Compression driver comparison

[Aardvark87]

I'm trying to decide between two compression drivers. I'm not looking for max SPL comparison, but sound quality.

Shootout is between B&C DE780TN and Beyma CD14ND.
My experience so far shows me that I don't like the sound of Ti diaphragms, so I'm specifically looking for that effortless HF reproduction with fast transients and no metallic fatiguing hiss/harshness.

B&C DE780TN (Ti diaphragm)
https://audioxpress.com/article/test-bench-b-c-speakers-de780tn-8-compression-driver

Beyma CD14ND (proprietary PM4 polymer diaphragm)
smaller 1" exit brother tested here:
https://audioxpress.com/article/test-bench-beyma-cd-11nd-compression-driver-and-td-194-horn

So I would expect the CD14ND to have a cleaner waterfall graph. But comparing the DE780TN with the CD11ND I'm slightly confused to see that the Beyma seems to have more HF resonances (around 9kHz and 15kHz) than the B&C (around 15kHz and 17kHz). Overall the decay time is longer for B&C though.
What's to be concluded from that?
Does anybody have some experience with a Ti compression driver that is not fatiguing?
Am I being too dismissive of Ti diaphragms?

 

[AllenB]

If it's CSD you're looking at that way, it hardly seems helpful that they've not equalised the responses or used a horn that isn't resonant.

 

[Aardvark87]

So these streaks could be horn resonances?

 

[AllenB]

To some degree yes. Look at the response as well, there is a large peak that will extend the decay like that, but it might be the kind that is OK once it's equalised. How do you tell?... The testing conditions should be set for a fair comparison.

 

[manuataahua]

In my experience ring radiator CD have that clean, effortless upper end you are looking for as the geometry of the diaphragm pushes the occurrence of break-up very high or out of the audio spectrum. The downfall with this technology is that they normally need some EQ applied as their FR has got low Q bumps and crevices that you cannot leave untreated.
https://audioxpress.com/article/test-bench-the-bms-1-5530nd-high-efficiency-compression-driver

For standard CD, some references from Eighteensound have a treated Ti diaphragm that helps with HF uneven-ness:
https://audioxpress.com/article/test-bench-a-1-4-pro-sound-compression-driver-from-eighteen-sound

Also there are composite diaphragms that seem to help in the upper end but I haven't heard them myself, for instance:
https://audioxpress.com/article/test-bench-eminence-n314x-textreme-compression-driver

Both of the drivers/horn combos you proposed seem quite resonant and I believe it would be hard pressed to deduce from the measurements which one will be nicest to listen to. But if you know from experience that you find the Ti drivers too bright and tiring, maybe try something else.

 

[Aardvark87]

@AllenB
That makes sense, EQ it flat and then it's a fair comparison.

@manuataahua
that's really helpful, thanks! The BMS 5530ND looks good, very impressive clean response and quite low. Looks like crossing it over around 1.2kHz will be no problem. The others you list here also look good and it's nice to see a Ti diaphragm showing low distortion. TiN-coating makes a lot of sense, I've worked with that material actually (thin film coating) and its properties are incredible. I hope B&C will adopt this.

 

[AllenB]

That's right.

There is also a bonus aspect to this realisation and that is that you shouldn't accept a comparison unless they have been EQed. If you say one sounds good but it has a different response then you can't be sure what you're listening to. There are other differences as well.

 

[Rewind]

From what I have heard in my listening tests, 3" aluminium diaphragms are tough to beat. Thinner aluminium if above 1200hz. Thicker aluminium if 400-500Hz is the goal. Now which brands has these? I believe none that are manufactured today.

 

[weltersys]

Aluminum surrounds fatigue and crack much sooner than titanium or polymer, especially when used below 800Hz.
Most HF drivers are made for the PA market, where longevity with high output is important, so the use of aluminum has mostly been abandoned.

That said, Radian still makes aluminum alloy aftermarket diaphragms, and their own drivers using aluminum & Mylar plastic surround diaphragms.

 

[indianajo]

https://audioxpress.com/article/test-bench-the-bms-1-5530nd-high-efficiency-compression-driver
https://audioxpress.com/article/test-bench-a-1-4-pro-sound-compression-driver-from-eighteen-sound
https://audioxpress.com/article/test-bench-eminence-n314x-textreme-compression-driver

Anybody know any tests like that run on Peavey RX22 1.4" titanium driver? Bing can't find any, just vendor "star" ratings. (amazon, zzsounds). I have some RX22, like what I have, wonder how they stack up? Some internet lore about them "quacking" at high volume, which is not how I use them in the music room. 1/8 th to 70 watts only.
Also I would buy an N314X for test if I could find a 14"w x 7"h x 10" deep bolt on horn for it. Multiply by 2.54 for you metric fans. Peavey horns are screw on. That tiny horn eminence sells is not competitive, and horns that project up & down as much as they do wide strike me as totally stupid. I have acoustic panels up & carpet+pad down to damp those reflections. I'm building some ugly copies of my SP2(2004) 2 ways, since burglars find their pawn shop value so attractive. Two pairs stolen in 2020. I do walk around the house with the music on, so wide dispersion is a plus.

 

[phase_accurate]

That tiny horn eminence sells is not competitive, and horns that project up & down as much as they do wide strike me as totally stupid.

The stupid fact about horns that promise to have a horizontal coverage that is wider than their vertical coverage is that they often suffer from pattern flip.

Regards

Charles

 

[KJ_Knowles]

Aluminum surrounds fatigue and crack much sooner than titanium or polymer, especially when used below 800Hz.
Most HF drivers are made for the PA market, where longevity with high output is important, so the use of aluminum has mostly been abandoned.

That said, Radian still makes aluminum alloy aftermarket diaphragms, and their own drivers using aluminum & Mylar plastic surround diaphragms.

I have always found the Radian drivers to be among the better sounding and well behaved (within their intended bandwidth) drivers. Their coaxial drivers have found their way into a number of commercial high end products over the years. If you have piles of money you don't know what to do with, they have Beryllium diaphragm options. I've never had the privilege (funds) of working with those. 😉

 

[weltersys]

Anybody know any tests like that run on Peavey RX22 1.4" titanium driver? Bing can't find any, just vendor "star" ratings. (amazon, zzsounds). I have some RX22, like what I have, wonder how they stack up?

The Peavey RX22 has a 2" diaphragm (not 1.4") with more Sd than the BMS 5530, less than the Eminence N314X.
Stacking up, you could expect the RX22 to perform better below 1kHz than the BMS 5530, but not as well as the 3" diaphragm Eminence N314X. I'd expect either to perform better in the upper range, just from looking at Peavey's cut sheet.

 

[Rewind]

Aluminum surrounds fatigue and crack much sooner than titanium or polymer, especially when used below 800Hz.
Most HF drivers are made for the PA market, where longevity with high output is important, so the use of aluminum has mostly been abandoned.

That said, Radian still makes aluminum alloy aftermarket diaphragms, and their own drivers using aluminum & Mylar plastic surround diaphragms.

Radian is not my favourite, but I might end up with it as the only option left. Right now I am into 80’s drivers from Yamaha and Renkus-Heinz. Yamaha can be a bit boring but correct, and goes deep. Renkus Heinz can be wonderful with its thin diaphragm, but far from flat repsonse.