New DIY MTM Towers designed by Dennis Murphy and Paul Kittinger

[Alex2507]

Stick on foam weatherstripping works. PE also sells some that is made with closed cell foam.

Here's the PE offering:

http://www.parts-express.com/wizard...AT&srchCat=818&CFID=33304391&CFTOKEN=19434894

I used the 3/8" tape on my subs and the Speaker Sealing Caulk on my BR-1's. The caulk is a rather permanent type seal because it is so adhesive. After using it once I opted for the speaker gasket tape because it is application specific and if I ever had to remove the driver it wouldn't be with pry bars.

 

[David LR]

Jeff G. & Skyline -

Thank you both for your comprehensive & helpful answers. I will probably end up building these speakers, $600 or so is not a bad investment for what sounds like a very high quality set of speakers.

When I do, I'll post the build & review.


Thanks again, guys. Love the discussions.

David

 

[Swerd]

David

Send me PM with your email address if you want a pdf copy of the plans for these speakers. I can't remember if I already sent you one before.

If anyone else is interested, please send me a PM with an email address.

 

[GranteedEV]

I did some playing around today with REW and I seem to have a nice little peak at 200hz. This was identified with the RS SPL meter and it actually showed up with the built in mic on the computer. Really, I just used the computer to generate the signals but it was nice to have some confirmation.

Although there is a peak at 200hz, I seem to only be able to hear this disturbance on one song, the same song that brought it to my attention to begin with. The song is called "Breaking the Silence" by Janis Ian. At about the the 36 second mark, she sings "and left to lie alone". The word "alone" is giving me the trouble. Maybe someone can tell me if that's just the way it's recorded.

I doubt it's the speakers. More likely it's a room problem.

Swerd, I recently had a conversation with GranteedEV about why a sideways MTM is not the best idea. Maybe he can chime in and repeat what he told me. I could try and regurgitate what he told me but I'd end up messing things up.

I still don't think it's the best idea. The side wall reflections just won't sound balanced. If you do use a sideways 2-way MTM then at least stuff the side walls with absorption panels to tame the tweeter reflections.

 

[tom.terrific]

I had planned to begin this build last Spring, so I'm way behind schedule. The good news is, it looks like I'll be able to finally get started this November, and I can't wait.

Any body else complete their build, and stopped grinning long enough to write something about the sound/experience?

 

[JohnnyK]

I use Dennis' MBOW1-3way speakers for my main speakeras and a MBOW1 for my center speaker. The surrounds are NHT speakers. The MBOW1-3 way speakers produce a very large soundstage with great imaging. The are the best sounding speakers that I ever had. Dennis does a great job.

 

[skyline_123]

I use Dennis' MBOW1-3way speakers for my main speakeras and a MBOW1 for my center speaker. The surrounds are NHT speakers. The MBOW1-3 way speakers produce a very large soundstage with great imaging. The are the best sounding speakers that I ever had. Dennis does a great job.

One complaint I have about Dennis Murphy is that his website doesn't have more pictures. If you have any, lets see those MB0W1's you speak of. I've often contemplated building those or the MB27's or CA0W1's for surround sound duty.

 

[jinjuku]

One complaint I have about Dennis Murphy is that his website doesn't have more pictures. If you have any, lets see those MB0W1's you speak of. I've often contemplated building those or the MB27's or CA0W1's for surround sound duty.

Yep, they guy can design speakers. I wouldn't hire him for Web dev anytime soon

 

[wyowolf]

Hey guys, where would one get plans for these? I have tried to PM the author but I dont have enough post count to do that?

thanks in advance... beautiful work by the way...

Frank

 

[skyline_123]

Hey guys, where would one get plans for these? I have tried to PM the author but I dont have enough post count to do that?

thanks in advance... beautiful work by the way...

Frank

You can build them with the diagrams on the first page but if want a nice PDF, go to the Post Pad to get to your minimum post level so you can PM. The good folks here don't frown upon that sort of thing.

 

[wyowolf]

Post Pad??

thanks is that on the site? or somewhere else?

 

[wyowolf]

Got the plans, thank you very much!

 

[jazzman53]

Fantastic job, Richard!

BTW, I love your router table.

 

[doors666]

xo parts

I am planning to make these and i am in the process of getting the parts. I am on a budget and need to cut costs. I see that in the BOM published on the first page, all the caps are polys and the 1.5mh inductor is 15 awg aircore. Any disadvantage of using electrolytics for the caps. Is there any cap that shouldnt be npe.

what about using laminated core like 16awg or 18awg from erseaudio (sorry, I cant post links). 16awg has dcr of 0.16 and power handling of 400w. 18awg has 0.28 ohms and 300w. Any disadvantages of using laminated cores.
For aircores, I cant seem to find 15awg at madi or erse. any issues with using 14awg or 16 awg

I also would like a cheap amp. How good the 80w into 4 ohms emotiva A100 will be for these. How much power can these speakers handle fullrange and how much with a sub.

 

[TLS Guy]

I am planning to make these and i am in the process of getting the parts. I am on a budget and need to cut costs. I see that in the BOM published on the first page, all the caps are polys and the 1.5mh inductor is 15 awg aircore. Any disadvantage of using electrolytics for the caps. Is there any cap that shouldnt be npe.

what about using laminated core like 16awg or 18awg from erseaudio (sorry, I cant post links). 16awg has dcr of 0.16 and power handling of 400w. 18awg has 0.28 ohms and 300w. Any disadvantages of using laminated cores.
For aircores, I cant seem to find 15awg at madi or erse. any issues with using 14awg or 16 awg

I also would like a cheap amp. How good the 80w into 4 ohms emotiva A100 will be for these. How much power can these speakers handle fullrange and how much with a sub.

Air core inductors are a bad idea, and you need to keep the resistance low. 14 or 16 awg will be fine. Again electrolytics are a poor choice and change value over time. Solen Poly caps are a very good deal.

 

[doors666]

Air core inductors are a bad idea, and you need to keep the resistance low. 14 or 16 awg will be fine. Again electrolytics are a poor choice and change value over time. Solen Poly caps are a very good deal.

The original BOM uses all aircores, thats why I was thinking of using laminated cores, they are comparatively quite cheaper also. Even an 18awg laminated core betters 15awg aircore in dcr. NPEs do change value over time, but thats a long time 15-20 years we are talking about and in the price of a poly, I can get 10 npes. Apart from the drift in values, no other issues right? I can upgrade them later to polys when I have more money.

 

[TLS Guy]

The original BOM uses all aircores, thats why I was thinking of using laminated cores, they are comparatively quite cheaper also. Even an 18awg laminated core betters 15awg aircore in dcr. NPEs do change value over time, but thats a long time 15-20 years we are talking about and in the price of a poly, I can get 10 npes. Apart from the drift in values, no other issues right? I can upgrade them later to polys when I have more money.

You have hysteresis distortion with iron core and saturation issue. I have never had luck with electrolytics, and the forward resistance is too high. They are lousy in crossovers.

Go to Madisound, they have really good value side winder inductors and Solen polycaps at very reasonable prices. Building speakers is very hard and exacting work, that pays good dividends. Do not hobble your project before you cut your first board. Do it right the first time.

One of the reasons you are building this to avoid the cheap and very nasty crossovers in commercial speakers, right?

 

[lsiberian]

You have hysteresis distortion with iron core and saturation issue. I have never had luck with electrolytics, and the forward resistance is too high. They are lousy in crossovers.

Go to Madisound, they have really good value side winder inductors and Solen polycaps at very reasonable prices. Building speakers is very hard and exacting work, that pays good dividends. Do not hobble your project before you cut your first board. Do it right the first time.

One of the reasons you are building this to avoid the cheap and very nasty crossovers in commercial speakers, right?

Agreed. You are putting way too much work in this to go half way give your best and save up for it if you have to. I've been saving money and buying parts for 2 years. I have yet to get everything, but when I do finish the speakers they will be the precise thing I want them to be.

 

[Swerd]

I am planning to make these and i am in the process of getting the parts. I am on a budget and need to cut costs. I see that in the BOM published on the first page, all the caps are polys and the 1.5mh inductor is 15 awg aircore.

Because you mentioned the 1.5 mH inductor, I assume you're talking about the dome tweeter version of this design.

I included the 1.5 mH 15 g aircore inductor for a simple reason. That is what was used when a mock-up crossover was thrown together from existing parts and tested. I think substituting a steel-core inductor of 1.5 mH, such as a Madisound Sledgehammer would probably be OK for the bass circuit.

Any disadvantage of using electrolytics for the caps. Is there any cap that shouldnt be npe.

There are two disadvantages with NPE capacitors in crossover circuits. One reason (already mentioned by others) is that their capacitance drifts over time. True, that time frame is a long time. I don't know about you, but I'll be out of spec before NPE caps made today .

But the second (and main) reason I avoid using NPE caps is that their variance from their specified value when new is often greater than ±10%. So if you want two 10 µF caps, how many NPE caps do you need to buy and check before you find two of that value? I'd rather just buy two metalized polypropylene 10 µF caps and be done with it. All the MPP caps I've checked have had nearly the exact value as printed on them.

I also would like a cheap amp. How good the 80w into 4 ohms emotiva A100 will be for these. How much power can these speakers handle fullrange and how much with a sub.

I think 80 watts at 4 ohms will have no problem driving these speakers. Even 50 watts at 8 ohms, without a sub, sounded pretty good.

 

[GranteedEV]

For aircores, I cant seem to find 15awg at madi or erse. any issues with using 14awg or 16 awg

I don't think 14 awg would be a big deal. The parts list states 0.38ohm DCR for 15 awg, while the 14 awg air core sold by meniscus states 0.30ohm DCR... now i'm not an expert but I can't imagine 0.08 ohms making enough of a difference to be concerned.