DIY - add TRS Balanced Inputs and Outputs with ground lift

Started by ron45, December 15, 2015, 04:03:23 PM

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ron45

A box that may or may not possibly contain an isolation circuit and a balanced input  from PCM 91... or guitar synth. So make that 4 quarter inch stereo input jacks, these would be summed to a stereo pair for each two inputs and exit as mini stereo female jacks. Unless of course that is a poor design idea. I have a buddy who is retired from China Lake test center. He worked mostly in electronics. He could draw a schematic for me.

I have a Vox tonelab EX which I am content with sonicly because I can input tracks  via the mini stereo input. However, it is total dogshit PCB mounted and failing. I knew these were junk going in and babied them that jack like crazy. It never leaves my studio and I'm still having to figure out how to fix that jack solidly to the  pcb. Maybe some goo that's non conductive?? Shoe Goo or silicone??? Epoxy the kind you mix. I don't know how electrically inert any of those are.

Thanks

Ron

I'd like to be able to feed  the balanced out's of the PCM91or the synth output into the tonelab's failing mini stereo jack. That is if I can fix it. Any suggestions for this. I'm not really an electronics guy but I know how to soldier and follow simple circuits so long as I know how the components are supposed to behave.

I welcome any suggestions on the pcb fix and how to do the summing box [for lack of a better term]
3 Eastman Archtops, Ibanez PM100, Custom built tweed Princeton 34 watt 12" spkr Roland HPD15  2 Avalon 737sp  8buss 16 track Tascam Mixer  Lexicon PCM91 reverb deity Digital Performer Mac pro, Kurzweil K2500, GR 1 GR 30 GK3 on Eastman 910  64 fender jazz bass bought new  AKG 712  CAD VS2 tube mic

admin

#1
I accomplish that with a Rolls PM-351

http://c3.zzounds.com/media/M_PM351-be1a7e3b14d325bf9e93b92c4259cb2d.pdf

http://www.amazon.com/rolls-PM351-Personal-Monitor-Station/dp/B001032IDS
http://www.manualslib.com/manual/315183/Rolls-Pm351.html?page=3#manual
QuotePM351 Personal Monitor Station.
This unit mixes a microphone signal with a 1/4" Tip-Ring-Sleeve stereo
or mono instrument level signal and a 1/4" TRS stereo or mono monitor
signal. The Mic Input and Thru jacks have a switchable ground lift, as do
the balanced XLR Instrument Outputs. The instrument input connects to
two independent XLR balanced outputs via real audio transformers.
The PM351 is designed for performers who want to monitor their own
sounds, such as their vocals and instruments, with the main mix via
headphones or earphones. It's very popular with drummers who need
to mix a click track with a monitor signal. Church choir singers love the
PM351 to monitor their voices over the musicians.
The PM351 is shipped with an external AC adapter.

or the Rolls MX122 - MiniMix Pro


ron45

#2
Thanks for taking the time to be so helpful. I need to check the pdf but I think there is no mini stereo out. Sometimes that requirement gets you into off the shelf home stereo grade equipment. But that output type would be a convenience in my case.

Also I want to gain more experience with circuits building this sort of item. It's quite possible that I'll run into some trouble regarding component compatibility but even then I'll be learning something.

Ron
3 Eastman Archtops, Ibanez PM100, Custom built tweed Princeton 34 watt 12" spkr Roland HPD15  2 Avalon 737sp  8buss 16 track Tascam Mixer  Lexicon PCM91 reverb deity Digital Performer Mac pro, Kurzweil K2500, GR 1 GR 30 GK3 on Eastman 910  64 fender jazz bass bought new  AKG 712  CAD VS2 tube mic

Elantric

#3
The Rolls PM-351 is a workhorse for me

I use the front 3.5mm headphone out (next to the knobs)  as a  mini stereo out



and both the "INST IN" and LINE INPUT are a stereo TRS jacks 

QuoteAlso I want to gain more experience with circuits building this sort of item. It's quite possible that I'll run into some trouble regarding component compatibility but even then I'll be learning something.

read our DIY  area
https://www.vguitarforums.com/smf/index.php?board=21.0


i always felt the GMArts POD interface was ideal project for this
http://www.gmarts.org/html/gpi.htm



ron45

#4
Thanks for that scholarly reply, I think that build is something I could try after a few simpler builds to get my fingers wet.  I probably shouldn't have used the  word `sum' regarding the signals. It implies the level of sophistication in your build. It's a bit ambitious for my present skill level.

Ron
3 Eastman Archtops, Ibanez PM100, Custom built tweed Princeton 34 watt 12" spkr Roland HPD15  2 Avalon 737sp  8buss 16 track Tascam Mixer  Lexicon PCM91 reverb deity Digital Performer Mac pro, Kurzweil K2500, GR 1 GR 30 GK3 on Eastman 910  64 fender jazz bass bought new  AKG 712  CAD VS2 tube mic


admin

#6
DIY - update your unbalanced outputs to TRS balanced with a pair of these:
SparkFun (PID 14003) THAT 1646 OutSmarts Breakout






https://www.amazon.com/gp/product/B06Y1TY9GP/ref=crt_ewc_title_dp_1?ie=UTF8&psc=1&smid=A1LHQ5G6ONPXVT

Solution to add a balanced audio output to your circuits
THAT 1646 IC
1/4" TRS (Tip Ring Sleeve) socket
Unbalanced-to-balanced output driver


The THAT 1646 OutSmarts Breakout Board offers an easy solution to adding a balanced audio output to your circuits. The THAT OutSmarts technology has been designed as a high-grade analog line driver and offers a low distortion and high common mode rejection in real-world audio applications. Each breakout board combines the THAT 1646 IC, its supporting components and a ¼" TRS (Tip Ring Sleeve) socket. With these powers combined, you will find it very easy to use the output drivers on breadboards and in projects!

The THAT 1646 OutSmarts Breakout and its sibling, the THAT 1206 InGenius Breakout, perform mirror-image signal conversion. While the InGenius is a balanced-to-unbalanced input receiver, this OutSmarts is an unbalanced-to-balanced output driver. We have made sure to break out each pin you need to utilize the OutSmarts board including the unbalanced input (IN), the positive and negative power supply rails (V+, V-) and, of course, ground (GND). Additionally, adjacent to each leg of the socket are test points for the signal (T, R, S) and normal (TN, RN, SN) contacts.