Loudspeakers - Converting unbalanced RCA to Balanced XLR

[skienblack]

I am trying to convert a unbalanced RCA output from a DJ mixer to a balanced output of XLR so I can run it to a set of power speakers. My fear with just going with 1/4" is the interference that will get picked up on the run to the speakers.

My initial thought was to use a DI box, but I have read that many cheaper models will cause more of a hum than without them. What would my best bet be? The run to the speakers could be anywhere from 25' to 50' worth of cable.

[rwhealey]

DBRC-2A

That's what you need...

A passive DI shouldn't ever cause a hum, even if it is cheap. I wouldn't run 50' of unbalanced cable.

[SHARYNF]

The potential problem is that usually the di is setup to take a line level signal and balance it but also attenuate it to mic level, this COULD be a problem ( if for example you are using Mackie SRM450 or something like these, then they DO have the ability to take a mic level in
an alternative is to look at a converter, they are all levels of quality

here is a link to a cheap one

Amazon.com: SAMSON TECHNOLOGIES S-CONVERT BALANCED/ UNBALANCED CONVERTER STEREO: Electronics

sharyn

[howlingwolf487]

Since you are dealing with a DJ, I highly recommend you use a high-quality DI with the ability to pad down the signal by a good bit, as they (the DJ) will absolutely slam your mixer's inputs with as much output as their mixers will give them. I recommend this one. Sure, it's a little pricey, BUT you will get much use out of it and it will be extremely unlikely to die on you when you need it. Look into some inline pads, also.

Maybe this DJ will prove me wrong...

[skienblack]

The potential problem is that usually the di is setup to take a line level signal and balance it but also attenuate it to mic level, this COULD be a problem ( if for example you are using Mackie SRM450 or something like these, then they DO have the ability to take a mic level in
an alternative is to look at a converter, they are all levels of quality

here is a link to a cheap one

Amazon.com: SAMSON TECHNOLOGIES S-CONVERT BALANCED/ UNBALANCED CONVERTER STEREO: Electronics

sharyn

I was going to go with that one, but I read a review for it on a sight selling them saying it was picking up a hum. Though based on a previous post I don't know how this is possible?

Since you are dealing with a DJ, I highly recommend you use a high-quality DI with the ability to pad down the signal by a good bit, as they (the DJ) will absolutely slam your mixer's inputs with as much output as their mixers will give them. I recommend this one. Sure, it's a little pricey, BUT you will get much use out of it and it will be extremely unlikely to die on you when you need it. Look into some inline pads, also.

Maybe this DJ will prove me wrong...

We are actually going to be running from the DJ mixer through the DI box into the speakers. We most likely will be using some speakers like the JBL Eon 15" G2 (which do take mic level input). Though I think I would rather run it at line level to reduce any degradation of the signal? As for doing damage to the box and the speakers, I am working with the DJ while he is paying for the equipment rental/purchase so I am not worried about him or another DJ doing damage.

[SHARYNF]

It could be picking up hum if the placement of the converter was near a power line since these usually use transformers.

here is an alternative at the next price point

Amazon.com: Rolls MB35 Converter 2 Way, Stereo RCA to Stereo XLR,USB Input Capability, 3.5 mm Input Jack: Electronics

here is a lower price link for the samson b stock unit

Samson S-Convert*::*Effect Processors*::*Signal Processing & Effects*::*Studio & Recording*::*DJ Equipment - Turntables, DJ Packages, CD Players and Mixers at Audiolines.com

here is a link to a decent tech review

Samson S-Convert (alt. to ART Cleanbox) - Home Theater Systems - Electronics and Forum - HomeTheaterShack

Personally I'd go with the Samson for your use, the Radial is nice but definitely pricey

sharyn

[rwhealey]

The EWI (audiopile.net) DI I posted is rock solid and has a choice of pads- you can still run things at line level, or mic if you want to. I have one sitting in front of me right now. Unless you're set on getting the Radial because of the brand name, the EWI will do everything you need it to.

[howlingwolf487]

Though I think I would rather run it at line level to reduce any degradation of the signal?

Yes, line level would be the appropriate setting, but if you're running any length over 20ft-30ft, you would need to balance the signal so no degradation occurs. You could use a DI (which will balance the line AND drop the signal to mic level) or you could use an isolation transformer (which would balance the line and keep it at whatever "level" it's at currently, -10dBV, I'm guessing).

As for doing damage to the box and the speakers, I am working with the DJ while he is paying for the equipment rental/purchase so I am not worried about him or another DJ doing damage.

GET IT IN WRITING!!! Get the DJ to write down the he/she will pay for any and all damages incurred to the equipment he is using for the gig. Otherwise, you may find yourself with a lighter wallet...

[museav]

You could convert the mixer output to balanced audio for the run but that may provide no isolation, which can be a factor since it is quite common to have to run the powered speakers off a different circuit than the mixer. Using a DI is possible and can provide transformer isolation but also forces you to run a mic level signal to the speakers. You could also run the signal unbalanced and put a good input transformer at the speaker end, that should work just fine and also provide transformer isolation.

I think that padding down of the signal related to doing so before the interface box, or at least prior to any circuitry in the box. You are still dealing with overloading the input of the box and possibly at a lower level than the speaker input, so you'd have to pad the signal prior to the DI or interface circuitry to get any benefit and that still won't address any clipping from the mixer.

Unless you need the USB connectivity, the Rolls MB15b would probably be a less expensive option to the MB35. If you want something that comes more from the pro rather than consumer/MI end, look at Henry Engineering, however the price does reflect the higher quality.

You may be paying for more than the name and reputation with the Radial Engineering AV2, there can be differences in the transformers and other components used that aren't readily apparent. Since no model was noted, I assume it is the EWI FDB-202 being referenced. I would be interested to know what is actually in the FDB-202, you have to go to Audiopile's site to get any data on it as EWI seems to provide no product specs or data on their web site. However, the FDB-202 would likely be quite acceptable for this application, although you'd then be dealing with mic level signals to the speakers.

[skienblack]

The potential problem is that usually the di is setup to take a line level signal and balance it but also attenuate it to mic level, this COULD be a problem ( if for example you are using Mackie SRM450 or something like these, then they DO have the ability to take a mic level in
an alternative is to look at a converter, they are all levels of quality

here is a link to a cheap one

Amazon.com: SAMSON TECHNOLOGIES S-CONVERT BALANCED/ UNBALANCED CONVERTER STEREO: Electronics

sharyn

Unless you need the USB connectivity, the Rolls MB15b would probably be a less expensive option to the MB35. If you want something that comes more from the pro rather than consumer/MI end, look at Henry Engineering, however the price does reflect the higher quality.

I am torn between these two DI boxes. Of the two could anyone speak to the quality? They are both relatively cheap which is good. Or would either be as good as the other? Thanks

GET IT IN WRITING!!! Get the DJ to write down the he/she will pay for any and all damages incurred to the equipment he is using for the gig. Otherwise, you may find yourself with a lighter wallet...

They will be purchasing/renting the equipment themselves with my advice and my assistance in setting it up and running it.

[museav]

I am torn between these two DI boxes. Of the two could anyone speak to the quality? They are both relatively cheap which is good. Or would either be as good as the other?

I don't know the ART box that well, I do know that all the Henry Engineering products I have used have been well built. Either would likely work in your application, however a possible factor is that the recessed level controls might keep others from playing with things once you have set the levels.