I have a few Behringer A500 power amps. Channel 1 in one of them roars for several seconds when it's switched on before settling down. I think I've also heard intermittent clicks/pops.
I'm nervous of driving my active speakers with this as something is clearly wrong. I have a little experience with a soldering iron and physics, but I'm pretty ignorant about the details of amplifier electronics.
What is likely to have gone wrong, and how can I find it with my 'SMART^2' multimeter? I've had the amp open but couldn't see anything obviously burnt. Any chance of a little kindly guidance? Thanks in advance...
I'm nervous of driving my active speakers with this as something is clearly wrong. I have a little experience with a soldering iron and physics, but I'm pretty ignorant about the details of amplifier electronics.
What is likely to have gone wrong, and how can I find it with my 'SMART^2' multimeter? I've had the amp open but couldn't see anything obviously burnt. Any chance of a little kindly guidance? Thanks in advance...
Wait a minute you are going to use a POWER amplifier to drive ACTIVE loudspeakers -- words fail me - oh I see you are not well up on amplifier electronics .
The inputs to active loudspeakers have RCA / phono & XLR inputs as "active " usually means a big amplifier inside the loudspeaker enclosure driving the woofer & tweeter---DON'T try that !
As regards your fault it could be a dirty switch or a high resistance soldered joint .
Your amps have a bridging switch =S1A and S1B check the contacts .
The inputs to active loudspeakers have RCA / phono & XLR inputs as "active " usually means a big amplifier inside the loudspeaker enclosure driving the woofer & tweeter---DON'T try that !
As regards your fault it could be a dirty switch or a high resistance soldered joint .
Your amps have a bridging switch =S1A and S1B check the contacts .
Thank you! These are active speakers with external crossover boxes and no internal amps. Although I'm relatively ignorant, I know enough to put the crossover upstream of one set of power amps!
I've gradually been adding amps with the goal of running ten in bridged mode with my 5-way speakers. The last pair I bought cost me £16 each. One more pair and I can run all ten amps bridged which will make setting gain simpler.
How would I go about detecting a dirty switch? Should I just test for resistance across points which should be shorted by the switch?
Thanks a lot for your suggestions.
I've gradually been adding amps with the goal of running ten in bridged mode with my 5-way speakers. The last pair I bought cost me £16 each. One more pair and I can run all ten amps bridged which will make setting gain simpler.
How would I go about detecting a dirty switch? Should I just test for resistance across points which should be shorted by the switch?
Thanks a lot for your suggestions.
Just go ahead and clean all the switches and contacts. This is standard practice when
putting used equipment into operation. No substitutes on the cleaner.
https://www.amazon.com/Hosa-D5S-6-DeoxIT-Contact-Cleaner/dp/B00006LVEU
putting used equipment into operation. No substitutes on the cleaner.
https://www.amazon.com/Hosa-D5S-6-DeoxIT-Contact-Cleaner/dp/B00006LVEU
Thanks for the clarification. My speakers have a disconnectable crossover so they can be driven passively or non-passively. To drive them non-passively you disconnect the passive crossover, so that they are in non-passive configuration and connect amps which you feed from a powered non-passive crossover upstream of the power amps. I wasn't sure what to call that so I called it active. Sorry for the confusion!
This page suggests that my previous understanding of passive is also understood. It says an active system has a powered crossover at line level whereas a passive system contains a crossover which does band filtering at amp output levels. That's what I always understood the difference to be in the old days:
Active vs passive speakers: what's the difference? Which is better? | What Hi-Fi?
Perhaps usage has changed in hifi now that internal amped speakers are more common these days.
Active vs passive speakers: what's the difference? Which is better? | What Hi-Fi?
Perhaps usage has changed in hifi now that internal amped speakers are more common these days.
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Nobody has yet asked for your speaker details & usage.
10 x 600W into 2 x 5 way speakers sounds a lot to me although I am ignorant of pro-sound systems.
Bass requires more power than treble and in hi-fi it is common to use lower power for tweeters.
Are these truly 5 way speakers or are bass drivers duplicated?
Seems to me it would be more efficiently done with line level crossovers or DSP.
10 x 600W into 2 x 5 way speakers sounds a lot to me although I am ignorant of pro-sound systems.
Bass requires more power than treble and in hi-fi it is common to use lower power for tweeters.
Are these truly 5 way speakers or are bass drivers duplicated?
Seems to me it would be more efficiently done with line level crossovers or DSP.
Imagine if you can that some of us haven't jumped out of a plane in flight... !!
Sounds like a leaky/dry electrolytic cap reforming when the supply turns on.
I thought having too much power wasn't a problem. It makes it simpler to have the same amp on each drive unit. They are quite cheap - the last two I picked up were £16 each.
My crossovers are line level.
The bass cones are not big. There are two in each speaker and they are labelled 'upper bass' and 'lower bass'. My understanding is that the upper bass one overlaps range with the lower bass one but cuts off at a higher frequency. There is also a servo sub with a bigger cone which is set to run in mono. The sub's high pass output goes to the crossovers but the high pass is set to 10Hz so is effectively inactive.
I'm sure such a system is not to everyone's taste but I didn't expect this thread to be about that. There are many ways to skin a cat.
Lost the bit about line level active crossovers in your posts.
Not saying too much power is or isn't a problem but it does seem excessive.
It could be a problem if by accident you apply 600W to a tweeter that cannot take it.
Using the bridged amps for bass & as 2 channel amps for treble should give you ample power.
In a conventional speaker level crossover, the tweeters are always padded down with a resistor anyway as they need much less power.
Cheap or not, no point in using more amps than you need, if nothing else, idle power consumption will go up needlessly.
Levels will be set in your crossover however you amp it up.
Not saying too much power is or isn't a problem but it does seem excessive.
It could be a problem if by accident you apply 600W to a tweeter that cannot take it.
Using the bridged amps for bass & as 2 channel amps for treble should give you ample power.
In a conventional speaker level crossover, the tweeters are always padded down with a resistor anyway as they need much less power.
Cheap or not, no point in using more amps than you need, if nothing else, idle power consumption will go up needlessly.
Levels will be set in your crossover however you amp it up.
There is no such thing as too much power ;-)
Sending unfiltered bass through your tweeters is going to break them with any amp that isn't for headphones.
The bridged amps give me more headroom on bass drivers. The argument for using bridged amps on tweeters is (1) the amps are very cheap and (2) it is much easier for me to eq the 5 drive units if amps are all set to same level of gain. The crossovers also have per-channel gain adjusters so the convenience of setting all power amps to the same gain level does not preclude per-driver equalisation.
As regards idle power consumption, the answer is to turn them off when not in use. They are not valve amps and they warm up quickly.
I'm very grateful for all advice.
Sending unfiltered bass through your tweeters is going to break them with any amp that isn't for headphones.
The bridged amps give me more headroom on bass drivers. The argument for using bridged amps on tweeters is (1) the amps are very cheap and (2) it is much easier for me to eq the 5 drive units if amps are all set to same level of gain. The crossovers also have per-channel gain adjusters so the convenience of setting all power amps to the same gain level does not preclude per-driver equalisation.
As regards idle power consumption, the answer is to turn them off when not in use. They are not valve amps and they warm up quickly.
I'm very grateful for all advice.
Idle power, not standby power.
An amp consumes power whatever the signal level. More amps = more power.
We should all be concerned about needless power consumption.
I presume you have a pre amp with master volume control rather than moving 10 volume controls when you wish to adjust volume? Have you implemented an input mute to avoid switch on pops? Do the speakers have tweeter protection capacitors?
An amp consumes power whatever the signal level. More amps = more power.
We should all be concerned about needless power consumption.
I presume you have a pre amp with master volume control rather than moving 10 volume controls when you wish to adjust volume? Have you implemented an input mute to avoid switch on pops? Do the speakers have tweeter protection capacitors?
Yes, this is why I always play my music at a level that is only just loud enough to hear. Any louder and I would be tortured by the thought that I might have reduced the opportunity for a 'developing' nation with an advanced nuclear weapons programme to build another coal-fired power station. Loud music can never be a substitute for publicly-exemplary conscientiousness and a genuine intention to control the output of the sun.
The speakers do not have protection so I should probably introduce a few capacitors. I have used this system for several years without blowing a tweeter by turning gain to zero before powering on/off the amps. Perhaps I've just been lucky. My passive volume control has mute and remote control, but I don't see how that helps since it is upstream of the crossovers.
The analysis of the general inadequacies of my system is a bit off-topic. I'm very grateful for the advice on how to fix what looks like an ailing old budget power amp.
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