the ever-constant overpower/underpower debate

Posted: Mon Apr 14, 2008 6:59 pm

guys guys - you are getting way too far ahead.

i simply asked if it would damage the amp or speaker.

we all know our gain structures,
we all know that it wouldnt maximize the speaker,

that wasnt the question. i knew you guys would get carried away.

so it's fine for my speaker to be rigged up. thanks for the answer.

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Posted: Mon Apr 14, 2008 7:14 pm

Quote:

we all know our gain structures,
we all know that it wouldnt maximize the speaker,

Glad you got your answer, but keep in mind that this site is viewed by people from all walks who may not know or understand proper gain structure (I work with a number of them), and who don't understand paltry mathematical equations such as Ohms Law - or what RMS stands for, for that matter.

Let's not close the door on a thread that may be of use to others lurking here!

(We have not yet begun to get carried away)
Wink

Posted: Tue Apr 15, 2008 10:17 am

Ohms law --> V=IR ??
RMS is Root Mean Square and is Peak / root(2)

Gain structure...I understand it, I just don't (want to) implement it.
If I do, and PFL something, I get blasted by the suddenly HUGE signal compared with the cut down main mix. The cabs are powerful enough to blow the hall away, the peak meter never gets beyond -20. The faders are at 0 so I don't get my ears blown out when soloing.

Would proper gain structure MASSIVELY improve the mashing together of stuff on busses? Going from about -20/25dB peak per channel to about 0 peak on a low end mixer, which will always sound lousy anyway.

Posted: Tue Apr 15, 2008 6:20 pm

Wasn't your first foray on this site about the noise induced into your system at the church?

If you're running everything that far below unity then naturally you're gonna get that nasty mess in the mains and monitors!

Set your channels at unity and gain the amps accordingly.

And lower the PFL volume pot, to avoid getting blasted in the future (your board does have a pot for the PFL, doesn't it?).

Posted: Wed Apr 16, 2008 5:19 am

"Wasn't your first foray on this site about the noise induced into your system at the church?"
Yes it was. I can't see the wood for the trees now (or can't hear the noise for the hissing).

I started setting channels properly at a rehearsal last night, recorded it as well. Just got no way of getting those recordings off the comp and into my ears until Sunday.

"Set your channels at unity and gain the amps accordingly."
Will do. Although the main amp is in the mixer and has a power setting/input switch but no sensitivity, gain etc. It just runs off the relevant faders.

The big problem is that the Main has no PFL and is by default AFL'd. With the main fader part-down I turn up the Ctrl/Phones and thus, hear it properly. *BUT*
"(your board does have a pot for the PFL, doesn't it?)"
It doesn't. The Ctrl/Phones IS the said pot. So the PFL is like 10dB or more above the normal volume.

Posted: Wed Apr 16, 2008 4:27 pm

What is that board, an old Peavey XR1200 or something?

Posted: Wed Apr 16, 2008 7:48 pm

A Phonic K-16
Discontinued, they use the K-16 plus now, which has differently marked pots (most of the "0 to 10" became "-20 to +20")

Good enough for our needs but I can think of so many times I could find a use for grouping, 2 swept mids, a PFL pot, more Auxes...
Having never had it makes it more desirable.

Edit: added link.
Oh, and the only thing I like about this better than some Mackie Onyx's I eyed up was that the Auxes are pre/post fader per channel (on Aux 2, Aux 1 is set to pre). Big selling point really.

Posted: Wed Apr 16, 2008 9:53 pm

When you PFL, you're only getting the PFL'ed signal in the phones, correct?
If so, then you wanna treat the phones level pot as a PFL/AFL level pot.

If you set your inputs at unity, and your output to the desired level on the mains (set to the proper SPL requirement in the house), I bet you'll find that both the input channels PFL'ed and the mains AFL'ed are closer in volume than they currently are...

-and as an added bonus, your noise floor will drop considerably!

-and a second added bonus - you'll be able to turn down the aux sends to the monitors, giving you more headroom and lower noise there as well.

Not setting your gain structure properly is bad, m-kay?

Posted: Thu Apr 17, 2008 5:50 am

Yes (along with any other PFLs). I will, just the initial change that's a pain.

I need to find out A) what the SPL currently is and B) what it should be.
If I set everything correctly then the actual > required.
The reason? 2 400W speakers plus monitors (even turned down) plus live band = plenty noise in our hall. I've been complained to once about it being too loud. It's an over providing system IMO. Maybe someone would call it quiet but noone complains much. What I should do is turn the amp power down from 500 to 300W and run it hotter (still peaking about 0 though).
Also, I'm sure that the biggest noise source is the input signal and the pres. Running it hotter brings up the noise floor as much as the benefit. I only gain a bit of floor back from having it set right.

Btw the hall is 70' long x 25' wide with the stage behind the front wall. Pic if you're interested.

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