Compression drivers?

[Flaesh]

I thought it was SEOS24, measured by @mtg90 (maybe not)

 

[robh36062]

The 877MG/877BE driver looks exactly like the Radian 951 motor. That's a fantastic motor but the exit angle is unorthodox which imo has contributed to DIYers sometimes getting disappointing results with it.

Hello Duke

Can you elaborate a bit? The original JBL 476's used the coherent wave phase plug the made them "throatless" drivers. Does the Radian use the older conical triangle cross section like a 375?

Thanks Rob

 

[Sal1950]

The key is finding the right partner. My partner and I are working together to design an ADU to house our surround system and theater.

That sounds great !
Have you approached her yet about getting a job, or second job, to help pay for the ADU ?
Just a thought.

 

[Mr. Widget]

That sounds great !
Have you approached her yet about getting a job, or second job, to help pay for the ADU ?
Just a thought.

That's a real 1950's statement... how do you know if she isn't the chief bread winner?

 

[Flaesh]

 

[Sal1950]

That's a real 1950's statement...

Just kidding you know, sorry but I'm not very 21st century PC. LOL

how do you know if she isn't the chief bread winner?

I don't, but sounds great to me.

 

[Mr. Widget]

Just kidding you know, sorry but I'm not very 21st century PC. LOL


I don't, but sounds great to me.

Yes, I won the relationship lottery.

 

[Plcamp]

This seems very good to me…almost 70 degrees at 10 kHz. I am contemplating printing an es 450 horn to use with 15” woofers.

Am I missing something? (Note the waterfall and distortion are both really good using an SB 65cdnt compression driver with a 1.4” to 2” extension to match this horn).

I consider myself dangerously semi educated about horns, so am hoping you folks can guide me if I am off track.

 

[gnarly]

It depends on the size, but in general OS waveguides are not particularly good at extending down low. Generalizing a bit, a 15" OSWG is good to about 1 kHz; 18" to about 800 Hz; and 21" to about 650 Hz.

Thank you Duke.
Without a deep understanding of the oblate-spheroid math and resultant contours, I've always kind of guessed the mouth becomes disproportionally large as xover frequency lowers. I think the info you've given supports that idea. Is that how you see it?

 

[gnarly]

VQ? Nope, all they w\o round-overs.
About Dualconcentric™ drivers, here it is, from sunny Bulgaria:
View attachment 561778

Is that a rebadged BMS? Sure looks like it.

 

[gnarly]

Do you mean OS in general, or just as used in a typical 2-way implementation? An OS synergy-like design will perform almost the same as a conical one below a couple kHz, assuming equal mouth size and coverage angle(s).

I meant OS in general. That said, I don't really trust any conclusions I've formed about OS, given no direct experience, either real or modeled.
If you have examples of synergy-like designs built off OS, I'd love to see them.

 

[Flaesh]

Is that a rebadged BMS? Sure looks like it.

Sure. IIRC, it was reported on Speakerplans that some early production units were fitted with ferrite 4590s Dualconcentric™; for some reason, a sufficient quantity of neo drivers was not found .

 

[bmc0]

I meant OS in general.

OS is almost the same as conical except near the throat. It follows then that the acoustic loading is almost the same at low frequencies. Can be confirmed by simulation if you're so inclined.

If you have examples of synergy-like designs built off OS, I'd love to see them.

Not any large ones, unfortunately.

 

[Duke]

Hello Duke

Can you elaborate a bit? The original JBL 476's used the coherent wave phase plug the made them "throatless" drivers. Does the Radian use the older conical triangle cross section like a 375?

Thanks Rob

The exit angle of the Radian 951 motor is 13.7 degrees (IIRC) but it is CONVERGING instead of DIVERGING. So ideally the horn's throat would have a matching converging entry angle and then would transition (hopefully smoothly) to its normal diverging horn flare.

Thank you Duke.
Without a deep understanding of the oblate-spheroid math and resultant contours, I've always kind of guessed the mouth becomes disproportionally large as xover frequency lowers. I think the info you've given supports that idea. Is that how you see it?

I think the diameter of an Oblate Spheroid generally scales with frequency, with the possible exception of the mouth radius, where smaller diameters arguably result in more compromise in the inevitable juggling of tradeoffs.

 

[HiMu]

So true. A friend's wife is a musician. His huge horn speakers are fine with her!

Plot twist: she plays subcontrabass tuba

 

[fpitas]

Plot twist: she plays subcontrabass tuba

Lol! Singer. She likes the voice presentation.

 

[Flaesh]

Radian 951 motor is 13.7 degrees (IIRC) but it is CONVERGING

My first ones were the 950s. Just a standard divergent angle. I asked Richard for the exact value; if I recall correctly, it’s 11º+.

 

[Newman]

@Tell have you read any of Floyd Toole's books? Thoroughly?

 

[Duke]

My first ones were the 950s. Just a standard divergent angle. I asked Richard for the exact value; if I recall correctly, it’s 11º+.

Did you carefully eyeball the exit of the 950, or just go by the spec sheet?

It was like pulling teeth to get Radian's help desk to FINALLY admit that the 951 has a converging, or negative, exit angle, which is what it looked like to me. And they never did answer my multiple direct questions about whether the exit angle of the 950 is also a negative angle. They just kept repeating that the data sheets had all the information I needed, which was untrue. Very frustrating. Cost me thousands of dollars because I had horns made for the 951Be based on the incomplete (and therefor incorrect) information on their data sheet.

I suspect (but do not know since I've never had one in my hand) that the 950 also has a converging exit angle.

Believe your sighted analysis of the 950's exit angle, and NOT "the published data", as least concerning whether the exit angle is converging or diverging!

 

[Flaesh]

Believe your sighted analysis of the 950's exit angle

I definetly believe. And measured it roughly myself. 950 designed just like any standard driver with a dome phragm. Richard Kontrimas himself (as Radian founder\owner) was a pleasure to deal with. Although I was dissatisfied with the professional competence of Radian girl who filled out the shipping documents in 2010 . I don't know anything about the current technical support\owners etc.