Topic: Question about TRS

[SClassical]

Does anyone know why they used TS plugs for a balance cable rather than TRS plugs? I thought balance cables uses TRS connection.

http://www.soundprofessionals.com/cgi-bin/gold/item/SP-MICROTRACK-MINI-TRS

[Church-Audio]

Does anyone know why they used TS plugs for a balance cable rather than TRS plugs? I thought balance cables uses TRS connection.

http://www.soundprofessionals.com/cgi-bin/gold/item/SP-MICROTRACK-MINI-TRS

When your connecting unbalanced gear to a balanced input its always good to short out the - in this case the ring against ground this will unbalance the input and allows the input stage of the MT to work correctly. This rule also applies when connecting unbalanced inputs into a balanced xlr input you always short out pin 3 to pin 1 to unbalanced the input.. Provided we are talking about a mic input for a balanced line input XLR it could be in 3 hot pin 2 cold. That's when it gets confusing so SP has made this adaptor the correct way. As it is impossible to have a stereo balanced signal on a 3.5 mm stereo jack... because you would need 5 contact points not 3. I hope that made sense..

[SClassical]

What you just said sounds complicated  Can someone explain why this site suggest we should not use the TS, then?

http://www.transom.org/tools/recording_interviewing/200512.maudio_microtrack.html

So you are saying we should use TS instead of TRS?

[ShawnF]

The device from SP is converting a signal from a stereo miniplug, which is already unbalanced.  There's no need for TRS at that point, and is better handled with two TS connectors, as pointed out above.  If, though, the signal you're wanting to record is balanced, you're better off using the TRS as indicated in the article.  And, of course, if you want to use phantom power, you must have TRS.  I don't think the article had in mind the situation the SP product is meant to allow, so I don't think the warning against using TS applies for using this adaptor.  The signal will always be unbalanced if you're starting with an 1/8" source.

[Church-Audio]

What you just said sounds complicated  Can someone explain why this site suggest we should not use the TS, then?

http://www.transom.org/tools/recording_interviewing/200512.maudio_microtrack.html

So you are saying we should use TS instead of TRS?

Ok here is the deal with balanced connections weather they are ring tip sleeve or XLR this is the rule for the connection

For balanced audio connections you have to have

1- A GROUND..
2- A signal MINUS
3- A signal PLUS

For Mono unbalanced you need to have two things

A signal connection
A ground connection

So if your using the microtracker with a unbalanced source

You should short out the ring and the sleeve together this will UNBALANCE the input of the microtracker... Since the ring in this case is SIGNAL NEGITIVE it goes to ground...

So if you use a MONO 1/4 inch jack the sleeve now shorts out the ring on the connector and unbalances the input of the Microtracker...

This is as simple as I can make it

Example number 2

Lets say you have a cd player and for some stupid reason you must connect the output of the cd player RCA UNBALANCED. to the XLR mic level input of your MIXER.... Since we know A mic input is wired like this Pin1 = ground, Pin2= Signal + Pin3= Signal - we know what pins need to be shorted in order to unbalance the input connection.

You would want to make sure that pin 1 and pin 3 were shorted together pin 2 would go to the tip of the RCA connector and the sleeve would go to pins 1/3 This would unbalance the mic input of the mixer

The only other issue with connecting a line level source to a mic input is ATTENUATION... because the mic input expects to see a signal of say -40 to -50 db or there abouts. It does not expect to see a signal of say -10 or so from the CD player so you can use a in line pad to bring down the input level..

The other issue is one of impedance because the mic input is 150 to 600 ohms you might need to run a in line impedance converter like the one sold by Hosa this converts the 10k impedance of the CD player into a low impedance output..

This is  very complicated subject and one that is a huge part of what a real sound engineer should know about connecting equipment there are many good sources for this information AES or Audio engineering Society has papers on this subject there is also a cheap book called the Yamaha sound reinforcement handbook $30 this will help you understand the theory behind what I am talking about.. A very good source for information is M-AUDIO!!! its surprises me why more people don't simply call the people that make the product for information on connecting external devices..

I hope this helps its very complicated and it took me a few years to get a handle on the do's and donts of connecting gear but once you learn you can then do more with your gear and understand the signal path in a whole new way.. Another really good source for knowledge is company's like soundcraft.. or midas they sell professional consoles for recording studios and live sound.. They also have great FAQ sections about connecting gear..

Chris Church