New DIY MTM Towers designed by Dennis Murphy and Paul Kittinger

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seamusmcfadden

Audiophyte
This circuit lowered the power to the Tweeters ten fold and maintained a flat response+_1.5dB. Could somebody here verify my nightmare and help me build a solution?
 

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roadrune

Audioholic
Something else must be wrong, i have built two pairs using the Founteks, and both have been abused for more then a year now without any issues.
One pair was measured to nearly 110db continiously playing "Long after youre gone" by Chris Jones btw...
 
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seamusmcfadden

Audiophyte
roadrune can you confirm this is the crossover circuit you deployed in both pairs of your MTM's with Fountek NeoCD3's? Or can you post a pic or link to something different?
 

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Swerd

Swerd

Audioholic Warlord
Has anybody built this MTM with NeoCD3 tweeters following the suggested crossover and blown the poop out of their Fountek tweeters?

Following the original document thread I built this MTM and everything was fantastic but the Fountek's lasted a week.
The schematic you showed is not the crossover for the ER18 MTM. Where did you get that? With a single cap of 3.3 µF for the tweeter, I'm surprised it lasted as long as it did!

The crossover schematic shown below is correct if you're using the Fountek ribbon tweeter. Roadrune's photos were a correct layout he made based on this schematic.

ER 18 MTM Ribbon Schematic.png
 
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seamusmcfadden

Audiophyte
...then why is the NeoCD3 over driven including passive components? Short life span for certain...no? Help me out here. This simulation uses the exact .frd and .zma files for each driver. It seems to me, high level playback will destroy this crossover and tweeter in no time at all.
 

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Swerd

Swerd

Audioholic Warlord
This should be the equivalent crossover to the authors of this MTM speaker design? Yes?
Which crossover did you use?

The crossover in post #641 is wrong. The correct one is in #644, #649, and #650?

If you used the correct crossover, it should work well… unless Fountek has recently changed that tweeter.
 
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Ken Hicks

Ken Hicks

Enthusiast
Why can't I see the images on the first pages of this thread? Sorry for being a noob.
 
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MrBoat

Audioholic Samurai
Why can't I see the images on the first pages of this thread? Sorry for being a noob.
Because photobucket hosting service is now a pay site and all images previously shared through them are now void unless the poster pays their price.
 
KenM10759

KenM10759

Audioholic Samurai
I'm very interested in making a pair (maybe two) of these together with my son sometime in 2018. Would anyone be willing to answer a few questions?

Cabinets: We have table saws, a jointer, smaller router, glue and plenty of clamps. What else might we need? I perhaps might be able to make that "outer front baffle plate" out of aluminum, as I have a CNC milling machine in my machine shop. While I know I can make it look VERY cool because I can radius the edges and anodize it any color, would there be any sonic good and bad about doing it?

Finishes: I can get a 4'x8' sheet of 3/4" MDF with cherry veneer for $76. Would this be easier than attempting veneer for the first time? If we attempt veneer, what thickness would be advised if we were to try wrapping around 1/2" radiused corners of the front baffle? If I use the cherry veneer MDF, we'd have to stick with square corners.

Any got photos of finished speakers they can post? I know Photobucket has turned to a giant moneysucker and they aren't getting my money either. I downloaded the documents kindly posted here, but didn't see and photos of finished product. How do the response plots of thee compare to something like the Salk Veracity HT-2L?

Thanks!!
 
Swerd

Swerd

Audioholic Warlord
Cabinets: We have table saws, a jointer, smaller router, glue and plenty of clamps. What else might we need? I perhaps might be able to make that "outer front baffle plate" out of aluminum, as I have a CNC milling machine in my machine shop. While I know I can make it look VERY cool because I can radius the edges and anodize it any color, would there be any sonic good and bad about doing it?
Your tools would be plenty to do the job.

An aluminum front baffle plate would look very cool, but there would be no sonic differences between it and MDF. For a while Jim Salk had anodized aluminum front baffle plates for the early versions of the SongTower RT (the ribbon tweet version). They sold out a long time ago and he uses MDF now. He says there was no difference in their sound.
Finishes: I can get a 4'x8' sheet of 3/4" MDF with cherry veneer for $76. Would this be easier than attempting veneer for the first time? If we attempt veneer, what thickness would be advised if we were to try wrapping around 1/2" radiused corners of the front baffle? If I use the cherry veneer MDF, we'd have to stick with square corners.
MDF with cherry veneer at that price sounds too good to pass up. If you like the look of that veneered MDF, I would go for it.

The first time I applied veneer (to much smaller cabinets) I found it difficult, and didn't like my results. It took me some practice before I got comfortable doing it. I've tried the contact cement method and the wood glue method. I much prefer the wood glue method. (Dilute wood glue with 1 part water & 1 part wood glue. Paint the MDF surfaces with 2 coats of wood glue, allowing each coat to dry. Apply the veneer, and use an electric iron to heat and melt the glue. Use a protective cloth between the iron and the veneer, and keep that iron moving all the time. Practice this on scrap wood before doing the real thing!!)

Some people apply veneer last after the cabinet is assembled, and others veneer the panels (while slightly oversized) before trimming and assembly. Think about it some, and take your pick. If I were doing it, I would veneer the MDF panels before assembly. Jim Salk says he has a "cold press". It's a large heavy plastic vacuum bag and an expensive vacuum pump. I've never seen one in use.

I've never tried wrapping veneer over rounded edges. I'm not sure a ½" round over would work without cracking the veneer. In the Salk speakers like the SongTower or the HT-2TL, all the veneered edges are on squared corners. The black painted MDF panel, that outer front panel, has the rounded over edges.
Any got photos of finished speakers they can post? I know Photobucket has turned to a giant moneysucker and they aren't getting my money either. I downloaded the documents kindly posted here, but didn't see and photos of finished product. How do the response plots of thee compare to something like the Salk Veracity HT-2L?
For photos see this link https://forums.audioholics.com/forums/threads/looking-for-proven-diy-that-is-better-than-klipsch-r-28f.110015/#post-1226125. You can look at photos of the Salk HT-2TL and copy it's look as much as you care to. The cabinets are the same dimensions.

The ER18 MTM's response compares closely to the HT-2TL. The crossover designer was the same person. The major sound quality difference is the Seas ER18 mid woofers produce a somewhat less detailed sound than the much more expensive Seas W18 magnesium alloy woofers of the HT-2TL.
 
KenM10759

KenM10759

Audioholic Samurai
Thank you Swerd for the detailed reply!!

I'm going to pick up 2 of the 4x8 sheets of 3/4" MDF with the cherry veneer. The lumber yard selling it told me they bought it two years ago for a local cabinet maker who went out of business before they paid for it, so they're sitting on FIFTY of them. One is all I need, but you know the Chapter 7 of Murphy's Law: If you have extra you won't need it, if you have no extra, you'll run out before the job is done.

This will be a six to nine months long project for us. It'll take some time to save up for everything needed and we want to be careful. I wonder now how much more it costs to use the Seas W18 woofers, and would they be useable without modifying the crossover.
 
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roadrune

Audioholic
If you look back some pages you will find pictures of my build.

If i recall correctly you will need one and a half sheet for this build, but one venered should be enough as the rest is hidden.

As long as you have access to CNC i would go for the veneered and mitre all joints. It is possible to do by hand, but it take some skill as every minor defect will show.
 
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