Evening all, I mentioned in another thread I loaned a friend a Behringer amp and have now found quite cheaply the 4 channel amp epq304 for him so that I can reclaim my amp for subwoofer duty.
The fans are quite noisy and research on the web has come up with someone completely disconnecting them, someone adding resistors to slow them down and some one replacing with quieter fans.
I have attached a photo from the web but checked that my friends is identical layout.
Why am I posting in the power supply section you ask?
Well I want to fiddle with this amp because I may have other uses for it but don’t want to get killed in the process.
In general domestic use with fans it runs stone cold. Without the top lid it runs stone cold and oddly is not as noisy. I have touched the heat sink on the amp section and survived so it is not live but am far more wary of the power supply.
My primitive way of experimenting in this instance would be to run the amp reasonably hard and touch the heat sinks to check temperature. Obviously safer would be to first unplug the power cord but for this type of power supply would, in general of course, the heat sinks be live and even if the power cord is removed would there be enough energy stored to shock?
I could measure with a multimeter but are these ac or dc and is the reference chassis ground or does the power supply float.
Any comments appreciated and please understand that I am at least smart enough not to kill myself.
Thanks, sp
The fans are quite noisy and research on the web has come up with someone completely disconnecting them, someone adding resistors to slow them down and some one replacing with quieter fans.
I have attached a photo from the web but checked that my friends is identical layout.
Why am I posting in the power supply section you ask?
Well I want to fiddle with this amp because I may have other uses for it but don’t want to get killed in the process.
In general domestic use with fans it runs stone cold. Without the top lid it runs stone cold and oddly is not as noisy. I have touched the heat sink on the amp section and survived so it is not live but am far more wary of the power supply.
My primitive way of experimenting in this instance would be to run the amp reasonably hard and touch the heat sinks to check temperature. Obviously safer would be to first unplug the power cord but for this type of power supply would, in general of course, the heat sinks be live and even if the power cord is removed would there be enough energy stored to shock?
I could measure with a multimeter but are these ac or dc and is the reference chassis ground or does the power supply float.
Any comments appreciated and please understand that I am at least smart enough not to kill myself.
Thanks, sp
Attachments
Yes you can get shocked in there, perhaps for many seconds after plug-out. One of those board is right on the power line.
Yes it WILL overheat delivering anything close to 300 Watts inside a closed box with no fan.
I suppose you have seen the review on the Berhenger site which gives a specific fan brand/model which is quieter.
Yes it WILL overheat delivering anything close to 300 Watts inside a closed box with no fan.
I suppose you have seen the review on the Berhenger site which gives a specific fan brand/model which is quieter.
Thanks PRR, I was hoping to respond sooner with good news.
I have found, unfortunately, that the 2 x 12V fans are already connected in series to a 12V supply so am looking at alternatives.
I have also made a temporary cover for the power supply so I don’t get electrocuted.
And disconnecting the fans, with the top lid removed, indicates that the amp module does need a bit of cooling but not much for a light load. The power supply heat sinks are just a little warm, although this is after a few minutes power off to avoid shock.
Cheers, sp
I have found, unfortunately, that the 2 x 12V fans are already connected in series to a 12V supply so am looking at alternatives.
I have also made a temporary cover for the power supply so I don’t get electrocuted.
And disconnecting the fans, with the top lid removed, indicates that the amp module does need a bit of cooling but not much for a light load. The power supply heat sinks are just a little warm, although this is after a few minutes power off to avoid shock.
Cheers, sp
do you still need the amp to be rack mounted? if not then then you could replace the fans with 2*120mm blowing out the top panel.
It's hard to believe that these fans add any neccesary value at all to this amp.
4x75W class D amplifier, amplifier board heatsink seems to be more than enough.
Rectifier heatsink in power supply also seems reasonable for consumption of such power. After all, there are probably ultrafast or hyperfast diodes. I don't have this Behringer model manuals but for example, IR21531 lamp ballast based power supply unit on very crappy Italian Parsek MarkBass amplifiers and ultrafast rectifier used in it ignores all conceivable laws of physics, has a piece of 50mm wide aluminum bar for cooling output rectifier, although the output power of this amplifier is almost 2x greater than the total power of this Behringer for 4 channels.
Seems to me from this picture that this Behringer model power supply has an order of magnitude better design that is, this heatsink on the rectifier is completely sufficient in normal operation without forced cooling, at least if everything works without problems.
It seems completely irrelevant to use these fans.
All of this should be able to work without fans, even because their position is illogical and seems like they just stirring warm air in there?
4x75W class D amplifier, amplifier board heatsink seems to be more than enough.
Rectifier heatsink in power supply also seems reasonable for consumption of such power. After all, there are probably ultrafast or hyperfast diodes. I don't have this Behringer model manuals but for example, IR21531 lamp ballast based power supply unit on very crappy Italian Parsek MarkBass amplifiers and ultrafast rectifier used in it ignores all conceivable laws of physics, has a piece of 50mm wide aluminum bar for cooling output rectifier, although the output power of this amplifier is almost 2x greater than the total power of this Behringer for 4 channels.
Seems to me from this picture that this Behringer model power supply has an order of magnitude better design that is, this heatsink on the rectifier is completely sufficient in normal operation without forced cooling, at least if everything works without problems.
It seems completely irrelevant to use these fans.
All of this should be able to work without fans, even because their position is illogical and seems like they just stirring warm air in there?
If I am correct, the amp should be equipped with thermal shutdown protection. Maybe for home use, no fans even with closed box would not be necessary. The fans are really noisy and annoying. I think I will just disconnect them and see what happens. Maybe putting it on its side with the PSU up would improve convection cooling.
Thanks for the replies.
overpower, your assessment is in my view spot on.
pelanj, I may have some news on the fan noise soon but have been distracted.
However, I am still experimenting based on my feeling that this amp offers rather good value for money.
sp
overpower, your assessment is in my view spot on.
pelanj, I may have some news on the fan noise soon but have been distracted.
However, I am still experimenting based on my feeling that this amp offers rather good value for money.
sp
In general there are not many problems with EPQ.
I have never repaired any of EPQ myself. From your picture, everything looks relatively decent. I'm guessing the amp side has some sort of TDA895x under the heatsink (x= 0 or 4, or something), that heatsink seems perfectly adequate for 2 chips, I've seen many TDA895x amps with much smaller heatsinks and they work very well even without fans.
If you look at Behringer iNuke 6000 from internet for example, they also have noisy fans, but in fact life has shown that these amps work without them and they are more powerful, 800-900 RMS W.
Although iNuke has a bunch of compromises but however, I have never had any of iNuke series amps on my desk with a problem on the amp side, they have some issues with power supply but overall considering cheap price that part is pretty good too. Behringer could have made this amplifier more better with addition of a few components and added a few euros to the price, then it would have been much better amp.
I have never repaired any of EPQ myself. From your picture, everything looks relatively decent. I'm guessing the amp side has some sort of TDA895x under the heatsink (x= 0 or 4, or something), that heatsink seems perfectly adequate for 2 chips, I've seen many TDA895x amps with much smaller heatsinks and they work very well even without fans.
If you look at Behringer iNuke 6000 from internet for example, they also have noisy fans, but in fact life has shown that these amps work without them and they are more powerful, 800-900 RMS W.
Although iNuke has a bunch of compromises but however, I have never had any of iNuke series amps on my desk with a problem on the amp side, they have some issues with power supply but overall considering cheap price that part is pretty good too. Behringer could have made this amplifier more better with addition of a few components and added a few euros to the price, then it would have been much better amp.
I have spent a lot of time on these fans but have now run the amp for days with them disconnected with no problem.
However this is without the top lid.
Will report back because imho they are excellent value and you could hardly build it yourself for less (down under at least).
overpower, I agree regarding Behringer, on the one hand providing value for money but on the other hand it seems to me they could have made a better product with just a few hours more spent on the design.
Cheers, sp
However this is without the top lid.
Will report back because imho they are excellent value and you could hardly build it yourself for less (down under at least).
overpower, I agree regarding Behringer, on the one hand providing value for money but on the other hand it seems to me they could have made a better product with just a few hours more spent on the design.
Cheers, sp
I believe nothing bad will happen also with the top cover closed either.
I'm still guessing but the amplifier is probably TDA895x and similarly, XH-M252 (for example: http://www.icstation.com/tda8954th-...tereo-amplifier-dual-chip-2x420w-p-12546.html ) module uses dual such class D amplifier chip TDA8954. I've done a lot of testing with this module, and despite relatively small passive heatsink, it doesn't get dangerously hot. Many sellers claim power of this module to be 2x400W, the real power would be somewhere around 150-160W per chip, so 2x150W and it doesn't heat up so much that it needs fans.
If you are in doubt, it is always possible to make a simple thermoregulator to control this fans, for example with an NTC or even a transistor that you attach to heatsink and which, according to increased temperature, it increases the voltage of the fans, i.e. at low power, fans would not be operated at maximum voltage, and therefore noise would be much less or such that can't hear it.
I'm still guessing but the amplifier is probably TDA895x and similarly, XH-M252 (for example: http://www.icstation.com/tda8954th-...tereo-amplifier-dual-chip-2x420w-p-12546.html ) module uses dual such class D amplifier chip TDA8954. I've done a lot of testing with this module, and despite relatively small passive heatsink, it doesn't get dangerously hot. Many sellers claim power of this module to be 2x400W, the real power would be somewhere around 150-160W per chip, so 2x150W and it doesn't heat up so much that it needs fans.
If you are in doubt, it is always possible to make a simple thermoregulator to control this fans, for example with an NTC or even a transistor that you attach to heatsink and which, according to increased temperature, it increases the voltage of the fans, i.e. at low power, fans would not be operated at maximum voltage, and therefore noise would be much less or such that can't hear it.
Thanks overpower, I had a bit of spare time so I had a play with the fans.
As mentioned the fans are 12V connected in series so approximately 6V on each I presume.
I connected 1 fan to a variable supply and it started and ran happily on about 4 to 4.5V and was noticeably quieter so I thought I would connect 2 in series and see if they would run off a lower voltage than 12.
Problem is that in series using my power supply only 1 fan turns even if I run it up to max V of about 14V. Even if I try to spin the stationary fan by hand it will not start up.
Any ideas it is beyond my knowledge I am just a solder monkey.
Thanks, sp
As mentioned the fans are 12V connected in series so approximately 6V on each I presume.
I connected 1 fan to a variable supply and it started and ran happily on about 4 to 4.5V and was noticeably quieter so I thought I would connect 2 in series and see if they would run off a lower voltage than 12.
Problem is that in series using my power supply only 1 fan turns even if I run it up to max V of about 14V. Even if I try to spin the stationary fan by hand it will not start up.
Any ideas it is beyond my knowledge I am just a solder monkey.
Thanks, sp
This is generally caused by the fan's internal controller, you would probably must change fans if you want to control them or if you want to run them with lowered supply then use independent Voltage regulators for fan supply, LM7808 or 7909 to get 8 or 9V and feed this to fans, this circuit is simple: http://www.circuitdiagram.org/12v-8v-converter-lm7808-regulator.html (for reference)
you can get very low cost DC-DC converters from ebay/aliexpress etc. I have used 24->6V in the past to run under voltage 12V fans in industrial equipment that only has 24V supply before. Some are so small you can solder them inline on the fan wire and just heatshrink round them.
I decided to take the risk and disconnected the fans. The amp is in an open rack (and top cover on). My speakers are pretty efficient, so the VU meter lights hardly turn on when listening at comfortable volume levels. No problems at all. I consider buying second one to power my 3-4 channel MEHs. There is a slight hiss, but that should go away with proper setup of the gains and I think it comes partially from the DSP.