# MTM-WW build. Noob on a mission...



## captainobvious

Okay, so I've decided to go the MTM route as opposed to Line Array at this time due to the crazy driver cost for the array. Once that tax check rolls in though, I may have to plan out the other one 

The mission is to create a reference MTM plus WW design using these drivers:

*W4-1320SJ *Parts-Express.com:Tang Band W4-1320SJ 4" Bamboo Cone Driver | Tang Band W4-1320SJ bamboo full range driver 4" woofer extended range driver tb speakers line array

*Vifa XT25* Parts-Express.com:Vifa XT25TG30-04 1" Dual Radiator Tweeter | Vifa XT25TG30-04 1" tweeter Dual Concentric Dome Tweeter sonus faber 4 Ohm tweeter vifa vline waveguide ring radiator hf high frequency mtm tymphany09

and filing in the low end, 2 per side:
*Usher 8955A* Parts-Express.com:Usher 8955A 8" Carbon Fiber/Paper Woofer | 8955a 8" woofer 8 inch woofer midbass midwoofer carbon fiber woofer

Center to center driver spacing and offset on the baffle is calculated as is measurement(or listening) location. 


I'm a total rookie when it comes to building a home audio setup so Im going to rely on the wisdom of some of you fellas to help me along the way and steer me in the right direction. I've been playing around with the PCD design tool which can be found here: jbagby
This is pretty kick ass software, and its FREE to boot 
Mainly I have been trying to get a smooth summed frequency response. In my model, the woofers are wired in parallel and the mids in series (and polarity reversed). The Crossover points are:
Woofers: LR2 400hz LPF
Mids: LR2 300hz HPF / LR2 3Khz LPF
Tweeters: LR2 3Khz HPF

You can see the L-Pad and filter types/values listed in the screenshots below. What do you think about the design thus far? Anything stick out that I should be concerned about?

(CLICK on the bar above the photos to enlarge, or set your browser to zoom 150% for a better view)


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## captainobvious

Someone pointed out to me that the tweeter is showing 1 ohm impedance ...Dunno what happened there. I'm going to redo the trace and reload it into the design and see what happens.


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## captainobvious

Well, I worked out a few of the kinks and made a few changes. This latest graph does not include baffle diffraction simulation correction yet as I haven't decided on the baffle dimensions of the enclosure just yet. That should hopefully be coming shortly though...I just need to wrap my head around how I want it to look cosmetically. I did add estimated z-axis dimensions though as required.

I did this graph as an active crossover setup as that is likely what I will end up using. Some of the mindset behind this is that I can make small tweaks on the fly if I feel its necessary after listening, or if something with the setup changes. Also, an active crossover can be setup to be used on several different speakers so if/when I build more sets beyond this, it will allow me to save money on component costs. Audibly, I havent heard a significant difference between active and passive crossovers so that for me is a moot point.

I also changed up the crossover points slightly. The latest revision has them set at 200hz and 2500hz, both at LR4. The midranges and woofers are both wired in parallel, and the midranges have a -2db stepdown in gain to level overall frequency response. Some of this may change after all other factors are considered though. Thus far, this looks like it could be a very nice combination. After some modeling of the woofer enclosure/volume, it looks like the box modeler likes a 30hz tuning with appx 40 liters of airspace for the Usher's. This yields an F3 around 36hz. What I don't know, is if the program is modeling that for ONE driver or two which is what i have in the main page of the simulation. Ive got to think its for a single driver as WinISD was showing closer to 75 liters for a pair.

Anyway, here are the current graphs...any thoughts/comments/suggestions thus far? The total impedance looks too flat. What am I missing here?


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## otis857

Im definately watching your progress here. I had an interest in MTM in a car a while back, but after reading Pat Bateman's thread, Im rethinking that. 

One thing I can say is that I have personally seen a big difference in going active in my home set up. I was building a high end hifi for years around Linn components. I'm using 5140's for L&R duties with Linn 5105 amps. I first went single, then bi-amped, then tri-amped with these and noticed minimal difference in each step. But when I bought the active cards (Linn sells custom active crossover boards for each amp/speaker combo), the difference was AMAZING! THe speakers came to life. They improved in all areas, but the biggest difference was in transient response. The bass got much tighter/punchier and the whole impression was - they got FAST! 

I've heard for years that if you have enough power, you wont notice the difference, but I sure did. THe 5105's put out 200watts into 4 Ohms (5140's are 4 ohm), so going tri-amped, thats a lot of power feeding the passive crossovers. And just going active alone was huge!

As for your baffle design, are you going to go with some sort of rounded design, or maybe a tweeter wave guide like PB was playing with? I enjoy watching those of you here that have a handle on the whole package of audio design, rather than the hackers like me who ride your proverbial coat tails.

Post some pics when you get to hacking some wood.


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## captainobvious

otis857 said:


> As for your baffle design, are you going to go with some sort of rounded design, or maybe a tweeter wave guide like PB was playing with? I enjoy watching those of you here that have a handle on the whole package of audio design, rather than the hackers like me who ride your proverbial coat tails.
> 
> Post some pics when you get to hacking some wood.


Thanks for the support Otis. I'm quite green when it comes to this stuff myself too. I rely heavily on the documentation, tools and advice of some very kind people on a few forums who help (generously) to steer me in the right direction  

As for the enclosure/baffle design...Im not totally certain yet. Im sure at the very least it will be rounded at the edges to aid with diffraction. Id like to build towers that have a different look to them...not so "boxy" and traditional. I want to do something substantial even though its my first build because I want them to look AND sound great. Im going to put a little time into doing some sketch ups of a few ideas and see what works for me. I'll post them up once finished and get some feedback.

On a side note...it looks like the "off" looking summed impedance curve in my charts above is because the program doesnt add any impedance info to that graph when using active filtering. Because all of the drivers will have seperate crossovers and be seperately amplified, there wont be a summed impedance to worry about.

Also as a quick update, I ordered a pair of chip amplifier kits which I'll be building to power these with...at least initially. I'll want to see how they perform as they are not mega powerful amps. The speakers should offer very nice sensitivity though so thats a big bonus. For anyone interested, here is the amplifier kit and build instruction page incase you'd like to check it out. I'll be building (2) 4 channel amplifiers based off of the LM4780 chip.

*Kit:* DIY Chip Amplifier Kits, PCB's, Components and Information.

*Build thread:* Commercial Gainclone kit- building instructions - diyAudio

*Specs on LM4780:* LM4780 / 3886 / 3875 / 1875 Comparison


.


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## captainobvious

Started doing some brainstorming and sketching last night to come up with enclosure designs. I have a side profile that looks really cool, and I think I am getting closer. (Brought the sketch book with me today to work on at lunch time too) Unfortunately, I didn't bring my camera to snap pics yet. I'll try to get something up this evening.

Im also now undecided on if this will execute better as a W-m-t-m-W or as the m-t-m-W-W. Signs so far in design point to the former over the latter. These will be rather large towers. My goal is to have the mid point in the design (the center line of the tweeter) be on the same plane as the listeners ears. This will keep everything more symmetrical and balanced. With this in mind, it could put the height around 60". Not too shabby


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## captainobvious

Piddling around with some design ideas...I kind of like the symmetry in the WmtmW. I sketched these up yesterday. Construction of a rounded, almost bowl shape back would be a challenge, but I think I'm up for it. I love the look of the side profile although the base is still up in the air. I'll try to fine tune it and then do some better sketch ups.


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## captainobvious

I got the parts for the amplifiers and started getting them built. 6 channels total based off of the LM4780 chip. Cool stuff!


A few pics...


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## captainobvious

Waiting for a quote back on the remaining amplifier parts, but it looks like after the two transformers, I'll be putting these into two rackmount cases with heatsinks installed in each one.

A few links for resources in case anyone else is interested...


Enclosures can be found here: 
Par-Metal

Heatsinks here (and on ebay):
Jaycar Electronics - Search results

Copper/Aluminum/Brass, etc metal store:
Online Metal Store | Small Quantity Metal Orders | Metal Cutting, Sales & Shipping | Buy Steel, Aluminum, Copper, Brass, Stainless | Metal Product Guides at OnlineMetals.com

My plan is to put the dual stereo amps in one case for a 4 channel amplifier and the paralleled 2 channel amplifier in the other. Since it will require 2 tranformers and some space for heatsinks, I figured a dual chassis setup would work better.


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## otis857

I like your sketches of the cabinet designs. Im interested in how it comes out. The pics make it look like a monitor, but the size & number of drivers is going to have it probably 32-36 inches tall + stands. Are these going to be MDF/veneer or fiberglass cabinets? I like the sketch of the stand design too. Building your own amps too - sweet.

Great start! Keep up the good work.


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## captainobvious

otis857 said:


> I like your sketches of the cabinet designs. Im interested in how it comes out. The pics make it look like a monitor, but the size & number of drivers is going to have it probably 32-36 inches tall + stands. Are these going to be MDF/veneer or fiberglass cabinets? I like the sketch of the stand design too. Building your own amps too - sweet.
> 
> Great start! Keep up the good work.


Thanks for the support Otis 

Yup, they will be big. The cabinets will actually stand about 60" tall when all is said and done. The tweeters center point will be right at the listening posititon ear level.
As far as construction, the front baffle will be very thick solid wood, perhaps birch. It will need to be thick as it will be contoured (rounded) to meet the sides. The shell will be formed and finished with fiberglass, but I want to be sure it has mass to keep the fs of the cabinet low. I'll have to decide what to use to add mass to that. Ive used lead beads in the fiberglass before to add weight but that could be very expensive for a project of this size so I'm open to suggestions.
I think the base and enclosure should be modular so that I can take it apart for moving if necessary. The bases will have to be heavy as well to anchor the enclosure...I'll most likely use something heavy inside that as well like sand/concrete. These are going to be some heavy, beastly speakers. 

As for the finish...Im undecided. I'll probably think more about that once I see the formed cabinets. I wouldnt mind a solid stained wood baffle and painted smooth shell though.

.


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## captainobvious

This video shows a good way to do a rounded rear enclosure so I may take some pointers from that in construction.


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## otis857

Great video! I dont know if it will work for your application, but upscale boat builders use a process called balsa coring in their fiberglass hulls. That is using balsa wood pieces, usually 1/4 ' thick, end cut (for water containment should the hull get punctured) and sandwiched between layers of glass. This creates an I beam effect to add strength with minimal added weight. 

You might consider a variation of that approach by using a damping type of material in between layers of glass. Im thinking that if you use 1/8" neoprene in between 2 -3 layers on 2 oz mat on each side, you would have a very solid cabinet that wouldnt break your back. And the neoprene plus the shape of the rear & sides of your design would help control cabinet resonance. Cascade sells a fiberglass damping material for in between layers of f/g mat that uses aluminum & paper, but why buy it when you can make it?


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## captainobvious

Interesting idea 

The video gives a good idea for the "framing" portion of the shell, but clearly it wouldnt work for doing straight plybending as the top and bottom curves would be an issue. Once the framing is laid down, a fiberglass matt/resin/damping layer could work well though.


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## HiVi Guy

Cool chip amp. I have built a few LM3886 gainclones. In fact, I am building 2 stereo sets right now. One amp uses two 3875 and the other pair uses the 2875's.

Nice looking drawing.


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## 94VG30DE

Cool idea. I think it was your line array vs mtm thread I was reading a while back, so it's good to see progress  

Just some thoughts in no particular order: 

At 400hz, I'm not sure the height of your Usher woofers is going to matter too much. That being said, the symmetry of your current drawing is pretty sweet looking. Is there anything inherently wrong with WWMMT though (with tweeter on top)? Seems like you can make a rounded top pretty easily that way, and which would allow you to relieve the tweeter of any baffle-step issues from at least 3 sides (top/left/right). Not sure if it would have a significant effect, but I'm just throwing it out there. 

You mention adding mass to the fiberglass portion of the enclosure. Are you intending this for damping or strength purposes, or both? I ask b/c if you want weight and no added dimensional rigidity, you can go something granular and cheap like play sand. If you want strength but no weight, you can go ropes or the balsa layup mentioned above (look for basket-making material like this: Nantucket Basket Wood Stave Material). If you are wanting dimensional rigidity AND weight, I would be thinking something like lead/MLV or strap-steel. Both would probably be fairly cheap and easy to form to the contour.


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## captainobvious

94VG30DE said:


> At 400hz, I'm not sure the height of your Usher woofers is going to matter too much. That being said, the symmetry of your current drawing is pretty sweet looking. Is there anything inherently wrong with WWMMT though (with tweeter on top)? Seems like you can make a rounded top pretty easily that way, and which would allow you to relieve the tweeter of any baffle-step issues from at least 3 sides (top/left/right). Not sure if it would have a significant effect, but I'm just throwing it out there.


I don't know for sure if theres anything inherently wrong with doing it as a wwmmt, but just thinking about it from a driver positioning standpoint, it seems like keeping the midranges as close as possible to the tweeter, and at the same distance would yield more even response than having one twice as far as the other.
It also seems as though I'd get better overall response because all of the drivers will be less vertically off-axis to the listener that way.



94VG30DE said:


> You mention adding mass to the fiberglass portion of the enclosure. Are you intending this for damping or strength purposes, or both? I ask b/c if you want weight and no added dimensional rigidity, you can go something granular and cheap like play sand. If you want strength but no weight, you can go ropes or the balsa layup mentioned above (look for basket-making material like this: Nantucket Basket Wood Stave Material). If you are wanting dimensional rigidity AND weight, I would be thinking something like lead/MLV or strap-steel. Both would probably be fairly cheap and easy to form to the contour.


I was thinking more about it adding mass and as a result, lowering the fs of the enclosure. Im a bit concerned with having this lightweight fiberglass shell and then having it produce a hollow sound as a result. I may be worrying for nothing...not sure.
One thing that should be in my favor though is that I plan to have the midranges/tweeters in seperate enclosures within the shell. Those would be built out of mdf so the fiberglass enclosure wouldnt play any effect on them.

What about using sand IN the fiberglass mix? Would that have any adverse effect on the resin curing? Could be a good simple and cheap way to add some mass.


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## captainobvious

First up...

Construction of the enclosures. 
This is going to easily be the most dificult part of this project. Because I want a more rounded look and its far above my skill level to do it with all wood, Im going to be making the shells out of FG, which will then be attached to a wooden front baffle.

To make the mold, I first start out with a thick insulating foam from **** Depot. Its the pink stuff and its a polystyrene type. The sheets are available in 2'x8'x2" thick pieces which make for quicker work than the usual thin stuff.
My baffle measurements will be appx 12" wide by 44" long by 2" thick. Therefore, I cut out the required number of pieces of the polystyrene foam to get a good 12" thick base ot start from.





































To bond the pieces together I decided to use the 3M High Strength 90 spray adhesive. I should note that this may not be the best solution for use with foams as it did react with the foam, sort of "melting" slightly the spots where it was applied the thickest. Nevertheless, it does do a hell of a job of bonding. Spray both pieces, wait about 90 seconds, then bond them together...repeat.




















I put some weight on them and let them set up for about an hour and they were dried and solid.


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## captainobvious

And finally, todays progress...

Started the work on the shaping of the shell. My weapons of choice- A coarse grain sanding block, a handsaw and a hand shaver/grater thingy. (Yes, thats the technical term)











































































Now all I have to do is build the mast and I can sail away 


The shape looks pretty cool. The gaping craters you see are a result of the spray adhesive getting cheeky with the foam. Its ok though as I plan on having to smooth the foam out with a filler and do some sanding anyways.

What do you all think of the shape as it stands? More rounding needed? Look a little too boxy still?

One thing Ive been considering is the mounting options and connection location of these guys. Since I want to build a base to support these, I plan on leaving a portion of the very back of the shell completely flat. This will then be the location where I mount the support plate and connect to the stand as well as being the location for the binding post connections and port holes.


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## otis857

Looking good so far. I like using the foam insulation panels for molds. Originally, I thought you would use pour foam, but that looks much easier. I do like the original design better with the bigger arch in the back and more taper on the sides, but hey, its your project. Carry on!! You will inspire us all.


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## 94VG30DE

Cool! that hand grater/shaper thingy looks like it did a great job of shaping those edges. I am actually amazed you didn't have more chips out of the edges, knowing the adhesive ate instead of bonded to some degree. That worked way better than I would have anticipated. 

As long as you are planning on a decent back mounting plate reinforcement, I don't think that flat section in the back needs to be more than 2" wide. Which means you can continue to smooth it quite a bit to hopefully remove diffraction if you want.


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## captainobvious

Thaks fellas. I agree. Still needs more honing. I want it much rounder than that so Im going to keep at it...


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## Boostedrex

Glad to know that the foam "plug" idea is working out for you Steve. Rock on pimpin'!!


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## captainobvious

Yup, good call Zach.

Okay guys, since basketball was cancelled due to the snowy chit out there...got some more work done on the shell mold. MUCH more pleased with it now. Took about 2 hours of shaving and sanding...not fun. 

Thoughts ?


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## otis857

Now you be a stylin!! Have you figured out how you're going to make the stands?


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## captainobvious

otis857 said:


> Now you be a stylin!! Have you figured out how you're going to make the stands?



Havent given that part a whole lot of thought yet, honestly. It will join the shell with a strong plate of either wood or metal at the back, and be bolted through the shell. I may end up just making another mold for the base, and then doing either wood/metal/carbonfiber reinforced fiberglass, extra thick with the remaining interior volume filled with sand.


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## habagat

Wow! looks like a great build in progress! Any plans on going full active xovers? Behringer has a really nice xover with time alignment to boot! tA might come in handy considering there are 10 drivers, it seems like a really powerful tool.
I know of at least a couple of highly regarded speakers that use it.
Regarding your enclosure, it would be good to make your baffle extra stiff on the vertical plane because it is being supported from the rear only and all the weight will bear upon the baffle and the area of support, I think this could create significant tension and could cause the speaker to vibrate when the woofers move which could diffuse the sound somewhat. Of course just my 2 cents worth I cant wait to see the end result!


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## captainobvious

habagat said:


> Wow! looks like a great build in progress! Any plans on going full active xovers? Behringer has a really nice xover with time alignment to boot! tA might come in handy considering there are 10 drivers, it seems like a really powerful tool.
> I know of at least a couple of highly regarded speakers that use it.
> Regarding your enclosure, it would be good to make your baffle extra stiff on the vertical plane because it is being supported from the rear only and all the weight will bear upon the baffle and the area of support, I think this could create significant tension and could cause the speaker to vibrate when the woofers move which could diffuse the sound somewhat. Of course just my 2 cents worth I cant wait to see the end result!


Yeah, my plan is actually to use the Behringer DCX2496 for active filtering. 
As far as T/A goes, I dont think any will be necessary. 

The front baffle will be 1.5-2" thick so it will be plenty stiff. The shell will be about 3/8"+ fiberglass composite, so its going to be extremely rigid, especially with the curved construction. I think this thing will be VERY solid when complete.


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## habagat

captainobvious said:


> Yeah, my plan is actually to use the Behringer DCX2496 for active filtering.
> As far as T/A goes, I dont think any will be necessary.
> 
> The front baffle will be 1.5-2" thick so it will be plenty stiff. The shell will be about 3/8"+ fiberglass composite, so its going to be extremely rigid, especially with the curved construction. I think this thing will be VERY solid when complete.


 Thats the exact model I had in mind!:laugh:. The TA feature might still come in handy, All the drivers are mounted on a single plane. The sound emanating from a deep woofer would be a tad later than a shallower mid and even later than a flush mounted a tweeter. I have heard speakers that have adressed this issue and they sound phenomenal! Just my .02 worth.


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## 94VG30DE

habagat said:


> Thats the exact model I had in mind!:laugh:. The TA feature might still come in handy, All the drivers are mounted on a single plane. The sound emanating from a deep woofer would be a tad later than a shallower mid and even later than a flush mounted a tweeter. I have heard speakers that have adressed this issue and they sound phenomenal! Just my .02 worth.


Speed of sound is 13397.24 in/s. Assume that the furthest woofer is back-mounted 2 inches into the enclosure, which is probably much more than normal. If my math is correct, that means that the max difference in arrival time between the woofer that's 2" recessed and the tweeter that is flush mounted is 0.000149 seconds (0.149 milliseconds). I don't think the T/A knob is that sensitive, and I doubt my ears are that sensitive.


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## captainobvious

Plus, I will try to align them acoustically as best as possible to minimize and differences in arrival times. 

But, I do see your point.


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## habagat

94VG30DE said:


> Speed of sound is 13397.24 in/s. Assume that the furthest woofer is back-mounted 2 inches into the enclosure, which is probably much more than normal. If my math is correct, that means that the max difference in arrival time between the woofer that's 2" recessed and the tweeter that is flush mounted is 0.000149 seconds (0.149 milliseconds). I don't think the T/A knob is that sensitive, and I doubt my ears are that sensitive.


 The information I offer the op is based on personal experience and not conjecture nor assumptions. It holds true for me because I do hear a difference. And it is inconsequential to me if one chooses to believe it or not.
Admittedly I believe that physical time alignment would be more desirable than electronic manipulation. The apparent physical depth of the driver is not necessarily the acoustical center of the driver, and it would be good to do a test baffle to get it right. And again its just my .02 worth based on my experience.


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## captainobvious

It is definitely a plus to have the option there if necessary. Thanks for your input. 

I'll be ASSuming that the point where the cone meets dustcap will be the acoustic center of the drivers and thats probably about as close as I will be able to determine it with the minimal resources available. Im sure there are some software tools I could use since I have the ECM8000 mic and TrueRTA software on the laptop, Im just too green in that respect to know the proper way to do it.


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## captainobvious




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## ryan s

Honey Comb cereal!!!!!!!! :laugh:


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## captainobvious

LOL

I knew someone would catch that! Honeycombs...mmmmmmm


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## otis857

Ready for Glass, YA! 

Back to the physical time alignment questions, that seems like the subject of many debates in the high end hi fi speaker market as well. I remember Theil speakers used sloped back front baffles for that reason, yet other mega buck speakers did not. I haven't followed Hi Fi in a while now (cant afford to) so I have no idea what the current thinking is. But it seems to me that if you recess the tweeter very much, with the mids being that close, you end up with a quasi wave guide. Which is OK if that's in your design. It may actually enhance the MTM concept of reducing vertical dispersion.


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## habagat

looking good!


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## captainobvious

Uh Oh...


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## captainobvious

The new plan:

Building with wood/mdf for this one. The design is based off of Dan Neubec's "blades" as his enclosures look super cool. These are modified for my drivers and tastes. But you can get the idea...





























AVI 3d view:






.


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## otis857

Looks interesting. You didnt think you could salvage your original design, or did it not look as cool as you pictured it in you head? Ive done that.


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## 94VG30DE

otis857 said:


> Looks interesting. You didnt think you could salvage your original design, or did it not look as cool as you pictured it in you head? Ive done that.


Curious about this as well. I saw the result of the tape/resin combo, but I figured you might be able to save it with some body filler or something.


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## captainobvious

For two reasons...

It was fubar after the fiberglassing.

It wasnt going to net enough internal volume to tune the bass drivers as I wanted.



So, I decided I may as well go a different route and have some fun with the new router! 
My amplifiers are about 50% complete and I will be ready to start building the speakers shortly. I just need to come up with a blueprint of all dimensions and measurments for the cabinets and then get cracking. I'll update with progress....


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## captainobvious

I'll likely end up building the white and black enclosures above, but with the wood and black finish. (2) 8" bass drivers per cabinet should be plenty of low end without needing the 12" sub which is seen in the larger version.


Here is a quick update on the amplifiers...
Got some more work done last night. This is moving slowly as I only get a little time here and there to work on it. But Its starting to come together for sure. These things are gonna weigh a ton. The transformer and heatsink alone are probably 15+ lbs. 


Oh, and the woman is NOT happy about the current state of the dining room table lol


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## captainobvious

Found a few hours to continue working on the first amp yesterday...Its pretty much ready for intial testing with the digital MM. I'll hopefully have a little time later today to do that and see where its at. Hopefully I didnt screw anything up.

When cutting out the hole for the power module, I went a little too big so it left some gaps around the edges...oddly enough they dont supply any sort of cutout template for these. Anyway, I ended up wasting about 40 minutes fixing that mistake by cutting out a piece of black lexan and hand filing it to fit, and round edges. You'll see it in pics below. Came out pretty well I think. Got the rectifer board wired up and mounted to the enclosure side wall close to the transformer. You'll notice that I installed a 4 position terminal strip to be an in-between for the rectifer/power supply board and the transformer's secondaries. The reason for this is that the secondaries wire guage was much too thick to use the pcb board holes. I didnt want to risk drilling them wider, so here we are. Looks neat and should work well methinks. I havent mounted the front aluminum panel yet because I dont want to marr it, but the stereo gain knobs are ready to go as well.

Some pics...










In this pic, the Live wire is not connected yet as this will go through a lightbulb for testing first. This is supposed to reduce risk of damage to components if miswired, etc.


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## captainobvious

And thats where Im at up to this point.


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## Avernier

what are the expected specs on those amps when your done?


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## captainobvious

Avernier said:


> what are the expected specs on those amps when your done?


About 60wpc RMS on the 4 channel amp and about 120wpc RMS on the 2 channel.

THD and noise are extremely low, good channel seperation, etc.

I tested it briefly yesterday and it definitely has enough power to do what I'll be asking of them. Very clean!


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## Avernier

beastly. i like it.


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## otis857

Hey Captain, Hows your project going?


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## tyort1

Those look amazing!


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## captainobvious

otis857 said:


> Hey Captain, Hows your project going?


Sorry for the delay...here's the latest: My (in progress) project *pics too* - Techtalk at Parts-Express.com

Ive started building the new cabinets


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## captainobvious

Since seeing Dan's 'blades' I had been itching to build a pair of speakers with the same (or very similar look at least), but with different 'guts'. I just love the lines and the hard edged look of them (well done Dan!) I've had my drivers ordered and sitting in the basement for months and it's about time I finally got this project going.

This (when completed) will be my first home speaker build. A bit ambitious? Yeah, you could say that. Even I'm a little intimidated...
I've tinkered around in the car audio realm, but I have very little wood working skill. For me, jumping right into the fire has always been the best way to learn. It's very impressive seeing some of the high quality work that you DIY'ers are pumping out. Both technically, and in terms of craftsmanship. There's alot for me to learn here from you fellas 

Anyway...on to the specifics...

The build is an MTMWW configuration utilizing the following drivers:

Vifa XT25TG30
Tang Band W4-1320SJ
Usher 8955A

I chose the xt25 for its good smooth extended frequency response. The W4's I have used before (both W3 and W4 version) and I'm a big fan of the way these bamboo/paper cones produce vocals. The 8955A's were chosen for their low distortion and ability to play low. I could have gone cheaper, using the 10" Dayton drivers (I actually have 2 sitting here as well to play with), but I've been wanting to try the Ushers for a while so I figured what the heck.

These speakers will be actively crossed over using a Behringer DCX2496 and powered by 6 seperate channels via gainclone amplifiers that I am in the process of building. I decided to go this route because I love the flexibility of the active crossover and the ability to tweak on the fly without having to stock a ton of crossover parts. That, and I'll probably be building more projects down the road so shared use is a plus.
The Base cabinets will house a pair of 8955a's each with a shared airspace and will be vented. The Mids will share airspace and will be sealed.

I plan on adding bracing to the base cabinets, fear not! 


I started measuring and cutting panels about 2 weeks ago and have been continuing on slowly since then. Im focusing on getting the base cabinets glued up and then I'm moving on to the top. The angle cuts are very challenging with my tools and experience but Im getting there (after some screwups) by being patient and trying some different cutting methods.
The end result, Im hoping will look like this:












*Progress pics:*






























The top panels are simply sitting on top to give an idea of look/shape.


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## captainobvious

Update:

Progress is slow, but it's moving along. Cut a few more pieces and glued together the pieces for the top wedge front baffles. Still have to do the bass bin baffles, rear wedge, bracing, bondo any gaps and then sand smooth.

The pieces you see inside the bass bin are the sides for the rear wedge.


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## otis857

Nice work! Are you going to vent out of the back or front of the bass cabinets? And how are you figuring port size and length with 2 woofers in the same box (newb question)?

I cant say enough about going active on a Home stereo. While not a DIY system, I got the high end bug many years ago and got hooked on the Linn sound. I shot my wad at the time and bought a set of 5140's with a matching 5120 center channel. They are powered by 3 5105 amps for L&R and an older LK100 for the center. 

Out of the box with passive crossovers, they sounded nice. But when I finally sprung for the active crossover cards, the system came to life in no small way! The transients really snap now. The low level detail was greatly improved and the midrange is just magical. Granted, the dedicated crossover cards matched to the amps and speakers makes the tuning process minimal and does get you the best results you can get from the combination. But what an improvement active amplification makes and doing your own tuning with the Behringer should add some real fun to the final outcome of your project. Kudos on building your own amps too, very impressive. 

Im enjoying watching your progress in this endeavor. Keep us posted as you continue. Im hoping to try something like this down the road with my even lower wood working skills, when budget, time and other priority projects permitting . Now its your work that's doing the inspiring.


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## captainobvious

otis857 said:


> Nice work! Are you going to vent out of the back or front of the bass cabinets? And how are you figuring port size and length with 2 woofers in the same box (newb question)?
> 
> Kudos on building your own amps too, very impressive.
> 
> Im enjoying watching your progress in this endeavor. Keep us posted as you continue. Im hoping to try something like this down the road with my even lower wood working skills, when budget, time and other priority projects permitting . Now its your work that's doing the inspiring.


Thanks for the kind words Otis. I plan to use a 4" flared port tube to vent out the back of the cabinets, keeping the front looking a bit cleaner. I'll have around 2.5 cubic feet or so of airspace after driver displacement and bracing, and before adding any internal stuffing or foam. I ordered a new flush trim router bit that has the cutting depth I need for flushing up the front baffles to the cabinets and preparing for the 45 degree cuts. 
Here are a few more pics of the latest work which was to add some internal dowels for bracing and adding an additional .75" thickness around the mounting surface for where the baffles will meet the cabinet front. I figure this will make it just that bit more secure with the extra surface area. The additional .75" thick pieces only go about 2.5" deep into the cabinet (not all the way) so its not taking up much volume. As others have inquired, the reason why the braces are set back a bit in the cabinet is to avoid any clearance issues with the mounting of the bass drivers. Once my bit gets here I'll be able to make a good push on these things. My worry then will be cutting out the driver recesses... :surprised:


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## captainobvious

Just a minor update. I recieved my Katana flush mount bit for the router and went ahead and flushed up the cabinets, then sanded. They are now ready for the baffles. I need to mount the baffles, flush them to the outside of the cabinet and then cut the 45 degree angles. Fun stuff.

In these pictures you can see what I was explaining in my last post. The extra 0.75" pieces around the front of the inside for a larger area of contact for mounting the front baffles...


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## otis857

Nice! Those are going to weigh a ton when you're done.


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## captainobvious

otis857 said:


> Nice! Those are going to weigh a ton when you're done.


For sure! 


Been a while since I've had a chance to work on these...holidays and all..
Not to mention the very cold weather out here in PA 

Anyway just a small update. I checked out the page with a guide for cutting out driver recesses for truncated frames and got the template made and tested for the Tang Band W4 drivers. This project is the first time I've used my new router (or any router for that matter!) and Im pretty impressed with the Hitachi. Not the quietest thing, but not terribly noisy either. Plenty of power for cuts and easy to use with all of the different attachments and depth guides. I ordered a set of the brass guides from MLCS and then realized that this router came packaged with a set of its own- doh! If someone needs a set, PM me.

On another note, I just picked up my prepro for use with the home system. Its a Sunfire Theater Grand. Got some time to test it out with my friends Martin Logans last night and it sounds quite good. Balanced XLR outs for the DCX2496 are a nice bonus and should keep things nice and quiet.

A quick pic for you of the template is below. I expect to get cracking on the cutouts and angle cuts on the front baffles this weekend. Now that I have all this great gear sitting here I need to get off my bum and get to work ! 










And a few more pics I didnt upload yet. The closeup one I took after using the flush trim bit. Nice!


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## captainobvious

Well a few updates...

After doing some testing with both the Vifa XT25 and the LCY110 ribbons, I've decided to run the LCY's. More just a personal taste thing as both sounded excellent, just different "flavors" if you will. Plus I felt that the LCY's had nicer off-axis response which I'd prefer in my room.

Got some work done on the MTM baffles tonight. Recesses and cutouts done. They need a little touch up in a few spots, but not too bad for a first timer, I think. Also need to chamfer/cove the rear of the plates but my toes and hands are frozen so it'll have to wait until tomorrow or Friday. Haven't done the woofer panel cutouts yet but those should be an absolute breeze compared to these so I'm not too worried there. A few pics are below (a few minutes with a razor blade and some sand paper and these should be pretty decent)


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## captainobvious

Well, got some more work done, but also made some more work for myself by screwing up  

I tapped and glued in the hurricane nuts, did the driver recesses and cutouts for the remaining panels and cut the 45 degree angles on the baffles. Did some chamfering of the rear of the baffles as well. Problem is, i had a little mishap on one of the panels and a few nicks on some of the others (I think my buddy's table saw needs a new blade). All in all though, I think they are all useable. I brought out the body filler to get started on them. (I was going to need to do a little spot work anyways to make sure things are smooth). Using Rage Gold filler. If you havent yet, it is VASTLY superior to Bondo in that it is easier to spread and mix, and sands sooo much easier. Of course, its more expensive, but a little goes a long way and the reduced sanding time/effort is worth it alone, to me.

Anyway, a few pics...


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## captainobvious




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## captainobvious

First round of sanding is done. Looks like these will smooth out just fine. I like to mark the areas before applying the filler as you only have so much time before it starts to cure so working quickly is a must. About 5 minutes of work time to spread and apply so its best to mix up small batches.

Second round of filler is now applied.

A few quick pics...


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## m R g S r

wow! thats a lot of dedication! keep up the good work they are coming out great!


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## captainobvious

m R g S r said:


> wow! thats a lot of dedication! keep up the good work they are coming out great!


Thanks bud

Slow and steady progress...
I had a lull over the holidays where I didnt do anything on them as I was a little intimidated about doing the baffle recesses and cuts, but now that Im passed that point, Im making some headway. I should *hopefully* have these ready to go for finishing (veneer and paint) within 2 weeks. I have the cabinet wiring, acoustic stuffing, and installation of the binding posts to do after the rest of this sanding and spot filler work. And of course gluing the front baffles onto the enclosures :blush:


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## captainobvious

Final sanding is done on the baffles. They came out pretty smooth so the "oops" marks shouldnt be an issue. Next up, the spot touch up/fill/sand on the cabinets.


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## captainobvious

A little more progress and a few pics. Got the Woofer baffles done and ready to go, with hurricane nuts. Loaded up the woofer cabinets with some acoustic treatment- 3 diferent types of foam and some fiberfill stuffing yet to go in. I'll be drilling the holes for the binding posts and getting some wiring done here shortly. Also, I'll do the same for the MTM cabinets.


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## captainobvious




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## m R g S r

theyre gunna look mean!


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## captainobvious

m R g S r said:


> theyre gunna look mean!


Hell yeah! They're gonna sound mean too


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## captainobvious

Drilled the holes for the binding posts after veneering the back panel and started glue up of the front baffles...


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## MaXaZoR

Wow...really nice


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## captainobvious

MaXaZoR said:


> Wow...really nice


Thanks Max, getting there a piece at a time 

With this cold weather, working in the garage sucks. Luckily, *most* of the outside work is nearly complete. Im very close to being ready for the veneering and finishing...


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## captainobvious

Started veneering...
I had to fix a little gap between the top edge of the baffle and the top of the bass enclosure. Wasnt quite even and it would have caused issues with the veneer so out came the body filler and sandpaper again. Got the edge damn near perfect with a couple coats and a good amount of sanding. went ahead and applied veneer to the backs, sides and front chamfered edges this weekend. The fronts will be next (should be challenging with cutting out the speaker holes) followed by the tops. Havent decided yet if I'll veneer the bottoms...I have enough veneer , but they'll never really be seen, so...not sure yet. I've had a few issues with some cracking, but I plan on using some wood filler for those spots. I need to test it out first on some scrap along with the stain to see which of the 2 color versions of filler will work best. Anyway...onto the pics...





































The repair job:


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## captainobvious




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## captainobvious

Sad to report...but more issues. So when I did the driver recesses for the Usher 8955a's, I didnt get a clean round cutout, and the recesses were too deep. When I initially test fitted I figured it was something I could live with, but after looking again now that the baffles are mounted...nope 

I thought about it for a bit and came up with a neat way to fix it.
So...the solution? I used some veneer edge banding I had laying around and applied it to the inside cutout. I then cut some 3/4" pieces of drinking straw out and screwed the fasteners in enough to hold them in place. The reason for this was to prevent the filler from getting in the existing holes I had prepped for mounting. After that, it was on to filling the 'trenches' with some rage gold. Definitely a sloppy application, but what can you do...
I just had to be careful not to slop up the veneer I already applied.

Some pics of the prep and some pics coming soon with the result. My plan at this point is to just get a clean edge all the way to the driver cutout diameter and just surface mount them. Theres no reason why I really need to flush them in anyways, so that was the decision.


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## captainobvious

And here's the result...Totally smooth and flush and ready for veneer and drivers!


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## captainobvious

Got the MTM baffles glued up yesterday and started sanding the enclosures. (Also routed the back chamfers for the mids much deeper before doing so) I'll need to do some filling and sanding to get them where I want and then they'll need to be sealed and sanded more. Since they are getting painted, there will be lots of sanding done to ensure a smooth finish.


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## captainobvious

Just a quick update...I finished up applying the veneering and also did a bit of prep and filling on the mtm enclosures. Just a bit more work on those and they will be ready for sealing/sanding and paint. I have had some cracking/splitting in spots with the veneer which I kind of expected being that its raw wood and its my first time. I think I can make these look pretty good nonetheless with a little wood filler and sanding before the prestain conditioner and stain/finishing. We'll see how it goes 

And a couple of pics:


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## captainobvious

...and done.


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## MaXaZoR

Wow...how do I order myself a pair??


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## hybridspl

Those look great, they remind me of Watt-Puppies and probably sound nearly as good, without the $30,000 price tag.


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## MaXaZoR

Where's the review on how they sound??


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## otis857

Yeah, Im curious about that too. Great looking speakers. Well done.


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## captainobvious

Hahaha, thanks fellas. Sorry for the delay. I hadnt seen a response to the "finished" post for quite a while so I hadnt checked back. They sound pretty damn good in my opinion. Even without a sub, those Usher 8955A's have the ability to dig pretty deep. The combination of the LCY ribbons and Tang Band bamboo cones sings a sweet vocal harmony. Overall, Im very happy with their performance.


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## otis857

Glad to hear it. What did you think of the sound stage of the MTMs? Did the 2 mids significantly limit the height of the stage and cieling/floor reflections, or was it not really noticeable to us mere mortals? I had some narcissistic forum nazi here a while back tell me that MTM's are so bad that they are virtually "unlistenable". I guess that's why so many high end speaker manufacturers sell them???


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## Boostedrex

captainobvious said:


> Hahaha, thanks fellas. Sorry for the delay. I hadnt seen a response to the "finished" post for quite a while so I hadnt checked back. They sound pretty damn good in my opinion. Even without a sub, those Usher 8955A's have the ability to dig pretty deep. The combination of the LCY ribbons and Tang Band bamboo cones sings a sweet vocal harmony. Overall, Im very happy with their performance.


Holy hell, you're still alive!?!  Those towers look great man!! I've been putting a lot of thought into some Usher drivers lately. Really clean work and way to stick with the project. 

How did those home brew amps turn out?


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## captainobvious

Boostedrex said:


> Holy hell, you're still alive!?!  Those towers look great man!! I've been putting a lot of thought into some Usher drivers lately. Really clean work and way to stick with the project.
> 
> How did those home brew amps turn out?



Sorry for the delay...it's been quite a while since Ive been on any of the audio forums. The gainclone amps are terrific and have more than enough power to push the mids and tweeters. Plenty clean too 

I never got around to building the second amp for the woofers as I was using a premade unit for those which does the job just fine. Was a great experience doing the work to build both and it's a testamanet that if you stay motivated, you can get a big project like this done. There was more than enough support from all of the forum guys to help with any issues or questions along the way and Im really happy with the end result, especially considering it was my first home speaker/amp build.


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## atxtrd

Nice work! Nice user name too, is that a Joe Rogan reference? I bought my neighbor a mtm kit as a xmas gift and hope to help build them soon, he's been busy building car stuff lately. I've been drooling over the Usher drivers on PE myself, I'd love to build a set of beast towers with dual 8"s in them. If that is your first build you should be proud, killer job!


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## captainobvious

atxtrd said:


> Nice work! Nice user name too, is that a Joe Rogan reference? I bought my neighbor a mtm kit as a xmas gift and hope to help build them soon, he's been busy building car stuff lately. I've been drooling over the Usher drivers on PE myself, I'd love to build a set of beast towers with dual 8"s in them. If that is your first build you should be proud, killer job!


Thanks alot! Yeah, this was my first home speaker build. I definitely learned alot and did quite a bit of "first time" stuff on the project, including veneering and staining...painting with pro auto paint and compressor...just alot of new experience which was cool. The Usher drivers are fantastic and I'd highly recommend them. Wish I could get a set in my doors


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