Questions & Answers

TRS input has preamp gain, while the manual says not.

+1 vote
1,116 views
asked Sep 3, 2017 in StudioLive Series III by yveshaeghen (890 points)
Hello,

all my line level devices are connected to my SL32 using TRS jacks for 2 reasons:

- no possibility to turn on phantom power by accident (+48V only on XLR connectors)

- no extra gain stage as per manual (page 10, preamp bypassed): simpler, cleaner.

However, I recently noticed that the preamp gain does work for TRS inputs. I'm not saying this is bad, but:

- is this normal?

- is the preamp byapssed when setting it to +0 dB?

4 Answers

+3 votes
answered Sep 3, 2017 by Gembo2011 (1,260 points)
selected Sep 4, 2017 by yveshaeghen
 
Best answer
If you go to the StudioLive Series III  Downloads area there is a Block Diagram available for all three SL Series III Mixers (32-24-16 channel).

According to the SL32 Block Diagram, using the TRS input does bypass the Mic Pre along with the 48 volts. However you are provided with a Digital Gain (Trim) of up to 20db.

On my console when I connect a XLR to channel (17 - 32), the input screen indicates 0db - 60db PreAmp Gain. This indicates I am using the Mic Pre.

When I connect a TRS to the channel (17 - 32), the input screen indicates 0db - 20db Digital Gain. This indicates I am bypassing the Mic Pre.

This is just as the Block Diagram indicates,

Hope this answers your question...
0 votes
answered Sep 3, 2017 by einsii (560 points)
Digital trim maybe?
0 votes
answered Sep 4, 2017 by yveshaeghen (890 points)
Hello,

thanks  for the quick and correct answer: I do indeed have 0 - 20 db of gain on a TRS jack input channel, you are right. It is , however, labeled as 'preamp gain' in the board fat-channel scribble strip, hence the confusion. May I also suggest to add this to the appropriate manual page (page 10), not all of us go through the Block Diagram to find such answer (though I think these diagrams are a welcome and nice addition to the manual).

Cheers.
0 votes
answered Dec 8, 2023 by ScottKozicki (160 points)

Based upon Gembo2011 's answer, following this logic, then if I bring a TRS input to the board, it will automatically bypass the pre, but if I bring an XLR to the board, it will allow me to utilize the pre, correct? Is this determination made by the signal strength on the pin (-10db, +4db, etc) or by the presence of physical signals on the pins?

...