RS180S-8 MTM Towers

[lamski]

Re: RS180S-8 MTM Towers

Depends what you are looking for. I believe someone has already built this same Jeff b design sealed to use as a center. If you don't have listeners too far off axis it should work well.

Do you have any additional info on this? I would be curious to read up on this sealed design.

[Mattcc22]

Re: RS180S-8 MTM Towers

Do you have any additional info on this? I would be curious to read up on this sealed design.

See post #114 here from CWAD8505...

http://techtalk.parts-express.com/showthread.php?223870-My-RS180-MTM-Design&p=1849716#post1849716

I don't see where he made much comment on how it sounds, but maybe you can see if he will comment
a little more.

[fbov]

Re: RS180S-8 MTM Towers

Thanks for the reply... If I recall corectly you were using the Nat P. on it's side correct?...

Yep; the toppled MTMs were both NatPs. Here's a more detail comparison. I started to learn DIY speaker design because I wanted a good CC, so keep in mind that the CC was the first one built. The first three versions were compared with Large Advent L/R, only the last two compared with NatPs. Here's a link to a post in my build thread from that time showing the LCR speakers being compared. The CC is clearly an "in-wall" application.

http://www.htguide.com/forum/showthread.php?30536-My-5-1-design-project&p=408221&viewfull=1#post408221

NatP MTM free-standing XO (same as towers; one of them got this XO)
Poor tonal balance, boomy compared with Advents. Not subtle to my ears. Learning curve for hearing was still steep, but this jumped right out. Turns out I'm sensitive to tonal balance and harmonic distortion, but not localized linear distortion (aka dips in FR).

RS MTM with Roman Bednarek's free-standing 2.5-way XO to reduce/eliminate lobing from the toppling
Poor tonal balance, very similar to the free-standing XO above. Verified 0.5 was working (one driver has muted highs), but it didn't address the tonal balance - the defect I actually was hearing - even as it eliminated lobing.

NatP MTM in-wall XO with reverse-polarity tweeter
Finally, tonal balance was restored, and panning pink noise across the front, there was some timbre variation, but nowhere near as much as before. Much better, but still with some degree of dialog clarity issues.

Fast forward several years, after buying a measurement rig, installing the Modula MTM CC, and veneering this bare-MDF speaker, I did FR measurements on this one and got the classic deep V of reversed tweeter polarity at the XO frequency, along with a rising top end. The latter resulted from a little "tweeter musical chairs" with RS28's, as my initial purchases were more sensitive than today's, so I've had to mix and match the 7 units I have, including a private purchase, to get equal pairs (NatP towers, NatP bookshelf, Continuum). That left this speaker with a tweeter that's too sensitive and needs a parallel resistor to tame it, as Jeff B. suggested when one of my Continuums had a hot tweeter (perhaps this one; I've lost track)... and figure out the XO error - mine in fabrication, or an oversight in design. I owe that tread a picture of what I built as folks were real helpful.

Also note that I upgraded AVR from an old Pioneer to an Onkyo 707 in this time frame... not a big difference in CC performance.

Modula MTM CC in-wall
This is the home run. I was surprised my non-audio wife mentioned the improvement in dialog, as she rarely says anything nice about my hobbies. Granted, subsequent analysis points to a deterministic root cause.... Comparing with the rebuilt NatP, I suspect it had a better-matched tweeter orignially, as this time, the NatP was sibilant and nasal. I watched about 5 minutes of Glee before swapping the Modula back in, so the high's wouldn't hurt any more.

Having lived with this one for nearly a year now, what amazes me is that dialog clarity is not a function of loudness. Very soft speach at low volume is intelligible. There are no obvious timbral defects when panning pink noise, as one might expect when the same mid-drivers are used, and the same designer voiced them. That said, narrow band defects are not my strength, so others may be able to hear things I don't...

Have fun,
Frank

[Mattcc22]

Re: RS180S-8 MTM Towers

Last weekend it rained almost the entire time, but it gave me time to work on the crossovers!

[lamski]

Re: RS180S-8 MTM Towers

Any updates on this? I would love to hear where you are at with these towers and the CC.

[Mattcc22]

Re: RS180S-8 MTM Towers

Any updates on this? I would love to hear where you are at with these towers and the CC.

I have the baffles close to ready. Still have to route the hole for the port and drill the screw holes. I've been really busy with the newborn and some other summer projects, but really want to jump back in on these speakers. I ended up buying a Hitachi plunge router and that has made things so much smoother than my dads old fixed base! I'll post some more progress pics soon.

[Mattcc22]

Re: RS180S-8 MTM Towers

Making progress finally!





It's coming together nicely.

[fezzywigger]

Re: RS180S-8 MTM Towers

Glad to see you are getting some time to work on these! I have been waiting to see some more on these. Can't wait to see more and hear how they sound.

[Mattcc22]

Re: RS180S-8 MTM Towers



Boxes are just about complete. I tested one of the speakers before doing the final glue up and from what I could tell so far in the garage, these are going to be a huge step up from the Polk 60's. I still have a little work to do on the bases and I have to make grills. I will probably go ahead and bring these inside soon and give some listening impressions. I am having a custom entertainment center built and my wife wants to wait until we have it in our house before we order veneer. It should be ready in another week or two hopefully.

[johngalt47]

Re: RS180S-8 MTM Towers

Whatever happened with this build?

[Mattcc22]

Re: RS180S-8 MTM Towers

Well, I have been using the speakers for quite a while now. We have had issues with getting our custom AV console built and actually finally just got our deposit back (had to threaten small claims court). Due to that the speakers still have no veneer and I haven't attached the bottoms. Sorry for the bad lighting...took these when I got home yesterday and it was already getting dark (hate the time change!).



As far as sound goes, they are much more detailed and much better sound stage than the Polk Monitor 60's they replaced. I did a little bit of AB testing before selling the Polks. Another big difference between the two was the realism and impact of the bass. I thought the Polk's bass was decent until I heard these.

[lamski]

Re: RS180S-8 MTM Towers

Thanks for the update. The bass is to be expected considering it's a MLTL design. I am looking to do something very similar if I ever get off my lazy *** and do it. That and I need to save up a bit more money for the project.

[blue934]

Re: RS180S-8 MTM Towers

Matt, I'm curious where you hi/lo pass the mains and sub on this combo.

David

[Mattcc22]

Re: RS180S-8 MTM Towers

In my huge room, and due to very limited placement options, I have a bit of a null or cancellation between 100-200hz. When I run the sub up higher to 150-200hz or so it fills in better but starts to get localizable, so eventually I want to try and add some MBM's to the system to see if that helps out. Right now I keep the crossover at 100hz to help fill in a bit better. I have listened to these full range in a friends house and they fill in very nicely and have a ton of clean bass so the problem is definitely due to my room.

[rexbass24]

Re: RS180S-8 MTM Towers

I have been searching now for a few weeks for the right speaker project to build. I was originally inclined to go straight up transmission line and adding a tweeter atop but I kept turning to the "core 2" designs that I kept coming across. That, in itself opened me up to the idea of MLTL and and dayton rs180. I came across your build after being obsessed with finding a dual driver design with the rs180's I thoroughly enjoy the look of that driver.

My question to you is, at the end of the day, are you happy with the sound imaging for all listeners across from the speakers? Or is it very centralized to be best at one focal location? I tend to sit in the sweet spot myself but my guests and children do enjoy listening to my system with me occasionally.

I really do want dual drivers to handle higher volumes and more power, but I am still undecided between your design and the core 2. Price mostly... is it worth the bit extra? I do have a Klipsch RW10D that I will use to slightly fill in. Speaking of Klipsch, I had a pair of RF-62 and was in love with them. Though, that horn was a bit bright. However, the detail in the mids and highs were amazing. Low end was a bit muddy though..

Thank you for sharing your build, it's been very educational for a newbie like me.