New DIY MTM Towers designed by Dennis Murphy and Paul Kittinger

[doors666]

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 (url omitted) would probably be OK for the bass circuit.
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 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.

Thanks, I like your reply, saves me money. I will try out the sledgehammers.

Erse has npe caps that are 3% DF and 5% tolerance. maybe those will be ok. Any opinions on polyester/mylar caps. These are usually 5% tolerance and poly like df. not exactly cheap, but still cheaper than poly.

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.

Ah well, then the 16awg is just 0.407ohms, within 10% of the original value and quite a lot cheaper. Infact its not much more than a iron core.

 

[doors666]

finally made the purchase. got the sledgehammer 15awg for the 1.5mh value, rest are 19awg aircore from madisound. for 10 and 25 uf, I got the madisound 10uf poly buyout for 60 cents each. for the woofer 22 uf I got the solen 400v as it looked like thats the cap that was driving both the woofers and didnt want to get 100v buyout from madi for this and so for higher voltage rating, got the solen. resistors are the wirewound ones from madisound, 15w for 1 ohm (no 0.5 ohms, so need to parallel) and 25w for 20ohms.

 

[David LR]

ER18 MTM Kits are on Meniscus

Just in case any one is interested, as I have been for a long time, Mensicus Audio is now stocking kits for the ER18. Sort of happened upon this randomly, I called Meniscus to discuss another speaker, mentioned the ER18 in passing, was informed they were just about to put it online as a kit ! My timing is usually not that great.

I think I'm going to bite, been "deciding" & "researching" long enough.

DIY Speaker Components | Replacement Speakers | and Speaker kits from Meniscus Audio Group

Hopefully, I'm not stepping on any toes here, as far as I know, Audioholics is not in the business of selling speaker parts, if so, I apologize. It's nice to see this design getting some more play. Anybody else considering this build ?

Dave

 

[Swerd]

Dave

Thanks for posting the link. Dennis had mentioned that ER18 MTM kits with Meniscus were in the works, but I didn't know when it would happen. I don't know if they will also sell cabinets for them. I guess that may depend on how many kits they sell.

Richard

 

[DirkL]

Hi Skyline_123,

just fell over the TL speakers designed by Kittinger and Murphy. Do you know where and how to get hold more info, such as detailed cabinet drawings, X-over design and components? I googled a while, but could not find anything.
Thanks a lot.
DirkL

 

[Swerd]

Hi Skyline_123,

just fell over the TL speakers designed by Kittinger and Murphy. Do you know where and how to get hold more info, such as detailed cabinet drawings, X-over design and components? I googled a while, but could not find anything.

I can send you a pdf file with all the details by email. Check your private messages for my email address.

You can also get the parts for either dome or ribbon tweeter versions as kits from Meniscus Audio.

 

[skyline_123]

Hi Skyline_123,

just fell over the TL speakers designed by Kittinger and Murphy. Do you know where and how to get hold more info, such as detailed cabinet drawings, X-over design and components? I googled a while, but could not find anything.
Thanks a lot.
DirkL

Hi DirkL, welcome to the forums! You had me worried for a second because most of the information on building these is on the first page. I thought for a second that the links for all the pictures were dead but I looked and they're still there.

 

[DirkL]

Hi Skyline123,

Thanks for the welcome.
It seems I am the only Idiot in the world, who still has to browse with IE8 and I could not view all the embedded pictures.
Swerd has already sent me pdf file with all info and I am currently checking availability of material here in Australia. Shipping costs from US kill you (charge you $180 for a kit)!
I will report on the outcome!
THX

 

[DirkL]

• Mount the tweeter’s center ¾" away from the vertical center on the front baffle. Mirror image the off-set tweeters in a pair of speakers.

Hi Skyline123,
Can you or anyone else tell me why in this kit the tweeters are located just out of center line? We are talking just ¾" or 19mm horizontally, which should not be a massive gain in compacting the other drivers.
Did anyone ever try to build this kit in-line? I don't want to sound like a heretic, just curious. I have been building all sorts of speakers in the last 25 years, but this driver layout looks odd to me.
Thanks for your info

 

[Swerd]

Can you or anyone else tell me why in this kit the tweeters are located just out of center line? We are talking just ¾" or 19mm horizontally, which should not be a massive gain in compacting the other drivers.

Did anyone ever try to build this kit in-line? I don't want to sound like a heretic, just curious. I have been building all sorts of speakers in the last 25 years, but this driver layout looks odd to me.

Dirk

High frequency sound coming from tweeters will interact with cabinet edges, causing small peaks and valleys in the frequency range of about 4 to 8 kHz. The exact frequency is determined by the distance from the tweeter to the cabinet edge.

If the tweeter is centered in a tall narrow cabinet such as this one, there will be two tweeter-to-edge distances that are the same, creating the possibility of larger peaks and valleys. If the tweeter is slightly off center there will be two slightly different tweeter-to-edge distances. They may generate more peaks and valleys, but they will be smaller in amplitude.

The crossover was designed with the off center tweeter, but if the tweeter is centered, I don't believe it will make a significant difference.

This is generally similar to rounded over the cabinet edges on a speaker. It's a nice touch, but makes a small difference in the measurable sound. Note that I say it can be measured, but it is not known just how audible a difference it makes.

 

[DirkL]

Swerd,

One may get as old as Methuselah and still learn something new.
Thanks for the explanation, absolutely makes sense. But as you said, it is always a bit of a gamble, what of the measured values can actually be heard. Better step on the safe side!
Thanks again!

 

[mattsk8]

Just in case any one is interested, as I have been for a long time, Mensicus Audio is now stocking kits for the ER18. Sort of happened upon this randomly, I called Meniscus to discuss another speaker, mentioned the ER18 in passing, was informed they were just about to put it online as a kit ! My timing is usually not that great.

I think I'm going to bite, been "deciding" & "researching" long enough.

DIY Speaker Components | Replacement Speakers | and Speaker kits from Meniscus Audio Group

Hopefully, I'm not stepping on any toes here, as far as I know, Audioholics is not in the business of selling speaker parts, if so, I apologize. It's nice to see this design getting some more play. Anybody else considering this build ?

Dave

I've got all the components, just waiting for a bit of time. Have to finish a staircase side job and a kitchen reface side job. Hope to start these in a month or so. Can't wait to here how they sound! Meniscus Audio is about 1/2 hour drive from me so I may cheat and go there and see what he has to say about any tricks or tips before the build!!

 

[GranteedEV]

I've got all the components, just waiting for a bit of time. Have to finish a staircase side job and a kitchen reface side job. Hope to start these in a month or so. Can't wait to here how they sound! Meniscus Audio is about 1/2 hour drive from me so I may cheat and go there and see what he has to say about any tricks or tips before the build!!

While you're there, see if they've got Jeff Bagby's new Mandolin and Piccolo kits up for a possible listen and give us your impressions

 

[mattsk8]

While you're there, see if they've got Jeff Bagby's new Mandolin and Piccolo kits up for a possible listen and give us your impressions

Will do!! I'm also going to forge ahead w/ your recommendation for the Zaph 5.3c. Had to do a bit of research on the other forum just so I could feel like I kinda made the decision but it just proved you were right again

 

[GranteedEV]

Will do!! I'm also going to forge ahead w/ your recommendation for the Zaph 5.3c. Had to do a bit of research on the other forum just so I could feel like I kinda made the decision but it just proved you were right again

Your situation with the giant TV cabinet definitely means there's really no "right". I just hope it works out for you. Those ZA14s are nice budget drivers and I suspect you'll like the vifa metal tweeter too... much a matter of getting good interaction with the environment.

 

[David LR]

I've got all the components, just waiting for a bit of time. Have to finish a staircase side job and a kitchen reface side job. Hope to start these in a month or so. Can't wait to here how they sound! Meniscus Audio is about 1/2 hour drive from me so I may cheat and go there and see what he has to say about any tricks or tips before the build!!

Looks like you're a re-modeling contractor or a GC of some kind, you'll probably have those speaker cabs done in a week !! I'm ordering my stuff this week.
Good luck with your project, looking forward to your comments.

Dave

 

[mattsk8]

While you're there, see if they've got Jeff Bagby's new Mandolin and Piccolo kits up for a possible listen and give us your impressions

Got over to Meniscus today but unfortunately it wasn't until 4:45 (stupid work ) and he closes shop at 5. Didn't get much of a chance to look around but he did show me some 3 ways he's currently building and said he'd call when they were done. Xovers are insane! Can't wait to here em. He's also got me torn between the Swopes and the Zaphs now. I think it'll just come down to price. What do you think Grant? Have you heard the Swopes? He also didn't see a pic of my situation, just told him and he's heard the Swopes and thinks they might be a good candidate for my situation, hasn't heard the Zaphs.

Looks like you're a re-modeling contractor or a GC of some kind, you'll probably have those speaker cabs done in a week !! I'm ordering my stuff this week.
Good luck with your project, looking forward to your comments.

Dave

I wish it would only take a week! 4 kids makes it tough to find the spare time. Hope to get the ball rolling in about a month. I used to build custom cabinets and trim and some remodels, hardwood flooring, etc, but the economy turned me to plastic recycling . I manage a recycling plant now but miss doing the building for sure. At least the bills are getting paid!

That's awesome that you're ordering up! Guess we'll be building together! I'm fairly certain you won't be let down. The guys here have yet to steer me wrong. I just finished a pair of Statements for my dad and can't wait to hear how these ER18s will sound next to those.

 

[mattsk8]

While you're there, see if they've got Jeff Bagby's new Mandolin and Piccolo kits up for a possible listen and give us your impressions

Got a chance to go over to Meniscus again yesterday, they called because the speakers I was talking about a couple posts ago were finished and I told him I wanted to listen when they were done w/ em. Holy smokes do they ever sound good!!! He said they were around $12k! He also said he had around $3k just into xover components ! He built them w/ adjustable xovers because the guy he made them for is using a tube amp to drive them so he wanted him to be able to adjust the mids and highs. I'd give my listening impressions and what not but I don't think these will be available as a kit, was a custom build/request from a customer. Just thought I'd post pics cuz I thought they were pretty phenominal sounding speakers!

As far as the Mandolin and Piccolo kits go, he didn't have any assembled yet that I could listen to . I'll keep checking back though.

Sorry about the grainy Droid pics, was kinda dark in there

 

[tecexec]

This is NOT a TQWT. It seems to be a simple ported system is a tower configuration, some would call it a "Helmholtz Resonator". Generally, Helmholtz Resonators have the same width and depth to approach a column (tube like in a pipe organ). Additionally if the tuning is 31 HZ, the line would have to be 109 1/4 inches long. Again, this is NOT a transmission line!

 

[GranteedEV]

This is NOT a TQWT.

Right, it's an ML-TL.

It seems to be a simple ported system is a tower configuration, some would call it a "Helmholtz Resonator". Generally, Helmholtz Resonators have the same width and depth to approach a column (tube like in a pipe organ)

Erm, no. Generally, speakers using Helmholtz resonances have very even internal pressure loading the resonator. IE, a cube, or a sphere. As soon as one dimension becomes longer than the other two, the internal pressure relationships change. An ML-TL has less reflex loading, and instead uses the mass to "extend" the line. It's more similar than not to a reflex speaker, but you can't label this a reflex speaker, and most of the time you can't label reflex speakers as true reflex speakers either!!

Additionally if the tuning is 31 HZ, the line would have to be 109 1/4 inches long.

Right. It's not a true transmission line in the traditional sense. Likewise, most tower speakers claiming to be vented are not truly helmholtz resonators!! In essense, you can treat this as whatever you like, the key is that it's behavior was modelled more accurately than just "Internal Box Volume vs Vent tuning" - the vent's placement, the driver's placement, the box's dimensions, all with respect to internal standing waves, were factored in!

Again, this is NOT a transmission line!

Not a true transmission line, but neither are quarter wave resonators in general. A true transmission line's only goal would be to flatten out the impedance hump at driver resonance, and should have zero output from the terminus as a result. In essense, the only point of a "true TL" would be for someone committed to using a crappy voltage limited amp.

As soon as you start to get terminus output, you will have two impedance peaks, even if one is small and doesn't show up on some charts, it will still be there. Sometimes the chart doesn't go below 20hz so people just miss the lower peak, and sometimes the chart lacks resolution. But if there's output from the terminus contributing to total SPL, it doesn't make sense for it to not affect the driver's behaviour near tuning, although sometimes the contribution is very mild and nothing like a typical "knee" for vented speakers.

Overall, if you're using any kind of resonator to augment bass response, it's best to understand what's going on, as the basic sims don't factor everything in. That's what makes ML-TL optimal - not the fact that it's a Transmission Line.