Coaxial Wedge Collaboration

R

Ron Kreiger

Freshman
Jan 11, 2011
46
0
0
63
Pennsylvania
www.s-o-t.com
Here's a little exercise where the community can participate in the development of a DIY Coaxial Wedge. I'll lay out the starting basic parameters. Through some discussion we can determine the final design criteria.

Starting Basic Design Parameters:
Intended Market:

  • JR Varsity/Weekend Warrior/Bar/Club/Church/Amusement Parks or Bands Carrying Their Own Pa. etc.
  • Must be of Coaxial Design 10'' model and 12'' model.
  • Must be constructed of wood
  • Must be capable of being built with basic power tools (table saw,drill press etc.) no CNC Router or machine work involving Lathes,Milling Machine, ETC. Basic shop tools most folks have in their garages or basements.
Open for discussion:

  • Budget
  • Driver and Component Choices
  • System Configuration ie: Bi-amp-able/Passive/Both
  • Response (freq./phase/group delay etc)
  • Output (efficiency/max output/power compression etc.)
  • Polar Response
  • Build Material (types of wood ,screws,glue,covering etc.)
  • Weight
  • Pack Space and Packing Geometry
  • Ergonomics
  • Aesthetics
We will try and do things from an orderly standpoint. In other words it's hard to determine driver and component choices without a budget. We can make budget adjustments as we proceed if there's compelling evidence to do so.

The final product will be on my coin and the design fully tested prior to be presented to the community. Of course feel free to build your own as we move along. Any design decisions will be posted as soon as they are approved.

Things completely off the table for discussion.

  • Rider Acceptability
  • Composite Builds

Feel free to contribute with suggestions and comments but most importantly why you are making your particular choices.

I am fully aware that different folks will have vastly differing opinions and all I ask is that all discussions that are presented with this collaboration are kept civil. Please keep it down to a dull roar!

Jeff Babcock will be moderating this topic and helping with the final decisions in the selections process. I would like to add a few more folks into that process as well, perhaps a panel of 5.

Anyone interested in being on the final selection panel please PM myself of Jeff Babcock.

Feel free to start throwing out some ideas.

Have a great day people!!!
 
Re: Coaxial Wedge Collaboration

I've been very happy with previous BMS drivers I have used. I would note however that a few people including Too Tall collaborated on a BMS based coaxial wedge a while ago. It would be nice to go a different route, so maybe avoiding BMS this time would be best. It was also noted that it took some work to minimize reflections on the backside of the horn with the BMS they used.

Regarding P-Audio, I have never used any of their drivers, but have heard reports of quality control sometimes being an issue. These are second hand reports though, so I don't know if there is any merit to that.

One driver that comes to mind is the B&C 12CXN76.

The 12CXN76 is around $450USD. Not inexpensive, but if we are looking for a very high quality offering with long term parts availability, this may be a good choice. It would give a good head start down this path. It's also lightweight. Is this too expensive for folks? I'm not opposed to less expensive choices but would like to put together something that is pretty darn good. Thoughts? Perhaps a couple of different driver choices, one in the price range of the B&C I mention, and another less expensive option? This may compromise box design optimization though.

Some other B&C options:
http://www.prosoundservice.com/Search_Results.html?m9:cat=/BRANDS/B%26C%20SPEAKERS/Coaxial

The RCF grant linked (CX12N351) might be nice too but is slightly more expensive than the B&C.

I also would like to vote for a low profile design, acknowledging the compromises that would be required for such a design.

Passive would be nice, but I'm happy with biamping.
 
Re: Coaxial Wedge Collaboration

coax -- does that necessarily mean compression driver ''through'' mid driver? or can it be a horn in front of a standard mid driver?

aka, a selenium on a conical waveguide, in front of a horn loaded mid?
 
Re: Coaxial Wedge Collaboration

I hadn't thought of the ''loaded coaxially'' approach, good point. While this might be feasible, driver depth might make it more challenging to produce something compact. It's something to consider. Such an approach would expand the choice of available drivers considerably should the depth be manageable.
 
Re: Coaxial Wedge Collaboration

All possibilities are open Jim. As of now we haven't determined the box type or configuration. Basically that's why this is a collaboration.

All horn loaded is fine as long as we agree on the size and geometry of the final product.

Right now it's an information and ideas gathering agenda. If say we decide on reflex then we might start an all horn loaded wedge collaboration down the road.

If you have more to add regarding an all horn loaded solution by all means throw it out there.

All items presented ''will'' be objectively discussed.
 
Re: Coaxial Wedge Collaboration

http://www.akiplab.com/pics/drivers/PA108/PA108.html

plus this:

  • I hate monitors that sound like @#$@# because they are supposed to.
  • I am a baritone, and I sometimes sing with a bass singer that can almost bottom a piano.
  • A monitor should be capable of flat from 80hz on up for male vocalists, and should sound good... actually it should sound REAL good...
  • I think this is one way to get there.
 
Re: Coaxial Wedge Collaboration

Hi Jim,

That ribbon looks very interesting, though it may not have enough output for some applications based on the reported sensitivity and power handling (102db and 60W Prog). If there is some documentation that shows its' power handling according to frequency, that might be helpful, as I'd expect the suggested 1K HPF is likely to be the limiting factor.

What is parts availability like for this manufacturer, and what sort of product support lifetime is this unit likely to have?

One other concern is water and other foreign substances.... in a wedge format with the driver angled towards the sky this is more prone to abuse than a ribbon in a mains cabinet. Are these likely to die if they get wet?

Cheers
Jeff
 
Re: Coaxial Wedge Collaboration

I'm guessing that a beer poured in a ribbon is the same result as beer poured in a compression driver.... point well taken.

I'll ask jeff at traxav some of these questions on power handling, etc, as he imports them from taiwan. (although the ribbon at 60/135 @1khz cross compares favorably with a selenium 220ti at 80/160@2khz)

I'm sure other HF options would be equally at home in front of this hornloaded mid. Some selenium and B&C options come to mind. The particular mid/horn that I posted hornresp for needs something that can meet at 1.2khz or even slightly lower.

I know from my perspective, I HATE most monitors that I come across. I've even taken to putting 2'' thick oak wedges on studio monitors and adding a grill for my small church monitor needs.... At least then I have a reasonable sounding monitor.

This collaboration just seemed like a perfect excuse to actually dive in an build the 'perfect' sounding monitor -- and the ribbon came to mind.
 
Re: Coaxial Wedge Collaboration

Jeff Babcock wrote on Tue said:
I've been very happy with previous BMS drivers I have used. I would note however that a few people including Too Tall collaborated on a BMS based coaxial wedge a while ago. It would be nice to go a different route, so maybe avoiding BMS this time would be best. It was also noted that it took some work to minimize reflections on the backside of the horn with the BMS they used.
Click to expand...

Thanks for the consideration on the BMS coaxial wedge monitor possibility. The B&C products are very nice too, I used them before the HAL BMS project.

I will be at the Midwest Pro Audio Lovefest in Merriville with one.

Don't forget the Eminence coaxials-you can pick a different brand of HF driver to screw on if desired.

Best regards,

John
 
Re: Coaxial Wedge Collaboration

There are several high output , high SPL Planar Ribbons available in the marketplace.

The Stageacompany one comes to mind first that is readily available as a single priced unit.

http://www.stageaccompany.com/en/products/ribboncd.php

It is pricey however.

Also SLS has some but I'm not sure if you can buy them as individual components.

http://www.nczon.com/Planar%20Ribbon%20Technology.htm

Alcons has them as well but again the price is fairly high and I am pretty sure you can only source them as an OEM and not by individual pieces but I am not 100% certain of that.

http://www.alconsaudio.com/site/technology.html

Piega a company out of Switzerland has shown a bunch of press a few years back when they started making their own and using them and if I remember theirs came in at around 111db/2.83V/1m and they needed to seriously pad them down for their applications.

Page through the .pdf and you'll find some cool reading regarding the actual development and assembly of a Planar Ribbon.Piega actually hand assembles them!

http://www.piega.ch/download/Piega_Praesentation_E_2010.pdf

The trick to making a ribbon high power is being able to laminate the Kapton HN like .005'' film with thin aluminum foil around .007'' and then etch the voice coil accurately.Basically when finished it looks very similar to a flexible type circuit heater that would be used in a spacecraft or aircraft except the copper coil is replaced with an aluminum one.

It's cool technology but the materials and manufacturing process keeps it rather expensive, otherwise I think a lot of manufacturers would have already been making them.(strictly speaking of the high output/high power handling types) Home stereo units are a dime a dozen.
 
Re: Coaxial Wedge Collaboration

Quote: said:
The trick to making a ribbon high power is being able to laminate the Kapton HN like .005'' film with thin aluminum foil around .007'' and then etch the voice coil accurately.
Click to expand...



Those ( lamination and etching ) have been issues for a while.

( What about lasers? )
 
Re: Coaxial Wedge Collaboration

Alcons makes some tremendously good stuff, but unfortunately the price reflects this. The SA one is also listed as $579 Euros. Yikes. I'm not sure many here will want to spend more than $1000 in materials for a DIY wedge.

Whatever is decided upon for drivers, I think it is important to ensure that the product will be well supported. This is one reason I mentioned B&C earlier, they have an excellent reputation for long term support of a product.

There is nothing worse than ending up with something you can't get replacement parts for a few years down the road.

That said, use of a ribbon would add something unique to this project. So it's certainly worth further discussion if a suitably high output and cost effective option is out there with a reliable/stable production source.

Great input so far folks.
 
Re: Coaxial Wedge Collaboration

Laser etching is possible I'm sure.Setup would probably be costly however and with any heat oriented process laser/plasma etc. you run the risk of substrate damage.

Not sure if sputter etching is possible, however as my last encounter with sputtering a substrate is it could only reach a few microns in thickness and that would not satisfy the higher current capability needed to produce a higher efficiency product.

Technology changes however so perhaps sputter/etching has evolved as well.Someone closer to those fields of expertise would know better then I.
 
Re: Coaxial Wedge Collaboration

well regardless of the HF, Ron -- what did you think of the hornresp? pretty stout to 80hz in my opinion.

Is that a good base to work up a HF section for? or should I try again?
 
Re: Coaxial Wedge Collaboration

Jim,

I got a little behind the curve today so I still haven't run the numbers. Hopefully I get to it within the next few hours.

As soon as I do I'll post the results as I'm sure a few would like to see them.

Hey BTW which driver is that you modeled with.It appears to be of a rather low efficiency for a horn load when I switched the output to 2.83V. I'll post the charts in a few.

For future reference to anyone posting response charts such as those from Akabak or Horn Response could you please list the driver/drivers you used for the modeling.
 
Re: Coaxial Wedge Collaboration

OK here's the Horn response Charts as promised.



Input Power is 50 volts results are @ that voltage.



Panther206.jpg


Panther208.jpg


Panther209.jpg


Panther210.jpg


Panther211.jpg


Panther212.jpg


Panther213.jpg


Panther214.jpg


Panther215.jpg


Modeled SPL Horn and Port combination calculated with horn mouth and port exit in the same plane.

Combined output changes if you move the port exit forward or rearwards on the horns mouth.

Panther216.jpg




Anyone wishing to convert into an Akabak Script feel free to do so.
 
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