New DIY MTM Towers designed by Dennis Murphy and Paul Kittinger

[Swerd]

The only experience I've had with veneering, I followed Lou C's Veneer Tutorial. That uses the contact cement method, the kind with the stinky organic solvent – I did it outdoors. It worked in my hands the first time I tried it, and that says lots right there. I was working with a small sized bookshelf speaker cabinet for the CAOW1 speakers.

I've wondered if the wood glue and hot iron method would be easier or harder to do, but I've never tried it.

I've also wondered if veneering MDF sheets (cut to be slightly oversized) and using a platform press instead of a vacuum bag while the glue dries would be doable for a large tower speaker such as the ER18 MTM. After veneering, the sheets can be trimmed to final size and assembled into a cabinet. Like all woodworking, you learn a lot the first time you go through a procedure, including ways that shouldn't be done again .

And yes, finding some one else who does veneering and finishing professionally is not a bad idea. If you are thinking of a paint finish, I urge you to take the cabinets to an auto body shop and have them use automotive paints and their spray booth. Their results are superior to anything I could do with paint. People I know who did that were surprised how little it cost to finish their speakers that way.

 

[RPM]

Optional Woofer

I've been following this thread with great interest as I'm trying to narrow my choices for a DIY speaker build. At one point I was looking at the Troels Gravesen CNO-25 using the SEAS Nextel coated mids and a Cresendo tweeter. I wend as far as purchasing the four W18NX001 mids from Solen since they were on sale. Unfortunately, I'm beginning to have second thoughts and would like to build the ER18 MTM instead.

My question for the experts out there is could I still use the W18NX001 woofers in this MTM configuration using the Dayton tweeter and the x-over components listed at the beginning of this thread or am I better off to return the aforementioned woofers in exchange for the ER18RNX? After looking over the specs of both woofers the only big difference I see are the VAS #'s (24L for the W18NX001 vs. 32L for the RR18RNX).

Any input would be helpful,

Thanks,
r.

 

[TLS Guy]

I've been following this thread with great interest as I'm trying to narrow my choices for a DIY speaker build. At one point I was looking at the Troels Gravesen CNO-25 using the SEAS Nextel coated mids and a Cresendo tweeter. I wend as far as purchasing the four W18NX001 mids from Solen since they were on sale. Unfortunately, I'm beginning to have second thoughts and would like to build the ER18 MTM instead.

My question for the experts out there is could I still use the W18NX001 woofers in this MTM configuration using the Dayton tweeter and the x-over components listed at the beginning of this thread or am I better off to return the aforementioned woofers in exchange for the ER18RNX? After looking over the specs of both woofers the only big difference I see are the VAS #'s (24L for the W18NX001 vs. 32L for the RR18RNX).

Any input would be helpful,

Thanks,
r.

If you use different drivers, then the whole cabinet and crossover have to be redesigned from scratch.

 

[Swerd]

If you use different drivers, then the whole cabinet and crossover have to be redesigned from scratch.

I completely agree with TLS Guy.

Note that when Paul Kittinger designed the cabinet, he used Zaph's measured T/S parameters (Qts = 0.35, Vas = 26.3 L, Fs = 39.1 Hz), not those listed by SEAS.

It is possible that the W18NX woofer might (and I emphasize the word might, might not is just as likely) work OK in that cabinet. Those cabinet dimensions were very close to the dimensions of the Salk HT2-TL which uses the SEAS W18EX magnesium cone woofers. So the bass performance of the ER18 MTM cabinet with the Nextel woofers might be OK.

But Nextel and Reed/Paper coned woofers will very likely have different high frequency roll-off patterns requiring different crossovers to the tweeter. So my advice is the same as TLS Guy's, stick with original design.

 

[GranteedEV]

I've been following this thread with great interest as I'm trying to narrow my choices for a DIY speaker build. At one point I was looking at the Troels Gravesen CNO-25 using the SEAS Nextel coated mids and a Cresendo tweeter. I wend as far as purchasing the four W18NX001 mids from Solen since they were on sale. Unfortunately, I'm beginning to have second thoughts and would like to build the ER18 MTM instead.

As far as the box, the nextel cones can be dropped in pretty well. The difference in tuning would likely be around 1/2 a db and could be compensated for with a slightly longer vent (just guessing, but probably like 3/4 of an inch).

Based on an eyeball of the impedance and response curves:

They DO look <i>eerily</i> similar. Though it's tough to draw any conclusions based those tough-to-read graphs. The ER18s are stated to be about a db more sensitive than than the W18NX001s however so a drop in replacement is out of the question either way. The ER18's impedance also does rise a bit faster above 2khz (it does have two less shorting rings and no phase plug, after all). Not sure if i'd call it meaningfully faster as far as transfer functions are concerned, but it's definitely a difference.

Your best bet, would be to send two of the W18NX001s down to Dennis for measuring. For all I know it might just take an extra resistor here or there. Either way, since it's a drop-in replacement in the ER18's test box, i'm sure dennis could work something out for you with the fountek tweeter. Not sure if he's got the dayton tweeter on hand.

Here is his contact info:

http://murphyblaster.com/content.php?f=main.html

 

[RPM]

Thanks for the quick responses. I will try to contact Dennis Murphy and go from there.

It's not the end of the world if I can't use the Nextel drivers....they just have a coolness factor about them and I thought they may work with this MTM configuration.

I'm brand-new to the speaker design thing so forgive me for my lack of knowledge. I'll keep everyone posted on the progress.

 

[RPM]

Internal Braces

Another question about the internal construction...do the two braces behind the woofers make contact with the back of the woofer or should there be a gap? I have read about the "Fat" Thor TL speaker design using an internal brace that makes contact with the woofers to couple everything together.

Any pros/cons with this theory?

 

[Swerd]

Another question about the internal construction...do the two braces behind the woofers make contact with the back of the woofer or should there be a gap? I have read about the "Fat" Thor TL speaker design using an internal brace that makes contact with the woofers to couple everything together.

Any pros/cons with this theory?

My first reaction is to avoid contact between a brace and the woofer magnet or frame. This is to avoid transmitting vibrations to the cabinet… Of course the woofer frames are already directly attached to the front baffle.

Still, I am unacquainted with this coupling idea so I can't comment further.

 

[GranteedEV]

My first reaction is to avoid contact between a brace and the woofer magnet or frame. This is to avoid transmitting vibrations to the cabinet… Of course the woofer frames are already directly attached to the front baffle.

Still, I am unacquainted with this coupling idea so I can't comment further.

Right. You don't want the driver coupled to any part of the box.

In fact this is why having a thick, rigid, and damped baffle is important. Because the drivers couple to the baffle, that's where most mechanical energy is reradiated from.

 

[capricious]

Sorry if i've missed this in one of the many posts earlier ... but is there a plan for a center channel?

 

[doors666]

Sorry if i've missed this in one of the many posts earlier ... but is there a plan for a center channel?

If not, what would be a suitable center channel. What is a good approach for center channels. In commercial world, its rather simple, get it from the same manufacturer, if possible, same series. In DIY world, it gets a little bit more complicated. Is it better to go with the same designer's center channel using any drivers, or is it better to go with a center channel using the same drivers by any designer?

For some time, I will use a phantom, but then would like a center in the long run, just to be able to adjust the center channel volume for some movies where it doesnt sound correct. How good a job does a regular MT do for center channel? I guess the off axis performance is also very important.

 

[TLS Guy]

If not, what would be a suitable center channel. What is a good approach for center channels. In commercial world, its rather simple, get it from the same manufacturer, if possible, same series. In DIY world, it gets a little bit more complicated. Is it better to go with the same designer's center channel using any drivers, or is it better to go with a center channel using the same drivers by any designer?

For some time, I will use a phantom, but then would like a center in the long run, just to be able to adjust the center channel volume for some movies where it doesnt sound correct. How good a job does a regular MT do for center channel? I guess the off axis performance is also very important.

It is difficult to say, but in general I would say same designer trumps same drivers.

My researches have shown that a good center channel needs to differ from the mains in some important respects to do its job and blend well.

 

[wyowolf]

What center channel would be good for this?? I am going to be building these soon and would like to replace my worthless center channel but would like it to match these w a Center and a sub.

any links to a matching center would be appreciated

Frank

 

[GranteedEV]

What center channel would be good for this?? I am going to be building these soon and would like to replace my worthless center channel but would like it to match these w a Center and a sub.

any links to a matching center would be appreciated

Frank

I believe Dennis' Philharmonic center uses a very similar driver complement (Seas ER15 + Fountek Neo CD3) so maybe he's got a crossover for it ready. Drop him an email or PM.

 

[capricious]

I just placed an order for the ribbon version at meniscus audio. I have the arucoply cut and ready. I just need to trim some of the braces, and i'll be all ready to start glue things up
This build is going to be interesting. Hope this is my last build for quite sometime.

 

[jay53]

ER18 Plans

Richard,

I am not yet qualified to send you a PM hence this request.

I am contemplating Left, Right and center speakers for HT and ER18 seem a good option. Would it be possible to get a copy of the plans ?

Thanks

Jay

 

[skyline_123]

I just placed an order for the ribbon version at meniscus audio. I have the arucoply cut and ready. I just need to trim some of the braces, and i'll be all ready to start glue things up
This build is going to be interesting. Hope this is my last build for quite sometime.

I've never heard of arucoply. What is it? What are the benefits of using it? Good luck with the build. Be sure to keep everyone posted on progress. Like you, I hoped that this would be my last build too. For mains, I think they are. My craving to build other speakers hasn't gone away but I now get to build for friends and family (although I will be building some subs in my near future ).

(shhh, don't tell the wife but there's one more of these bad boys coming)

Richard,

I am not yet qualified to send you a PM hence this request.

I am contemplating Left, Right and center speakers for HT and ER18 seem a good option. Would it be possible to get a copy of the plans ?

Thanks

Jay

Welcome to the forums. You're off to a great start if you've already chosen to build these.

You can get your posts up by posting here so you can send PM's. Otherwise the full set of plans is on the first page of this thread.

 

[doors666]

There's a center channel by Dennis murphy in this thread HTGuide Forum - Dayton RS WMTW Center & TMWW Mains. I havent gone through the whole thread as its quite long. Anyone tried this. Any other dennis's center channels in public domain?

 

[Swerd]

Richard,

I am not yet qualified to send you a PM hence this request.

I am contemplating Left, Right and center speakers for HT and ER18 seem a good option. Would it be possible to get a copy of the plans ?

Jay

I sent you a PM with my email address. I can't send an attachment by PM, but if you email me back, I'll send you the pdf version of the plans.

Richard

 

[capricious]

I've never heard of arucoply. What is it? What are the benefits of using it? Good luck with the build. Be sure to keep everyone posted on progress. Like you, I hoped that this would be my last build too. For mains, I think they are. My craving to build other speakers hasn't gone away but I now get to build for friends and family (although I will be building some subs in my near future ).

(shhh, don't tell the wife but there's one more of these bad boys coming)

Arucoply is a the ply you get at home depot without any veneer facing like the birch ply or oak ply. It is mostly void free, has about 8 layers, and is actually cheaper than MDF. I find it easier to work with as i hate having to deal with MDF dust. Also one face of the ply is sanded smooth, and the other is a little rough. So for my purpose, this is perfect.

I sent you an email about the center channel you mentioned earlier. Can you please email the plans? I'd love to have a matched LCR ....

PS: That woofer looks great ... what is it? Specs?