T1 Trim/Volume setting

[Geoff Stephens]

Hi Guys

Despite having used my T1 for around a year I have to admit that the trim thing still has me baffled as to it's usefulness so I'm hoping somebody could explain what it's actual purpose is.

My set up is L1 M2 with B2 and T1.

I use a KMS105 which goes into channel one with the relevant preset selected.

My guitar goes into channel two and my backing tracks in 4/5.

I am happy with the sound most of the time until I need to start pushing the system and then for some reason the mic seems to lose power when the trim goes into red, it is sort of like compression kicking in and it isn't always desirable.

Is this something to do with how the trim is set?

Am I using the trim incorrectly when I use it like a volume?

In general the trim for the mic is usually set at around 12 o'clock as is the channel volume and the master volume and I usually adjust the master either way as and when required.

I'd be grateful if somebody could explain the correct way to set it up because when a gig is in full swing I need to be able to raise the overall volume to counter the mood of the crowd.

I did a gig Saturday in a nice venue and by the second set I had around 100 people on the dance floor but the moment I started going into classics like Sweet Caroline the mic seems to cut out when the trim hits red, it's quite debilitating when you need to maintain power across the room.

I use my B2 mostly on the middle setting so am wondering whether setting it at maximum for noisier gigs might help maintain the output a bit rather than the compression effect I am getting when I drive the system.

Grateful for any tips.

Cheers guys

Geoff

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Edit Subject: Previously "Trim/Volume setting" 
Bose Pro Community Admin  

[ST - Pro]

Hi Geoff,

Please check out this video.

I'll be back with more responses to your questions a little later.

ST

[rogueacoustic]

From personal experience, thru advice I found in this forum, I now run my master volume around 2 o’clock, then adjust my individual channel volumes, after setting my trims. 
I always had these system “compression” issues when I first bought my L1S. Not anymore. 

[Fish-54]

Hi Geoff,

The video in ST's post is the best guide to using the ToneMatch mixers, but the concepts really apply to any mixer with a "trim" or "gain" control.

I've always considered the signal path analogous to a garden hose (but of course water and electricity don't mix! )  You control the amount of water going into your hose with a regulator (i.e., trim control) on the side of the house.  If your water pressure is too high, you may burst the hose.  At the other end of the hose, the spray attachment (volume control) adjusts the water leaving the hose -- the more you squeeze, the more water flows out.

In the same way, the trim controls the maximum amount of signal entering your mixer.  Too much signal causes saturation, overload, clipping, etc., that will end up being processed further down the line  That's why you adjust the trim control as in the video -- by setting each channel by playing or singing as loud as you will during performance and increasing the trim until you get flashes of red, then back off a little.  You will then keep from overloading the mixer's preamps, and have a clean signal of appropriate strength to process.  Then the mixer's settings (presets, zEQ, comp/gate, reverb, etc.) are applied and sent to the channel's volume control.  The volume controls then do the mixing -- balancing the channel signals sent to the master volume control, and from there out to your amplifier/speakers.

I'm definitely not a plumber or electrical engineer, but I think this explanation of signal flow through a mixer has served me well over the years.

I hope that helps!

[ST - Pro]

Hi Geoff,

Geoff posted:

Hi Guys

Despite having used my T1 for around a year I have to admit that the trim thing still has me baffled as to it's usefulness so I'm hoping somebody could explain what it's actual purpose is.

As you know, you can connect all kinds of things (sound sources)  to the inputs of your T1.

• Some sound sources have low-level signals
  Examples: microphones and piezo pickups (those without preamplifiers).
• Other sound sources have higher level signals
  Examples: instruments with electronics like an acoustic guitar with a preamp built-in, keyboards, other mixers

The trim control is used to take the signal from the sound source and match it to the internal circuitry in the T1. We do this matching when the sound source is at its loudest.

Set Input Trim

Turn the Trim setting up until the Trim Light is solid green with occasional flickers of yellow. Use the Trim lights as your guide. (The exact position of the Trim knob is not important).

If you see flickers of red (below), turn the Trim down. You are definitely nearing or in compression. Turn the Trim down until there are no red flickers.

Once you set the trim, you don't need to change it unless you change the sound source. That change could be a different singer, or a different microphone, or a different instrument.

It is highly unlikely you need to change the trim control from gig to gig, or during a gig. Don't use the trim control to control the volume.

Use the channel volume controls to manage the balance between the sound sources on different channels.

Use the master volume control to manage the overall volume of all the sound sources together.

My set up is L1 M2 with B2 and T1.

I use a KMS105 which goes into channel one with the relevant preset selected.

My guitar goes into channel two and my backing tracks in 4/5.

Set up the trim controls for channels 2 and 4/5 the same way as on channel 1.  Solid green, flickers of yellow. No red.

I am happy with the sound most of the time until I need to start pushing the system and then for some reason the mic seems to lose power when the trim goes into red, it is sort of like compression kicking in and it isn't always desirable.

If you haven't changed the trim setting, then maybe you are singing louder than when you set the trim initially. If you see red, turn down the trim.

Is this something to do with how the trim is set?

Am I using the trim incorrectly when I use it like a volume?

Don't use the trim as a volume control. Use the channel volume controls.

In general the trim for the mic is usually set at around 12 o'clock as is the channel volume and the master volume and I usually adjust the master either way as and when required.

I'd be grateful if somebody could explain the correct way to set it up because when a gig is in full swing I need to be able to raise the overall volume to counter the mood of the crowd.

Turn up the master volume.

I did a gig Saturday in a nice venue and by the second set I had around 100 people on the dance floor but the moment I started going into classics like Sweet Caroline the mic seems to cut out when the trim hits red, it's quite debilitating when you need to maintain power across the room.

Yes, that can happen when you clip the input (you see red on the trim light).

I use my B2 mostly on the middle setting so am wondering whether setting it at maximum for noisier gigs might help maintain the output a bit rather than the compression effect I am getting when I drive the system.

Certainly, experiment with the B2 switch. It only affects the frequencies below 200 Hz.

Grateful for any tips.

Cheers guys

Geoff

Questions?

ST

edit: Fish and I were typing at the same time. Fish was faster. I had not seen Fish's reply when I wrote this post.