What's to chat about?

[Seth]

I don't know, perhaps it's not any sort of coincidence the max widths currently stated in the plans equate to essentially a 5 Ft² mouth area. Maybe that's a thing?

It's not. As the cab is made wider the mouth grows larger, but so does the throat. If the throat is too large you lose sensitivity at the upper end of the horn pass band. The maximum width is determined by that factor.

Would 30" wide be a poor choice in a 12" loaded T48 for that reason?

[Bill Fitzmaurice]

That's why the largest recommended width with a twelve is 24 inches.

[Seth]

10-4 Thanks Bill

[Grant Bunter]

I'm inquiring specifically about the 12" loaded cabs.

I've chosen to use the lower powered Delta 12LFA drivers and start with a foursome of cabinets. I'd like to explore what options are available to squeeze every bit of sensitivity out of them, then weigh all the options before making my final cab choice.

In the current plans, 15" is the minimum width for both, the T39 and the T48. The T39 goes up to 30"... well, 28" in the new plans. I'm just curious if the T48 could make use of that width and pick up a couple dB average too.

I don't know, perhaps it's not any sort of coincidence the max widths currently stated in the plans equate to essentially a 5 Ft² mouth area. Maybe that's a thing? Maybe there's some reason it can't/wont be able to take advantage of more? I'm not curous enough to need to know WHY it's possible or not possible to squeeze a couple more dB out.

Don't need a lengthy explanation.

Just a statement like "there's no gain to be had going wider than X".

I think you should maybe go back to your "number crunching" thread and re visit and rethink.
A 12LFA is, what, $100USish a pop?
And a lab12 or 30123lf $220ish a pop?

If you're after maximum output from any given cab, get the more premium drivers straight up.

IMHO, makes no sense at all to spend $400 on drivers, then try and get some reasonable money back when selling them, to buy premium drivers.

I went a similar way, I went 2 then another 2 BP102 loaded 20" wide T39's, because at that time it was all I could afford, in my own head only.
While I am not unhappy with those cabs at all, those 4 are not as loud (subjectively, I haven't measured) as the 2 x 28" wide 3012lf loaded cabs!
The 4 x 20"s don't keep up with 2 x DR250 either.


Do it once, do it right, build as wide as pack space allows, with premium drivers...

[Seth]

I think you should maybe go back to your "number crunching" thread and re visit and rethink.
A 12LFA is, what, $100USish a pop?
And a lab12 or 30123lf $220ish a pop?

If you're after maximum output from any given cab, get the more premium drivers straight up.

IMHO, makes no sense at all to spend $400 on drivers, then try and get some reasonable money back when selling them, to buy premium drivers.

I went a similar way, I went 2 then another 2 BP102 loaded 20" wide T39's, because at that time it was all I could afford, in my own head only.
While I am not unhappy with those cabs at all, those 4 are not as loud (subjectively, I haven't measured) as the 2 x 28" wide 3012lf loaded cabs!
The 4 x 20"s don't keep up with 2 x DR250 either.


Do it once, do it right, build as wide as pack space allows, with premium drivers...

Thanks for the thoughts Grant

At this point, I'm not trying to get the maximum output per cab. I'm wanting as much sensitivity as possible, the most output per specific voltage input. In my current plan, they wont see more than 35volts and I'll likely limit at 30, no matter what driver is in there.

I thought about going with the BP102 option in a T39. However, I did want the flexibility of upgrading the drivers if I wanted to run a more powerful system in the future. So, that's why I chose D12LFA's. Wasn't really a cost driven decision. Although, I did pick up 4 D12LFA's for about $300 USD... and not needing to spend an additional $500 to fill the cabs with premium drivers didn't bother me at all.

[Grant Bunter]

All good....

[Seth]

I'm bored. You guys got anything interesting to chat about?

[Seth]

Okaaaaaaaaay. I'll go.

I ended up getting the Dante expansion card for my mixer, a 2 channel output dongle to run to an amp, and an inexpensive "4 in /4 out" Dante box from China (hasn't come yet). I wish the China I/O box was available as an 8-in only and 8-out only configuration. That would suite my needs much better. Once the box arrives, I'll have enough Dante outputs to supply signal to Mono Mains, Aux fed Subs, and four stage monitor mixes over Dante Network Audio.

To use the Dante expansion card, I had to take out the other expansion card I had in there which records 32 tracks to SD cards. I like the easy 32 channel recording, but if I really want to record tracks I can either swap that card back in, or just use the Dante Network and a PC or outboard recorder to capture the tracks.

Anyway, in theory, the more I think about it, Dante seems like it would be awfully handy for a regular gigger (Which, I'm not... yet). I watch some of the YouTube guys (Like Stage Left Audio) and they're running 100-200' snakes from FOH to the stage, sorting out and plugging in 24-32+ inputs and however many returns at the mixing desk. That's gotta be a spendy, bulky, and heavy bit of cable to stow, transport, deploy, coil, and carry. I bought a budget brand 200 foot length of Cat5e for $14. Just snap in one RJ45 plug it's supposed to be capable of 512 channels in and 512 channels out with sub millisecond latency (as low as 250 microseconds). It coils up to about the same bulk as a 50' extension cord and weighs just a couple pounds. Crazy what can be done on Cat5e. Blows me away.

So, all that, and I've picked up some pretty cool amplifiers over the last few months. The Ashly ne8250pe is an 8 channel amplifier rated for 150w rms @ 8ohm, 250w rms @ 4ohm per channel, & 500w rms per bridged pair @ 8ohm. This model also has built in DSP... attenuaters, brick wall limiters, compressors, gates, 4 different parametric EQ's, 31 band, crossovers, delays, etc. All being configurable on the inputs or outputs. What's the difference? Any of the 8 inputs can be configured, in the software, to serve as the source for any single, multiple, or all of the 8 outputs. A DSP plugin on an input will effect any output in the configured signal chain. I can put a 31 band on an input and crossovers and parametric on the outputs. It's crazy how configurable it is and it's controlled over LAN with a PC.

I'm supposed to be able to run the Dante Audio and other non Dante LAN traffic on the same network. I'm still ironing out some details in making that work well. It seems something causes some dropout in sound when I put everything on the same network. For the moment, I've gotten around that by keeping the Dante network separate from other networked devices. I've also used a small network bridge to essentially turn the amplifier into a wireless WiFi enabled device. Makes connecting to and controlling that a breeze.

I've been going through possible speaker/PA configurations for years. I've decided to have a little fun and start small. I had a thought, what if... hear me out here... what if I could get very respectable FOH sound and stage monitors for a 4 piece band powered by one amplifier? Too fun. I love the challenge. I'm gonna do it.

Here's what I'm thinking;
4 independent stage monitor channels to four Wedgehorn 6's
1 channel Stage Right Mains, two stack DR200 parallel
1 channel Stage Left Mains, two stack DR200 parallel
1 channel Subs, parallel two 30" T39, Delta 12LFA
1 channel Subs, parallel two 30" T39, Delta 12LFA

8 channels, one amp, 2RU... no outboard signal processors.

Should be a real testament to the value of Bills high efficiency speaker designs.

[Grant Bunter]

I can put a 31 band on an input and crossovers and parametric on the outputs.

That all looks good on paper, and I'm sure you're going to make it work IRL.

Just one thing;
Do all your EQ on the input side, pre crossover.
Why?
Phase response is frequency dependant, so, unless you have access to FFT devices (I don't think they're out for PC yet), EQ alters phase, and the one thing, the only thing, you can check each time you set up, very simply, is that phase response is correct at the crossover frequency.
Add a parametric in post crossover, and start chasing your tail, as that will alter phase at the crossover point...

[Seth]

...Do all your EQ on the input side, pre crossover.
Why?
Phase response is frequency dependant, so, unless you have access to FFT devices (I don't think they're out for PC yet), EQ alters phase, and the one thing, the only thing, you can check each time you set up, very simply, is that phase response is correct at the crossover frequency.
Add a parametric in post crossover, and start chasing your tail, as that will alter phase at the crossover point...

That's really interesting stuff Grant. I've heard whispers of such things, but I was either not ready to listen or the whisper-er wasn't saying it in a way the piqued my interest. Is the phase issue something that you've experienced before? Or, are you just sharing your book knowledge? I'll do some searching on the subject, but if you've got a favorite information source in the matter, I'd be thrilled to review any links you provide too. After I read up on it, I think I'll try to create and experience it firsthand.

Incidentally, I've always put my crossovers post EQ in any system I've done and I really couldn't tell you why. I never really thought about it before, just what I've done since I was a teen futzing around with stuff in the garage. Maybe it was because the EQ was in the dash and the crossover was in the trunk? Could have just been something I picked up in magazine articles. I have no idea.

Here's a screen shot of the GUI for the DSP. Each of the blocks is a spot to insert a DSP plug-in. Plenty of plug-in insert spaces on either side, input or output, to dial everything in.

[Grant Bunter]

I don't have any links per se, search around, wade your way through a few different opinions, sort it out to your own satisfaction in a way that works for you
As time has marched on, phase is something I've come to understand a little better, and it's either largely ignored, or misunderstood.

Here's a number of statements to ponder;
Phase response is dictated by the enclosure ("It's the cab, not the driver, that dictates response").
Different cab types shouldn't be used in the same band pass (Each cab will have different phase characteristics, leading to frequency nulls).
Phase is altered by both EQ and delay.

So, what is it we do with live PA in every new room, even outdoors?
We EQ it, maybe alter delay to the backline, or tops/mains to subs.
That alters phase, so, again, the only place you can easily check after that is done is at the crossover point (Play a tone at the crossover frequency, flip the polarity button in DSP, whichever is loudest wins).

Here's the next part of the conundrum.
Altering gain alters the acoustic crossover point (as distinct from the electronic or numeric point).
So if you've added +6dB to your subs, and you think the crossover point is still the 90Hz you set it at, well, sorry, but you're wrong...

[Seth]

I'm aware of most of that. It's the part about EQ changing the phase and it's relationship to a crossover and whether it's before or after one and other in the signal chain that has me interested in the point you've made. Are you able to speak to that a little more? I read up on it a little. First couple hits on ONE phrasing of a google search anyway. And what I gathered is it's a couple blowhards trolling each other about the obsurd and amazing effect EQ has on phase and that it's how an EQ works. Most of the discussions were in the recording and DAW rhelm. I didn't find too much (yet) about the effect on PA.

In PA applications, if the phase is a little out, so what? Right? If it's a lot out flip the polarity and/or adjust delay.

No? Am I missing something?

Add a parametric in post crossover, and start chasing your tail, as that will alter phase at the crossover point

Is this statement perhaps a tad on the alarmist side, as statements go? Everything alters phase. Is it an academic point of conversation or a real issue you've encountered? How would someone be induced into tail chasing in this application? What occurs that can't be easily remedied?





This was a good watch. Although, not about live PA or phase discrepancies at crossover points

[Bruce Weldy]

I can't argue with anything Grant has said......but, in my PA world there just isn't time to worry about phase issues. The big boys get into an area 12 hours before showtime and have their high-powered Lake processors to properly time-align and EQ their systems.

Typically, I get to set everything up, run my go-to song through the PA and EQ it by ear. I do this EVERY time I'm running sound - whether on my rig or someone else's.

While it's commendable to learn all you can about these issues, I think there are other considerations that will give you a better chance of putting on a great show when time is of the essence.

1. Tune your PA - that should be done before you ever get to a show. Take it outside, use your auto-EQ if you have one in your speaker processor and then listen. Make your crossover adjustments and your gain structure between the tops and the subs and lock it in.

2. Tune the room. If you have the time and the venue will put up with all the noise it takes to use Auto EQ, then get after it. It's been years since I've been able to do this - but, even if you do - you must still use your ears to clean it up. The best use for Auto EQ is to find the low-mid crap that muddies up the mix anytime you are inside.

2a. If you can't use Auto-EQ, have your test tunes ready. Don't just pick your favorite song - find something that allows you to hear the bottom end, some kick drum, and a nice open vocal. Stay away from most of the newer heavily compressed stuff.....it's just a wall of noise and is worthless for finding problems. Pick some old Steely Dan. I use a tune called Texas by Chris Rhea. Within 30 seconds I get a low droning bass tone, then the kick, then vocals. It has a bit of a hyped top end, but I know that, so I don't get too crazy trying to filter it out.

3. Once the system is tuned to the room - your work on the individual channels becomes much easier and you'll find you need a lot less EQ......because now you are EQing just the instrument and not having to EQ the room too.....

3a. Use a high pass on EVERY channel to keep the bottom end clean. Just because an Electric Guitar goes down to 80hz, that doesn't mean that it shouldn't be high-passed up as high as 150hz if that's where it needs to be in order to not get in the way of other instruments.

If you can't tune the EQ in the room and the EQ on the channels correctly - it doesn't matter whether you have the most perfectly time-aligned, phase-correct PA in the world. You still have to have ears and know how to mix.

So bottom line in all of this is - learn everything you can about the science of sound, but once you get to the gig, focus on the things your ears can hear and make those things as perfect as possible in the allotted time and constraints of the venue. Nobody gives a rat's patootie if you got the phase right if it sounds like crap.

Of course, items 1 and 2 pertain to every system - and 3 is for the live-sound guys......

My motto is still what's in my signature line below.....

[Seth]

...

So bottom line in all of this is - learn everything you can about the science of sound, but once you get to the gig, focus on the things your ears can hear and make those things as perfect as possible in the allotted time and constraints of the venue.

It seems there's no end to the learning curve in my two favorite hobbies... sound and engines. Every new thing learned highlights two or more things that I don't yet know. Hated this in my 20's and 30's. Now, I've learned to expect it and count on it.

The routine you've outlined is very close to my current formula too. I have presets for all my cabs, EQ'd flat outdoors. Sometimes I'm able to auto EQ, other times it's not an option and I just do it manually with pink noise. If it's not appropriate to have pink noise on for extended times, I find it's helpful to snap a pic of the curve on my phone, shut off the test tone, make adjustments... wash, rinse, repeat.

I've always EQ'd flat. Is that what you guys do? I've heard other people (usually recorded content) talk about shooting for a curve about 10dB hotter in the lows. Anything to that?

Nobody gives a rat's patootie if you got the phase right if it sounds like crap.

Likewise, nobody gives a hoot about the phase if it sounds fantastic too. That's kind of my point to Grant. If it's causing a dip at crossover freq, fix it. But, what makes it an unfixable situation if an EQ is placed post crossover? That I don't get. But, I'll play around with it anyway and see if I can create the situation he's talking about.




BTW, Corona's about to poke his head in and tell us auto EQ is useless indoors. And, I'd agree that it's less than perfect, but not that it's entirely useless.

[Bruce Weldy]

I've always EQ'd flat. Is that what you guys do? I've heard other people (usually recorded content) talk about shooting for a curve about 10dB hotter in the lows. Anything to that?

I have never EQed a system flat - it just doesn't sound natural and that's not how any of us listen to music. If would require a lot of additional channel EQ to get the bottom end going where we want. That said, an overall 10db boost by just turning up the gain on the subs below the crossover point isn't anything I'd do either.

I use the curve on the driverack that has a bump on the bottom, a dip in the low mids and then it eases down as the frequency increase on the top ene. It's called "band" curve on one of the driverack models...

Ultimately though, I want a recorded track to sound good with the system EQ and I've never found that to be flat.

BTW, Corona's about to poke his head in and tell us auto EQ is useless indoors. And, I'd agree that it's less than perfect, but not that it's entirely useless.

I would disagree that it's useless indoors, as I've used it successfully to find the build up in the low mids in that 100-250hz range that adds mud. Sometimes those frequencies are harder to pick out by ear and Auto-EQ can get you there quicker. But, I typically just do it by ear because I know it's gonna' be there and so I jump right on it. I'd agree that the top end is more easily fixed by ear.

But, I wouldn't want to have someone trying to do something by ear that they haven't learned how do yet when they could let the processor do it for them. Once you see it a few times, it certainly gets easier to hear as you get more experienced.

I use my ears 99% of the time because I don't really have much choice. But, I'm grateful to have the tools available and to have used them in the past to help train my ear.

Sound can get too ego-driven.....I have decent ears, but no by no means are they better than a reference mic. By the same token - sometimes the reference mic and the software end up giving you a ridiculous EQ curve that has to be smoothed out. Use the tools when you can - not just to fix a problem, but as a learning opportunity.

Any time I mix on a big system provided by someone else, I always tell the lead engineer to offer any suggestions that they may have. I tell them that I'm there to put on the best show I can and there is no ego involved. Then during or after sound check, I'll specifically ask them if they hear anything that they would change.