Locally available Mid-Bass drivers

[Timber_MG]

I am looking for something nice to team up to a Seas 27TDFC/TV and thought I'd ask here. I am currently investigating a couple of drivers (no, this is not the el cheapo project) and wanted to know what was available locally (I know of Seas and Morel)

Seas have a couple of very nice well behaved drivers in the Performance Range (ex Basic) and availability and service is decent.

The Morel Mid-Basses generally have resonances mid-band and have been getting less than stellar reviews from overseas publications. Their motors are also too weak in general.

Apparently Vifa is no longer being brought in by some guys in Cape Town. So what else is being brough in amongst the traditional hifi drive unit manufacturers?

M.

[Hennie]

Foglar Sound in Cape Town was/is the Scanspeak distributors. According to one of the attendees at the DIY fest they still have some stock left. They never distributed Vifa AFAIK. Sonor is still listed by Avsa as a Vifa agent.

[Timber_MG]

Oh, application is a stereo speaker for a living room with excellent vocal understandability and budget is only a mild concern (though I'd prefer not going too exotic if I can avoid it and prefer not to have to ship it). Cross around 1k6-1k7 for a 5-7" is planned.

[Hennie]

Another thought. If you are building for somebody why not consider the Seas Excell range. Scanspeaks are a bit expensive for what they offer nowadays and although the Excels are not cheap they are among my favourite drivers. I have worked with the previous generation which was very similar except for the basket. Taming that breakup takes some care but once you have done that you have a very transparent sounding u nit. Definitely a cut above the Performance Range aluminium drivers. I mean if u build then you save a bit on cost so why not go for a better driver?

[Timber_MG]

I will check them out. I have always been interrested in what the 18W/8531G would sound like.

[Timber_MG]

I should really learn to hit F5 before posting. Ians speaks did get rid of that hash almost completely so perhaps I should have another look and incorporate a more extensive notch.

[Timber_MG]

(Alex would have a good laugh seeing the amount of flack he's been getting of late about the Excells though but perhaps one could risk it with someone else being the recipient).

It is true though that the european driver manufacturers have to start innovating more with all the competition from drivers in the east (especialy wrt some of the ceramic-metal composite stuff coming out of there thesedays, no wonder DST was in such trouble, even some the cheap stuff is using square CCAW coils thesedays).

Edit: double post

[Hennie]

Those drivers you are referring to are actually ceramic with a metal matrix. Not available for DIY though IIRC.

I don't think that Foglar has any 18W/8531G because they had mostly older generation drivers. In any case I would not select the 18W/8531G over an Excel because the Excel beats it in all respects except XMAX. Enery storage, distortion etc are all better for the Excel so I would just go for that, especially if good voice intelligibility is a requirement.

Compensating the breakup peak has more to it than meets the eye. What most guys do is just take a measurement and design a suck-out filter to match. But the problem is that in real life the driver works under large signal conditions, whereas the measurement represent smal signal conditions. When you get that right the driver sounds very transparent, and if you just get it almost right, there is a bit of hardness an splashiness to it.

But if you are interested e-mail me and I will send you notes and graphs of what I did. It is not in a format suitable for posting here ATM.

[Timber_MG]

Perhaps you should visit me next weekend after the listening session and we can discuss this further. Your 19mm Seas replacements are still here anyways.

[AlexD]

Martin
When can I get your order? :mrgreen: lol.The cone resonance will always be an issue as you know.(maybe I should start a rumour, New Excel mag cones with no breakup,lol)
@Hennie
I believe you have some good software for calculating or sim-ing crossovers.What would the effect be ,in terms of phase,on an Excel if one has to use 2 notch around the break-up point.My thinking is with the change in temp of the crossover components,if one could still catch the break up with these notches.I suppose measurements will ultimately tell the story,I'm working towards a measurement setup so for the moment,sims are all that are available to me
Cheers

[Timber_MG]

I'll see what my options are first. I didn't actually quite budget for an Excell as at SA prices (hennie, tsk tsk tsk)

It's not the what, it's the how. Your software should allow you to model what a second notch does under small signal conditions. It affects both integration as well as other factors (I could have just inverted the polarity on Ian's tweeter for example and it would have measured the same but it still doesn't mean it would've been properly integrated).

If you go too far your group delay can go very high in the area where the ear is most sensitive so you have to be very careful about how you go about placing it. If it is modulated under large signal conditions the distortion is strongly non-linear and this is more audible than THD, IMD and any other conventional distortion measures. Caveat emptor.

There is a reason why the Excells are the most difficult drivers in the world to get to play ball and why it is recommended most inexperienced designers steer away from them, especially when done passively. I would certainly invest in a measurement system capable of doing measurements like Linkwitz with shaped bursts as a normal measurement system will barely show up these effects. Classical case of most measurements not being able to correlate with what one hears. If you just use a measurement system to optimize your crossover network in some generic way your end result will still be a good bit sub-optimal (meaning with the law of diminishing returns more handily outperformed by for instance a more cost-effective but properly implementd solution)

[Timber_MG]

Yes hennie, breakup at 14kHz on the 4" but better damped than anything I have yet seen. The "pure" ceramics like the visaton et al don't have a chance from what i've seen but I have no intention of filling a 1000+ unit order in the east and have the triads pitch up to ensure payment.

[Hennie]

Timber why don't you just head over to Alex's place and pick up a nice pair of Excels....

Metal matrix ceramic drivers are not a realistic option for now. As we have seen sourcing is problematic and they have not yet been released officially.

The Scan slit paper cone driver does give you an easier crossover at the expense of higher in band distortion and energy storage. The Excels have more out of band artifacts that you have to tame.....so pick your poison. I prefer the out of band stuff to the in band stuff anytime.....

I have not worked with those specific Scans but have heard them in commercial speakers. While they are quite nice, they don't really offer the level of transparency that the Excels offer, which IMHO approach the transparency of electrostatics.

That and the price of the Scans.

If the Excels are beyond your budget the Alu cone Seas drivers are competent performers.

I have a feeling Foster / Foster Culver maybe into metal matrix ceramic cones too but as you know they will only play OEM to the big co's.

@Alex, I believe the key to success with the Excel cones are a bit lower XO than D'Appolito did, retain a high cut-off rate and do overcompensation for the breakup peak. But the standard D'Appolito crossover designs do reasonably well and are nothing to be ashamed of.

[Timber_MG]

Eish hennie, with friends like that you don't need bank managers. And Alex delivers the cheap wares too... I'll considder it but for close to the money of a DAS 10B ... i dunno.

Do you recon Alex will be doing a 1khz modified cauer elyptical crossover next with a 8th order hybrid series topology to make it with less than 20 components?

Well, with a Samarium Cobalt magnet motor, it makes Audio Technology look reasonably priced. Next you'll hanker on about a phenolic HPL pultruded under abnormal pressures speaker cab like a friggin rocket nozzle. Lemme do the cheapies first and then perhaps do a moulded midrange (not to mention the monsters too)

Foster do that 800cm Back to the Future effort, but I don't even want to smell what a true blue Japanese OEM goes for if it's not another 4" Fostex re-run. Why not ask them to do an Alnico magnet, seeing that it is going so cheaply thesedays that even TAD is hard pressed to continue production.

[Anonymous]

Did you ever get hold of the RCF stockist? Paulo Cacci, he said he could get any of them...

http://www.rcf.it/VediMacro.phtml?IDMacro=2730&m1=1&m2=1&m3=1_1_9

http://www.rcf.it/VediMacro.phtml?IDMacro=1638&m1=1&m2=0&m3=1_0_13

Maybe if you are really feeling funky...

http://www.rcf.it/VediMacro.phtml?IDMacro=2722&m1=0&m2=0&m3=0_0_1

Can't see South Africa there... anymore