New DIY MTM Towers designed by Dennis Murphy and Paul Kittinger

[slipperybidness]

Flush mounted: does not hang over or protrude from the surface. Not change in outer thickness. Countersunk.

 

[Swerd]

Sorry for that. As You guessed I mean- change the faceplate in neo cd 3.0 from round one into a shape of rectangular or square/ like it is in NeoCD2.0 or NeoX 1.0.

The crossover was designed using the Fountek NeoCD 3.0 with a round face plate, 110 mm in diameter. If you use any other ribbon tweeter, a new crossover must be designed. This requires measurements of the new tweeter installed in an ER18 MTM cabinet.

I want to keep all dimensions ( and flat front of loudspeaker/ not like it is in 882/880- tweeter deeper than woofers), but I would like to move the tweeter in the middle in one vertical line.
I heard that there is some program that can calculate what changes should be made in original crossover, so maybe it will be possible without loss of quality in sound.

Moving the tweeter to the middle probably will not make a major difference in sound.

I don't know of any program that could predict what crossover changes might be needed. Only real measurements can do that.

Ps. Sorry for my english what do You mean saying "flush mounted"?

A "flush mounted" face plate is sunk into the front of the speaker cabinet so its edge is smooth with the front of the cabinet, similar to this picture:

 

[erpe]

Thanks for answers. I don`t want to use other tweeter, but original neo cd3.0. As it is show on the picture, that tweeter is sunk ( drilled with router), so I think that it should not be a problem if I will use new rectangular/square faceplate on neo cd3.0 tweeter, because it will only change the overal appearance of whole loudspeaker. It will also be sunk, so the whole front baffle will be flat( like in this post #47). Hope that I am right with everything.

 

[pgkhorn]

ER18 DIY Project

Hi Wow that is beautiful veneer work--what is it and how did you get it so perfect? I just heard a pair of Philharmonic 3 speakers and stumbled upon this thread when I researched them, Nice work Jeff!!
Pete

Here's my progress on the ER-18s. it has been a slow process. Two kids (2,5 and 10mos) and the younger one has been in the hospital a bit. Doing better now

My shop is usually messy this is a new low. Embarrassed to make it public.

My wife is sick so i was home to look after the stinkers today. Stole away a few minutes whilst they were locked in a closet. Just glued the baffle and base on the second speaker. Need to attach the binding posts, add the stuffing and mount the drivers. I have some floor spikes coming (back ordered until 6/15 or so). Might be listening to new speakers soon. Hopefully the xover is correct!! If anyone can make heads of tails let me know.

Soon....very soon...now for a new preamp-
Jeff

 

[pgkhorn]

Hi Swerd, I'm new to Audioholics and joining in late (by years) to this discussion but would love a copy of the PDF for these ER18 speakers. I just heard Dennis/Paul Philharmonic 3 speakers the other day and was BLOWN AWAY by the effortless sound. Agreed they use different drivers but since I can't afford them until I win the lottery, the ER18s seem like a nice place to start the new 2.1 system I have in mind. is there a Can I please also get a PDF of the plans? Thanks, Pete

 

[pgkhorn]

Hey guys,
Sorry for the lag to get an update posted.

I've been listening to the speakers for about 1 month now.
System:
-ER-18s
-Squeezebox 2 with modded PS
-MHDT Paradesia Plus NOS with WE 396
-YS audio Symphonies plus preamp with JJ tesla tubes
-ClassD audio SDS 254 amp (250 x2 into 4 ohms)
-cables-cheap Kimber and Cardas

I built the ribbon version.

The room is about 20 x 25. Not treated and too live. Bass is particuarly ragged lots of EQ on the IB sub). There is a HT bulkhead between the speakers (hindsight....). The ER-18s are about 1' in front of the font plane of the cabinet. My HT rig has an IB sub but this is not used for music.

Me- old (49 yo). Too many years playing music standing next to a ride cymbal (usually with cigarette buts in my ears). Prefers acoustic music (jazz, folk, etc), rock or classical. Played saxophone for many years in my youth. Well aquainted with what instruments and live music sounds like.

I feel like the strengths of the ER-18 are:
Neutrality- These are very accurate speakers in my estimation. Not bright. Not boomy.

Imaging- These things throw a great soundstage and instruments have are layered fron to back and extend wel past the speaker width. I love this about the speakers. To me, this is their best strength.

Vocals sound great. Natural and neutral and well integrated into the soundstage. Horns sound like they should. Brass has the appropriate bite. Mine are truly a little hot, but I know that is my room. I can hear lots of detail that was not evident before. There appear to be very revealing without being strident to my ears.

High WAF. They look nicer than others I was considering.

Other stuff-

Bass response- Not knocking down the doors, but adequate. The speakers play plenty low for acoustic music. To my estimation, at least 40 hz. They are not rattling the walls or moving copious amount of air. Bass is tuneful and tight. My room is pretty large (500 sq ft with 9 foot ceilings) but bass is certainly adequate for me. I'm sure a 3 way with a 10" or 12" woofer would fill things out better but that is not a fair fight. BTW, my port was 1/4" smaller than recommended and i cut is slightly shorter so my guys are not built strictly to spec. i like the bass but it is only a relative strength (for 7" MTMs) and not an absolute strength. Nice bass. no slam.

Overall, I really like these speakers. They best my Modulas (these are not optimally setup), they are better than the Zaph budget ($200) MTM. Should not be a surprise. I heard some $10,000 Thiels with NAD electronics (in a different room) that sounded crazy clean, although a bit sterile. I thought the Theils were significantly better (duh). Sorry for not having a more appropriate comparison.

I would build them again. My electronics and room feel like they are limiting the speakers at this point.
JG

Hi, great build! I'm curious which tweeter you chose for the ER18 the Fountec Neo-3 or the RS-28 dome from P-E? Thanks Pete

 

[Missionman]

Crossover Designs (by Dennis Murphy)

Dennis Murphy designed two versions of this speaker, allowing a choice between two different tweeters. Both designs have two ER18 woofers and the same cabinet, but one uses a dome tweeter and the other a ribbon tweeter. For each tweeter there is a different crossover designed specifically for it.

Note that the woofers and cabinet are identical for each design, but the woofer crossover sections of each design are also different. Schematic diagrams and parts lists for both designs are included below. The crossovers assume these details:

• Two SEAS ER18RNX woofers per cabinet, and one tweeter per cabinet:
Dayton RS28F-4 silk dome tweeter (total parts cost $551 as of August 2010)
Fountek NeoCD3-v2 ribbon tweeter (total parts cost $630)

• Follow all details of crossover schematic diagram. It is OK if the crossover components you purchase vary by ±10% from the specified values in the diagram.

• Use the driver locations on front baffle as described above in the cabinet details. Make sure the front baffle outside width is 9". All drivers are meant to be flush-mounted.

Some of the parts on the list, such as binding posts and cabinet spiked feet are my own personal choices. Feel free to change those if you wish, as they will have no direct effect on speaker performance. I priced the various parts (as of August 2010) with info from:

Parts Express (PE) Parts Express: the #1 source for audio, video & speaker building components
Madisound (Mad) Madisound Speaker Components: distributor of loudspeaker drivers and parts for speaker builders..

If you can get any of these parts at a better price from other vendors, feel free to do so.



ER18 MTM with Fountek NeoCd3.0 Ribbon Tweeter

Note:

• A 0.06 mH inductor was not available. I unwound wire from a 0.1 mH inductor until it measured 0.06 mH. In my hands, unwinding XX coils of wire was enough. I cut off the excess wire and sanded off the clear enamel insulation from the new end.

• I could not find a 50 Ω resistor. I used two 25 Ω resistors wired in series with each other.




ER18 MTM with Dayton RS28F-4 1" Dome Tweeter

• 24.7 µF capacitor – 20 µF and 4.7 µF capacitors, wired in parallel with each other, behave the same as one capacitor with a value of 24.7 µF. A single 25 µF capacitor can be substituted. Dennis said 24.7 µF looked slightly better in his computer simulation, but he doubts if 25 µF will be audibly different that 24.7 µF.

• The 0.5 Ω resistor in the tweeter circuit is real. I tried, without success, to find a smaller gauge 0.15 mH inductor coil whose extra DC resistance could allow me to eliminate the 0.5 Ω resistor.

Quick question...

Those er18rns drivers are 8 ohm's each... So I'm guessing with two of them wired in, it makes the speakers 16 ohm in total?
I barely see amps that are rated for 16 ohms

Cheers

 

[Missionman]

Anyone answer my question above?

 

[skyline_123]

Anyone answer my question above?

If you look at the diagram, it shows the drivers wired in parallel, not in series. The resistance adds differently.

 

[Swerd]

If you look at the diagram, it shows the drivers wired in parallel, not in series. The resistance adds differently.

Right. Two 8 ohm woofers wired in parallel, as they are in this design, will result in a 4 ohm impedance.

The predicted woofer impedance when mounted in the cabinet is shown in the solid red line in the graph below. It is easy to see that this speaker’s impedance goes no lower than 4 ohms. The tuning frequency of the cabinet, about 37 or 38 Hz, is indicated by the trough between the two red peaks.

 

[skyline_123]

Right. Two 8 ohm woofers wired in parallel, as they are in this design, will result in a 4 ohm impedance.

The predicted woofer impedance when mounted in the cabinet is shown in the solid red line in the graph below. It is easy to see that this speaker’s impedance goes no lower than 4 ohms. The tuning frequency of the cabinet, about 37 or 38 Hz, is indicated by the trough between the two red peaks.

Swerd, so when you're designing a speaker like this, do you look at the tuning frequency first or the predicted impedance? Or is it something you sort of do at the same time?

Edit: Post number 200! Moving up in the world!

 

[Swerd]

Swerd, so when you're designing a speaker like this, do you look at the tuning frequency first or the predicted impedance? Or is it something you sort of do at the same time?

Paul Kittinger designed the ER18 MTM cabinets using Martin King’s software. He is much more familiar with this software than I am, but I’ll try a general answer. To my knowledge, the overall impedance and cabinet tuning frequency were not primary design goals. But that kind of predicted info becomes available whenever you design a cabinet.

The software allows you to quickly see predicted bass response parameters in graphs when you enter the Thiele/Small parameters of a woofer. All the graphs shown in your 2nd post of this thread (under the subtitle Cabinet Design) were generated by Paul in this manner. This way, he could rapidly screen a number of woofers to see which ones give useful results.

I believe Paul’s primary goal was to get the flattest and deepest bass response from a pair of ER18 woofers in a reasonably sized cabinet. Dennis Murphy had already selected ER18s as his first choice because of their high frequency performance (in the crossover range), their cost, and he had a general idea that their bass response would be good. But he didn’t know what size cabinet was needed for good low frequency response. Why go through all the fine tuning if the cabinet will be impractically large?

Once that question was answered, Paul fine tuned the design by altering the cabinet height, volume, port diameter, length & location, even the amount of polyester stuffing, until he was satisfied with the predicted performance. Because he has used this software quite a lot, he already has developed a number of methods based on his experience and preferences that give good sounding results. In the right hands, like Paul, this software does a good job of predicting actual results – all without making any sawdust.

 

[erpe]

Hi there. After reading whole article I was thinking about building them like originals but I have a doubt. I have not needed fountek JP3 and I was thinking to use them instead of NeoCD3. In specification on fountek website recommendet crossover for bouth of them is 2500 Hz Fountek NeoCD30 Fountek JP3.0 .Do You think is there is going to be no problem if I will apply them instead of NeoCDs without making any changes in crossover?

 

[TLS Guy]

Hi there. After reading whole article I was thinking about building them like originals but I have a doubt. I have not needed fountek JP3 and I was thinking to use them instead of NeoCD3. In specification on fountek website recommendet crossover for bouth of them is 2500 Hz Fountek NeoCD30 Fountek JP3.0 .Do You think is there is going to be no problem if I will apply them instead of NeoCDs without making any changes in crossover?

I think you may have a problem.

The neoCD3 can be used with a second order crossover the JP3 requires a third order one and must roll off 18 db per octave at 2.5 K.

Whilst the crossover to the tweeter is a third order arrangement, the Q has been changed by putting a 2 ohm resistor in the T-filer in series with the cap and inductor. So this is no longer a straight third order 18db filter.

If you use the JP3.0, I think you have significant chance of damaging them if you use them.

I would use the ribbons recommended. I'm sure this is why they selected the ribbon they did.

 

[Swerd]

Hi there. After reading whole article I was thinking about building them like originals but I have a doubt. I have not needed fountek JP3 and I was thinking to use them instead of NeoCD3. In specification on fountek website recommendet crossover for bouth of them is 2500 Hz Fountek NeoCD30 Fountek JP3.0 .Do You think is there is going to be no problem if I will apply them instead of NeoCDs without making any changes in crossover?

I have to agree with TLS Guy about this. It may not work, and at worst, you could damage the tweeter.

As he described, the tweeter's high pass filter is a modified 3rd order electrical filter, that when combined with the NeoCD3 tweeter, results in an acoustic roll-in curve very close to a Linkwitz-Riley 4th order curve. That filter was chosen because a symmetric curve of similar slope could be done for the woofers at that crossover frequency. If you replace the tweeter, it is unlikely to work exactly that way.

On the other hand, it might work well enough. Perhaps you should email Dennis Murphy with this same question. You can find his email address at the bottom of this web page. Be sure to include the links you provided for both tweeters.

 

[djbachelor]

Sorry to post in such an old thread here, but I want to say thanks for pioneering the way with this "new" ER18 speaker design. Although not completed, I just got mine set up in the living room last week. (I know it's not such a new design anymore; As usual, I am several laps behind--I still have a set of Statement speakers halfway done in my cousin's workshop!)

I have a question about the flat response mentioned above; with my current setup (speakers plugged into an old Harmon Kardon AVR20ii integrated receiver, Nexus7 plugged into receiver) I am experiencing mostly awesome sound throughout the range except for an extra "boominess" or resonance in some of the lower frequencies... e.g. bass drum hits sound artificially loud and ringy on some tracks. Has anybody experienced this with the ER18s? (Somebody tell me if there is a more appropriate place to post a question like this, and others I have on placement for the ER18s and components for an appropriate 2.0 music system. I don't have enough posts to start my own thread yet.)

FYI: I built the dome tweeter version. Also, I am a long-time musician and music lover, but a novice at higher-end audio. Thanks for helping to spread the addiction!

 

[fuzz092888]

Sorry to post in such an old thread here, but I want to say thanks for pioneering the way with this "new" ER18 speaker design. Although not completed, I just got mine set up in the living room last week. (I know it's not such a new design anymore; As usual, I am several laps behind--I still have a set of Statement speakers halfway done in my cousin's workshop!)

I have a question about the flat response mentioned above; with my current setup (speakers plugged into an old Harmon Kardon AVR20ii integrated receiver, Nexus7 plugged into receiver) I am experiencing mostly awesome sound throughout the range except for an extra "boominess" or resonance in some of the lower frequencies... e.g. bass drum hits sound artificially loud and ringy on some tracks. Has anybody experienced this with the ER18s? (Somebody tell me if there is a more appropriate place to post a question like this, and others I have on placement for the ER18s and components for an appropriate 2.0 music system. I don't have enough posts to start my own thread yet.)

FYI: I built the dome tweeter version. Also, I am a long-time musician and music lover, but a novice at higher-end audio. Thanks for helping to spread the addiction!

This is a fine place to ask.

What room are the speakers placed in? Are they near the corners/walls? What are the floors made of? If the floors are hard are there any rugs? The lines (speakers) are properly stuffed?

It could be the recording, but sounds more like it is the room rather than the speakers from what you describe. More information will help nail it down.

 

[Swerd]

This is just the right place for posting your ER18 MTM build experience. Thanks.

And I'm glad to hear from someone who built the dome tweeter version. These are very good speakers. We need some more dome tweeter love here .

Although not completed, I just got mine set up in the living room last week.

I have a question about the flat response mentioned above; with my current setup (speakers plugged into an old Harmon Kardon AVR20ii integrated receiver, Nexus7 plugged into receiver) I am experiencing mostly awesome sound throughout the range except for an extra "boominess" or resonance in some of the lower frequencies... e.g. bass drum hits sound artificially loud and ringy on some tracks. Has anybody experienced this with the ER18s?

Like fuzz, I have several questions:

1. Did you install the 16-18 ounces of polyfill in the upper 22" of the cabinet? I haven't heard these speakers without the polyfil so I can't be sure what difference it makes, but the design definitely calls for the polyfill.
2. With bass tones, moving the speakers or the listener to different locations in the room are known to make big differences in the sound. Now that you know a musical passage that excites the extra bass resonance, play with the speaker location and see if that has any effect. If its due to room location, you know what to do. If not, it may require some more work (see polyfil above).
3. Finally, what speakers were you previously listening to? And how did they sound with that same musical passage with the bass drum? If you were accustomed to their sound, switching to different speakers will always be noticeable.

… but starting with a simpler and less expensive build would have been a positive and valuable experience. I had my heart set on these coming out 'perfect' for the living room, so each little mistake has been kind of stressful.

Every builder makes mistakes. And they can always point them out to anyone. Remember that most or all of these mistakes will never be noticed by anyone other than yourself.

 

[djbachelor]

Thanks for the quick replies and support. Yes, I think the dome version sounds great-- I am very pleased (with most recordings so far) with the clarity and smooth nature of the higher end. The setup is in the upstairs living room--fully carpeted, but with big windows, mirrors, brick fireplace, flat ceiling...dampened by the carpet and couches, but that's all. It is open to the rest of the house. I could post a pic of the environment when I figure out how. One of the reasons I selected the dome version (other than for a little variety from the Statements which will eventually be in the theater room) is that we plan to put down hardwood in this room later on, and I thought that would brighten up the highs quite a bit.

They are a couple feet away from the walls (side and back), I have played around a bit with placement and angles, but not extensively yet-- and again, I don't really know what I'm doing so it is more trial-and-error. The cabinets have the polyfill in the top half, but not carefully placed--I just roughly divided the 32 oz bag from Meniscus. If I didn't divide it evenly, one of them might be under-dampened; and it sounds like I could put a couple more oz in each anyway to stay in spec.

I also haven't put the foam tape around the drivers to seal them in, but I would expect audible effects to sound different than what I'm experiencing. When I take them back out to the shop to do the finish work, I will of course install the foam tape and measure out the polyfill carefully.

Previous speakers were little Denon M37 bookshelf speakers sitting on stands in the approximate locations of the ER18s. Not too bad for little bookshelf speakers--but no surprise that they didn't have problems with too much bass.

One more strange thing about the room which could be having an effect, now that I think about it--there is a 3' across, 45 degree shelf built into the wall in one of the corners behind the speaker--i.e., the speaker is not standing in a square corner, but rather close to a 45deg panel (floor to ceiling including the shelves) which would do who-knows-what to the lower frequencies and reflections.

 

[djbachelor]

Ah, another small detail with my build selection (I will just keep rambling until I am up to my 10 posts to start a thread!)--I must admit that I have trouble with commitment, and I did have some trouble deciding between the ribbon and dome tweeter: as such, I used the dome but left the extra 1/10" space when placing the woofers, so that I could switch to the ribbon down the line if I really wasn't happy with the dome. I am quite sure I will never do this, but I like to keep my options open.

I did not believe that that .1" compromise would have any audibly negative effects, though...