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In need of a Power Supply for a Alesis Multimix 8 USB (18V) (Will pay)

I was just given the Alesis Multimix 8 USB but my friend had accidentally thrown out the power supply with some other old electronics. As it would turn out, this is very hard to find. There are no after-market power supplies made, as far as I can tell. The specs are 18V 500 mA and here is a picture of what I need:
 

If anyone out there has this kind of power supply I will gladly pay what I can. I don't have a lot of money, but just let me know what sounds good to you. or if you know where I can get one that will work I would greatly appreciate being pointed in the right direction.

quickest way to get a response for anyone who has one they can sell is to e-mail me at thomaspatton2010@yahoo.com

Thank you for anyone who can help.

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Profile picture for user redcondurango

redcondurango Fri, 06/07/2019 - 03:39


Better late than never. There are still plenty of these kicking around and they offer some nice bang for your buck. Should you find one without its power supply unit never fear - here is the solution. The ebay reference for the three pin adapter was - 1Set M16 2/3/5/6/8Pins Screw Type Electrical Aviation Plug Socket Connector 400V. It will more likely than not come from the far east. Choose the 3 pin - obviously. See the image below for how to wire it up. There is a jumper between the two live positions, which is where the cable with the grey stripe is soldered. See the grey jumper . One position powers the phantom and the other the unit o coz there's only one power line you need to jump it round to the x 2 position for phantom power to microphones. Phantom on/off is on the front of the unit. The wall wart is also available on ebay - ALTO PRO ZMX52 MIXER 18V AC POWER ADAPTOR/SUPPLY/TRANSFORMER (KC AC-1800500) from poweradaptorsuk. Just search up the specs. I cut the end off the wall wart and soldered it up as per the image. It works fine. Watch out for surges to your speakers when switching on and off. Fortunately my monitors have a power up delay feature. Not sure if that surge is anything to do with the mod or the unit, which isn't earthed, seeing as there are only two wires. Go figure? The unit works though which is better than the dead unit which arrived on ebay minus its original psu which are nowhere available. Don't let anyone tell you this takes power via USB. Its old school 18V x 2 not 5V DC.

Profile picture for user Boswell

Boswell Fri, 07/31/2020 - 05:35

I've can't find any wall-wart type of transformer with a UK plug and an 18-0-18 secondary, but there are plenty of open-frame or encapsulated units. Try starting with Farnell Components. As an example, they have an encapsulated series with power ratings from 4VA up to 52VA.

To get a rough required VA rating, look at the rating plate on your official 18-0-18 transformer and multiply its maximum output current in Amps by 40. If it's specified in Watts, use the Watts figure plus 15%.

Profile picture for user alebro

alebro Fri, 07/31/2020 - 19:30

That's very useful information for the Multimix 12, and I might use it so thank you. I think some wires have been crossed though.

@Lee2020 is looking for a power supply for Multimix 6 FX, which reportedly is specced as 18.5 VAC at 700 mA (see this post)

Looking at the power supply that ended up being used for a Multimix 8 FX I suspect the same supply wired up as described would work for the Multimix 6 FC even though it's not quite a match. Parts of that post quoted here -

redcondurango, post: 461219, member: 51607 wrote:

The wall wart is also available on ebay - ALTO PRO ZMX52 MIXER 18V AC POWER ADAPTOR/SUPPLY/TRANSFORMER (KC AC-1800500) from poweradaptorsuk. Just search up the specs. I cut the end off the wall wart and soldered it up as per the image. It works fine... Its old school 18V x 2.

Profile picture for user Lee2020

Lee2020 Fri, 03/26/2021 - 14:17

redcondurango, post: 461219, member: 51607 wrote:
 
Better late than never. There are still plenty of these kicking around and they offer some nice bang for your buck. Should you find one without its power supply unit never fear - here is the solution. The ebay reference for the three pin adapter was - 1Set M16 2/3/5/6/8Pins Screw Type Electrical Aviation Plug Socket Connector 400V. It will more likely than not come from the far east. Choose the 3 pin - obviously. See the image below for how to wire it up. There is a jumper between the two live positions, which is where the cable with the grey stripe is soldered. See the grey jumper . One position powers the phantom and the other the unit o coz there's only one power line you need to jump it round to the x 2 position for phantom power to microphones. Phantom on/off is on the front of the unit. The wall wart is also available on ebay - ALTO PRO ZMX52 MIXER 18V AC POWER ADAPTOR/SUPPLY/TRANSFORMER (KC AC-1800500) from poweradaptorsuk. Just search up the specs. I cut the end off the wall wart and soldered it up as per the image. It works fine. Watch out for surges to your speakers when switching on and off. Fortunately my monitors have a power up delay feature. Not sure if that surge is anything to do with the mod or the unit, which isn't earthed, seeing as there are only two wires. Go figure? The unit works though which is better than the dead unit which arrived on ebay minus its original psu which are nowhere available. Don't let anyone tell you this takes power via USB. Its old school 18V x 2 not 5V DC.  

Hi there mate I've soldered a replacement power pack up and bridged the positive like shown but for some reason when i switch the mixer on it stays on full clip without any music playing through it and when i do plug in sound get nothing any ideas what this could be

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Profile picture for user alebro

alebro Tue, 08/04/2020 - 06:59

Lee2020, post: 465126, member: 51989 wrote: The more i thought about it though i know the original transformer has two 9v feeds from it but if i wired up a 18v laptop power pack and bridged the right two connections that go into back of mixer then it should work or would it pop the mixer

Have you measured it? Does it have 9 V on 2 pins and 0 V on the other?

Profile picture for user Boswell

Boswell Tue, 08/04/2020 - 08:09

I think we're getting confused between the Multimix 8 and the Multimix 6FX power adaptors. They are both dealt with in this thread.

According to the user manuals, the Multimix 6FX needs a single 17.5V AC input at 700mA (18V AC would be OK). This is probably used inside the mixer with one lead taken to chassis ground and the other serving two half-wave rectifiers for the internal + and - rails.

The Multimix 8 USB FX needs two separate 18V AC inputs, each at 320mA. It doesn't say in the manual, but Alebro's meter measurements in post #22 shows that these are used as 18-0-18. These probably feed a bridge rectifier to get the + and - rails with the input centre tap (0V) taken to chassis ground.

The implication of these figures is that, with a single 18VAC supply, the 6FX is likely to work, but the 8 USB FX is unlikely to work in an acceptable fashion, even if a centre-tap were wired or artificially created. A pair of 18V AC wall-wart supplies could be used to make an 18-0-18 V AC supply, provided they were wired so that the phasing on the secondaries was correct.

Profile picture for user alebro

alebro Tue, 08/04/2020 - 08:33

Just to confirm, my readings were for the adaptor for Multimix 12, which uses a transformer of 2 18 V 1000mA windings with a total output of 36 VA

Someone used this 18v 9VA AC/AC for Multimix 8 - link (details are in the post here), seems it would also work for Multimix 6 but using a 18 V DC is not ever going to be a good way of doing it.

Profile picture for user Boswell

Boswell Sat, 03/27/2021 - 03:08

This is a Multimix 6FX, right? These need a 17.5V a.c. 700mA supply. 18V a.c. would be OK, as we have been through in the preceding posts in this thread.

Assuming your mixer is still in a working state, you could get the effect you describe if you mistakenly used a d.c. output supply rather than an a.c. output one. What exactly does the label on your supply say, particularly if it uses the d.c. symbol (a stretched equals sign) or a.c. symbol (a stretched equals sign with a wavy top line)?

Profile picture for user Kurt Foster

Kurt Foster Thu, 04/04/2013 - 19:18

did you try a search of Google? it took me less than 1 minute to find [="http://www.instrumentalparts.com/almu8usb20mu.html"]THIS[/]="http://www.instrumentalparts.com/almu8usb20mu.html"]THIS[/].

[[url=http://="http://www.instrumentalparts.com/tf57033202ul.html"]POWER ADAPTER, 18*2VAC @ 1000mA, 110V[/]="http://www.instrumentalparts.com/tf57033202ul.html"]POWER ADAPTER, 18*2VAC @ 1000mA, 110V[/]
Regular price: $45.00
Sale price: $45.00

McMurphy Fri, 04/05/2013 - 15:25

Well there you go... exactly what you need.

On the other hand, it's no big deal to make your own power supply. All you need is a 110-24 V transformer, rated for 1.5/2 amps. In-line fuse and power switch. A bridge rectifier. A couple of large filter capacitors and an National Semiconductor, Texas Instrument, etc., 18 V regulator rated at least at 1 amp or more. And then you have a power supply costing about $25. You build it into an aluminum project box. Everything available at RadioShack.

Frequently it's hard to find specialized connectors for these power supplies to your mixer. Sometimes it requires a modification to a 4 or 5 pin, XLR connector which are much easier to find in comparison to some of those bizarre Taiwanese connectors. 4 pin XLR's were regularly used for 12 V power supply connectors for video cameras. Pin 1, is ground and Pin 4, was 12 V of positive DC. 2 & 3 were not utilized. Sometimes you find these on other mixers with ground, +48, +15, -15.

The only thing you have to find out is whether it required 18 V of DC or 18 V of AC? One will be the lucky and the other will take it out forever LOL. And I'm wondering how they obtained +48 for the Phantom power? So they are likely using a DC to DC up converter? So I really question that rating of 18 V? Maybe you should pick up a manual that includes a schematic? They can be helpful.

McMurphy

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Boswell Sun, 04/07/2013 - 11:39

The Multimix 8 USB only needs a.c. power (at 18.5V 700mA), as the rectifiers, regulators and smoothing capacitors are built into the unit.

If you design your mixer to take low-voltage a.c. power rather than d.c., it's easy to use voltage-multiplying techniques to get the 48V phantom power rail. The required current is only a few mA.

The mixer unit would probably work on 18V d.c. input, but there would be no phantom power.

PS I would snap up that power unit from Instrumental Parts while it's still in the sale and before it goes back to its normal price.

McMurphy Sun, 04/07/2013 - 15:30

Yeah Boswell, I checked the specs on that mixer power supply.

So it only requires a simple power transformer to convert 110 V AC to 18 V AC and you'll be up and running. No worry about polarity of the 18 V supply side because it's AC.

Assuming that the power supply has plenty of current to deliver, the internal power supply circuitry may also include DC to DC up-converters to create 48 V DC, low current, for the Phantom power needed for condenser microphones. These DC to DC up-converters have come into play and become quite popular in recent years more so than in the past. It's now all on a microscopic chip. I would be surprised if that mixer does not offer Phantom power. Even if it only works off of an 18 V supply.

Of course it's always desirable to have the company supplied unit. Thankfully, this kind of simple AC supply, only requires a simple transformer and the connectors you need. These transformers are available from companies like Newark Electronics, Digi-Key and others. This is a typical off-the-shelf readily available power supply transformer. You're going to pay a heftier fee for the factory supply. You don't need to. This is as simple as screwing in a lightbulb. No kidding.

McMurphy

Profile picture for user Lee2020

Lee2020 Wed, 07/15/2020 - 06:50

In this picture the wire with white line is this the postive wire only asking as my power pack broke for my alesis multimix 6 fx but i have a few laptop power packs with adjustable voltage settings so wanting to wire one of them up to the original power connector socket just wanting to 100% before soldering and testing

Profile picture for user Kurt Foster

Kurt Foster Sun, 04/07/2013 - 16:36

On the other hand, it's no big deal to make your own power supply. All you need is a 110-24 V transformer, rated for 1.5/2 amps. In-line fuse and power switch. A bridge rectifier. A couple of large filter capacitors and an National Semiconductor, Texas Instrument, etc., 18 V regulator rated at least at 1 amp or more. And then you have a power supply costing about $25. You build it into an aluminum project box. Everything available at RadioShack.

Frequently it's hard to find specialized connectors for these power supplies to your mixer. Sometimes it requires a modification to a 4 or 5 pin, XLR connector which are much easier to find in comparison to some of those bizarre Taiwanese connectors. 4 pin XLR's were regularly used for 12 V power supply connectors for video cameras. Pin 1, is ground and Pin 4, was 12 V of positive DC. 2 & 3 were not utilized. Sometimes you find these on other mixers with ground, +48, +15, -15.

your correct if you are all set up with a workbench and tools but not everyone is.

ok so i get in the car drive 10 miles round trip to the radio shack (cause it's 5 miles up the road and 5 miles back)... i dick around finding a parking spot, buy the parts and ohh don't forget a soldering pencil, flux and solder because i don't have that stuff already ...

then i go home and i go to put the parts together but i have to drill holes in the box so i get back in the car and i drive 10 miles round trip to home depot (cause it's 5 miles up the road and 5 miles back) and buy a drill and bits ..get back home and spend 2 or 3 hours putting it all together then i have to mickey mouse the connector on the mixer ... oops another drill bit ... back to home depot (another 10 miles) ... finally i get it all done and it works (maybe) or it fries the mixer (perhaps, because i really don't know what f i'm doing) but if it works it still looks like crud and is kludgy ... yeha i saved what? 20 bucks ... ohh but i drove 30 miles, spent 10 bucks on gas and and 25 bucks on parts and it took me 10 hours ....but wow i saved 10 dollars! ohhh i forgot ... the drill and bits cost me another 40 bucks and the soldering supplies were another $20... duh

i know you mean well but sometimes you diy guys crack me up. for me, to not have to go through all that 45 bucks is cheap .. like the man said it's on sale .. get one while it's still 45 bucks the price is going to go up to 45 bucks soon!

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Boswell Wed, 07/15/2020 - 08:04

Lee2020, post: 464923, member: 51989 wrote: In this picture the wire with white line is this the postive wire only asking as my power pack broke for my alesis multimix 6 fx but i have a few laptop power packs with adjustable voltage settings so wanting to wire one of them up to the original power connector socket just wanting to 100% before soldering and testing

The Alesis spec for the Multimix 6FX power supply is 18.5 VAC at 700 mA. Note that it's a transformer only, providing an a.c. output, so no +ve and -ve.

What are the specs of the laptop PSUs you have?

x