In-line fixed attenuators

Mike-48 · « **on:** 3 Mar 2021, 08:46 pm »

I hope this will be an easy question for the technical people here.

I would like to set up my system with the subs' volume controls a little higher -- now they are at 8:00, and at that area are too sensitive to changes. In my audio closet, I found a pair of "ProCo Max10 150 ohm -10 dB" inline (XLR) attenuators. That might be a good amount of attenuation to let me to set the volume pots higher and get the same volume from the subs.

BUT I have no idea whether a 150 ohm attenuator would be right for this, nor even what the impedance means in this case (I know what a 150 ohm resistor is). The specs of my preamp (Anthem STR) do not show output impedance, nor do the specs of the sub (JL Audio F112) show input impedance, if that matters.

So . . . try them? or don't?

opnly bafld · « **Reply #1 on:** 4 Mar 2021, 02:41 am »

The preamp's manual shows a subwoofer level control, have you adjusted that?

Mike-48 · « **Reply #2 on:** 4 Mar 2021, 05:49 am »

Quote from: opnly bafld on 4 Mar 2021, 02:41 am

The preamp's manual shows a subwoofer level control, have you adjusted that?

If you mean the Anthem STR Preamp, it's not quite that simple. Sub levels are adjustable, yes.

But to run ARC (Anthem Room Correction), the SPL level of the sub must be close to the SPL level of the main speakers, within a certain range, without setting levels in the preamp. (ARC overwrites them.) I can do that now, but the pot is a little touchy at that low level. Hence the thought of using an attenuator, for convenience.
I have been thinking it over, though, and maybe that's just adding more connections and more s/n killers to the system for a very minor reason.

RDavidson · « **Reply #3 on:** 4 Mar 2021, 04:26 pm »

I would think that you can still make subwoofer level changes, in your preamp, even after ARC does its thing. Seems odd not to be able to fine tune to your preference after ARC. I would exhaust that option before adding anything externally, like you said. You have to be careful with those external attenuators too sometimes, primarily the location of them. I believe putting them on the output of your preamp is where they can be a problem. At the input of your subs should be OK...but definitely double check all that before going that route.

WGH · « **Reply #4 on:** 4 Mar 2021, 05:49 pm »

After running ARC you can adjust the subwoofer level using the Room Gain setting, page 29 in the pdf manual download:

ROOM GAIN
If you wish to experiment by flattening room gain, you can try it by setting this to 0 dB. Note that auto-detected room gain will
be at or near 0 dB if bass absorbers are used or if the speakers are light on bass extension.
Alternatively if you would like to increase or decrease bass, this is the best place to do so if using a subwoofer since a good
sub-mains transition will be maintained

Mike-48 · « **Reply #5 on:** 5 Mar 2021, 01:05 am »

I appreciate the help; unfortunately, I wasn't clear about what I was trying to do -- simply set the fixed level of the subs on a different part of the pot, a part that is less fiddly.

I didn't want to change the sub gain at all. Just cut it back inline so I could boost it at the subs to get the pot to another spot. I was trying to ask if those attenuators are suitable for that.

I am aware I can boost or cut the sub level after running ARC. In fact, I often run the subs 0.5 to 1.0 dB hot -- sounds better to me.

But please, dear readers, don't trouble yourselves any further. I really appreciate your offering help. Nonetheless, I have abandoned my idea as unnecessary and the issue as something I can work around.