Using a 31 band Eq

EQ guys are using on their cabs/systems. A good starting place if you don't have your own RTA.
Message
Author
Rich4349
Posts: 855
Joined: Wed Jul 30, 2008 10:18 am
Location: Kankakee, IL

Re: Using a 31 band Eq

#16 Post by Rich4349 »

Yes, I've been trying. I turned off the limiter, and ran it up full tilt, only getting 18-23V, depending on how the inputs are configured. Which is the right setting: Stereo, Y, or 1+2 Summed?

I've also been trying the XTi's built in pink noise generator, with no better luck.
2 DR250s, 2 27" Lab15 T-60s, 2 30" Neo Titan 39s, 1 Autotuba...and looking for more!

Rich4349
Posts: 855
Joined: Wed Jul 30, 2008 10:18 am
Location: Kankakee, IL

Re: Using a 31 band Eq

#17 Post by Rich4349 »

I can get ch 2 to clip, but not ch 1. And for a SPLIT second, the meter may read 73v, then drop right down to like 32 or so, that's with NO limiter set. That's with ch1+2 on the input side, and both gain knobs cranked.
2 DR250s, 2 27" Lab15 T-60s, 2 30" Neo Titan 39s, 1 Autotuba...and looking for more!

User avatar
BrentEvans
Posts: 3044
Joined: Thu Oct 09, 2008 10:38 am
Location: Salisbury, NC

Re: Using a 31 band Eq

#18 Post by BrentEvans »

Use a sine wave instead of pink noise.
99% of the time, things that aren't already being done aren't being done because they don't work. The other 1% is split evenly between fools and geniuses.

Rich4349
Posts: 855
Joined: Wed Jul 30, 2008 10:18 am
Location: Kankakee, IL

finding new and unique ways to screw up

#19 Post by Rich4349 »

OHH, I'm so dumb. Or ignorant. Probably a hellacious combination of both. I had the multimeter set to AC- AMPS. I saw the "20A" and thought "Oh, that should be safe, don't want to cook the meter...again. (internal fuses) It seems you can only run a couple dozen volts though one of these for a minute or less...

And, after setting the meter to V AC, the XTi produced a whopping 79V- and clipped well as expected. So set the limiter to -3dB, and got about 57V. -6dB got 40.5. So I've decided on -3dB and 6 detents down from max, making 49.5 V. Sound about right? 5 clicks down gives 52.8; still safe but apparently yielding smaller and smaller results.

But the $64 question is: Why wouldn't the XTi clip when I was measuring current, but it will when measuring voltage?
2 DR250s, 2 27" Lab15 T-60s, 2 30" Neo Titan 39s, 1 Autotuba...and looking for more!

User avatar
BrentEvans
Posts: 3044
Joined: Thu Oct 09, 2008 10:38 am
Location: Salisbury, NC

Re: finding new and unique ways to screw up

#20 Post by BrentEvans »

Rich4349 wrote:And, after setting the meter to V AC, the XTi produced a whopping 79V- and clipped well as expected. So set the limiter to -3dB, and got about 57V. -6dB got 40.5. So I've decided on -3dB and 6 detents down from max, making 49.5 V. Sound about right? 5 clicks down gives 52.8; still safe but apparently yielding smaller and smaller results.?
This bears repeating... the knobs on the front of the amp have nothing to do with output. Those are input trims, and simply driving the signal hotter will overcome the reduction you are seeing. Set the voltage based on the limiter alone, with the input trims maxed out.
99% of the time, things that aren't already being done aren't being done because they don't work. The other 1% is split evenly between fools and geniuses.

Rich4349
Posts: 855
Joined: Wed Jul 30, 2008 10:18 am
Location: Kankakee, IL

Re: Using a 31 band Eq

#21 Post by Rich4349 »

Ok, I'm not resisting you on purpose, I'm just a :noob:

When I set the Input trims to full I get either

57V at -3dB (limiter setting) or
40.5 at -6dB

This is with my signal as hot as I can make it. Pre amp maxed, every volume maxed out. I would like to find a happy place between those two voltages. I didn't know how to boost the 40.5 setting any more, so I did the only other thing I knew: run the hotter setting and take it down from there. What is the proper way that I'm not seeing? And terms like 'unity gain' are still lost on me. Sorry.
2 DR250s, 2 27" Lab15 T-60s, 2 30" Neo Titan 39s, 1 Autotuba...and looking for more!

Gregory East
Posts: 3496
Joined: Sat May 13, 2006 9:56 pm

Re: Using a 31 band Eq

#22 Post by Gregory East »

I'm coming to the conclusion the xti original series are too rough and ready to get the absolute max out of our horns safely.

Say you set the limiter with the attenuators down some notches. You make the input clip and you get the max volts at -3db setting. Afaik that's well and good until someone comes along to help the show along with "more bass". They turn it up for you when you're not looking and 72v hits your drivers on the big thumps until they give up.

40v is nothing to sniff at but not what you bought into.

You could trade up to a new series xti2002 with the fully adjustable limiters, or get a compressor for your amp.

Unity gain is 0db reference voltage. Once you get through the yamaha book a couple of times it should all sink in. There are some very good articles in the education section links.
BAT10, Bad Auto Tuba. Reverse folded TAT to fit JBL 1014D, 350W driver, voltage limit unknown.

Rich4349
Posts: 855
Joined: Wed Jul 30, 2008 10:18 am
Location: Kankakee, IL

Re: Using a 31 band Eq

#23 Post by Rich4349 »

Well even if someone did that, it would still only feed 57 V, which is approaching the higher end, but still within the safe range. And I THINK there's a way to disable the input trim knobs functionality, too.
2 DR250s, 2 27" Lab15 T-60s, 2 30" Neo Titan 39s, 1 Autotuba...and looking for more!

User avatar
BrentEvans
Posts: 3044
Joined: Thu Oct 09, 2008 10:38 am
Location: Salisbury, NC

Re: Using a 31 band Eq

#24 Post by BrentEvans »

Rich4349 wrote:Well even if someone did that, it would still only feed 57 V, which is approaching the higher end, but still within the safe range. And I THINK there's a way to disable the input trim knobs functionality, too.
99% of the time, things that aren't already being done aren't being done because they don't work. The other 1% is split evenly between fools and geniuses.

Gregory East
Posts: 3496
Joined: Sat May 13, 2006 9:56 pm

Re: Using a 31 band Eq

#25 Post by Gregory East »

Rich4349 wrote:Well even if someone did that, it would still only feed 57 V, which is approaching the higher end, but still within the safe range. And I THINK there's a way to disable the input trim knobs functionality, too.
I don't think you have hit it hard enough with a sinewave yet. My xti2000 hit 53v at -3db. I think it was seistres who blew some 3015lf going hard out with one at -3db, yours is twice as powerful, careful as ye go.
BAT10, Bad Auto Tuba. Reverse folded TAT to fit JBL 1014D, 350W driver, voltage limit unknown.

Rich4349
Posts: 855
Joined: Wed Jul 30, 2008 10:18 am
Location: Kankakee, IL

Re: Using a 31 band Eq

#26 Post by Rich4349 »

Check out the voltage gains here: http://www.crownaudio.com/amp_htm/xti.htm#specs

XTi 1000: 30.5 dB.
XTi 2000: 32.9 dB.
XTi 4000: 34.2 dB.
XTi 6000: 37.1 dB.

Yeah, I lost where I was going with this. Maybe someone who understands this stuff'll pipe up. I don't know how much harder I can hit a sinewave, other than full volume everywhere. But then again, I've been screwing this stuff up all week- why stop now?!
2 DR250s, 2 27" Lab15 T-60s, 2 30" Neo Titan 39s, 1 Autotuba...and looking for more!

Gregory East
Posts: 3496
Joined: Sat May 13, 2006 9:56 pm

Re: Using a 31 band Eq

#27 Post by Gregory East »

I should be able to figure out what decibelised voltage is all about but I'm too foggy this morning.

Not to worry. 4000w is on tap with xti4000, needs limiting more than a xti2000!
BAT10, Bad Auto Tuba. Reverse folded TAT to fit JBL 1014D, 350W driver, voltage limit unknown.

Rich4349
Posts: 855
Joined: Wed Jul 30, 2008 10:18 am
Location: Kankakee, IL

Crown 4002

#28 Post by Rich4349 »

"When I set the Input trims to full I get either

57V at -3dB (limiter setting) or
40.5 at -6dB"

So I'm just now finding out about the Crown 4002 (or any of the x002 series) that have a fully definable limiter, with single digit dB increments, as well as fully definable knee, attack, release, etc. Would this amp be worth me looking into? I've read that the difference between 55 volts and 66 volts (the 3012LF's max) is negligible, approaching the point of diminishing returns. Aside from the 10 or so last volts to squeeze out, what benefit is there from using an (XTi?) 4002 over an XTi 4000? How much better off would I be using that $750 to build another pair of T-60s or Titan 39s?
2 DR250s, 2 27" Lab15 T-60s, 2 30" Neo Titan 39s, 1 Autotuba...and looking for more!

Bruce Weldy
Posts: 8301
Joined: Fri Nov 27, 2009 11:37 am
Location: New Braunfels, TX

Re: Crown 4002

#29 Post by Bruce Weldy »

Rich4349 wrote: How much better off would I be using that $750 to build another pair of T-60s or Titan 39s?
Or, you could buy a Driverack and use cheaper amps without dsp.

6 - T39 3012LF
4 - OT12 2512
1 - T24
1 - SLA Pro
2 - XF210


"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."

byacey
Posts: 948
Joined: Thu Jun 14, 2012 9:09 am
Location: Edmonton, Alberta, Canada

Re: Using a 31 band Eq

#30 Post by byacey »

Rich4349 wrote:Check out the voltage gains here: http://www.crownaudio.com/amp_htm/xti.htm#specs

XTi 1000: 30.5 dB.
XTi 2000: 32.9 dB.
XTi 4000: 34.2 dB.
XTi 6000: 37.1 dB.

Yeah, I lost where I was going with this. Maybe someone who understands this stuff'll pipe up. I don't know how much harder I can hit a sinewave, other than full volume everywhere. But then again, I've been screwing this stuff up all week- why stop now?!
All you have to remember is a 6db increase equates to doubling the voltage, -6db means the voltage has been cut by half. Knowing this, it's easy to count up or down by sixes to calculate voltage to db, or vice versa.
Built
T48s
WH8s
SX212

Post Reply