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I came across a few very handy-looking RapcoHorizon DBBLOXF DI's... but they have a female XLR jack. I have panel mount male XLR jacks. Can I convert these over so I can toss them in the goody bag? Is it a simple matter of changing the jack? The innards look very simple, just a small transformer between 1/4" and XLR jacks. I have a handful of DI's, but you can never have too many. Plus, these are tiny. I could toss them into the acoustic guitarist's guitar cases for emergency spares.

I'd love to use these, but we actually got them for free because our electric guitarist works at Rapco's warehouse and they had a housecleaning event to free up old space.

Curtybob wrote:I came across a few very handy-looking RapcoHorizon DBBLOXF DI's... but they have a female XLR jack. I have panel mount male XLR jacks. Can I convert these over so I can toss them in the goody bag? Is it a simple matter of changing the jack? The innards look very simple, just a small transformer between 1/4" and XLR jacks. I have a handful of DI's, but you can never have too many. Plus, these are tiny. I could toss them into the acoustic guitarist's guitar cases for emergency spares.

I'd love to use these, but we actually got them for free because our electric guitarist works at Rapco's warehouse and they had a housecleaning event to free up old space.

Hold the phone there pardner!

That is exactly opposite of what you want. That box is designed to convert low impedance to high impedance - that's why the connection is wired that way....also why they are being cleaned out. It is very rare to convert a low impedance signal to a high impedance signal. Maybe for re-amping in the studio, but certainly not for what you want.

The way he was talking, they just had a room of odd product that caught the eye of management. They decided to have the employees clean out the space, and gave them approval to keep what they wanted since it was destined for the dumpsters.

He got a ton of cables, a large assortment of fully assembled rack mount snake faceplates, a ton of cables, a prototype digital snake component (he thought it was a usb recording interface),a ton of cables, and a bunch of random stuff. Oh... and he got a ton of cables. Dont know if I mentioned that.

And yeah, I looked these DI's up... just kinda hoped that the guts were fairly universal and non-directional. Oh well. No biggie. Just seemed awfully handy if they could be repurposed.

They might be non-directional....but I would doubt it. You could always use a gender changer and test it out. If it works - there ya' go.

But I would think it's probably used for hooking up a LOz mic to a HIz input.

What's the model number?

The only model number I can find is the DBBLOXF on the side.

According to the Rapco site, the two boxes are identical except for the XLR connector. Transformer is a 6:1 turns ratio with a 24db loss or gain, depending which way you use it. Reflected input impedance is about 21.5K ohm when plugged into a Low Z 600 ohm mic preamp input. http://www.rapcohorizon.com/p-366-dbblox.aspx

Swap out the XLR female for a male, and you're back to a standard DI box configuration.
The female version was apparently for matching a low Z mic to a hi Z preamp input, or used to drive a guitar amp input on a long balanced line as was suggested.

Years ago I built up some passive DI boxes with both male and female parallel connectors using Beyer transformers for exactly that purpose.
In the studio, I could mic up a guitar amp in an iso booth, and have the guitarist playing while sitting beside me in the control room. I simply plugged his guitar into one DI box, and then drove a balanced line to the iso booth via the control room patchbay, connected to another DI box plugged into the amp input in the booth.

Awesome! Thanks!

i'd be interested in some of those faceplates if your friend was considering moving them....

The only thing is they seem to be missing the all-too-important ground lift switch and it doesn't appear there's enough space to install one.

Right. Space is definitely at a premium inside that housing. I guess I could work a few wooden extensions to house the xlr jack in order to free up enough room for a mini toggle...

I can talk to him about the plates, but he has plans for all but a few.

Because you have zero$$ invested so far, for about $20.00 you could buy a Hammond box and move the works into a bigger enclosure. Add the switch for ground lift; you could even install a male and female XLR allowing it to be used both directions.

byacey wrote:Because you have zero$$ invested so far, for about $20.00 you could buy a Hammond box and move the works into a bigger enclosure. Add the switch for ground lift; you could even install a male and female XLR allowing it to be used both directions.

And for about $35, you can buy a real direct box without all the extra work and expense that already has the correct connector and a ground lift.

Oh yeah. All that is definitely doable. The main reason I even want these is that I can toss them into the guitarists acoustic case so they are on hand for emergencies. I have a pretty decent collection of proper DI's. These are just very handy backups that can stow away in an already crowded acoustic guitar case (or two, actually).

Bruce Weldy wrote:And for about $35...

$35??!! We're not all made of money (ok, maybe you lot are, but I'm not - yet!!) $35 could buy me a fair few genuine speakons, or XLRs or another 3 sets of plans (and $1.05 to add to the BB fund!). I've had far too many "oh, it's only £xx" on this journey, I've easily spent £1000 ($1712 at the time of posting!) on small odds and sods like this I know all about buy once, but if you ain't bought it in the first place, then there is certainly no need for the tears. And if you DO get it working, then it's all good - I thought this was a DIY forum after all

EDIT:

Bruce Weldy wrote:you can buy a real direct box without all the extra work and expense

Expense, you say??.... well that kind of buggers up my argument (and my plans to get more plans)