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radulescu_paul_mircea

Powersoft M-Force FLH or Tapped horn

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Hello everyone!

 

There was a post on Facebook Danley Sound Labs page, where a Caleb speaker was on a truck and I've asked what if he would use the M-force for bass instead of normal drivers (8*30" instead of 12*18" or something like that). Ivan Beaver answered this :

 

"The M-Force does not lend itself to horn loading-unless they make a few large changes.

 

And then it would only be good for below 30Hz or so

It is NOT just the size of the cone-but how it is used that makes the difference"

 

I have read a lot lately about all kind of speakers and subs and I understand that in a horn,the bigger is not always the better, but I am always fascinated about exaggerated things :D and I was daydreaming about a (very) large TH or FLH with two M-Force and wondering if it would work, what it's specs would be and what would 4-8 of them would do on a large outside club with an olympic size swimming pool and enough space for 4-5k people (around 6000 sq. meters).

Because on the PS Datasheet of the M-force they specify that he 22" and 30" can be used horn loaded and beacause I am just beginning to learn how to model horns (so i have very little experience to find out myself why it won't work) I am asking you to help me with more information,if you have the time to satisfy my curiosity.

 

Thanks,

Paul.

 

PS: sorry for the bad english :)

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MemX    97

Your english is fine, don't worry :)

 

 

How much are the M-Force?  If they are $$$$ then it's likely that better results could be achieved with multiples of smaller, cheaper drivers, I think?

 

 

You could always model the Stereo Integrity HS24 in a horn, although as it wants a big box even in a Sealed box, a horn would be huge!

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Yes, SI hs24 in a horn would be huge and I don't know if it can withstand a high compress ratio. In a TH the theory sais it would have a +6 dB gain over a ported enclosure. So, yes, it would be huge but also VERY loud.

But the M-Force has a much stronger diaphragm (the cone for the 40" variant is 4 mm thick) and a huge of a motor, like 25-60 (i don't really know for sure)  times more powerfull, so it could, in theory, be a very powerful midrange driver in a horn :) 0.o 

The price for the driver with amp module could be at around 4000 $ or more, but what I am trying to find out is what are its limits, what it could do, what are the benefits. If I have space and number limitation and could use maximum 2*3 DSL BC218 (this means 60" by 60" by 90" space limitation/side)  , could it be possible to build something louder that goes deeper?

It is a discussion here where the bass maniac inside me re-awaken because I've listened to a DSL BC415  and I tought "if there would be a sub with that power AND the low extension of the TH221 in a single box, It would be the clubbing utopia".

 

http://www.diyaudio.com/forums/subwoofers/268269-powersoft-m-force-specs-now-available-3.html

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Ricci    652

The M-Force is $$$$ no doubt about that. Very hard to get a hold of as well unless you buy a turn key system.

 

I don't see any reason the M-Force drivers couldn't be horn loaded but the frame sizes and depth of them plus the mounting system makes that very impractical IMO. Also the parameters are way out of the ordinary but the DSP system could be used to make the driver behave like something a bit more normal.

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Ricci    652

I'm really not that impressed with the M-force drivers personally. Of course I have not used or heard them so I may be proven badly wrong later. They are huge and their motors are ridiculous and the tech is very impressive but they are designed to get loud and not go deep. Their huge 30" has less overall displacement than the 24" driver from SI so it will likely have less very low bass output despite it's ridiculous efficiency. I do expect them to be VERY loud in the pro audio wheelhouse of 35-80Hz but we've had no trouble getting extremely loud over that bandwidth for years. I think they missed an opportunity to really push things a bit further with that motor design. I also wonder about the cone flexing on the 30 and 40" drivers. I still want a chance to play with one of these for sure though.

 

Like I said a horn for these would be extremely difficult to design due to the driver design, size and mounting scheme.

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Right on topic, Funktion One will soon release a FLH with single driver using the M-Force motor and a custom made 32" diaphragm and it will be BIG :)

In the presentation of the "novel approach" the bandpass enclosure reached around 145 dB from a single enclosure with single driver. I am curious what did F1 manage to squeeze from it. And I bet it has a very high compression rate.

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Ricci    652

Those are some huge cabs for sure. Assuming the guy is about 5'8" the cabs are about 36" high each. Depth is probably 50-60"? Hard to tell with that perspective. BIG. I'll check out the Funktion one site for more details.

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Ricci    652

Looks like it's probably a 4th order bandpass with a bit of shaping and flaring to the front vent unless there's entry from a secondary somewhere into the mouth behind that grill.

 

Interesting that there were reports of subs having thermal protection issues. Those drivers are seriously low impedance. The average is much higher than normal due to the extremely large impedance peak but near the minimums like in a vented cab it will still be very low and that has to be difficult for an amp to dump current into a 0.5 ohm load especially if the content has a repeating note near a minimum.

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I believe the problem is the lack of active cooling . In a normal driver the moving of the coil creates air currents and that exchanges the heat between the driver and the medium but here they use only convection. In the F32 from Funktion one I believe they use the driver as per the image attached with a small chamber of air and in a horn enclosure using 8 of them which behaves more like a full horn.that raises the impedance for a good bit. The thermal inertia is very high so even though it is hard to increase the temperature, it is also as hard to decrease it . The M-Drive can generate around 5000 watt long term and 2000 watts thermal equilibrium so in 2 minutes you increase the temp with 20 degrees Celsius

post-3306-0-13500200-1477746846_thumb.jpg

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So taking that much power even in a very high efficiency system the heat will accumulate very fast. Using the metal wings attached to the motor one can increase the heat transfer but it is not as efficacious as forced air. And using the TruePower counter from Powersoft K10 generating around 1.2-2 Kw per channel drawing on average 3.1 Kw from the wall, to see how quick and how high 4 BC 18PS76 per channel will heat up, in 45 minutes of bass heavy music I ended the test because I got around 35 degrees Celsius increase. So putting only that power in 8 vented drivers I could get that temperature increase. Now imagine 2 KWh in a single 22 kg motor.

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SME    210

That looks a lot like a BP6 hybrid system, but with the drivers mounted backwards (?) so that more airflow moves over the rear end to cool it.  Very impressive design.

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Yes , I like it a lot. The driver is backwards and stuck to the grill to increase cooling.I simmed it and it can get 142 dB în HR from 31 hz with only band pass filter and 3 PEQ entered.Quite easy to set it. port particle velocity at 50 m/s so not bad.at the mouth it will go to about 28 m/s and that will act as an efficient cooling method. The efficiency is very high, more than 12% from 33 hz up in singles

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Ricci    652

Yes , I like it a lot. The driver is backwards and stuck to the grill to increase cooling.I simmed it and it can get 142 dB în HR from 31 hz with only band pass filter and 3 PEQ entered.Quite easy to set it. port particle velocity at 50 m/s so not bad.at the mouth it will go to about 28 m/s and that will act as an efficient cooling method. The efficiency is very high, more than 12% from 33 hz up in singles

 

 

Want to share the HR model you cooked up?

 

Retail price on the PK? I'm going to guess $10K each.

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The input is this. post-3306-0-77132400-1483551596_thumb.jpg

Then with the added eq one will get this

post-3306-0-30269100-1483552016_thumb.jpg

Could be better go sure

Taking to account the eq and crossover the port velocity would be up to 70m/s and the front velocity would be at around 30 m/s at 25 mm excursion. It would be very chilly :)

post-3306-0-59884400-1483551649_thumb.jpg

post-3306-0-15671500-1483551667_thumb.jpg

post-3306-0-60772400-1483551687_thumb.jpg

post-3306-0-50170700-1483551711_thumb.jpg

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Looks like it's probably a 4th order bandpass with a bit of shaping and flaring to the front vent unless there's entry from a secondary somewhere into the mouth behind that grill.

 

Interesting that there were reports of subs having thermal protection issues. Those drivers are seriously low impedance. The average is much higher than normal due to the extremely large impedance peak but near the minimums like in a vented cab it will still be very low and that has to be difficult for an amp to dump current into a 0.5 ohm load especially if the content has a repeating note near a minimum.

This is how the STS M-sub looks like without grille

post-3306-0-66179300-1484406511_thumb.png

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As it turns out Ricci, the fact that the joint point of the driver is too small and the long term pressures and acceleration are to high for the diaphragm materials, they keep braking in use because the producers are not developing their own specific membrane to suit their application.

I have this information from a sure source now so this is not only a speculation anymore.

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Ricci    652

As it turns out Ricci, the fact that the joint point of the driver is too small and the long term pressures and acceleration are to high for the diaphragm materials, they keep braking in use because the producers are not developing their own specific membrane to suit their application.

I have this information from a sure source now so this is not only a speculation anymore.

 

Hmmmm. Thanks for sharing that. It's not surprising really. The attachment point is different from what you would see on a normal driver and is a relatively small area. The acceleration forces these can produce is very high. The cones are very large diameter with a ton of mass and to top it off they are being placed into high pressure, horn, BP, slot type loadings.

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