2-way Synergy Horn : Did I get the basic science/idea right?

[Giri]

I am considering to build a 2-way 900~ 20000 Hz Unity/Synergy horn.

1) One driver (D1) handling 900~ 7000 Hz and the other (D2) 7000 ~ 20000 Hz, both being compression drivers.

2) D2 will be at the origin/apex of the horn.

3) A couple of D1s will be at a distance of 0.5", on the horn wall, away from the D2. Because the cross-over frequency is 7000 Hz => wavelength of 2" and the two drivers are to be separated by a distance of one fourths of the cross-over frequency.

4) And @ bwaslo's spreadsheet is adequate to iron out rest of the details

5) I chose compression drivers because the whole reactance annulment seems a bit too complicated to understand , even for closed back drivers. And for open-back drivers, it's an order of magnitude more difficult to understand, not to mention the bother of making little chambers for their rear. If I ever find the perfect driver, that is...

Please let me know if I have got any of the Unity horn basics correct.

Thanks

 

[wonderfulaudio]

It will be tough to get so many D1s crammed into tight space.
Whats the rational behind the choice of frequencies?

For home listening, a 1.35" compression driver will easily extend to 1khz, flanked by 4 mids of 3" or 4" which can extend to 300hz. Of course, woofers will be needed outside the horn. Its hard to improve that configuration.

 

[cowanaudio]

A BMS 4550 can do 900Hz at way higher than domestic levels on a CD horn.

This will be far simpler than trying to pull off your proposed speaker.

 

[Giri]

It will be tough to get so many D1s crammed into tight space.
Whats the rational behind the choice of frequencies?

For home listening, a 1.35" compression driver will easily extend to 1khz, flanked by 4 mids of 3" or 4" which can extend to 300hz. Of course, woofers will be needed outside the horn. Its hard to improve that configuration.

1) I want a 4-way where each driver will not cover more than 2.5 to 3 octaves
2) I determined my cross-over frequencies based on the equal loudness curves. The sensitivity reduces for the lower mid between 1000 ~ 1500 Hz. Which is followed by a high sensitivity region that extends till 6000 Hz or so. I am trying to avoid crossing over i the high sensitivity region

Fundamentally, these are the two guiding principles behind the frequency selection.

Would two D1s each side be adequate?

A BMS 4550 can do 900Hz at way higher than domestic levels on a CD horn.

This will be far simpler than trying to pull off your proposed speaker.

I would think so too. Right now, it is but a thought experiment based on basic principles.

 

[AllenB]

a 4-way .... based on the equal loudness curves

Would you have made this choice regardless of whether you were putting them in an MEH or on to a baffle?

 

[chris661]

I question the wisdom of point 1 above.

I'd much rather have/listen to a system of a few high-quality drivers working over wider bandwidths, than trying to fit an unnecessarily large number of crossover frequencies into the operating range.

Crossovers are difficult, especially when they're spaced so closely. Plus, with a finite budget you have to be compromising the quality of each driver.

At domestic listening levels, a B&C DE250 will cover 900Hz upwards just fine. If you want to go an octave lower, you'll need to step up to one of those BMS coaxials, or maybe a good 3" CD if you don't mind losing >15kHz. I really don't think the difficulty of a synergy horn is required here.

Chris

 

[Giri]

Would you have made this choice regardless of whether you were putting them in an MEH or on to a baffle?

Yes. The reason is the subjective impression I got from listening to OBs and Horns over several YouTube speaker audition videos, listened over fairly decent IEMs.

The PureAudioProject Trio 15 Horn 1 sound captivated me. The airy open vocals and the snappy drums and cymbals. I seem to prefer OB low end and FLH highs. So, I started out with a mere thought experiment. If feasible, it might materialise.

I question the wisdom of point 1 above.

I'd much rather have/listen to a system of a few high-quality drivers working over wider bandwidths, than trying to fit an unnecessarily large number of crossover frequencies into the operating range.

Crossovers are difficult, especially when they're spaced so closely. Plus, with a finite budget you have to be compromising the quality of each driver.

At domestic listening levels, a B&C DE250 will cover 900Hz upwards just fine. If you want to go an octave lower, you'll need to step up to one of those BMS coaxials, or maybe a good 3" CD if you don't mind losing >15kHz. I really don't think the difficulty of a synergy horn is required here.

Chris

I very well agree with you. But, I thought active cross-overs should be easy and provide high amount of control, no?

 

[AllenB]

The question I asked you was a rhetorical one. I think all of the others on this thread, myself included have something in common in our replies.

But, I thought active cross-overs should be easy and provide high amount of control

Riiight. The rules for crossing haven't changed in forever, the filter implementation is just a tiny step at the end of the process, and I probably should let you find this out for yourself.

 

[Soldermizer]

Is YouTube audio quality that good...?

I'll admit that I have not tried YouTube to listen to "speaker listening tests" or similar. Like most of us, I use it to watch videos or listen to podcasts on topics that would get us fired from our jobs if they caught us


But seriously, is the streaming quality that good that one can make informed judgment of audio quality? Even if the original audio is recorded in PCM (or some high quality format), isn't the streaming format some kind of lossy format that is anathema to all things hi-fi?

 

[Giri]

I'll admit that I have not tried YouTube to listen to "speaker listening tests" or similar. Like most of us, I use it to watch videos or listen to podcasts on topics that would get us fired from our jobs if they caught us


But seriously, is the streaming quality that good that one can make informed judgment of audio quality? Even if the original audio is recorded in PCM (or some high quality format), isn't the streaming format some kind of lossy format that is anathema to all things hi-fi?

I agree with you. But difference between an LX521 and Avant Garde is noticeable. In spite of limitations, YouTube still allows certain level of discernment.

 

[Giri]

The question I asked you was a rhetorical one. I think all of the others on this thread, myself included have something in common in our replies.

Riiight. The rules for crossing haven't changed in forever, the filter implementation is just a tiny step at the end of the process, and I probably should let you find this out for yourself.

LOL! I did notice that trend in the replies. I concluded that my proposed Unity horn looks like a non-starter, for all practical purposes. I noted, it is a thought experiment more than anything else.

 

[Patrick Bateman]

Yes. The reason is the subjective impression I got from listening to OBs and Horns over several YouTube speaker audition videos, listened over fairly decent IEMs.

The PureAudioProject Trio 15 Horn 1 sound captivated me. The airy open vocals and the snappy drums and cymbals. I seem to prefer OB low end and FLH highs. So, I started out with a mere thought experiment. If feasible, it might materialise.



I very well agree with you. But, I thought active cross-overs should be easy and provide high amount of control, no?

You're the dude from the Facebook group, right?

On Facebook, I literally provided a parts list of how you could make the Pure Audio Project speaker for under $600. The woofers are Eminence Deltalites.

 

[Giri]

You're the dude from the Facebook group, right?

On Facebook, I literally provided a parts list of how you could make the Pure Audio Project speaker for under $600. The woofers are Eminence Deltalites.

Which group do you refer to?

 

[cowanaudio]

The woofers are Eminence Deltalites.

Don't be so sure.

DELTALITE(R) II 2515 - Loudspeakers | Eminence Speaker

 

[Giri]

Don't be so sure.

DELTALITE(R) II 2515 - Loudspeakers | Eminence Speaker

Deltalite Qts seems to be too low to be used for OB applications. Or did I miss some detail?

 

[Patrick Bateman]

Don't be so sure.

DELTALITE(R) II 2515 - Loudspeakers | Eminence Speaker

Well look at that!

 

[Patrick Bateman]

Here's the Eminence Deltalite 15, $340 a pair : https://www.parts-express.com/pedocs/specs/290-595--eminence-deltalite-2515-spec-sheet.pdf

Here's the Pure Audio Project OB 15 Neo Cast Woofer, $570 a pair : Audiophile-grade 15" Open Baffle Woofers

The latter appears to have a shorting ring that the former lacks, along with a higher Re, QMS, QES and QTS

Basically all the changes you would make to extend the high frequencies while also modifying it to work better in an open baffle