Recommended cone driver for mid horn?

[Dave Zan]

There has been a lot of discussion about cone drivers for multi entry horns but I still haven't seen any mid drivers that look optimised for horn load - with the exception of some JBLs.
Anyone know any other drivers that fit this spec.?
Basically a cone version of a compression driver.
That would typically be short coil, extended field for maximum efficiency.
Lots of inductance minimisation/flux stabilisation would be nice too, copper plated pole piece, aluminium plate on top and conductive sleeve inside.
Also aluminium ribbon voice coil (or maybe square wire if two layer inside/outside) for minimum mass to extend the top end.
A carbon voice coil former to further reduce the mass seems obvious but I've never seen this in any driver so a bit much to expect.

David

 

[AllenB]

How about this thread
Suitable midrange cone, for bandpass mid in Unity horn.

 

[jjasniew]

Many years ago a friend stopped by to tell me this church thew out their speaker system - it had been out in their parking lot for days in the rain. By the time I got there, all the drivers were gone. So I picked up two - an 8 and a 10 cell - sand-filled multicell horns. The 8 cell still had the manifold pipe left attached, but the 10 didnt - which put them well into the "now what am I going to do with these" category.

As an experiment, I did adapt a 4" cone driver to the 10 using a piece of wood with a rectangular aperture, leaving it open back. And it made sound. That's all I can recall as this was 30+ years ago - I've even lost track of what ever happened to those horns...

 

[Dave Zan]

How about this thread

I read some of that thread, it's one that I had in mind when I commented that "there has been a lot of discussion".
But it seems to have died and I don't want to restrict the discussion to "Unity horns".
Also, despite the ~2,400 posts, I never saw a driver that looked like it was optimised for horn load.
So I was left with an unfulfilled curiosity, and perhaps someone has a new recommendation.

Best wishes
David

 

[AllenB]

It's been a while since I read that thread but I don't see how the unity bit should stop you from using it in a synergy.. What does horn loading mean for you, and what about the efficiency/bandwidth product?

These drivers are run through a smaller aperture, a higher compression ratio. Isn't the ability to turn this kind of loading into pressure what makes such a driver? They tend to have higher fs to sit in the middle of the band of interest so they are efficient. Some of this can trade against size so you can fit them on the sides of the horn, or even trade off compression ratio. Mostly these are pleated surround types but this isn't a requirement.

 

[GM]

Assuming you're wanting a true compression driver for a FLH, JBL and some other prosound manufacturers have what you want, but normally not for sale except as replacement parts for clients. Quite pricey too.

Eminence night can make some for you, but don't know the minimum quantity. Any prosound manufacturers in Australia?

Anyway, DIYers usually use 'full range' single drivers to get the short coil, low Mms, Le, though no high power [compression] handling.

GM

 

[Dave Zan]

It's been a while since I read that thread but I don't see how the unity bit should stop you...

It doesn't stop me, I just didn't want to restrict the discussion- there may be "classic" horn experts/enthusiasts who never bothered to read that thread because the title restricted it to unity horns.
I also noticed that most of the recommendations seemed to be for mid/woofers- not really optimised for horn load.

a true compression driver for a FLH, JBL and some other prosound manufacturers have what you want, but normally not for sale except as replacement parts for clients. Quite pricey too.

The JBLs are sold as replacement parts but seem readily available (mostly).
They are indeed quite pricey, partly because they are sophisticated drivers with a lot of nice, but expensive, optimisations.
But some of the cost is probably JBL's extra mark-up for the brand reputation, hence my question.
I don't know much about such drivers from other prosound manufacturers, you have any recommendations?
I am surprised that none of the specialist driver manufacturers (BMS, Beyma, 18sound etc.) seem to make such drivers.

Any prosound manufacturers in Australia?

Not really anymore, AFAIK.
It has occurred to me to make a batch and see if they sell.

Best wishes
David

 

[GM]

The JBLs are sold as replacement parts but seem readily available (mostly).
They are indeed quite pricey, partly because they are sophisticated drivers with a lot of nice, but expensive, optimisations.
But some of the cost is probably JBL's extra mark-up for the brand reputation, hence my question.
I don't know much about such drivers from other prosound manufacturers, you have any recommendations?
I am surprised that none of the specialist driver manufacturers (BMS, Beyma, 18sound etc.) seem to make such drivers.

Good to know; I know obsolete stuff is/was available, but last I checked probably a decade ago, Lansing Heritage folks were trying to get at least tech docs with mostly no luck on current drivers. Then again with the way Harmon's been spending money, maybe most everything's for sale nowadays.

Agreed, what the market will bear.

Not really, I mean I see them online periodically, look at the price out of curiosity and move on since I've no use for them on DIY forums. That said, as you implied, we don't need drivers any better than good prosound in general and for stage/cinema in particular.

Note too that WGs are taking over, so only needs to be built to withstand high power at low distortion, which again is only required for prosound DIY and even then they're moving into more n' more complex BP boxes, so these folks are using the type drivers that may be of interest to you: High Order Quarterwave Society (DIY Paraflex & Super Planar dev community) Public Group | Facebook

GM

 

[Dave Zan]

...at least tech docs with mostly no luck on current drivers.

Yes, the newer drivers are short on Thiele/Small parameters and the like.
No surprise really, it's for the replacement market, not DIY.
But they are usually fine to sell them, there are a few "cult" systems where they are apparently worried about knock-off clones and won't sell crucial parts unless confirmed as replacements.
So you have to measure the T/S yourself but there is some information available in AES publications-
the 2164 here AES E-Library >> Application of Static and Dynamic Magnetic Finite Elements Analysis to Design and Optimization of Transducers Moving Coil Motors
and the 2165 here AES E-Library >> Comparative Static and Dynamic FEA Analysis of Single and Dual Voice Coil Midrange Transducers
The 2164 looks really nice, presumably the 2165 is even better but I haven't sourced that paper yet, my library has problems with convention papers.

Best wishes
David

 

[AllenB]

In order to get a good answer to your question and get down to more important issues like motors and geometry I think it is necessary to talk about the type of horn, band and some of your preferences. This assumes you've found something to fit your system, otherwise that adds to the discussion.

 

[cowanaudio]

G'day Dave

In a domestic environment I would prioritise bandwidth over maximum sensitivity. To that end I've had very good results with the BMS 6N160 and B&C 6MDN44 in multi entry horns that cross at 150Hz on the low end.

 

[Dave Zan]

...I think it is necessary to talk about the type of horn, band and some of your preferences...

Thanks for the reply, I'm not sure the lack of responses is because I wasn't specific, it seems a bit random how some threads take off.
At this point I don't have a specific requirement, it's more an attempt to find if there are any commonly available horn optimised drivers.
No point to work out details and then find a suitable driver doesn't exist.
I don't see that the type of horn has a major impact, OS profiles will load the horn less and require a bit more Xmax I suppose, is this what you had in mind?
Horn profile will be close to constant directivity, trial and error with Marcel's ("Mabat") software at this point.
Band will depend on what's available but nominally perhaps 200 or 300 Hz to ~1k Hz.

In a domestic environment I would prioritise bandwidth over maximum sensitivity...

Hi William, that's a reasonable priority but there's not a trade-off as far as I can see - Lower Qes improves both bandwidth and sensitivity.
There is some trade-off with cost of course

the BMS 6N160 and B&C 6MDN44 in multi entry horns that cross at 150Hz on the low end.

These are the sort of drivers I have found and I expect they are fine but not really optimised for horns.
The BMS has 15 mm deep voice coil but only 1/3 is effective with a 5 mm pole thickness.
So not particularly sensitive and the Qes could be lower to improve the bandwidth.
BMS explicitly call this a "low/mid driver", which looks accurate and fair.
Also reflected in the use of a heavier copper VC rather than aluminium.
The B&C has a 10 mm voice coil with a 6 mm pole thickness.
The sensitivity is better and the lower Qes should help bandwidth a bit.
But still not the best we can do.
Do you think there is any market for a horn optimised series of speakers?

Best wishes
David

 

[kipman725]

There is the 8PE21 from B&C, very little xmax low Qes (0.2). Beyma also have a a lot of drivers with ~0.3 Qes. What frequency range are you aiming to cover?

Also this page may be of interest:
Graeme's DIY pages

 

[Dave Zan]

There is the 8PE21 from B&C, very little xmax low Qes (0.2).

Thanks, the Qes looks fine.
But still copper VC and presumably (in the absence of any mention in the promotional text) round wire and no flux stabilisation either.
The pole piece shape is basic but perhaps that doesn't matter with the extremely small Xmax.
It seems to me that a thicker pole plate/shorter VC would be perfectly practical for a mid driver.
Maybe this is not done for some reason that I don't understand but I wonder if it's just lack of innovation.
Frequency limits are still to be determined, as explained above.
Thanks also for the link, I had read the section on the cone speaker phase plug before but other sections were new to me.

Best wishes
David

 

[cowanaudio]

Hi William, that's a reasonable priority but there's not a trade-off as far as I can see - Lower Qes improves both bandwidth and sensitivity.
There is some trade-off with cost of course

David

G'day David

I should have been more clear, it's the bottom end of the drivers response I want to push out as far as possible. It's easy getting to 1KHz where almost any high frequency driver can take over. I've just finished a passive crossover design for an MEH that uses a pair of 5" Revelator midbass drivers and a 19mm dome tweeter. Those Revelators are about as far from a typical horn driver as you will find anywhere with a 38Hz Fs and 0.55 Qes. These speakers can be used without a sub and system sensitivity is just above 90dB/2.83V.

My Danley Unity horns on the other hand are larger than these little bookshelf speakers and use a mid driver that is far more correct for a horn alignment. These Unity horns only get down to 300Hz and the mid drivers have to be padded down significantly to meet the sensitivity of the compression driver. I see little sense in that for a domestic environment.

Cheers

William

 

[AllenB]

I don't have a specific requirement,

Could you clarify that you are interested in a conventional front loaded horn and not an MEH?

You are interested in TS parameters suitable for horn loading in general although to some degree these become less important depending on your design. Another concern might be cone geometry and phase plug design.

 

[Dave Zan]

I should have been more clear, it's the bottom end of the drivers response I want to push out as far as possible.

OK, that provides context, the lowest I can see for my own use is ~200 Hz.

It's easy...to 1KHz where almost any...

Keele's famous JAES article has the upper mass roll-off, labelled fHM equal to 2*Fs/Qts.
So for the BMS this would be 2*89/0.47 = 380 Hz (2 places)
For the B&C its 700 Hz.
I know we can use past the upper mass roll off but it's less than ideal.
So I would prefer to use a driver that doesn't need to be pushed past that roll off.
Most of the drivers I have seen roll off before 1 kHz, at least in theory when the horn fully loads them.
For my own application ~700 Hz would probably do.

Could you clarify that you are interested in a conventional front loaded horn and not an MEH?

I can't see what difference it would make to the requirements for the driver itself?
(Assumed we compare a mid horn driver with the mid of an MEH.)
Apart from some physical constraints, it is nice for a MEH driver to be small so it can be tucked in close.
What I had in mind was to simulate both a conventional and Multi Entry Horn and see how they compared.

Best wishes
David

 

[xrk971]

I had great luck with PRV 5MR450NDY in a tractrix.

B&C 6MDN44 is also really nice - don’t use it above 2k though.

 

[cowanaudio]

I know we can use past the upper mass roll off but it's less than ideal.
So I would prefer to use a driver that doesn't need to be pushed past that roll off.

Almost any decent mid driver in a horn will have significantly higher sensitivity in its mid band than your compression driver at 10KHz. Why not pad it down with a broad R//L//C notch filter, like I do? This extends the bandwidth in both directions.

 

[SpeakerBob]

I know the OP said cone driver but the community 4" compression driver seems perfect for the required bandwidth.

https://www.communitypro.com/sites/default/files/M4.PDF

I was going to suggest the JBL LE-5 driver but it only got down to 500Hz on my Edgar midrange horns.

Rob.