[AJinFLA]

Would love to get in on the discussion, but we just got walloped by Irene and have been without power for the last day. Even the cellular data network is pretty much totally down. Hopefully back online tomorrow...

Hang in there Neeko. Forget speakers and take care of the important stuff. Best wishes to all those affected by this storm. Really made a mess going up the coast.

regards,

AJ

[Duke]

Very well thought-out topology, congrats on obviousy getting the details right, judging by the listener comments.

Just visited your website; I expected the price to be three times what you're charging.   You are offering a superb value, AJ.  I hope the marketplace rewards you for it.

Duke

[neekomax]

Thanks AJ. Focusing on getting meals together with only a grill. Have a generator, but it won't start   

Makes me appreciate the ease with which we live and comforts we normally have.

And the speakers will get here when they get here

[JDUBS]

Hi Jim,

I've updated the site a bit, but if you have any questions, you can e-mail me at soundfield (preferred), or pm me here. Thnx

Very cool.  I love the concept! 

-Jim

[James Romeyn]

Again: Definitely a design that makes one wonder why we haven't been buying and listening to it for years already.  I suppose one reason is the more recent widespread availability of lower cost plate amps with built-in Xo to the DIY community.  I could see this becoming a great industry trend if not maybe even a standard.  Let us now officially christen this (powered bass/passive mid/treble) the "AJ" topology...or insert better label here.  Your philosophy has much better potential for success and acceptance in high-end than fully powered monitors.  In pro audio fully powered makes some sense because higher SPL is more desirable.  In high-end, we likes our favorite amps for mid/treble much more than low cost digital amps for this range.  Smart!

So AJ (sorry if covered elsewhere): is there a passive high-pass mid crossover?  What is low-pass bass pole?  Is low-pass bass pole tunable? 

Also, kudos for highlighting the bass-mode flattening power of employing a sum total four bass sources in the room (your two speakers + two subs).  As you mention, the mains in this case, the SFAM1, should absolutely run the powered bass driver full range and NOT be high-passed, resulting in more smoothing effect of the bass modes.  This is anti-intuitive for audiophiles not familiar with this technology, which Duke has long espoused and promoted.

Two bass sources attached to the mains results in less smoothing than  locations other than the mains (IOW four discrete subs), but there is still great potential benefit.  I'll send a PM that may help in dual sub placement with your apparently fantastic new speakers.     

[bummrush]

I think you came out ahead with just the white front.  It goes perfect with the light colored wood

[jackman]

James, I don't follow you.  Are you saying not to high pass the mids (or coax in this case) or not to high pass the bass drivers? 

I don't have SAM1's but in my speakers I high pass my monitors at 150hz and use subs to cover frequencies from 150hz on down.  The system sounds much better than it did when I was running the monitors full range. 

[AJinFLA]

Very well thought-out topology, congrats on obviousy getting the details right, judging by the listener comments.
Just visited your website; I expected the price to be three times what you're charging.   You are offering a superb value, AJ.  I hope the marketplace rewards you for it.

Duke

Thanks Duke. I'm staying clear of the studio guys for right now, don't think they would want a passive/active like this, though the closest thing to these might be the $9k ( ) Genelecs.
I see you are locked in mortal combat with some heavy hitters in the studio .

cheers,

AJ

[AJinFLA]

Again: Definitely a design that makes one wonder why we haven't been buying and listening to it for years already.  I suppose one reason is the more recent widespread availability of lower cost plate amps with built-in Xo to the DIY community.  I could see this becoming a great industry trend if not maybe even a standard.  Let us now officially christen this (powered bass/passive mid/treble) the "AJ" topology...or insert better label here.

Hi James,

That would be a huge stretch, given the Infinity Overture 1's and even Neeko's DefTechs, which feature powered subs. The niche I wanted to fill, is what I've seen in about a 1000 threads, something along the lines small/bookshelf that doesn't need a sub...followed by 1000 responses of "try this 5.25 - 6.5 inch 2 way"...huh??? How on earth is a 6.5" driver going to displace the necessary air for subwoofer frequencies? (physically impossible). Why would you want you midrange driver producing those sort of excursions? (you don't ).
So that's it. A speaker that answers that question. Nothing special. Basic physics.

Your philosophy has much better potential for success and acceptance in high-end than fully powered monitors.  In pro audio fully powered makes some sense because higher SPL is more desirable.  In high-end, we likes our favorite amps for mid/treble much more than low cost digital amps for this range.  Smart!

The former...we'll see, the latter absolutely.

So AJ (sorry if covered elsewhere): is there a passive high-pass mid crossover?  What is low-pass bass pole?  Is low-pass bass pole tunable? 

Yes (200hz). 200hz. Yes, though inadvisable. The plate amp is an "off the shelf" unit that has all the controls, none of which should be required other than setting the level to match the main amp.

Also, kudos for highlighting the bass-mode flattening power of employing a sum total four bass sources in the room (your two speakers + two subs).  As you mention, the mains in this case, the SFAM1, should absolutely run the powered bass driver full range and NOT be high-passed, resulting in more smoothing effect of the bass modes.  This is anti-intuitive for audiophiles not familiar with this technology, which Duke has long espoused and promoted.

Two bass sources attached to the mains results in less smoothing than  locations other than the mains (IOW four discrete subs), but there is still great potential benefit.  I'll send a PM that may help in dual sub placement with your apparently fantastic new speakers.     

Thanks. I'll keep an eye out for it. And yes, I have already advised on additional subs placed around the room for spatial smoothing over a wider area, though I also explained that for single seat listener, eq will work fine too (though it cannot fill holes)...if needed.
I've got some other tricks up the sleeve to come, WRT modal issues...and practicality.

cheers,

AJ

[Big Red Machine]

I'm confused.  For a pair are there powered woofers in each speaker?  Where is the powered woofer in the cabinet and it's output?

[James Romeyn]

James, I don't follow you.  Are you saying not to high pass the mids (or coax in this case) or not to high pass the bass drivers? 

I don't have SAM1's but in my speakers I high pass my monitors at 150hz and use subs to cover frequencies from 150hz on down.  The system sounds much better than it did when I was running the monitors full range.

Jackman,
Two completely separate issues, sorry for confusing them.  I'd estimate the mid in AJ's system might be preferred with high-pass mid-range crossover.  Conversely though, I once heard a 10" sealed 3-way with absolutely no crossover on the 5" mid that sounded great, and have read of at least one other similar design.

Separately, on AJ's active bass driver: audiophiles would be wrong to add a high-pass filter on the active bass driver if/when adding subs.  There is huge smoothing of the room's bass modes running AJ's active bass driver full range, as is, when adding any number of subs. 

With four bass drivers in the room (2x AJ, 2x subs), theoretically, and I'm 99.999% positive in this case, one of the bass drivers should absolutely be inverted.  And the best one to invert is the one resulting in the least overall perceived bass, which results from and indicates the greatest smoothing of bass modes in the room.  Wordsmith Duke calls this "Deconstructive Interference".  Whatever slight bit of power might be lost (about zero with four bass drivers) in the lowermost or lowest half octave is hugely overshadowed by the smoothing effect from 40-150Hz, exactly the range AJ mentioned earlier above. 

If only one sub is added (3 total bass drivers), per Duke, Earl Geddes' and Todd Welti, one of the three subs should be above ear level, in this case that would obviously be the solo sub, unless AJ's bass driver is normally above ear level (doubtful).  This height requirement does not apply to four subs but rather only three. 

In the case of 3 subs, the decision to invert one bass driver must be balanced by the positive smoothing effect of the bass modes vs. potential lowermost or lowest half octave power loss.  In this case inverting one sub inverts 1/3rd the bass output while with four bass drivers only 1/4 the output is inverted.         

I sent a PM to AJ with my original Golden Ratio siting instructions for four solo subs.  It may be old news to him.  AJ may modify the instructions to apply to users employing his two main speakers and adding either one or two subs.  It's really cool that users can toss together even a passive sub and power it with his plate amp!  It's important to note that matched high-Q subs will provide much less bass smoothing effect than low-Q or non-matched high-Q subs.   

At a show Duke and I did last December, following my siting instructions, after setup Duke made adjustments for only about 90 seconds with no acoustic treatment and we never 2nd guessed the sound after that.  It was some of the best sound I've ever heard.  I heard absolutely no resonant bass modes all day.     

[srb]

It's really cool that users can toss together even a passive sub and power it with his plate amp!

I thought from AJ's earlier post in this topic that the passive slave output was not an option at this time:
 

One quick note, due to warranty issues, the slave output off the amplifiers is not an option right now, until further notice.

Steve

[James Romeyn]

Hi James,

That would be a huge stretch, given the Infinity Overture 1's and even Neeko's DefTechs, which feature powered subs.

Oh, drats, forgot about the Infinity and I just read about it within the last month or so...the joy of approaching senior discounts (that's senior, not senor...oh well, with Mexico reclaiming the west, maybe both).   

I'm sure any speaker with powered bass and passive high-range was less-well implemented than yours, and cost at least twice as much!   

The niche I wanted to fill, is what I've seen in about a 1000 threads,  something along the lines small/bookshelf that doesn't need a  sub...followed by 1000 responses of "try this 5.25 - 6.5 inch 2  way"...huh???   How on earth is a 6.5" driver going to displace the necessary air for  subwoofer frequencies? (physically impossible). Why would you want you  midrange driver producing those sort of excursions? (you don't ).

Duke and I get a kick out of speaker marketers and audiophooles subscribing to and promoting the idea of "small, super lightweight" bass drivers for "quicker response".  This is so dumb.  It's like replacing the low-E string on your guitar with a high E string and predicting better sound quality.  Earth to audiophile: mass is required for 58 foot long wavelengths!  Another analogy: I'm betting every penny I have on this lightning fast super bantam weight to beat Tyson in his prime (before he started eating lunch in the ring).  Now the problem is the bantam is 5' tall, so Tyson just holds one hand out to space the bantam from Tyson's other hand while the bantam swings at the air with lightning speed, then Tyson connects with his loose hand one time and the bantam lands four zip codes away.  It's like designing a diesel motor with a power band like a 2-stroke.  Why?     

[Tyson]

James you are so right - I am convinced that many people just don't like the sound of real bass    Low bass if full, powerful, and it undulates.  Upper and mid bass should be punchy, but low bass should by labyrinthine.

Also, I'm not a boxer, but I am in my prime

[jtwrace]

I am convinced that many people just don't like the sound of real bass  

No truer words have been spoken...   

[James Romeyn]

Mike, I mean Tyson...

What concentric speaker ya'll sleepin' wit in da ghheto lately?   

[AJinFLA]

I thought from AJ's earlier post in this topic that the passive slave output was not an option at this time:
 
Steve

Yes, that is correct. The slave output will have to be different, to prevent someone from accidentally plugging bananas or bare wire from their main amp into the output terminals. That would not be good!
It was the easiest method to use the existing banana terminals on the plate amp, but not the safest. I will come up with a proprietary scheme for connecting to the slave output. It's still in the mix.

cheers,

AJ

[jackman]

Hi James,
I agree with you on the bass driver and the high pass.  I thought you were refering to the mid driver not needing a high pass.  I have a system that uses monitors crossed over to subwoofers built into the stands.  I originally ran my monitors full range with the subs but it sounds much better with a 150hz high pass filter on the monitors (recommended by the speaker designer).  After owning speakers with active (adjustable) subwoofers, I could never go back to traditional passive full range speakers.  How do people who own full range, passive speakers, dial in the bass?   

Your comments about small 2-way monitors with "great bass" made me chuckle in agreement with you.  I love reading about compact 2-way monitors with 6.5" or smaller woofers that produce "deep bass" in the "I estimate it is at least 25hz" range, and play high spl's, with at least 95dB sensitivity, oh, and with really good midrange response.  That's not asking too much of a 6.5" driver, right?   

Of course, I'm not talking about the Soundfield Audio Monitors in my comments above.  I've never heard these speakers but they appear to be well constructed/designed, and they have real woofers.  It's a very clever idea and I like the active sub/passive concentric driver combo and compact size of the cabinets.  Also, although I think you can get really great sound with traditional tweeter/midrange arrangement, the concentric driver is pretty cool looking, and probably very coherent, and doesn't take up as much baffle space as traditional separate drivers- which works is a good thing when baffle space is limited.  I hope to hear these someday and wish the OP the best of luck with his new company. 

Cheers,

Jack

[Tyson]

Mike, I mean Tyson...

What concentric speaker ya'll sleepin' wit in da ghheto lately?   

Running the GR Research V2's, fully active, built them myself -

[Cacophonix]

From the pics, i could not see where the speaker terminals are located 
I'm assuming that the BASH powers only the woofer, and has no connection to the coaxial driver.