C/E/X PA Flat to 30 (FT30) PA TH Awesomeness

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djk

djk

R.I.P
Joined 2001
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weltersys

weltersys

Member
Joined 2008
jwmbro said:
Does that mean a 109dB/2.83V/8Ω compression driver is 50% efficient? Will hornloading the compression driver increase the sensitivity and efficiency even further? Sorry for going off topic.
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A rating of 109dB/2.83V/8Ω is probably measured on a horn of some type. Horns limit the dispersion to a smaller radiated area, raising the on axis sensitivity.

As a woofer array size increases it becomes a virtual 1/4 space radiation instead of half space.

Arrays of woofers that are large compared to the wavelength create directivity, increasing on axis level while reducing off axis level.
The efficiency remains the same, but where the sound goes has changed.
 
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Djim

Member
Joined 2009
Pasi said:
No idea who designed HGW-10.

What comes to "copying DJK's design" that is always open for discussion. Yes, since he came up with that design long long time ago it can of course be considered as copying. But let's see what you guys can come up with same criterias what i was given and how different result you will end up with, just for fun.

1. Width needs to bee exactly 700mm to allow stacking and flying with Ersa Major array which was allready designed before starting sub design.

2. 2x 18" Reflex sub in push-pull configuration.
and
3. When ground stacking, 2 subs need to give right height (Ersa Major horns above average listening plane) for tops without anything extra added to stack. With or without groundstacking frame. Stack cannot be higher than 2350 mm with 2 subs and 2 tops.

Best regards,
Pasi
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Sorry Pasi, it wasn’t meant as a personal accusation. I do understand your designing limits that made the outcome very similar. But my remark was meant cynical towards Ohm as a company. The fact is when a commercial company, like Ohm, releases a loudspeaker which shows many similarities to what have been discussed and shared over internet for years (with explanations, diagrams and pictures) it is asking for at least some cynicism:p. And I appreciate your willingness to open your cards...
 
djk

djk

R.I.P
Joined 2001
"From what many others say and love about THs, they bloom @ war volume. How are PPSL at war volume? "

Interesting that you ask.

The actual driver seen in my photos is the Eminence 15711, a custom design. The Martin #1844 is a driver that is available and fits my design quite well, even though the box wasn't designed for it.

With the 15711 the box is actually mis-tuned at lower volume levels, the Qts is a bit too low. What I found when you want to 'jam' an alignment you can pretend the Qts is a bit higher than it really is (because the motor is more powerful than what you need), but no more than about 15%~20%. When you start to pound it then the BL starts to drop off, the Qts goes up, and the cabinet comes into alignment. I guess you could call that 'blooming', it picks up more bass. The PP loading also seems to clean up a lot of the muddy sounds you get from a more conventional layout that is overdriven. PPSL sounds much cleaner all the way up to clipping.
 
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Pasi

Member
Joined 2011
Djim said:
Sorry Pasi, it wasn’t meant as a personal accusation. I do understand your designing limits that made the outcome very similar. But my remark was meant cynical towards Ohm as a company. The fact is when a commercial company, like Ohm, releases a loudspeaker which shows many similarities to what have been discussed and shared over internet for years (with explanations, diagrams and pictures) it is asking for at least some cynicism:p. And I appreciate your willingness to open your cards...
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No worries and no reason for apologies. I understand your point of view and i'm also interested to know how that 10" sub ended up to our product range as i wasn't working with Ohm back then. At the moment it looks like it came from one of our customer but i'll keep you posted when i find out more.

In my opinion in general, it is bit dangerous to start saying that someone copied some other especially at these days as most new cabinets are just bit different versions from decade old designs and principles. There is limited amount of ways of doing for example 2x18" direct radiating sub. Or for example Danley Sound Labs and Renkus-Heinz using same idea of common horn. Danley knows it as Synergy horn and Renkus-Heinz as Co-Entrant horn. Same idea, bit different approaches. Most of these "modern" inventions have been discovered before 1970s anyway.

I found this out with these PUKK subs as i tought that i'm creating bit different and original looking box, but then got cold shower which pulled me back to earth when i found out that DJK has used this same idea more than 20 years ago. But was he the first...? I've now found out that quite many companies use this same design in their subs.
 
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Djim

Member
Joined 2009
Pasi said:
In my opinion in general, it is bit dangerous to start saying that someone copied some other especially at these days as most new cabinets are just bit different versions from decade old designs and principles. There is limited amount of ways of doing for example 2x18" direct radiating sub. Or for example Danley Sound Labs and Renkus-Heinz using same idea of common horn. Danley knows it as Synergy horn and Renkus-Heinz as Co-Entrant horn. Same idea, bit different approaches. Most of these "modern" inventions have been discovered before 1970s anyway.
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I know, I do have some books/magazines (50ties/60ties) with ‘old’ designs that now and then see daylight again. About the origin of PP I have no clue. To me it was EV Voice MTS-1 for PA and in Hifi it was (don’t fall of your chair) Jamo. They released some PP’s during the eighties in their “PP” series (how original).



Crescendo, about war volume... use PP's in a TH concept and control their Xmax with old MFB techniques from Philips and you have everything you want: Low, loud, less THD and fully auto control of their mechanical limits...
 
djk

djk

R.I.P
Joined 2001
"To me it was EV Voice MTS-1 for PA "

Which they built after I talked with Tom Gallagher of Electro-Voice at a trade show. My original thought was to make something like the MTS-1, but with a horn-loaded 10 or 12. I decided that as a one-box system it was too heavy to hoist up in the air for good coverage. The MTS-1 tried to crossover at 800hz to a compression driver, I don't think that was the best thing to do. It was kind of funny that Tom was sending people over to talk to me at that show when they wanted plans to build MTL subwoofers.

The first PP system I saw was the 70s vintage Audio Pro design (see previous photo link), but it was co-planar and less than optimum in my opinion. The 80s vintage KEF 104.2 with its coupled cavity (BP4) design was PP, but also less than optimum in my opinion.

http://www.froerup.dk/jan/stereo/diverse/kef_104_2..jpg
 
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C

CRESCENDO

Member
Joined 2009
djk said:
Note:

The power you enter into BassBox v6.0 does not take into consideration the boost applied by the filter, but the excursion plot does. This means that you do not have a problem with x-max unless the program shows more than 1.5x what the driver is rated at, and that the amplifier must be able to provide 6dB (on peaks) above what you enter in the program...

...If you buy as a dealer, Martinsoundpro.com will sell you this driver for less than $100.
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So, though the drivers cost less than $200 for one PPSL enclosure, one must have an amp capable of supplying 1800W? If this is so, is a PPSL not far from a direct rad (vented) with less distortion? Seeing as it still requires huge power?

Also, what is the step-down tuning + EQ you speak of in another forum?
 
jwmbro

jwmbro

Member
Joined 2007
epa said:
here you go
couldnt scan one track,il try that later.
imo go with 30 hz since 32 hz is the lowest (repeaded) sound u want to reproduce.
you can get that with 2 per side at the cost of some spl
dubstep%20lows.jpg
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Hi, interesting analysis. What program did you use to analyze this? Do you have to pic out the time at which to analyse the song yourself, or does it search for peaks automatically? I have a few songs for which I'd be curious how deep they go also.
 
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epa

Member
Joined 2010
yup cool edit 2and update 2.1(you have to fidle a bit with the settings (fft) to get the low response )
in this case it was to see if it was necessary to model the box down to 30 hz.
you move the cursor over the loaded song ,and you'll see the graf move .
 
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epa

Member
Joined 2010
justin
ive been moddeling about every driver i could find.
i really need to know ,wat your goals are.(30 hz@ 140 db:D i know)
i mean
how much money are you willing to spend on your subs,
how much amp power is availeble.
how big is the total pakkage your willing or able to move.
with this info i have something to go on.
no free lunch indeed:mad:
 
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CRESCENDO

Member
Joined 2009
Hi epa,

Happy to hear you're still at it. I know I'm a little tough to please/picky.

I'd like to spend less than $300 per driver
I will be buying an amp sufficient for the designed cabs
I'd like to be able to hit 140dB flat to 30Hz w/4 cabs that are 15 cu. ft./ea. or smaller (best case scenario is to fit all 4 into a short bed pick-up truck w/camper shell - may be far from possible, I know).

For the meantime, I was considering the Furysub build, as I already have those drivers in my Titan 48 enclosures and they supposedly are more efficient in the Furysub. I'm just unsure about the proper confirmed plans, suggested high pass frequency and whether it's xmax limited or power limited.
 
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epa

Member
Joined 2010
have you seen this site?
email them to see for howmuch you can get 4x bms 850 v2
i dont see how you can get close with any other driver.
better spend a litle more,then go al the effort and go hmmmz:sigh:
remember xco1 600 ltr cab got to 140 @30 hz with 4.

CRESCENDO said:
Hi epa,

all 4 into a short bed pick-up truck w/camper shell -
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why not us a trailer behind your truck,
thats how i move my 4 650 ltr horns.
 
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epa

Member
Joined 2010
hi oliver
yes that one wil,but its more ~expensive vs the bms.(don't really know bms prices in us)
justin has max $300 to spend per speaker.
you wont't get 140 db @ 30 hz with 4 unless you have ~600 ltr cabs and unless u use an 18 "with a x-max 13mm or more.

you can get there with 6 or 8 cheaper speakers.
fi 8*300 ltr cabs with b&c18ps76 wil give 138 db down to 30.
4 *$350,-??? =$1400,-bms 18n850 v2
8 *$200,- =$1600,-b&c18ps76
4 *$440,- =$1760,-b&c 18 sw 115
:smash:
 
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