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01-03-2011

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	26
Post ID:	15363
Reply to:	15362

Some thoughts about the audiofilofine tweeter.

audiofilofine wrote:
All parts of the tweeter shave been designed and built.All are built in magnetic steel in preferenceto pure iron because pure iron is heated during processing and after processing was not possible to check that the characteristics of the metal were the same as before processing.
Solenoidsto180voltssaturatethe core.

Diaphragm shave been modified by eliminating the resonance.
We tried two types of diaphragms and two types of horns with spinnerPFC.
With the horns of the first photo, the answeris within 1 db from 6000 to 23500 hz spl 110 d b 2.83V1 m,with the second type of horn is within1.5dB from 4000 to 19500Hz with an SPL of 114 db 2.83V1m

http://audiofilofinehighendproduct.blogspot.com/2011/01/tweeter-horn.html

audiofilofine,

I have a few comments and questions.

First about the posting. I guess you are from Italy and your use some kind of text editors that user a lot styles that are not renders properly a browser with western meetings. I just would like to let you know that my posting window has a tool that will fix all formatting problems. In the right corner or “reply” interface you will see a blue “W” button that says “Clean All MS Word formatting”. It is very helpful. Also the buttons on the extreme left “Preview Window” would allow you to preview your post before submitting it.

Now about your tweeter. If it is not some kind of trade secret then what diaphragm you used, how did you dealt with alleged resonances and the most important how methodologically you concluded that the problems that you reportedly had were resonance-related?
Another thing, you chose to close the return magnetic system with a solid cylinder that prevents hit dissipation from electromagnet. Do you driver get too hot? Can you report it’s temperature after 3-4 hour of operation?

Now, some more important thing. It is a pure speculative guess on my part but I would say that considering the type of the horn you use and the sensitivity numbers that you provided I can estimated that you do not saturate your gap hard enough: ether you run too little current or your use too low permeability of core. You see, this type of the horn (absolutely ridicules for a tweeter in my view) shall heave you over 10dB equalization gain. With 100% of driver efficiency and no horn EQ the sensitivity would be 111dB (1W converted at 100% to sound pressure).So, with this type of the horn and proper high saturation (for tweeter only) you shall have 118dB or even more. You might have problems to drive more current with this air-restricted electromagnet. Take a look how Cogent did their drivers – they did cooling in a very right way.

Rgs, Romy the Cat

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

01-03-2011

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audiofilofine
Posts 29
Joined on 02-26-2010

Post #:	27
Post ID:	15364
Reply to:	15363

Tweeter reply

Romy the Cat wrote:

I have a few comments and questions.

First about the posting. I guess you are from Italy and your use some kind of text editors that user a lot styles that are not renders properly a browser with western meetings. I just would like to let you know that my posting window has a tool that will fix all formatting problems. In the right corner or “reply” interface you will see a blue “W” button that says “Clean All MS Word formatting”. It is very helpful. Also the buttons on the extreme left “Preview Window” would allow you to preview your post before submitting it.

Yes Italy
OK

Now about your tweeter. If it is not some kind of trade secret then what diaphragm you used, how did you dealt with alleged resonances and the most important how methodologically you concluded that the problems that you reportedly had were resonance-related?
Another thing, you chose to close the return magnetic system with a solid cylinder that prevents hit dissipation from electromagnet. Do you driver get too hot? Can you report it’s temperature after 3-4 hour of operation?

Sorry but I prefer not to say the brand of the diaphragms .
I used only moving parts and not the structure, the suspensions were treated with a silicone resin

The metal structure at the beginning was open but the magnetic circuit was not working well,the magnetic force of the solenoid was lost,I arrived at the solution completely closed after several prototypes.

http://audiofilofinehighendproduct.blogspot.com/search?updated-max=2010-11-08T12%3A59%3A00%2B01%3A00&max-results=7

Half an hour aftert he meta lreaches a temperature about 46 to 50 degrees(depending on ambient temperature) and the temperature remains constant, even leaving under tension.
The metal trumpet acts a sheat sink

Sorry but i dont say
Now, some more important thing. It is a pure speculative guess on my part but I would say that considering the type of the horn you use and the sensitivity numbers that you provided I can estimated that you do not saturate your gap hard enough: ether you run too little current or your use too low permeability of core. You see, this type of the horn (absolutely ridicules for a tweeter in my view) shall heave you over 10dB equalization gain. With 100% of driver efficiency and no horn EQ the sensitivity would be 111dB (1W converted at 100% to sound pressure).So, with this type of the horn and proper high saturation (for tweeter only) you shall have 118dB or even more. You might have problems to drive more current with this air-restricted electromagnet. Take a look how Cogent did their drivers – they did cooling in a very right way.

Rgs, Romy the Cat

In my opinion,the magnetic circuit of Cogent is not closed properly but I could be wrong because I saw them only in photos
The black horns used with phenolic diaphragms and not look up very high but the highest spl.

Measurements were made with a simple PC and a microphone Beheringer.
Solenoids bear up to 200 volts without problems, but with increasing voltage increases the spl but the responseis less linear with a 3 db boost of around 12,000hz
Tweeters area workin progress and no thing is final
I have yet tounder stand why changing the valve of power supply sound changes a bit even though the same voltage

01-03-2011

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	28
Post ID:	15366
Reply to:	15364

The Italian tweeter.

audiofilofine wrote:
Sorry but I prefer not to say the brand of the diaphragms .
I used only moving parts and not the structure, the suspensions were treated with a silicone resin

Yes, it is good thing to treat suspensions not the cone. The silicone resin, the old type of table tennis glue and the JBL Aquaplass are fine to do the job but the all easy a bit transients. They find on MF driver but I do not know if I would like to use them on tweeters. Still, what make you to feel that it was the resonances? Was it something auditable that you did not like?

audiofilofine wrote:
The metal structure at the beginning was open but the magnetic circuit was not working well,the magnetic force of the solenoid was lost,I arrived at the solution completely closed after several prototypes.

http://audiofilofinehighendproduct.blogspot.com/search?updated-max=2010-11-08T12%3A59%3A00%2B01%3A00&max-results=7

I see, the external panel is complimentary to the 4 rods the forms the magnetic back path. You feel that the rods are not enough. Did you model the magnetic systems of you just arrived to it this concussion by listening experiments? I am sure that you know that warring the permeability of your rods you might change the sound….

audiofilofine wrote:
In my opinion,the magnetic circuit of Cogent is not closed properly but I could be wrong because I saw them only in photos The black horns used with phenolic diaphragms and not look up very high but the highest spl.

Possible, I cannot judge on it. From the cooling perspective however the Cogent drivers are perfect in my few.

audiofilofine wrote:
Half an hour aftert he meta lreaches a temperature about 46 to 50 degrees (depending on ambient temperature) and the temperature remains constant, even leaving under tension. The metal trumpet acts a sheat sink

Yes, I understand that metal trumpet acts a heat sink but do not forget that between the metal trumpet and electromagnet you have a diagram. So, of your heat sink is at 50 degrees then the diagram is at 60 degrees. It might be not the end of the world but you need to do all sonic tastings with the well warmed diagram operating at it’s cruse temperature.

audiofilofine wrote:
Solenoids bear up to 200 volts without problems, but with increasing voltage increases the spl but the responseis less linear with a 3 db boost of around 12,000hz

This is what you are approaching to the saturation point.

audiofilofine wrote:
Tweeters area workin progress and no thing is final
I have yet tounder stand why changing the valve of power supply sound changes a bit even though the same voltage

Sure, I understand. Are you planning to convert it into some kind of commercial product?

One more thing, at your blog you reported that retard Angelo from Brazil as your friend. It is totally up to you how you are willing to compromise your standing but be advised that in my books the people befriended with that that Brazil idiot does not deserve my attention. That guy is ultimate nightmare, so pathetic and so primitive that it does not deserve my criticism. I know that by saying it again publicly I again will receive in no more that I hour a bombardment of emails from that idiot insisting that I need to embrace Christianity, to love Angelo and do not deny him my attention. Well, if Christ out there then I wish him to expire that piece of shit from Brazil. Now, he is your friend, deal with it.

Rgs, Romy teh Cat

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

01-16-2011

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audiofilofine
Posts 29
Joined on 02-26-2010

Post #:	29
Post ID:	15427
Reply to:	15366

Field coil tweeter

After several tests of listening and somehow I felt that the best solution is fully closed.
The heat is part of the project and not to damage the diaphragm, also the hot air is compressed better than cold and thus distorts less.
Even leaving the container open the diaphragm would have been nearly the same temperature.
The drivers I build them for me and so far I have never sold any.

01-16-2011

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	30
Post ID:	15428
Reply to:	15427

Enclosed vs. opon?

audiofilofine wrote:
After several tests of listening and somehow I felt that the best solution is fully closed.
The heat is part of the project and not to damage the diaphragm, also the hot air is compressed better than cold and thus distorts less.
Even leaving the container open the diaphragm would have been nearly the same temperature.
The drivers I build them for me and so far I have never sold any.

Audiofilofine, if you feel that enclosed driver produced better sonic result then can you describe what sonic difference is between your tweeters with open frame vs. your tweeter with enclosed frame? Also, when you close the tweeter frame then you use just sometime outer surface of you plug the outer surface into magnetic system? If the later, one then what material you use for your magnetic return path?

For all intended purpose if your do not use the outer enclosure in magnetic return path then outer enclosure shall not have any difference. So, I would like to know what specific difference you hear.

Rgs, Romy the Cat

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

01-16-2011

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audiofilofine
Posts 29
Joined on 02-26-2010

Post #:	31
Post ID:	15429
Reply to:	15428

Tweeter field coil

Leaving open the magnetic flux to the nucleus is smaller and therefore the tweeter sounds much slower .
All the tweeter is in magnetic steel ( except in some parts ) but the magnetic force is concentrated on the core .
Since I use a translator to try to explain the difference I can tell you is the same drive the Magneplanar with a 10-watt amplifier or200 watt amplifier.

11-18-2013

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Kerry Brown
Posts 23
Joined on 03-22-2005

Post #:	32
Post ID:	20267
Reply to:	14192

Wolf Von Langa'sB&C DCM50 1428 clones

Romy,
To clear up a few things about the Kilimanjaro RCA1428 clones.
The B&C DCM50 is a modern, neodymium clone/copy of the RCA MI-1428B. It was designed and built by B&C in Italy after Bill Woods of AHhorns talked the CEO into it.
The DCM50 is not an exact copy of an RCA1428 obviously, with a different case, different diaphragm, different phase plug and a different motor but it's very close basically to the original design. The large center suspended paper diaphragm is the main reason it sounds so good.
It real does sound good. Bill Woods says the DCM50 on his 300 Hz AHhorn makes the most natural sound he's ever heard. That's a direct quote.
A few years back, I commissioned Von Langa to modify a pair of DCM50s to field coil operation for me. That is the genesis of the so-called A1428WVL.
That Wolf marketed them the way he did, has nothing to do with me, but I agree he should have mentioned they were modified B&C drivers. I notice he no longer markets them at all, perhaps B&C objected.

By the way I researched and provided the information on MI-1428s to Herr Von Langa back when we were planning the build.
As for f.c. voltage, my modified B&C DCM50s are fitted with 14V f.c. motors and work just fine with my inexpensive solid state PSs.
My drivers are on 12-sided conical 300 Hz AHhorns and they sound great - beautiful upper bass/lower midrange, very realistic sound overall.
The modded B&Cs replaced JBL 375s on 300 Hz tractrix horns. Compared to my 1428 clones the 375s sound tinny and artificial.
I am very very pleased with the way my 1428 clones sound. However, I would not be surprised if the unmodified neodymium magnet DCM50s sound just as good or even better.
Would be pleased to have you over Romy if you're ever on the West Coast and would like to check out the new horns and drivers.
Peace,
Kerry

11-18-2013

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	33
Post ID:	20268
Reply to:	20267

DCM50 and 1428

Thanks, Kerry. It was interesting. I never used neither RCA1428 driver nor it’s clones. I heard them I think once at Oswald Mils. It was for sure a pleasant midrange but it was nothing else wothe attention in there, so it is difficult to say anything. I hear a few times the Congent clone, I was not wild about the results but it might be the way in which Congent used their MF driver. I was not agree with their other design decisions so who know why the MF did not sound interestingly?

I never heard the B&C DCM50, it might be ended an interesting driver. I do have high respect to Bill Woods even though I disagree with some of his conclusions and even though he is associated with idiots in his business. For sure if the DCM50 has different diaphragm, different phase plug and a different motor then it is not the RCA1428. The center suspended paper diaphragm is very interesting however, even it have own design controversy.

I never heard the Herr Von Langa drivers. Any’s is trying to solicit me to do to South Africa to visit her brother who work in there as astronomer and if I do I might meet Von Langa and see what he does. So far , on the specks, I am not wild about his field coil conversions. He uses high current low voltage configuration but my observation of those type of the drivers suggest that they are too slow to me. I would be more interesting to hear 80V-120V drivers. However, if you feel that 375s sound tinny and artificial in comparing then it might be interesting. I do not think it is possible to find any common denomination in the drives evaluation unit we both listen the same installation and compare direct notes. It would be interesting to find a hypothetical MF driver that do the demanded job itself, with tonal injection, but I truly doubt that it might be possible, I have my reasons to feel this way.

Sure, if I hit the West Coast I would be gratefully to hear what you assemble, I know you have been experimenting with all of it for years. I do not have immediate plans to hit West Coast. For sure you will hear from me if I do.

Rgs, the Cat

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

11-19-2013

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Kerry Brown
Posts 23
Joined on 03-22-2005

Post #:	34
Post ID:	20274
Reply to:	20268

Try it you'll like it

Thank you Romy and congratulations on your website, it just keeps getting better and better all the time.

The RCA1428 is a great sounding driver on RCA multi-cell horns. Not that I like multi-cell sound. I have never heard an original 1428 on a tractrix or conical horn but my 1428-inspired B&Cs on AHhorns easily beat JBL375s on tractrix horns. No contest. My musician friends noticed the big step up immediately.

I would like to compare unmodified B&Cs to my f.c. version but not enough to buy a pair. From what Bill Woods says though, the DCM50 is definitely more than interesting.

The Cogent driver is not really a 1428 either, more of an upgraded version, same with the B&C driver I think. Try googling RCA1428B, and you'll find another 'clone' that looks more like the original 1428, that's made by Line Magnetics. They also make WE repro gear.

I attached a photo of the B&C DCM50 reinforced paper diaphragm, hopefully it will work.

Wolf calls his company Kilimanjaro because he spent time in Africa as a child but he lives in Bavaria. At least he did when he modified my drivers

I have never heard any of Von Langa's other drivers, he likes the Altec designs with multi cell horns so our tastes differ, but he does seem to know what he's doing with field coils. Apparently he's studied driver magnetics thoroughly and he's got some very sophisticated test gear. He sells some very cool looking complete systems too, mod deco style.

There is nothing slow about my modified DCM50s. The B&C drivers are more detailed, and 'faster' than 375s but have way better low frequencies. I have never heard any driver that sounds better. In fact nothing I have ever heard even comes close.

From what I understand the only reason high voltage motors were used on vintage drivers has to do with the existing power supplies, not sound quality. In any case, my 14V drivers sound wonderful. Dramatically better than 375s. No kidding. Maybe you should try a pair of stock DCM50s, I think you'd really like them.

11-19-2013

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	35
Post ID:	20275
Reply to:	20274

Interesting....

Kerry Brown wrote:
The RCA1428 is a great sounding driver on RCA multi-cell horns. Not that I like multi-cell sound.

Hmmmmm… If you feel that RCA1428 sound great in multi-cell then hat make it to sound different in single-cell? What I am saying is that I do not see any difference in driver performance between multi-cell and single-cell. A multi-cell, even 18 sections, if it properly made, is a proper exponential lording to the driver. Do you mean that in your assessment the RCA1428 sounds great with exponential loading but fail short with fast opening of tratrix or La horns? Anyhow, I am not competent to assess it one way or another as I never use them. I think the comments you made about RCA1428 sounds great or not great was in respect to the specific people use this driver in a specific applications. So, you commented about their application not about the driver itself.

Kerry Brown wrote:
There is nothing slow about my modified DCM50s. The B&C drivers are more detailed, and 'faster' than 375s but have way better low frequencies. I have never heard any driver that sounds better. In fact nothing I have ever heard even comes close.

If you feel that low voltage FC did not slow doe the transient response of the driver then you might run your output tube of your SET too ideal to compensate it. It is a legitimate way to deal with it, not unproblematic however as you lose power and a few other things. It certainly would be very interesting to hear it however.

Kerry Brown wrote:
From what I understand the only reason high voltage motors were used on vintage drivers has to do with the existing power supplies, not sound quality. In any case, my 14V drivers sound wonderful. Dramatically better than 375s. No kidding.

The power supplies reason is a urban legend. Sure there were some very cheap radios where FC of the drivers was integrated with choke of the power supply for plate voltage. For sure you do not reach that level of frugality in you hi-fi… The High voltage electromagnets does sound very attractive to me as all with no exception, including my own electromagnets drivers, did not sound right to me with having sunk transients being one of the many reasons. Remember the Congents? It was almost like hands covered with honey… Reportedly high voltage electromagnets are free from this problem. There was a brilliant guy from northern Europe who come to this site I think it was 3-4 years back. I do not remember who it was but he did what I did – converted drivers to electromagnets and was trying to make them to sound right. He reported that all problems were addressed with high voltage coils and his enumeration of the addressed problem was spot on. Id did not try high voltage myself but his report was very plausible in my view.

Kerry Brown wrote:
Maybe you should try a pair of stock DCM50s, I think you'd really like them.

Maybe, I do not have an itch to try anything new. I have quite unique combination of YO186+S2+Injection and I can only assure you that people out there have no idea how it sounds. I might be with my MF sound way behind the curve or a way ahead the crowd, I do not know, not do I care. So, far the MF that I get does fulfill my understanding how MF might/shall be. When I hear what people do out there I do not particularly appreciate it but frankly I do not invest a lot of time listening other people audio. This Thursdays an industry guy will be coming to my listening room for a listening session. If he after listening would tell me that smart people out there long time ago surpass the quality of MF that I have in my room and will be able to name the specifics then I might look at what is available out there. So, far no one complained, neither do I. I did not try anything else in MF for years. It is very possible that this new B&C DCM50 is very good driver. I am glad you like it and it looks like some other folks like it as well. I am glad that drivers are progressing. What would be fun if some crazy Bulgarian nuts would take that DCM50 and replace paper suspension to a very fine leather, that would be even more interesting…

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

11-20-2013

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Kerry Brown
Posts 23
Joined on 03-22-2005

Post #:	36
Post ID:	20277
Reply to:	20275

High Voltage ?

Years ago, the two different systems in which I heard RCA 1428s - in a fairly big warehouse and crammed into a basement listening room - used giant RCA multi-cell horns in combination with giant Ubangi bass bins, passive crossovers and vintage WE or Telefunken tube amps. Both systems sounded very good considering what they were, and the sound of the 1428s was clearly different, better, than similar systems I heard in the same rooms which used WE 555 and or JBL 375s.
Those giant systems sounded completely different than mine of course. I only use straight horns, except for the Edgar Seismic Subs. I multi-amp with Class D machines, my crossovers are DSP processors, I don't try for broad dispersion my sweet spot is very narrow, on and on. My setup is not similar to 'vintage' theater systems. But the 'sound' of the 1428s in those vintage systems was still very good - relative to other cinema type systems - and mentally translatable to my sort of 'studio monitor' system.
As you say though, to fairly evaluate a specific component it must be plugged into a familiar system.
I can't speak to the differences between high voltage and low voltage f.c. drivers as I have never listened to a high voltage f.c. driver. In fact, I have never seriously listened to any other f.c. drivers besides mine. However, I have lived with and listened to many other drivers, including Vitavox S-2s, Altec 288s, JBL 375s etc., etc., and compared to any other driver I have heard the modded B&C's are clearly superior. In my system, and by logical extension, in any system.
I do know that folks who have tried high voltage versions of the 1428 have remarked that the sound is not much different, if different at all, than the low voltage version. In any case, it would be interesting to compare if someone can fabricate B&Cs with high voltage motors.
I will read up on your YO186+S2+Injection idea, I'm sure it sounds good if you are satisfied with it. I am just saying there's something out there that clearly, obviously sounds better than any metal dome drivers I have ever heard. And it's not expensive. And it's easily available.
Using a chamois outer suspension may be a good idea. The Cogent boys do it. I am very pleased with the sound of the paper diaphragms but I do have two spares, maybe I should give leather perimeter suspension a chance.
Anyhow, wish I could attach a photo of one of my spare diaphragms, it's quite different to the usual metal dome. I will give it another shot, any tips if it does not work ?

11-20-2013

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Paul S
San Diego, California, USA
Posts 2,658
Joined on 10-12-2006

Post #:	37
Post ID:	20278
Reply to:	20277

Perfecting Perfection

Kerry, thank you for sharing your paper diaphragm idea. Very interesting. As I remember it, the Cogent diaphragm I saw (and listened to) at Steve and Rich's place was a flat disc of something like fiberglass, and it looked relatively heavy for the application, compared to the usual compression driver alternatives. Withal, used as I heard it, the sound was truly phenomenal in a narrow band around (I think...) 700 Hz. I have no significant experience with the original RCA drivers.

You mention that you use all Class D amplification. Does this mean you also use a "pro" type, digital solution, or something like this, for your crossovers, including LF loading, or perhaps you even use shaping?

Of course, leather suspension is not really a solution but just an alternative. At this point I think the root question is one of movement vs. damping of that part of the cone and whether a particular application (of leather or whatever) happens to address and/or facilitate a particular behavior in a particular, +/- controlled situation.

Best regards,
Paul S

11-20-2013

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Kerry Brown
Posts 23
Joined on 03-22-2005

Post #:	38
Post ID:	20279
Reply to:	20278

Paper diaphragm

Hi Paul,
The Cogent diaphragm I have seen pictures of was woven carbon fiber with a leather outer surround. I have never listened to a Cogent 1428 but they must sound very good, at least Bill Woods and Bruce Edgar say so.
Besides their overall ultra clear and natural 'sound' the B&Cs big advantage over most compression drivers is its low frequency extension. My 375s had weak response near the 500 Hz crossover point I use, but the DCM50s are very strong.
My system is 4-way using 2x DEQX HDP-4 processors; 2xNuForce mono amps on the midrange horns and 6 x channels of a 7-channel NuForce HT amp that uses the same circuit.
The DEQX processors function as crossovers, speaker 'correction', room correction devices and equalizers.
My bass horns are 80 Hz straight Edgar horns, tweeters are HiVi slot-loaded planar magnetics and I run a pair of Edgar Seismic Subs.
There's a photo of my system attached to this post. Politically incorrect, but it sounds good.
A leather suspension could be rigged up I guess but I like the B&C paper diaphragms as they are. Why fix it if it ain't broke ?
By the way, did you open the attachment on my last post of a photo of the B&C diaphragm ? Doesn't seem practical to modify it, you'd probably have to start from scratch.
Anyway, I was not exaggerating the major step up in sound quality of the midrange horns in my system vs. any others I have tried. I think it's a real breakthrough driver. Instruments and voices just sound way more real with the DCM50.
I'm curious if any other club members own the DCM50, or know anyone who uses them. I wonder if anybody else is as stoked on them as I am.

11-20-2013

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Paul S
San Diego, California, USA
Posts 2,658
Joined on 10-12-2006

Post #:	39
Post ID:	20280
Reply to:	20279

Application

Kerry, from what you have said so far, I am not surprised that you have gone whole-hog digital. I see that yours is an HT system. The first thing anyone here would say is, physically time-align your HF, although I suppose you "could" do that with DEQ/group delay...

Yes, I saw the photo of your paper diaphragm, and I would say that if you want to mess with it then adjust/play with the edge damping with clamping and/or various doping materials and methods before you bother with leather, although leather would certainly change the sound. Haralanov is the local expert on this.

I'm pretty sure the early Cogent diaphragms I heard were fiberglass/resin, not carbon fiber. The CF could possibly improve the strength/weight ratio somewhat, and it would change the damping, for whatever that would be worth. Again, the units I've heard sounded very nice indeed over a very limited bandwidth, driven by their SETs, listening to fairly simple music.

I never owned 375's, but I sure wanted to, for many years. For consumer applications, JBL always hooked them up to their "lenses". Very smooth, even response compared to any other drivers of the day. I've never heard them in a fast, simple horn, but I know the JBL engineers did tweak their drivers, depending on the "application", and to my knowledge they never used turned wooden horns nor optimized their drivers for them, like we do now.

The dream (with any driver...) is to have a useful octave to "spare" on either side of the X/Os...

Best regards,
Paul S

11-20-2013

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Kerry Brown
Posts 23
Joined on 03-22-2005

Post #:	40
Post ID:	20281
Reply to:	20280

HT vs. 2 channel

Paul,
The two channel system is separate from the HT system - the gigantic plywood folded horn subwoofers support the screen but that's the only connection to the HT audio system.
The HT system is three Orb Audio 8" powered subwoofers, 3 x Gallo Ref. Stradas for L,R&C and Orb Audio side and back surrounds on all on a Pioneer AVR.
The tweeters are obviously not physically time aligned - not sure that's especially important considering they are filtered at 5kHz but they are electronically time-aligned and phase corrected,
Don't feel any desire to mess with those diaphragms actually, happy with them as they are.
I don't know what Cogent's diaphragms are made of but they are probably still carbon fiber from what I have read online and from what Steve has told me.
I used to think JBL 375s were about the best thing going but the B&Cs are so much better it's ridiculous. As for compatibility, the geometry of the 375 is not optimized for fast opening horns like cones and tractrix designs, it sounds better on slower opening big exponential horns. Actually modern hockey puck style JBL drivers are better on rapid expansion horns.
My bass horns are weak at 500 Hz and so were the JBL375s, upper bass was barely there. The B&Cs are good to 400 Hz, the quality of upper bass/lower midrange is the best I have heard from any system.
Best Regards,
Kerry

11-20-2013

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	41
Post ID:	20282
Reply to:	20281

Meow?

Kerry Brown wrote:
My system is 4-way using 2x DEQX HDP-4 processors; 2xNuForce mono amps on the midrange horns and 6 x channels of a 7-channel NuForce HT amp that uses the same circuit. The DEQX processors function as crossovers, speaker 'correction', room correction devices and equalizers.

….

The tweeters are obviously not physically time aligned - not sure that's especially important considering they are filtered at 5kHz but they are electronically time-aligned and phase corrected….

Kerry, dear, you needed to preface your comments about DCM50 driver by mentioning that you use digital crossovers for doom correction and digital amplifiers. Anyjow, I wonder what you do not watch movies then what music do you listen?

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

11-21-2013

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Kerry Brown
Posts 23
Joined on 03-22-2005

Post #:	42
Post ID:	20285
Reply to:	20282

You must hear it to believe it

Romy,

Why preface my comments ? I've had the same system for 10 years basically.

I do use digital crossovers but the 'Class D' NuForce amps are not digital at all. And the NuForce amps don't sound like stereotypical Class D amps, they are very quiet, dynamic and sound very natural. The DEQX crossover/processors don't sound 'digital' either.

I realize my setup is strange but it works very well. I know it's hard to believe but my stereo sounds closer to real than any other system I have listened to. Not that I have listened to all that many systems other than poor setups in stores and at shows.

The home theater is fun, I like movies, but the audio is not serious. The two channel system is serious.

I listen to all sorts of music, a lot of New Orleans brass bands lately, Dirty Dozen, Rebirth Brass Band, stuff like that. The new horns are really good on the bass drum and tuba parts and easily decongest crowded soundscapes.

But I like it all, electronica, bluegrass, classical, blues, flamenco, hot jazz ( love Django ), bebop, big band, whatever, everything.

By the way, 80s/90's SoCal audiophile speaker maker Paul Hales new company, Pro Audio Technology, make expensive home theater horn systems that are Class-D multi-amped with DSP crossovers. His systems are kind of along the same lines as mine, sort of. His statement system midrange horn uses a 41 lb. compression driver with a carbon fiber diaphragm. The only driver I know of like that is the 40 lb. carbon fiber diaphragm Cogent 1428. Interesting.

http://www.professionalhomecinema.com

11-21-2013

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	43
Post ID:	20286
Reply to:	20285

OK. Thanks.

Kerry Brown wrote:
Why preface my comments?

Because it helps to put your comment in objective perspective. It is internet and people express opinions without any tangible common denominators of reference points. I might make a comment that I drive my 87dB sensitive loudspeaker in 700 sq feet room with my 2A3 SET and have excellent sound. I can even say that I have it for 10 year and never feel that anything wrong. For a person who would listen my comment my judgment would be important but the key words of 87db and 2A3 would allow to correlate my assessment with anybody else experience.

For sure I am not saying that your installation does not sound good with your bluegrass. But you shall agree that sound you are getting is to a degree bounded to DEQX, digital amps and your feeling that misaligned tweeter does not matter. I understand that they don't sound 'digital' to you, I wonder what you feel sound 'digital' is but this is not the question that requires an answer.

So, I feel that proper perspective does help to interpret the comments and I do feel that it is good thing.

The DCM50 still indeed is an interesting driver to try. I do not think that I will try it. I have 1.5” throat and DCM50 is 2 incher, + the DCM50 has a different location of diaphragms, so it would be a day-long project to me to try it. I however will keep my eyes open and if I will see within a rich somebody who use the DCM50 then I will make sure that I will listen it. Thank you for pointing the driver out and for the pictures.

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

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