Work? L, R RCA inputs -> 1 XLR out? - diyAudio
Go Back   Home > Forums > Source & Line > Analog Line Level

Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 14th May 2013, 08:36 PM   #1
diyAudio Member
 
Soldermizer's Avatar
 
Join Date: Feb 2012
Location: Tamper, FL, USA
Default RCA (L,R) inputs (pre-amp) = mono XLR output?

Does anyone know if this would work? I want to get a balanced (XLR) pre-amp the cheapest way possible. Is it possible to take a mono XLR input, amplify it via a standard unbalanced RCA stereo pre-amp, and then combine the outputs to a single XLR output? Only custom cables or connectors would be needed which is at my level of expertise

I realize I would need two preamps for stereo I already have two candidates to experiment upon.

Last edited by Soldermizer; 14th May 2013 at 08:54 PM.
  Reply With Quote
Old 14th May 2013, 09:30 PM   #2
diyAudio Member
 
indianajo's Avatar
 
Join Date: Jan 2010
Location: Jeffersonville, Indiana USA
Most preamps have a differential input, but they make it single ended by connecting the RCA ring to chassis ground. They tend to tie both left and right side signal returns to a common point which is also chassis ground. I turned my Herald RA88a mixer into differential input by putting rubber O-rings around the RCA jacks, cutting the RCA jack buss and rerouting the "ground" wires inside to actually use the op amp differential input. That, and some other things, cut the hum.
On the other hand, my Peavey CS800s amp, which has actual XLR inputs, makes less hum (slightly) if I hook it up with RCA to 1/4 phone plug cables instead of RCA one end (from the floated output of the mixer) and XLR on the other end. A couple of hours making up XLR ends on a coax cable were wasted. Hint. Don't buy SPC21418 XLR plugs. The inserts melt too easily and the shells are too small.
If your preamp has an op amp as an input, or has two transistors tied together at the emitter, one for feedback, you are 1/2 way there. Just some wiring details to make it a differential input. If your preamp is all hooked together with ribbon cables with surface mount part, forget anything I said. The RA88a was hand wiring (kit) to a single sided PWB, and leaded parts on the PWB.
__________________
Dynakit ST70, ST120, PAS2,Hammond H182(2 ea),H112,A100,10-82TC,Peavey CS800S,1.3K, SP2-XT's, T-300 HF Proj's, Steinway console, Herald RA88a mixer, Wurlitzer 4500, 4300

Last edited by indianajo; 14th May 2013 at 09:34 PM.
  Reply With Quote
Old 14th May 2013, 10:14 PM   #3
Loren42 is offline Loren42  United States
diyAudio Member
 
Join Date: Sep 2008
Location: "Space Coast" Florida, USA
The cheapest route would be adding two stages to the preamp. One that accepts a balanced signal in and and another that splits it into a low impedance balanced output.

The input receiver is the Texas Instruments INA134
The output IC I use is the Texas Instruments DRV134

Both ICs accurately manage differential signals with great accuracy and low noise/distortion. It is nearly impossible to get the same performance level with discrete components without very careful matching of components. These ICs make the job a piece of cake.

The only advantage to doing this is to accept devices that have differential outputs and to drive devices that have differential inputs.
  Reply With Quote
Old 15th May 2013, 05:18 PM   #4
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Some have reported this arrangement using B1 and DCB1 as the active elements.
There are probably many more reports doing similar.
__________________
regards Andrew T.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
New TPA3106D1 with XLR and RCA inputs for use in a very small speaker cabinet Yoshy Class D 3 19th September 2010 03:57 PM
Is it possible to connect both XLR and RCA inputs at the same time into an Aleph 5 Rony1 Pass Labs 7 21st March 2010 04:42 PM
XLR (maybe balanced) and RCA amp inputs rick57 Solid State 5 23rd November 2006 12:20 AM
Behringer DCX2496 XLR -> RCA solution wigginjs Digital Line Level 2 8th July 2005 10:03 PM
RCA -> XLR balanced line transmitter eRiCdWoNg Parts 15 30th December 2003 12:44 AM


New To Site? Need Help?

All times are GMT. The time now is 08:58 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2