New DIY MTM Towers designed by Dennis Murphy and Paul Kittinger

[Swerd]

Nothing you mention (carpeting, speaker positions, polyfill, etc.) stands out as an obvious source of the bass problem you described.

Dumb thought: Have you made sure that your receiver doesn't have the bass boosted, set by you (or someone else) some time ago and forgotten?

I can only say all this loosely resembles my own experience with SongTowers, which share the bass design of the so-called mass loaded transmission line (MLTL). In several recordings (such as with bass drum), I heard surprising amounts of bass that I hadn't heard before with different speakers. It was startling when I first heard it, but I didn't think it was a problem. In fact, I liked it. I have since learned this is what MLTL bass alignment is capable of doing. Certain recordings can excite just the frequencies where the TL port is most potent. I don't think you ever heard that with your previous speakers.

I'm not sure if this is the same thing as the "ringing" you described, but I'm afraid its the best I can do.

 

[erpe]

Hi. I have a small question. I can not get coils for crossover (fountek version) - 0,4mH 0,29ohm / I can only get 0,4mH 0,57ohm. Will there be a problem if I will order them and use them instead of the one that should be originally?

 

[jinjuku]

Where are you sourcing the inductor from?

 

[Swerd]

Hi. I have a small question. I can not get coils for crossover (fountek version) - 0,4mH 0,29ohm / I can only get 0,4mH 0,57ohm. Will there be a problem if I will order them and use them instead of the one that should be originally?

An inductor coil 0.4 mH at about 0.29 ohms is made with 18 gauge copper wire.

Here are several available in the USA:

Jantzen 0.40mH 18 AWG Air Core Inductor 255-224

0.40mH

and one with 19 g wire The Madisound Speaker Store

I'm not sure what gauge wire yields 0.59 ohms in a 0.4 mH inductor coil, but it will probably work without a problem. Generally, I try to use nothing smaller than 20 gauge.

 

[erpe]

I am in Europe and I can order rest from the store that is 0,72mm ( i think it is 21 gauge) 0,40mH 0,579 ohm 5% tolerance ( instead of 0,29 ohm that is in original crossover) for almost 1/10 price of Jantzen 0.40mH 18 AWG ( I had missed it from the list when I was ordering other parts / I discovered it yesterday when I open my package after 3 months that I got it ). Do You think it will be ok?

 

[Swerd]

I am in Europe and I can order rest from the store that is 0,72mm ( i think it is 21 gauge) 0,40mH 0,579 ohm 5% tolerance ( instead of 0,29 ohm that is in original crossover) for almost 1/10 price of Jantzen 0.40mH 18 AWG ( I had missed it from the list when I was ordering other parts / I discovered it yesterday when I open my package after 3 months that I got it ). Do You think it will be ok?

It will probably be OK.

Consider the total impedance of that shaping LCR circuit for the tweeter. The 0.4 mH inductor is in series with a 2 ohm resistor and a 22 µF capacitor. With an 18 g inductor the total DC resistance is 2.3. With a 0.579 ohm inductor the total becomes 2.6 ohms, and with a 0.72 ohm inductor it becomes 2.7 ohms. I don't think a change from 2.3 to 2.7 will make much difference for that circuit.

The inductor coil that I would avoid changing is the large one (1.25 mH 16 gauge) in the woofer circuit. 18 gauge wire might be OK, but not smaller than that.

 

[erpe]

It will probably be OK.

18 gauge wire might be OK, but not smaller than that.

But does 21 gauge (the one that I would like to order 0,4mH) for tweeter circuit will be ok ( are You talking about this one)?

Ps. Smaller AWG means higher value (19,20, etc)? Sorry I never use U.S. standards...

 

[Swerd]

But does 21 gauge (the one that I would like to order 0,4mH) for tweeter circuit will be ok ( are You talking about this one)?

Ps. Smaller AWG means higher value (19,20, etc)? Sorry I never use U.S. standards...

Yes, I mean the 0.4 mH inductor in the tweeter circuit.

And yes, in the US, the larger number AWG means smaller diameter wire. For example, 16 gauge is thicker than 18 gauge, and 18 gauge is thicker than 19 gauge, etc.

 

[Devil]

Hi guys!

My name is Oliver and I´m from Germany.

I´ve build the ER 18 MTM for a friend:

The pics was made in my party-room, so this is not the living room of my friend.

The veneer is called "SaRaiFo (save the rain forrest) Makasser" and is made of german wood. It fits nice with the cone of the Seas ER 18:

The paint was made by an professional car varnisher. I try it also, but the result was pretty bad.

They sound really gorgeous! Probably the best speakers I´ve build so long. Espacialy the bass is amazing, quite better than from ordinary vented boxes. The Fountek ribbons are also a highlight, I like them a lot.

I have also build the Speedster and the Microbe with Vifa XT:

Nice speakers and the Speedster are currently my #1, but for my new living room, I think the ER 18 MTM would be one of my favorites.

Finaly I had to thank Paul Kittinger for answering my questions immediately.

P.S.: Sorry, my english is not really good!

 

[Swerd]

Oliver

Thank you for your photos. Your woodworking skills are excellent, and your English is easily understood .

I'm glad to hear how much you like them.

 

[PatHoule]

Been reading lots of good posts on this forum! Very knowledgeable audio folks! These are sweet speakers. They will be my first item in my home theatre audio system. I will build these soon and post pictures when I do.

Are there plans for matching rears, center & sub?

I think Zaph Audio's ZA-SR71 could be the rear speakers.
Zaph|Audio - ZA-SR71

 

[PatHoule]

I have been reading lost of post on this forum. Great Info from great folks. These sweet speakers will be my first component in my home theater audio system. I will post pics when I start this build.

Are there plans for matching rears, center & sub?

The ZA-SR71 on Zaph audio site look like they would make good rears.
Zaph|Audio - ZA-SR71

 

[ARES24]

This is the matching center. Meniscus audio has a kit for it now.

I do not know of a 'matching' speaker for either rears or sides has been designed and a sub should be designed to suit the room IMO.

 

[milesguy]

Is the cabinet-only design off limits to commercial use? If so, would the protected party be interested in a royalty arrangement?

 

[fuzz092888]

Is the cabinet-only design off limits to commercial use? If so, would the protected party be interested in a royalty arrangement?

Yup, it is. The TL design belongs to Paul Kittenger and the overall design, including crossover belongs to Dennis Murphy. You could e-mail Dennis and ask at info@philharmonicaudio.com He's also a member here so maybe he'll see it and answer himself.

 

[jonas]

Hello,
I see this thread is a bit stagnant but thought I'd post anyway. I'm also interested in the ER18 MTM and am sourcing parts thru Solen since I live in Canada. Questions that have been rattling around in my mind are:
1) Any further listening impressions from builders/owners? I am leaning toward the dome version as my Ditton 662's are pretty relaxed sounding and this is what I'm accustomed to.
2) The posted crossover schematic (dome version) shows a series 15ga 1.5mH coil with DCR of 0.38ohm in the woofer section. Solen does not have an exact match for this and I am leaning toward a 14ga coil for this location with DCR of 0.28 ohm. Is a decrease in DCR of 0.1 ohm negligible for this inductor location? The alternative from Solen is a 16ga with DCR of 0.41 ohm.
3) Similar to question #2 is the 0.05mH inductor shown in the tweeter circuit. Thru Solen I can match the spec'd inductance and DCR but with a 20ga coil instead of 18ga. Any concern with a 20ga coil in this location?
Looking forward to any comments.

 

[ARES24]

Dennis mentions that any change in components that are within 10% of actual shouldn't make an audible difference. I'm no expert on coils but I don't think a change in ga will have any effect on performance, just capabilities. How hard do you plan on driving them? I still think the lighter ga would be ok.

<<not a physicist!>>

 

[jonas]

Thanks for the reply,
For the woofer inductor my concern, whether unfounded or not, was the decrease in DCR. From what little reading I have done on this subject, it appears that minimizing resistance in this circuit is beneficial. However, other reading also suggests that inductor resistance plays a role in achieving desired low frequency response thru electrical damping.

I hope you all will forgive my crude understanding and please correct me if the above is wrong.

Basically, I'm just wondering if the 0.1ohm decrease in DCR is worth losing sleep over.

 

[Swerd]

jonas - Welcome to AH and thanks for posting on this DIY design.

2) The posted crossover schematic (dome version) shows a series 15ga 1.5mH coil with DCR of 0.38ohm in the woofer section. Solen does not have an exact match for this and I am leaning toward a 14ga coil for this location with DCR of 0.28 ohm. Is a decrease in DCR of 0.1 ohm negligible for this inductor location? The alternative from Solen is a 16ga with DCR of 0.41 ohm.

I basically agree with what Ares24 said. The correct inductance value is most important, and 1.5 mH ±10% should be OK.

In your case, you can choose between at 14g and a 16g coil with the same 1.5 mH inductance but different DC resistance. Because the overall resistance of the circuit does matter, I'd choose the 16g coil. It's resistance of 0.41 ohm is closer to the original value of 0.38 ohms. But to be honest, I doubt if the 14 g coil with its resistance of 0.28 would matter enough to make an audible difference. Choose whichever costs less.

3) Similar to question #2 is the 0.05mH inductor shown in the tweeter circuit. Thru Solen I can match the spec'd inductance and DCR but with a 20ga coil instead of 18ga. Any concern with a 20ga coil in this location?

20g instead of 18g should not matter.

Good luck with your build!

 

[mattsk8]

Just wanted to chime in. I just came up from listening to mine and after however many years and hearing countless other speakers I still love the way they sound. Very much full range (unless you love bass, and I mean car audio style bass). They're incredibly transparent, and IMO it would be tough to top them in their price range. I have the ribbon version, and I still consider swapping to the the dome because if I had to dig, my only complaint is the highs are maybe a tiny bit too sharp. But I can't say if one is better, I've never heard the dome version.