Rolls MB15b ProMatch Balanced/Unbalanced Converter 3.5mm/RCA/XLR

Brand:|Model: MB15b
The MB15b ProMatch is a veritable Swiss army knife for the audio pro or enthusiast. It converts consumer level stereo RCA signals to balanced XLR professional line level, and back.
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List Price$90.00
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Part # 245-1062
  • Stereo direct box
  • L + R RCA to L + R XLR
  • Stereo level control for each channel
  • Works as stereo balanced line level control
  • 1/8" headphone level to line level adapter

Product Details

Rolls MB15b ProMatch Balanced/Unbalanced Converter 3.5mm/RCA/XLR

One side of the MB15b (labeled 1) has two XLR inputs and stereo RCA outputs. The other side (labeled 2) has stereo RCA inputs and two XLR outputs. Each side has a stereo level control, and an LED indicates that power is applied to the unit. An additional benefit of the MB15b is that it will act as a balanced XLR line level control. By adding a stereo pair jumper between the four RCA jacks (connecting ins to outs), the two level controls may be inserted into any balanced XLR line. AC power adapter included. Made in the USA.

For more than two decades, those in the know have turned to Rolls for the highest quality, reliability, and value. Rolls is an innovative company specializing in domestically manufactured signal interface accessories, mixers, amplifiers, and processors for the audio professional.

Specifications: • Dimensions: • 4.15" x 2.46" x 1.55" • Weight: 1 lb.

  • Mixer TypeAnalog
  • XLR Mic Inputs< 6
Rolls MB15b ProMatch Balanced/Unbalanced Converter 3.5mm/RCA/XLR
  • BrandRolls
  • ModelMB15b
  • Part Number245-1062
  • UPC675889001501
  • Product CategoryLine Mixers
  • Unit of MeasureEA
  • Product Rating
    (7 Reviews)
  • Weight1.2 lbs.
  • California Prop 65

    Warning: California residents only. Please note per Proposition 65 that this product may contain chemicals known to the State of California to cause cancer and birth defects or other reproductive harm.

View similar products to the Rolls MB15b ProMatch Balanced/Unbalanced Converter 3.5mm/RCA/XLR
in the Line Mixers product category.


Rolls MB15b ProMatch Balanced/Unbalanced Converter 3.5mm/RCA/XLR
Rolls MB15b ProMatch Balanced/Unbalanced Converter 3.5mm/RCA/XLR is rated 4.5714 out of 5 by 7.
Rated 5 out of 5 by from Next LevelI was advised not to purchase this because my xls 2500 had rca connections, but I just had to know, so I pulled the trigger. MAN OH MAN!!!! This little box my subwoofer system to a performance level that I had only dreamed of. I only have the amp up 6 clicks, and my 2 Ultimax 15's are producing ungodly amounts of bass
Date published: 2014-12-24
Rated 3 out of 5 by from Love the capabilities. But It's so noisy.I've only used it a couple of times thus far. Unless I'm playing it loud, the modulating 60 hz hum is overwhelming. Even when it's cranked, I still notice the noise. Does anybody know if it'll run on 12 volts so I can see if running on a battery helps it? If this box could run as quiet as the rest of my system, I'd give it 5 stars.
Date published: 2014-05-31
Rated 5 out of 5 by from unbalanced to balanced +4 out = yesI have an old Crest FA901 amp that I wanted to use for in-wall passive subs, one in the living room, one in the bar. Results were blah, which forced me to read through the data sheet and begin to understand what input level that amp was looking for. This product is small and worked perfectly to boost the preamp output of my consumer AVR to something that woke the Crest up. Dramatic difference, and from what I can tell adds no noise to the system.
Date published: 2014-05-14
Rated 4 out of 5 by from returned itemChanged mine on order and returned it. Parts Express that no you for your great return policies and no hassle returns.
Date published: 2014-01-24
Rated 5 out of 5 by from Pro Audio in Home SystemI have 3 Crown XLS 1000 pushing 6 18" FI Car Audio IB subs. The output was dismal even with gains turned all the way up on amps and on my Denon receiver. I started thinking about the pre-out voltage from my receiver and figured this was the problem.I purchased the Rolls MB15b, hooked it up, turned the gain to half way and BAM! There was the bass I was looking for.I now have amp gains at 90% and my Denon bass gains on -2db only using 3 of the 6 18's.If you are using pro audio amps in your home system, this is a MUST HAVE item. Don't think twice, just order it!
Date published: 2013-10-10
Rated 5 out of 5 by from Great Audio ConverterWe use this gadget in our Function Venue to convert IPOD or Laptop sound from RCA to XLR so we can run the sound through our pro in house sound system. Easy to use and does the job perfectly! Love the product and it is so hard to find a user friendly alternative so this is my second one.
Date published: 2013-09-16
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Product Q&A

Get your questions answered from other customers
who own this product or have experience with it.
If your question requires design or troubleshooting information,
please email  for a prompt reply.
Rolls MB15b ProMatch Balanced/Unbalanced Converter 3.5mm/RCA/XLR

Would this be able to output a mono XLR signal if I were to input a mono RCA signal?

Asked by: Jthan12
Answered by: MattP
Date published: 2015-06-24

How to hook it up to my Onkyo txnr828 in pre outs, I have a crownxls1500,and 1000 in my 7.2 hooked up now with just xls cable from amp to receiver, what other cables do I need and how to I hook it up thanks, my speakers for my pre-outs fronts Polk rtia9

Asked by: mystro1
This requires standard RCA subwoofer cables from the receiver to this Promatch, then male to female XLR cables from the Promatch to the Crown amplifiers.
Answered by: MattP
Date published: 2015-01-06

Is boosting the dB level on my AVR the same thing as using one of these? Is the rolls promatch better then the art cleanbox or vice versa?

Asked by: Farro
This will balance the signal as well as boosting up the level. I do not really have a preference between this and the cleanbox as both do a very good job when using balanced amps and processors on unbalanced gear.
Answered by: Chrisf
Date published: 2014-10-03

Can this be used to match Reciever LIne Outputs to Pro Amp?

I was hoping to use a Crown Amp (XLS 2500) to power a couple subs. Crown rates full power at 1.4v input whereas the maximum output from Yamaha RX820A is 1.0v. Can this unit be used to get maximum output from the Crown amps?
Asked by: Auburn 77 81
This item is very good quality, but you may need a "real" preamp to get to "Professional 1.4 Volts RMS". I will include suggestions below. The slam dunk, is a low cost mixer that will take whatever your Yamaha delivers--even a -20db signal and convert it to as high as +20 db [if needed]. I have a few of these Behringer mixers--Real Pro/Low Cost/Quiet. And they look cool!! They are available with 1/4" phone outs or 1/4" + XLR outputs. There is also stereo RCA inputs-1/4" phone and XLR inputs.
Answered by: Joe from San Francisco
Date published: 2013-10-22
  • 2015-12-01T07:38CST
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