Subjective impressions of CSS fullrange drivers?

[FullThrottleRic]

Hi everyone,

I wasn't sure if I should put this in the fullrange forum but thought I'd get a better response here.

Does anyone have any experience with the CSS WR125S and FR125S full range drivers used as midranges, and how do they sound compared to the likes of SS/Seas's ect smaller drivers?

For my next project I'm going to need a driver to mate with a pair of Seas W18NX-001's at 400Hz or so and my SS 9500's at the top end.
The CSS drivers are pretty low sensitivity (85db/w) so idealy I'd need 2 per channel in parallel, so the price will be similar to a single SS/Seas driver.

The other alternatives I quite like the look of are the Seas M15CH-002 or M15CH-001 (which I've heard very good things about) if I can find somwhere in the UK that sells them.

Finally if I do go for the CSS drivers, am I best going with a TMM or MTM layout? One advantage they have over the Seas mid's is I'll be able to cross them to the tweeter reasonably high which should reduce tweeter excursion/distortion. But if I use them in MTM configuration with a high crossover would this cause problems with the drivers centres being more than a wavelength apart at the crosover frequency?

Suggestions/comments? 😀

 

[rabbitz]

IMO the FR125S sounds best when used by itself as it's a remarkable fullrange driver.... it's the only real fullrange I've heard that covers the frequencies from top to bottom on most music that I listen to.

I've tried a hybrid using the Peerless 830875 for the bottom and was very sweet but couldn't match the single fullrange for involvement and sonics (point source and no phase problems?) but did increase power handling immensley.... gain one thing and lose another.

http://www.rzaudio.com/rz52/mongrel.htm

I'd go with a single Scan Speak or SEAS mid if doing a 3-way as the FR125S would be wasted.

 

[FullThrottleRic]

Thanks for the reply 🙂

Fair enough, I'm building them more fot HT so high output it quite important; I doubt a single FR125S per channel will go loud enough for me 😉

I see you sell Peerless and SS drivers on your website, could I fire off a couple of questions?

I'm planning on using a downfiring XLS10 down to 40Hz or so where my sub will take over. Roughly how big a sealed enclosure does the XLS10 work well in, it's parameters suggest some unrealistic tiny box with a high f3 but obviously this isn't the case. In my planned enclosure I will have roughly 35L to play with, amplifier power and running a LT arn't a problem, whats the best way to get it flat to 40Hz in a sealed box?

Finally of the DST drivers you sell which is your favourite mid? The 12M4531G00 looks the best on paper but it has reasonably low power handling and is it really worth the cost

Thanks for the help 😎

 

[richie00boy]

If you're using the XLS10 down to 40Hz, you might as well do a vented cabinet if you have 35 litres to play with, and do away with your other sub altogether. Otherwise you will have too many crossovers in too small a band.

The XLS10 is designed to be used in a small vented/passive radiator box, that's why you get bad results when trying to use it sealed. You can overcome the frequency response problem somewhat with a Linkwitz Transform, but as you have a reasonable box size available you would be cutting your nose off to spite your face by not going vented/PR, as you would gain a lot more SPL.

 

[Cal Weldon]

I think rabbitz has hit the nail on the head. The CSS units try so hard to sound good as a WR or FR that choosing only a portion of that might not be the best bang for the buck. They are quiet but extremely well detailed and natural sounding.

 

[rabbitz]

Peerless does not recommend downfiring of the XLS drivers. You can work out if a driver is suitable by looking at these pages.

http://www.adireaudio.com/Files/TechPapers/DriverOrientation.pdf

http://www.partsexpress.com/resources/downfire.html

For info on the use of XLS drivers see the Tymphany application notes.

http://www.tymphany.com/resource_library_application_notes.html

IMO, I'd go vented but you have me puzzled as you say you are going to 40Hz and then hand over to the sub. AFAIK, you set the sub up for HT to do the LFE channel which is around 80-100Hz and then you can set the other speakers to small or a variation of.

If you do need a woofer in the 3-way to do to 40Hz, the XLS IMO is not the way to go and better off with a dedicated woofer and not a sub woofer as it will sound better as you go up in frequency.

Ah.... mids. Yes, I'd say the Scan Speak 12M4631 is probably the best mid but very expensive and the rest of the speaker has to have matching high level drivers or it's wasted. You're after high SPL's, so I don't think it would cope well. The Vifa P13 also makes a great mid but it too has the power handling problem unless used in an MTM or TMM. The Peerless HDS drivers work very well as mids and are robust in power handling.

I think you might have to go up to a bigger mid (a mid woofer) to get the power handling. Linkwitz has some info on mid driver tests.

Think long and hard as it could end in tears if you make wrong choices.

 

[FullThrottleRic]

Thanks for the links 🙂

The main reasons for my choices on driver layout is based on the type of enclosure I'd like to have a go at building and having plenty of cone area to keep things linear at higher levels. I don't want to go into 'blow your head off' territory but the ability to play at reference levels is a design point. I'd also like to keep it looking reasonably slim and I'd also like to have a go at curved sides. The idea was to keep the front baffle's width to around 20-22cm and have the sides profiled in a teardrop shape similar to the Wilson Benesch Arc so it lookes smaller than it really is. Rather than trying to mount the woofer on the curved side I thought the teardrop profile would be ideal to mount the driver on the bottom at it's widest point.

1- The tweeter is pretty much set as the SS9500 as I already have a pair and really like them.

2- I want a dedicated midrange unit/s (read:- small), MTM or not I'm not yet sure. From a HT perspective MTM's limited vertical off-axis output is a good thing, but I've read in a few places MTM's have a certain sound to them that people either love or hate. Having not had the drivers to build a similar MT and MTM pair of speakers I'm not sure if I'll like the 'MTM sound' or not? Another reason for keeping the lower frequencies away from the mid's is I seem to notice dopplar distortion quite easily, and reducing mid excursion will keep this to a minimum. Origonally I was going to build Lynn Olson's ME2 for the mid-tweeter arangement, but with the Vifa mid's being discontinued I'm a bit worried if I kill a driver in the future I won't be able to get a replacement.

3:- The lower mid drivers are limited to 6-7" units by the baffle width, and after reading Zaph's driver roundup he gives the Seas W18NX a good writeup especially in the range I want this driver to cover. I was thinking of using 2 again to keep excursion low and have plenty of headroom.
I could port them and get them down to 50Hz, or use a a pair of SS 18W/8531G00's in a sealed box and get down to 55Hz, but the SS's are so expensive it'd be cheaper for me to buy the 4 Seas W18's and a pair of XLS10's than it would to buy 4 SS 18W's (Porting the SS's isn't an option, an 80L box would just be too big for me).

I only suggested crossing to the sub at 40Hz as neither the Seas, SS or Peerless woofers go below this anyway and my Sub goes flat to 10Hz in my room. From experimenting with my current setup I've discovered I don't like the sub to run much avove 60Hz as it's fairly close to the seating position it's easy to hear where it is.
Would there be an issue running full range fronts (assuming for a second they get down to 20Hz) with the sub running upto 80Hz or whatever instead of crossing everything below a certain freqency to the sub? Wouldn't this give too much output in the area the front speakers and the sub overlap?


So the 2 main things I have to figure out now I suppose are what midrange driver/s and configuration to go for, and how to get from the 80Hz (sealed) cutoff of the Seas drivers down to the sub. I could go with a ported enclosure which would do it but I do seem to like low Q sealed alignments better for whatever reason, keeping it sealed would also keep cone movement sensible at lower frequencies better than ported too.

I don't have stacks of cash to spend on this so really I'd prefer to get it somewhere near right first time, once the basic configuration is sound tweaking costs nothing really but time 😉


Is it just me or arn't there many projects like this around? Most projects seem to be either small standmounts or large horns ect focusing on high efficiency to get to high output levels. I'm looking to build something more along the lines of the Linn Artikulat 350 but slimmer and a fair bit cheaper 😀

Thanks for the suggestions so far

 

[rabbitz]

I tend to prefer the sub doing the LFE and the other speakers set to small but am modifying the centre channel so it goes lower.

A cone in a sealed box will have a greater excursion than a vented driver until the vented driver unloads below Fb and then it goes nuts but have never experience the problem.

There's a speaker by Joe Rasmussen that might give you some ideas and what is appealing is that it uses the same driver for the mids and bass so tonally should be a ripper and not have any variations.

http://www.customanalogue.com/elsinore/elsinore_index.htm

Sealed in a small box doing F3=40Hz is a big ask and maybe the LT is your answer or overcoming your problem with vented.

Have fun as it sounds like an interesting challenge.

 

[FullThrottleRic]

There's some interesting idea's there, I'm enjoying reading through that 😀

A lot of what Joe says makes a lot of sense, the short horn on the tweeter is an interesting idea I'll have to have a play with sometime. Also the notes on power compression from the voice coils heating up is something I hadn't really thought about before, it makes a good case for multiple smaller drivers over a single larger one. I need to get some drivers bought and test boxes made, unfortunately I don't have the time or money right now to do so

I'm still undecided what to do for the bottom couple of octaves, but so far I'm pretty set on my drivers. SS9500 for the treble, MTM Seas M15CH-002's for upper mids and a pair of Seas W18NX-001's for lower mids. I'll be keeping the crossover between the upper mid's and tweeter passive but using active EQ for baffle step ect, all other crossovers/EQ will be done with active filters.

I'll need to build the amplifiers to go with the speakers too, the little 6 channel chipamp I'm using at the moment is a bit wimpy methinks. Rod Elliott's Project 101 seems to have a lot of kind words said about it, to be honest if it sounds as good as my dinky chipamp but with more power I'll be happy. Running 3 of the amps per channel whould go plenty loud enough (potentially 800+ watts per channel if I build the high power versions ) If I'm feeling really fancy I could build the amps directly into the speakers to keep the speaker leads as short as possible, I suspect though they won't be a one-man lift lol.

This will obviously be a long term project, but I'll get some pictures up when I've got something worth showing

 

[rabbitz]

Yep, you've got your hands full for a long, long time.

The P101 is a good honest amp and IMO is Rod's best (that I've built). Different in sound to a Chipamp as you would expect and there are lot of happy builders out there.