Digidesign Mbox 1 - headphone sockets mod

[Whoops]

In the Mbox 1 there are 2 headphone jacks, a 1/4 (at the rear) and a mini jack (front) , they don't work at the same time since when you plug a jack in the 1/4 socket it cuts the feed to the mini jack.

Sometimes maybe it will be useful to be able to use both jacks at the same time, like if you need to plug 2 sets of headphones
If you want to do so, just open your mbox and solder 2 jumper wires in the 1/4 socket like is shown in the picture.

really simple

 

[Richon]

good!!!

now that you have it open, is there a way to use Just the AD/DA converters on the Mbox without going through the preamp (to use my green preamp)?

any good mods to it?

(I also have the "old" Mbox v.1)

 

[rattleyour]

Assuming this actually works:

http://www.gearslutz.com/board/low-end-theory/162071-how-do-i-bypass-preamps-built-into-mbox-1-a.html

 

[Whoops]

yes it actually works.

In the Mbox 1 bypassing the preamps is quite easy since it has inserts. You just go from your mic pre into the (unbalanced) insert return.

you can't do that with the Mbox 2 models, neither the 002 or 003 unfortunately.As far as I can tell.


I don't have the Mbox opened since I took the picture some time ago, But I can open it if you need any more info, or pictures.

it would be nice off course to have the insert return balanced so that we go from a balanced +4dbs preamp output to another balanced input, instead of going to a -10 unbalanced input.
Would it work just to stick a simple unbalancing circuit in there?

see if this one works, the Mbox only has USB1 voltages,  + - 5V, dont know if the TL072 or a 5532 would work with those.

 

[Richon]

it could be done, but I think there's to much to loose to go from +4 to -10dB...

Someone posted that "external preamp" -> "external AD/DA" -> Mbox SPDIF should be the right wait to go....  but I think is to much hasle

 

[NewYorkDave]

C'mon guys! Going from +4dBU balanced to -10dBV unbalanced is easy. Just use a good quality 10K:600 transformer.

 

[Whoops]

C'mon guys! Going from +4dBU balanced to -10dBV unbalanced is easy. Just use a good quality 10K:600 transformer.

Cool, what transformer would you recommend?


Going from the external preamp to a good AD converter then spdif to the Mbox is the best way to go definitely. I don't think its too much hassle , it depends on your needs, if you only need to record 1 or 2 simultaneously its a nice protools setup.

 

[Richon]

Now, is there a good A/D DIY project?  just for the fun of it?

 

[Whoops]

That would be nice . A dissected Lavry gold that you could build for 200 dolars!!!

 

[Svart]

What A/D IC is in the Mbox?  I bet it's just fine.  Hell, my 3k$ Alphalink uses AKM codecs, the same as used in computer motherboards and sound cards.  Most A/D boxes have marginal analog circuitry and low rails which lead to all of the regular sound problems.  Build the 9k or green pres and interface them to the Mbox A/D IC somehow and you'll have a kickass setup I bet.

 

[Whoops]

I dont really Know. I can open it and take pictures, but I dont know if I will be able to tel what is the A/D IC.

I know the Black Lion Audio, were doing some Mbox mods back in the day, they still perform the mods if you ask them.

Im sure the 5 volts rails of the USB power are the reason for people complaining about sound. But to be honest that device is just fine for what it is.

 

[barclaycon]

A couple of things.
First of all, it doesn't matter if the voltage from the USB is +5v. it can be jacked up to whatever is necessary. After all, the Mbox does supply +48v. phantom power !
The mic. amps on the Mbox 1 are possibly the worst I have ever heard. Quite what that did for Focusrite's reputation I don't know. But they sound THIN.

I would love to get hold of the schematic for the Mbox 1.
Does anyone have it ?

Apart from the mic. amps the Mbox works fine for me - both on my PC and laptop.
A nice cheap way of fiddling around with stuff without disturbing the main ProTools system.

 

[Svart]

crack it open, take HD pictures, we'll figure out how to get to the A/D with an external preamp.

;D

 

[Whoops]

Will do it as soon as I can.

Probably Friday.

 

[Silvas]

Any new findings on this?

 

[Whoops]

I'm really sorry, had to borrow my Mbox to a friend for some weeks. When I get it back I will take the photos and I will PM you to keep you up to date.

Thanks

 

[mrphotodude]

kubi, are you using indicator tubes like the em84 for a meter?

 

[Whoops]

??????????

 

[Whoops]

crack it open, take HD pictures, we'll figure out how to get to the A/D with an external preamp.

;D

Any new findings on this?

I finally had the opportunity of taking some HD pictures of the MBOX PCB and components.

I've posted them here:

http://twin-x.com/groupdiy/thumbnails.php?album=353


let me know if you need more pictures