Nat.P vs. Dr.K MTM

[subynube]

I will be doing the DIY project Dr. K's MTM from the parts express DIY showcase. http://www.partsexpress.com/projects...mtm/index.html

Both the Nat P and Dr. K are MTM designs using the same 1.0 cubic ft enclosure from PE, and the same Dayton reference drivers. The main difference between the two are the port and the crossover. So essentially, they are both variations on the same theme.

My set up will be a 5.1 set up. Both front channels will be the Dr. K mtms, as well as the center channel. Dont know what the rear channel will speakers be. The receiver will probably be a high end Denon or NAD.

My question, is that I am wondering why was the Nat P developed if the Dr. K project was the original, and so similar. I believe the Nat P has some deeper low end extension, but is that the main difference? Is there going to be a major sound quality difference between the two? Other than the minor differences on paper, will there be much of a sound quality difference that is audible?

Thanks folks.

[Gir]

In a nutshell, Dr. K's design has some nasty valleys (-5db @ ~3khz and -6db @ ~18khz), while the Nat P is smoothed out a bit better.

[subynube]

Thanks Gir, would that difference be audible, or would this just be a difference noticed on paper and not much be ear? I would love to know if anyone has heard both versions. Thanks for the quick reply.

Edit: In addition, Dr. K does mention that one of these dips or "valleys" was built into the XO to achieve better off axis performance.

http://www.partsexpress.com/projectshowcase/dr-k-mtm/crossover.html

[ThomasW]

My question, is that I am wondering why was the Nat P developed if the Dr. K project was the original, and so similar

The NatP was developed not as a result of the Dr K MTM but due to requests for a lower cost version of the Modula MTM which was developed before the Dr K MTM.

[dlneubec]

I've built the Dr. K. MTM. It was my first DIY project a year and a half ago. It sounded good, but is certainly not the optimum for these drivers, IMO. I've not heard the Nat P. nor the Modula MTM to be able to do a fair comparison, however.

After a couple months, I rebuilt the Dr.K's with a 2.5way crossover for the RS180/RS28 designed by Roman Bednarek and thought that they were an improvement over the original.

[ahaik]

I had built the Modula MT, Microbe with the RS28, my brother did the MTM, all sound GREAT.
I don't really know about the Dr. K's MTM's, but what I do know is that I really trust the fellas over here at the HTGuide ;x( .
Asi.

[cjd]

I'm pretty sure the NatalieP also predates the DrK. At any rate, the projects posted up in the PE showcase are usually pretty simplified and not particularly optimized for sound quality...

C

[ThomasW]

Looking at things .....





The NatP with it's lower crossover point is going to filter out more of the grunge one sees as the RS180 plays higher..

There are a host of complementary designs for the NatP. These include in-wall/on-wall MTM and MT versions as well as specific center channel designs.

There is no center channel version of the Dr K MTM, and it's crossover certainly isn't designed or optimized for horizontal placement.

The so called "high-output" port design of the Dr K is irrelevant, since either of these designs should be used with a subwoofer when the intended use is HT.

[ahaik]

Roman has a page comparing all of those designs: http://www.rjbaudio.com/RS180MTM/rs180-rs28-mtm.html

[subynube]

Awesome, all great info guys. The last thing I really want to know is how the NatP matches up with Dr. K in real world listening. What the sq is described as with a listener in a room. Also want to know if all these differences on paper make minor differences to the ear, or if it really changes the whole tone of the speaker? It does state in one of those links that the NatP is usually preferred over Dr. K in real world listening.
I have already made the XO's for the Dr K (actually had Madisiond make them for me. Not totally DIY but they did a great job.) But if convinced, I will turn around and make the XO for NatP and go that route, if it really does sound better in a real world set up.
Thanks for all the help guys, this forum is awesome ;x(

[joecarrow]

If you're driving it with a good signal, then I'd say you would notice a difference. That means a reasonably powerful amplifier (just one that's not being pushed into distortion and clipping), and CDs or DVDs out of a dedicated player instead of MP3s out of a computer or portable player.

What might be fun, since you already have the Dr K crossover, is to do an A/B comparison with the Nat P to see if you notice a difference and have a preference. That'd put a little more Y in DIY, don't you think?

[subynube]

What might be fun, since you already have the Dr K crossover, is to do an A/B comparison with the Nat P to see if you notice a difference and have a preference. That'd put a little more Y in DIY, don't you think? [/QUOTE]


:lol: That is true. I really like this idea!!

[dlneubec]

I found the Dr. K's a bit shouty in the midrange, causing listening fatigue over a fairly short time period, if you have the level up very much.

If you look at the Simulated frequency response in the comparisons on Romans site, there is a signficant peak at aboyut 1.7khz, which could be the cause of that shouty quality. None of the other have this peak. The Nat P. is one of the flattest. If I was building it over again I would probably choose the NatP or the RJB 2.5way. I know I can hear the difference, since I compared the RJB2.5way with the Dr. K and easily preffered the RJB.

[joecarrow]

It's not even just the flat response that's responsible for the high performance of the Nat P- it's also the non-traditional filter that pushes the high frequency breakup even further down. Jon Marsh knows how to deal with metal cones, and he's done a great job taming them here as far as I can tell.

I build the Modula MTs, and they are the best balance of "mellow" and "detailed" that I've ever had. Just once when I had some of the parts but nothing yet built, I fed the RS180 some music without any crossover at all. Big mistake! I wanted to rip my ears off, burn the woofer, and burn my ears on on the burning woofer. I had no idea how horrible metal cone breakup could sound! Anyway, it's remarkable how thoroughly all that garbage is suppressed in Jon's design. The only time I hear something harsh is when I'm listening to music with lots of crazy distortion (some electronic stuff), or cymbal crashes at loud volumes.

I think that with the right songs, you'll notice a big difference in favor of the Nat P. The Modula MTM is even better, but I hear that it takes good equipment and louder listening levels for that to be apparent.

[dlneubec]

Very good point Joe and one I should have thought to mention as it was just driven home to me. I borrowed much from Jons approach with metal cones in my Mentor omni crossover design, which use the RS180's from 100 hz up and crosses to the RS28 at about 1.5khz. The slopes are about 8th order to get the trash WAY down low.

I just got back from the Indiana DIY and several attendees were amazed at how loud and dynamic they were, without distorting. Paul Kittinger was playing a orchestral piece on them and kept cranking it up and cranking it up. He came over after and said they were easily the best in the show and that they seemed to have unlimited dynamics. I believe this is significantly due to taking an approach similar to Jon's on the steeply sloped crossovers to control the metal cone breakup. No question, it works. Incidentally, the drivers in the MTM section of the Mentors are the original drivers from my Dr. K. mtm's, recycled into a new project! That says loads about how important the crossover approach is.

[ahaik]

Yes !! I agree with Joe, JonMarsh has over 25 years in speaker design and IMHO is as good as any of the best commercial designers. I remembering him saying once that the Natali is a better Bang for the Buck and the Modula is the most optimized for the dayton driver (thanks for the sharp elliptical filter). So the question is really Whether you want to invest the extra money for a little better performance (I did and very happy with my decision).
IMHO my Modula MT and my brothers Modula MTM sound considerably better then my Paradigm Reference Studio 100's V.2 (retailed for $2500).
BTW I'm using Parasound componnents to drive them.

[cjd]

Paradigm Reference isn't much of a bar to hold a quality speaker against. Unless you have a bar that's all harsh and spikey on one end, some elastic floppy in the middle, and just nerf on the other end. :P

[subynube]

Yeah folks, this is exactly the info I am looking for. I will probably do the Dr. K version now because I already have the XO, but will probably upgrade to Nat P at some point (when money allows) :roll:

[subynube]

dlneubec, When you went to the Indiana DIY festival, you said that many were amazed at how loud and dynamic "they" were. You mean the NatP?

[ahaik]

Chris,
Your response made me very happy and brings some closure to me :lol: .
My Brother and I also built your MTM's as centers (One for my brother and one for our parents) Very nice work, they sound great :T (Thank You ;x( ).
I am planning on selling those paradigm and building your WWMTM towers.
Was planning to ask you some questions about them, but don't want to hijack the thread (i'll save them for the towers thread).
Asi.
DIY = ;x(

[speedle]

Well, when you DO decide to upgrade to the Nat P, take the suggestion from a few posts above and rig up a way to relatively quickly switch out the x-over. You'll hear exactly what they mean that way!

[speedle]

Chris,
Your response made me very happy and brings some closure to me :lol: .
My Brother and I also built your MTM's as centers (One for my brother and one for our parents) Very nice work, they sound great :T (Thank You ;x( ).
I am planning on selling those paradigm and building your WWMTM towers.
Was planning to ask you some questions about them, but don't want to hijack the thread (i'll save them for the towers thread).
Asi.
DIY = ;x(

Well, not to perpetuate a hijack, but the Paradigm's are not ALL that bad. They have a "sound", but they measure very well and have filled my little ears with relaxed non-critical listening for a few years now. I've relegated them to HT duty (ironic, ain't it), and use my natalie p's for "serious" stuff with the good equipment.

[wkhanna]

As the beneficiary of Sir Jon Marsh’s (all hail and genuflect) superlative and generous work, I can tell you the Nat P’s will embarrass many commercially available speakers above the $2K mark. With that said, I would like to humbly make a suggestion.

Take the xo’s you now have and sell them on one of the DIY sites. Take whatever $ you get, beg borrow or steal the rest, and buy the parts for the Nat P xo’s. And don’t skimp, get good quality air core inductors, etc, and build them.

I am talking from experience, you will be putting a lot of personal time a effort into making these if you are serious, and when it is all done and said, a few extra $ for will seem insignificant compare to all your hard work. You will have NO regrets!

JMHO, but YMWV (your milage won’t vary)

[dlneubec]

dlneubec, When you went to the Indiana DIY festival, you said that many were amazed at how loud and dynamic "they" were. You mean the NatP?

Sorry for the confusion. No, I was talking about a pair of omnidirectional speakers I designed, but based the crossover concept on what Jon has suggested for dealing with metal drivers.

[subynube]

As the beneficiary of Sir Jon Marsh’s (all hail and genuflect) superlative and generous work, I can tell you the Nat P’s will embarrass many commercially available speakers above the $2K mark. With that said, I would like to humbly make a suggestion.

Take the xo’s you now have and sell them on one of the DIY sites. Take whatever $ you get, beg borrow or steal the rest, and buy the parts for the Nat P xo’s. And don’t skimp, get good quality air core inductors, etc, and build them.

I am talking from experience, you will be putting a lot of personal time a effort into making these if you are serious, and when it is all done and said, a few extra $ for will seem insignificant compare to all your hard work. You will have NO regrets!

JMHO, but YMWV (your milage won’t vary)

DONE!!!!!!!!!! Thank you all.

[wkhanna]

Saw your xo's for sale in the pawn shop section. I assume your perusing the Nat P. I have mine 98% finished and have been listening to them for the past few months. Don't hesitate to give me a PM if you have any questions.

[Jay_WJ]

Very good point Joe and one I should have thought to mention as it was just driven home to me. I borrowed much from Jons approach with metal cones in my Mentor omni crossover design, which use the RS180's from 100 hz up and crosses to the RS28 at about 1.5khz. The slopes are about 8th order to get the trash WAY down low.

I know Jon is a big fan of steep slope cauer-elliptic type filters when working with metal drivers. But I personally think his approach may be an overkill. Zaph used a much, much simpler, series LC notch filter approach for his L18/TBFCG and many people like it. I also used this approach to design an XO for RS180/TBFCG 2 way. With a lower xo point I was able to attenuate the twin breakups of the RS180 to a more degree than Zaph did for the L18. I'm by no means an expert, but the following quote is worth considering against the use of overly high slope filters. I read this article carefully and I think what the author says makes sense:

"With passive crossovers, I now believe that anything over 12dB is a waste of time, especially when the effects of voice coil temperature are considered.

Even with the second order filter, the possible variations (especially those caused by voice coil temperature) can totally ruin the sound - regardless of the quality of the components or care in making the crossover."

-- Quoted from Elliot Sound Products. The link of the article is: http://sound.westhost.com/lr-passive.htm

[BobEllis]

Rod sounds a bit jaded in that article. If you have the luxury of a tweeter that can work low enough to cross over well below the woofer's cone breakup peaks, you can get away with shallower slopes and possibly even avoid a notch filter.

The catch is how low can the tweeter go and still have acceptable distortion at peak levels? That's where higher order filters come in especially handy - keeping the tweeter happy.

The Nat P is a very nice sounding speaker even with next closest value inductors and standard tolerance caps. Perhaps tighter tolerances would make it more consistent build to build, but driver to driver tolerances are fairly loose and probably have more impact than crossover component tolerance.

[dlneubec]

I know Jon is a big fan of steep slope cauer-elliptic type filters when working with metal drivers. But I personally think his approach may be an overkill. Zaph used a much, much simpler, series LC notch filter approach for his L18/TBFCG and many people like it. I also used this approach to design an XO for RS180/TBFCG 2 way. With a lower xo point I was able to attenuate the twin breakups of the RS180 to a more degree than Zaph did for the L18. I'm by no means an expert, but the following quote is worth considering against the use of overly high slope filters. I read this article carefully and I think what the author says makes sense:

"With passive crossovers, I now believe that anything over 12dB is a waste of time, especially when the effects of voice coil temperature are considered.

Even with the second order filter, the possible variations (especially those caused by voice coil temperature) can totally ruin the sound - regardless of the quality of the components or care in making the crossover."

-- Quoted from Elliot Sound Products. The link of the article is: http://sound.westhost.com/lr-passive.htm

Hey Jay,

Maybe you caught me on a bad day, sorry, but this commentary seems pretty inappropriate to me. Jon has been designing and building crossovers for probably more years than you have been around (I'm guessing you are relatively young). To come on this forum, where he is a moderator and considered the resident expert and challenge what he does, with phrases like "may be overkill" and "overly high slope filters", etc., well you better have the chops for it.

From what I read on DIYAudio, you have done exactly one crossover design and have not even built it yet. I'm not sure how you can suggest you are anything but a novice (far from "I'm no expert"). http://www.diyaudio.com/forums/showt...threadid=99839 You seem to have no trouble in that thread suggesting that your first deisgn has it all over the Modula MT design saying this:

"Jon Marsh is not a fan of treble (as in the Modular MTM). In the original .75 cu ft vented box with a 17"x10'' baffle (i.e., less baffle step effect), this Modular MT is designed to emphasize midbass and midrange than treble. In a sealed box, as you can see in the above FR chart, the XO will emphasize only (upper) midrange. This might sound good to someone, but not to me! I like neutral sound and love treble."

Then here, you seem to blithely suggest that you did a better job of attenuating the driver breakup than Zaph, as if you think you are ready to compare yourself to him also.

Perhaps I'm overreacting, but this just seems way out of line to me and not a good way to be accepted on a forum you are relatively new to. Trashing other folks designs on other forums is also considered a bit unnacceptable. You do realize that many of us read all these forums, don't you?

Regards,

[Jay_WJ]

Yes, you're overreacting. Don't you read between the lines? The reason why I wrote the post, being aware that this is Jon's forum, is that I wanted to learn more!

If I were you, I would discuss the issue raised by the post rather than give a totally irrelevant, unscientific babble. If I didn't have sufficient knowledge to do so, I'd be silent.

[ThomasW]

Jay,

Here's a thought, instead of hijacking someone elses thread, start you own if you want to have a discussion regarding Jon's approach to loudspeaker design and engineering.

[Dennis H]

Yeah, Jay seems to have missed the D part of DIY. You know, actually build it and listen to it before deciding how it sounds....

[joecarrow]

Guys, lets keep it clean. We are all wrong eventually, and it's important for the sake of progress that we point it out to each other civilly on a case by case basis.

Design is an exercise in trade-offs, and while it may (I haven't verified that it is) be true that you attenuated your breakup peak further than Zaph did in the L18, he may have had a good reason for leaving well enough alone and not suppressing that peak further. It's possible that further suppression would have caused a net impedance issue that would have triggered a need for compensation that, when taken all together, would have greatly increases crossover cost. It's also possible that he just thought that his level of suppression was sufficient.

They are different drivers, so such a metric is really apples to oranges. The distortion profile affects how much the metal cone breakup is excited as well as the normal response. This must be considered in selection of the design- the RS180 has a broad breakup, where the L18 has more focused resonance. A wide range of frequencies will excite the RS180s breakup with their distortion products; this is less true of the L18- and just one of the many things that may have been considered during design.

I should also point out that Zaph came up with his L18 design a long time ago, before the RS180 even existed. It's one of the older designs on his main page. There's a pretty good reason that certain people have earned some respect around here, and people are more than willing to step in to say a word in their defense.

[dlneubec]

Yes, you're overreacting. Don't you read between the lines? The reason why I wrote the post, being aware that this is Jon's forum, is that I wanted to learn more!

If I were you, I would discuss the issue raised by the post rather than give a totally irrelevant, unscientific babble. If I didn't have sufficient knowledge to do so, I'd be silent.

Jay,

If you are truly here to learn, then you might want ot reconsider your approach. "Reading between the lines" I didn't see any call for discussion or desire to learn on the part of a noob, rather I see self aggrandizing statements of what you believe is fact. Not a good approach if you really want to learn or get advice.

While your at it, you might try to avoid critisizing designers in one forum, while asking for their help in the next. A little humble pie will go a long way.

[Jay_WJ]

Yeah, quite a few people responded as I expected. I did expect to see some hostile, uncivil responses. But I also wanted to see something useful that is worth me listening to in order to learn more (except Joe's comment---Thanks, Joe!). And I agree with Thomas that this is not a good thread to talk about the issue I raised. I'll start a new thread about it. I expect there something contributing to our better knowledge.

Joe,

You're right. Zaph's design is old, but as far as I know he still thinks that's a good design to build and I saw a number of people like the result of their build. One reason Zaph used a shallow slope with a series LC notch is that his intended listening axis was 2 inch above the tweeter axis and he found the natural off-axis roll off of the woofer contribute much to the attenuation of the breakups. And you're also right in that the L18 has a single dominant peak followed by less severe peaks whereas the RS180 has twin peaks. But I found that a notch centered between the peaks still attenuates the peaks well and can be effective when combined with a low xo point by a larger coupling capacitor.

[Jim Holtz]

Yeah, quite a few people responded as I expected. I did expect to see some hostile, uncivil responses. But I also wanted to see something useful that is worth me listening to in order to learn more (except Joe's comment---Thanks, Joe!). And I agree with Thomas that this is not a good thread to talk about the issue I raised. I'll start a new thread about it. I expect there something contributing to our better knowledge.

Joe,

You're right. Zaph's design is old, but as far as I know he still thinks that's a good design to build and I saw a number of people like the result of their build. One reason Zaph used a shallow slope with a series LC notch is that his intended listening axis was 2 inch above the tweeter axis and he found the natural off-axis roll off of the woofer contribute much to the attenuation of the breakups. And you're also right in that the L18 has a single dominant peak followed by less severe peaks whereas the RS180 has twin peaks. But I found that a notch centered between the peaks still attenuates the peaks well and can be effective when combined with a low xo point by a larger coupling capacitor.

Jay,

The responses you've recieved haven't been hostile or uncivil. They're straight talk. Here's the deal. You've created a simulation the way you think it should be done based on your research. The problem is, you've not proven it yet. Essentially, you're talkin the talk but you haven't walked the walk.

There are dozens of simulations available to build. Again the problem is, that's where you start, not where you end. Anyone with a little knowledge and free software can create a crossover. The masters build, listen, tweak, listen, tweak yada, yada, yada until it sounds just right to them. Then the design is made available to the masses for feedback. Often additional tweaks are made after that feedback.

The Modula M/T's have not only been built by many and been highly acclaimed for their sound quality in a budget class speaker, they've won top awards at DIY events in front of 30+ people in direct comparison to other comparable budget designs. That's the walk the walk part.

No one is getting down on you. You've just started in a fun and rewarding hobby. The point is, if you want to argue concepts and technical design with very accomplished designers, you need something behind you besides theory and an attitude.

Welcome to speaker design!

Jim

[Jay_WJ]

Jim, I completely understand your point, which I already considered and did not have any problem with in the first place. Not hostile or uncivil? Perhaps I used a bit strong words there. But again here I see another condescending word that wants to EDUcate a NEWb in his attitude rather than giving constructive, useful information. I just raised a question that may be worth considering. My intention was NOT to criticize Jon's design but rather to learn more by raising a question and listening to answers.

BTW, can you post your reply in the thread linked below if you have anything to discuss about the issue of voice coil temperature affecting passive XO performance? We don't want to use this thread for that purpose as Thomas suggested.

http://www.htguide.com/forum/showthread.php4?t=26211