Mid range driver advice needed

[mafuta]

I use a quad amplified 4 way horn system.It utilises a Jbl 2490 to cover 180Hz -900Hz ,Goto SG370 for 900Hz-6kHz and a Goto tweeter.

Problem is that I have become increasingly frustrated with the idiosyncrasies of the Goto mid driver and want to replace it with something less fragile.I have had an Iwata horn with a 1.5 inch throat built for the new driver.Initial plans were for a TAD 4003.However these are virtually unobtainable now and soundwise totally unknown to me . I recently pulled my JBL 2440s from storage and installed them in place of the Goto.I found them somewhat coarse above 3kHz,somewhat smeared and lacking in detail.As an interim measure I replaced the 2440 dias with 2450 SL dias and was totally bowled over by the detail retrieval and smoothness of the sound.

I am now looking for a new driver to use with the 1.5 inch horns.I really wanted to get the JBL 476 Be but all attempts by my local Pro dealer have been unsuccessful.All I could get from the Consumer distributors was a very curt "No".Even showing them Mr Timbers' post on this forum helped nothing.

It seems that my options now would be the TAD 4003,JBL 2452 or 2435. I am very nervous of a too edgy and bright sound.As my Goto drivers are quite a bit more expensive than any of the above,I am not too worried about the cost differential between them.

I have read all the posts about these drivers on this forum,but need advice for this particular situation, i.e. specifically a smooth,but focused and detailed sound delivery from 900Hz-6kHz with no need for equalisation or other electronic smoothing.As I use a tweeter I am not too concerned about HF extension above 10k.Can anyone help?Of course if someone could point me to the elusive 476 Be they will have my eternal gratitude!

http://img176.imageshack.us/img176/8728/a129yv8.jpg

.

[Robh3606]

detailed sound delivery from 900Hz-6kHz with no need for equalisation or other electronic smoothing. As I use a tweeter I am not too concerned about HF extension above 10k.

Have you tried ordering 435Be's?? You may be able to get a pair of them. You can certainly get 2452Sl's from JBL Pro. The only time I have ever heard the TAD's I didn't like them but I will chalk that up to the system they were in and not the drivers. If you can afford any of them just experiment. You are not going to know what you like until you hear it yourself.

Nice set-up any more pictures you can put up??

Rob:)

[subwoof]

900hz for the 1.5 driver clearly is on the LF limit of use for the 3" diameter 2435's so I suggest the 4" coil 2452SL ( or the earlier 2450SL with the coated dia ).

Both will give you the warmth and clarity that the 2440 had with the added benefit of a newer phase plug design. Putting the coated Ti dia into the 2450 body would also work well and would be the equivalent of the 475 used in the K2

BTW How did you mount the 2" exit on your 1.5" horns?? that would of required a backwards adapter that would "bias" the comparison....

sub

[mafuta]

How did you mount the 2" exit on your 1.5" horns?? that would of required a backwards adapter that would "bias" the comparison....

Thank you for the advice .The Current horn that the 2440s(and Gotos via a special Goto-built foot long adaptor) are mounted are 2".The new 1.5 inch horns(not shown) were built for the TAD or 476 Be (which I thought I could pop in to order)-until the Frankenstein 2440 threw a spanner in the works.Also playing a role in the decision is the fact that the 2490 used lower down was initially planned as a stopgap (until doubled Gotos could be afforded) but has turned out to be the star of the system.



Have you tried ordering 435Be's


I am afraid the response would be the same.My Pro dealer actually tried to source the 476 from the Consumer distributor.They told him they only sold complete systems and not parts.Pity,the 435Be would be a nice choice as I could easily get different crossover boards and the 2490 can be run a few Hz higher.

Are 435Be available separately anywhere in the world?

[Mr. Widget]

Are 435Be available separately anywhere in the world?Yes. They are readily available in Japan. I don't think the JBL Dealer was being rude. I really doubt he could get the 476Bes. Even JBL employees would have a hell of a time getting them. They are made exclusively for the Everest system and I believe they are still struggling to keep up with demand.

The TAD TD-4003s are still available, but the last time I checked they were back ordered until December. You might find a dealer in Japan or Europe who has some in stock.

Having heard and measured all three drivers, I'd say that the 476Be and the TAD TD-4003 are quite comprable and the 435Be being very good but not quite at their level.

Another driver you could consider is the ALE A7550. It is slightly smaller at 34mm, but a friend who has used both the TD-4003 and the ALE A7550, liked the ALE slightly better. It is significantly more costly though. I believe you would have to source it from Japan as well.

Beautiful system!


Widget

[speakerdave]

The geographical distance could be a problem, but perhaps this is a job for Steve Schell's Cogent True-to-Life field coil/phenolic drivers, if some kind of demonstration could be arranged. I have not heard them myself; I am most likely not in the target demographic. You could PM him here for information. There is also some contact information on line:

http://cgim.audiogon.com/cgi-bin/manu.pl?cogenttruetolif&1&showmanu&C&&&

David

[mafuta]

Mr Widget

Thank you for a most helpful post.The ALE are very closely related to the Gotos I own.Could you please comment on the sound of the TAD?As I said I am very afraid of a cold, steely bright sound.If the TAD is close to the ALE and the ALE close to the Goto I suppose the decision is simple-but that is a lot of ifs and the more elusive the 476Be the more desirable it becomes!

SpeakerDave.

I am afraid at $14 000 per pair the Cogents,tempting as they are,are just a little too pricey for me(I am more comfortable around the $7K mark).They are within a whisker of the most expensive ALE and more than the most expensive Goto.I am sure they are worth every cent though!

Sender of private mail

Thank you for the post.I shall definitely follow it up (with both thumbs firmly held).

[Mr. Widget]

Could you please comment on the sound of the TAD?As I said I am very afraid of a cold, steely bright sound.A friend of mine and I went over to a buddy's house this morning to spend a couple of hours comparing preamps. We were comparing the BAT REX and the Audio Research Ref2. A couple of weeks ago we had a shoot out between the Audio Research Ref2 and Ref3. The Ref2 won.

In any event we were using the system pictured below that uses the TAD TD-4003 and the TAD TH-4003 horn. While the BAT REX was more revealing it was also less "warm" sounding than the Audio Research, but it never sounded cold, steely or bright. We even turned up some large orchestral works to concert levels and the sound was huge, effortless, and in the words of my planar speaker loving friend, "amazingly uncolored and not the least bit horn like." "If you didn't see the horn, you'd never believe we were listening to a horn loudspeaker."

FWIW: Both line stages sounded fantastic. Two of us preferred the Balanced Audio Technology REX and one the Audio Research.


Widget
.

[vernb]

Try Matsj. He has the 435be drivers for sale right now at a very reasonable price. you can find them at www.hifimagasinet.com (http://www.hifimagasinet.com) and do a search for jbl. He has them listed under K2 S9800 as far as I remember.
Yours
Vernb

[mafuta]

Mr Widget:

Thank you again.In the absence of the 476Be,I'll fall in line for the TADs-Even though I'll hear them for the first time when I open the box.

What makes it even worse is that I just saw the post (by 4313B) with the freq resp of the 476. Above 900Hz -10k it is a virtual carbon copy of the 2440/2450SL hybrid on the Iwata horn that I measured in my lounge this afternoon(including the little 3db bump at 1k!) Of course it doesn't mean they sound the same,but I would have known what to expect.

P.S. Ironic that I have been shopping for line stages and that those 2 were the front runners ! But as they both do better when run as balanced I have since commisioned a custom built from a local manufacturer(www.valveaudio.co.za (http://www.valveaudio.co.za))

VernB:

My Danish? is totally MIA, but it seems to be 2435s he has.It now seems to me that for home use Aquaplassed dias are essential.But thank you.

[dino]

mafuta your design and set up :jawdrop::eek::applaud::applaud::applaud::applaud: fabulous! just looking at it gave me a HARD on

[mafuta]

Nice set-up any more pictures you can put up??



http://img301.imageshack.us/img301/9170/sitkamer009jpg9dm.jpg




http://img501.imageshack.us/img501/4219/eqpjpgue9.jpg


http://img447.imageshack.us/img447/5890/iwatainvolvojpg3jb.jpg


http://img210.imageshack.us/img210/8458/bouaanhuisaug2005099rs8.jpg


http://img79.imageshack.us/img79/5782/sitkamer0017dg.jpg

[andywin]

Nice system.....

What drivers do you in the bass horn and how do you deal with the time alignment?

Also is that a Machine hat chamfers the edges of CD's in one of your pics? If so, how much difference does it make.

[stephane RAME]

http://pagesperso-orange.fr/francois.mastroiannidiy/M%20Rogerro.htm

:applaud::applaud::applaud:

[mafuta]

Yes indeed Monsieur Rame.

I do not believe I ever claimed originality.I wrote this on Audio Asylum some years ago:



Thank you for your kind comments,

I am well aware of your beautiful system.I wonder how many times I have read that inspirational article on the Belgian Audiophile School site.Particularly the 3 dimensional curves of your basshorns is to he much admired although myself,the architect, structural engineer and builder involved all shied away from such awesome complexity and opted for a much simpler shape with only a 5 degree slope in the roof of the horn.
Still yours must be the ultimate expression of what can be done.In the end we achieved a 0,5 cm tolerance in the basshorn but it took some really fine plastering.How you achieved that with naked brick is mind boggling.
Your work as well as that of M Rogerro has served as inspiration in creating this and although I have never met or corresponded with either I salute you and Monsieur Rogerrro for your willingness to publish and so share your secrets .Also people like Karel Schees (Carolus here) who freely shared their experience and expertise.The horn world is small and the mega-horn world miniscule.The fact that much of it is locked away behind the barriers created by Japanese script and language (Thank goodness for Jean Hiraga) and to a lesser extent French makes navigating these waters all the more challenging With gratitude

[Mr. Widget]

This picture really puts it into perspective!


Widget
.

[richluvsound]

Widget ,

that looks like a tad profile . Cast me two of them ,will you :applaud:

Rich

[mafuta]

What drivers do you in the bass horn


5 Altec 515-16g per channel.The aim here was fast midbass rather than sheer extension.The system is flat to 23HZ ,3db down by 21Hz and more than 10 down by 19 Hz.Probably more due to horn cut-off rather than drivers



how do you deal with the time alignment


I assume you mean in the bass.Short answer is I don't.The crossover there is 24db/oct at 180 Hz.The 6ms delay here is not audible to either myself or any of my fellow testers.I personally can hear a 8-9 ms delay at that f but not shorter.Conversely,higher up the other horns are aligned to within a mm as it is painfully obvious at higher fs



Also is that a Machine hat chamfers the edges of CD's in one of your pics


No .

[speakerdave]

. . . . higher up the other horns are aligned to within a mm as it is painfully obvious at higher fs . . . .

mm really? or ms?

David

[mafuta]

http://img530.imageshack.us/img530/1693/driversjpg1jg7.jpg


Thanks to all of those who gave advice and those anonymous members who supplied more than advice.

The final assembly of drivers are JBL 2440. JBL 2440 with 2450 dia,TAD 4003,Goto SG370 and JBL 2435(aquaplassed).So far the 2435 has been the firm favourite but the TADs arrived today and I may have a new permanent resident in the system

[JeffW]

http://pagesperso-orange.fr/francois.mastroiannidiy/M%20Rogerro.htm

:applaud::applaud::applaud:

I don't have any of the other gear, but I have many of those same vacuum tubes :D

[PerthPete]

Hi. My name is Peter. I am in Perth in Western Australia. I have long been interested in large bass horn systems. My current system is a large electrostatic based system. - Soundlab.

Would you be willing to share some information about your amazing bass system?
I have seen the site for Marcel Roggero but cannot work out how to contact him.

I intend to build a large dedicated listening room and would consider building bass horns similar to yours or some other design.

Any help gratefully appreciated.
Peter

[Hoerninger]

http://www.audioheritage.org/vbulletin/showthread.php?11909-Paragon-XXL&p=249122&viewfull=1#post249122

[Odd]

Or have a look here;
http://www.royaldevice.com/customita1.htm

[mafuta]

Hi. My name is Peter. I am in Perth in Western Australia. I have long been interested in large bass horn systems. My current system is a large electrostatic based system. - Soundlab.

Would you be willing to share some information about your amazing bass system?
I have seen the site for Marcel Roggero but cannot work out how to contact him.

I intend to build a large dedicated listening room and would consider building bass horns similar to yours or some other design.

Any help gratefully appreciated.
Peter

This is my second attempt at a response as the first disappeared on completion.
Basically such a bass horn can only be designed for you by yourself using your own philosophies and preferences. As the perfect horn will have infinite length and size, every horn design has to be a compromise. Only you can decide where and how you are going to compromise.

I can however tell you what I have done: In building a horn you have to decide on length size of mouth and throat, flare and cut-off. This is the total opposite sequence that one would use in say a midrange horn.

Length: 3 Issues here: Firstly, available length. Secondly phase issues. If one is willing to use digital delay this is not an issue. In my system however I use mainly Mark Levinson and Studer A80 analogue recorders as well as a Thorens Reference turntable. I am simply not willing to digitise their output for signal manipulation. I therefore cannot have too long a horn. I spent months with an experimental set-up do decide what is acceptable to me. I finally concluded that I can hear a difference at 2.8 meter between bass and mid drivers at the 225Hz crossover. As the midbass and midhorns have their drivers some 700mm into the bass horn I decided on a depth of 3m. Taking the available mouth space and size of throat I came down on a21Hz horn. The third issue is how long must a horn be to function as a true horn at a certain frequency. Again this must be juggled against 1 and 2.From my measurement I am happy that this one functions as a true horn into the low to mid 20s
Throat: I decided against the use of a front chamber so have a driver to throat surface of 1:1. As the roof of the horn slopes at a 6 degree angle towards the back (to avoid standing waves) I could accommodate 5 15 inch drivers.
Flare. Before embarking on this I built several very large horns from wood. The Tractrix horn performed very poorly in the bass so I decided on a Hyperbolic- Exponential horn with a flare coefficient of 0.707. This mainly to accommodate all the above parameters.
All of the above could only work if the horn was a 21Hz design. Please bear in mind that the horn has to be designed around the chosen drivers. In my case I used Altec 515 16Gs. They do not go as deep as other drivers but I feel can be used higher and has an appropriate efficiency. I have no proof for this but I always felt a speaker system would “track” input better if all parts have similar sensitivity I was aiming for 110db/W here. I believe M Rogerro used 515Bs in his system.
Rear loading: In order to extend the horn as low as possible I used reactance annulling, giving a rather small sealed chamber behind the drivers. I believe Monsieur Rogerro use a more complex tapering tunnel set up that finally exists to outside.
Was this done correctly? I don’t know. Should I have done it differently? Again I do not know. It is now almost 7 years since it was completed so Baranek’s law have had ample time to reverse but I am still happy. The tweeters have changed 3 times, 5 different mid drivers and 2 midhorns have been used but not a single thing in either bass or midbass transducers or horns.

[Lee in Montreal]

Currently running knock-offs of JBL 4520 (twin 15" per cabinet) and currently designing an improved version that goes lower (27Hz) with a longer path, bigger mouth and twin 18".

As was previously mentionned, a bass horn is all about compromise. Mostly size compromise. If you are willing to go up to a 5 or 6ft tall cabinet, then you can get some positively surprising results. ;)

[Eaulive]

Currently running knock-offs of JBL 4520 (twin 15" per cabinet) and currently designing an improved version that goes lower (27Hz) with a longer path, bigger mouth and twin 18".

As was previously mentionned, a bass horn is all about compromise. Mostly size compromise. If you are willing to go up to a 5 or 6ft tall cabinet, then you can get some positively surprising results. ;)

So Lee, did you learn to like them? it's been more than a month, give me a report. Mine are ready yet.