B&C DCX464 Coaxial, LeCleac'h Azura horn and Dual 18" Speakerbuild

[davewantsmoore]

On 21/5/2024 at 11:40 AM, La scala said:

Look at the graph , the BnC is low on SPL till 450hz. 

Sure you can suck the guts out of it to flatten the response with DSP , but...

 

Personally jerked around with a BnC DCM50 in various horns from 300hz up , the mother driver never like much under 500hz at all and suspect yours possibly be likewise.

 

The DCX464 measures like this (no EQ) , on the horn that B&C designed for it (a ~300Hz horn)

 

 

 

Near-field data is spliced with with windowed (far) data.... which I reckon you can see at ~600Hz (they didn't say what frequency).

 

 

So it will be fine to 300Hz with the right horn .... but of course (as I mentioned above somewhere), the driver first impedance peak is big and at 300Hz, so a horn which loads at a lower frequency is not going to do it any favours whatsoever.

 

 

Edited May 22 by davewantsmoore

[playdough]

18 hours ago, davewantsmoore said:

loads at a lower frequency is not going to do it any favours whatsoever.

 

 

THe first 2 paragraphs of this statement will cause wringing of hands, and gnashing of teeth, but, is worth a quick read.

After quote

Maybe so, however I intend to try and see if with a little DSP convolving, the driver over time can be pushed a little harder (at 100dB or less) after run in and as its suspension softens up.

 

Drivers really do that,,,yea if you built speakers/enclosures and extended testing of years you would recognise that.

 

It will only ever be run at up to 1% of its actual power rating as it's a high end very, very  high power Pro Audio driver, we are talking about here a driver that is coined as "the Loudest Speaker in the World"

 

I tend to look at my experience with actual outcomes of all the drivers I have done this with and in particular Pro Hi Efficiency Drivers of all types, looked down upon mostly in HiFI,

Results do,,,,, frankly end up being real.

 

The case of the 21" Drivers, resonant frequency of 40Hz, it was tested in the Lab and had a roll off in FR of F3 at 50Hz loaded into it's designed  enclosure.

Trouble is now in combination with the ported enclosure, and a little tickle from the DSP, F3 @12Hz and up at insane efficiency levels at 1/5mm excursion  is the real, measurable response and was harassed by the Nay Sayers all the way, much to my delight and last giggle I might add.

 

Now the speakers suspension is just becoming more and more compliant to its new "job" and just gets better in character year after year of service and provides listeners no end of amazement

 

I learned a lot from that job.

 

THis system as the one before it, and the one before that and as specified, is an integration of all components, including everything set up so as to facilitate a speaker system including Power Amplification and DSP, with digital input.

 

Martin a very experienced speaker builder and I are experimenting at my cost and to be honest and after a conversation of your concerns happen to agree

 

That we are both satisfied this may well work quite well as I am trying to create   a narrowing propagation pattern through rising frequency to emulate another of my favourite speakers, that is a bipolar, the Electrostatic, without the annoying limitations and with and unknown character ATM

 

Most likely slightly narrower propagation of sound output, generated lower down the throat of the Azura Horn. I stand by my statement as a speaker builder, you might be wrong, jumped the gun

 

As far as the high impedance of the coil at 300Hz is concerned, that may well be an attribute of the designed aperture horn and looking it's only 4 dB down from my target.300Hz, the LeCheach will load it differently and without you Dave doing a simulation, you will never know, ,,,,what I do.

 

If that means nothing to you, then so be it, my new adventure,

 

If it fails to meet a satisfactory level of performance after a period of time and measurements, hey, I'll have made a second smaller Azuahorn, use a Lowther paper cone 8"  (in the Horn in commission right now) , which can happen with my new actual build W/O any modification and integrate it with asaid smaller Azura horn with a JBL CD on hand, a pair (of your paperweights) I purchased off you in fact, Dave, do you remember ??

I've future proofed this project for the cost of a pair of papercone 8" and little horns, might be red ones to match my decor in the brand spanking new reno.

 

It's not the first time a set of (insanely expensive) drivers here have ended as paperweights here and over time will (could)  invent another speaker system, with the B&C Coaxial and a more suitable horn, more in the ridgid Laws of domain you speak of.

 

THe Journey may not be over, it's over when it is,,,,,,,,,,,,,,,,,

 

playdough

 

 

 

 

Edited May 23 by playdough

[playdough]

17 hours ago, La scala said:

Sorry to hear about your second driver blunder , sure hope assitance comes your way to sort it out quick smart for you.

Not much seem to function out there of late in general.

I have one question thats troubling me in regards to which cucumber suggested the driver will suit a 300hz baseline ?

Keep up the good work 

One way or another a driver will show up.

I did a study of its current local, this may be a way point (Choke point of administrative affairs)  that things end up at, that are then handled by EBay International Shipping. It appears that the seller, may well have completed it's obligation after all,,,,,,,,,,,,TBA however.

Down to 300Hz, read above.

and Thanks

[playdough]

Better get out the drawing board  buy some icy pole sticks at spotlight build a scale model, it's a really big job has to look good (bass enclosures need to strong things, heavy). Wood veneer this time,  rather than a roll on paint. 

I could have either bought the AH- 204 or AH- 340 Azura, I went to the 204, because it'll look better with the 18" s, took a punt on the loading might be ok, just looking at them,  Adding a small red 1200Hz horn, Does actually row the good looking boat and no problem to integrate into the system, mentioned this to Martin, might make a nice carton all in, packed in there 4 horns and adaptors. 

 

I do believe a throat insert might relieve  the driver reactance, if there are problems, in a good way 

 

 

 

 

Edited May 23 by playdough

[davewantsmoore]

On 23/5/2024 at 11:15 AM, playdough said:

Maybe so, however I intend to try and see if with a little DSP convolving

 

My concern isn't about the overall SPL response ... or whether the driver can "handle it".

 

It's is by placing the wrong acoustic (air) load in front of the compression driver that the sound through the frequency ranges where the impedance is not flat, will be compromised (not sound good, or at least, not as good as normal).

 

On 23/5/2024 at 11:15 AM, playdough said:

if you built speakers/enclosures and extended testing of years you would recognise that.

I'm not sure what you mean here.  Can you clarify?

 

On 23/5/2024 at 11:15 AM, playdough said:

It will only ever be run at up to 1% of its actual power rating

That doesn't have any bearing on the recommendation not to use a too big horn.

 

On 23/5/2024 at 11:15 AM, playdough said:

the LeCheach will load it differently and without you Dave doing a simulation, you will never know, ,,,,what I do.

Yeah, I did one.   It's hard to put a compression driver in the hornresp program ... but you can do an ok job if you fiddle.    Not that it really tells you that much, aside from what is obvious.

No, not really that much (differently "loaded") than other.

 

Yes, you'll get a drooping response at lower frequencies... but that wasn' why I said I wouldn't recommend doing it.

 

On 23/5/2024 at 11:15 AM, playdough said:

which can happen with my new actual build W/O any modification and integrate it with asaid smaller Azura horn with a JBL CD on hand, a pair (of your paperweights) I purchased off you in fact, Dave, do you remember ??

I had forgotten.

You bought some old/spare JBL compression drivers from me. Yes?!

 

On 23/5/2024 at 9:12 PM, playdough said:

do believe a throat insert might relieve  the driver reactance, if there are problems

You mean like making an extra "phase plug" to put in the horn throat.

 

It may/could to some extent.... it will do so by narrowing the horn area/expansion in the throat end (changing the horn back towards a high frequency horn) ... but then it will be tending towards a horn size/shape that you should have used (eg. --> 300Hz) ... but with a mouth size and expansion which is too large. <shrug>

 

 

Anyways.  That's more than enough from me now.

[playdough]

8 hours ago, davewantsmoore said:

 

My concern isn't about the overall SPL response ... or whether the driver can "handle it".

 

It's is by placing the wrong acoustic (air) load in front of the compression driver that the sound through the frequency ranges where the impedance is not flat, will be compromised (not sound good, or at least, not as good as normal).

 

I'm not sure what you mean here.  Can you clarify?

 

That doesn't have any bearing on the recommendation not to use a too big horn.

 

Yeah, I did one.   It's hard to put a compression driver in the hornresp program ... but you can do an ok job if you fiddle.    Not that it really tells you that much, aside from what is obvious.

No, not really that much (differently "loaded") than other.

 

Yes, you'll get a drooping response at lower frequencies... but that wasn' why I said I wouldn't recommend doing it.

 

I had forgotten.

You bought some old/spare JBL compression drivers from me. Yes?!

 

You mean like making an extra "phase plug" to put in the horn throat.

 

It may/could to some extent.... it will do so by narrowing the horn area/expansion in the throat end (changing the horn back towards a high frequency horn) ... but then it will be tending towards a horn size/shape that you should have used (eg. --> 300Hz) ... but with a mouth size and expansion which is too large. <shrug>

 

 

Anyways.  That's more than enough from me now.

Cheers Dave

All good, some interesting observations made.

 

We are at the "wait and see" stage, fairly typical when the hardware isn't present.

I'll be able to completely test and listen to the FR, observe and try measure some sort of rudimentary polar plot, that and asses it's character or, weather it sounds bad or not,,,,,,,,,,paired with the 21' ported walrus enclosures, which are "known to be a reasonable bass maker"

 

 

[sleach]

12 hours ago, playdough said:

21' ported walrus enclosures,

What are those??

[playdough]

9 hours ago, sleach said:

What are those??

2 x 650 litre dual 21' bass reflex enclosures.

The most fun bass speaker ,,,,,,,, pass band w/o EQ, F3 is 25Hz, to 500Hz +, with DSP can be driven into sub sonics, with vanishingly low cone excursion/linear distortion (a few mm), although a lot of work on the listening zone and room with limp, weighted membrane bass traps was employed  to make the most of them.

Good test bed for almost any HF Section. I love the PSE although working toward a narrower dispersion and a better looking speaker system, these large enclosures will go eventually replaced with 18" line arrays. AE TD18" and Maelstrom 18" under 200 litres, each.

[sleach]

2 hours ago, playdough said:

2 x 650 litre dual 21' bass reflex enclosures

Blimey, thats a lot of litres

[playdough]

3 hours ago, sleach said:

Blimey, thats a lot of litres

The surprise was the actual efficiency, suitable for valve Amps very easy load to drive.

[davewantsmoore]

On 25/5/2024 at 9:11 AM, playdough said:

We are at the "wait and see" stage, fairly typical when the hardware isn't present.

You did a sim though right?

 

There's no secret as to how it will perform (that the response vs angle will be).

 

It will likely sound fine, especially after some correction to sort out the low end of the passband (early rolloff, due to mismatched loading) .... but you would get the just same response than with the ~300Hz horn.

 

On 26/5/2024 at 1:00 PM, playdough said:

The surprise was the actual efficiency, suitable for valve Amps very easy load to drive.

Not so efficiency at the very low frequencies due to the fast/high rolloff and large amount of boost required to get a flat response....   but that's not to throw shade on it.   Almost all drivers of this size/application are like this due to their high motor strength.

[playdough]

3 hours ago, davewantsmoore said:

You did a sim though right?

 

There's no secret as to how it will perform (that the response vs angle will be).

 

It will likely sound fine, especially after some correction to sort out the low end of the passband (early rolloff, due to mismatched loading) .... but you would get the just same response than with the ~300Hz horn.

 

Not so efficiency at the very low frequencies due to the fast/high rolloff and large amount of boost required to get a flat response....   but that's not to throw shade on it.   Almost all drivers of this size/application are like this due to their high motor strength.

Yep, correct. ATEOTD I'd rather something that looks good, better than good, yes it's a sad approach I know,,,,,,,,,,,,however there was discussion, simulators (which I cannot show) and much gnashing of teeth, sleepless nights, etc. the 340 is just too small in circumference, to suit the 18's,,,,,,,,,hec,,,1 octave,,,,ok, here we go.

I'll buy a pair of Azura 340's when the dust settles here, full turn back aperture. THat will mean I will have a full set of Azura Horns, to play with. 

There is a raging barn fire by the name of Francesca, a rather animated and passionate  Italian Lady who is the Commissioner in all aspects of the project. 

I'm out of here for a week,,,,,,,,,,,,she needs,,,,,,,,,assistance, I'll render that in every way/ I can.

 

Edited May 27 by playdough

[playdough]

3 hours ago, davewantsmoore said:

Not so efficiency at the very low frequencies due to the fast/high rolloff and large amount of boost required to get a flat response

That's where the 2.2Kw Power Amplifier array comes in handy and even then, clean brutal sub 20Hz at very low cone excursions. 

I can drive them them to 10mm ,,,,,,,,,,all 4 off, clean and tight, beyond  is just  too much for a human being  to bare, literally.

 

EDIT, with regard to the loaded point source, phase linear coax. An idea, why not stack some felt rings at the horn aperture around the point of falling magnitude and rising impedance of the coil. Provide some more resistance at 300 , maybe,,,,,,,,,,,,,It's not over yet ....  

Edited May 27 by playdough

[playdough]

7 hours ago, davewantsmoore said:

high motor strength.

Is a must for dynamics....

[playdough]

Arrived home after a week away to find that EBay buyer protection is not worth a cracker.

I'll have to buy in another coax or other drivers to get a start with this project.

Not impressed.

WARNING< DO NOT USE EBAY TO BUY they won't protect your purchase, while fleecing everyone money in fees. ,,,,,,,,,,,sad I know, however truth.

 

[playdough]

On the other hand a driver is available in Australia and that will be purchased.

A Triton work center is here waiting to be set up and the job is not going to stop because of a few hic ups and a few bucks.

Have to draw up a plan,,,,Thinking about a laminated strip, cooped style construction, MDF.

Onward, in true Tradie style. 

[playdough]

I can't help playing, set up a system for a 40 foot bus/camper. These will go upside down in front of the wind screen about 900 surface mounting on console to release brackets. 12v 50w supply.  Good if on axis to these, nice soundstage. with sub. Made out of a parts bin sale of these odd 7" drivers, tweeters needed attention with the crossover, go ok, for the bus. little bt amp is ok.

[sleach]

On 08/06/2024 at 6:55 AM, playdough said:

On the other hand a driver is available in Australia and that will be purchased

A replacement B&C coax or something different?

[playdough]

7 hours ago, sleach said:

A replacement B&C coax or something different?

Yep a replacement for the B&C 464-8 coax.

Did some work, set up and doodle. Saw might need a half mm tap with a hammer. Just really wanted to have an idea of internal volume/relative appearance and enclosure size, which is all go and plenty of volume for bracing and bricks/cement.triple lam for baffle . Might curve the side into baffle as well as the back. 1160 x 650 x 550mm, is a guide (external measure) Template a top would be next. 

got a feeling 2 part  bodyfiller is going to be my friend on this job.

Edited June 9 by playdough

[davewantsmoore]

On 27/5/2024 at 4:52 PM, playdough said:

EDIT, with regard to the loaded point source, phase linear coax. An idea, why not stack some felt rings at the horn aperture around the point of falling magnitude and rising impedance of the coil. Provide some more resistance at 300 , maybe

The issue is the size of the mouth.

 

You can (very roughly) simulate this with (even something "basic" like) hornsresp to see it isn't going to help at all.

[playdough]

4 minutes ago, davewantsmoore said:

You can (very roughly) simulate this with (even something "basic" like) hornsresp to see it isn't going to help at all.

See how she goes Dave, the bass cabs will be cool. 210mm higher than a 200 litre barrel & wider, considerably smaller then than current set up. Litres to burn. Going to minimise the width of the baffle face and rear plate to a degree, should be strong enough with bracing.

[playdough]

So  started   a full size model. In reality there is no escaping from these not being large floorstanders, the 18's are larger...Trim this a few mm here and there cut accurately a top template, to make jigs. Had to do a 1:1 scale to get a good look at it in the room.

They will be heavy.  40mm laminated sides, 60mm baffle and rear . The coping strips can be cut all the same size/angle as it is a radius 

 

Azura Horns are not far away. 

Edited June 10 by playdough

[playdough]

The wind has blown a 20m section of paling fence down, so that will take a day or 3 to rectify !

Missing Driver, B&C DCX464, from Ebay, might get a refund through Visa at this point after a chat to my Bank.

Ebay = Bad.

[playdough]

Needing a set of horns ! 

Nice to see this job, delivered ,,,,,,,

[playdough]

More good news for the project.

Martin and I have been happily chatting for a few weeks now (about bass mainly, surprisingly) and he reports the horn sets are almost finished with the AH-205 on the spinner for final finish. Throat adaptors and drilling/studs are all done.

THis was the "may as well as there is room in the carton" job.

 

Some JBL2425 Compression drivers that are one of my favourites have been lying about here for a while. They have been loaded into JBL Aperture Wave Guides and Bi Radials for fun and evaluation and now as a bonus, let me introduce the AH-1100, full roll back LeCheach horns, completed/drilled finished and mounting studs provided, for my CD's

Thanks Martin, these look lovely.

Edited June 19 by playdough