Sal's Dynamic series 4T and 4CC

[aqus]

First of all thank-you to all the people in this DIY and other groups for your help and generosity in helping others and sharing so much information on building speakers.

After lots of research and help from many here I have decided to build Jed's Dynamic series 4T and 4CC center channel.

The reason I chose his design is because I will have my speakers next to my TV which is placed in a corner. I wanted a design preferably which had around an 8 ohm impedance. Can take power if required and had nice dynamics. And weren't too tall.

I have ordered my parts through Jed who was very helpful so far.

I brought my cutlist to a home center to get my MDF cut.

I have include my cutlist if anyone is intrested. If anybody needs the 4T or 4CC individually just ask. But if you do both the one included has less waste.

The woodworking will start this weekend, so pictures and my progress to follow soon.

I work for a counter top and thermoplastic manufacturer, therefore I was thinking of doing my boxes with a formica 9012 laminate and making my baffle with black thermoplastic pvc. The baffle will probably be removable but not decided yet.

to be continued.....

[TacoD]

What is thermoplastic pvc? Is there a difference with normal pvc?

[aqus]

It is used to make kitchen doors. Therefore it is a vinyl sheet that is made to be reheated and molded and a more flexible than PVC.

http://www.belanger-laminates.com/anglais/portes_thermo_ang.htm

The press can only go upto 1-1/4'' thick therefore I can only do the baffle.
Could do all other exterior parts before assembly, but Laminating after assembly is probably easier and a cleaner job.

[Bear]

How does the stiffness compare to MDF at 1.5" thick? The "flexible" property would worry me.

Bill

[aqus]

I am still using MDF, all the thermoplactic is, is a finishing. Instead of painting or veneering I will use thermo. Basically I build the baffle and get it pressed or molded if you prefer with the themo. If I choose a shinny black I can get a piano finish without paint.

[Jed]

I am still using MDF, all the thermoplactic is, is a finishing. Instead of painting or veneering I will use thermo. Basically I build the baffle and get it pressed or molded if you prefer with the themo. If I choose a shinny black I can get a piano finish without paint.

That should look really cool. Isn't that expensive though?

[aqus]

Black will go for something like $6.50 a square foot. So a 8" x 48" baffle should cost approx $18.00. Gloss(piano) black is about $25.00 a baffle. But I work for the company so will get a better deal

[aqus]

Here is all the wood already cut up for the 2 towers and the CC.



Made my first cut for the braces with the jigsaw. Didn't like it so decided to make a jig for my router and cut it with that.
I know it's inside and doesn't show but rather have nice and straight cuts.
Used 1/4" cutting bit, broke 2 and burned another. Supposed to be medium quality, I am a little worried about doing all those driver openings.
I did about 4 passes per opening





here are the finished braces. Lots of burn marks



This is a dry run before assembling



All clamped up



Happy to have got all my braces cut, and first piece clamped together today.
Sunday morning I will assemble the 2nd tower and tomorrow night the center channel, and the 2nd top piece of the towers. Make sure I don't miss the superbowl.

I used some 2" brad nails to hold everything aligned before clamping.

[aqus]

diffraction

I have a question on diffraction I have read up on it but more confused now than before.
For the baffle I will be doing a 1/4" roundover. Being so narrow I can't do more. I guess doing a round over is better than leaving it square?

Also I will be putting grills on my speakers for two reasons. One is people are saying the tangbang mids are very fragile, therefore worried when my wife cleans. Also especially the huge center it will be less in your face with a black cover(It's a wife thing).
So what is the best way to do a grill cover as to avoid diffraction and other issues? I know no grill is best but I can always remove it when doing some serious listening.
Should I use 1/2" MDF and keep it close to the baffle and make a 45 deg chamfer cut in the inside like suggested by Human speakers? Is it better raising it off by a certain distance? Has anyone ever used aluminum door screen frame? It seems light, and there is a groove to insert the cloth. Worried about vibration though..

[ripcard]

About the round over on the baffle...I did a 3/8" on mine and it worked fine. 1/2" seemed like it would leave too little material on the edge of the RS180 holes so I didn't risk it. If you haven't seen it already, you can see my build thread on Jed's board. It's the Mod 2 T build.

[Dennis H]

Mount some felt in the grill so it surrounds the tweeter. 1/2" thick felt if you use 1/2" thick MDF.

[aqus]

felt is needed only around the tweeter?
How wide of felt do you usually need, if you see the dynamic series the mids are very close to the tweeters?

[Jed]

I should have your crossovers out to you this week. Wow, you don't waste any time. The build is looking great!

And this speaker wasn't voiced with felt so it isn't necessary. It might change the tweeter level enough to sound too recessed. Edit: I see now you are talking about a grill. Just leave enough space around the tweeter so it doesn't introduce a sharp edge... and if you do have some sharp edges on the frame of the grill, line that with felt.

Jed

[aqus]

foam

Does the back part of the mid chamber have to be lined with foam. Just noticed if I seal up the box I won't be able to get to the section behind the mids and tweeters. Or should I wait to get the foam lining before closing it up?
Jed I noticed from your pictures you added foam only after it was all closed up and driver holes removed, so I guess you left the part behind the mids to bare MDF, unless you have very long and flexible arms

[Jed]

Does the back part of the mid chamber have to be lined with foam. Just noticed if I seal up the box I won't be able to get to the section behind the mids and tweeters. Or should I wait to get the foam lining before closing it up?
Jed I noticed from your pictures you added foam only after it was all closed up and driver holes removed, so I guess you left the part behind the mids to bare MDF, unless you have very long and flexible arms

The mid chamber itself is lined with 3/4" sonic barrier except for the first few inches- which is 1/2 Sonic Barrier. The midrange enclosure is filled with poly/acousta stuff. The area behind the midrange chamber (part of the woofer enclosure) is filled with Acousta stuff. You can line the back of that with 3/4" foam in addition to the poly if you want.

By the way I mailed out the remainder of your kit today.

[aqus]

weeks work

Here is what I had time to do this week after work.
Slower than I thought, wish I had more clamps.

I glued the side panels and used 2" brad nails to hold it all together before clamping.
For the front side I marked where my braces are and nailed close to there so I don't nail in the middle where I have to cut the opening and ruin a router bit



After closing the boxes all up. They fit pretty nice, I had cut the side panels to exact dimensions and got lucky. I would suggest to oversize a little then trim them down.
I still had to trim a little to make it flush, luckily they were a little longer rather than shorter.



That's it for now. Next step cut out openings in first baffle.

[aqus]

Weekend work

Here is an update on work done during the weekend.
All is measured up.




Made my own router jig after being inspired by some on this site



I was fed up of having the wire and vacuum hose getting in my way so I hung it up



here they are with cutouts all done. Broke another bit so I went to bu a 3/8 upspiral bit with 1/2" shank made by freud. Cost my $40 but what a difference.



Next started installing the laminate. I used spray on contact cement. Used two cans up to the last drop...
screwed up the first one, misaligned and of coarse to late to move. Luckily it is the bottom of the center speaker. Then I did what I should have from the beginning and use sticks to separate the two before contact.

Here they are all done. There is still the plastic film on them, so picture isn't too great.





Now I need to cut the driver hole for the drivers in the baffle. But will wait to get all parts in so I can measure depth.
Do most of you use a straight bit to make the cutout where the driver sits and then cut the rest out to make the whole. Or do you make the hole and then use a rabbeting bit to make the driver groove?

I got to go take a shower I have contact cement fumes in my nose and I am afraid if I pinch my nostrils together they will stick together

[DancesWithBeers]

How are you going to recess the drivers? Most people make one pass with the circle cutting jig to cut the recess, then reduce the diameter and cut out the hole for it to drop through. I suppose you could use a rabbeting bit, but I'd be concerned about the gap if the driver flange was not a standard width.

[aqus]

I think I will be doing one pass for the recess, then smaller diameter to cut off the hole.

[DancesWithBeers]

I guess why I asked is that it looks like the holes were already cut prior to laminating. Do you plan do make the recesses using the laminate to hold the center pin?

[ripcard]

What you're looking at is the holes in the sub baffle. There is another piece of 3/4" MDF that goes on top which is then routed for the driver recess' and holes. The sub baffle is captured by the sides and is opened up as much as possible for good air flow. The top baffle is the full width of the enclosure and glued on top of what you saw in the pics. You can then laminate everything before you cut the driver openings.

You just want to make sure you mark which side is the front after laminating 'cause it's kinda hard to tell after. :E

[aqus]

I am about to cut the outer baffles for the tweeters and mids, how much bigger than the actual dimensions do you make your holes usually. Don't want to cut too tight , but at the same time they are so close together so can't make it too wide.

[ripcard]

I measured the driver flanges with a caliper and added 1/16". That gives 1/32" clearance all around. With all the coats of primer and laquer I put on they fit just snug. If you're not painting, you could go less (if your jig will allow). The Jasper that I used is calibrated in 1/16" increments.

[---k---]

The mid chamber itself is lined with 3/4" sonic barrier except for the first few inches- which is 1/2 Sonic Barrier.

Jed,
I know you experiment and test everything, so I was wondering if you've done any comparison to the 1" thick Sonic Barrier. I've been using it, mainly based on price. 1" looks to me like the best bang/$$.

Also, how much have you experimented with how close the foam can be? I've been holding the 1" foam back about 1.5" and then trying to taper it at a 45 degree. I've never really experimented. Maybe I should.

[Jed]

Jed,
I know you experiment and test everything, so I was wondering if you've done any comparison to the 1" thick Sonic Barrier. I've been using it, mainly based on price. 1" looks to me like the best bang/$$.

Also, how much have you experimented with how close the foam can be? I've been holding the 1" foam back about 1.5" and then trying to taper it at a 45 degree. I've never really experimented. Maybe I should.

I try to leave enough airflow around the drivers with the dampening materials. That's why it is stepped with the 1/2" around the drivers for the first 3 inches or so, then it goes to 3/4". With a narrow cabinet this is necessary. If going wider, as long as there is an inch or so around the cone you are fine.

I've used the 1 1/4" multi layer stuff which is probably the best but it is very expensive.

Zaph mentioned somewhere that when he did some impedance sweeps, the Sonic Barrier didn't appear to reduce the cabinet volume at all, which is another plus in my book.

Sonic Barrier is also consistent- which is nice for me when I sell a kit. It insures the same amount of dampening material is used and that it matches the reference design, which in turn should help come close to how I voiced the originals.

[aqus]

holes galore

Made the recess for all the drivers, think I am dizzy.
Will do the final cutouts this weekend. Got to go work out of town(Ottawa) for a few days. Got to pay these things
For others who want to make this project be careful, you don't have much space between drivers. I am happy nothing overlapped. Two woofers are very close, maybe a millimeter between them. For the center I had to raise the tweeter approx 1/4'' from the original measurements or else it would have overlapped.

For the cutouts do you guys make it as tight as possible trying to cover the whole flange and then make a little groove for the speaker terminals?

[yousuredo2]

One thing I can tell you about doing the final cutouts...
I have learned that it is easier to cut almost all the way(1/16"), and use a razor/etc to cut the rest away...
Saves you from digging in the perfect cut circle
when the last of the material is cut and the router can move freely.

or you can simply put a sacrificial piece of MDF under it to help..

[aqus]

painting baffle

I will be painting my baffles soon. I noticed some people covered up the inside of the holes with newspapers before spraying. Is there a reason for this? My drivers are flush with the baffle, therefore if paint accumulates on the edge where the driver sits and the top of the baffle it will remain flush. And also don't really feel like taping up ALL those holes. Am I missing something here?
They are not glued to the box yet, so getting paint inside the box and foam is not an issue.

In case anybody has been following this thread and asks, I will not be using thermoplastic for my baffles. The spacing between the drivers is too small therefore I am afraid it won't glue well. And because of the pressure of the press there is a chance the baffle will snap.

[---k---]

I stuffed my holes with newspaper just to keep the spray paint off of the Sonic Barrier on the interior. I'm not sure if it was needed, but it wasn't much effort. I didn't bother taping, just stuffed enough for the hole to be fairly well sealed. I'm not sure why others do it.

[aqus]

Weekend update:
Got my holes all cut out, everything seems to fit nicely. For the tweeters I had to do little notches to clear the connectors.
As you can see from the pictures some openings came very close to each other.
If your doing the 4cc check your measurements. I had to raise the tweeter a little higher than the schematics or else it would overlap the mids.

I did a 1/4" roundover on all edges, any more would get too close to openings.



these were close





My first screw up.
I did the recess for the ports. For the center I had precision ports and recess was OK.
For the towers it came with Dayton ports. I took the width of the flange and did the recess. Then noticed I didn't need to recess them since they have a rounded edge. Now they are too deep. Not really a problem, will use some paint on edges and it is in the back.
For the connectors I just did the cutout and will install with no recess.

here is the center port:



And the tower:



Next step is to paint baffles. Tried using some auto primer on a scrap piece which I did the same round over as the baffles and doesn't seem to be drinking much. Primer once dried looks the same on top and edge. Therefore might just use auto primer and paint without using any special sealer on the edges.

I Will probably put some silicone on all interior corners in the mid chamber, to make sure it is air tight. Was going to do the whole box, but figured it would be a waste since it is a ported design, air will flow to the largest opening so even is there is a little leak(which there doesn't seem to be anyways) it shouldn't effect anything. Correct me if I am wrong.

[ripcard]

I will be painting my baffles soon. I noticed some people covered up the inside of the holes with newspapers before spraying. Is there a reason for this? My drivers are flush with the baffle, therefore if paint accumulates on the edge where the driver sits and the top of the baffle it will remain flush. And also don't really feel like taping up ALL those holes. Am I missing something here?
They are not glued to the box yet, so getting paint inside the box and foam is not an issue.

In case anybody has been following this thread and asks, I will not be using thermoplastic for my baffles. The spacing between the drivers is too small therefore I am afraid it won't glue well. And because of the pressure of the press there is a chance the baffle will snap.

You also have a gasket or foam strip to put underneath the frames of the drivers to make them airtight. They will squeeze down to almost nothing when the mounting screws are tightened but, if your driver flange is flush now, you may need the paint buildup on the surface of the baffle to compensate for the foam seal under the driver flange.

[aqus]

Actually the driver is about 1mm deeper, I had compensated for the foam which seems to be approx 1mm thick when compressed. I will be painting the inside also so it will build up with the front of baffle. Also have enough play on sides so paint will make them snug. Boy am I getting anxious now.
Thanks for the heads up

[aqus]

painting

Painting of the baffles is on the way.
I used B-i-n sealer first. First can I bought was defective. After a few seconds of spraying it started squirting from under the valve. Luckily I got it out of the way on time so it didn't splosh all over my work.
Second can worked great

http://www.zinsser.com/product_detail.asp?productid=10

I then painted with a sea black latex paint from Krylon



I decided to use a latex silicone inside the mid chambers and on the outside , just to make sure everything is sealed.

[aqus]

problem

Ok I did a few coats of paint. I noticed on two holes that the edge is not right.
Not sure if it is because of swelling because of the latex paint or maybe the upspiral router bit maybe lifted the MDF a little. Didn't notice it before.
Not sure if I should try sanding it down and risk making it worst or leave it as is.
It isn't that bad, and noticeable in certain angles.
Also other coats of paint I will be putting the pieces in a vertical position to get a better and more even top coat.
Should I sand with 600 grit?

[Jed]

Not really sure how to fix the raised area, but a sanding block and fine grit paper might do the trick if you don't mind respraying.

Keep the pics coming. These are looking great.

[TacoD]

Good work! I agree with Jed, you have to fix this "raised" area by hand using some sandpaper otherwise you always see this "imperfection". And once everything is assembled changes are you don't want to take it again apart.

[aqus]

Thanks that's what I did. I knew it would bug me if I left them like that even though I will be putting a grill on them(I know I know). I did some light sanding using some 600grit and resprayed a few times. Looking good.
Should be gluing the baffles this weekend.

[aqus]

sooooo close.

Last two days put in the sonic barriers. Today I stated gluing the baffles. took some scrap pieces of mdf and cut to fit inside the driver openings and clamped there, so I don't put pressure on the painted surface.
In the meantime soldered up the speaker wire to the crossovers. Used 12ga for input and woofers, and 14ga for mids and tweeters.
The crossovers will be sitting at the bottom of the towers and in the back of the mid chamber in the center channel. I actually managed to put two screws in there by hand so that they don't swing around when transporting.

I filled the back of the mids with polyfill and inside the mid chamber leaving approx 3'' of air space towards the front.

Here are a few photos:

[vinceb]

That swelling looks like it was caused by the water based paint. I had a tiny bit of this on the back port holes of the mini statements where the mdf swelled under the veneer, would have been worse like yours if not veneered. On the front I had primed and painted the driver cutouts prior to veneering (highly recommended) but not on the back mid hole or port cutout. When I dyed the cabs with water based dye (transtint mixed with water) it swelled a tiny bit. I think the lesson here is to prime (bin shellac is awesome on mdf) and paint any raw mdf edges prior to any water based paint/stain/dye/whatever.

Cabinets look great, I like your laminate, very sharp and should be impervious to abuse.

[aqus]

That swelling looks like it was caused by the water based paint. I had a tiny bit of this on the back port holes of the mini statements where the mdf swelled under the veneer, would have been worse like yours if not veneered. On the front I had primed and painted the driver cutouts prior to veneering (highly recommended) but not on the back mid hole or port cutout. When I dyed the cabs with water based dye (transtint mixed with water) it swelled a tiny bit. I think the lesson here is to prime (bin shellac is awesome on mdf) and paint any raw mdf edges prior to any water based paint/stain/dye/whatever.

Cabinets look great, I like your laminate, very sharp and should be impervious to abuse.

Actually I did use bin shellac before using the latex paint. Glad they are much better now. Should be taking the plastic off the boxes by tomorrow.
Getting closer and closer to giving my ears a treat.

[Jed]

Actually I did use bin shellac before using the latex paint. Glad they are much better now. Should be taking the plastic off the boxes by tomorrow.
Getting closer and closer to giving my ears a treat.

The drivers do take some time to really open up.

[aqus]

Just saved $27k

I am finally done.

Didn't add up everything yet but The 2 towers and center cost me approx $3k Canadian. So if usually speakers retail for 10x the cost then these things are worth $30k??? I believe maybe closer to 10k.

Every thing is plugged and soooo happy it all works.(Little nervous about all the soldering and connecting the quick connects was a pain(very tight). bent two speaker spades but luckily none broke.

The mid chamber is stuffed with polyfill from Walmart. Left about 3'' for breathing room. Also stuffed behind midchambers on both the center and towers. For towers put a piece of door screen in opening just to make sure the fill doesn't fall off with time. I bought 2x 4lbs bags and only used approx. half of one. Tried compacting as much as I could.
Had to cut out approx 2'' of sonic barrier on one side of bottom of towers in order for the crossover to fit.
As for sound these speakers are amazing. I know it will just get better as they play, but already I can see their potential. The only thing so far it seems bass is weak, not deep. Maybe it is the corner placement or because I am used to hearing my 15" sub. Together they are great though.

I will post after hearing them for a while. They look so good that I don't feel like making grills for them. Might be one of those projects I will postpone for a while. TV is also a little high, see if I get used to it or else I will build a heavy duty stand to sit the center on top of the screen. This things weigh in at 104 lbs each. 83lbs without drivers.
Thanks for all your help
Oh and BTW. If anyone is thinking of buying kits from Jed of https://web.archive.org/web/20090605...dspeakerdesign
He was a pleasure to deal with. Answered ALL questions in a timely matter and a great support. Great speakers....

[Jed]

Thanks for the great review and you just wait, the bass will come to life after the suspensions of the RS180s break in more. The mids will also open up.

Congrats on a great build. Man you really cranked these things out, too. That was fast!

[Hdale85]

What are you powering them with? Granted mine are in quite a bit more space and possibly tuned a bit lower, they have tons of low end The fact you are used to hearing the 15" sub probably has some to do with it as well. If your powering with a receiver I'd recommend getting a nice power amp (look at Emotiva for very nice cost effective solutions) if you're using a power amp then like Jed said just wait

[Johnloudb]

I'd avoid corner placement if possible. I've possitioned speakers in the corner just the way you've done and it really caused some frequency response problems. The midbass was weak and there seemed to be a peak in the mid highs. Though no harm in trying to see if your situation works out. Congrats on a terrific build, they look great!!!