Midbass horn

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Dear all,

So, I've been slowly putting together my first compression driver-based sound system:

* 2x Bill Fitzmaurice T18 subs (~25Hz-200Hz)
* 2x Pyle PDS521 2" mid/tweeter compression drivers (supposedly 500Hz-20kHz, although the horn I have for them at the moment is 1kHz)

I'm therefore missing that all-important 200Hz-1kHz range. I was thinking of using:

1 3/8 X 18 Thread 40W Rms Midrange Driver Threaded | 54-050 (54050) | Distributed By MCM

But would they work?

I'm not afraid to try my hand at making custom horns for either of the compression drivers, but I understand that distortion can become blaringly obvious if the drivers are pushed too low in their range.

I've also only really seen reviews on that driver for talkbox use, so I also question whether it is useful for hi-fi/HT/studio monitoring.

My uncertainty leads me back to the forum, to see what the gurus have to say! :)

Any advice would be greatly appreciated on this, so I offer my thanks in advance!

Dan
 
We are discussing horns on another thread..

Hope you have lots of room to spare, they can get rather large. This one is the SATO horn, built by a gentleman from Japan, hence the name. His low end cutoff is 280 Hz. 200 hz will be another factor larger.


________________________________________________________Rick........
 

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unaHm,

I see you're still struggling with driver choice.

I am not sure a $24 driver will get you where you want.
No meaurements, no reliable driver data, no brand name...

Think you need a cone mid driver.

Pyle looks better altough don't be surprised if there will
be lack of upper treble.

And for the last please count me out of the guru crowd. ;)

Wish you luck!
 
Rick and Lojzek - thanks for your information!

I think I'm insane enough to try a SATO using cardboard :)

I agree, the drivers I have are definitely lower budget ones, but I didn't want to initially spend much on my first compression driver-based horn experiment. I suppose what I could do with what I have is create a proof of concept, and then (when I can afford it), replace the drivers with more suitable ones.

The forward-firing horn idea with a cone (or compression) driver also looks like a good one that I'd be interested in trying out. The rooms I have aren't that large, but big enough to stuff these designs into the corners!

If there are any drivers that are available (either brand new or on eBay/craigslist) that might be suitable, please let me know! I'll look too, but I don't have much experience with which parameters to look for.

Thanks again!

Dan
 
If ya want to use a woofer, there are some b&c 12" drivers with Fs around 54hz and qts .18, that'll horn load to 500hz anyway (pretty high for a 12) and maybe sag a bit at 1khz.

I've been thinking of these as a double 12, but as a big midbass horn approaching 100hz with around 5ft2 mouth on the floor, and crossing at 750hz.

Norman
 
Interesting stuff. Thanks for the additional viewpoints!

I like both ideas in terms of using a 'high bass' compression driver, or a 10/12" speaker in a horn. I think because the compression driver approach is so new to me, I'd be tempted to take that route (for now).

I've heard a couple of demos of the Goto horn (https://www.youtube.com/watch?v=sUKqUr8sIUc for example), but I can only imagine that the drivers are hideously expensive, rare, or both!

Am I correct in that assumption?

I'll also keep searching on the Radian and B&C drivers.

I also suppose that given their price it might be worth trying out those no-name brand drivers...you never know, they may end up being like the 69 cent woofers! ;-)
https://www.youtube.com/watch?v=sUKqUr8sIUc
 
I've been looking at the JBL "ex" Pro audio compression drivers on the web, and there are lots of them...unfortunately way beyond my budget at the moment!

I've also found a spec sheet for those compression drivers mentioned earlier:

http://www.mcmelectronics.com/content/ProductData/Spec%20Sheets/54-050.pdf

Correct me if I'm wrong, but the scale of the frequency response graph only shows a 50db range! Er, wow! If that IS the case, why would they bother?!

My other thought was to look for some old PA speakers (or enclosures that may have been used in cinemas) that may be damaged, but still contain useful drivers (i.e. "people don't know what they're selling"). Any recommendations on what I should look for?
 
Thanks for the responses...I've been researching them, and bookmarking them for the time I can afford those :)

I received a parts express catalogue today, and noticed this:

Dayton Audio D1075T 75W Driver with 70V Transformer | 300-190

Upon first thought it didn't seem that it would be feasible given that the stated nominal input was specified as 70.7v. However, the transformer itself can be bypassed, so given that it has a frequency range of 180-6000Hz and a SPL of 110db, it certainly seems to be a contender!
 
Ok - which again takes this driver out of the running, as we lose the range that we need.

Thinking about mid(bass) horns that use cone drivers, why are the speakers used in all of the designs (that I've found) 15"? It seems quite large for that application!

However, from some more reading I've caught a tiny bit of information that suggests that the driver size is needed to be used in conjunction with a small(ish) throat to provide proper loading. Am I along the right lines?
 
Hi unaHm,

I too am thinking about an all horn loudspeaker around a cheap phenolic midrange driver. Since these type of drivers seem to be the only way to close the +- 500 - 5.000 Hz range on a budget.

50 - 500 Hz 8 or 10 inch, in a folded frontloaded horn Klipsch / Vitavox Thunderbolt style.
500 - 4.500 Hz Selenium D250X on a big biridial ABS horn 18" w x 10" h x 12 " deep.
4.500 Hz -> "Denovo DNA 150" type neodymium driver on a small biradial horn. Eminence EM 200 ish.

About the 50- 500 Hz midrange horn. Maybe someone with more experience can help us out?

If you use a 12 or 10 inch driver instead of a 8 inch driver and shorten the horn. Let's say from 1.7 meter (8 inch driver) to 1.5 meter. Compression ratio, mass roll off all beeing the same does this improve the upper midrange part? Would this sound better in real life? Whereby i mean, does someone have experience with this shortening besides simulating it in hornresponse.

I understand folding a bass midrange horn is "not done". Would the midrange performance in a folded horn increase a lot with a stronger magnet? Let's say mass roll of 700 Hz instead of 400 Hz.

Would it help to split up the bass midrange horn in 2 or 4 path's. Multicel horn way?

Anymore suggestion's for improving midrange performance in a folded midbas "Klipsch / Thunderbolt type" horn. Besides smooth transitions, big roundovers, felt or foam around the mouth?

Regards Anonymus,
 
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After many trials I find the simplest and good way to split up a hornloudspeaker operating range is in decades or close to decades. A cone driven horn up to 250-300. Then cone, compression drivers are OK but forget about a cheap girly one other than some big Atlas or ideally 4" phenolic (the little Selenium 250 barely gets to 600 cycles) a 5, 6 or 8" in straight horn 250-300 up to 1800-3000. I have one where a 2" throat is used with a 6.5" that does 250 to 2,5K very well, stomps JBL 2482 & Altec 290 - The BC 6PEV13 in 180 flare round wooden tractrix. Then use your favorite 1" compression driver for treble. You can go further but these frequency ranges are fairly easy to get right.
 
same that's an impressive graph for the little (18"x18"x19") T18 posted at BFM's site - better in ways than my Klipschorns. A 6" or 8" cone on a 150Hz tractrix might blend ok. University's Cobraflex although small mouth, had a long path. I would use a small Karlson topped with K-tube (or loaded with fullrange or coax).

my lone 1970's Klipschorn in an 18x27 foot room K33 CTS - orange trace with 2.5mH inductor - aqua = no inductor
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EV 1823M ~30uF highpass - three different horns outdoors and on-axis
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Adrian Mack conical horn with Alpha6A and Edgar 250Hz tractrix with JBL alnico LE5 - outdoors and on-axis
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same horns on and 30 degrees off horizontal axis outdoors
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Dr. Bruce Edgar's 100Hz hypex horn outdoors and on-axis JBL2220 vs Klipsch K43. (the distortion is for the K43 - 2220 ran probably 10dB higher IIRC)
This horn has a 20"x20" mouth and about a 20" path from mouth to an 80 sq. inch throat. Total depth with back chamber was around 28 inches.
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10 inch driver Karlson coupler
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Thanks POOH,

I will look into a bigger phenolic driver for 500 Hz and up. By the big Atlas you mean the Atlas AS100N? AtlasSound.com

I found some bigger phenolic drivers, but everytime the voice coil / power handling gets bigger the mass roll off seems to limit the extention quite a bit. Like this Sammi SU 150 EF.
I believe most of the phenolic drivers originate from Voicetek China or Ahuja India.

Probably need a big, big neodymium magnet to get more extension above 2.000 Hz out of a 66 mm or larger voicecoil phenolic driver.

Anybody some input about folding a midbass and the influence of mass roll off on soundquality?
 
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