Is anything wrong with my Anthem MCA-525?

[Andrein]

Hi,

I bought MCA 525 recently and the first thing i noticed is a noticable pop in speakers when switching amp on and off. This happens even if nothing is connected to the amp. After that i measured dc voltage on speaker output and noticed that when i switch amp on, dc voltage goes up to about 0.5-0.6v dc and then goes down to 10-20mv. When I switch the amp off, there is another pop and this time speaker cones go forward and stay in that position for about 2 seconds, then go back. But even after switching amp off i can see about 0.5v DC in speaker outputs for quite a long time (at least some minutes).

Anthem dealer says there is nothing to worry about. But I don't see the same with my Yamaha a860 and Monolith 5 while doing the same test.

My question is is that normal and safe for speakers? I got ProAc 148s front and 118s surround.

 

[slipperybidness]

@TLS Guy what you think?

That sounds like trouble to me! I sure as heck would not be connecting any pricey speakers to an amp or AVR that showed that type of behavior.

Did you purchase this from an authorized dealer?

I see that the Anthem web site clearly shows "30 Day $ Back Guarantee".

If this was my gear, I would probably take it to the dealer where I purchased it, tell them that I understand that it "may not be a problem", but I am still "not comfortable using this on my $$$ speakers".

 

[Andrein]

I bought this from the dealer... They just told be to try auto-on mode instead of explicit on. Will try later today without speakers connected. My main concern is not the pops on on/off but the fact that dc levels are quite high and they don't go away quickly.

 

[PENG]

I bought this from the dealer... They just told be to try auto-on mode instead of explicit on. Will try later today without speakers connected. My main concern is not the pops on on/off but the fact that dc levels are quite high and they don't go away quickly.

I have a MCA amplifier that never make such noise. Power amps should only make such pop when it is turned on first, followed by the source such as a preamp. If you turn on the source first, followed by he pramp, and then turn on the power amp last, there should be no audible pops unless your speakers are really sensitive.

Regarding the voltage, it's probably normal for the MCA amp because mine behaves similarly. My Halo and Bryston do register much lower readings. My MCA also took a long time to discharge the output capacitors.

You should ask the dealer to demo another unit to see if it would make the same noise. If not, then you can easily justify bring yours back and let him hear it and then ask for a replacement.

 

[Andrein]

I have a MCA amplifier that never make such noise. Power amps should only make such pop when it is turned on first, followed by the source such as a preamp. Regarding the voltage, it's probably normal for the MCA amp because mine behaves similarly. My Halo and Bryston do register much lower readings. My MCA also took a long time to discharge the output capacitors.

You should ask the dealer to demo another unit to see if it make the pop too. If not, then you can easily justify bring yours back and let him hear it.

It might be that your speakers are not as sensitive as mine or if you use in auto-on mode (when front button is constantly pressed, but the amp activates when it detects input signal). I was using explicit on/off up to now. Going to check auto on later today. Dealer said in their show room they have the same sound when the amp initially switched on. But their amp had been in auto on mode so they did not see that sound before.

Do you speakers feel ok with MCA amp? Should i try to add huge capacitors like 2x10000uf to get rid of that pop?

 

[slipperybidness]

It might be that your speakers are not as sensitive as mine or if you use in auto-on mode (when front button is constantly pressed, but the amp activates when it detects input signal). I was using explicit on/off up to now. Going to check auto on later today. Dealer said in their show room they have the same sound when the amp initially switched on. But their amp had been in auto on mode so they did not see that sound before.

Do you speakers feel ok with MCA amp? Should i try to add huge capacitors like 2x10000uf to get rid of that pop?

Adding caps ain't gonna get rid of pops. It is the in-rush current that charges the caps that makes these noises. Adding caps may even make the problem worse on turn-on, as you would add more in-rush current too.

This thing is new, right? I sure as heck would not be expecting to have to mod a new amp under warranty.

 

[slipperybidness]

I have a MCA amplifier that never make such noise. Power amps should only make such pop when it is turned on first, followed by the source such as a preamp. If you turn on the source first, followed by he pramp, and then turn on the power amp last, there should be no audible pops unless your speakers are really sensitive.

Regarding the voltage, it's probably normal for the MCA amp because mine behaves similarly. My Halo and Bryston do register much lower readings. My MCA also took a long time to discharge the output capacitors.

You should ask the dealer to demo another unit to see if it would make the same noise. If not, then you can easily justify bring yours back and let him hear it and then ask for a replacement.

Just for clarification--I don't think your amp actually has OUTPUT Caps, right? That would mean caps past the output transistors?

I think you may be referring to the Power Supply Filter Caps? I suppose those could be seen as the "power supply output caps".

 

[Andrein]

Just for clarification--I don't think your amp actually has OUTPUT Caps, right? That would mean caps past the output transistors?

I think you may be referring to the Power Supply Filter Caps? I suppose those could be seen as the "power supply output caps".

I meant capacitors to get rid of DC voltage in speakers. Saw some suggestions when you put 2 of electolytic capacitors + to + and put in between amp and speaker on one of the wires.

 

[Andrein]

btw those pops can be heard in bass drivers only. So i suspect speaker crossover caps doing exactly this job here.

 

[PENG]

It might be that your speakers are not as sensitive as mine or if you use in auto-on mode (when front button is constantly pressed, but the amp activates when it detects input signal). I was using explicit on/off up to now. Going to check auto on later today. Dealer said in their show room they have the same sound when the amp initially switched on. But their amp had been in auto on mode so they did not see that sound before.

Do you speakers feel ok with MCA amp? Should i try to add huge capacitors like 2x10000uf to get rid of that pop?

You are correct, mine is set to auto. I just tried it in manual multiple times, still no pops. Try turning on all your sources (BDP, PC DAC etc), then the preamp, wait 10 seconds and then turn on the power amp.

My MCA20 has been powering my veritas V2.3i for probably around 5 years, yes they "feel ok" for sure.

 

[Andrein]

You are correct, mine is set to auto. I just tried it in manual multiple times, still no pops. Try turning on all your sources (BDP, PC DAC etc), then the preamp, wait 10 seconds and then turn on the power amp.

My MCA20 has been powering my veritas V2.3i for probably around 5 years, yes they "feel ok" for sure.

Can i ask you while all input devices off to measure DC voltage on front speaker output. During switching amp on and off and after off for some time. With speaker connected and without. In auto on an manual. Sorry probably asking a lot. I need to decide what to do with this amp.

 

[slipperybidness]

Can i ask you while all input devices off to measure DC voltage on front speaker output. During switching amp on and off and after off for some time. With speaker connected and without. In auto on an manual. Sorry probably asking a lot. I need to decide what to do with this amp.

I'm curious, are you 100% certain that you have DC on the outputs?

Did you use a DC Volt meter to measure this? Or did you use an o-scope?

DC on speaker outputs is BAD!
https://electronics.stackexchange.com/questions/233230/why-are-dc-signals-bad-for-loud-speakers

 

[PENG]

Just for clarification--I don't think your amp actually has OUTPUT Caps, right? That would mean caps past the output transistors?

I think you may be referring to the Power Supply Filter Caps? I suppose those could be seen as the "power supply output caps".

I hope not, but it does take forever for the output voltage to decay. To get rid of the residual voltage down to a few mV I had to short out the terminals for a few seconds. It behaves like one with output capacitor coupling and without any isolating relays. My other amps, even the Halo/Parasound don't behave this way.

 

[slipperybidness]

I hope not, but it does take forever for the output voltage to decay. To get rid of the residual voltage down to a few mV I had to short out the terminals for a few seconds. It behaves like one with output capacitor coupling and without any isolating relays. My other amps, even the Halo/Parasound don't behave this way.

OK, may be then.

Dunno, I never really jacked with any of this, never had any problems, on commercial gear.

Of course, for DIY gear you need to check that you don't have some serious design flaw or something mis-connected, BEFORE you hook up your speakers.

 

[lovinthehd]

I'd return it. Why put up with such?

 

[Andrein]

I used digital voltmeter in dc mode. This amp is actually 3rd one. I have replacement which behaves like first one. The one in showroom did the same. That is why i am thinking maybe it is normal? They asked me to check in auto mode. Will do that today.

 

[lovinthehd]

I used digital voltmeter in dc mode. This amp is actually 3rd one. I have replacement which behaves like first one. The one in showroom did the same. That is why i am thinking maybe it is normal? They asked me to check in auto mode. Will do that today.

You must like this amp a lot?

 

[Andrein]

Just could not find any true class ab amp in uk for less than less than 3500£. 5 chan. Tried emotiva xpa5 gen 3. Did not like it at all. Got a good deal for this with 0proc loan over 3y

 

[lovinthehd]

Just could not find any true class ab amp in uk for less than less than 3500£. 5 chan. Tried emotiva xpa5 gen 3. Did not like it at all. Got a good deal for this with 0proc loan over 3y

What didn't you like about the Emotiva that the Anthem resolves?

 

[Andrein]

Emotiva sounds worse than my yamaha a860. No clarity, instruments not separated. Just a mess. Even my wife when came asked what happened. Checked on all the same songs.