Axiom Home Page Forums General Discussion Technical Questions Amount of gain on EP500 volume control

When calibrating the EP500 sub, how much gain (in dB) should I expect when moving from minimum gain to maximum gain on the volume control/knob of the amp?

I currently have my sub calibrated to 75 dB (to match the left front speaker) and the volume control/knob is at approximately 7:00 with the receiver's trim at -10 dB (left front speaker is at -3 dB). How much of an increase (in dB) should I experience if I increase the sub's amplifer gain control to its maximum setting while keeping the receiver's volume/settings consistent?

Thanks in advance!

Is your home fully paid off, and/or do you have a line of credit to cover the repairs you'll have to make?

Bryan, first a little bit of terminology/technology. The volume control on an amplifier, including a sub amplifier, isn't actually a gain control. Amplifiers provide the full designed gain of the incoming voltage whenever they're on and receiving some input. This is typically about 25-30dB of voltage gain, which is an increase in the voltage of a bit less than 30 times. What the volume control does doesn't change the amount of gain, but either allows all the incoming voltage through to be amplified(at its maximum setting)or reduces the incoming voltage to practically zero(at its minimum setting).

Now, at the minimum setting the sound level would be essentially zero, while at the maximum setting when a strong bass signal was input the sub might play at well over 100dB if the sub amplifier was capable of the required output and the sub driver could handle it(neither may be possible; just because there's room left on the volume control doesn't guarantee results). Maybe 40dB over the 75dB figure might be possible with a good sub.

I am not quite sure I understand your post. Are you saying you have your EP500 gain contol set to max while the gain on the receiver for the subwoofer is set -10?

Are you using an auto setup or an SPL meter when you calibrated?

I would set the subwoofer gain to the half point (maybe even less) and set the receiver trim to -4 to start and then gradually increase the trim on the receiver to level match the subwoofer using an SPL meter.

If using an auto setup, I would set the sub gain to half and run it mulitple times to see what kind of results you get.

No, he said he has the volume(gain) knob at 7 o'clock and the receiver at -10db level. I think most of us run our 500 and 600's knob pretty low, around 6-7 o'clock, 2however, I'm able to have my receiver closer to 0dB (-2dB) must be because of my larger room.

It is unlikely he will be able to start at the midpoint on the EP subs, historically that brings your drywall down.

Hi,

As Dr.House has pointed out, you should increase the AV receiver sub level trim towards the -2 or 0-dB mark, so that the subwoofer gets enough voltage from the AV receiver to ensure that the auto-on signal-sensing function will kick in and activate the subwoofer, especially with low-level music CDs.

You certainly never want to run the sub's own volume control at maximum. Find a kind of happy medium between the sub's volume control and the AV receiver's sub level adjustment.

Regards,
Alan

As sirquack mentioned, the EP500 volume control is at the 7:00pm setting while the Outlaw 990 receiver's subwoofer channel setting is at -10db (compared to -3dB for the front left main channel).

I am a little concerned that I've trimmed the receiver's setting to -10dB as per Alan's post - not getting enough voltage to ensure the subwoofer's amp is turned on. However, if I set the receiver's setting any higher, I'll need to turn the EP500's volume control closer to the minimum volume setting (perhaps 6:00pm to 4:00pm).

My original question was how much variance (in dB) I should expect between say 6:00pm and 12:00 on the EP500 volume control? For example, if 7:00pm on the EP500 at -10 dB on the receiver yields 75 dB (when played at reference), what should 12:00 on the EP500 yield?

Perhaps I haven't explained this well enough. I ask because I had to send back a faulty EP500 amplifier due to a faulty volume control. I'm simply wondering how much variance should exist between minimum and maximum settings on the EP500 volume control.

Thanks!

I can’t give exact number but I can offer some perspective. When I first set up my EP500 I misread the documentation and the sub volume at 9 o’clock with the receiver at 0dB and played a test tone. Before I could hit the mute button the windows, dishes in the kitchen and something inside the TV started rattling violently. To get it down to 75dB with the receiver set at 0dB I turned the subwoofer volume down to between 6:30 and 6:00 o’clock. I can’t imagine what it would have done had I set it to 12:00.

Turning it down won't hurt anything.

Bryan, the concern that you describe shouldn't be a major one. If you want the sub trim on the receiver to be significantly higher than -10(although it's possible that the 990's sub output is higher than most)so that you're confident that enough voltage is being fed in to keep the sub amp "awake", turn the volume control on the sub even lower than 7:00. There's no disadvantage to this, as it just cuts the part of the incoming voltage that actually winds up being amplified in the sub amplifier down farther.