Best midrange driver, 4-way?

[daniels]

I have been building loudspeakers for quite some time now (fifteen years!?) and has usually been crippled by limitations of the listeners HiFi cave.
But now I have been given some loose boundaries and I want to build a construction I have been working on for some years now.

I have measurement tools to do all common measurements and T/S parameters of drivers.

My loudspeaker constructions have so far been built on some very good experience with the following drivers:

High range:
1 x Scan-Speak R2904-700000, 1” Dome. (approx. 7kHz-x, 6db/octave).

Upper mid-range:
1 x Accuton C2 44/8, 2” ceramic driver. (approx. 1,5KHz-7KHz, 12dB/octave).

Lower mid-range:
? (approx. 100Hz-1,5KHz, 12dB/octave).

Bas:
Scan-Speak 1 x 26W8861T00 (approx. x-100Hz, 12-24dB/octave).
or
Peerless XXLS (830847) (approx. x-100Hz, 12-24dB/octave).

The working frequencies are only guidelines so far but I would like to find a pretty broadband middle range driver. From the above you can see it is a four-way loudspeaker I am aiming for.
Each of the drivers has some qualities I really like. I am not entirely set on the Scan-Speak 26W8861T00 yet (in closed enclosure). If I go for it I will probably use two on each side. But two 12” Peerless XXLS (830847) in each side is scheduled for testing as a possible replacement (closed enclosure).

I already have acquired the drivers listed above but I am having problems deciding on what to use as lower mid-range… SOMEONE HELP! 

I have these drivers lying around and just waiting to be tested:
Audio Technology 6”
Audio Technology 8”
Scan-Speak 18W8531G00

But I am not sure if one of these drivers can do the proper job or I have to go for a different driver. Off course it would be nice to be able to use one of the drivers I already have in possession, but if there is some driver out there that does a better job then perhaps that’s the way I should go (?)

So after all this chit chat it all comes down to;

Which lower midrange (high-end!) driver can YOU recommend?

And for the bas; Scan-Speak 26W8861T00 or Peerless XXLS (830847) bas driver?

[Jed]

From the range of 100hz to 1k nothing can beat the Seas Excel W22EX- Especially in an open baffle. Some of the best sound I heard at RMAF came from that driver. No wonder the Orion has such a cult following. Simply stunning mids.

I've got a pair of Seas W15CY mids coming this week to try out, but I think for your application the W22 will be world class.

Nice collection of drivers by the way and I don't mean to add another pair of drivers to your audition list but I feel that strongly about the W22. Maybe I should take my own advice some day.......nah that would be too easy. :W

Jed

[John D]

The Seas W22 would indeed be a very fine choice as a low mid. However, why not go a little bigger and use the Scanspeak you intended as a bass driver as the lower mid? That would mean even lower distortion: definitely something you want in an ultimate speaker project like this :T !
The Peerless is a very fine driver for low frequencies and I'd choose it over the Scan for this range. However, why not try something even bigger here, too? It simply is a fact of nature that bigger drivers need less excursion for the same sound level, which means they stay in the range where they are most linear.
The CSS SDX15 looks nice!

[JoshK]

I am no speaker designer, I am just learning, so take my thoughts with a grain of salt. What you call upper midrange, I tend to think of as lower treble. But semantics aside, wouldn't it be easiest to choose to cross over near the baffle-step, which tends to be around 800hz for a typical speaker? If you chose your upper mid/lower treble driver to cover 800hz to 6k-ish it would seem to make life easier and also keep the crossovers out of the ear's most sensitive range.

That said, the W22 is also what I thought of when I first read your post.

[Jonasz]

The Seas W22 is the obvious candidate here, not sure it will do 12dB though? Maybe the Seas W22 Nextel could work?

[Paul W]

The W22 is my favorite low-mid, but agree a 12db xo may not work well with the high W22 breakup. If you want to stick with 2nd order, maybe the 8" AT you already have...or even the 8" Peerless Exclusive. 4th order with a W22/Accuton 44 might benefit from a little lower xo than 1.5k.

[daniels]

It seems like the Seas W22 is supported by the majority.
I actually considered one of the smaller W18 or even W15 as a possibility but I have no experiences with Seas. Somehow just about every Scan-Speak driver has crossed my path, several Vifa, Peerless and AudioTechnology but never Seas. Looks like there is no way around Seas for my project :-)

@John D
The problem with the Scan-Speak 10” 8861T00 is that it only sounds good until 4-500Hz (recommended fs-600Hz), then it sounds a bit slow hitting those higher frequencies (man I hate describing sound! ).
And the Thiel & Partner C2 44/8 is only recommended down to 1000Hz (with minimum 12dB filter).
That leaves me with a “hole” between the two drivers.
I am really trying to hold myself back from creating a monster speaker, and I did start out with only one 8” woofer for the system and then upgraded to a 10” woofer and did eventually consider the AudioTechnology FlexUnits 15” woofer. But I have to stop somewhere and have decided that if I need more bass, than what the 10” Scan-Speak or the 12” Peerless drivers can provide, then separate bass-sections will be added.

@JoshK
I just call it upper mid-range because the Thiel & Partner C2 44/8 covers frequencies from 1KHz-12KHz (recommended) and that is (in my opinion) half and half of mid-range and lower-treble. But I could just as well call it lower-treble as you mention.
The crossover frequencies have not been determined yet and I have to wait for measurements of the beta-version. But the drivers have pretty fixed operating frequency ranges so I am limited to what they do best. But from earlier experiences, I believe they are very close to the best I have ever heard in their respective frequency ranges.
The Seas W22 would certainly do the job when it comes to T/S and frequency specifications.

@Jonasz
Would you use a steeper filter?
I have an idea of trying an all 6dB filter for all drivers. Just to see what the measurements show and what it sounds like. If it is even possible at all (?)
I will off course try out many filter possibilities but my favorite filter has always been the 6dB and 12dB. But I have got some idea about a 24dB filter.

@Paul W
Could it a better idea to use a smaller W18 or even W15 for my construction?
A recommended 24dB crossover at 1,5KHz tells me that the W22 is not a very broadbanded driver.

[TacoD]

The best driver I have used are from Audiotechnology.

In your driver line up I find it strange you want to combine a Scanspeak 7000 with a Thiel & Partner. The Seas W22 is a great driver but does not match the other driver soundwise (paper Scanspeak)

So I would suggest use Peerless bass/ Seas W22 with Thiel&Partner and different tweeter. Or use Audiotechnology 6" (is it the 18H or the Flex 6"), Scanspeak 7000 & Scanspeak 8861. And maybe the Audiotechnology 8" as filler.

[69Stingray]

CSS FR125 4.5" (papercone)? If I recall, excellent distortion until you get below 300 Hz. With the extended freq. response, should be an easy X-Over to the Low-Treble.

[daniels]

@TacoD
The combination was made entirely on listening tests. I find the Accuton (Thiel & Partner) to be one of the best sounding drivers in its frequency range. And the Scan-Speak R2904/700000 is the best dome/ringradiator money can buy at this time. I do have a ribbon driver I want to test (http://www.dynasonic.gr/), but I do not think there is much out there which can compete with the R7000 driver (perhaps some Accuton ceramic tweeter drivers?).
You mention a problem with the Scan-Speak being a paper coned driver versus the Seas driver. You think that is going to be a problem tonal wise? I do not like drivers with a certain tonal characteristic.
If I use 2x12” Peerless XXLS drivers with a 6” AudioTechnology FlexUnit and the Accuton 2”, should it not match up with the R7000? I am going to set the cross over quite high, perhaps 7-9KHz, that should make it easier to integrate the R7000 with the Accuton, or what is your argument for finding another tweeter?
Are we looking at ribbon tweeters?

@69Stingray
I am a little concerned about the output of such a small driver compared to the other drivers. If it is going to be paired up with 2x10” or 2x12” woofers, I do not think it can live up to the task – perhaps at lower SPL.
And it has to go below 100Hz if it is going be cross over at for example 200Hz. Otherwise I am forced to use steep filters which I intend to avoid (if possible).

[Paul W]

If you look at Excel response curves on the Seas site, you'll see metal cone breakup from about 4k to 9k, depending on driver model. The breakup must be notched and even then, if xo frequency is too high and slope low, the resonance may still be audible. Personally, I want the ringing 40-50db down which would be tricky to achieve with a 2nd order at 1.5k with the W22. IMO, 4th order at 1k is closer to ideal for the W22. Done well though, the W22 will reward you with exceptionally clean, uncolored, sound.

As you can see in the Seas graphs, going to a W18 or even W15 wouldn't change the breakup frequency by a tremendous amount considering how much harder they would be driven on the low end...so I'd stick with a larger driver for the low-mid. If you want to use low order filters, consider the softer cones like the Revelator or AT you have on hand.

[daniels]

@Paul W
I am going to make some effort in getting that W22 driver into my lab.
My plan is to build a box for each driver which I can stable on top of each other. That way I kan easily swap a driver in the chain and continue measurements and listening tests. Then I can match the W22 with my AT FLex6", 8" and SS 18W drivers.

In the end it will be my ears, not my eyes and microphone, who decides the winner.


Still, all inputs are welcome!

[TacoD]

In my experience the sound of the Scanspeak paper woofer is not as neutral as the hard cone woofers. The Scanspeak 7000 is nice, but a good ribbon (Raal) or planar tweeter (Stageaccompany, Raidho, or build your own) has even more detail and dynamics.

If your experiments show that the Thiel&Partner is a good match then go for it. There are a lot of possible configurations possible. In my opinion you do not want to mix different concepts. Simply combining the best drivers is no guarantee that you will end up with something better than the sum of all parts.

[daniels]

@TacoD
I am getting second thoughts about the mix of drivers.

I could save the Thiel&Partner driver for another ribbon project I have planning and make the combination like this:
R2904/700000
AudioTechnology Flexunits 6"
Scan-Speak 26W8861T00 10"
- A "simple" 3-way solution.

Even though I have been building loudspeakers for fifteen years by now, I am still uncertain about which drivers are best together.

[TacoD]

It will be a very nice 3-way! I've done a similar 3-way myself and I think you will not be disappointed.

Driver choice depends also on personal taste. In my experience it helps to look what others do, and try to listen to a variety of loudspeakers.