New DIY MTM Towers designed by Dennis Murphy and Paul Kittinger

[skyline_123]

Sean
Also, is that 0.5" or 0.75" thick plywood?

I used 0.75" plywood. I think you could use 0.5" but I'm fastening the drivers to the front baffle only, so I wanted used a thicker piece.

 

[Swerd]

Thanks, 7" or 8" radius for that curve will do. The front baffle of the STs was exactly what I was thinking of too.

Sean, keep the photos coming. They are great entertainment, even while I'm at beautiful Lake Placid. Yesterday, our 1st full day here, it rained on and off most of the day, so we explored the town on foot and got our bearings. Looked for restaraunts and interesting places to visit. We ate dinner at a good Italian place called Milano North.

Early this morning Mirror Lake, outside our hotel room was gorgeous! I think there'll be no rain today. We'll look for the Marina where I'm told they have 1-2 hour boat tours of Lake Placid.

This morning I was imagining building the ER18 speakers, and I thought to mention that when you rout out the flush mount for the drivers, you have to go a tiny bit deeper than the depth of the driver flange alone. Include depth for a way to seal the driver to the baffle. Some drivers come with a compressible gasket already on the frame and others don't. It is important to mount all the drivers so there is no air leak. What have you got?

You can buy closed-cell foam weather stripping at hardware stores (PE also sells some) that has a stick-on backing. As you tighten the mounting screws, it compresses between the driver frame and the front baffle, but it won't compress to zero. So when you rout out the opening, include space for that.

 

[sawzalot]

I used 0.75" plywood. I think you could use 0.5" but I'm fastening the drivers to the front baffle only, so I wanted used a thicker piece.

How will you fasten the drivers to one single layer of 3/4 inch ply, nuts and bolts with a larger hole in the mdf for clearance or shorter wood screws, I am very curious about this and also how the baffle will get fastened to the mdf?. I would also like to ask how the edges will be finished on that 3/4 inch ply wood baffle, thanks sawz.

 

[highfigh]

How will you fasten the drivers to one single layer of 3/4 inch ply, nuts and bolts with a larger hole in the mdf for clearance or shorter wood screws, I am very curious about this and also how the baffle will get fastened to the mdf?. I would also like to ask how the edges will be finished on that 3/4 inch ply wood baffle, thanks sawz.

Screws work fine- just pre-drill them, but I would use pan-head sheet metal screws. They have thread all the way to the shoulder of the head, unlike wood screws, which have a plain shank. For the baffle, screws work well but again, pre-drill so the sides don't split. If the baffle is inset, fastening from the sides/top/bottom will be a very strong joint. If you can, rabbet joints add glue surface and strength.

 

[sawzalot]

Screws work fine- just pre-drill them, but I would use pan-head sheet metal screws. They have thread all the way to the shoulder of the head, unlike wood screws, which have a plain shank. For the baffle, screws work well but again, pre-drill so the sides don't split. If the baffle is inset, fastening from the sides/top/bottom will be a very strong joint. If you can, rabbet joints add glue surface and strength.

I was under the impression that the front baffle would be out proud of the sides by 3/4 of an inch since that ply baffle will be fastened to the mdf front and the drivers installed in to the ply baffle , am I wrong about that part of the design??
Will the mdf front be recessed to allow the ply baffle a flush finish with the sides ??

 

[Swerd]

How will you fasten the drivers to one single layer of 3/4 inch ply, nuts and bolts with a larger hole in the mdf for clearance or shorter wood screws, I am very curious about this and also how the baffle will get fastened to the mdf?. I would also like to ask how the edges will be finished on that 3/4 inch ply wood baffle, thanks sawz.

I would do it like highfigh said. Use black pan head sheet metal type screws. Parts Express sells both #6 and #8 3/4" pan head screws. Pre-drill the holes and drive the screws carefully. No slipsies allowed with a phillips head screw driver near woofers! If you hunt around you can find similar screws with a square drive head. They don't slip as easily as phillips head.

I imagined the front baffle as standing proud on front of the rest of the front of the cabinet, similar to the way Salk does it, and painted black. This requires a rounded over edge. With plywood, the edges will have to be sealed before painting. I would prime the edges with a 50/50 mix of wood glue and water, painted on in several layers.

 

[skyline_123]

This morning I was imagining building the ER18 speakers, and I thought to mention that when you rout out the flush mount for the drivers, you have to go a tiny bit deeper than the depth of the driver flange alone. Include depth for a way to seal the driver to the baffle. Some drivers come with a compressible gasket already on the frame and others don't. It is important to mount all the drivers so there is no air leak. What have you got?

You can buy closed-cell foam weather stripping at hardware stores (PE also sells some) that has a stick-on backing. As you tighten the mounting screws, it compresses between the driver frame and the front baffle, but it won't compress to zero. So when you rout out the opening, include space for that.

I'm very jealous btw that you're on vacation and rest of us are not.

I did route the hole a little deeper but honestly, unless I can find some thin foam, I think the drivers may be sticking out slightly. That's okay though, if I were a perfectionist, I would have gone to Salk himself and order the ST's . The ribbon does have some nice foam already on there but the others do not.

No slipsies allowed with a phillips head screw driver near woofers! If you hunt around you can find similar screws with a square drive head. They don't slip as easily as phillips head.

This may seem silly but it is very easy to slip up.....er... so I hear. I'm not speaking from...uh...personal experience or anything. Not to worry though, I did not slip up on these speakers, just my old ones .

I imagined the front baffle as standing proud on front of the rest of the front of the cabinet, similar to the way Salk does it, and painted black. This requires a rounded over edge. With plywood, the edges will have to be sealed before painting. I would prime the edges with a 50/50 mix of wood glue and water, painted on in several layers.

If you do not want to use a glue mixture, you can give it a coat of primer and sand afterwards with 200-400 grit sandpaper. A second coat of primer should then seal the deal.


Well, sorry it's been so long since the last time I posted pictures. It's been very busy over here.

Last week sometime, I was waiting for some crossover components that were on back order, as well as the drivers. I really wanted to do something different this time and totally finish the enclosures before assembling the speaker, something I did not do on my last builds. But, curiosity got the best of me when the drivers and inductors came in the mail the same day. I stayed up until midnight assembling the speakers and was so excited, I left out the stuffing and fired them up. After about 2:00am, I realized that I still have to work the next morning and that my poor, sick wife was still trying to sleep. So as they sit now, the baffles need trimming, the drivers need foam to get a good seal, pillow stuffing needs to be added and the enclosures need some paint. The problem is I still can't stop listening. I'll get to the listening impressions later (when I can scrape my jaw off the floor). It's late and I need my beauty rest.

 

[Swerd]

I'm very jealous btw that you're on vacation and rest of us are not.

Hey, I didn't take any time off this summer, so I earned it. Lake Placid was perfect. The mountains were green when we firrst arrived and soon hit their autumn colors. Our hotel had several canoes that you could take out onto Mirror Lake, which was along side the town. We took them out them several times. There was a small stone church (St. Eustace I believe) with real bells that chimed every hour and played about 5 or 10 minutes of hymns everyday at 5 pm. One of those times we were out in the canoe, we sat and listened as the bells chimed out the music. That was intensely beautiful.

Another highlight was the Great Adirondack Pub & Brewery .

I did route the hole a little deeper but honestly, unless I can find some thin foam, I think the drivers may be sticking out slightly. That's okay though, if I were a perfectionist, I would have gone to Salk himself and order the ST's . The ribbon does have some nice foam already on there but the others do not.

Parts Express sells two sizes of closed-cell gasketing tape, 1/8" × 1/2" and 1/8" × 3/8", and also sealing caulk which might be thinner. Probably the last thing you want to do is order more stuff from them . You may find some suitable weather stripping in a local hardware store. It is important to install the drivers with some kind of air seal behind them. I would avoid using silicone caulk as that seals too well, making it hard to ever remove the woofers.

If you do not want to use a glue mixture, you can give it a coat of primer and sand afterwards with 200-400 grit sandpaper. A second coat of primer should then seal the deal.

There are lots of effective ways to prime the edges. As long as you do one it should be fine.

Thanks for all the photos. They're looking good ! Nice job chamfering the inside of the speaker holes in the baffle.

 

[sawzalot]

I wonder if these could be built up at the base say an extra 3 inches to allow a bottom port instead of a rear port that way they could be placed closer to the wall in an HT application, I like the look of the taller yet narrow front really makes for a clean appearance across the front of the setup. I am chomping at the bit wanting to build speakers but I am still in the midst of a re-build of sorts that I started way too long ago they should get finished first then I will sweep up the shop and start again from scratch on something like these, excellent craftsmanship Skyline you have done a great job in a short time, I applaud your effort, sawz.

 

[skyline_123]

Hey, I didn't take any time off this summer, so I earned it. Lake Placid was perfect. The mountains were green when we firrst arrived and soon hit their autumn colors. Our hotel had several canoes that you could take out onto Mirror Lake, which was along side the town. We took them out them several times. There was a small stone church (St. Eustace I believe) with real bells that chimed every hour and played about 5 or 10 minutes of hymns everyday at 5 pm. One of those times we were out in the canoe, we sat and listened as the bells chimed out the music. That was intensely beautiful.

Another highlight was the Great Adirondack Pub & Brewery .

You certainly earned it but we don't deserve to hear about it . I can't believe you're rubbing it in like that (as I sit in my cubical, wide eyed, jaw dropped and pulling my hair trying to imagine the peacefulness).

I wonder if these could be built up at the base say an extra 3 inches to allow a bottom port instead of a rear port that way they could be placed closer to the wall in an HT application, I like the look of the taller yet narrow front really makes for a clean appearance across the front of the setup. I am chomping at the bit wanting to build speakers but I am still in the midst of a re-build of sorts that I started way too long ago they should get finished first then I will sweep up the shop and start again from scratch on something like these, excellent craftsmanship Skyline you have done a great job in a short time, I applaud your effort, sawz.

I'm not sure if this would be possible, being a transmission line design and all. I'm just speculatin' though.

And a word of advice: You said you're on the fence about building a set of speakers or finishing your other project. The hell with your other project, do yourself a favor and build these! I have been so in love with these things, I haven't even turned on a sub since I got them running. Hell, I probably have about 40% more work to be done on these before they're "complete". I haven't routed the edges of the baffle, I haven't stuffed the enclosure with any material and I haven't even begun to think about how I'm going to finish these. If I can manage the pain and suffering, I am going to tear these things down this weekend and starting the finishing work, hopefully by this weekend (if I can get my car working again).

Thank you guys for your kind words. If it weren't for people like yourselves, websites like this wouldn't be nearly as great!

Sean

 

[Swerd]

I wonder if these could be built up at the base say an extra 3 inches to allow a bottom port instead of a rear port that way they could be placed closer to the wall in an HT application…

You can mount the port on the front or back without any problem, but its opening should be centered 3" above the floor of the cabinet with the tube parallel to the floor. If you change the distance between the top woofer and the port, you change the bass tuning of the cabinet. What you propose may or may not change it by much, I can't be sure, but I'd leave the port exactly where it was intended.

This cabinet design, with the rear port, has been tested as close as 2-3" away from the wall behind, and the bass doesn't sound significantly different than if 2 feet away from the wall. In fact some people who listened said they like the sound closer to the wall, saying it made the bass sound a bit tighter. These TL speakers behave differently than standard bass reflex designs, and one of its advantages is that it allows greater flexibility in where you can place them.

Also, the original design was intended to be mounted on a roughly 2" high platform or plinth (board and spikes) that puts the tweeter at ear level. If you make it taller, that would change things. Again, it may be a small difference, but if it ain't broke, don't fix it .

PM me an email address and I'll send you a copy of what skyline posted.

 

[Swerd]

…The hell with your other project, do yourself a favor and build these! I have been so in love with these things, I haven't even turned on a sub since I got them running. Hell, I probably have about 40% more work to be done on these before they're "complete". I haven't routed the edges of the baffle, I haven't stuffed the enclosure with any material and I haven't even begun to think about how I'm going to finish these. If I can manage the pain and suffering, I am going to tear these things down this weekend and starting the finishing work, hopefully by this weekend (if I can get my car working again).

Sean - so I take it that you think these sound OK.

Once you finish them, be more careful about drooling, and always wash your hands before you fondle them .

 

[Swerd]

I wonder if these could be built up at the base say an extra 3 inches to allow a bottom port instead of a rear port that way they could be placed closer to the wall in an HT application...

sawz - I asked Paul Kittinger about your idea, and he answered:

"The port I modeled for this was 3" in diameter and 2.75" long, with its center, as Richard noted, 3" above the internal bottom of the cabinet's internal height of 43" and, with, the port mounted either on the baffle or rear panel parallel to the floor. If the port is, instead, set into the bottom of the cabinet and down-firing, its entrance will now be 2" above the internal bottom of the cabinet instead of 3". This will make a slight difference only in the response I modeled in the 500-1000 Hz region, affecting to a small degree or, perhaps, not at all the smoothness of the response. I really wouldn't know without re-modeling, but my intuition says the difference will be inaudible if even measurable.

That said, even with the base of the cabinet elevated to allow adequate breathing room for a down-firing port, I've never been a fan of this, at least not on normal vented cabinets so configured. I can clearly remember how very boomy the bass was at Iowa for one of Jim Holtz's big Statements with its down-firing port. Whether this ER18 ML-TL would be similarly affected, I can't say."

There, I hope that makes everything perfectly clear . I wish there was a simple direct answer to your question. I honestly believe that the bass is so good in Paul's design that there is no reason to change it.

 

[jinjuku]

. I can clearly remember how very boomy the bass was at Iowa for one of Jim Holtz's big Statements with its down-firing port. Whether this ER18 ML-TL would be similarly affected, I can't say."

There, I hope that makes everything perfectly clear . I wish there was a simple direct answer to your question. I honestly believe that the bass is so good in Paul's design that there is no reason to change it.

I will be rear porting my statements so hopefully no boundry effect to deal with. I would love to arrange a comparison of these two designs due to their proximity in price but wild difference in design approaches.

 

[darien87]

I will be rear porting my statements so hopefully no boundry effect to deal with. I would love to arrange a comparison of these two designs due to their proximity in price but wild difference in design approaches.

I wanted to make the mini statements a little while ago, but finances and my complete lack of knowledge about building crossovers got int the way.

I'll be interested to hear what you think of the statements when you get around to building them.

 

[skyline_123]

I will be rear porting my statements so hopefully no boundry effect to deal with. I would love to arrange a comparison of these two designs due to their proximity in price but wild difference in design approaches.

I was very interested in hearing/building the Statements. They are just a bit too large and it is quite an investment.

Some of the guys here in Oklahoma are trying to coordinate a DIY Audio GTG sometime in the January-March time frame, are you close? It would be really nice to be able to finally hear these things and compare them to the ER18's.

 

[jinjuku]

I was very interested in hearing/building the Statements. They are just a bit too large and it is quite an investment.

Some of the guys here in Oklahoma are trying to coordinate a DIY Audio GTG sometime in the January-March time frame, are you close? It would be really nice to be able to finally hear these things and compare them to the ER18's.

Sorry, but I'm in Louisville KY. It would be fun though. The only other member that I believe is even there me is Phil (Speakerman39)

 

[skyline_123]

Sorry, but I'm in Louisville KY. It would be fun though. The only other member that I believe is even there me is Phil (Speakerman39)

It's not THAT far of a drive, c'mon man.

This was very hard for me but I finally got a spare minute to disassemble my speakers to start the finishing process. I made a big mistake when I was building these. I got a little ahead of myself and glued the front baffle on before I got a chance to trim it and put a nice round over on it. I did trim the baffles but was only able to put a 1/4" round over on them, not ideal but will do.

In this shot, you can see I used the flush trim router bit to trim the overhang.

Here you can see I've put a 1/4" round over on the front baffle. I could have used a larger round over bit everywhere except the bottom edge (would have looked strange though). The larger round over bit is too tall and comes in contact with the MDF.

In this shot, I have filled all the screw holes and now they're ready for primer. They say that whatever treatment the outside of the enclosure gets, the inside should get as well, otherwise there will be two different expansion rates. I'm going to say no thanks to that.

 

[Alex2507]

I wanted a speaker that would “future proof” myself so that, if one day I develop a more sophisticated ear for great sounding speakers, I would still be 100% satisfied with my system.

So you think your itch is scratched, huh?
That's what Audioholics is all about ... being content with the gear you have.

I'm glad to see that you have an excellent set of speakers for your efforts.
You have fallen in with a fine group of fellows but don't think for a second that you're all done.
This is the beginning.

 

[GranteedEV]

Once you're done, I'd be interested in seeing a compression test on these things.