Big Main Monitors Project

[lolo-m]

Hi,
I'm new to this forum but I plan to build some big main monitors for my studio...
I would like a 3 way system, processed by a fds-366 or XTA-226 (or a cheaper Behringer maybe).
I would like a minimum "flat" response down to 30 Hz (I would like to have 20 Hz but it will be difficult)...

2 options front me :
- The cheaper is to use my Tannoy DMT-12 speakers in a closed cabinet for mid and highs and to had a sub bass cabinet based on a JBL 2241H on each side (I already own them).
- Building new monitors from scratch based on a Beyma TPL-150 (looks like what I'm looking for), surounded by 2 mid drivers (Audax PR170-0M0 would maybe fit and I already own some), completed by two 15 or 18 inches woofers on each side...

I want them to be really good and flat. I know how to correct the phase and amplitude on FOH drivers so that's not the deal. The deal is to choose the solution (closed or bass reflex) and the drivers to have a good monitoring with minimum distorsion.

Any comments ?

[sqlkev]

low distortion, high efficiency...sounds like AE speakers will do the trick

AE Speakers --- Superb Quality, Unforgettable Performance, Definitely.

[studiotech]

Sounds like fun! See here:

HTGuide Forum - Lambda TD12's + AMT monitors

and here:

http://www.gearslutz.com/board/high-...-complete.html

for more info on my main monitor project. We used the TPL and Lambda woofers.

Greg Begland - Phat Planet Recording Studios - Orlando Florida - Audiophile Quality Recording, Mixing, Mastering, Production

[Spasticteapot]

If you're feeling flush, Seas Excel W22EX001s are supposed to work really nicely with the Beyma AMT driver. Cross 'em over as low as you like to some giant subwoofers, and you're done.

[lolo-m]

Originally Posted by studiotech

Sounds like fun! See here:

HTGuide Forum - Lambda TD12's + AMT monitors

and here:

Custom main monitors complete! - Gearslutz.com

for more info on my main monitor project. We used the TPL and Lambda woofers.

Greg Begland - Phat Planet Recording Studios - Orlando Florida - Audiophile Quality Recording, Mixing, Mastering, Production

I must say I already seen your work and I admit it was really inpiring for me .
I'm wondering what is your lowest frequency with the 12 inches...

Another question is about relationship between the crossover frequency and the size of the drivers :
As a line array PA system intaller, I studied some of the speaker arrangements and the ones I love follow a simple rule : never have more than half wave length between the speaker centers at the cross-over frequency. This really improve the feeling to hear a single driver (like a coaxial). Taking care of this would allow only 6 inches speakers for the mid section if crossed at 1500 hz and 8 inches if croosed at 1k...
This is really true with line arrays, but maybe this is completely stupid with sources like WMTMW or WWMTM, but I bet I'm right. Tell me if I'm not, why I am or why I'm not, any opinion based on listening situations is welcome too ! thanks .

[Charles Darwin]

Your first option is eerily similar to what I have done!

I'm using Tannoy 3149 drivers from my LittleRedMonitors in a sealed cab crossed at 175Hz to Volt 3143s in a transmission line cab (very much like PMC XB2) and at 12kHz to some Fountek JP 3.0 ribbon tweets.
The whole lot is driven by two modified BSS FDS360s (changed the original TL072 op amps to OPA2134, removed the limiters and relays), feeding an MC2 Audio MC750 (to the Volts), an MC450 (Tannoy woofer), an MC2 T500 (Tannoy tweeter) and an Omniphonics Footprint 150 (Founteks). Due to the peculiarities of Tannoys old pepperpot tweet I also use a parametric eq to flatten its response. The 12DMT driver, having a tulip waveguide, can do without that and also without the Founteks.
The tulip tweeter reaches 22k while the pepperpot drops off at 16k.
The Tannoy driver itself is crossed at 1200Hz which gives a nice even polar pattern between the 12"woofer section and the 90deg horn tweeter.
All xover slopes are 24dB L-R.
I've measured the whole lot to be +- 2dB in room (25Hz to 20kHz) and the sound is exceptionally clean.
Tannoy listed 0.5% total distortion for the original LRMs at half rated power and while I have not the means to test distortion there is no doubt in my mind that that has been improved upon.
The boxes are constructed from 18mm MDF covered in a lead replacement membrane and then encased in 18mm baltic birch ply (front baffles are 24mm ply). The drivers are fastened to the ply only, for this I had to recess the t-nuts and trim the allen bolts to the exact length. They are pretty inert now and kinda heavy too.
I am quite happy with the result as they retain all the things I like about Tannoy DCs but with better and much more extended bass and treble.
Another good thing is that they never change the sound character even at dangerous levels of SPL, I just have to be careful with the volume!
The only drawback I can see is that they do not fit into any existing soffits.

[studiotech]

We are getting good response from the sealed enclosure down to about 65hz.

Yes, accoring to the physics, our crossover point is too high for the best intergration, but any lower and the Beyma started to sound a little strained. The crossover @ 1.8K was the best compromise...we didn't want to do a three way, so both drivers are right at the edge of their comfort zones. So far no problems. Remember, we are going for the best sound at engineers seat, and don't don't worry about the best sound over a large area like PA concert line arrays. Bob Katz has been over several times and thinks they are the best main monitors he has ever heard. As long as you are in the sweet spot!

My next project is a "spare no expense" 3 way design, either dipole or cardiod radiation, with the big Raal on top, mids to be decided as testing and listening goes on and some Lambda OB woofers on the bottom. Should be fun....

Greg

[lolo-m]

Originally Posted by Charles Darwin

Your first option is eerily similar to what I have done!

I will certainly start with a 3 way solution close to yours as I already have nearly everything to do it. I will try with the JBL 2241H drivers I own for the sub-bass section. It seam to be a quite good driver (not too much distortion) but I'm not quite sure to be satisfied with the ultra low end because of it's resonance freq which is a bit too high IMO. But it handles a lot of power so twisting it with an active controller will maybe lead me to the point I want...

[lolo-m]

Originally Posted by studiotech

We are getting good response from the sealed enclosure down to about 65hz.

Yes, accoring to the physics, our crossover point is too high for the best intergration, but any lower and the Beyma started to sound a little strained. The crossover @ 1.8K was the best compromise...we didn't want to do a three way, so both drivers are right at the edge of their comfort zones. So far no problems. Remember, we are going for the best sound at engineers seat, and don't don't worry about the best sound over a large area like PA concert line arrays. Bob Katz has been over several times and thinks they are the best main monitors he has ever heard. As long as you are in the sweet spot!

My next project is a "spare no expense" 3 way design, either dipole or cardiod radiation, with the big Raal on top, mids to be decided as testing and listening goes on and some Lambda OB woofers on the bottom. Should be fun....

Greg

Thanks for your answer. Really interresting specs and reference ! I need those speaker to be quite large in coverage terms as they'll be used as customer monitors too. I want the customers to hear something revelant in the main part of the mixing room. So like in large areas I need a good speakers coupling not to have too much accoustic dip filters... I know that the only solution to really acheive that is mono signal driven into a single full band speaker !!!

I will try to have a look to your next project too...

[Charles Darwin]

You could try those JBL 2241s in a transmission line cab as their shallow roll off and lower system resonance gives you quite a bit more usable bass extension in room but they would be VERY large indeed!