Alesis RA150 emit mystic high frequent sound from the unit itself

[SoundIS]

Alesis RA150 emit mystic high frequent sound from the unit itself

Hello,

As soon I turned on brand new Alesis RA150 Amplifier - it begin to emit
a some kind high frequency sound - from INSIDE of the unit. NOT from the speakers.
I can clearly hear that high frequency tone from about 2 meters distance.

Could that be a power supply related? The sound is really annoying, especially if
because I'm using it as a reference amplifier in quiet recording studio environment.

What can be wrong? I don't know it this should be so? I really hope not...

I would really appreciate any help.

Thanks in advance.

[J M Fahey]

Is any thing connected to it?
Unplug all inputs and outputs.
Volume controls on "0".
Still there?
Does any "clip" light turn on?
Or any VU meter (if it has one) indicates some audio level?
If it has a fan, isn't it squeaking or hitting some debris?
Worst case, if it's brand new, send it back; it's an excellent Studio amp and should be absolutely noiseless.

[SoundIS]

Is any thing connected to it?
Unplug all inputs and outputs.
Volume controls on "0".
Still there?
Does any "clip" light turn on?
Or any VU meter (if it has one) indicates some audio level?
If it has a fan, isn't it squeaking or hitting some debris?
Worst case, if it's brand new, send it back; it's an excellent Studio amp and should be absolutely noiseless.

Thanks for your answer.

I have tried different scenarios - with cables attached & without, low volume, high volume etc. Otherwise that error sound everything else function properly. I don't think that model use fan, it should be fan-less.

Can it have enything to do with how good or bad grounded electrical power it receive from socket?

?

[Jazz P Bass]

Is the noise a very high frequency?
About as high as a dog whistle.
Being that the unit weighs 15 lbs. & would have to say that they are using a switching power supply.
This particular unit does not have a fan.
There may be a bad inductor coil (bad solder) on the switch mode power supply.
The inductors filter out the very high frequency switching noise.

[SoundIS]

Is the noise a very high frequency?
About as high as a dog whistle.
Being that the unit weighs 15 lbs. & would have to say that they are using a switching power supply.
This particular unit does not have a fan.
There may be a bad inductor coil (bad solder) on the switch mode power supply.
The inductors filter out the very high frequency switching noise.

I have done some measurements. The mystic tone correspond G2 and/or G3 on piano. In other words 98Hz and 196Hz. Maybe that can give some info?

Thanks.

[J M Fahey]

Then you have been misleading us from the beginning; 98 and 196 Hz is not high frequency in anybody's book.
Post an MP3.

PS: from Alesis RA150 own site page:

Cool, quiet operation.

Designed for studio use, each RA series amp incorporates advanced convection cooling for heat dissipation. The result is long, stable operation unaffected by heat-related complications, without the added distraction and annoyance of fan cooling. And eliminating the danger of losing hard-to- hear details due to noisy amp performance.

Just send it back.

[SoundIS]

Then you have been misleading us from the beginning; 98 and 196 Hz is not high frequency in anybody's book.
Post an MP3.

PS: from Alesis RA150 own site page:


Just send it back.

Well the problem is that it keeps at G but several octave layered: G2,G3,G4 etc at once. That makes confusion. I will keep you updated.

Thanks for assistance.

[J M Fahey]

Then it's "buzz"
I suspect it's something as stupid as vibrating transformer laminations or something similar.
Of course, until you find it, the correct name is "annoying".
I find it to be "mechanical" in nature and transformer related.
If you can get a doctor's estethoscope (no kidding) it may help you.
If possible, "they" should take care of it, specially on new equipment.
Good luck.

[SoundIS]

Then it's "buzz"
I suspect it's something as stupid as vibrating transformer laminations or something similar.
Of course, until you find it, the correct name is "annoying".
I find it to be "mechanical" in nature and transformer related.
If you can get a doctor's estethoscope (no kidding) it may help you.
If possible, "they" should take care of it, specially on new equipment.
Good luck.

Hello,

This may be deeper that I thought from the beginning. I got a crackles from the speakers connected to RA150 on regular basis, as a loop, once per second - even if the RA150 volume is turned down to 0.

Also, crackles 'play' among my movements on the screen. The interesting part is that crackles is NOT present when listening on headphones.

Ground loop syndrome??

Cheers.

[J M Fahey]

You have gremlins in your amp.
1) try your amp somewhere else.
Not only in another room, but preferably in another house, to check whether it's something that comes through the mains.
2) use another amplifier at your studio, even if a home musical centre or similar.
If you can borrow a stereo power amp, from some soundman friend or DJ or similar, even better.
Do you still have the same symptoms?
3) anyway, I respectfully insist on my first suggestion, send it back to the shop, don't take on your own a repair work that "they" should take care of.
As a curiosity, where are you writing from?
Maybe that explains your refusal to use the factory guarantee.
Good luck.
PS: there's nothing *so* special about that amplifier, it's the same as many other good amps, you might just switch to another brand/model.
PS2: I*hope* you are not using some kind of stabilizer or power conditioner with it, or somewhere in your studio, are you?

[SoundIS]

You have gremlins in your amp.
1) try your amp somewhere else.
Not only in another room, but preferably in another house, to check whether it's something that comes through the mains.
2) use another amplifier at your studio, even if a home musical centre or similar.
If you can borrow a stereo power amp, from some soundman friend or DJ or similar, even better.
Do you still have the same symptoms?
3) anyway, I respectfully insist on my first suggestion, send it back to the shop, don't take on your own a repair work that "they" should take care of.
As a curiosity, where are you writing from?
Maybe that explains your refusal to use the factory guarantee.
Good luck.
PS: there's nothing *so* special about that amplifier, it's the same as many other good amps, you might just switch to another brand/model.
PS2: I*hope* you are not using some kind of stabilizer or power conditioner with it, or somewhere in your studio, are you?

Hello,

I have eliminated clicks and cracks that appears every second in loop - buy replacing ALL grounded power cables with Ungrounded. Smart?

No I'm not using any kind of stabilizer.

But that annoying G2 sound is still present. Not so loud as before but it is there. Does that means that it is still problem with amp? I'm writing from Sweden and I don't have problems to send it back. But first I must be sure what is going on. Also, I have very tight dead line for a current project and I can't afford 10-15 days without amp

Beside that, when I lay down my hand on the unit top cover, I can feel very subtle and fast vibrations. Someone suggested that it can be a related...?

I will try your all other suggestion just to be sure!

[J M Fahey]

replacing ALL grounded power cables with Ungrounded. Smart?

Almost.
You should have lifted all but ONE.
Which one to re-place?
You test it; one position will be slightly better than others.
Now to the buzzing sound.
*If* you are so much pressed by your schedule *and* you feel qualified to do it *and* don't mind voiding the warranty, *carefully* open it (there's 230V AC there) and use your best ear to find the vibration.
You can use a chopstick with one end pressed on the bone around your ear and the other end touching the transformer (the main suspect) or different points in the chassis; obviously with the amp "on" and in a very silent room.
This is the poor man's version of a stethoscope which is the real tool I recommend.
Invaluable to find buzzes, rattles, etc.
I guess the transformer was not well potted (or at all), and some lamination is vibrating, or it is too close to some iron chassis part, causing the same, or you have a rattling nut or washer.
If the buzz dissappears when the cover off, then this is the culprit, place a small piece of spongy rubber between it and the transformer.

[SoundIS]

Almost.
You should have lifted all but ONE.
Which one to re-place?
You test it; one position will be slightly better than others.
Now to the buzzing sound.
*If* you are so much pressed by your schedule *and* you feel qualified to do it *and* don't mind voiding the warranty, *carefully* open it (there's 230V AC there) and use your best ear to find the vibration.
You can use a chopstick with one end pressed on the bone around your ear and the other end touching the transformer (the main suspect) or different points in the chassis; obviously with the amp "on" and in a very silent room.
This is the poor man's version of a stethoscope which is the real tool I recommend.
Invaluable to find buzzes, rattles, etc.
I guess the transformer was not well potted (or at all), and some lamination is vibrating, or it is too close to some iron chassis part, causing the same, or you have a rattling nut or washer.
If the buzz dissappears when the cover off, then this is the culprit, place a small piece of spongy rubber between it and the transformer.

They told me that I will void the warranty if open unit by myself. So I decide to send it back for replacement. They will send back a brand new Alesis RA-150

I must say that, apart from the problem with it, it really delivers tone that I'm comfortable with. I'm the type of guy that loves 'honestly' in the sound. That is one of the reason I'm using RA-150 - to fire up my golden Yamaha NS10s

Thank you for your help in investigating and diagnostic the problem. I couldn't make it without your help. That's for sure.

Cheers!

[J M Fahey]

Good, a sensible decision, let *them* handle their problem.
Good luck.