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Combining compression drivers in one horn?
Combining compression drivers in one horn?
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Old 24th August 2021, 05:38 PM   #1
unaHm is offline unaHm  United States
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Default Combining compression drivers in one horn?

It's been a while, but I've started to get back into thinking about loudspeakers (though I cringe at some of the past conversations I've been involved in here!). I recently stumbled upon a low-midrange compression driver (the Miyako DU-100), and thought about combining it with the Pyle Pro PDS521 I already have.

I have 2 of each, so I could potentially make a stereo pair of...something.

How could I best combine these two compression drivers? I was thinking of aiming for a point-source design, maybe just one horn with a throat combiner, but I'd rather ask than go down too many rabbit holes!
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Old 24th August 2021, 08:12 PM   #2
GM is offline GM  United States
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Way back when I did ~the latter in a huge WG in that I made the throat as two smaller WGs to load down to 1 kHz. No measurements, just some really good female ears to guide me for the HF with open cell foam to damp reflections back to the CD throats and similar for the WG terminus back to the dual WG terminus.
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Old 24th August 2021, 09:19 PM   #3
unaHm is offline unaHm  United States
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Interesting! I think I have a visual idea of what you'd created in my head - it must have been massive! How complicated a build was it?

The only sane thought I've had apart from the throat combiner was to have the PDS521 run as the HF, and the DU-100 run as the low-mid as a side-tap in the Synergy fashion.

The PDS521 can cross as low as 500Hz (not necessary), and the DU-100 appears to be good from 110Hz - 6kHz, so there's plenty of crossover frequency options.

I'll run the end solution with subs, which I think can crossover at 200Hz.
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Old 25th August 2021, 09:48 PM   #4
weltersys is offline weltersys  United States
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Quote:
Originally Posted by unaHm View Post
1)The only sane thought I've had apart from the throat combiner was to have the PDS521 run as the HF, and the DU-100 run as the low-mid as a side-tap in the Synergy fashion.
2)The PDS521 can cross as low as 500Hz (not necessary), and the DU-100 appears to be good from 110Hz - 6kHz, so there's plenty of crossover frequency options.
unaHm,

I like the idea of "using what you got", but you really don't have good low-mid potential with what you have.

1)"Synergy" style horns are conical expansion, they provide little low frequency response unless very narrow, (like under 15 degrees) and even then 500 Hz would be pushing the drivers into "quacksville".
If you were to use a more "normal" angle, like 90x40, don't expect much below 1000 Hz from either driver.
Using the PDS521 at the apex with cone mids could do the trick down to 100-200 Hz, but a compression driver like the DU-100 won't.
2) At 200Hz using around a meter long exponential horn the low end of the DU-100 would perhaps be 90dB 1 watt one meter, and would require padding the rest of the range down to that level.

A description of what the intended use and your build complexity comfort level would be helpful to suggest alternatives.

Art
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Old 25th August 2021, 10:29 PM   #5
Mark Tillotson is offline Mark Tillotson
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Quote:
Originally Posted by unaHm View Post
How could I best combine these two compression drivers? I was thinking of aiming for a point-source design, maybe just one horn with a throat combiner, but I'd rather ask than go down too many rabbit holes!

For some reason I'm reminded of Hitler's 3rd vengeance weapon, a gun with multiple charges feeding into one very long barrel, precisely timed... And no, it didn't work very well. I fear you may have a slightly analogous problem, but an interesting one. Perhaps a less crazy comparison is with the two lungs feeding the trachea, or perhaps more accurately with the avian syrinx, birds have vocal organs before the airways merge...
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Old 26th August 2021, 01:21 AM   #6
unaHm is offline unaHm  United States
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Originally Posted by weltersys View Post
unaHm,

I like the idea of "using what you got", but you really don't have good low-mid potential with what you have.

1)"Synergy" style horns are conical expansion, they provide little low frequency response unless very narrow, (like under 15 degrees) and even then 500 Hz would be pushing the drivers into "quacksville".
If you were to use a more "normal" angle, like 90x40, don't expect much below 1000 Hz from either driver.
Using the PDS521 at the apex with cone mids could do the trick down to 100-200 Hz, but a compression driver like the DU-100 won't.
2) At 200Hz using around a meter long exponential horn the low end of the DU-100 would perhaps be 90dB 1 watt one meter, and would require padding the rest of the range down to that level.

A description of what the intended use and your build complexity comfort level would be helpful to suggest alternatives.

Art
Thanks for the thoughts Art! Your insight is always valuable, and definitely prompts my need to take a step back and look at what question I'm trying to ask.

For some reason until now, it hadn't really twigged that the low/mid taps in a synergy horn weren't being loaded by the horn...even though it's mentioned a number of times by a number of people (including yourself and bwaslo), so it now makes all the sense in the world why a low-mid compression driver wouldn't work in a similar application.

I like the idea of option 2 that you've mentioned...using a 200Hz horn with that compression driver. I'll be using these devices indoors, so I'm not looking to blast the paint off the walls (of my, er, unfinished basement...maybe deter a few spiders?). I can't say that I've attempted to make a multi-way horn system before. Some of the solutions on this forum are beautiful and fantastic, but I fear that I would get lost in time delay calculations, or just run out of room.

Would it be feasible to stack Smith horns for both drivers? I saw that bwaslo mentioned a number of years ago a passing interest in experimenting with making a Smith horn a synergy, but I have to read up more on how they work.

As for build complexity, I'm not sure - I think I'd like to spend time building a really cool physical enclosure or horn and improving those skills, and then work with a DSP.

Quote:
Originally Posted by Mark Tillotson View Post
For some reason I'm reminded of Hitler's 3rd vengeance weapon, a gun with multiple charges feeding into one very long barrel, precisely timed... And no, it didn't work very well. I fear you may have a slightly analogous problem, but an interesting one. Perhaps a less crazy comparison is with the two lungs feeding the trachea, or perhaps more accurately with the avian syrinx, birds have vocal organs before the airways merge...
Well, that first analogy I'd rather not see pan out I think this question stems from seeing those Y adapters that allow you to screw two compression drivers into one throat, but I would imagine that the intended application for those is for two of the same driver, and not differing ones.

Last edited by unaHm; 26th August 2021 at 01:26 AM.
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Old 26th August 2021, 04:39 AM   #7
Pano is offline Pano  United States
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Combining compression drivers in one horn?
The stacked Smith horns seems clever and not a difficult build. I just don't know much about that DU-100. Art seems to.
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Old 26th August 2021, 01:36 PM   #8
weltersys is offline weltersys  United States
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Quote:
Originally Posted by unaHm View Post
I like the idea of option 2 that you've mentioned...using a 200Hz horn with that compression driver.

Would it be feasible to stack Smith horns for both drivers?
Regarding the "meter long exponential horn", see the response (and directivity!) of the TOA horn/drivers below.
The TH-650 mouth is a half meter wide, it's folded (re-entrant, reflex) horn length is about 3x394mm, 1.182 meters, about 46 inches. It's sensitivity 1w/1m is about 91 dB at 200 Hz. Note the 1.275 meter TH-660 does only 1 dB more down at 200 Hz.
I couldn't find any meaningful specifications for the DU-100, at best, it might equal that of the TU-631 driver, but could be much (like -3 to -12dB) less.
A (cheap) 6" speaker in a little box would sound far better down that low, and would be around 95dB 1w/1m...

Smith (DSH) horns would work OK, but 500 Hz would be about the bottom for them.

Art
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Last edited by weltersys; 26th August 2021 at 01:40 PM.
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Old 26th August 2021, 03:08 PM   #9
unaHm is offline unaHm  United States
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Agreed - I couldn't find anything meaningful anywhere about them either - even on their website they don't provide a datasheet.

They also appear to make re-entrant horns, so it looks like they're for a specific purpose.

I'll play around with them a bit and see how quacky they get

I also have (which might be more interesting) a pair of Yamaha JA-6681B compression drivers, but wanted to be careful with them because I've been told replacement diaphragms can't be found for these any more
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Old 27th August 2021, 05:08 AM   #10
weltersys is offline weltersys  United States
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Man, don't bother with those junk drivers when you have the real deal sitting around!
The Smith horn was designed for the type of throat the JA-6681B has, similar to the old JBL, Altec, TAD, etc.

That said, I have a pair of thread on to bolt on adapters you could buy if you want to experiment with the cheapos and change over later without modifying the horn.

Art
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