2xT45's & 2xOT12's - And your time starts... Now

[AKC1]

Hi

A little coverage of my build.. Comments, wisdom & constructive criticism welcome!

Brief:
Create sound system for house parties and occasional garden parties.
Playback material will be a combination of background music and loud electronic dance music.
It has to be a geeked out system so I can actually use some knowledge gained from hanging around on sound websites and forums all the time.
Small enough to get in an estate car.
Be relatively easy to build for a first time woodworker.
Sound frickin awesome!!

Choices:
2x 24" LAB12 T45's - Got a great deal on the LAB12's, response looked good, good size with the bonus of being able to stand on a 24"x24" footprint. Can fit two in an estate car.
2x Beta12s 1.2KHz CD OT12's - Easy to build, compact, can get geeky with digital crossovers, Bi-Amping etc. Good match for T45's.
Biamp Nexia SP Digital Speaker Management - Cheap, lots of very techy features, good sound quality.
Ecler NZA4-400 - 4x400W Channel amp with integrated speaker management, cheap from work. Will run the subs and the Beta12s.
Audiolab 8000a - 2x60W HiFi amp run as power amp only(Disconnected pre-amp), great sound and sitting doing nothing but not wanting to sell. Will run the two CD Horns.

Current State:
Cutlist created
Parts purchased
Tools begged, borrowed or purchased
Wood Purchased - Managed to balls that one up with the wrong type of ply but should be salvageable... viewtopic.php?f=1&t=24835
First cuts and Jigs/Sledge

More coming soon with pics and diagrams.

Alex

[AKC1]

Must be ready for a big scheduled party in early Aug!

[Tom Smit]

Have fun!

[AKC1]

Trusty cutlist created, thanks to - http://delphiforfun.org/programs/cutlist.htm

*Part dimensions covered to protect IP

I had the timber yard cut all 6 4'x8' panels to a manageable 4'x4' so 12 panels total. Time to get busy with marking up for cutting!

Late night caffeine fuelled marking up in my pyjamas, ahh reminds me of being a Uni student... Should Probably use some sort of table before that hunch becomes permanent!

More to come...

[Chris_Allen]

I would stick your builds in their own threads.

I always start drawing in the front room too, though, I haven't tried in pajamas......

[Bruce Weldy]

I always start drawing in the front room too, though, I haven't tried in pajamas......

Can't imagine having to work in the house......or living through the beating I'd get from the missus.

[Chris_Allen]

Aha! You need to start after she has gone to bed, hence the pajamas....

[AKC1]

Aha! You need to start after she has gone to bed, hence the pajamas....

Never a truer word was spoken

[AKC1]

It has been a lovely weekend here in London and I have managed to make a good dent in all the cutting!

I have to say cutting 48" wide panels on a 50" wide balcony is a little snug..

This evening I have been setting up my loudspeaker management for how I want to use the system. The setup below adds EQ and delay on the right for EQing and time aligning the individual drive units in the OT12's. There is a delay section to match the tops to the subs and the 7 band PEQ's on the left are used to tune the system to the room. Last of note is that I have set up the pink noise to have its own output as well as running through the signal chain. This will allow me to feed the noise back into my laptop and use it as a reference signal to do system tuning with SysTune Pro. Brick wall limiters will be set for driver protection on the NZA4-400.

Alex

[AKC1]

I would stick your builds in their own threads.

If you think that would be best. I will split them when ready to start assembly as at the mo bits are being prepped together.

Alex

[Bruce Weldy]

I have to say cutting 48" wide panels on a 50" wide balcony is a little snug..

Man, I've got to say kudos to you guys building cabs without a a workshop and lots of tools.

[Grant Bunter]

This evening I have been setting up my loudspeaker management for how I want to use the system. The setup below adds EQ and delay on the right for EQing and time aligning the individual drive units in the OT12's. There is a delay section to match the tops to the subs and the 7 band PEQ's on the left are used to tune the system to the room. Last of note is that I have set up the pink noise to have its own output as well as running through the signal chain. This will allow me to feed the noise back into my laptop and use it as a reference signal to do system tuning with SysTune Pro. Brick wall limiters will be set for driver protection on the NZA4-400.

Speaker Management Config.jpg


Alex

AFAIK, using EQ post crossover alters phase. So I guess you need to ignore the EQ capability on the right for the individual component drivers.
Or, if you alter EQ post crossover, go back and check phase at the crossover point(s).
Setting delay is also going to alter phase, and since delay is also post crossover, again check phase at the crossover point after altering delay.
Checking your system phase at the crossover point is absolutely essential.

You may have to mess with it a bit, but setting your EQ on the left (pre crossover) will eliminate most of the "issues" as I described above, other than if you add delay...

[AKC1]

AFAIK, using EQ post crossover alters phase. So I guess you need to ignore the EQ capability on the right for the individual component drivers.
Or, if you alter EQ post crossover, go back and check phase at the crossover point(s).
Setting delay is also going to alter phase, and since delay is also post crossover, again check phase at the crossover point after altering delay.
Checking your system phase at the crossover point is absolutely essential.

You may have to mess with it a bit, but setting your EQ on the left (pre crossover) will eliminate most of the "issues" as I described above, other than if you add delay...

Hi Grant,

My thinking was i would start by EQing(outside open space)the individual OT12 drivers then set their delay/phase to each other(using SysTune), EQ the sub in the same way with ground plane measurements. Once those were set lock them so they dont change when visiting different venues. Then when i arrive at each venue I setup the speakers and using SysTune I align the tops to the subs(delay/phase) then use the room EQs to tune the whole system to the room/venue.

I am by no means an expert and this knowledge has come from learning on the internet so may well be floored, having explained it do you think it will work as intended?

Thank you for your help!

Alex

[David Raehn]

Don't let 'better' be the enemy of 'good'.

Hook them up and run them.

After you get over the initial shock, proceed to tune to your heart's content.

Don't let critical tuning get in the way at first.

You'll probably want to damn the lot of us for letting you get into this....

You're welcome.

[Grant Bunter]

Hi Grant,

My thinking was i would start by EQing(outside open space)the individual OT12 drivers then set their delay/phase to each other(using SysTune), EQ the sub in the same way with ground plane measurements. Once those were set lock them so they dont change when visiting different venues. Then when i arrive at each venue I setup the speakers and using SysTune I align the tops to the subs(delay/phase) then use the room EQs to tune the whole system to the room/venue.

My thoughts:
Phase is frequency dependent. Therefore, the only delay you can add is at a crossover point (subs to tops), so you can then check phase response (unless you want to go to FIR filtering).
Subs and tops need to be in phase at the crossover point. Mids and HF need to be in phase at their crossover point.
Personally I think it's almost redundant to setup delay for drivers in tops (ie between mid and HF) because there will be about 1 maybe 2msec in that setting and we simply can't tell that small a difference when applied. By all means play with it though.

I would be more inclined to save a 7 band PEQ (left on your flow chart) for subs and tops as a system save, and tweak it at each venue.
This is what I do, but with GEQ.

Mirror imaging an SPL chart is a great way to get a start point for EQ...