Calling John Krutke -- I think you will find this interesing

[Hank]

Cosmetically, it looks very nice, Dylan. Good luck with the final production units' sound - I hope you find a good volume buyer/distributor if these really represent a price/performance benchmark.

[Dave Bullet]

Hi Dylan,

Your drivers certainly have great visual appeal and differentiate you from much of the competition. I believe there is a niche in the market to fill, and it seems you are well on the way. I think it adds to your credibility with having independent tests performed by the likes of Zaph.

I'll follow your progress with interest and with you all the best.

David.

[ch83575]

Cone design is WAY out of my league, but just out of curiosity, what type of resin are you using in the fiber cones? From my experience with woven fiberglass it seems that the fiber itself would play a back seat to resin used in terms of cone rigidity and internal dampening. All of my experience is with woven fiberglass with epoxy resin used for boat-building, and it would seem to me that it would be a less than ideal material for cones, so I assume a different, more pliable, resin must be used here?

Dylan, I really admire your dedication. This is a fascinating endeavor you have undertook, and I am glad that you decided to share it with us. One thing I keep wondering is how much of this you specify and how much is stock? For instance, did you come up with that cone geometry, or do you have to stick with the tooling that whoever produces them already has?

Keep up the good work, and keep us informed.

[Dylan Matlow]

Cone design is WAY out of my league, but just out of curiosity, what type of resin are you using in the fiber cones? From my experience with woven fiberglass it seems that the fiber itself would play a back seat to resin used in terms of cone rigidity and internal dampening. All of my experience is with woven fiberglass with epoxy resin used for boat-building, and it would seem to me that it would be a less than ideal material for cones, so I assume a different, more pliable, resin must be used here?

Dylan, I really admire your dedication. This is a fascinating endeavor you have undertook, and I am glad that you decided to share it with us. One thing I keep wondering is how much of this you specify and how much is stock? For instance, did you come up with that cone geometry, or do you have to stick with the tooling that whoever produces them already has?

Keep up the good work, and keep us informed.

Thanks, its tough trying to keep focused between this and 21 credit hours of class 8x)

I had asked if they could handle pressing a polyimide film into the fiberglass weave for the black cone version, I'm still unclear on if they did that or used their own status quo technique (likely polyester or possibly an epoxy system?). Polyimide film would have a non-composite specific rigidity 25% less than the best and most rigid grade of polyester resin, however the damping coefficient should be 5-10x higher. Accordingly with the 4khz 6dB breakup mode I believe they likely used a rigid polyester or epoxy system instead of the polyimide (which shouldn't have had much of a breakup mode at all if my logic is right). It can be a bit of a difficulty to communicate with suppliers sometimes to say the least...

The cone profile however is stock ops: I know the generalizations, however I don't have the FEA tool required to truly optimize the cone geometry. I will have to buy one before too long, hopefully someone will cut me a good deal given the current nature of my work...

The weave size of this next cone is substantially smaller and the profile is slightly different, all I can do is hope it is up to par that way I don't need even more modifications. I would try to specify a nice paper pulp mix but I've lost my trust in terms of batch consistency for any kind of natural fiber or pulp where the raw material quality can change between seasons...

As much as I would like to try end grain balsa as a core material (the material properties are pretty sick) I pretty much have to rule it out at least for a little while.

I've also been contemplating the use of sub-micron ceramics and things like SiC whiskers as fillers in plastics since they have very low bulk densities... I imagine that trying to fully saturate a plastic with them and then injection mold would prove difficult (think sol-gels or cornstarch+water even), however if you start with the nanopowder in a mold and inject the plastic/metal/whatever slowly to let it infiltrate the porous space with a bit of agitation I'm sure the resulting 3d matrix composite would have quite impressive properties...

Anyone know if theres prior art regarding this?

The closest thing I can find is functionalised nanotubes for use in epoxy systems... Although I would be interested in throwing nanotubes into ferrofluids to increase the thermal conductivity among other things...

I sure hope someone will be interested in these 6.5s on a larger scale... Or at the least I can find a nice job within the industry that I would actually enjoy. I sure would be productive since this sort of thing is my passion. I love tinkering with speakers...

PS. I do all of the motor design, thats 100% USA engineering by me.

[Dylan Matlow]

That cone sure trimmed off a bit of mms didn't it?
The glue joint at the former could be nicer and the phase plug needs to be a larger OD so it mates more closely with the former and the use of a gold binding post would be a good touch as well as symmetrical lead wires.

Now it is just a matter of getting it measured, I would rather like to see how a few other cone materials measure up before making the final call but at least this unit will make it clear if the motor and suspension are working properly...

Qms is a bit low... Accordingly I would hope it has quite a bit of control over rocking! So it is not completely a bad thing, but it might have had a nicer looking set of t/s if it was over 3 (kinda caught me off guard)...

[Dylan Matlow]

Black? Finish Like this? Hard to say...

Regardless this unit is headed to the klippel next to make sure there's nothing terrible looming over this unit. I'm trying my best to get a very nice composite cone put together for this as well as a thermoplastic version.

[cjd]

I like the raw aluminum, but then the glue ring really sticks out. Dunno. Looks nice. Have you listened to it at all?

C

[Hdale85]

What kind if a price range are these drivers going to be in?

[Dylan Matlow]

What kind if a price range are these drivers going to be in?

It will be here monday or tue so I'll get a chance to listen to it by the end of the week assuming it didn't get dropped off the back of a plane.

The price point is still flexible at this point since all the costs are not final. I would like to see it at parts express or similar distribution channel for $75/ea or a bit less depending on the exact markup they have, final cost per unit, and what cone I stick with. Needless to say it would cost a bit less direct, however the volumes are lower and all of the proceeds from this as well as the 5.5" project help to fund future projects/experiments.

If I set up a group buy and there is a good response it will be in the $50/ea range.

[Dylan Matlow]

Well it should be on its way now at long last it will be heading for a battery of testing on the good ol' klippel. Hopefully it will arrive here by wed.

I'm still in limbo as to the cone material that will finally be used in production but it will be nice to see how the BL vs. X and Cms vs. X look at this stage before throwing more money at the cone









This is the predicted BL vs. X The top one is the 8 ohm version and the bottom is a 2 ohm split coil version that I like the most (other than its edge wound equivalent) even though its one of the least sensitive of my designs, it has a frighteningly flat BL vs. X simulation... Also the liberal copper in the gap excites me a little bit.



Family of 2 ohm curves:



Split coil it a bit tricky in terms of QC though since the top plate thickness as well as the wire winding length and spacing between the winds are highly critical specifications that can't drift much from the nominal value otherwise the BL vs X. graph does all kinds of less than desirable things. It should be quite an uphill battle to stress such tight tolerances .

[SQdude]

FR vs Imped. suggests no copper in the motor, am I correct? Why not? It would be interesting to see the distortion plot of this driver vs same one with copper.

[Nemophyle]

I don't want to be pessimistic, but IMO you can't do a competitive 75$ driver without copper or alu shorting in the motor, or any other motor design feature to cut down the inductance and related harmonic distortion, with dayton RS series around being 2 times cheaper and having such features (especially if you then send a pair to zaph for being tested :P )

If you do the motors by yourself and it's the thing you have the more control on, you should seriously think about doing a SOA motor and selling the driver 10-20$ more, i think you would have clearly more of a market this way.
Cause if you look at it seriously, 75$ 6" drivers with basic motors are pretty common, and are getting less and less feedback cause drivers with better motors for the same price happenned to pop around (Dayton but also peerless and new seas prestige drivers)

Why not ask the motor experts around (caplocks and feyz comes to mind) about the best way to use copper in a clever way (quantity and price of copper vs relative improvements in performance)

also we could be mistaken and your motor being an advanced one, even if for what i see in the curves it doesn't look to be the case

just my 2 cents, it doesnt matter much to me anyway since i'm in europe and will probably never get one of your very nice looking drivers

[EDIT: Sorry, it looks reading at your last post that your driver have or may have copper in the gap, also split coil design can/may improve distortion performance, so i may be totally off with my comment. Though, i'd really like if you could be more specific about those points ]

[Dylan Matlow]

I don't want to be pessimistic, but IMO you can't do a competitive 75$ driver without copper or alu shorting in the motor, or any other motor design feature to cut down the inductance and related harmonic distortion, with dayton RS series around being 2 times cheaper and having such features (especially if you then send a pair to zaph for being tested :P )

If you do the motors by yourself and it's the thing you have the more control on, you should seriously think about doing a SOA motor and selling the driver 10-20$ more, i think you would have clearly more of a market this way.
Cause if you look at it seriously, 75$ 6" drivers with basic motors are pretty common, and are getting less and less feedback cause drivers with better motors for the same price happenned to pop around (Dayton but also peerless and new seas prestige drivers)

Why not ask the motor experts around (caplocks and feyz comes to mind) about the best way to use copper in a clever way (quantity and price of copper vs relative improvements in performance)

also we could be mistaken and your motor being an advanced one, even if for what i see in the curves it doesn't look to be the case

just my 2 cents, it doesnt matter much to me anyway since i'm in europe and will probably never get one of your very nice looking drivers

[EDIT: Sorry, it looks reading at your last post that your driver have or may have copper in the gap, also split coil design can/may improve distortion performance, so i may be totally off with my comment. Though, i'd really like if you could be more specific about those points ]

I'd be glad to explain -- Although I'd love input from resident experts as well...
The 8 ohm variant does not have copper directly in the gap, instead there is a short path (6mm thick aluminum) under the top plate inside of the magnet ID designed to help make the Le vs X. curve symmetrical which is my biggest concern with a high excursion overhung driver. I'm also trying to get the absolute highest sensitivity I can manage with a pole of this size, which isn't the case with the 2 ohm split coil unit.

Also if you take a look at the BL vs X. simulation for the 8 ohm, although it isn't quite as flat as the split coil variant I did take quite alot of care to make sure that it is as symmetrical as possible, just hopefully the coil is properly centered in the gap in manufacturer which is always a bit of a concern...

With split coil you have other issues to keep in mind when designing placement of the sort paths, although this split coil unit is using a T pole variant with a pole extension on top of the T, with normal overhung designs it would be quite common simply to put a short path under and above the T in order to help out Le vs. X.

In a split coil design Le at the resting position will be very low if theres a short above/below and Le will go up in both the + and - travel directions which can lead to some problems finding the center of the gap at high drive levels since the BL is so very flat in this particular split coil design. Therefore at great expense in terms of gap real estate I'm placing the copper short paths directly inside of the gap in order to make a good attempt to alleviate the issue. BL shouldn't be an issue for car audio if the mms stays in check. The 2 ohm version is stepping up to a 2" diameter VC and venting through the pole instead of a phase plug, so hopefully the price will remain in check even with all the extra copper...

I can try to get some of the production units made with copper on the extended pole for the 8 ohm version as a higher Q design if enough people are willing to put out an extra few dollars, but I know I'll be using the super small box higher sensitivity version myself.

Also if you compare to the dayton aluminum with a whopping coil length of 12.5mm (I think) the impedance at 2k and 20k are much higher than mine even though my coil length is 31mm

The dayton RS 7" is only a tad lower on the Le front than mine. As for the shape of the impedance curve, I'm not too sure on the details but aluminum starts having a bit of a skin effect higher in freq, I'm not 100% sure on where it starts being an issue but for now i have to head to class so I can't look it up Just something to think about though.

[Dylan Matlow]

If you were wondering, a 1mm thick short on the pole of the 8 ohm version will result in a drop of the BL to about 86% of its current value.
a 1mm T pole with inner pole extension on the top yields 92.5%... This is a bit flatter in terms of BL vs. X as well and a minor enough change in the OD of the pole that saturation concerns aren't too huge in terms of hurting symmetry... The B in the pole is about 2T though... As the steel becomes more and more saturated, air begins looking like a better path for that magnetic energy to take

I'm rather liking this T pole version since it is still in the 89dB/w range and still rather likes a small box... I wonder what these 2 extra short paths (copper this time) as well as the extra machine time on the pole will do to the price per unit...

I'll have a better idea of what can be done to the Le vs. X after I get klippel results for the current unit, its entirely possible that I will need a T pole and a smaller OD on the inner pole for the pole extension if the Le for the negative voice coil travel is much lower than with a bit of positive travel...

I wish i had a more reliable method of simulating AC effects...

[Dylan Matlow]

I'm thinking about offering a 140mm diameter dual magnet version in addition to this 120mm magnet structure (which nets about 6% more BL more or less depending on the pole configuration), some of which will have a minor T pole with extra shorts if the price/benefit is right, some of which will be on the normal pole version as well yielding over 90dB/w... It would also give a good chance to see how the distortion differs in the real world between the short combinations.

I'm also weighing the options of having some of the units with a regular mineral filled poly/high quality paper cone, as well as offering a few deep anodized aluminum cones or possibly a sandwich cone with a low density core... It would increase the per unit costs across the board to have this flexibility and limit the availability of any one given unit series if it goes substantially better than the others... Also I would have to move out over 50% of the stock, or have a decent number of order commitments for a given variant before deciding what was the biggest hit, what needs improved (etc.) and ordering again.
(looking for feedback)

[cjd]

You have T/S data on this last variant? (did I just read right by it?)

[Dylan Matlow]

You have T/S data on this last variant? (did I just read right by it?)

The only thing that would change between the motor variants is the BL
8.463 No short, 120 mag
7.83 T Pole 1mm short, 120 mag (projected)
8.97 No short, 140 mag (projected)
8.30 T Pole 1mm short, 140 mag (projected)

I would expect the projected values and the measured values to be a little bit off, but this should give you a general idea.
The extended T pole has its 99% BL point at 3mm instead of 2.75mm with the normal pole. The chart follows:
BL%: eT/eP
99%: 3/2.7
97.5%: 5/5
90%: 10.2/9.7

There would be a much more pronounced effect if the short path was thicker than 1mm, however the B field in the pole reaches a maximum of 2.14 T in the pole with the larger magnet structure as-is so I'm not too inclined to trim off much more for the sake of sensitivity. Something tells me some people might actually want a bit lower of a BL value for a larger box with even more extension though, a little more in line with the extremis, however not quite that power hungry, say 87dB/w or so... I'm not too sure I'd ever use a 6.5" under 50hz though personally and you can just marginally squeeze out an f3 of under 50hz with this unit.

I think I would be most enclined to use it in a 3 way though, say 0.25 cuft per 6.5" tuned to 60hz, active 2nd order highpass @ 80hz to a nice 10-18" depending on what there is room for. This would keep the xmax under 6mm with 200 watts of drive per 6.5" and the BL over this range would be really quite flat. The implementation of a split coil design to my standards of QC I guess will be quite the challenge so I'm getting my feet wet with this unit and working my way on up

The last thing i want in a split coil, or a split gap/other technology is a peak centered at the 0mm position with faster than overhung rolloff in the BL like some other attempts at split coil or spaced coil systems...
Or a ripple in the BL due to variance in the winding lengths/spacing of the individual coils... The tolerances would have to be well within +-0.1mm for me to be 100% happy and I'm not sure if thats a feasible goal or not at the moment... It won't stop me from trying to refine the manufacturing processes a bit

I'll work on the next more complicated project after I tackle the one before it I figure its a good learning experience! If it pays for itself, great. If it lands me a job that I would really enjoy... Better. If one of my future ideas catches on and I can do this full time after school... I'll be a happy man

[Hank]

That is a large variety of cones, and doing all those with your initial order numbers will increase the cost of all versions for sure - maybe too much. In your business plan, have you approached distributors like PE and Madisound with your final specs and pricing? If you have found a distributor that's interested, ask what cone version they want and go with that for now.
Also, I know neodymium has increased, but have you considered it to open up the area behind the cone?

[Dylan Matlow]

That is a large variety of cones, and doing all those with your initial order numbers will increase the cost of all versions for sure - maybe too much. In your business plan, have you approached distributors like PE and Madisound with your final specs and pricing? If you have found a distributor that's interested, ask what cone version they want and go with that for now.
Also, I know neodymium has increased, but have you considered it to open up the area behind the cone?

I talked to PE awhile ago generally and they seemed mildly interested in what I was doing. I'll go ahead and drop them a line again though since I have more solid data and the project is rapidly drawing to a conclusion, as well as give Madisound a ring.

I was initially approaching this unit on the drawing board as a neo design, however the volitility of neo prices scares me just a little bit for future production runs, not to mention the gains to be had from the impact on the rear wave don't fully offset the price in my opinion, particularly since this unit isn't well suited for anything other than ported/horn and potentially TL but I haven't spent much time looking into that aspect.

I talked about offering different cones within the first order and it was looking to only ad about 10% to the cost due to batch startup costs and extra complications in managing the project so it really is something worth considering.

The more I think about it, the more I think that all of the units should have this very minor T pole arrangement with the short path, and just offer one unit with 120mm magnets and one with 140mm magnets. The impact on the low frequency distortion due to making the BL vs X a little more linear will be real, and it doesn't hurt to get that flowing current out of that steel pole's skin that is for sure. I'm also looking at the idea of putting some open cell foam onto the top of the top plate although in such a way as to avoid restricting airflow from the venting structure, it might not do a ton to help out with reflections coming back at the cone, but the cost/benefit is there given the price of the stuff, not to mention I think the units that have that foam look a little extra classy...

Thanks for chiming in, I'll ask Madisound what they think would be best for their customers as far as cone type is concerned, considering they carry the seas prestige line they would know best.

My real business plan is centered around the implementation of some new technology, this is really just a baby step for me however there is a good degree of potential to this project, I'm just trying to work out the issues involved with manufacturing before I have to tackle an even more involved project.

The 5.5" budget unit was a low involvement low cost project to prepare me against some of the issues that were sure to come up in this 6.5" project.

This 6.5" project gains the benefit of my prior experience as well as ads quite a bit to my value as human capital and hopefully will generate a little bit of interest.

Depending on the response to the 6.5" I'll go from there and expand to larger units or if the 6.5" goes particularly smoothly I'll present my formal business plan and hopefully get some venture capital or a spot inside Harman International (or the like). I like some of my ideas, but I could be bias .

[Nemophyle]

ooks cool ... kinda ... but i'd have preferred if they let go the "hype" effect, and did a drivers serie with good concave alu/mag cones and thoses outstanding usher motors, for a more decent price. I wonder if we will ever see that though.

It's a shame that the two companies doing the best motors, usher and scan are only doing soft floppy cones, and it's not a 550$ 5" beryllium driver that is gonna change the game for me ...

Excels are good but they're quite a big higher on nonlinear distortion, + they look plain ugly to me, + i don't like phase plugs.

i have good hopes for the new eton drivers ... if they ever show up, it has become quite a big vaporware since they were supposed to be out like 10 months ago.

Sp tech could have been cool but ... sloppy cones again it looks like.

So i will have to buy accutons 400 euros for a midrange driver, sigh ...

Maybe i should ask dylan matlow

i post that here since joecarrow was kinda following me, could give you some ideas

[Hank]

Good that you're going with the T-pole thing.

...this is really just a baby step for me however there is a good degree of potential to this project...

Oh yes, you told me that - I forgot.

...I'm just trying to work out the issues involved with manufacturing before I have to tackle an even more involved project.

Keep an eye on your supplier's Q.C. One XBL^2 driver designer had fits over his suppier - took them months to get the tight XBL^2 tolerances repeatable in their manufacturing process.

i post that here since joecarrow was kinda following me, could give you some ideas

I posted a suggestion that he contact you and put in a vote for a hard cone version.

[Dylan Matlow]

Keep an eye on your supplier's Q.C. One XBL^2 driver designer had fits over his suppier - took them months to get the tight XBL^2 tolerances repeatable in their manufacturing process.

Thanks, really if theres a supplier thats worked out how important the QC aspect is so I don't have to go through that months long headache I might have to give them a call assuming the un-named person is willing to let that information go.

I'm not opposed to polishing surfaces on the really high end stuff thats coming in order to get the tightest fits possible... :-D Never hurts to have those last few microns...

:rofl:

Wonder what the odds are of keeping that degree of QC in line anywhere other than in house (long term goal)...

If anyone out there happens to know a supplier that can handle SiC cones at even a fairly reasonable price I'll be a happy camper... or even AlSiC in the 300 micron thickness range...

I wonder if keronite can be applied to AlSiC, I bet it can...

I've never seen anyone use rohacell between layers of 100-150 micron deep (25% thickness or so on each side) anodized aluminum, that really might not be a bad application...

Any advice on cone profiles for aluminum given I have about 26mm of cone height to work with and there is a phase plug? I really need to look into some of these freebie ME FEA tools a little more seriously...


Oh and Jeff asked for the klippel back from npdang so I'm hoping I can get it run there or if he will be open to loaning it out in the future... otherwise I'm going to be looking for some help from the community, see if theres enough support out there from individuals, administrators, and companies for us to all pitch in a bit and order one for community use. I know if it was housed here I'd be more than happy to measure anything and everything... I just can't stomach paying $400 for a report from the good Dr. himself considering his time is worth so much...

I guess we will see how it goes though... I know I'd much rather pitch in $400 and have some fun equipment to play with :T (I'd be more than happy to pass it around for others to play with too)

[---k---]

I wonder if someone like Kevin over at DIYcable.com would be more interested in distributing these than the big two.

[Hank]

Dylan, one of our electronic projector manufacturers is one of the 3 biggest driver and speaker manufacturers in the world. They're an OEM/ODM and make speakers for some big names in the U.S. and Europe. If you want, I'll ask them what they can do. Send me detailed specs/drawings, material callouts, etc AND quantity- total annual quantity and quantity per shipment. I don't know if they would be interested in your quantities, but I'd be happy to ask.

[cjd]

I've never seen anyone use rohacell between layers of 100-150 micron deep (25% thickness or so on each side) anodized aluminum, that really might not be a bad application...

So I'm not sure what your'e saying, but... when I kicked in an RS-270S-8 I took some time to sorta put it back right. And I was sure that the cone was multiple layers, not a single layer, based on the feedback I got from the aluminum while reshaping it close to normal. I've not cut into the cone to see if I was right, but I do have a number of years under my belt working with metals and such.

C

[Dylan Matlow]

Dylan, one of our electronic projector manufacturers is one of the 3 biggest driver and speaker manufacturers in the world. They're an OEM/ODM and make speakers for some big names in the U.S. and Europe. If you want, I'll ask them what they can do. Send me detailed specs/drawings, material callouts, etc AND quantity- total annual quantity and quantity per shipment. I don't know if they would be interested in your quantities, but I'd be happy to ask.

Thanks
Hopefully they won't mind the 500 unit initial quantity, and I'm not 100% sure what the annual quantity would be but this 2 ohm unit is destined for car audio so I would imagine it would be quite a bit higher volume per year than DIY

I just got a chance to look at the 6.5" in person :-D and well its quite hefty. Xmag > Xsus by a little bit I think still its pretty close.

The surround is a bit on the thick side and given that its one roll the cms curve isn't going to be as symmetrical as I would like... I might just have to tool my own thinner 2 roll surround out of Arnitel... Well I will in the end regardless since it only makes sense to...

The price that I managed to find is going to likely be hard to beat but I'd take extra quality control over a few dollars per unit variable cost... Every dollar spent on prevention is worth 10 in savings down the road they say...

Regardless I'll be needing a small format tweeter before too long here with proper mounting hardware that compares to the seas small format units... Really I think most people would be OK with a medium format external neo magnet (extra $$$) with a small rear chamber although I'll have to do a little more research 2.5" seems fine to most people I talk to for an improvement in quality, thats hardly the masses or retail though... Not to mention I'll need a xover on a PCB after I have a chance to work with the samples some and design it...

Any chance they have ever used SiC or AlSiC cones before? That could be a real order winner for me as well for both projects instead of just the 2 ohm... It doesn't seem like AlSiC would be that hard to work with.

[Hank]

Dylan, send me a message with all your specs/questions, etc and I'll call Taiwan early Monday morning and discuss this, then forward the specs. They will likely have questions, so we'll see...

[Dylan Matlow]

Well the Le vs X looks to be pretty nice at least...
Impedance @ 10khz:
+xsus = 17.28 ohms
0mm = 17.4 ohms
-xsus = 17.45 ohms

I'll get it out for some more detailed measurements this week and I'll have some more time after Wednesday to get to work fixing the cosmetic issues as well as getting a few other projects on track. I get to have fun explaining another lead wire weave technique as well as set up my own measurement system for frequency response.

[biggerrigger]

I joined this site just to follow this thread. I saw no mention to the price of the 480 a/stock drivers that you are trying to get rid of to fund your project. I looked in the pawn shop but did not see any thing. TIA
Aaron

[Hdale85]

Don't think he's allowed to sell them in the pawn shop here. Probably have to send him a private PM.

[biggerrigger]

thanks for the heads up

[Dylan Matlow]

Yea I wouldn't want to step on anyone's toes here.

Well I'm done with finals so I have a bit of time to actually get moving now, I'll let you know how it goes.

[biggerrigger]

Any updates?
Aaron

[Dylan Matlow]

Hey guys, sorry I've been away for awhile. I've been working on prototyping and protecting a new motor technology and a certain distributor is currently evaluating the 6.5" prototype. I think the breakup point is lower than it should be and it needs a diffrent cone...





I will try to keep you more up to date.

[cjd]

Dang that looks fun!