Center channel using M8s and XT25?

[PMazz]

Any advice for making a CC to go with my brother's MTMs? ......and maybe one for myself

I always thought that moving the woofs as close together would help comb filtering for a MTM CC. Would the standard xover work OK?

Pete

[JonMarsh]

Push those 8's right together, then nestle the tweeter in one of the sides as close as possible (probably the upper side), and that will be the best you can do with those components. Should work fairly well, but I expect that the MTM CT I'm developing with the RS180's and Scanspeak D2904/6000-01 will be a bit better still, because the woofers are smaller, and the tweeter can nestle closer. I'll have the first set working in December, SB before Xmas. Got pretty much all the bits- cabinets, drivers, etc.

Can you wait for a report until then?

[PMazz]

Since I was thinking about the RS 7s or 8s for the LA, I guess I could pick up a few more .

Hmm.....Sometime in December.....I guess I can wait since we're already in December.....Are you sure you meant this year Jon? Have you looked at your schedule at work?

Hell, I have plenty to keep me busy. Still haven't touched my brother's MTMs. In case you haven't seen my latest project......http://home.comcast.net/~bcwwkg/birt...dia_center.htm

Pete

[JonMarsh]

In Houston today, Austin this afternoon, then fly to Dallas.

But all next week I'm off, and the following week I only work three days! Can you believe it? :B

Yeah, I'm talking December 2004, not 2005!

Heck, I'm even planning on going to the Rockler store this weekend!

~JOn

[JonMarsh]

BTW, great work on that media center project! You can come build me one any time you want! Nice install on the new subs... :T


~Jon

[David Meek]

Hi Jon, I waved as you went by. :later:

[David Meek]

Pete, won't pulling the mains in that far impact your soundstage and imaging? Beautiful speakers BTW.

[Andrew Pratt]

What would happen if the drivers were on an angle and the tweeter in the middle sort of like this.../-\ for surrounds? Would the XO's still be the same as regular MTM or at least close enough for surround duty?

[PMazz]

Pete, won't pulling the mains in that far impact your soundstage and imaging? Beautiful speakers BTW.

This has been my dillema. To build the speakers in, or not. I love to listen to music but quite frankly, don't just sit and listen anymore. I'm always doing something else it seems. I went back and forth over this and finally decided to just do it. That of course means losing the dipole alignment and building them into "boxes".....ugh! I still cringe. At least they will have room to breathe. The enclosures will be ~13" wide x 75" high and 28" deep. I'll probably put in a divider to prevent the back pressure of the woofer line from affecting the RD50s. This was a very tough decision for me to make, but once I decided to do it, I feel better about it. Time will tell, as will the final sound, since I've gotten quite fond of dipoles.

Pete

[PMazz]

What would happen if the drivers were on an angle and the tweeter in the middle sort of like this.../-\ for surrounds? Would the XO's still be the same as regular MTM or at least close enough for surround duty?

Not sure I'm following you here.....or if it was even directed at me????

Of course I'm not sure of much these days...

Pete

[PMazz]

PE has the RS 180s on special, BTW.

I think Santa will just have to bring about 16 of the wee beasties for Xmas! I'm going to go ahead and order them.

I guess I should go ahead and order the SS tweets too. That is as long as you're sure about the driver selection.....Jon, are you sure, or should I just wait?

Hate to pin you down on this but free shipping hangs in the balance!

Pete

[PMazz]

Nice install on the new subs...

Yea but Tom won't let me become a member of the Cult unless I remove the fiberglass. Sheesh, some guys are really picky.....and I thought I finally could join! I was really looking forward to learning the secret handshake.

Pete

[ThomasW]

Nope, no "Cult" membership until you build an IB, not an aperiodically loaded cabinet :wink:

Later this month I'm going to buy one of the new little Maggie MMG-C to try it out as the center for my planar rig. I hoping that I can stack 2 or 3 and get good output. That might be something for you to consider Pete, to match your RD-50's.

[JonMarsh]

PE has the RS 180s on special, BTW.

I think Santa will just have to bring about 16 of the wee beasties for Xmas! I'm going to go ahead and order them.

I guess I should go ahead and order the SS tweets too. That is as long as you're sure about the driver selection.....Jon, are you sure, or should I just wait?

Hate to pin you down on this but free shipping hangs in the balance!

Pete

Are you talking about the SS D2904/6000-01 when you referto SS? I'm measuring shortly, and Mark K is doing some detailed Praxis work for non-linear distortion and energy storage (I sent him a bunch of tweeters to test last week- he hopes to get it done this week)- we're both curious if this little works as well as it's big brother. From the published data, I think it looks pretty safe (that's why I ordered some), but I understand wanting to see "where's the beef". They're in stock at PE and Madisound.

I don't know of a better tweeter for this application (requiring small driver diameter and tight spacing), and for myself and an old friend locally, this is what we're going to try. Will probably need to build 4 of these CT's before we're done; he needs two, and so will I.

~Jon

[PMazz]

Are you talking about the SS D2904/6000-01 when you referto SS?

Yep. Maybe I'll just pick up a set to do my CC and hold off on my brothers. I'm currently using an Eros MTM and promised my nephew I'd build him a set of mains with those parts and another set I have laying around at the shop.

Tom, sounds very interesting. I may have already confined myself to using a standard design tho. I'll be curious what you think about them.

Pete

[ThomasW]

Pete,

I've used a conventional cone/dome system as my center for quite sometime. Unfortunately there's a big timbre mismatch between it and the RD planars. At times it's quite distracting and bothersome.

[PMazz]

Nope, no "Cult" membership until you build an IB, not an aperiodically loaded cabinet :wink:

Later this month I'm going to buy one of the new little Maggie MMG-C to try it out as the center for my planar rig. I hoping that I can stack 2 or 3 and get good output. That might be something for you to consider Pete, to match your RD-50's.

Now why didn't I think of that???? Hmm, 36"w x 9"h x 5"d......damn, that would fit up there somewhere.....would have to mount it right up to the soffit, but it seems that's what they're designed for..... 8) I'd only be able to use 1 of them tho, so I'd be curious if you think they're worth a try.

In the mean time I ordered 14 RS 180s for the LA and CC (now out of stock), along with the SS dome tweet. If the Maggie CC works out, I'll have everything I'll need for my brother's CC and I'll tell him he has you to thank.... :T

Pete

[Mark K]

SS6000 looking pretty good!

[JonMarsh]

Hey, good news, Mark! I had my fingers crossed for that one.

Monday, I'll have to get some 27TDFC's on order to play with... thanks for the tip. Just getting through some of my mail...

~Jon

[Brian Bunge]

John,

I've heard a few DIY speakers in the last couple of years using the TDFC's and was extremely impressed with their sound, especially considering the price. If that unit works well with the RS 7's that would be a great way to go.

BTW, I started to jump on 4-6 of the RS 7's but realized the difference between the $25 price and regular dealer price was less than $2 so I figured I'd wait until things were a little more "comfortable" money wise. Speaking of which, I had a great interview this past Thursday (2+ hrs.) and the guy asked me to come back in this coming Wednesday to discuss things further.

[JonMarsh]

Congratulations on the good interview!!!!!!!!

Hope that works out!

Yeah, the TDFC's just may be the sleeper tweeter of the year from Seas. I was comparing the performance curves with the $75 dollar Excel models, and that's really got me scratching my head. Mark's been doing some great test work, and let's just say I think there's going to be a run on those little Seas for new designs.

OTOH, I was hoping the SS 6000 would look good for my planned CT design with the RS180s, and it looks like that will come together, based on Mark's test results. I'll be setting up baffles to test some time next week.

Same position as you on the price- the timing and shipping is a bigger deal. I'm swimming in drivers and projects right now, but it's kind of cool; looking forward to getting some stuff done in the next few weeks.

I'll cross my fingers for you....

~Jon

[Brian Bunge]

Thanks, Jon. It's basically a technician position with the hopes of a promotion into management within 3-6 months. The owner just wants to make sure that the person he hires learns the product before sticking him in a position where he'll be scheduling installs, talking to customers (doctors), builders, etc.

If you like the 27TDFC's that's probably the route I'll take. BTW, I picked up a pair of those new little 3/4" Dayton tweeters that sell for around $5. They're just so cute I couldn't help myself. I figure they may work well mated to little 4" woofers for tiny little mini-monitors.

[Evil Twin]

Four 27TDFC's have been ordered and should be available for evaluation by the end of the week.

Mark K says the force is strong in this tweeter....

[Mark K]

Four 27TDFC's have been ordered and should be available for evaluation by the end of the week.

Mark K says the force is strong in this tweeter....

More than you can imagine. It is this tweeters' destiny, along with its brother, the 27TDC, to rule the audio universe.

My analysis of the Death tweeters are complete

[Evil Twin]

More than you can imagine. It is this tweeters' destiny, along with its brother, the 27TDC, to rule the audio universe.

My analysis of the Death tweeters are complete

The Emperor's Grand Moff for driver testing has spoken... heed well his wise words and comprehensive test data.

[Steve Goff]

Perhaps the most interesting finding is that the 27DTC keeps up with the Millenium at low frequency nonlinear distortion and beats it at high frequency distortion.

[Evil Twin]

Yeah, makes me wonder if the Excel was completely "right". They're fresh from Madisound, though, never run elsewhere.

Unless there's some other factor to their sound that gives the Millenium a nod, it's certainly puzzling.

[Mark K]

Incidentally, I did some tests on the Hales before I send them out. I kind of wish one of the domes didn't get dented because, well, these are up there as some of the most spectacular tweeters I've tested so far. I haven't compared each and every graph, but they certainly fare very, very well. In the same league as the xt19/9700 in the high frequencies, and in the same league as the 27TDC's on the low end.

Like I said, not sure if the best, but definitely on the medal platform.

You sure you don't want to sell me one :B

[JonMarsh]

Mark,

Tell you what- you've really helped out with this testing. And I have a pair with one with a dinged dome, too, that I rubbed back out (you know, those body shop skills come in handy sometimes).

You've been a real gentelman and a scholar with your testing for the DIY community. :T :thanku:

:amen:

So, I'll just send you a good one for Xmas, then you'll have a nice matched set, and I'll still have two fully funcitonal pairs for my own death speakers.



:dothewave:


~Jon

[Dennis H]

One thing I noticed, the Millennium has twice the Xmax of the others, with a bigger gap for the underhung coil to move in. Maybe it really starts to perform at higher volumes? Or maybe not. Thanks for the testing, Mark!

[Davey]

Yep, I noticed that too. All other things being equal an extra 6db or so max SPL with the Millenium?

I also noticed the Scan-Speak drivers 9300, 9500, 9700, all have similar Xmax figures (0.4mm).....with the notable exception of the 9800 metal dome tweeter. It has considerably less Xmax.

Davey.

[JonMarsh]

Yep, I noticed that too. All other things being equal an extra 6db or so max SPL with the Millenium?

I also noticed the Scan-Speak drivers 9300, 9500, 9700, all have similar Xmax figures (0.4mm).....with the notable exception of the 9800 metal dome tweeter. It has considerably less Xmax.

Davey.

I would hope the Millenium would have something extra in reserve... but Mark's tests don't really show that. Well, they look really trick; I'm sure I'll figure out something to do with the pair I bought so they coudl be tested.

Regarding the 9800, vs the other SS, I don't trust "specs" much anymore- the 9800 doesn't "test" like it has considerably lower Xmax... one reason I've used it, besides the sound, and relative crossover interchangability with Vifa XT.

Oh well... it's been an interesting month so far, and only half over. Gotta get back to my veneering.

~Jon

[Evil Twin]

So, which is the real contender?




Brand "S" on the left, for $28.50, or Brand "S" on the right, for $159.50?

Considering that the one on the left recorded comparably low distortion in the low end, and better performance in the high end, it is clear that there's something strange going on in Norway...

Though the one on the right is clearly made with attractive packaging, handsome is as handsome does.

[ThomasW]

Ya know, us Norwegians aren't really partial to 'the Danish', unless they're the baked kind one eats for breakfast ..... :wink:

[Davey]

It's curious Jon. Is the specification incorrect, or does the 9800 tweeter really have considerably lower Xmax? If so increased distortion would seem to be the result. Maybe this explains why you like the sound of the 9800?

There's no doubt the 27TDFC is the better value relative to the Millenium, but I've listened to both now for a considerable amount of time and there's also no doubt the Millenium is the superior tweeter. Construction is a part of the cost difference. The 27TDFC is plastic everywhere, whereas the Millenium is definately not.



Cheers,

Davey.

[JonMarsh]

I've heard the Millenium in several systems, though not the 27TDFC, yet.

The construction differences are pretty obvious- but, for example, the way I build most speakers, the back of the tweeter is not open to the woofer rear wave, so the mechanical strength isn't much of an isuse- and as "plastic tweeters" go, I have to admit the 27TDFC is built pretty decently.

How would you characterize the difference in sound? Have you compared them in the same system design, with roughly the same crossover point?

This is more than an intellectual question, as I'm working on a design right now for a friend, who could afford the Milleniums, with a little effort, but I'm having trouble justifying to him the added expense- not that it matters to me, I'm just preparing the design, he's buying all the parts. But $125 a side covers a lot of other parts... so your comments would be very welcome.

I've also looked at the off axis behavior, and it looks pretty similar between the two- not surprising, as the domes seem to be essentially identical. I use the word "essentially" because I realize there could be some material difference; it just isn't obvious to the naked eye.


~Jon

[Mark K]

I'm interested too, genuinely. But after you look at FR/power/nonlinear, and transient response, well, I'm open to other methods of evaluation.

Believe me, I've bought a raven and a G2si, multiple planars, two pairs of hiquphons, and a boatload of domes. I've learned alot and spent alot of my own money on drivers that don't seem to perform as well.

So I think there is some burden on someone else to offer an alternative hypothesis why some of the expensive drivers don't test well.

I mean, they could just be jaguars, right? Except, of course in the case of the Milleniums, at least they are built well.

It also depends, a bit, on how you look at it. If you strictly look at second and third order products, the millenium is one of, if not the best. A case could be made that it edges out the others.

No doubt higher order products are more notable in the millenium. But it may have better tranient response/linear distortion due to it's more open motor.

Still, at five times the price you're at best getting an incrementally better tweeter. And even then, you have to assume there is something my tests aren't capturing.

[PMazz]

Interesting stuff! It does beg the question "So what makes one driver sound incrementally better than another, if they measure similarly?" I myself seem to always prefer a slightly rolled off top end, no matter what speakers I've built.

On another note.....My PE order arrived, all but the RS180s of course. PE states 30 days, we'll see. I see why that tweet interested you for a horizontil MTM. It's small footprint seems ideal.

Pete

[Davey]

Jon,

Inquiring minds still want to know. Is the +/- 0.1mm Xmax specification on the 9800 accurate or not? The Seas and other SS drivers have Xmax specifications ten times that amount. What am I missing?

Davey.

[JonMarsh]

Based on the LF performance and distortion I've measured on that tweeter, I don't believe that spec can be accurate, as the performance otherwise seems comparble to drives like the D2904/6000's I have.

But then I've had issues with SS specs in the past... especially measuring small signal vs. large signal T/S parameters on their midwoofers. But that's another whole topic.

But speaking of inquiring minds want to know, how about your comments on the sonic character of the 27TDFC and Millenium Excel? Just curious...

~Jon

[Mark K]

Oh, I kind of hate to do this, but...

I'm sneaking a for sale ad in here.

I've got 2 brand new, or like new, I guess , M8a's and an M8n. All in 9+/10 condition, that I need to get rid of. If anyone is interested email me.

Thanks.

$75 for the pair of M8a's. $20 for the single M8n. $85 gets all three.
Plus ups shipping.
US only.