Pro mid-ranges or compression drivers in home hifi?

As background, I'm planning a pair of 3-ways for typical home use; maybe 90db with 105db peaks or a little more. They'll either have a wide mid-range driver (something like 400-600hz to 4khz-6khz) and a tweeter, or else a single driver covering both mid-range and high frequencies (essentially a mid-tweeter). Pro drivers may potentially have some attraction for both options:
  • I'd be happier to cross my (scanspeak 10") bass drivers to fairly small mid-ranges 'if' they had the type of dynamics that sensitive and high power pro drivers posses, and they should also suffer fewer concerns over power compression. To my surprise there do seem to be pro mid-range drivers down to 5" or even 4" these days, and a few brands (such as faital pro) even seem to be easily available here.
    .
  • Or, as an alternative use of pro drivers in home hifi, it has been suggested that a compression driver in a horn would serve as a mid-tweeter, again without suffering much power compression and potentially having better dynamics than small domestic (wide/full-range) drivers used as mid-tweeters. Though the approach slightly misuses most compression drivers, on the basis that lower (home) levels of excursion allow them to play lower frequencies than intended. Seems reasonable, though some suggest their distortion may not be as good in this application, and I wasn't intending to spend several hundred £/$ per driver for anything monstrous or exotic.
My problem is that I've very little experience of using pro drivers in DIY so struggle to evaluate both possibilities. The cone mid-ranges aren't much different in principle to cone hifi drivers but they are intended for a different application, whilst compression drivers would be very new ground for me all round. I realise that in both cases size (cabinet volume for the midrange, and horn dimensions for the CD) might be bigger than wished. But what are the other disadvantages and/or advantages of (mis) using pro mid-range and compression-drivers in these kinds of home hifi situation? Good idea or not?

Thanks,
Kev
 
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Thanks everyone.

This appears to concern you? It's good that you can bring a crossover frequency down, but your waveguide needs to be up to the task.
Thanks, I'm just beginning to realise that the waveguide or horn would be quite so crucial. I've used waveguides on tweeters in the past, but just small things used mainly to tweak the dispersion; those used with compression drivers seem much more important, and so something I need to learn more about.

It isn't that I'm concerned as such, at this stage I'm just trying to decide if I should be, or if so then what about. Obviously pro drivers are very capable, and I'm much more interested in performance than boutique names or marketing. But of course it isn't 'necessarily' a given that designs optimised for high efficiency and power handling must also be ideal for use at lower SPLs and frequency ranges than intended.

For example, I've seen it said (in various ways) that pro drivers don't often match the refinement of good hifi drivers used for hifi (e.g. compression drivers sounding a bit coarse and shrill, cone drivers with erratic response or break-up etc). Such opinions might well be audiophile delusions, or there could be some truth in it; only some of these things can be checked out from specifications offered. Or it could reflect poor implementation, which is also of interest for me to understand.

Cheers,
Kev
 
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Compression tweeters have no problem with refinement or harshness. They perform the same at low levels as at regular levels.

What you get out of them depends on how well you understand their usage. It's not as simple as screwing a dome tweeter to a baffle and high passing it. They can sound bad if used incorrectly.
 
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Superb, thank you both.

I think then that the next step is to learn more about horns and waveguides in general, as well as their pairing with compression drivers and how to implement these. Not somewhere I've so far been with DIY-hifi so should be interesting. I'm already interested in managing dispersion, so have been curious from that point of view too.

The three-ways mentioned are intended to compliment/contrast my near-field listening, in times when I want bigger/room speakers with more kick. So whatever the final choice of methods, there is a very good chance that I'll go with some pro drivers of some kind.

Cheers,
Kev
 
I'm using 18Sound NSD1095 compression drivers in my current HiFi speakers. They're running >1kHz, covering the HF in a 2.5-way design, with 2x Seas H1252-08 below.

The sound is excellent: since the tweeters are intended for high-quality PA use, at domestic SPLs they're cruising along with very little stress. The sound is very clean, and doesn't get "shouty" as ribbons/domes often do when they're getting pushed and the THD starts to rise.


For compression drivers specifically, the pros/cons are as follows:

Pros:
  • Very high sensitivity
  • High power handling
  • Options for lower crossover points compared to direct-radiators
  • Controlled directivity


Cons:
  • Frequency response will be non-linear
  • Impedance curve can make passive crossover design more of a challenge.
  • Cheaper HF drivers can be rough >10kHz.


The NSD1095s are excellent drivers. Their high-tech motor etc puts them a step above the B&C DE250s I was using previously.

Chris
 
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Compression drivers are way more expensive than a good mid and dome tweeter and need correction to sound flat neutral, but when done right it can be better (due to the fact you drive them very softly and have tons of headroom). The biggest difference is in dispertion i think, where the horn (when used right) gives a more controlled dispertion than a cone mid and dome tweeter. if that is good or bad is subjective and case depending.

I plan to do such thing with a scanspeak 26W (10" woofer) and a Faital HF-201 (2" compression driver), but i'm still considering what horn i will use. I need a horn that can load to 700Hz and have a few options for it, but i'm still studying it. I will use a dsp (MiniDSP Flex) to do the crossover.
 
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Do you have in mind some horns/CD combinations for second option?

FaitalPro LTH102 horn looks interesting. Alu-cast tractrix. It should be better than usual plastics and tractrix horns are known for natural sound. Bandwidth 800-20000Hz. Dimensions 7,5x9,5in are ideal for matching with 10in woofers.
Matched with FaitalPro HF103-8 driver total cost is around 250 Euro per cabinet. Not cheap but still resonable when compared to first (3 way) option with midrange, tweeter and additional XO components of comparable quality.
Recommend XO for HF103-8 is 1,3 kHz, but to match 90 dB efficiency of home HiFi woofers you need some heavy attenuation and that greatly increases power handling and reduces distortion, so lower XO like 900-1000Hz shouldnt be the problem.

https://en.toutlehautparleur.com/horn-faitalpro-lth102-1-inch-9-25-x-7-44-inch-front-face.html

https://en.toutlehautparleur.com/compression-driver-faitalpro-hf103-8-ohm-1-inch.html
 
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Thank you everyone, this is all very helpful. Quite promising too.

There'd be some flexibility with the impedance curve and flatness correction, as I'd probably be using active crossover(s) and PC-based DSP of some kind. The cost of good compression drivers isn't ideal, but in an active system being a 2-way rather than 3-way would offset some cost and complexity too.

Waxx, your plan is very close to one of my options so it'll be interesting to hear where that goes, and any discussion around it. Such as Davor's alternatives and AllenB's comment about loading frequency versus the waveguiding requirements. I interpret this to describe the effective range of the horn's operation, between loading at the low end and ability to still guide higher up?

Thanks,
Kev
 
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Great thread topic!

I started out with JBL 2435Be's on 1200 - 11000'ish. Upper mids I call them. Had them on conicals early on, and then 550Hz tractrix horns.

On mids, 350 - 1200'ish I've had JBL2482s for over 10 years.
Again on conicals for the early stages and then tractrix.
I borrowed some
BMS 4592ND 2" dual Coaxial Neo Compression Driver, couldn't get on with them doing both mid and upper mid.
Then tried BMS 4592 Neo (not dual). They were good, perhaps as good as the 2482s in some staff. But some of the tonal qualities of the JBLs convinced me to keep them.
They would dig even deeper on a larger horn, but 350Hz integrates well with my mid bass horns.

I used the JBL 2435be's for a year or so, then got some Vitavox S2's. I had them refurbed by Vitavox in Bristol UK.
The latest diaphragms etc.
I'd listened to them a few times in other systems and knew they were my end game.
They do that frequency range, how I want to hear it.
I use a 3uF cap XO (Romy the Cat thing), which miraculously smooths their annoying shrill peak out, and brings them in at around 1200Hz!
Their speed / dynamics and tonal quality was a big step up over the JBL 2435be's.

I've had them 10 years or so.
Never thought to change.

More recently I made a pair of soft wood 550Hz Le Cléac'h horns for them.
Fine sand finish on them apart from the immediate throat.
Match made in heaven!

I don't have the pocket or energy these days to try Tad / Goto etc.
I'm sure they are nice 🙂

I love horn systems with compression drivers on this frequency.
 
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I interpret this to describe the effective range of the horn's operation, between loading at the low end and ability to still guide higher up?
Not at all. The waveguide works better at both lower and higher frequencies. (Thirdly, loading horns often have a group delay spike that can make it challenging to take them low.)

I've devised a generic example comparing two horns, one is better as a waveguide and one loads more (the more curved one).

ka1.png


However loading isn't necessary in a domestic setting. Loading is not connected with how well the device controls the wavefront. You don't hear it where it does and doesn't load, or where it changes.

For completeness I've included their loading. Here one loads strongly to below 1kHz (the solid black and red traces) and the other fades above 1kHz.

ka2.png


This next screenshot is the beamwidth. The closer to conical profile keeps control down low (the pale trace), where the loading horn has already given that up and gone wide. The loading horn goes too narrow at the top end.

ka3.png
 
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Gosh, thank you for the education, it is very kind of you to take so much trouble!

You'll no doubt have noticed that I struck-through my "higher up" phrase after dimly realising things went further, but I'd obviously not appreciated the extent of it. Nor had I understood the loading in this case; either the reduced usefulness of it or the implications on waveguiding. I've obviously got quite some learning ahead of me, this should be interesting!

Thanks again,
Kev
.
 
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Thank you. Yes an efficient/pro midrange is still very much one of my favourite options. I too like good sized drivers, for their dynamics and lower excursion. Though depending on how high I want them to go before break-up or excessive beaming, I might need to go somewhat smaller than 10" for this project. In fact my bass drivers are only 10", which is possibly a limitation that I should consider removing, but they are quite nice and it would be a shame not to use them.

In the mean-time I've been doing more searching on compression drivers and am still happy that they would do exactly what I wanted (with some eq/dsp). There are many pleased reports on diyaudio and I see that some drivers are even officially rated quite low even at fairly high SPL let alone at home levels. Reasonably expensive but not unobtainable with saving up and working more overtime (such as this one, as a random example).

The main challenges seem to be getting their implementation right - there appears to be quite a lot to potentially get wrong, both in the driver & horn matching and especially in terms of integration with the other driver(s), which is a little intimidating for a novice with them. Also the size of horn/waveguide I'd like is going to be fairly large, if I want to cross low. Neither of these are deal-breakers, though the familiarity and compactness of traditional direct radiating midranges seem simple by comparison.

It might just come down to how well I feel that I personally could handle the integration; either way I've not been put off the use of pro drivers in one way or another.
 
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Hello Kev06,
i would like to share my experience with you. I used many many years ago the Fostex wood horns and the Fostex super tweeters, but there was a design flaw with the coupling of the bass speaker to the wood horn that ruined the performance of the system and for many many years i gave up with horn drivers and waveguides. After many years listening at low volume levels with small conventional speakers i decided some years ago to give the horns approach a chance again. I posted my project here:
https://www.diyaudio.com/community/threads/ultimate-open-baffle-gallery.123512/page-207#post-7356769
and posted a small update here
https://www.diyaudio.com/community/threads/ultimate-open-baffle-gallery.123512/page-208#post-7363149
The big construction is optically dominating the listening room completely, but i am totally happy with the result, especially the performance of the 16 inch tractrix wood horn with the 1.4 inch B & C DCM 414 compression driver is far beyond my expectations. But i have to say that without quite serious measurement equipment and a complete active setup with a 2 X 4 miniDSP HD and two Hypex FA123 plate amps i wood never been able to setup the system right. I spent some additional effort to find the right power amp for the 113 db / meter efficient mid horn - only the Hypex plate amp and some attenuation with resistors made it, all other approaches led to audible noise with the very high efficiency of the mid horn.

Hope it helps,
Stefano
 
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