Diy Monitors - to build or not to build PART II

[Moby]

[quote author="Gerald Jansen"]Moby, You're absolutely right. That excel spreadsheets is about volume displacement and can be used to predict the max SPL of the drivers when selecting a x-over frequency.

Please understand that I think you're working on a marvelous speakersystem and I think you'll be very pleased with the end result. It's not my intention to get you nervous. Please keep us posted.[/quote]

Gerald, no way you making me nervous! And anybody here :thumb: I learned long time ago that "our forum" is place of kind and friendly guys and we are trying to help each other unselfishly.
So, I found your and other guys comments welcome ad will be happy if you keep posting too. Just keep coming all warnings, please :wink: :thumb:

 

[Moby]

Just you to see that I'm not just theorizing, here's the pictures from crafting start. I started fro MTM boxes....

All parts are here.... :wink:

And three of four frames are here....4th is dryn'

 

[mhelin]

Nice looking plans. Good thing that you'll build separate enclosures for both midwoofers. Beware vertical lobing though. As you have the woofers in separate boxes then if you use an active crossover you could actually control the lobing if needed (by adding a short delay to either woofer, propably to the lower one if you want to head the lobe downwards). As your tweeter's FS is as low as 500 Hz you could also use quite a low crossover frequency (I think ~1500 Hz is OK with them) to minimize the vertical lobing effect.

Considering the internal bracing I had used just a single sheet of the same stuff as the box but with (2 or 4) large holes in it (and I'd put it in the box right when the frame was glued together, it may be difficult later).

 

[Moby]

[quote author="mhelin"]Nice looking plans. Good thing that you'll build separate enclosures for both midwoofers. Beware vertical lobing though. As you have the woofers in separate boxes then if you use an active crossover you could actually control the lobing if needed (by adding a short delay to either woofer, propably to the lower one if you want to head the lobe downwards). As your tweeter's FS is as low as 500 Hz you could also use quite a low crossover frequency (I think ~1500 Hz is OK with them) to minimize the vertical lobing effect.

Considering the internal bracing I had used just a single sheet of the same stuff as the box but with (2 or 4) large holes in it (and I'd put it in the box right when the frame was glued together, it may be difficult later).[/quote]

Thanks. About MTM lobing that seems to be one of the unbeatable problems. Only solution is to go with 2.5 setup, but that can cause other problems. In my situation mid-woofers are wired in parallel, so separate crossover delay is impossible. It's maybe possible to do some passive compensation for one of the woofers. Don't know how I can do that and if somebody knows, please let me know. I imagine that like some simple low-pass filter( to skip vertical lobing in high mid), but afraid that I will ruin the similar impedance of drivers... :?
BTW, I planned the 2k2 crossing freq. with tweeter and that is not so "low". If I go lower I'm afraid that tweeter can easily drop in some ringing problem :roll:

About braces, I will make them as skeleton and I'm almost finished with that.
I tried to be precise so hope that won't be problem to push them inside box and glue. (front plate and removable back goes after)

Expect some new braces pics soon :green:

 

[mhelin]

What if you used TMM configuration instead of the planned MTM? A 2.5 way system is kind of useless because you don't need any baffle step compensation in soffit mounted system. Alternatively you could just switch off the other woofer (in MTM version) when you don't need all power.

 

[Moby]

[quote author="mhelin"]What if you used TMM configuration instead of the planned MTM? A 2.5 way system is kind of useless because you don't need any baffle step compensation in soffit mounted system. Alternatively you could just switch off the other woofer (in MTM version) when you don't need all power.[/quote]
I agree about 2.5.
Main problem in mine situation with MMT will be the height. If I put the tweeter at the top I will end very high with position. BTW It's not just mine problem. Every studio with large console will have almost the same problem. Down "M' will be under the desk. Other possibility is to put speaker higher and make some angle, but then you ruin the soffit main advantage... Here's the edge diffraction. :wink:
This MMt configuration is interesting in home or mastering situation and without soffit.
At last, yes I was thinking about that possibility... There is no "perfect" system Just best close possible.
Hmmm, I'm still thinking and if you have some more idea or maybe you disagree, just tell me. I still have some time to change my mind :wink:

 

[Sammas]

Looking good so far Moby :thumb:

 

[woodensoul]

You might look at the BSS London BLU32, it will process 96k if you can get audio via CobraNet to it. Costs $3000 here in the US. The company I work for are dealers in U.S. , but you could probably get one over there easier. You might look at Lake processors too.

- Steve

 

[mhelin]

[quote author="Moby"] Other possibility is to put speaker higher and make some angle, but then you ruin the soffit main advantage... Here's the edge diffraction. [/quote]

How about making some angle to the wall where you (soffit) mount the speaker? Anyway, the MTM configuration is fine anyway, the lobing also helps to reduce reflections.

 

[Moby]

[quote author="woodensoul"]You might look at the BSS London BLU32, it will process 96k if you can get audio via CobraNet to it. Costs $3000 here in the US. The company I work for are dealers in U.S. , but you could probably get one over there easier. You might look at Lake processors too.

- Steve[/quote]
Thanks Steve. Yes, I'm familiar with Cobra Net and BLU32. But, I was looking for some more affordable unit. Something around 1000EU (1200$).
BTW, do you have any experience with Xilica DSP's?

 

[Moby]

[quote author="mhelin"][quote author="Moby"] Other possibility is to put speaker higher and make some angle, but then you ruin the soffit main advantage... Here's the edge diffraction. [/quote]

How about making some angle to the wall where you (soffit) mount the speaker? Anyway, the MTM configuration is fine anyway, the lobing also helps to reduce reflections.[/quote]
Sorry, my wall is built already and I have to "put" this project inside.
:wink:

 

[Moby]

OK, as I promised here's the foto - progress :green:

This braces take a lot of time, but hope that will help about "sound" :roll:

Here's my assistant Mark markin' :wink:

Drilling, drilling.... :evil:

Rounding the edges. So many edges :twisted:

And, here's the one complete of braces for one box

And for all 4 :wink:

Will be back....

 

[Moby]

And some more pic's :roll:

There was important to make groups of braces and trim them nicely to drop tight in the box.
Gluing and trimming (not so hard job :green: )

Adding "small" braces

Here's the detail of "my MTM skeleton"

And at last, SKELETON BRACE :grin:

All of them are fitting nice and tight. I will not glue them until I try them with the drivers.
All drivers parts are still "traveling" from Belgium... :?

 

[Viitalahde]

Nice work, gives me the speaker building itch! :thumb:

 

[Moby]

[quote author="Viitalahde"]Nice work, gives me the speaker building itch! :thumb:[/quote]
Thanks mate :guinness:
I found this crafting as relax from recording job :thumb:
BTW, I received the drivers today. Expect new pic's soon :wink:

 

[ChrioN]

Moby: Looks great! :thumb: :thumb: :thumb:

 

[Moby]

[quote author="ChrioN"]Moby: Looks great! :thumb: :thumb: :thumb:[/quote]
Thanks :grin:

 

[ioaudio]

thats really nice work! you are crazy :thumb:

 

[Moby]

[quote author="ioaudio"]thats really nice work! you are crazy :thumb:[/quote]
Aha, and madness about woofers is still on hold. Wait to see that :twisted:

 

[Moby]

After a lot of thinking I decided to buy Behringer DCX2496 Ultra-Drive Pro. To be honest, price is so low that can't be any mistake about. :wink:
BTW I presume that some modifications is possible...
So, will be really helpful if someone can point me to the link about. When i did some google-ing I found a lot audiofool stories so my brain hurts. Will be nice to talk with someone who is experienced with this Behringer "things". :green: