Sarah McLachlan) in mono mode w/bass-management which runs all program material through the center channel and subwoofers. I left on the bass-management, but turned off the subs (so I could get an accurate SPL measurement from the FCM8. I played it at a loud 107dB @ 1m (peak, as measured by my RS SPL meter, C-weighting) - much louder than I would ever listen - for 1/2 hour, or so. The output was clean with no audible distortion or sense of stress. The peaks occurred on Sarah's vocal material (probably within the octave or 440hz - 880hz.)

The B&W FCM8 is rated at 90dB with 1 watt @ 1m. So I figure we were running 50+ watts. The meters on the amp (bridged-mono) both showed peaks of -6 dB.

After the test period, I felt the heat-sinks and top of the amp. They were warm. However, at the interface between the output stages and the heat sinks, it was nearly too hot to touch.

I also set up a 300hz test tone, and calibrated it to 107dB. Now the amp measured -9dB on its meters. This suggests a little better headroom, no?

Comments?

 

[WmAx]

Thanks for that response. It sounds like I'm going to be ok, then.

To put some numbers to this, I played some music (rather bass-heavy Sarah McLachlan) in mono mode w/bass-management which runs all program material through the center channel and subwoofers. I left on the bass-management, but turned off the subs (so I could get an accurate SPL measurement from the FCM8. I played it at a loud 107dB @ 1m (peak, as measured by my RS SPL meter, C-weighting) - much louder than I would ever listen - for 1/2 hour, or so. The output was clean with no audible distortion or sense of stress. The peaks occurred on Sarah's vocal material (probably within the octave or 440hz - 880hz.)

The B&W FCM8 is rated at 90dB with 1 watt @ 1m. So I figure we were running 50+ watts. The meters on the amp (bridged-mono) both showed peaks of -6 dB.

After the test period, I felt the heat-sinks and top of the amp. They were warm. However, at the interface between the output stages and the heat sinks, it was nearly too hot to touch.

I also set up a 300hz test tone, and calibrated it to 107dB. Now the amp measured -9dB on its meters. This suggests a little better headroom, no?

Comments?

You certainly have a more than adequate level of headroom.

What you did for that test placed more stress on the unit than it will ever experience in real application. Based on your report, a failure would never be due to thermal breakdown in your application during normal use. I would not, however, use it at the extreme test levels mentioned, for long duration(s), as this may potentially have some consequences if repeated on a regular basis.

-Chris

 

[swest]

You certainly have a more than adequate level of headroom.

What you did for that test placed more stress on the unit than it will ever experience in real application. Based on your report, a failure would never be due to thermal breakdown in your application during normal use. I would not, however, use it at the extreme test levels mentioned, for long duration(s), as this may potentially have some consequences if repeated on a regular basis.

-Chris

Roger that.

Two final questions, and then I'll give you a break :

1) When running in bridge-mono, the meters (L + R) match. How do I use these numbers? i.e. if the meters show that peak levels are reaching -6dB (both sides) does that mean that I have 6dB to go before clipping, or 2x6dB (9? dB)... (I'm not sure I understand my own question.)

and:

2) Will the clip indicators (when operated in bridge-mono mode) be meaningful?

Thanks for your insights.

- s.west

 

[nhpm510]

B&K 125.7 vs A500

I have found a used B&K AV125.7 (125 wps) for a resonable price, much less than 7 A-500s. To all the audio scientists and audio gurus, what would be a better choice for my HT? (I already have one A-500 in a bedroom set up, and I think it sounds okay)

My speakers are 8 ohm KEFs. Fairly easy to drive.

I am not all that familiar with B&K, is it more of a custom installer brand?

I do like listening to music as well in the HT. Probably 50/50 mix.
What would you pick, the B&K or the stack of power?

Happy listening..

 

[mantol]

Roger that.

Two final questions, and then I'll give you a break :

1) When running in bridge-mono, the meters (L + R) match. How do I use these numbers? i.e. if the meters show that peak levels are reaching -6dB (both sides) does that mean outhat I have 6dB to go before clipping, or 2x6dB (9? dB)... (I'm not sure I understand my own question.)

and:

2) Will the clip indicators (when operated in bridge-mono mode) be meaningful?

Thanks for your insights.

- s.west

Since you have a negative number on your meter, doubling the power will result an increase of 3 db so your total power would become -3db. 9 db is correct if your reading is +6db. Well, I've not tried this before but if you are interested to determine at what SPL level your clip indicator will trigger you can increase the volume until the clip indicators come on while taking note of the SPL reading. That is if the clipping sensor is connected after the volume control. If it is prior to the volume control of the PA, then this can be done by raising the volume of the source connected at the input of the PA. Please take care not to damage your hearing permanently by putting on your headphone.

The bridge-mono mode is actually connecting your output stages in series that's why the load impedance requirement should be twice the rating per channel. I suppose the clip indicator will still respond as designed by the manufacturer in whatever configuration you may desire i.e, bridge-mono or stereo.

 

[jcrobso]

I have used Behringer amps. They make very good budget pro sound gear. John

 

[majorloser]

I have found a used B&K AV125.7 (125 wps) for a resonable price, much less than 7 A-500s. To all the audio scientists and audio gurus, what would be a better choice for my HT? (I already have one A-500 in a bedroom set up, and I think it sounds okay)

My speakers are 8 ohm KEFs. Fairly easy to drive.

I am not all that familiar with B&K, is it more of a custom installer brand?

I do like listening to music as well in the HT. Probably 50/50 mix.
What would you pick, the B&K or the stack of power?

Happy listening..

If it means anything, I replaced a B&K Ref. 7270 Ser. 2 amp (7x200wpc) for seven Behringer A500's. No regrets at all.

B&K Components is more of a "middle of the line" manufacturer. They are sold through some of the larger audio chain stores, like Tweeters and Sound Advice. B&K gets very good ratings and is good quality equipment.

You have to remember that the 7 Behringer amps wil give you almost 500wpc into 8 ohms vs. the 125wpc with the B&K AV125.7 amp. If you have room for the big stack of amps and enough AC outlets to feed them it can be a definite gain. It might be better to compare the A500's in their stereo amp mode rather than mono bridged if you are comparing vs. the B&K amp. In stereo they are rated at 2x160wpc. It would only take 4 A500's to equal the 7 channels of the B&K. At that point you could run one channel bridged or have one channel as a spare (even two center channels?).

 

[nhpm510]

Despite ur name..ML

I do value you your opinion. You steered me right with the monoprice HDMI switcher already. I even have one A500 already due to your tower of madness! I am using the A500 in the masterbed room. Really brought those speakers alive.

Space and outlets are considerations, so I was thinking of a possible one amp solution. Who knows, maybe the Emotiva UL amp if B&K didn't do it?

Quick question, where do you keep the volume knobs on the A-500s? 50% power, or all the way?

Cheeers

 

[majorloser]

I'm running my amps bridged. I have the gain knobs turned up half way. Yes, I could turn them up all the way but I haven't needed it.

 

[Soundbroker]

Ohms is only one factor the difficulty of a load. The other is the electrical phase angle into which the amplifier must deliver the signal[since speakers are not simple resistors]. The A500 excels in the circumstance of retaining good performance into extreme reactive loads.

The 'Ohm' rating given on an amplifier is for average nominal impedance. Almost any speaker is going to have narrow/localized bands where the impedance is lower than the nominal rating. An amplifier is designed with this in mind.


How did you remove external factors(level matching, psychological bias, etc.) in your comparison?

-Chris

Agreed on the reactive loads...but the RF-7's we had them are are known to be not only very reactive but also have one hell of a dip in the low impedence range near the resonance frequency of the woofer. This speaker has given quite a few amps fits and fooled a lot of people who only look at the very high efficiency rating. Bridged the A-500 flat out lost control of the woofers and got pretty damned toasty (we have a fan system that keeps our rack of A-500's cool...without that, chances are the amp would have thermaled out). Swapping to the EP-1500 was better...2500 was even better in regards to controlling the low frequencies at high levels. This was in a properly acoustically treated 8500 ft3 space which does suck up a lot of power due both to room size and a lot of acoustic treatments. On the far easier to run Klipsch KL-650 THX Ultra 2 mains which are crossed over at 65 hz...there was no real difference between the three amps.

Levels were matched on a calibrated setup to within 1 db. Psychologically, all I can say is that I was expecting the A-500 to take the win since it had the most horsepower...but it was pretty clear that on those particular speakers, the EP series amps were a better choice.

 

[mtrycrafts]

Agreed on the reactive loads...but the RF-7's we had them are are known to be not only very reactive but also have one hell of a dip in the low impedence range near the resonance frequency of the woofer. This speaker has given quite a few amps fits and fooled a lot of people who only look at the very high efficiency rating. Bridged the A-500 flat out lost control of the woofers and got pretty damned toasty (we have a fan system that keeps our rack of A-500's cool...without that, chances are the amp would have thermaled out). Swapping to the EP-1500 was better...2500 was even better in regards to controlling the low frequencies at high levels. This was in a properly acoustically treated 8500 ft3 space which does suck up a lot of power due both to room size and a lot of acoustic treatments. On the far easier to run Klipsch KL-650 THX Ultra 2 mains which are crossed over at 65 hz...there was no real difference between the three amps.

Levels were matched on a calibrated setup to within 1 db. Psychologically, all I can say is that I was expecting the A-500 to take the win since it had the most horsepower...but it was pretty clear that on those particular speakers, the EP series amps were a better choice.

You were trying to fill an 8500 cu ft room with the low frequency? I think you are over driving even that amp. And, in bridged mode, it is not rated into 4 ohms.

By the way, 1 dB level matching is way out of accepted practice. You need a voltmeter and measured at the speaker terminal to 1% of voltage. That should give a .1dB spl level matching, the standard.

 

[wire]

And, in bridged mode, it is not rated into 4 ohms.

I agree , most amps bridged dont like anything under 8 ohms . Your gonna fry it .

 

[mike c]

I'm assuming the clip meters up front are for the left and right channels ... do the lights still move about in bridged mode? (both left and right?)

 

[majorloser]

What would you pick, the B&K or the stack of power?

I replace a B&K Ref 7270 amp with seven A500's and haven't looked back. It was a huge difference. I still have the B&K and don't know what I'll do with it now.

Mike: the meters still operate when the amps are bridged. LED on both side go up together. Can get quite hipnotic with a stack of seven amps.