Help me get this straight....

[Cdub]

Jon,

I've been following all of the threads on your various projects in their various stages of development. I just wanted to see if I got everything straight :wink:

1) Arvo dipole project
2) Saint Seans line array project
3) Center channel utilizing the Adire Extemis
4) MTM using the 8" Dayton with a "bass box" using the dayton 10"
5) and of course the M8ta...(can't wait to see the final product!)

Did I miss anything? Sometimes with so many ideas flying around in one thread I get confused :roll: I'm always interested in your guys progress on your projects. After hearing the MK IVs I was sold on my project

[JonMarsh]

Jon,

I've been following all of the threads on your various projects in their various stages of development. I just wanted to see if I got everything straight :wink:

1) Arvo dipole project
2) Saint Seans line array project
3) Center channel utilizing the Adire Extemis
4) MTM using the 8" Dayton with a "bass box" using the dayton 10"
5) and of course the M8ta...(can't wait to see the final product!)

Did I miss anything? Sometimes with so many ideas flying around in one thread I get confused :roll: I'm always interested in your guys progress on your projects. After hearing the MK IVs I was sold on my project

Well, that's pretty much it, but being a little subject to whim and modification as I go along, let me re-iterate and elaborate (gotta be true to that signature line, you know


1) Arvo dipole project - TC2+ woofers, M8a midwoofers, SS D2905/98000 tweeters - one completed pair in hybrid configuration (partial passive crossover, partial active crossover), one full passive crossover set in tweaking and re-assembly (had to send a set of defective 98000 back to Madisound).

2) Saint Seans line array project - RD50 line "quasi-ribbon", everything else somewhat up for grabs, although 8 Extremis midwoofers are ordered for initial evaluation. Considering 10" or 12" low mid bass drivers, possibly in W dipole, but may be push-pull H-frame instead. Most likely TC2+. Got 'em, and like them. After some more Arvo testing this month, may order TC2+ for this project. Looking at the current Madisound pricing for JP2's...

3) Center channel utilizing the Adire Extemis - Actually, the center channel concept at this time will probably use the Dayton RS180, along with the SS D2904/6000-01 tweeters. Trying to balance the cost and performance. Saving money on the LF drivers while still getting very good performance allows spending more on the tiny tweeters, and spacing drivers optimially for ~1400 Hz crossover.

4) MTM using the 8" Dayton with a "bass box" using the dayton 10"
- ?!? I never really planned to use the 8" Dayton for a mains style MTM, but rather, the 7". However, what's kind of gelled this last week is doing this MTM + bass bin as a bit of a homage to my X1 Klone project (which WILL get updated with 7" RS180 Dayton's); so, it will use the 1 cu ft. PE MTM box, with Peerless HDS 850439's (just happen to have a few lying around... doesn't everyone? and Focal TC120dx1 tweeters. Oh yeah, we have a few of the Focal's around, too, maybe 6-8. Why this combo? Well, the Peerless is the OTHER sleeper in the 6-1/2" to 7" midwoofer wars, except they're no where near as cheap as the Dayton's. Very good non-linear distortion and energy storage behavior. But they're about 88.5 dB sensitive, and two together will match up nicely to the 93 dB sensitivity of the TC120dx2. I'll have to do a couple of crossover variations, I guess, depending on whether they're used standalone (will have to have baffle step comp, reducing efficiency), or with bass cabinets (which will supply overlapped output from 100 Hz rolling to 600 Hz; the old X1 trick; so no baffle step required on the mid woofers). Bass cabinet could be dual 8" Dayton's, but most likely will be dual 10" Daytons, sealed. Overall efficiency will be in 93 dB/2.83V. Won't need a lot of power, but should really sing with a hundred watts or so. Should be pretty dynamic.... can you say, "Rock and Roll, hootchie koo?" Boy, does that ever date me.... :roll:

5) and of course the M8ta...(can't wait to see the final product!) - me too, I'm taking a week off around the 14 of December to work on these. I've updated the crossover design slightly since getting LspCAD 6; it's a little better impedance optimized, now. Note, because of the interest from other folks in building these, who can't get the Hales tweeters I have, I'm also doing an alternative network design for the Seas Millenium Excel tweeter. Maybe I'll use the Hales in some other projects.

6) The other Extremis project is something of an attempt at a somewhat budget oriented, but able to play loud and deep speaker like my daughter's system I built last year. This will be with the Extremis 6 in a 3/4 cu. ft. PE cabinet, most likely mated to an LPG 26T, which is used by some manufacturers of reknown, including, I believe, Aerial Acoustics. The 26T is about $39; not cheap, but very smooth on axis and 30 degrees off axis. We'll see if I can make the crossover work; I'm shooting for 1800 Hz. I'm not as sanguine about running the Extremis up above 2 kHz as the folks at Adire seem to be.... This won't be a very high sensitivity speaker (Hoffman's Iron lawy, you know), but it should be able to go fairly deep and play moderately loud, considering the cabinet size, and be pretty clean at reasonable listening levels.


OK, at this point, I PROMISE not to change any of these configurations for the next 30 days... by which time, 1, 3, 5, and 6 should be running. :B




~Jon

[Brian Bunge]

Jon,

Sounds like you've got some work to do! I'm really interested in seeing how the LPG tweeter works out with the 180's in an MTM layout. And of course I want the dual 8's or dual 10's in the bass bin section as well. Your description as "pretty dynamic" is right up my alley. Oh, and I know that Rick Dehringer song even though I'm only 33!

[JonMarsh]

Jon,

I'm really interested in seeing how the LPG tweeter works out with the 180's in an MTM layout. And of course I want the dual 8's or dual 10's in the bass bin section as well. Your description as "pretty dynamic" is right up my alley. Oh, and I know that Rick Dehringer song even though I'm only 33!

OK, I'll take that as another "request"- I did buy extra baffles for the PE enclsoures, so I can test several configurations.

This MT and MTM's are coming under the heading of a series of projects I did in the late 80's and early 90's which we called "Modula", for the modular approach to assembling a final speaker system. This is a new family which will be known as Modula IV; with a -1, -2, -3, and now I guess a -4!

Because of design commonality, the "effort" involved is reduced; plus I have much better design tools (and more experience!) than in the late 80s or early 90s- anyone remember CACD for designing crossovers with optimization on an IBM compatible PC? Yeah, that comes a bit before Sound Easy or LspCAD...

[Brian Bunge]

Jon,

I had it in my head that you were already planning on trying the LPG tweeter with the Daytons. If not, I'm glad I spoke up!

For clarification, could you please tell us what the other 3 tweeters are?

[JonMarsh]

Well, there's three other "configurations".


One configuration is an MT, with the Extremis 6 woofer and the LPG 26T tweeter.

Another configuration with the Dayton RS180's is optimized for center channel, by virtue of using the "mini" neodymium SS D2904/6000-01 tweeter, which allows spacing the drivers very close together in an MTM, and by virtue of that tweeters response, I'll be running a lower crossover frequency (with the cauer-elliptic filter like the M8 bookshelf or the M8ta or the Arvo Part).

The "HO" veresion is with the Focal TC120 tweeters; this could be built with RS180's or the Peerless woofers, but I've got four of the peerless sitting around (they cost > 2X the Daytons, but I didn't pay anywhere near that much).

In additional I'll do an MTM with the LPG26T and the RS180's. This is the real "budget" speaker in the lot, and I don't want to get "too" hopefull, but I think they'll really kick for what they'll cost to build. This version may only make sense in an MTM with normal baffle step compensation; otherwise, tweeter might not be efficient enough. The 26T is "rated" at 90 dB/watt, but seems to be more like 92/watt over most of the range between 1400 Hz and 15 kHz. If that proves out, then there are more options.

I'm also updating my X1 Klone upper modules with the RS180's. That should be cute. In fact, that will technically be a 5th option available (TS180's plus Focal TC120dx2), for anyone having access to TC120DX2's. There's a few still kicking around, and ThomasW is sitting on about 8 of them. Two are coming to me, for the build out with the Peerless 850439 HDS drivers.

I'm going to be swimming in speakers, but then I'm expecting to have three working systems at home by the end of December- a mini HT with my NEC 9PG+ projector, a pure audio setup in the living room, and the bedroom system, which will do both video and audio. Pretty sick, huh? That's what happens with your spare time when you don't have an SO, I guess.

~Jon

[Cdub]

Thanks for the clarification Jon! You are one busy poobah! I will be following your projects with great anticipation as I'm sure many others will be.

Out of curiosity, do the new Dayton RS drivers offer any particular advantage over the HiVi drivers for your M8 creations, or is it more of the fact that they are more readily available and at a more favorable price point.

Chris

[Brian Bunge]

Jon,

That'd be cool if the LPG would work out. In case you haven't figured it out already, I really like metal dome tweeters! If not, the XT25 would be fine as long as it'll work. Also, keep in mind that whatever I build will be a 3-way tower with dual RS 8's or 10's, assuming you're willing to pitch in a little more help.

And in case I forgot to mention it earlier, thanks again for all the time and help you've put in so far. I pulled out the AudioXpress articles from last year and was re-reading your methodology for using LspCAD. I think it will be very helpful in learning how to design XO's, especially from a modular approach.

[JonMarsh]

The non-linear distortion of the Dayton RS225 is lower than for the M8a below 150 Hz, and it has a longer Xmax (7 mm vs. 5.4) without any real performance penalty. However, the RS225 has energy storage issues lower in frequency than the M8a, and IMO shouldn't be used above 1 kHz, and only then with a very steep crossover.

The M8a are relatively available again, both through Parts Express, and now also Madisound, and Solen in Canada. Madisound also carries the M6a, which PE never had- it has a lower Xmax than the M8a, but longer than the M8n.

The Dayton's are hard to beat for the price, and with the very good distortion numbers (better even than a Seas W22 or ScanSpeak 8"), that makes them the driver of choice for 8" woofer applications where their limiations in the top end can be circumbented.

The RS180 7" Dayton's go higher, and still have excellent Xmax for a 7" woofer- 6 mm - and very low non-linear distortion. Beleive me, they DON'T perform like $30 drivers- they perform more like $130 drivers (think SS 7"). They're also a bit limited in top frequency crossover; I'd prefer 1400 Hz, and would go no higher than 1800 Hz.

~Jon