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Hey guys...we need a little rallying here... - Page 227

post #6781 of 9844
"It usually takes special time alignment to achive this, and usually the two drivers are in what is called phase quadrature from each other, meaning they are 90 degrees apart in opposite directions so that the summation is 0 degrees, or 0 degrees of error, as you are still controlled by the frequency response and its phase. Crossovers in phase quadrature do not have a reverse null - if you flip the polarity the response will not change (or change very little)."


that sounds a lot like the driver placement criteria Tom Danley used in this Unity horn. The drivers are placed 90 degress apart at the crossover frequency and the crossover phase shift brings them into alignment
post #6782 of 9844
Quote:
Originally Posted by omegaslast View Post

Isnt some guy selling zilch pcb boards? simply by selling zilch pcb boards he technically trademarked the name (according to ash R, i dont know if thats true)) and thats probably what Ash R was referring to. If you have a trademark then you cant let people infringe otherwise you lose it (i know this to be true).

is the guy selling zilch pcb boards the one emailing you?

Yes, but they weren't actually sold as "Zilch boards".

Either way, it's all pretty strange, but it's over and done with.....I'm movin' on. biggrin.gif
post #6783 of 9844
Quote:
Originally Posted by Erich H View Post

Yes, but they weren't actually sold as "Zilch boards".

Either way, it's all pretty strange, but it's over and done w..I'm movin' on[/B on. biggrin.gif


Good for you sir! Keep charging ahead. There's no time to waste.


So, how do we get some of those custom baffles? Email, PM?
post #6784 of 9844
Quote:
Originally Posted by jzagaja View Post

This is SEOS-15 on a front panel, use any 15" woofer - here it is BC 15CL76 and tweeter is BMS 4550.

Can you describe how the front panel is mounted to the box? In your picture it appears there are a number of screws in the box surrounding the front panel (at least that is what I am assuming they are). I am certain they serve a purpose so I am curious as to why they are there as they don't seem to be affixed to the front panel in any way?

Also I am assuming this is the resin version, is that correct?

If it comes in matte white, could it be painted using auto paint or other very durable coatings without affecting the material or the sound?
post #6785 of 9844
Quote:
Originally Posted by Erich H View Post


And you know, when all of the pallets of flat packs are moved into one area, it really does make me look a bit nuts. biggrin.gif

Perhaps we should have you committed. tongue.gifbiggrin.gif

Pictures... If time permits.
post #6786 of 9844
For those of you who would like to learn a little more about trademarks, Ash is referring to Common Law application of trademarks. If you google it there should be lots of info on the matter. Please note that this does not apply to the design, but rather the use of the mark (i.e. Zilch). As to how it applies in this case, it is not as simple as many would like. There is a lot of noise that needs to be filtered before a reasonable assessment can be made.
post #6787 of 9844
Quote:
Originally Posted by Raul GS View Post

For those of you who would like to learn a little more about trademarks, Ash is referring to Common Law application of trademarks. If you google it there should be lots of info on the matter. Please note that this does not apply to the design, but rather the use of the mark (i.e. Zilch). As to how it applies in this case, it is not as simple as many would like. There is a lot of noise that needs to be filtered before a reasonable assessment can be made.
Sure there's tons of info, but it's been voiced over and over that we want to move on.
post #6788 of 9844
Quote:
Originally Posted by JackNC View Post

"It usually takes special time alignment to achive this, and usually the two drivers are in what is called phase quadrature from each other, meaning they are 90 degrees apart in opposite directions so that the summation is 0 degrees, or 0 degrees of error, as you are still controlled by the frequency response and its phase. Crossovers in phase quadrature do not have a reverse null - if you flip the polarity the response will not change (or change very little)."


that sounds a lot like the driver placement criteria Tom Danley used in this Unity horn. The drivers are placed 90 degress apart at the crossover frequency and the crossover phase shift brings them into alignment

I'm not sure I picture what you mean by "placed 90 degrees apart" at the crossover, but that doesn't sound like what I am referring to.

Let me use the example of a textbook 1st order filter. It assumes that the driver acoustic centers are time aligned, meaning that their impulses occur simultaneously and the time of flight for both drivers to the listener (or mic) is exactly the same.

Speakers and crossover circuits are both minimum phase devices. This means that the phase response can be derived directly from the frequency response (using what is called a Hilbert -Bode Transform). Now if two drivers have infinite flat bandwidth then their phase will be a straight line at 0 degrees. If the driver begins to roll-off naturally then there will be a phase response that corresponds to this change in frequency response - and that phase is mathematically predictable. A crossover is the same way, the phase is predictable based on its roll-off. But It is how these drivers with their crossovers sum together that becomes non-minimum phase.

Using our perfectly flat drivers with infinite bandwidth, the "Denovo-777 series", and we cross them over with first order slopes, we find that the woofer rolling off with a first order lowpass now has a phase shift at the crossover of -45 degrees in acoustic phase. The tweeter on the other hand is rolling off with a first order high pass and has a phase shift at this point of +45 degrees. When they sum the final acoustic response is flat and the summed acoustic phase is back to 0 degrees. So it is still minimum phase, just like the drivers were. There was no special placement the 90 degree phase difference was all due to their roll-offs. .

Now, this minimum phase summation doesn't hold up as we move up in crossover order. For the textbook fourth order in-phase L-R crossover type, for example, even though the summed frequency response may sum flat, the summed phase response has an extra 360 degrees of phase rotation compared to minimum phase. This translates into group delay in the summed response. Whether this is audible or not has been hotly debated.

The thing about the Alchemy though is that despite its higher order slopes it doesn't possess this extra phase rotation. Its phase still correctly follows the frequency response. This make is fairly unique.

Jeff
Edited by Jeff Bagby - 1/25/13 at 2:52pm
post #6789 of 9844
Those alchemy's sound awesome. I haven't really studied signal theory but I am a math geek, so I am found of the concept.
post #6790 of 9844
Thread Starter 
thanks jeff.

could the 360 degrees of phase rotation be brought back to zero by moving the tweeter in a 4th order system one full wavelength in distance back from the woofer?

it would seem that the frequency response would be unaffected in the crossover, but the phase would be brought back one full cycle (360 degrees) by doing this.

or, is that not how it works either? :-)
post #6791 of 9844
Thank you Jeff for the detail explanation.
post #6792 of 9844
What do we have here?

Might lighten up Erich's packaging duties a little..although having them handle the flat packs would have been easier on him. wink.gif
post #6793 of 9844
Quote:
Originally Posted by avpassion View Post

Can you describe how the front panel is mounted to the box?

Screwed and glued. This is shiny fiberglass.
post #6794 of 9844
Quote:
Originally Posted by LTD02 View Post

thanks jeff.

could the 360 degrees of phase rotation be brought back to zero by moving the tweeter in a 4th order system one full wavelength in distance back from the woofer?

it would seem that the frequency response would be unaffected in the crossover, but the phase would be brought back one full cycle (360 degrees) by doing this.

or, is that not how it works either? :-)

Ah, you're a quick study. I like that. That's the idea. But it gets a little more complex than that with real drivers. Something else that sometimes works well and only has phase error at the top end is to have the tweeter positioned a half-cycle behind the woofer and connect it with inverted polarity. Remember, with some crossover points a full cycle can be a pretty large distance. But when we are working with these pro-sound drivers we are usually dealing with horn loading that moves the tweeter back quite a ways already. In addtion to that, many pro-sound woofers that are designed to use the dustcap to help extend the upper end will end up an acoustic center along the former resting between the cone and the dustcap. This is what I get with the Beta 8-A, its acoustic center is quite a bit forward that of most hi-fi drivers. Also, even though these drivers sum with correct phase through the crososver they are not time correct; due to the tweeters offset there will be error there. Again. audibility is debated, but why not grab every little bit that we can, right?
post #6795 of 9844
Quote:
Originally Posted by AudioJosh View Post

Those alchemy's sound awesome. I haven't really studied signal theory but I am a math geek, so I am found of the concept.

I like math geeks. I hear you played a role in the SEOS design - it's very impressive.

Jeff
post #6796 of 9844
I think I'm going to ask for a Tempest sealed baffle to fit the 1' cu flat pack. I think it would be a good solution for decent extension in a smaller package.
post #6797 of 9844
Quote:
Originally Posted by jzagaja View Post

Screwed and glued. This is shiny fiberglass.

jzagaja, thank you for the reply. May I ask what it is is screwed and glued to? It may be obvious so please bear with me for a moment while I attempt to explain. Based on your picture, the circumference of your box is larger than the front baffle. Given the apparent thickness of the edge I would guess that it is probably the same thickness as your box walls. At the same time the baffle does not appear to be inset into the box. Further, given what appear to be screw holes around the edge of your box I am assuming that you mounted a front panel on your box with holes cut out to accommodate the woofer and wave guide and then screwed & glued the fiberglass baffle to it from behind. Am I correct?
post #6798 of 9844
Thread Starter 
thanks again jeff.
post #6799 of 9844
I wonder if we use a similar xo topology Jeff. My eminence 8" build is also min phase like that. It's with the alpha 8a and has about a 1500hz cross over iirc. I gotta update my thread on diysoundgroup. I imagine mine is a bit cheaper, but doesn't use as nice of waveguide or CD.

EDIT TO ADD - Here's a measurement showing the phase. Most all other speakers wrap around the 1000 to 2000hz range (depending on xo etc.). I don't think this has any audible advantage personally. Even though I do like this speaker a lot.


Edited by tuxedocivic - 1/26/13 at 6:35pm
post #6800 of 9844
How do you place an order from DIY sound group for Canada?
It always says there are no quotes available ><.
post #6801 of 9844
Quote:
Originally Posted by tuxedocivic View Post

I don't think this has any audible advantage personally. Even though I do like this speaker a lot.
I also prefer speakers with similar phase response. It's easy to do with drivers that have a wide bandwidth and smooth roll off.
post #6802 of 9844
Quote:
Originally Posted by Jeff Bagby View Post

Ah, you're a quick study. quote]
, whcih,
Not me, I'm a little slowe or at least I engaged mouth too soon. So it seems that the synergy is the opposite of your crossover in that regard. They start out with the midrang just under 1/4 wavelength (at the crossover fequency) down the horn form the CD, which means the CD's output lags by 90 gegress at that frequency. They use crossover delay to bring the mid and the CD into phase alignment. There is considerable low pass filtering going of the mid's output so I suspect this means it needs less electical filtering and because of that there is more delay in the electrical high pass filter for the CD and that is what allows/causes the phases to align. Does that sound reasonable? Tom Danley gives a pretty lucid description of this in the patent but he is vague on the crossover details.
post #6803 of 9844
Quote:
Originally Posted by jzagaja View Post

FP15 prototype on my turntable smile.gif


That would be really great with a squared-off baffle and a separate piece that incorporates a roundover in the space between baffle and cabinet with a grill. Then there wouldn't be that step between baffle and cabinet.
post #6804 of 9844
Quote:
Originally Posted by avpassion View Post

jzagaja, thank you for the reply. May I ask what it is is screwed and glued to?

Give me a day or more so - will unscrew after I make crossover smile.gif
post #6805 of 9844
Quote:
Originally Posted by Thatsnasty View Post

How do you place an order from DIY sound group for Canada?
It always says there are no quotes available ><.

Your lucky, you live near the border, so you could have it sent to one of those US mailbox places like http://cbiusa.com/. I live in Toronto, so its more of a PITA to drive down there and back.
post #6806 of 9844
Quote:
Originally Posted by Erich H View Post

The problem about some of these 'custom' baffles and boxes is that I don't think it's a good idea to post all of them on the site because at some point, the number of options just makes things too complex.

Not sure that adding baffles for another woofer significantly adds to that.

And isn't that preferable to people not knowing the product is available, or if they do, having to bug you to order it as opposed to just click/buy?
post #6807 of 9844
Could have a custom baffle option and list the different custom baffles and have one for something different. Just a thought. The prices could change with options, wich can be easily done with you magentto.
post #6808 of 9844
Quote:
Originally Posted by noah katz View Post

Not sure that adding baffles for another woofer significantly adds to that.

And isn't that preferable to people not knowing the product is available, or if they do, having to bug you to order it as opposed to just click/buy?

It's not adding baffles that's really a problem. It's trying to explain why they can order the Tempest or other models in either ported, sealed, or slot ported designs. What makes each one different, etc. Then having them select the correct baffle, and the correct boxes to match them up, or if there is a box to match that baffle style. Those 3 options would make me have to get 3 different baffles, and 3 different boxes for just one design. eek.gif And keep in mind the CNC company won't cut 10 boxes here and there. It's got to be at least 80 to keep prices lower. So some stream lining has to happen or I won't be able to keep up.

Just for these standard boxes:

Overnight Sensations
Overnight Sensation MTM's
Hitmakers
Nano Neos
Amigas
New Aurasound model
SEOS 1 cuft
SEOS 2cuft
SEOS 2 cuft ported
All 8" woofer waveguide speakers
Some flat packs with no woofer cutouts.....


I've got over 20 pallets of flat packs right now. Because of how large the sub flat packs are, there will be at least 18 more over the next 2 weeks. That doesn't count random pallets of subwoofer samples and baffles. So 40 pallets.

Then of course realize that there's currently only one person tracking and packaging all of that. Then picture pallets of waveguides, compression drivers, keeping up with all crossover components, woofers, and all that stuff. And there are other things coming as well (not waveguide related). So while adding a few more options doesn't sound like too much, it can be. biggrin.gif As much as I'd love to help with every design that gets made up, it's nearly impossible.

The only other option I have to speed things up at this point is hiring someone part time. There were a lot of put downs, insinuations, and other junk that went on over the past month or so to possibly make me stop helping with this or undermine this particular project. All that did was push me more towards taking all of this up another notch. smile.gif I've been doing a lot of thinking on that and I do have some ideas. Just not sure yet.
post #6809 of 9844
Wow... That's a lot of stuff. I can't imagine.
post #6810 of 9844
Quote:
Originally Posted by AudioJosh View Post

Your lucky, you live near the border, so you could have it sent to one of those US mailbox places like http://cbiusa.com/. I live in Toronto, so its more of a PITA to drive down there and back.

I had my friends mom do this for me.... to 3x Denovo 360's and 3x JBL 2226H's from Ebay.
This is how I built the 4pis around 1500~ for all three. But It's still really inconvenient for me to have to do.
I'd rather just get it sent here and pay the extra money, honestly the boarder screws us so hard even though I'm closer to US then 99% of the rest of the US..

I'm just waiting for Erich to organize the flat packs, I wanted to pick up a 1.25cuft sub box for the TC-3000 12" I found on kijiji.
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