B&C Compression Driver and Horns

[ZilchLab]

Thanks for that. So the JBL drivers are not worth the extra outlay? I always thought it would be nice to have an all JBL system, however it seems that perhaps there is better value to be had elsewhere.

I'm not saying that, rather merely addressing your inquiry with respect to where to purchase BMS 4552nd.

This is DIY. Accept Brett's offer of a free P-Audio 2370A clone, stick a JBL 2425/6/7 H/J on it, (saw one on eBay for $50 BIN needing diaphragm yesterday,) mate it with JBL 2225/6 H woofer, and use EspenE's crossover design.

JBL has sold thousands and thousands of that system into SR and theater applications. See if what you always thought it would be nice to have works for you....

 

[gedlee]

Thanks for that. So the JBL drivers are not worth the extra outlay? I always thought it would be nice to have an all JBL system, however it seems that perhaps there is better value to be had elsewhere.

Another outrageous GedLee opinion here! Be forewarned!!

Drivers are a commodity, I can make a good system out of any of them - as long as they meet some minimum standards. I have done systems with drivers over a range of about 10:1 in price and found that none of them made much difference. I evaluated a compression driver from China that was a virtual copy of the DE250, worked pretty well - it was $15.

Its the acoustics of the system that matters not the drivers. The waveguides matter alot, the cabinet acoustics matters, the crossover design is critical, but I can make any drivers work.

I just measured a cheap Emenance driver. It would work fine.


There is no correlation between cost and sound quality. There is a strong correaltion between the system design and the sound quality.

 

[GM]

Help me, now - we should only make two-ways using 755As or equal as woofers, and having horns and compression drivers that play below 3.5 kHz is pointless?

??? The 755A or other driver optimized for human speech is a very poor choice for a woofer or tweeter, so should be limited to the BW it was designed for in at least a three way system.

??? I said/implied nothing about the applicability of compression horns in other BWs and I don't care what kind of driver system it is or for that matter the number of XO points, I don't recommend a XO in our acute hearing BW for a high SQ HIFI or HT sound system, so since this is a tweeter horn it's only good for a high XO point IMNSHO.

FYI, I've been either compression horn or WG loaded from 70 to 500 Hz (depending on the mid-bass/lower mids system) - 20+ kHz since 1960 and if you do a search you'll find I recommend such systems every time it's appropriate, so Hell will probably freeze over before I recommend not using them in our acute hearing BW.

All that said, while I currently have a mildly tweaked Altec 511/802 horn system for the 500 Hz - up BW, I don't recommend any horn loaded system in our acute hearing BW for a high SQ HIFI or HT sound system since no matter what you do they still 'color' the sound to a greater or lesser extent either on and/or off axis, so for this BW I recommend a WG over even a Tractrix regardless of driver choice, of which I prefer compression loaded.

GM

 

[gedlee]

I would concur that no crossover should ever be between 1 kHz and 6-7 Khz. There is no such thing as a "good" crossover, only ones that are "not so bad". But they have to be out of the critical hearing range as claimed above.

To me, ONE of these "evil demons" is all I can tolerate in a system. In that case, 1 kHz is about the only option. No compression driver can go lower AND get to above 10 kHz. No driver of any kind for that matter - at least not with any efficiency.

 

[warnsey]

Gedlee, thanks for your honest opinions.

So it seems like it could be the:

B&C DE500

or the

BMS 4540ND (if I can't get the 4552ND)

 

[ZilchLab]

??? I said/implied nothing about the applicability of compression horns in other BWs and I don't care what kind of driver system it is or for that matter the number of XO points, I don't recommend a XO in our acute hearing BW for a high SQ HIFI or HT sound system, so since this is a tweeter horn it's only good for a high XO point IMNSHO.

Yes, I'm getting that.

You seem to have defined acute hearing bandwidth as encompassing 500 Hz - 7 kHz, in which region no crossover is tolerable for a high sound quality Hi-fi or home theater system.

I thought for a moment I could get there with a horn covering everything from 500 Hz up, but now you're saying horn coloration precludes that as an approach.

Thus, it would appear that a "high SQ HIFI or HT two-way" is unachievable according to these criteria?

 

[ZilchLab]

BMS 4540ND

To mate with what woofer that will play competently up to 2 kHz?

 

[gedlee]

Gedlee, thanks for your honest opinions.

So it seems like it could be the:

B&C DE500

As I said before I prefer the DE250 or DE160. The mylar diaphragms just seem to work better than the titanium ones. At least for sound quality So why pay so much more for a driver thats not really as good for the application?

 

[GM]

You seem to have defined acute hearing bandwidth as encompassing 500 Hz - 7 kHz........

Well, it's more like 120 - 7000 Hz at typical HIFI/HT average SPLs, but as EG noted, something has to give, so to keep horn/WG/driver size semi-reasonable, the bottom end normally gets compromised, though how much tends to be a design trade-off based on size and/or power handling requirements.

With horn loading, ~500 Hz is a practical lower limit if you consider a ~2 ft. deep cab acceptable in a 'mini-me' world, but a WG of ~the same size is only good for ~700 Hz with barely enough efficiency to mate to a wide BW HE woofer once EQ'd flat, so you pick your trade-offs whether horn or WG loaded.

If I ever bother to build up another high SQ system for myself though, it will be with a quasi-two way comprised of a sub system and three way Unity concept system since when done right its XOs are transparent to my ears and offers superior performance to any traditional wide BW two way I've auditioned.

GM

 

[warnsey]

To mate with what woofer that will play competently up to 2 kHz?

A mighty good question, any suggestions?

 

[warnsey]

The Beyma CP385ND looks like it could be crossed at around 1000khz. Anyone heard this driver?

 

[GM]

To mate with what woofer that will play competently up to 2 kHz?

I don't keep up with driver specs, but we can narrow the search a little by determining its size since it depends on the desired coverage angle at this frequency, which in turn is a function of speaker spacing Vs listening distance. For instance, ~90 deg. is a good choice for most situations, so it ideally needs a ~9" effective diameter (Sd = ~63.62"^2/410.433 cm^2). Being an odd size though and since 2 kHz is where our hearing acuity peaks, narrower is better than wider, so dropping to 80 deg (assuming there's a WG available) let's us use a ~12" wide BW woofer.

GM

 

[gedlee]

I don't keep up with driver specs, but we can narrow the search a little by determining its size since it depends on the desired coverage angle at this frequency, which in turn is a function of speaker spacing Vs listening distance. For instance, ~90 deg. is a good choice for most situations, so it ideally needs a ~9" effective diameter (Sd = ~63.62"^2/410.433 cm^2). Being an odd size though and since 2 kHz is where our hearing acuity peaks, narrower is better than wider, so dropping to 80 deg (assuming there's a WG available) let's us use a ~12" wide BW woofer.

GM

I'd also like to point out that drivers are not flat and the directivity tends to be wider for a cone that a flat piston. My "rule of thumb" is that a 12" driver is about 90° at 1 kHz.

And I'm not sure that I follow the statement you made:

With horn loading, ~500 Hz is a practical lower limit if you consider a ~2 ft. deep cab acceptable in a 'mini-me' world, but a WG of ~the same size is only good for ~700 Hz with barely enough efficiency to mate to a wide BW HE woofer once EQ'd flat, so you pick your trade-offs whether horn or WG loaded

But if I do I don't agree with it. Why does a horn load any differently than a waveguide. That seems to be what you are implying and I don't agree that it does.

 

[col]

B&C DE10-8 Dayton HR10RW Selenium ADM25-25

Hi,

Hope this thread isn't dead. I'm interested in having a go at seeing what can be done with waveguides on a limited budget (bang4buck), say $400-500 and with limited access to tools. I have purchased a pair of B&C DE10-8 Mylar compression drivers, Dayton HR10RW waveguides and Selenium ADM25-25 adapters, which have just arrived from PE. Pictures here:

http://pix.minirig.org.au/main.php?g2_itemId=588&g2_navId=xcc08e8f9

My idea is to modify these parts to get the optimum performance out of them without too much hard work involved. I plan to mate them up with a pair of 10" 4ohm 150W 93db Chinese made mid-bass drivers in a 25-30ltr sealed cabinet.

They will be powered by a 4 channel 41hz.com amp9 kit and crossed using a Elliot Sound Projects P09 linkwitz riley 24db electronic crossover set at 2khz. I won't be doing anything too woodwork intensive with the baffle, apart from cutting a couple of holes in it for the drivers and planing any hard edges. I am hoping to round the corners by gluing neoprene cut to the size of the drivers and stuck in place around the enclosure.

The tools I have available are:

Dayton WT3 Woofer Tester
Behringer DEQ2496 with a ECM8000 measuring mic
assorted power tools including jigsaw, drill etc..
hand tools, files etc..

So, any ideas for mods?

 

[stoN_Cold]

Hi ti All!

I, have B&C drivers 10HPL64 & DE 12-8.

Any sugestion about Box.

Something like on Att.

Thanks in advance.

Regards zeoN_Rider

 

[Variac]

col,

I was THIS close to ordering exactly that combo of the cheaper mylar driver with the Selenium adapter and the 10" "waveguide"


Now I'm sure that waveguide isn't optimal or correct by Earl Geddes' standards, but maybe the combo sounds pretty good anyway, Certainly you should do as he says and smooth the transition from driver to "waveguide" with some modeling clay if it isn't a perfect match or if there is a groove in the path. After that I think that setting the perimeter of the waveguide into rounded "lips" to smooth the transition from waveguide to baffle, would be a great idea.... Even 1-1/2" dia. would help a lot..

 

[Brett]

Re: Hi ti All!

I, have B&C drivers 10HPL64 & DE 12-8.

Any sugestion about Box.

Something like on Att.

Thanks in advance.

Regards zeoN_Rider

Work out the box dimensions and porting fo the 10 in Unibox or WinISD, then if you want a radial style horn, something like this might be OK.
http://www.geocities.jp/arai401204/Horn/A480FL/A480FL.html
http://www.geocities.jp/arai401204/Drawings/A480/A480.pdf

I've built the A290 and A300 in the past and they worked as he described. However, the DE16 seems a bit small and crossing it at 1k5, which is as low as I'd dare might be stretching both it and the 10.

 

[stoN_Cold]

Hi Brett!

All about horns is OK, I, like it woodcrafting bu Japanese!!

What about dimension for 10"?

I, am not close with Unibox or WinISD.

Sorry!

For crossover I'll use these on Att.

Regards zeoN_Rider

 

[Tenson]

Hi Guys,

Do any of you have an opinion of the combination of B&C DE250 with the B&C ME45 horn?

The response looks superbly flat, and there are few ripples in the impedance as far as I can see. See DE250 data sheet - http://www.jpleisure.co.uk/DE250.pdf

The ME45 horn is appealing to me because of its narrow height, which should allow it to be used in a MTM kind of arrangement.

Actually I don't have a use for it at the moment but I am getting kind of interested in good compression driver systems with all this talk of waveguides and stuff recently. The ME45 may be able to slip in to a project I am already working on and I could have a little play.

 

[col]

Hi Variac,

Yes, the price of the BC10, and Dayton WG with the Selenium adapter was so cheap I just had to give it a go. Even with shipping to Australia it is still cheaper than anything on offer over here.

I know this isn't going to be any where near as good as Earl Geddes designs but there is a fair bit I can learn from his posts while I attempt my bang4buck version 😉

I think a lot can be done with the transition of the compression driver and the waveguide. The WG and adapter has a thread coupling that adds 1" of tube inbetween the compression driver and where the conical shape of the waveguide begins.

I'm contemplating cutting off the threaded portion of both the waveguide and the adapter then working out a way of using some kind of epoxy resin to glue a piece of MDF onto the waveguide and then mounting/screwing the Selenium adapter (without the threaded bit) onto the MDF. This would bring the compression driver right up close to where the conical shape begins.

If it all goes pair shape I won't have damaged the driver and the WG and adapter only cost $15. So worth a shot.

col.