[James Lehman]

Yes! I believe there are still some new speaker design ideas that have not been done to death!

http://akrobiz.com/speakers/black_trumpets

I had this idea floating around in my head for years before I actually made these.

I started on these and got side tracked with my tri-amped line source array.

http://www.audiocircle.com/index.php?topic=110552.0

The baffles are 6 solid layers of MDF. The ports are nothing but holes through the MDF.

The resonators are 7 cu. ft. tuned to about 20Hz for a -3dB of about 17Hz.

The woofers are the same as in my line array system, MCM 55-1190.

I removed the dust caps and added phase plugs.

As you can see, they are in a rather unique isobaric arrangement.

Currently they are driven by a pair of Carver power amps for the woofers and an AMP-3 kit from 41Hz.com for the horns.

I'm using a Behringer 2 way active crossover, but I might use a 3 way crossover and mix the low and the mid back together before feeding it to the woofer amp. That way I could control the baffle step.

The other speaker you see in the photos is of the set "Metal" which has a website but it cannot be linked here.

James. 

[Letitroll98]

Hey James.  Help a poor, befuddled facilitator out here.  Reading your posts and website, I can't really determine if you're an enthusiastic hobbyist offering open source designs, or a speaker building consultant selling your services.  I think what I'm seeing is the former, with your "day job" being the computer consulting company.  But then I'm seeing the Metal webpage with this text, "To inquire about purchasing Metal or to have a custom sound system designed and built for your home, contact James at james@a******.com"  Could you be so kind as to clear up your role as an industry participant either here or in a PM to me?

FYI, here's the link to the guidelines regarding industry participants and AC: http://www.audiocircle.com/index.php?action=about;area=industry-members
 

[James Lehman]

I get it. I make awesome speakers. I have made some. I'm not selling speakers. I'm selling know-how. My own. And that's a matter of getting to know me.

I have not offered anything for sale. I have offered ideas for free.

Look at http://speakerbuilding.com and look up the Extra Stimulus Twin Iso 8. It's been there since Feb. 96.

In all seriousness, what's the big deal anyway?

[Letitroll98]

I get it. I make awesome speakers. I have made some. I'm not selling speakers. I'm selling know-how. My own. And that's a matter of getting to know me.

I have not offered anything for sale. I have offered ideas for free.

Look at http://speakerbuilding.com and look up the Extra Stimulus Twin Iso 8. It's been there since Feb. 96.

In all seriousness, what's the big deal anyway?

OK, here's the big deal anyway.  Audio Circle is a website funded, among other things, by Site Sponsors (manufacturers) who pay for their own circles in which they discuss, promote, and advertise their products.  If manufacturers were allowed to post freely in the community circles why would they pay for a circle, and secondly, when industry participants who don't sponsor a circle promote their products for free, it generally pisses off the Site Sponsors.

So, are you an industry member?  From the About/Help section you haven't yet read:

"This is the definition we use:

An industry member is someone who makes a significant portion of their income from an audio-related business, or who uses this site to promote audio-related services or products from which they derive income.

For example, someone who makes audio widgets and has a website listing products and prices is assumed to be an industry member. So is someone who consults as a designer of amplifiers or speakers.  However, a hobbyist who does the occasional mod or build (for example) and receives payment for it is considered to be a regular member, not an industry member. If that person were to start using this site to promote those services, then we would consider them an industry member."

Does this apply to you?  From your website:

"For the complete set, that already exists, that is the obvious feature of this Website, consisting of four standing columns, a center channel, two sub woofers with glass tops, an active sub woofer crossover and power supply, $10,000 US.

A stereo pair of columns similar to those that are a part of the above set would be between $3,200 and $3,600 US, depending on the finish. A single center channel would be half of this price.

A matching pair of sub woofers for the above mentioned stereo pair would be about $2,200 to $4,000 depending on the finish, the number of woofers used and the complexity of the design. A single sub woofer would be half of this price. The price of sub woofers would include an active crossover with a power supply."   

I think this pretty much says it, you're selling stuff.  However it's obvious that it's a new venture somewhat informally set up, you say quite clearly this is a prototype build, it appears you've sold a pair.  Additionally you're also a hobbyist who has built some kewl designs for your own use and have posted plans and builds in the public domain.  So if you insist on linking your commercial site you have to follow these guidelines:

"Disclosure

As with most sites of this nature, we require that industry members disclose that fact. Here, industry members do so by joining one of the groups set up specifically for industry members. The groups are:

Industry Participant
An industry member who does not support the site as an associate or sponsor. For more information, see Industry Participant.
Industry Associate
An industry member who helps to support the site and has full access to the Commercial Zone. For more information, see Industry Associate.
Site Sponsor
An industry member who supports the site by sponsoring it, and has their own circle for discussing products. For more information, see Site Sponsor.
Your group membership will be shown under your username anywhere that you post.

Posting rules for industry members

All of the Posting Guidelines apply to industry members. We encourage you to participate freely in all areas of the site, in topics that do not discuss your products or services.

For topics concerning your products and services, please remember that the community circles are designated "non-commercial." While we understand that you will wish to continue a discussion about your products if one starts in a community circle, please limit your responses to technical information about the product, and then only in response to a specific member query.

For all other discussion related to your product, such as product availability and pricing, future product features, or anything related to your business activities, please move the discussion to one of the areas specifically designated for commercial activity, as appropriate:

Sponsored Circles
Commercial Zone
Industry Ads"

However, a big however here, if you will remove your links and references to the commercial portion of your business, the Metal page and the Speaker Consulting pages, I'm happy with considering you a hobbyist free to post anything within normal site guidelines (which basically say act like a human and don't be a jerk, pretty easy for most of us around here) about your personal speaker builds that are public domain like the "Extra Stimulus Twin Iso 8" and "innovative bi-amped point source".  I assume a computer consultant can operate the "Modify" button on your past posts, but please ask if you want me to do it for you (I don't mess with peoples posts without express permission, it's against AC policy and downright rude anyway).

So the "big deal" is really up to you.  I really like your personal and public domain designs and I think they fit perfectly within the spirit and focus of the Enclosures circle.  I really want to consider you as a regular member here, at least for now, if your speaker business takes off we may have to revisit this.  But you simply must separate any commercial references from your normal posts.  I hope I've been clear and if you have any questions please feel free to ask.

[James Lehman]

No. I do not make any income from speakers.

I made the website "Metal" more than 12 years ago!

It's gotten more attention in the past day than it has in the previous 12 years.

I know I came out-of-the-blue, but I have been putting stuff on the web since 1996.

[Davey]

Point source??

Dave.

[James Lehman]

Yes. As opposed to line source array. "Black Trumpets" are point source radiators.

[richidoo]

Very artistic, both designs. Congrats James

[James Lehman]

Thank you!

I think of speaker design as an art.

I think of speakers as musical instruments.

[Letitroll98]

I made the website "Metal" more than 12 years ago!

It's gotten more attention in the past day than it has in the previous 12 years.

Ha!  That's great.  At least we have some sort of impact around here.  "Feel the power of the Circle young Skywalker"

Thanks for getting rid of the links.  Looking forward to your posts.

I know I came out-of-the-blue, but I have been putting stuff on the web since 1996.

I'm pretty sure I've seen your posts around.  Not sure where as I don't surf the audio sites too much anymore.

Yes, you're absolutely correct, speaker design is an art, with math and electronics as it's paint and canvas.

[James Lehman]

Glad we're back on the right track.

I really had no intention of upsetting anyone.

As for the art of all of this.... did you see my polymer clay work listed here:
http://www.audiocircle.com/index.php?topic=110576.0

I'm also very well known for my work in the field of color laser projection.
http://www.audiocircle.com/index.php?topic=110528.0

I am a self published recording artist

And I paint too!

[Letitroll98]

Very pretty, General. Very pretty. But, can they fight?

[doug s.]

Glad we're back on the right track.

I really had no intention of upsetting anyone.

As for the art of all of this.... did you see my polymer clay work listed here:
http://www.audiocircle.com/index.php?topic=110576.0

I'm also very well known for my work in the field of color laser projection.
http://www.audiocircle.com/index.php?topic=110528.0

I am a self published recording artist

And I paint too!

ok, i really don't wanna be a stick in the mud.  but, in your clay polymer thread, you link this site:
http://akrobiz.com/pc/

from there, you can get to here and here:
http://www.akrobiz.com/speakers/index.htm
http://www.akrobiz.com/speakers/metal_index.html

as long as the speaker site is linked to you, and to your posts and the websites you post, i think it's a problem, per the info quoted by letitroll from that site.  i will shut up now...   

doug s.

[James Lehman]

ok, i really don't wanna be a stick in the mud.  but, in your clay polymer thread, you link this site:
http://akrobiz.com/pc/

from there, you can get to here and here:
http://www.akrobiz.com/speakers/index.htm
http://www.akrobiz.com/speakers/metal_index.html

as long as the speaker site is linked to you, and to your posts and the websites you post, i think it's a problem, per the info quoted by letitroll from that site.  i will shut up now...   

doug s.

I made a really nice spice cabinet for my kitchen this summer.

I'm not selling that either.

Uh.... has it occurred to anyone but me that the "offensive material" from my website has been copied and plastered right here were everyone can read it without having to follow any links at all? 

And now you have posted the very same URL that I was asked to remove! 

James. 

[MaxCast]

Hi James,
thanks for your understanding through all this.  Letitroll98 has the tough job of deciphering our industry participants guideline.
Besides funding, AudioCircle was started with actual real life manufacturers posting about their products.  You could actually talk to the designer of a speaker or amp, etc.  They have their own circle to discuss anything and everything about their products.  In the general circles we don't allow any advertising or promotion by industry participants.  Answering questions about your own product is fine.  This gives regular members an area and feeling where we can talk about audio without sales pitches.

Letitroll98, it is your call.  Since it is not primary income I think it can stay.  Just let-it-roll and see where it goes 
Maybe there is something to be learned or tried from James' projects.  Just remember it can be moved to the commercial area for speakers at any time.

[Letitroll98]

It's unfortunate and onerous, however much needed, that the discussion has moved far away from the title of the OP.  James has some baggage that followed him here from a long neglected website, and I'm fine with taking him at his word that this is the case.  He's agreed to that part of his website being taboo as far as linking and referencing.  Unless something new comes to light, that's my final word.

Now hopefully we can get back to bi-amp point source.  Okay, please detail the isobaric section.  I can't see the other woofers in the pics.  I like the laminated MDF panel, should be solid as a rock with an easy way to create cavities for loading, but I don't immediately see how it works.  Secondly, why the horn loading?  Not that it's wrong or anything, just what made you go with a horn for this application.  I can imagine additional questions as I haven't seen anything like this, but we'll go with these for now. 

[doug s.]

I made a really nice spice cabinet for my kitchen this summer.

I'm not selling that either.

Uh.... has it occurred to anyone but me that the "offensive material" from my website has been copied and plastered right here were everyone can read it without having to follow any links at all? 

And now you have posted the very same URL that I was asked to remove! 

James. 

since this is not a spice cabinet forum, it wouldn't make a difference if you were selling 'em.  but, unless your website isn't accurate, you are selling speakers and custom speaker design.  even if it isn't your main source of income.

don't get me wrong - i find your actual substantive posts extremely interesting, and i don't want you leaving a/c.  but, is it really that difficult to divulge your interest in your avatar and/or signature?

and i don't think there's anything wrong w/your info being publicized - in fact, that's the whole point, imo - i think people should know your status.  it is awful hard to be totally impartial about something when you have something at stake, even if it's not "full time"...  just ask ajinfla.  the issue about whether or not you have to contribute financially to the site is secondary, imo, to the one that folks should have full disclosure about your "hobby" when reading your posts.

doug s.

[doug s.]

Since it is not primary income I think it can stay.

does this mean ajinfla can go back to being a non-mfr participant?  just sayin'...

doug s.

[Letitroll98]

It's unfortunate and onerous, however much needed, that the discussion has moved far away from the title of the OP.  James has some baggage that followed him here from a long neglected website, and I'm fine with taking him at his word that this is the case.  He's agreed to that part of his website being taboo as far as linking and referencing. Unless something new comes to light, that's my final word.

[James Lehman]

It took me quite a while to visualize in 3D how the laminated MDF would work. I also wanted to fit all of it into pieces that could be cut from one sheet of material. That's always a factor in my cabinet designs; how to use whole sheets of MDF or veneered plywood and get the most out of it, while still achieving the proper volume, etc...

... http://akrobiz.com/speakers/black_trumpets ...

Then I had to figure out a system to hold it together in such a way that it could be taken apart if the drivers ever needed to be replaced.

The woofers are back to back, but they are shifted a bit side to side so that the baskets and magnets are meshed together as close as possible. This puts the front and back planes of the woofers as close together as possible and the laminated baffle is as thin as it can be. (Does that make sense?)

I used the horn and driver because I wanted something that could go lower than a typical tweeter. I also liked it because of the low 2nd and 3rd harmonic distortion and very high SPL. This one is supposed to do 700Hz to >20KHz within 6dB and is about 106dB @ 1W @1M.

The horn came with a square flange and mounting hols on the outer rim. I cut that off and ground it down smooth. The voice coils of the horn driver and the front woofers are in the same plane.

The bolts I used for the electrical terminals with the washers and nuts cost me over $100! They are a special allow of Copper that is much harder and actually has slightly less resistance than pure Copper.

The woofers are in series parallel both electrically and PHYSICALLY. The idea is that isobaric coupling one pair of woofers cuts the cabinet volume in half and using two isobaric units doubles it. So 4 woofers take the cabinet volume of just one. You get twice the cone area, 4 times the power handling and you get a symmetrical moving mechanism that has much less even order harmonics.

The one thing that gave me confidence that I could make this work is the fact that since about 1997 or so, I had developed a system that uses a sound card to be able to measure frequency vs. voltage. So I could make my own hybrid woofer arrangements and accurately measure all of the T/S parameters. I can also measure box freq. I realize that's not a big deal now. There is a USB thing that does that. But writing that code and figuring out how to make it work was quite a good learning experience.

James.