Alesis MultiMix Hum Buzz solution.

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jokerone

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PROBLEM:
Alesis Multimix has a hum or buzz coming from one of the MIC channels or the Main Mix.
This was the case with my Alesis MultiMix 16 USB 2.0, but it seems to plague all of the new MultiMix mixers that use the same
Power circuit board with capacitors 2200uf 35v and 1000uf 35v.

After doing a bunch of research multiple people were claiming replacing these two capacitors would fix the problem. They were right.

PCB_01.webp

When I inspected the power board the 2200uf capacitor was budging at the top just like everybody else who has reported this problem.

The biggest 3 capacitors on the board were also glued down with a really tough rubber cement of some sort. I was worried I would break the board prying them off, but I finally got them off. Your board may or may not have the glue on them. It seems Alesis really didn’t want those capacitors to go anywhere.

I copied down a list of all the capacitors on my board (9-40-388), which seems identical to the 9-79-388 because it seems to fit all the newer (dark case) Alesis multimix mixers. Board ID : alesis xf1/6/7 power pcb


Capacitor List:
Capacitor Voltage Quantity
47uf 50v 2
100uf 100v 1
47uf 100v 2
47uf 25v 2
2200uf 35v 1
1000uf 35v 1
100uf 35v 2
330uf 25v 2


If this happens again, I’m going to replace all of the capacitors, but the only ones you probably need to replace are the 2200uf 35v and 1000uf 35v,
which is what I did with total success!

I replaced both of them with Panasonic FC series which are highend audio grade, and only cost about $1 each.
Total cost with shipping was less than $8.

1000uf35v.webp

I looked up the board and found this. They want $110 for it.
PCB, POWER ASSY - MM SERIES

I ordered the Panasonic FC series capacitors from Digikey.
DigiKey Electronics - Electronic Components Distributor


After I ordered the Panasonics, I found ones that are probably better for high end audio applications and about the same price.
Nichicon Muse (Premium)
Mouser Electronics - Distributore Componenti Elettronici

Mouser #: 647-UFW1V222MHD
Mfr. #: UFW1V222MHD
Desc.: Aluminum Electrolytic Capacitors - Leaded 35volts 2200uF 20%
Mouser #: 647-UFG1V102MHM
Mfr. #: UFG1V102MHM
Desc.: Aluminum Electrolytic Capacitors - Leaded 35volts 1000uF 85c 16x25 7.5LS

Another source is Parts ConneXion - The authority on hi-fi DIY parts and components
They stock the ELNA Silmic II Series capacitors, but I not the 2200uf 35v I needed.


VIDEO SUPPORT (HOW TO):
This video was a great help in putting things back together. Which I always seem to have a problem with. :D

Fixing hum in Alesis MultiMix - YouTube

I hope all of this helps.

thanks.
 
Last edited:
Good work man! :thumbs up: we've owned a Multimix 16 at work for about 4 years now and i guess we've been lucky as we've not had any problems with hum (although, with the gain cranked on any of the channels the noise goes up very quickly, but that wasn't totally surprising) but we have had a number of little problems (mainly cosmetic but the power supply also died and needed some resoldering to get it working again) and it's been battered about so much that i'm gonna make a note of this in case we experience this issue :)
 
It's nice to have this kind of info available.
My buddy owns one of these and I might be borrowing it to do some off the floor recordings of a full rock band. I doubt that he's actually used it enough to know if he has a problem.
Do you know if everyone with this problem reports the clip light in the FX section being on all the time?
 
how odd ..... I've been needing that exact cap (2200uF) for about a year for the power supply for my Soundcraft board and couldn't find the exact one.
Now I know where to get it ... yay!
 
dug dog said:
It's nice to have this kind of info available.
My buddy owns one of these and I might be borrowing it to do some off the floor recordings of a full rock band. I doubt that he's actually used it enough to know if he has a problem.
Do you know if everyone with this problem reports the clip light in the FX section being on all the time?
Click to expand...

I didn't have the clip light problem. My problem was pure audio. If I moved the sliders for any/all of the mic inputs the hum would be there and get louder as you increased volume. The old capacitors were rated for 2000 hours of use. The new ones are rating for 5000 and are highend audio grade, unlike the old ones.

I took photos of my setup before I started to pull the plugs on everything. It helped when putting it back together.
 
Lt. Bob said:
how odd ..... I've been needing that exact cap (2200uF) for about a year for the power supply for my Soundcraft board and couldn't find the exact one.
Now I know where to get it ... yay!
Click to expand...

Very cool. Glad to help. It took me a day of hunting to find these for that one. the 1000uf was pretty easy. I wouldn't buy on ebay, all of those are being shipped from China, and I was in China earlier this year. The amount of counterfeit crap for sale there is unbelievable and its flooding world markets as well. For something like this I would only buy from a trusted supplier. An example. My 14 year old daughter wanted to buy a present for her friend. While we were there, she bought a pair of Beats headphones for $7. Her friend was amazed, until she told her they were counterfeit, but she liked them just the same. Every shop in Shanghai and Beijing had the same knock-off crap.

PS, check the voltage. the 2200uf 50v were pretty easy to find, it was the 35v that was harder.
thanks
 
Justsomeguy said:
Good work man! :thumbs up: we've owned a Multimix 16 at work for about 4 years now and i guess we've been lucky as we've not had any problems with hum (although, with the gain cranked on any of the channels the noise goes up very quickly, but that wasn't totally surprising) but we have had a number of little problems (mainly cosmetic but the power supply also died and needed some resoldering to get it working again) and it's been battered about so much that i'm gonna make a note of this in case we experience this issue :)
Click to expand...


thanks.
 
jokerone said:
Very cool. Glad to help. It took me a day of hunting to find these for that one. the 1000uf was pretty easy. I wouldn't buy on ebay, all of those are being shipped from China, and I was in China earlier this year. The amount of counterfeit crap for sale there is unbelievable and its flooding world markets as well. For something like this I would only buy from a trusted supplier. An example. My 14 year old daughter wanted to buy a present for her friend. While we were there, she bought a pair of Beats headphones for $7. Her friend was amazed, until she told her they were counterfeit, but she liked them just the same. Every shop in Shanghai and Beijing had the same knock-off crap.

PS, check the voltage. the 2200uf 50v were pretty easy to find, it was the 35v that was harder.
thanks
Click to expand...
as long as it fits size wise it don't matter.
You can use a cap for a higher voltage capacity with no problem but I haven't even found one at 50 volts and 35v IS the one I need.
Thanks! .... I owe ya' something ....... some day I'm gonna tell that redhead that yes, yes she should go with ya'.
:D
 
Lt. Bob said:
as long as it fits size wise it don't matter.
You can use a cap for a higher voltage capacity with no problem but I haven't even found one at 50 volts and 35v IS the one I need.
Thanks! .... I owe ya' something ....... some day I'm gonna tell that redhead that yes, yes she should go with ya'.
:D
Click to expand...

During my research I read someone was having ripple problems with the larger voltage capacitor. I'm a software guy, not a hardware guy so I have no idea.
the redhead will be fine, just don't tell me wife. :D

Actually, A redhead would be nice, but if you would go to this link and listen to the song and give me an honest assessment of it. You won't hurt my feelings. Thanks!
https://homerecording.com/bbs/gener...city/dance-4-syria-contest-submission-353900/
 
Worked for me

Mine hummed and had a signal going to aux 1 with the clip led lit.

Replaced those caps and hum gone and led went out, Just need to check effect to see if it worked.

Funny, when I first turned it on after putting it together I though I forgot to plug something back in because is was so quite..

Thanks GREAT info ....
 
Temp rating of replacement caps

I am going to attempt this repair. Just curious: the 2200 uF and 1000 uF capacitors on my board are rated for 105 degrees. I noticed that the Nichicon caps suggested by jokerone are rated for 85 degrees - anyone have any problems with that since installation?

Also, i damaged one of the jumper connectors - pulled 1 wire out of the connector by accident when i was dissassembling to inspect the capacitors for bulging - anyone have any tips/suggestions on how to perform the repair of that jumper/connector?
 
Video

Hi,
I know this is an old thread but any chance anybody knows where to find that video from the original post since the link no longer works?

I know it is a long shot but would be appreciated

Thanks.
Steve
 
There are a couple of vids on Youtube that might help but I don't see the one that was originally linked. Check those others out but, I did archive the original 10 minute vid and could put it on Dropbox for you to download. It's about 56 megs.
 
Thanks, The videos that I found on u-tube do not show the dis-assembly and reassembly just where the problem is so the original would be appreciated.
 
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