Coaxial Wedge Collaboration

[Rick Powell]

Re: Probably time I contributed

Gents,

Now that my name has been tossed around a few times due to the design I developed and posted on the old ProSoundWeb forum a few years ago, its probably time for me to add my thoughts to this design effort.

What I learned from the experience of designing and building 4 wedges that I still think are very good performers and get stinking loud, is that I wouldn't do it again. Here is why.

(snip - long discussion on return on investment, etc.)

Ciao
Simon

Simon,

Thanks for your thoughts. A few caveats here, based on your situation:

1. Your total costs were about $8k or $2k per monitor, including Radian speakers, passive xover, wood, hardware, finish, and Speakerpower module (module would probably be half the cost of the unit). Speakerpower will not sell in small lots anymore, IIRC, so if someone wanted to adapt this to a powered situation, it would likely need to be a group buy. Am I correct that your investment would have been closer to $1k per monitor, unpowered? Also, you bought a biamp module but were happier with the sound when using the Radian passive xover. I am assuming you would go with the cheaper mono Speakerpower block if you had to do it again?

2. Were your costs higher for the components due to shipping to Europe, VAT, etc. than you would incur if located in the US?

3. I agree that price rather than quality will be the determining factor for hired sound, and most will settle for 80% of the quality at 1/2 the price at the Junior Varsity level.

Thank you for your input. I still have your design saved in my files.

FWIW, there are so many "powered speaker" monitor duty - pole mount mid/hi capable speakers now (like QSC 122/K12 and Ev Zxa5) that building your own is a DIY option for personal enjoyment or preference, rather than a necessity. This was not the case 10 years ago.

 

[Simon Coffin]

Re: Probably time I contributed

Am I correct that your investment would have been closer to $1k per monitor, unpowered? Also, you bought a biamp module but were happier with the sound when using the Radian passive xover. I am assuming you would go with the cheaper mono Speakerpower block if you had to do it again?

2. Were your costs higher for the components due to shipping to Europe, VAT, etc. than you would incur if located in the US?

3. I agree that price rather than quality will be the determining factor for hired sound, and most will settle for 80% of the quality at 1/2 the price at the Junior Varsity level.

Hey Rick,

If I remember right, the $2000 figure per speaker also includes a case since the wedges do not stack easily. But otherwise yes, just under $1000 passive is a safe ballpark.

Given the option to do it all over again, I wouldn't go powered. While a powered solution has many benefits and certainly the SpeakerPower amp modules are first rate, my mantra of keeping inventory low and usage high has steered me to external amps since I can use the same amp rack and DSP for almost every show I do. One could probably argue that an active subwoofer makes sense since we tend to have fewer of them, at least compared to the number of wedges and tops, and the Inventory/Usage ratio remains the same if I have 4 channels of amp in a case or 4 channels of active modules.

Yes, I do have the biamp SpeakerPower amps, and have since installed the Radian Audio passive crossover. Probably if I had better Smaart chops, I would have been able to tune the internal DSP in the amp modules. But given my abilities, the passive crossover was the better solution.

Shipping to Europe is not bad since I have an APO address.

Part of my thinking about the Coax project is to come up with something different, not necessarily groundbreaking, but something that combines several good ideas in a manner that nobody else does. Leave the groundbreaking stuff to the likes of Tom Danley and his peers. Give me handles that are easy to grasp and placed at the CG, a compact cabinet that saves space on stage and in storage, sound quality comparable to a Qrx or Srx, clever cable routing for a clean stage, a robust grill, the ability to be used in several configurations and a well developed passive crossover or DSP settings. To my mind at least, that would make for a really useful speaker.

Ciao
Simon

 

[Ivan Beaver]

Re: Probably time I contributed

Yes, I do have the biamp SpeakerPower amps, and have since installed the Radian Audio passive crossover. Probably if I had better Smaart chops, I would have been able to tune the internal DSP in the amp modules.

Have you actually TRIED to do any work in the DSP of the Speakerpower amps?

It is NOT as easy as you amy think-especially making an EQ change. For example if you want to change 1 filter 1dB it takes about 20 keystrokes to be able to see the change in the measurement.

OOPS you also need to change the freq a tad-another 20 or so keystrokes.

Eqing is best done with an external unit (a Behringer 2496 works well-other not so well) and then the numbers crunched (you cannot enter Q or bandwidth, you have to enter the width of the filter in Hz-so a 1/2 filter at 100Hz is totally different than a 1/2 octave at 4Khz), and then enter them into the eq software and then open that with the DSP.

I have spent waaayyyy more hours than I would have liked to, programming the DSP on those units.

 

[Simon Coffin]

Re: Coaxial Wedge Collaboration

Have you actually TRIED to do any work in the DSP of the Speakerpower amps?

It is NOT as easy as you may think-especially making an EQ change. For example if you want to change 1 filter 1dB it takes about 20 keystrokes to be able to see the change in the measurement.

Hey Ivan,

Yes, I spent many months fiddling with the DSP config on the SpeakerPower modules and learned to dislike it. Making any change was less than easy, but in fairness it wasn't designed for the average user in the first place, so I could hardly complain.

Ciao
Simon

 

[Kimo Lewis]

Re: Coaxial Wedge Collaboration

Hold on here... It appears Bennett has put words in my mouth... Let's restate exactly what was said.

The driver is everything.

I would assume you are also considering the design of the passive crossover in this statement?

If you do not believe that driver selection is paramount I don't really know what to say. A good sounding and well behaved driver makes the box. A good crossover simply attempts to optimize that driver and make it shine.

I never said I "do not believe that drive selection is paramount". What I said was the passive crossover has to be considered "also".

To over state and over simplify speaker components is simply not accurate. And yes Bennett, you did over simplify by saying, "The driver is everything". If this were so, then it would be easy for the DIY world to make a "well behaved" coax wedge. I don't see anyone putting forth any ideas yet, so it must be harder than simply picking "well behaved driver" and putting it in a wedge shaped box. The fact is, it is not a simple matter to design a good crossover. It is difficult to have a "well behaved" system without considering all aspects of the speaker system. And you certainly can not have "well behaved" systems without measuring the whole of the speaker system, otherwise, how would you know if it was "well behaved"? Then you need to redesign with measured data in mind, and reiterate the process, especially for a active or passive crossover, something I stated in my very first post.

One driver may be "well behaved" in bass reflex box, but could be completely unstable in a bass horn. One compression driver could measure and sound "good" on one horn and the opposite could be true with the same driver on a different horn. In fact, I have polar measurements of this very thing, one driver on two different horns are not the same.

I don't even know what you mean by "well behaved". Is that some marketing jargon?

Here are 9 drivers, please tell me which ones are "well behaved" and why.
http://www.eminence.com/speakers/speaker-detail/?model=Delta_12LFA
http://profesional.beyma.com/pdf/12G40E.pdf
http://bmsspeakers.com/cone-speaker...-cone-driver/12n620-cone-driver-introduction/
http://www.eminence.com/speakers/speaker-detail/?model=Beta_12CX
http://bmsspeakers.com/cone-speaker...-transducer/12cn680-coaxial-transducer-intro/
http://profesional.beyma.com/ingles/pdf/12KX.pdf
http://profesional.beyma.com/ingles/pdf/CP350Ti.pdf
http://www.eminence.com/speakers/driver-detail/?model=PSD2002
http://bmsspeakers.com/cone-speaker...ression-driver/4552nd-hf-driver-introduction/

Case in point, attached are some measurements of a prototype coax of my own design with a 6.5" woofer and a tweeter mounted in front of the woofer. I started this project last December to see if I could figure out a coax "hot spot" and possibly a small line array.

All things are equal except the crossover. One graph shows the on axis response of:

- active biamped 12 db/oct BW crossover with two notch filters,
- passive crossover with two pole low pass at 1500 hz and two pole high pass at 2000 hz and two notch filters
- active biamped 12 db/oct LR crossover with two notch filters.

I have also included the polar responses and THD of the two active biamped crossovers and notch filters. There is a striking difference with the polar responses and the sound of the two crossovers are very different. Once again, the only change to the complete system was the crossover, and to hear the two systems, you wouldn't guess they were the same speakers in the same box.

 

[Jeff Babcock]

Re: Coaxial Wedge Collaboration

I don't see anyone putting forth any ideas yet, so it must be harder than simply picking "well behaved driver" and putting it in a wedge shaped box.

There are ideas in place. One of our members who has been helping to drive this project unfortunately experienced some fairly significant data loss so things have been somewhat stalled for the last while. That will change soon and more will appear in the near future.

 

[Jack Arnott]

Re: Coaxial Wedge Collaboration

Hello All,
Price on the BMS has just gone up 25%. (more or less)

Invest in neodymium now.

Regards, Jack

 

[Ron Kreiger]

Re: Coaxial Wedge Collaboration

Jeff thanx for running some interference.Unfortunately I did in fact suffer near complete data loss due to a failing power supply that wiped out both my HDDs one with the back-up data. Was running a RAID 1 (mirror image) and lost both drives at the same time.Bad part was it happened in the middle of Tax season and yeah all my Tax data was lost as well. Soooo the scramble ensued to complete everything by April 18th which I managed. Now back to the drawing board! LOL.

Jeff sent me this big ass lead ball with a nice ankle bracelet but for some reason he neglected to send me the key!

Look for basic box designs by mid week next week so you guys can start firing off suggestions as to ways to better the box, change the box or simply throw it in the dumpster and start over! I'm fairly thick skinned so feel free to fire away.

Regarding driver choice I thought that was already a done deal? Yes ? No? If yes please take a moment and look at the charts that are stored here.I did spend quite a bit of time crunching the numbers and tweaking to get what I thought was a fairly decent predicted response while maintaining the drivers power handling and bass extension without hitting x-max.Last thing I would want to see is the box fail because the passive or active crossover is getting in the way.

I can do passive design but I'll be the first to admit that it isn't my strong point and would be happy to pass on that baton to the next runner! Same with measuring and active set points.

@ Kimo I PM'd you back.

@ Jack Completely off topic. Do you have any BMS 4540ND diaphragms in stock? I need 2. @ Jack again. I've had some rare earth ETFs but they were kinda cyclic and kept hitting my stops and pushing me out.They've done OK but Silver was a big winner for me for the past two years.Gold did well too but the volatility the early part of January/Feb. this year pushed many out and allowed the shorts to cover.Buy the dips!

 

[Jack Arnott]

Re: Coaxial Wedge Collaboration

Hi Ron, I do have the diaphragms.
What I meant was, if you are going with the B&C buy it now. It will be going up if it hasn't already. Neo has gone up by factors over the last year.

Regards, Jack

 

[Kimo Lewis]

source for B&C 12CXN76

I googled but couldn't find a location to buy a single B&C 12CXN76 in the USA.... any ideas?

 

[Philip LaDue]

Re: source for B&C 12CXN76

I googled but couldn't find a location to buy a single B&C 12CXN76 in the USA.... any ideas?

Pro Sound Service in Braintree, MA.
http://www.prosoundservice.com/m9/BC-12CXN76--b-c-12cxn76-12-coaxial.html

 

[Kimo Lewis]

Re: source for B&C 12CXN76

Thanks...

 

[Kimo Lewis]

FBT Verve 12m

Does anyone know for sure that the FBT Verve 12m or 12ma uses exactly the B&C 12CXN76? Or does the box contain a B&C OEM version of a coax driver?

Does anyone have measurements for either box? I'm not looking for manufacturer's specks, but their own unbiased measurements.

 

[Kimo Lewis]

Re: FBT Verve 12m

Just as a frame of reference, here are the manufacturer's specs for the FBT Verve 12m which uses some kind of B&C coax driver:

www.fbtusa.net/files/Verve_12m_Polar_patterns.pdf
www.fbtusa.net/FBTVerve12mmonitortc.html

As you can see, the polars get very narrow at 2000 hz, and appears to be the same at 2000 hz as it does at 16000 hz. This also appears to be at the crossover region which is stated to be at 1.8k hz. The Q factor shows a very narrow pattern at crossover. My hope is we can do better at 2000 hz. But the narrowing at 2000 hz may be a result of the woofer and tweeter interaction and not the crossover. Who knows?

The amplitude response looks very respectable at plus or minus 2.5 db. We would be very lucky to have the same amplitude response.

The problem with all these measurements is the manufacture did not state how much smoothing was applied.

 

[Jeff Babcock]

Re: FBT Verve 12m

Does anyone know for sure that the FBT Verve 12m or 12ma uses exactly the B&C 12CXN76? Or does the box contain a B&C OEM version of a coax driver?

Does anyone have measurements for either box? I'm not looking for manufacturer's specks, but their own unbiased measurements.

Hi Kimo,

No, the FBT does not appear to use the 12CXN76 or for that matter be very similar.

Their product page says it is a custom driver.

FBT is crossing at 1.8K, whereas B&C recommends 1.2K for the 12CXN76.

The coverage pattern of the FBT is 90deg conical , whereas the 12CXN76 is 80deg

FBT rates their box at 300W RMS, the 12CXN76 is a 350W RMS driver.

Based on these specification differences I believe the 12CXN76 should be a better driver.

 

[Grant Conklin]

Re: FBT Verve 12m

Does anyone know for sure that the FBT Verve 12m or 12ma uses exactly the B&C 12CXN76? Or does the box contain a B&C OEM version of a coax driver?

Does anyone have measurements for either box? I'm not looking for manufacturer's specks, but their own unbiased measurements.

I think the 12CXN76 more closely resembles the driver used in the now discontinued PSR 212 M. I happen to have one (PSR 212m) in perfect condition for sale.

The Verve 12m definitely uses "recone kit R12CXT for CXT."

If the Verve 12m does not use the 12cxt, it very closely resembles it. http://www.prosoundservice.com/57.html?m9:search[group]=273439;search[nested]=1;search[fuzzy_sku]=1
If it's crucial to the mission I can open mine up and compare.

 

[Jeff Babcock]

Re: FBT Verve 12m

Just a quick update for those who may be wondering about this project. It's not dead, but is in a bit of a holding pattern right now unless someone else has the time to run with it. Ron is basically booked solid until September and my free time for this is extremely limited as well over the summer.

We are essentially at the point of coming up with a physical design (dimensions, look & feel etc) for the enclosure along with some prototypes, based on the box volume and specs which Ron has already done some modeling for - box volume 1.52Cu. Ft with port length determined by choice of either the B&C driver (my personal preference), or the Ciare driver (which looks good but may be harder to source in North America)

Some ideas which have been discussed:
- dual angle wedge vs single angle with adjustable feet
- low profile
- as light as possible
- pole mountable if possible
- consideration for NL4 input placement

Feel free to share thoughts. Perhaps we can make the goal to come up with some rough visuals over the summer and begin building some prototypes in the fall.

 

[Ron Kimball]

Re: Coaxial Wedge Collaboration

Not exactly DIY but I've commissioned Ramsdell Pro Audio to design and build me eight coaxials based on the Eminence 10CX. They will be 30/60 degree dual angle of minimal cabinet dimensions - two will stack together to form a 13.25" cube and fit in a supplied tray to make the pack stable. I'll be able to fit them two cubes high in my hatchback and they'll be part of my TH-Mini's plus RCF 310A's rig. Here's a rough prototype he built to make sure everything can still fit:

They'll be somewhere around $300 each and will have a fairly sophisticated passive crossover to maximize GBF. He already has a 10CX design but it is optimized for low end and the HF driver he uses is no longer available so he has to retune the crossover for a new one - for this design he's chosen a lower profile one to minimize the depth of the cabs, there will only be 1/8" of space under the HF driver! Each cab will only have about 475 cu in of airspace so will roll off at 150HZ or so. I'll tweak the EQ on the studiolive to get that a bit lower - shouldn't be any real problem to get the virtual f3 down to 100 (or even 80?) as sealed cabs only roll off at 6db/oct.

 

[Michael John]

Re: Coaxial Wedge Collaboration

Hi All,

I've been reading this discussion with keen interest for sometime. (I hope it picks up again soon.)

In the meantime I just purchased a BMS 12CN680 and crossover from Jack - it's in transit - and I've designed a cabinet in the style of a 12AM but with a 45 degree front face. It's ported, has a volume of about 24L (0.9 cubic feet) and 3 cabinets can be made from a 8'x4' (2400x1200mm) of 18mm ply. I hope to post the CAD design shortly.

I'm hoping to switch this between passive and biamped. I have SysTune, Lake processors and some idea of how to created a biamped DSP setup but I'd appreciate any advice. Bennet?

Cheers,
Michael

 

[Bennett Prescott]

Re: Coaxial Wedge Collaboration

I'm hoping to switch this between passive and biamped. I have SysTune, Lake processors and some idea of how to created a biamped DSP setup but I'd appreciate any advice. Bennet?

I'm not sure it's possible to teach someone to build a good loudspeaker preset over the Internet. It requires a good grounding in several audio disciplines, and ideally several days of listening and tuning. Phil and I were talking about teaching a course on this, but the question is: is it relevant to anyone any more? I make good money retuning older PAs and creating presets for people's boxes that are either custom or that don't have manufacturer presets available. It seems, however, that these are the only applications for which these skills matter any more. The vast majority of the industry just uses a well supported design, or a powered design.