# Adaptor for Musicomlab fx MKII? What I need???



## Salokin (Nov 10, 2008)

I recently received a used Musicomlab fx MKII but it wasn't coming with any adaptor.

I know you can power the FX MKII on the outlet 5 and 6 of the PP2+, and it will be the ultimate solution when my board will be set and ready, but for now I'd like to use it with an adaptor just to learn and make some tests too!

Yesterday I've found and adaptor that the output characteristics are:
9V AC,800mA.

On the website it says 400mA so 800mA would be okay I guess because it's more than what it needs. right! I just don't want to burn my new unit by plugging in it the wrong adaptor. Another thing that is bugging me a bit is the mention on the Website: Powered by 9VAC, regulated 12VDC.

And now I've just noticed that in the User Manual, it says that the MKII requires regulated 12V DC? I haven't seen anywhere "9VAC" written in the manual? I just have to know and be sure which characteristics do I need? 

9 VAC or 12V DC?

If it's 12V DC, Will l need to know if it's positive or negative center too?
Thanks for help on this, I'm really not an expert.


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## greco (Jul 15, 2007)

WOW...what a lot of confusing and conflicting information !!

Personally, I would contact the manufacturer directly (or one of their distributors)
and ask them for clarification and also about the polarity (i.e.,positive or negative center).

Cheers

Dave


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## Salokin (Nov 10, 2008)

Yeah, I'm waiting for an answer from Musicomlab support, probably will have the answer from them on Monday,
but how I see it is that you can power it 9VAC or 12VDC. Just need to know the Polarity if using 12VDC.

To be sure I'll wait to have the answer from Musicomlab but I'm kind of impatient to check out this unit!


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## Salokin (Nov 10, 2008)

Nice,
I've just received the answer from musicomlab, that was very fast,
nice customer support!

Here what they said if anyone needs to know:


If you have a EFX MkII (not MkIII), you have to use a regulated 12VDC
adapter over 300mA.Both center plus and minus are available to use for EFX.
Because EFX has rectifier circuit inside.
and you have to use linear type adapter (not SMPS type).


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## greco (Jul 15, 2007)

Great that you got the answer so quickly. 

*"Both center plus and minus are available to use for EFX.
Because EFX has rectifier circuit inside.
and you have to use linear type adapter (not SMPS type)."
*
Do you understand the above quote? 
Can you use _*either*_ a centre or minus plus ?

What is a linear type adapter?
What is a SMPS type adapter?
(I haven't googled either yet)

Cheers

Dave


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## Salokin (Nov 10, 2008)

I understand that you can use positive center (center Plus) and negative center(minus plus).One or the other.

The only thing I'm not sure is concerning Linear Type adaptor and SMPS type.. It' suppose that SMPS type adaptors
are the one for Europe but I'm not sure for the moment. 

I have a switching power adaptor of 1000mA that you can choose in between regulated 3VDC and 12VDC. You can also choose the center polarity but anyway I can use both polarity here. I can't confirm if it's a linear adaptor though? How can you know that?

Thanks!






greco said:


> Great that you got the answer so quickly.
> 
> *"Both center plus and minus are available to use for EFX.
> Because EFX has rectifier circuit inside.
> ...


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## mhammer (Nov 30, 2007)

I would gather that SMPS is a switched-mode power supply. Linear supply is the traditional transformer+diodes+smoothing capacitors. This implies that a One-Spot or Godlyke or any other adaptor that makes you think "An amp and a half from THAT little thing?" are off-limits. I gather the EFX Mk III will be confused by any potential HF clock signal riding on the DC.

Given what the EFX Mk III is, the digital portion runs off 5v internally for the control stuff, and uses 12v for any relays or whatnot. So, the underlying strategy is that one feeds in something higher than 5v, and it gets regulated down to 5v and 12v.

If one was to feed it 9VAC, there would be no ground contact as such, coming from the adaptor. Both contacts are equivalent. Feeding it a 12vdc adaptor, though, you would need one of the contacts to be ground and one positive. There are some pretty smart supply regulation schemes out there, but I have yet to see anything that would accept being fed any orientation/polarity and simply go "Oh, better flip that around". So you do need to be assured of polarity first, lest you burn out any protection diodes...or worse.

For pedals, or another device that switches between internal battery supply and external adaptor, one generally MUST use outside as pos and inside as ground, simply because of the way the jacks are designed. When there is no "power handoff", as such, it becomes the manufacturer's choice which orientation to use.

The most foolproof way to identify the orientation is to ask the manufacturer, but it would seem their best attempt at clarification is insufficient (the manual is no great shakes either). Failing that, what I'd do is pop the cover plate off, identify an obvious ground plane on the PCB (the connection that is common to all those send and receive jacks is a pretty decent place to start), and figure out, with a meter or continuity tester, whether that goes to the center pin on the adaptor jack. If it does, then you know you can use a standard Boss-type adaptor.

Does that answer your question?


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## greco (Jul 15, 2007)

Thanks mhammer...hope this helps the OP

Cheers

Dave


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## Salokin (Nov 10, 2008)

mhammer said:


> Does that answer your question?


Yes! Thanks for having taken the time to answer the question in details.
What I will do is go to a place where they'll be able to find the polarity of my efx MKII. I know a place close to where I am,
called Accès Electronic and I know they have all the necessary materiel to test devices.

Anyway Thanks Greco and Mahmmer for help!
I let you know when I have more details.

Cheers!


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## Salokin (Nov 10, 2008)

The Musicomlab efx MKII has a rectifier so that's why you can power it negative center or positive center.
You can use both without any problems.


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