Review and Measurements of Behringer A500 Amplifier

[A800]

If it's the DCX2496 and not the DCX2496LE it should have 3 inputs one of which you can configure as a AES/EBU digital input.

 

[sergeauckland]

How do you feed digital stream to the DCX 2496 ? It has not got optical or coax inputs.

If it's the DCX2496 and not the DCX2496LE it should have 3 inputs one of which you can configure as a AES/EBU digital input.

That's right. The DCX2496 has both analogue and digital inputs. I feed mine from the digital output of the DEQ2496 which is used as my ADC for all my source, as well as it's main function of equalising my 'speakers.

S

 

[A800]

The DEQ is also a great device.
I love mine.

 

[Pulkass]

No, you should not use the RCA inputs. There's too much voltage gain (39db) associated with those which then causes you to turn the controls down to compensate....which incurs the extra distortion.
It's preferable to use the XLR inputs with an RCA/XLR adaptor. The voltage gain of the amplifier is 27db in that case, and the controls can stay at maximum.

You could use the RCA inputs if your upstream components (source, preamp, etc) were low/marginal in voltage gain. Or, maybe use an (approximate 12db) attenuator.

FYI, the two o'clock position of the controls reduces gain by 12db.

Dave.

Thanks I ve set the pot at e l e v e n eheheheh so to say maximun ---I regulate volume on my elec x over, my DBX 234--but I d like to ask :-can I change the op amps inside the dbx ?? for and updated sound??? it s 20 years old, great server has been, excellent.

 

[Deleted member 2944]

Thanks I ve set the pot at e l e v e n eheheheh so to say maximun ---I regulate volume on my elec x over, my DBX 234--but I d like to ask :-can I change the op amps inside the dbx ?? for and updated sound??? it s 20 years old, great server has been, excellent.

I don't know what sort of "updated sound" you're looking for, (or how changing op-amps would give it to you) but, if your dbx is still working good I suggest to just leave it alone.
If you want to get some "updated sound" I think better to change power amplifiers.

Dave.

 

[Pulkass]

I don't know what sort of "updated sound" you're looking for, (or how changing op-amps would give it to you) but, if your dbx is still working good I suggest to just leave it alone.
If you want to get some "updated sound" I think better to change power amplifiers.

Dave.

Thanks. I use 4 amps. In a 3 way config. The sound is of my utter satisfaction. 2 mono for bass and 2 stereo mid and highs. I ve just rejuvenated it, substitung the excellent Half dome tweeters by Morel with new Celestion compression drivers and horns. Very big treated room. Very loud music. Almost studio setting. Almost like the good expensive JBL s . Attack is spine chillin. Fast. Violin is done correct . Piano is done correct...... Lots in exchange for little money.

 

[gene_stl]

Don't bother changing the op amps. Very inadvisable and not audible.

 

[Pulkass]

Don't bother changing the op amps. Very inadvisable and not audible.

Thanks. I won't be spending a dime.

 

[wje]

Gee, thanks for rejuvenating this thread. I'm going to put my A500 back into service tonight and see what my latest impressions of it are. Also, I nabbed a Crown XLS 1502 for $325, shipped that will arrive this week. I got distracted on my way home tonight and picked up mint pair of B&W D602 S3 speakers. From what I've read, lots of improvements can be made to the crossovers by going to Poly caps from the old electrolyte caps that were used during manufacturing. However, as is, the sound is pretty good for a 15 year old speaker. Mint condition for $100. :O

 

[wje]

I brought the A500 back out and put it in place of the NX6000D amplifier. Some initial sound observations. The A500, seemed a bit more neutral to ever so slightly warmer sounding than the NX6000D. Though, the difference is slight, I could note it after listening to several of my typical jazz tracks in my rotation. Granted, this wasn't a scientific test, or a double blind test for that matter, but just my observations based on listening. Using the B&W DM602 speakers, many in the past would call these quite a detailed speaker. But, even when compared to newer speakers, I don't find the DM602 S3 fatiguing in any way. In my swap, I did have to use different speaker cables though because the NX6000D required the use of Speakon connectors instead of banana plugs like the D500 is capable of utilizing. For both amps, I was utilizing the balanced inputs. The great thing is that because of the reasonable cost of many of these components, one doesn't have to anguish too much because they're not multiple-thousand dollar amps and swapping, buying and selling them can be relatively easy on our wallets.

 

[Specialcause]

It's worth a try. Those pots are very cheap, and are not likely to last long if they are used as volume controls. They're really intended as 'set and forget' controls. Mine are fine, but they have hardly ever been turned in the past 5 years or so. If contact cleaner doesn't work, they're easy enough to replace, preferably with something of better quality.

S

Since getting A500 (new) about 3 years ago I haven't used pots as volume control but I have followed the advice in the manual: Both volume controls should be turned all the way to the left whenever you power the unit up or down. So they've been twiddled a fair bit. The last time I turned on the A500 there was a short, loudish thud on the right speaker and when I started to turn up the right channel knob there was a slightly louder noise. Is this the same problem Pulkas had – heavy noises? If so I’d be inclined to replace the pots, ‘preferably with something of better quality’ as you suggested. Are there any you would recommend and could you give me an idea of what the job entails. I suspect it requires soldering iron skills so I'd be looking for assistance from somebody near me who has them.

Phil

 

[sergeauckland]

Since getting A500 (new) about 3 years ago I haven't used pots as volume control but I have followed the advice in the manual: Both volume controls should be turned all the way to the left whenever you power the unit up or down. So they've been twiddled a fair bit. The last time I turned on the A500 there was a short, loudish thud on the right speaker and when I started to turn up the right channel knob there was a slightly louder noise. Is this the same problem Pulkas had – heavy noises? If so I’d be inclined to replace the pots, ‘preferably with something of better quality’ as you suggested. Are there any you would recommend and could you give me an idea of what the job entails. I suspect it requires soldering iron skills so I'd be looking for assistance from somebody near me who has them.

Phil

Yes, the pots need to be soldered to a small PCB. If I were replacing the pots, I'd get some conductive plastic pots, ALPS perhaps, as these are as good as need to be. By the way, I've never turned the pots off when switching the amp on and off, all I get with the pots at full is a small click at switch-on, nothing at switch-off.

S.

 

[Deleted member 2944]

The reason they suggest turning the pots down on power up is because of (possibly) unknown input signal. (This is a not uncommon practice in pro-sound usage.)

In a domestic environment, most all of us are perfectly aware what signal and signal levels will be present when turning an amplifier on, so it's completely unnecessary to ever adjust the pots.

Dave.

 

[Specialcause]

Yes, the pots need to be soldered to a small PCB. If I were replacing the pots, I'd get some conductive plastic pots, ALPS perhaps, as these are as good as need to be. By the way, I've never turned the pots off when switching the amp on and off, all I get with the pots at full is a small click at switch-on, nothing at switch-off.

S.

Thanks Serge - and for your very helpful responses to my other A500 related posts today. In one of those regarding channel balance you said when the knob is turned all the way up 'the pot wiper is in contact with the end-stop'. In that position does the problem with 'heavy noises' simply not occur because there is good contact? If so I will just leave the pots at full and forego replacing them. Maybe I'd apply some de-oxit spray too if getting at the pots is a case of removing the screws on front panel only.

I was setting the pots at midway but my passive volume controller does have switchable attenuation of 10dB and 20dB so I can reduce the gain to one of those levels - or get attenuators for inputs on A500 if I need something in-between those values.

Phil

 

[Specialcause]

The reason they suggest turning the pots down on power up is because of (possibly) unknown input signal. (This is a not uncommon practice in pro-sound usage.)

In a domestic environment, most all of us are perfectly aware what signal and signal levels will be present when turning an amplifier on, so it's completely unnecessary to ever adjust the pots.

Dave.

Ah yes the A500 is aimed at pro-sound users. It did occur to me that domestic amps I had before never had gain controls and they had to be turned off at full gain. Yet I still slavishly followed the A500 manual despite upstanding members of this forum saying that wasn't necessary or what they did. I've learned my lesson!

Phil

 

[sergeauckland]

Thanks Serge - and for your very helpful responses to my other A500 related posts today. In one of those regarding channel balance you said when the knob is turned all the way up 'the pot wiper is in contact with the end-stop'. In that position does the problem with 'heavy noises' simply not occur because there is good contact? If so I will just leave the pots at full and forego replacing them. Maybe I'd apply some de-oxit spray too if getting at the pots is a case of removing the screws on front panel only.

I was setting the pots at midway but my passive volume controller does have switchable attenuation of 10dB and 20dB so I can reduce the gain to one of those levels - or get attenuators for inputs on A500 if I need something in-between those values.

Phil

With the pots at full, there's shouldn't be any noises from the pots, but if they pots are old or worn, then some contact cleaner should help. If you're using the RCA inputs, those have 14dB more gain than the balanced inputs, so I would always use the balanced inputs and just strap pins 3&1 on the XLR for unbalanced use or use the jacks as they're simply in parallel with the XLRs.

S

 

[Specialcause]

With the pots at full, there's shouldn't be any noises from the pots, but if they pots are old or worn, then some contact cleaner should help. If you're using the RCA inputs, those have 14dB more gain than the balanced inputs, so I would always use the balanced inputs and just strap pins 3&1 on the XLR for unbalanced use or use the jacks as they're simply in parallel with the XLRs.

S

I use the jack/TS inputs – my source output is by RCA only but I have an RCA to jack adapter. Before the pot started making noises I had been thinking that the A500 is too powerful for my needs since I am going through the A500’s unbalanced circuit which is less sensitive and I still have gain controls set at mid-way. I have a lower powered amp (62 watts into 8 ohms) that I could switch to. The last time I used it was with 4 ohm speakers and I put it in storage after getting the A500 to use with them. A couple of years ago I changed these 18 year-old speakers. The new ones are an easier load being 8 ohm nominal and 6 ohm minimum and, though less efficient (84dB), I reckon I’d have more than 20dB headroom with 60 watts as I don’t play very loud and listen about 8ft away. The only unknown is how the damping factor of this amp compares to the A500. A figure isn’t given in the manual and the manufacturer can’t provide it. If my theory proves to be wrong I can always go back to A500 once the pots have been cleaned - or replaced if that doesn't fix it.

 

[sergeauckland]

I use the jack/TS inputs – my source output is by RCA only but I have an RCA to jack adapter. Before the pot started making noises I had been thinking that the A500 is too powerful for my needs since I am going through the A500’s unbalanced circuit which is less sensitive and I still have gain controls set at mid-way. I have a lower powered amp (62 watts into 8 ohms) that I could switch to. The last time I used it was with 4 ohm speakers and I put it in storage after getting the A500 to use with them. A couple of years ago I changed these 18 year-old speakers. The new ones are an easier load being 8 ohm nominal and 6 ohm minimum and, though less efficient (84dB), I reckon I’d have more than 20dB headroom with 60 watts as I don’t play very loud and listen about 8ft away. The only unknown is how the damping factor of this amp compares to the A500. A figure isn’t given in the manual and the manufacturer can’t provide it. If my theory proves to be wrong I can always go back to A500 once the pots have been cleaned - or replaced if that doesn't fix it.

If you're going through the jacks, then you're using the balanced inputs, even if you're unbalancing the jacks with an adapter. Your sensitivity then is still +4dBu (1.44V) with the volume controls at full. The unbalanced RCA inputs are 14dB more sensitive at -10dBu (250mV).

If the 60 watt amp is SS, not tubed, I wouldn't worry about damping factor, it's likely to be quite sufficient unless very odd. The A500 has an output impedance of 0.234 ohms at 20Hz, 0.185 ohms at 1kHz, so a lot higher than the spec of 0.036 ohms (frequency not specified) but that's not surprising for Behringer where their specs are somewhat optimistic (or measured under rather different conditions). As a Behringer fan, I ignore their specs and just accept that whatever they do, it's normally perfectly adequate, just not to spec.

S.

 

[Deleted member 2944]

I suspect he meant to say "balanced" and not "unbalanced."

Regardless, as I've mentioned previously, any operation of the A500 with the controls at less than maximum compromises the measured distortion performance of the amplifier.

Dave.

 

[Specialcause]

If you're going through the jacks, then you're using the balanced inputs, even if you're unbalancing the jacks with an adapter. Your sensitivity then is still +4dBu (1.44V) with the volume controls at full. The unbalanced RCA inputs are 14dB more sensitive at -10dBu (250mV).

If the 60 watt amp is SS, not tubed, I wouldn't worry about damping factor, it's likely to be quite sufficient unless very odd. The A500 has an output impedance of 0.234 ohms at 20Hz, 0.185 ohms at 1kHz, so a lot higher than the spec of 0.036 ohms (frequency not specified) but that's not surprising for Behringer where their specs are somewhat optimistic (or measured under rather different conditions). As a Behringer fan, I ignore their specs and just accept that whatever they do, it's normally perfectly adequate, just not to spec.

S.

My amp is SS. So the A500 has a much lower output impedance than the manual claims...

One thing that has confused me is the input sensitivity of the A500. The manual claims it is 1.64V which fits with what Peter Aczel measured back in 2005: ‘the maximum output is a little over 33 volts at the test limit of 1% distortion’ (1.64 x gain of 20). That would make the sensitivity +6.5dBu, according to the online sengepielaudio calculator, but the balanced inputs are labelled as +4dBu. So my confusion is which figure to use (+4dBu or +6.5dBu) when working out how much attenuation to use given max output of the source – in your case +22dBu (9.75V), I believe, and in mine +8.7dBu (CD- level of 2.1 V)? I realise that some A500 users would not bother with attenuation for CD-level max voltage.