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Ultra-High Performance Stereo RCA to True Balanced XLR Converter

orchardaudio

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All,

I have designed a stereo RCA (single-ended) to XLR (balanced) converter.

I will have both fully assembled and bare boards available.
Fully Assembled boards: 150 to 180 USD + shipping depending on interest
Bare boards: 12 to 18 USD + shipping depending on interest, see BOM in attachments.

Parts used are OPA1622 as initial buffer to OPA1632 for SE to balanced conversion.

Input impedance: is 47k
Output impedance: is 100 ohm.
Gain: 2.5V/V or 8dB (can easily be adjusted if you get the bare boards with resistor values)
Input Voltage: 9V
Onboard very low noise LDOs: LT3090 and LT3042

Please let me know if you are interested.

Thanks;
Leo
RCA_toXLR.JPG
 

Attachments

  • RCA_to_XLR_BOM_Rev1.0.zip
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Tom C

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This looks like two channel, correct?
 

Matias

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Very nice.
But also a multichannel option would be great for AVR pre-outs with insufficient volts for feeding power amps.
 
OP
orchardaudio

orchardaudio

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Very nice.
But also a multichannel option would be great for AVR pre-outs with insufficient volts for feeding power amps.

You can get as many of these as you need for multi channel, these are very small. and you can daisy chain the 9V power supply to all of them.
 

sergeauckland

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Interesting. Do you have a specification, especially for maximum output voltage and load driving capability. I use a number of RCA-XLR converters professionally, so am interested. I would also much prefer a 10 turn pot to set gain rather than changing resistors as trimming output levels is important.

S.
 
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orchardaudio

orchardaudio

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Interesting. Do you have a specification, especially for maximum output voltage and load driving capability. I use a number of RCA-XLR converters professionally, so am interested. I would also much prefer a 10 turn pot to set gain rather than changing resistors as trimming output levels is important.

S.
I have not measured them yet, but I don't even think my audio analyzer will be able to measure the true performance of this circuit as the specifications for these parts exceed the measurement capabilities of my APX-525.

It essentially going to be completely transparent. The output voltage is limited to about 20Vpp (7Vrms) before its starts clipping due to the power supplies.

The output current capability of the OPA1632 is 150mA, considering the 100ohm output impedance it can drive any load with no problem.

There is no pot on this version, maybe in the future. However I am sure you would be able to wire a pot in if you wanted to externally.
 

MakeMineVinyl

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All,

I have designed a stereo RCA (single-ended) to XLR (balanced) converter.

I will have both fully assembled and bare boards available.
Fully Assembled boards: 150 to 180 USD + shipping depending on interest
Bare boards: 12 to 18 USD + shipping depending on interest, see BOM in attachments.

Parts used are OPA1622 as initial buffer to OPA1632 for SE to balanced conversion.

Input impedance: is 47k
Output impedance: is 100 ohm.
Gain: 2.5V/V or 8dB (can easily be adjusted if you get the bare boards with resistor values)
Input Voltage: 9V
Onboard very low noise LDOs: LT3090 and LT3042

Please let me know if you are interested.

Thanks;
Leo
View attachment 198044
Schematic?
 
OP
orchardaudio

orchardaudio

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Can now be pre-ordered with 20%$ off, coupon code is "rcaxlr"
 

airmail

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I'd like these so I can run balanced a fully balanced setup with a 3700 - have you got cases in mind that these boards will drop into? Preferable want to run 9 channels.
 
OP
orchardaudio

orchardaudio

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I'd like these so I can run balanced a fully balanced setup with a 3700 - have you got cases in mind that these boards will drop into? Preferable want to run 9 channels.
I am in the process of designing cases for these now. The cases will be stereo (2ch) so you will need 5 of them to run 9 channels.

The cases will be similar to the PecanPi Streamer ones, but much smaller.
 

airmail

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I can live with that, I'd look at building a little box for them - just can't be bothered messing about with PCBs.
 
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orchardaudio

orchardaudio

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For those interested in the DIY version you can purchase it on the website using code "rcaxlr" and get 20% off.
 
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orchardaudio

orchardaudio

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Images of the converter.
RCA_to_XLR_Module_Back_1920.jpg


RCA_to_XLR_Module_Front_1920.jpg


Some initial measurements:
Signal to Noise Ratio.jpg


Dashed lines are AP-525 in loopback mode. 22.4kHz BW.
THD+N Ratio vs Measured Level.JPG


Dashed lines are AP-525 in loopback mode. 22.4kHz BW.
SMPTE Ratio vs Measured Level.JPG



Gain and Phase.jpg


10kHz Square wave (1.2MHz BW)
Square Wave.JPG



Multitone.JPG


For some measurements looks like I am limited by the performance of my audio analyzer.
 
Last edited:
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