Horns: Klipsch vs. Altec vs. JBL vs. ???

[merlin]

The 1500 FE is the standard driver in the 4338 that I enjoy. The 1500 AL is the unit used in the 9800k2. The measurements are more or less identical.

The impedence curve is the same, the sensitivity within sample variation, so a swap will be interesting to see if the Alnico magnet drivers are really worth £1K each.

On the test measurements I have seen, the AL exhibits noticably lower distortion - whether this is a good thing time will tell, but when using them for subs, the drivers were quite unique in their ability to reveal subtle detail in the bottom half.

 

[murray johnson]

It will be interesting to hear how you get on. That's an expensive upgrade although I don't doubt you'll be able to sell whichever drivers are left quite easily. Whereabouts does the xover happen on those? 600 Hz ish? I imagine if there is a significant difference it would be more at the upper end of what that driver is doing. I expect it will be quite noticeable.

rgs

Murray

 

[joel]

Whereabouts does the xover happen on those? 600 Hz ish? I imagine if there is a significant difference it would be more at the upper end of what that driver is doing. I expect it will be quite noticeable.

It's actually around 900Hz. Interestingly, that xover point is possibly the speaker's weak point, as there is a noticable dip. If the the Alnico drivers can go someway to fixing that...

 

[merlin]

Murray,

I have the 1500 al's lying around anyway so I might as well have a play.

 

[joel]

You can see the comparative measurements here.

Is that part of "project May"? Unfortunately, I cannot access this page as I am unworthy...

 

[murray johnson]

Blimey, 900 Hz is quite high for a 15" (even direct radiating) to be going without becoming too obvious. It must be some unit. Do you know what sort of xover they have in there?

 

[joel]

I think Merlin's JBLs cross a little lower in fact, around 850Hz. My Evs (with a titchy 12" driver) cross at 900Hz, which actually works better than the JBL (JBL's 12" offering, the 4428, was too atrocious to mentionin this respect). Pioneer also cross at around the same area for the exclusive speakers, although Kinoshita crosses the same drivers at around 400Hz...
I'm not clever enough to say what kind of xover is used in each speaker, but I'd guess something very steep for the JBLs and much less so for the EVs. Probably entirely wrong, as usual.

 

[joel]

I'm thinking of trying the JBL 2405 with my speakers. How do I tell the Alnico version from the ferrite one?

Where and how are you thinking of doing the crossover?

 

[Romy The Cat]

Hello Romy,
The end point is *exactly* I'm thinking about, and this is why I have not formed an opinion on these units before actually hearing them.
There are specific things the HF has to do in my system, but I need to discover which drivers come closest. Published specs and forum opinions are not good enough for basing a decision on - although they can be useful pointers (especially the specs - or lack of them).
Also, I have at best only very average hearing. Stuff lots of sudiophiles apparently hear passes me by completely. I guess I'm fairly easy to please in that sense.

Joel, as I understand you are in Japan, so I would like to inform you that your folks came up with something that “might” be interesting

http://www.goodsoundclub.com/Forums/ShowPost.aspx?PageIndex=2&postID=2789#2789

I did not hear them and I do not know if they are correct. If you have chance to hear them then please share your findings, preferably in direct email as I do not go to this site.

Rgs,
Romy the Cat

 

[merlin]

I'm thinking of trying the JBL 2405 with my speakers.

Hi Markus,

just thought I'd mention that GT seems to think that passive networks really kill the 2405 and recommends an active high pass with a chip amp.

 

[Markus S]

Yes, I can see how that would make for a nice, uncomplicated system.

Seriously, how is that supposed to work? An active high-pass between pre and power, and then a power amp into the passive XO between mid and bass drivers? Or does the high pass take its signal after the passive XO?

 

[merlin]

Markus, here's what Greg actually says. I guess you would just send a ful range signal from your pre to an active high pass.

The ring radiator hates passive networks. A major improvement in the upper range would be to drive the 2405 from its own little amp. You only need 3 or 4 v rms. The 2405 does 110 dB for 2.83v. It is padded way down in the system. There is little real power at those frequencies anyway. You only need to know the voltage output of the amp, power is irrelevant. The 2405 is about 12 ohms and won't draw much current. I would use some little chip amp with a 2ond or 3rd order low level highpass in front of it. Take off the passive network to the ring and just feed it straight. Make sure the amp doesn't make a DC thump on turn on or turn off. That will fatigue the diaphragm. The amp will also have to have really low noise characteristics as any hiss will be really loud directly into the ring.

 

[joel]

I'm particularly thick tonight; I still don't get GT's suggestion. At least not in this context.

 

[Markus S]

It comes down to semi-active bi-amping, if that exists. You need a system where you can split the output after the pre. The full range signal goes into one power amp which drives the mid and woofer passively, i.e. with a x-over between amp and drivers .

For the treble leg, you do the high pass (that crossover is really just a cap or two and an inductor, so it's not actually an active crossover in the accepted sense of the word) in front of the chip amp - Greg himself was using an ancient Marantz transistor amp, I think - and drive the ring radiator direct from the chip amp, i.e. actively.

It's an odd arrangement that has potential. However, to make it work, I think you'd need a lot of experience and possibly some testing equipment that I do not have.

If I do get the 2405, I think I'll do a passive x-over and spend a bit of money on some good parts.

 

[bottleneck]

let us know if you get them Markus.

I continue to like mine a lot.

 

[Markus S]

Hearing them at your place was the inspiration, of course. I'll be off on holidays soon and am currently working a lot to get rid of my backlog before I leave. After the holidays, I already know I'll have a few more weeks with a lot of work. Then Xmas is looming.

Realistically, it might be the new year before I get down to anything serious. In the meantime, if anyone happens to spot a nice pair of 2405s at a good price, please alert me as I won't have the time to scan any sites for that.

 

[bottleneck]

ok, will keep my eyes peeled.

i got mine from e-bay. You also see studio's selling them sometimes, which is nice when they measure/test them before flogging...

 

[scolarest]

Now lets stop buggering about, these are the babies
http://cgi.ebay.de/2-Stueck-Klangfi...7QQihZ009QQcategoryZ22062QQrdZ1QQcmdZViewItem

M

 

[joel]

Now lets stop buggering about, these are the babies
http://cgi.ebay.de/2-Stueck-Klangfi...7QQihZ009QQcategoryZ22062QQrdZ1QQcmdZViewItem

They are indeed. One of the best two or three speakers I've ever heard. Spookily real. Hideously expensive in Japan, too. So I'd expect them to come here or Korea or maybe Taiwan.

 

[merlin]

Blimey, 900 Hz is quite high for a 15" (even direct radiating) to be going without becoming too obvious. It must be some unit. Do you know what sort of xover they have in there?

Murray,

Just to let you know that the alnico magneted 1500al is subjectively just far more subtle and refined on first listen. You are right - the main difference is in the upper bass lower mid.

A worthwhile experiment. I am desperately hoping to use these alnico drive units in an exciting two way project that depends on the availability of some rather special drive units.

A trip to Definitive today though rather redefined expectations - listening to Kevin's four way " work in progress".