Compression Drivers

[Bigun]

Mark,

I'd be interested in your thoughts about compression drivers/horns as they compare with drivers like MA?

I'm interested in your opinion not because I want to pit compression drivers against direct radiators but because you have considerable understanding of speakers in terms of their technology and how to refine them for the most realistic sound. Good horn speakers are said to be very realistic. MA drivers are also said to be very realistic. I'd like to start from the premise that one is not better than the other. But they are quite different and in seeking to learn I'd like to know what you have to say about the comparison ?

 

[markaudio]

Mark,

I'd be interested in your thoughts about compression drivers/horns as they compare with drivers like MA?

I'm interested in your opinion not because I want to pit compression drivers against direct radiators but because you have considerable understanding of speakers in terms of their technology and how to refine them for the most realistic sound. Good horn speakers are said to be very realistic. MA drivers are also said to be very realistic. I'd like to start from the premise that one is not better than the other. But they are quite different and in seeking to learn I'd like to know what you have to say about the comparison ?

Hi B,
I'm in Heathrow airport waiting to board a flight to Shanghai so have some time to kill. I'm not sure how to answer your enquiry as the comparison you seek is near impossible to calculate or assess.

I have been asked if I'd design and build a compression emitter. Its unlikely. As a Mech Eng., I have concerns relating to the loadings on small radiating components but freely admit that I've spent little time studying this type of system.

In terms of acoustic performance, its a matter of personal taste as to which driver types and system designs suit an individuals needs.

Thanks
Mark.

 

[Ivo]

Well, since you're an engineer, no doubt you will feel challenged and intrigued by the technology at some point... ;-)

 

[markaudio]

Well, since you're an engineer, no doubt you will feel challenged and intrigued by the technology at some point... ;-)

I've landed in Shanghai, more time to kill waiting for the onward flight.

I don't feel "intrigued" by compression. Having listened to several systems over recent years, its output is, I feel, an aquired experience; Freely appreciating that some users much like the compression acoustic performance.

At this point in loudspeaker driver development, there's little on the horizion that I can see to overtake the common transducer concept. Its effective for most (if not all) types of requirements. I remain a "believer" in single-cone, extended range, low mass designs. They encompass a family of material, production and operational properties that may prove effective in supplying future acoustic needs in a world where resource management will become increasingly critical.

40 mins to catch my next flight.

Cheers
Mark

 

[Studio Au]

Sadly my conical horns with Radian 850pb's are not really set up properly and need lots of active crossover work to get them sounding good, and perhaps a supertweeter as well.

But last week I spent a whole day listening to My Bookshelf Alpair 7's Pensil esc 10's and some 4.5" BMR drivers sat above a big pro woofer.

So no fair comparison for judging, and no test equipment, but the Alpairs won the day. 7's for pure speed, airiness and top end, I still think the 10's offer the best of both and are able to go as low as I need, while the BMR driver (almost electrostatic in principle) had amazing clarity, and dynamics but got a little ragged when played loud (at full range). The Radians (3" voice coil 1.5" exit) had great breath, and seemed the fastest and most capable, but a bit ragged at the very top, and so needs good integration with a woofer and perhaps super tweeter, and because of the horns needed, directivity is what its all about and unless you have a music room and a single seat then for me that becomes a problem. Not only for placement, and seating position, but of needing it to be a multi way, with all the inherent problems that can bring.

I'd like to hear the Geddes speakers soon, and see how they compare to a really well built, well run in, and well amplified Alpair 10.


Just my 2 cents.

 

[Bigun]

I do agree that for direct radiators, low mass seems to be king. It reduces the impedance mismach between the cone and the air.

 

[mlee]

Not too much to add here. Below is based on listening tests and not scientific at all and only in one room.

I've directly compared (more listened) the Radian457pb and DE250, both in QSC and SEOS-15 waveguide against the Alpair 7.3, 10.3 and 12p. Bottom was 15tbx100 and vifa NE265W. Crossed over to FAST with the Alpairs. Alpairs in BR and one superpensil. Tried different combinations.

The Alpairs really show the problems with the crossovers. On one hand the directivity of the horn seems to present the highs differently than the alpairs. Comp drivers and horn "seems" a tad more spacious and open. Then comes the dreaded crossover. When listening to the Alpairs more coherent and of one piece. Switching between the two really shows how bad a crossover can be if it is not very very good. The superpensils go deeper in my room than the 15tbx100. The 2-ways go louder. Seems like a choose your demon.

The one conclusion that came out of this is I suck at crossovers. There is something to be said about a fullrange with good gear. It takes some crossover experts to do passive correct with compression driver and horn in the 1k-2khz range. Even with active crossover I think the above holds true but shortens the gap a bit.

Note sure if this helps.

 

[Bigun]

what attracts me to compression drivers is their potential to be much more efficient when horn loaded, along with their reputation for excellent dynamics. This thread wasn't aimed as a direct vs horn debate - but as said above, I think Mark has some skills in driver design that are clearly world class and he's brave enough to use them to advance the art. Imagine if he took that attitude to the compression driver camp too .... maybe the first step would be a driver for a BLH - oh wait, we have the FH3 already

 

[Rullknufs]

Or how about air motion transformers such as the Beyma TPL-150 AMT?

 

[Scottmoose]

I wouldn't hold your breath. I suspect MA have roughly the same amount of interest in AMTs as they do in tattooing crocodiles. Which is not to say the TPL-150 is anything other than a superb driver (it is).

 

[chrisb]

Indeed, while Mark and crew are competent enough engineers, why would we entreat them to embark on something completely different than that which they do extremely well?

Don't get me wrong, I've heard (& built) several excellent systems with AMTs but I think the device type is best described as a completely different animal .

 

[markaudio]

Hi Chaps,
Thing to bear in mind is that cone/emitting surface acreage is always a fundamental element in transducer design. The guide is: Smaller emitting surface areas deliver a narrower band of frequencies. They also (subject to mass, profile design and driven loads) run an elevated risk is emitting increased distortion.

Its really tough to get the right acoustic balance from a compression driver. They inevitably create a particular sound characteristic that naturally is pleasing to some ears. But its difficult to break away from the laws of physics to hope that small emitters replying on a wave expansion will offer a practical alternative for most users when compared to more standard driver design/types.

For me to invest time and resources into making a compression driver, much as I'd enjoy the technical challenge, isn't likely viable. I should never say "never". Perhaps with lady-luck on my side, one day I'll be able to explore compression drivers more fully.

In the meantime, its interesting to read various thoughts of members on this and similar subjects......thanks for making these efforts.

Cheers
Mark.