DIY PMC MB2 clone

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About positioning;
You also could place both mid and high NEXT to the low units, which could than be placed closer to each other.

And;

NO bracing of the front panel? That's where the mayhem mostly starts:confused:

My approach to this is, place a brace that makes the front panel at the point of the driver as small as possible, so the panel at the location of the driver almost has the same surface (cm2) as the driver. NO panel resonance (well hardly any) as a result.

You could do;
1 - Front to back
2 - Side to side
3 - Top to bottom.

If you place "1" and "2" off center, they will fit nicely.

"3" will hit "1" or "2", take your view.

As for your drivers, the SB Acoustics W024P-8 has an efficiency of 88dB, that is NOT much, also compared to the mid and high units. Requires some clever filter.
 
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About positioning;
You also could place both mid and high NEXT to the low units, which could than be placed closer to each other.


Ooops, sorry did no see post 22:eek:

Yep so number 4 looks to me like the first go.

number 1 also looks like a candidate, but as being mentioned, turn it on its side for correct position of mid and high.

2 and 3 would be no option to my view, they both have 2 ports blasting alongside the high unit.
 
By the way, forgot to ask;

Why leave the TL option? I think that a TL (properly designed) gives a much better low end control than a bass reflex does. This adds to lower distortion, which is one of the reasons people like TL's.

It will only take some time and a bit of wood to give it a go.

I did some A - B (on paper, using design software) with a few drivers (Volt RV3134, Faital Pro 12PR300 and some others I don't recall) in a bass reflex opposed to the same driver in the same volume TL cabinet with the filter settings and the same amount of power. Result:

1 - MOST drivers in the TL showed about ½ (sometimes even more) of the excursion in the region below say 50 Hz,
2 - MOST drivers showed higher SPL in the TL below the Bass reflex tuning point (from ½ dB to 3 dB varying per driver)
3 - The TL (although could be tricky) showed 3 major "tuning" points, where you could make it honk to your liking. That is at the closed end, right at the driver position and at a small offset of the open end of the TL. A BR can also be "tuned" but that is more the character of the sound, light damping can make it a bit "harsh" while much damping will make it more smooth but at the cost of a Db or 2.

In a studio, you want to have an Honest open sound with loads of detail. The TL seems to be the better candidate, although we see loads of BR versions for a studio. HHmmm :confused:

When I find the time, I intend to post a thread on this, not really theoretical but more practical comparison.
 
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About positioning;
You also could place both mid and high NEXT to the low units, which could than be placed closer to each other.

And;

NO bracing of the front panel? That's where the mayhem mostly starts:confused:

My approach to this is, place a brace that makes the front panel at the point of the driver as small as possible, so the panel at the location of the driver almost has the same surface (cm2) as the driver. NO panel resonance (well hardly any) as a result.

You could do;
1 - Front to back
2 - Side to side
3 - Top to bottom.

If you place "1" and "2" off center, they will fit nicely.

"3" will hit "1" or "2", take your view.

I get what you mean. The design has to be altered to get the tweeter and mid vertically alligned so I will redesign the braces as well.

As for your drivers, the SB Acoustics W024P-8 has an efficiency of 88dB, that is NOT much, also compared to the mid and high units. Requires some clever filter.

Originally the Volt mid is paired with the RV3134 in the MB2 which has 91,5db sensitivity. I thought that two WO24P would compensate to a healthy 91db. But ok, the idea is to use a DCX in the beginning and to move on to a DEQX or something more high end in the future.
 
By the way, forgot to ask;

Why leave the TL option? I think that a TL (properly designed) gives a much better low end control than a bass reflex does. This adds to lower distortion, which is one of the reasons people like TL's.

It will only take some time and a bit of wood to give it a go.

I did some A - B (on paper, using design software) with a few drivers (Volt RV3134, Faital Pro 12PR300 and some others I don't recall) in a bass reflex opposed to the same driver in the same volume TL cabinet with the filter settings and the same amount of power. Result:

1 - MOST drivers in the TL showed about ½ (sometimes even more) of the excursion in the region below say 50 Hz,
2 - MOST drivers showed higher SPL in the TL below the Bass reflex tuning point (from ½ dB to 3 dB varying per driver)
3 - The TL (although could be tricky) showed 3 major "tuning" points, where you could make it honk to your liking. That is at the closed end, right at the driver position and at a small offset of the open end of the TL. A BR can also be "tuned" but that is more the character of the sound, light damping can make it a bit "harsh" while much damping will make it more smooth but at the cost of a Db or 2.

In a studio, you want to have an Honest open sound with loads of detail. The TL seems to be the better candidate, although we see loads of BR versions for a studio. HHmmm :confused:

When I find the time, I intend to post a thread on this, not really theoretical but more practical comparison.

The TL cabinet for the RV3143 was too large for our control room. The outcome of designing and building a TL cabinet is too uncertain for me. I don't have enough time to tune/experiment with it to get it right . A br cabinet is more predictable. Maybe I will do some designing/experimenting with TL enclosures on a next project.
My experience is that under 200hz every room sounds so different that correction is always needed to get optimum flat response and extension.
 
Since you are using two 8Ω woofers per side have you decided how you are going to wire them up?

In series you double the impedance to 16Ω and consequently halve the power available to them but also double the cone area resulting in no change in output.
In parallel you halve the impedance seen by the amp and so double the power and also double area resulting in a 6dB net gain over a single 8Ω woofer given the same voltage.
 
Option 1 in landscape: Somehow more... satisfying perhaps?

An externally hosted image should be here but it was not working when we last tested it.


An externally hosted image should be here but it was not working when we last tested it.


This way it will be the big brother of the ATC SCM45

444502d1422043891-namm-2015-atc-launches-scm45a-pro-high-performance-three-way-active-loudspeaker-scm45a-pro-3-4-copy.jpeg
 
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Your pictures show monitor speaker placements close to walls and desks.
A woofer in a well designed sealed box will have superior transients, plus more accurate room equalization than a ported box design.

W___Woofer on top(sealed box volume) {Satori WO24P}
T___Tweeter at ear level {Satori TW29R-4}
M___Midrange butted below tweeter(sealed box volume) {Satori MR16P-4}
Crossovers at 200Hz and 1.8kHz

Passive crossover between the tweeter and midrange.
Bi-amp the woofer with bass equalization which provides both bass boost to compensate for the modest volume sealed cabinet, plus room equalization for walls/desk.

WalterPPK, have you modeled sealed-box woofer designs?
A modern plate amp like the Dayton SPA250DSP includes DSP for the woofer, plus a crossover output to the Mid-Tweet amp.
Detals...Details...Details... The 5.5" Satori MR16P-4 is a hi-detail midrange with an underhung motor and tiny Le=0.1mHz.
You can build a cabinet where the TM baffle can be removed and rotated 180 degrees to allow classical tweeter on top TMW alignment.
 
Charles, We also have a slight preference for the landscape option.

LineSource, the room is acoustically treated. The speakers are close to the walls but there are large bass traps in the corners behind the speakers and 15cm fabric covered rockwool on all the walls and ceiling. There are no parallel walls and the desk is slanted to avoid first reflections.

Thanks for the advise but the units are already shipped. I did check the sealed option. I was thinking of making two presets in the active filter and plugging the ports and do some listening. This is the simulation with the same cabinet size and a 20hz LR high pass at x-max:

An externally hosted image should be here but it was not working when we last tested it.
 
Polar response modeling for the Volt VM752 looks OK, but the Satori MR16P has a much wider single lobe polar pattern.

-The Volt VM752 recommends a crossover of 500Hz or higher. Fs = 400Hz
-Comparison: The ATC 175 used in the SCM45A Pro has a 380Hz crossover.
-The VM752 has an 200mm = 8" in magnet diamenter.
-The Satori WO24P are 224mm in diameter.
-Comparison: The SCM45A Pro uses 164mm = 6.5" woofers

-500Hz wavelength = 688mm = 27.1"
-500Hz quarter wavelength = 172mm = 6.8"
-woofer-woofer separation in your box estimated at 350mm = 13.8" = half wavelength at 500Hz crossover
-polar response modeling shows one very narrow lobe at 500Hz.

A midrange like the Satori MR16P_4 is flat to below 200Hz in a sealed volume, and will easily meet the quarter wavelength goal.
 
The ATC also doesn't meet the 1/4 wavelength requirement. 380hz = 224mm. Woofers are 340mm apart.
How important do you regard the lobing problem?
What about option 4? This design only has the vertical comb filtering, right?

Woofers center distance is of the landscape design is 364mm (14,3")
What would be the options to reduce lobing, apart from exchanging the Volt?
- Lower the crossover point to 400 and correcting the response?
- Put a 200hz passive highpass filter on one of the woofers?
 
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