Extron XPA 1002 Plus Amplifier Review

[morethinkingcapacityneede]

ahaha I didn't think I had pissed off the two ebay sellers so much that they would implant nefarious "ticking devices" into the stuff they shipped me, but you never know! Perhaps the aim was to cause moderate annoyance, since the ticking is annoyingly audible a few metres when no music is playing.

 

[acoustic1]

Hi there. I'm wondering if anyone has heard a ticking noise from their units when powered on?

Hi,
I've bought 3 of these used from eBay - one is silent, one makes a sort of whine when idle, and the third makes the ticking noise.
The ticking seems to be coming from the capacitor circled in this pic. I've not had the lid off the other one yet to see where the whine is coming from.
Planning on replacing the cap when I get round to ordering a replacement.

It hasn't exploded yet.

 

[gegegege]

How did you pinpoint the issue to that capacitor? Is it cracked already?

 

[acoustic1]

No, it looks fine, but you can tell by listening close to it and the ticking sound changes/reduces as you poke the capacitor. I've ordered some replacements (X1/Y1 ceramic safety capacitors) and i'll let you know how successful it is.

 

[morethinkingcapacityneede]

No, it looks fine, but you can tell by listening close to it and the ticking sound changes/reduces as you poke the capacitor. I've ordered some replacements (X1/Y1 ceramic safety capacitors) and i'll let you know how successful it is.

So, I checked the two units I have, and the sound seems to be coming from the same place. I discussed this with an electronics friend of mine, and their hypothesis is that the Y1 cap is acting as a transducer (since they are slightly piezoelectric) rather than being the source of the noise itself. Saying that, replacing those could help with the sound levels, even if the underlying source is still there. It'd be really interesting to see the situation after the re-cap.

You mentioned that the slight whine disappears under load, I guess that means the clicking doesn't? Do you have an idea of what the load was? Was it above 50%?

 

[acoustic1]

I think your friend might be right. I replaced the cap in the ticking amp and it made no difference at all! Big waste of time - it wasn't as easy a job as I thought, those caps do not want to desolder!

I had the lid off the whining amp too. It's not really a whine but a very rapid ticking coming from, you guessed it, the capacitor.
The whine is always there, even with the amp at full whack, you just can't hear it over the music. Same with the ticking one.

So unless anyone can shed some light on the cause of this problem, it looks like a noisy amp is going to be a risk when you buy one of these.

 

[Doodski]

I think your friend might be right. I replaced the cap in the ticking amp and it made no difference at all! Big waste of time - it wasn't as easy a job as I thought, those caps do not want to desolder!

I had the lid off the whining amp too. It's not really a whine but a very rapid ticking coming from, you guessed it, the capacitor.
The whine is always there, even with the amp at full whack, you just can't hear it over the music. Same with the ticking one.

So unless anyone can shed some light on the cause of this problem, it looks like a noisy amp is going to be a risk when you buy one of these.

I just dropped into this thread and I don't want to review it's succession. Can you please give a me a updated and fresh review of the issue with your amp?

 

[acoustic1]

Basically my xpa 1002 amps (one of them is a plus) work fine, but make a low level ticking noise at all times, which is audible in a quiet room. It appears to be coming from the X1/Y1 capacitor and has continued despite replacing the cap.

 

[Doodski]

Basically my xpa 1002 amps (one of them is a plus) work fine, but make a low level ticking noise at all times, which is audible in a quiet room. It appears to be coming from the X1/Y1 capacitor and has continued despite replacing the cap.

Do you have a schematic diagram for this circuitry?

 

[acoustic1]

No, I've not found anything online.

 

[Doodski]

Basically my xpa 1002 amps (one of them is a plus) work fine, but make a low level ticking noise at all times, which is audible in a quiet room. It appears to be coming from the X1/Y1 capacitor and has continued despite replacing the cap.

Is this full time ticking noise from the physical capacitor package(s) or is it in the audio signal stream?

 

[acoustic1]

Is this full time ticking noise from the physical capacitor package(s) or is it in the audio signal stream?

It's from the capacitor package itself. There's nothing that shouldn't be there in the audio output (nothing I can hear anyway).

 

[Doodski]

It's from the capacitor package itself. There's nothing that shouldn't be there in the audio output (nothing I can hear anyway).

Hmmz... So it's a mechanical noise emitted by the capacitor package itself. The cap is smoothing or shunting power to ground. and>>> Before more. I need to know from your comment of:
It appears to be coming from the X1/Y1 capacitor and has continued despite replacing the cap.
Do you have images or diagrams of this PCB region and parts locations?

 

[NoxMorbis]

Found a picture:

View attachment 217052

It is the nice blue one. There is a common ground and dual differential inputs. I just desoldered the ends of two XLR cables and then screwed them in there with common ground.

These don't bother me all all. Pretty cool. Probably can find adapters, too?

 

[acoustic1]

Hmmz... So it's a mechanical noise emitted by the capacitor package itself. The cap is smoothing or shunting power to ground. and>>> Before more. I need to know from your comment of:
It appears to be coming from the X1/Y1 capacitor and has continued despite replacing the cap.
Do you have images or diagrams of this PCB region and parts locations?

Yep, take a look at post #122 - the photo shows the cap in question

 

[Doodski]

Yep, take a look at post #122 - the photo shows the cap in question

That blue disc component you circled appears to be a varistor. I'm pretty sure it is. I'll repost the pic so we have it easily accessible. Can you get identifying numbers from the blue component?

 

[acoustic1]

That blue disc component you circled appears to be a varistor. I'm pretty sure it is. I'll repost the pic so we have it easily accessible. Can you get identifying numbers from the blue component?

Zoomed in pic here...

X1/Y1 ratings shown. 472 = 4.7nF

 

[Doodski]

Zoomed in pic here...View attachment 281611
X1/Y1 ratings shown. 472 = 4.7nF

OK it is in the family of a Class-X and Class-Y safety capacitor.
These safety capacitors are also known by other names, including EMI/RFI suppression capacitors and AC line filter safety capacitors. (EMI stands for electromagnetic interference and RFI stands for radio-frequency interference; RFI is simply higher-frequency EMI.)

I have seen these in various stuff although I've never replaced one. They seem to be very reliable devices.
Due to the operational parameter of the X-Y safety caps they are difficult to test other than a Ohms and capacitance check and visually to inspect for burn marks and pin holes caused by failure of the device.

Safety Capacitors First: Class-X and Class-Y Capacitors - Technical Articles

Learn about Class-X and Class-Y capacitors, where they are used, and why they are referred to as

www.allaboutcircuits.com

 

[acoustic1]

I've discovered a fair bit of mention on the internet about ceramic capacitors in general making noise due to the piezo-electric effect, e.g:

Most ceramic capacitor dielectrics show piezo-electric effect, which causes them to vibrate with the applied voltage. If that voltage has an audio frequency the vibrations may be audible.

So, whatever is causing the capacitor to sing in the Extron (which seems to be quite common), the question is, is there a way to get rid of it? Could one way be to replace the ceramic cap with an equivalent film cap (same value and also X1 rated)? Would a film cap perform as well at EMI suppression duties - which I assume this ceramic cap is for?

 

[morethinkingcapacityneede]

In terms of eliminating the source of the noise, it might be worth replacing some of the other caps on the unit which may have aged, In particular, the caps highlighted in red below. If that does not work, the use of appropriate resin (the stuff that is used in the area highlighted in blue) might dampen the sound.