A new home for the BG ribbons?

[Hank]

Jon, thanks for the concise comparison. As I read it, I was thinking: "alright, some differences and associated issues to deal with , but looks like monopole is okay". Then I got to: "...usually better imaging" in the dipole pros section. Hmmmm....
The NEO 8's in Danny's Alpha LS are a monopole implementation. the NEO's are backed by a separate long isolated chamber that's filled will absorbtive material. The imaging of those Alpha's was great, so I think I may stick with monopole.
That brings up my quandry. I was leaning towards RD-40's monopole with no mid-woofs alongside, but a stack of two 10" below the RD/enclosure.
Are you saying that this implementation won't work too well because:
1. A stack of two woofs is not enough to qualify as a line source, and/or
2. The woof line source must be parallel with the mid/tweet line.

Looks like this is the final big question leading to my basic configuration decision.

[JonMarsh]

Hi Hank,

No, two woofs does not a line source make. Thinking you are correctly in this, says Yoda.

However, depending on your room size, the variablity of your listening distance, etc., it may work for you... as long as the system is tuned for your setup and listening distance.

But, IMO, it will have the same drawbacks that the other implementations like the Soundline and Newform have- there's just no similarity in the wave launch at the crossover between two tens stacked *under* a RD40 and the RD40 itself, so integration in the crossover region, as well s the fall off and radiation pattern, are going to be a problem.

YES, the packaging concept is attractive- heck, that's why even companies like Martin Logan do this. YES, it can be tweaked and tuned for acceptable in results in the right size room and at a certain listening distance.

YES, the stregths of the RD driver will tend to obscure (at least initially) the issues in integration and top to bottom coherency.

And that may actually meet your requirements, and be the best compromise for you.

BUT, I wouldn't be your friend if I didn't point out the issues and potential drawbacks, and what you might have to gain with a better implementation. But the balance of sonics, cost, and esthetics is a very personal one, and to meet your blend of requirements, only you can make the decision about what is the best tradeoff.

BTW, another simple test, re dipoles vs. boxes; go to a dealer that carries Maggies and B&W, for example; or find one for each in your area. Take along some music you're familiar with. Play the music on each system. Listen at a normal listening position, then also, while the music is playing, go up and walk around and behind the speakers while they're playing. You can substitue Martin Logans or another good dipole speaker if you can't find a local Magneplanar dealer, but I think there's more of the latter in the US, and they are dynamic, just for reference.

I think you'll find that interesting.



Regards,

Jon




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We'll screw up the other planets later....

[Hank]

Jon, thanks and I do understand what you're saying. After installing all the drivers in the GR Alpha LS's, we set them up in my empty living room (that's where the photos on GR's web site were taken), and Danny tweaked the location/placement until he was satisfied. I tell you, they sounded great and the soundstage was all I could hope for. BUT, the are huge and really dominate a room.
I don't want to design/build a speaker that is limited to one exact distance placement - I'll be moving to another house some day - so, it looks like the slim RD or NEO tower on top of a bass cabinet is not doable for me.
Maggies do sound great. BTW, I toured the factory while on a business trip to St. Paul. I called up and when I said I was on a 3M business trip, the guy said: "My dad developed the concept while he was an engineer at 3M - come on over and I'll show you around". He showed me everything. The company is a real entrepreneurial success story.
Question: What about using 6 1/4" or 6 1/2" woofs alongside an RD40 or stackof NEO 's instead of 8" woofs? That would allow a bit narrower cabinet. How many? And, of course, what make/models would you recommend?

[JonMarsh]

Hi Hank,

6-1/2's are tricky. Most don't have much Xmax, (with the smaller Sd, sensitivity would suffer too much), and it would take a good size stack. Get's expensive if they cost much each.

As I mentioned previously in this thread, the MCM cast frame carbon fiber driver looks interesting for "cheap". It uses a frame and vented flat spider design that is more typical of SEAS than what you usually see from Taiwan. It's still on my list of "to-do's" to make an "inexpensive" line array experiment with this driver and the Neo8's, monopole as you say. When you go dipole, the excursion and Sd requirements for LF output make any 6-1/2 that I've seen a questionable choice. There are many other fine drivers out there, and lots of Vifa and Seas 6-1/2's that are popular with the more conventional DIY crowd; you could probably get more feedback from them. I used some of the classic SEAS 6-1/2's, like the P17REX back in the 80's, but I haven't messed with them since. The driver Danny uses, whatever it is, looks well made.

If I was combining the Neo8's and the MCM's, I'd use about a 750 Hz crossover, high order; this is a low enough frequency that the center to center distances of the array's wouldn't present any lateral dispersion issues at the crossover frequency.

The 4+ price of the 55-2321 is $22.50, so 18 of them is only about $400. They could be used with an RD driver with a fairly low frequency, low slope crossover. Just remember you'd have to deal with baffle step overall, still, at a frequency dependent on the size of the front panel. If you did measurements of them in the enclosure, I could design some crossover options to get started on pretty quickly. I would need data that can transfer to LspCAD, such as from a CLIO system.

With something shorter like an RD40 or RD50, six or eight driver's a side might work fine.


-Jon




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[Hank]

Thanks Jon. I have the MCM driver spec sheet on its way to me. I was thinking about Danny's 6.5" driver, #GR165. It's Xmax is 4.5mm, not too shabby and the curve looks pretty good.
FS 39.5 Hz
RE 10.85 ohms
Qms 2.52
Qts .53
Qes .67
Xmax 4.5mm
L (1k) .34 mH
L (10k) .62 mH
Vas 36.26 Liters
Ms 11.91 grams
Cms 1.374 mm/newt
Bl 6.89 Tesla-M
SPL 87.5 db
Area 137.07 sq cm
I could probably get them for less than the MCM's. Whaddaya think? Also, I can be flexible with the baffle. I have an idea for a "different" enclosure shape (hey, I have to have something to put my signature on )
So, 6 NEOs or RD40 and 8 6.5"ers might be the final design.
I'll have to let it stew for a few days.
NEO's or RD's...NEO's or RD's...
Or, I could wait for you guys to build a stack of NEO's and get your opinions. hmmm...

[PMazz]

Given the near field/far field transition of a line array at a given listening distance, in my room ~12', the JBL papers show the change from NF to FF occurring at ~800 Hz for a 6' high line. If, below 800 Hz, we're left with a 6 dB falloff per distance doubled, or monopole behaviour, wouldn't that put the B&G 75 coupled with a "bass box" matched to a certain listening distance right in line with what a full 6' line array would do?

Pete

[JonMarsh]

That's true up to a point as a theoretical calculation - but the affect in drop off transistions over a wide region, not all at once. Also, there are other benefits to the line source that I've noticed even down to the 150 Hz region in the behavior in room between a point source woofer up to 400-500 Hz and a system that's acting as a tall line source. A classic example (that I'm very familiar with) would be my X1 Klones.





In the region from about 125 to 250, they act as a five to six foot tall line source. They are vastly less sensitive to floor bounce, ceiling interaction, and modal modification than any single driver setup I've tried in the same rooms, and I can only attribute this to the benefits of the operating somewhat as a line source in this frequency range. In practical room sizes with an "impractical" six foot driver array, these benefits seem to hold over a fairly good sized listening range.

But you know, this isn't religion, this is home audio, and as I stated earlier, if Hank or anyone else needs to work within different esthetic constraints, they can still put together a fine system. It will just have a few extra constraints as far as optimization and overall performance goes, IMO.

As a side, for example, I'd say the Whisper Klones we did for Thomas, which are a tall dipole speaker, has a bass character that matches very well to the RD75's in definition and natrualness- I think that would be hard to match, for example, with a box speaker using a single woofer. Done lots of those, with high quality contruction, critically damped alignments, etc. You just find it much harder to reduce the room signature...


-Jon




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[PMazz]

That makes sense, thanks.

Along a similar line of thought.....

If the ctc spacing of the woofer line, assuming a 500 Hz xover, could be as much as 27" without introducing comb filtering, would this still behave as an array?

Pete

[JonMarsh]

Actually, it will. Legacy Audio uses this principle in designing the layout of the Whisper; the 15's are blended over to the 7's around 250 - 300 Hz, and the height of that array CTC is just withing those bounds- pushing it maybe, a little.

This prinicple of comb filtering and messing up the behavior holds true with regards to more common "line sources", like MTM speakers. Here, the lack of observance is most often in having a crossover frequency which is too high considering the CTC with a midrange driver placed between. Another way to rule of thumb this is the allowable spacing between any two drivers for a given crossover frequency; that's about 13,560/Fxover; so, for example, for a 1250 Hz crossover, the driver centers should be no more than 10.5 " apart.

Ideally, for an MTM array, you'd like the midwoofers no further apart either, and so it's usually better to use an arrangement like the Adire MTM or the Arvo Part which keeps the midwoofers close and moves the tweeter off to one side.

Good geometry is an important factor in a successfull speaker design; a lot of the information regarding these issues has not been so widely discussed (certainly not for DIY'ers like us) before the advent of the 'net. It certainly has upped the pace for the dissemination of information! But, perhaps, it's also raised the noise floor a bit, too, so the absolute signal to noise ratio may not be that much improved! :LOL:

Best regards,

Jon




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[PMazz]

Are you trying to tell me I'm reading too much.....or reading too much into this?

So, if one wanted to do a LA "on a budget", using the big B&G 75 and some appropriate woofs, a 6' line of maybe 4 woofers could possibly do this thing? And do it right?

Pete

[Hank]

LOL. Yoda, here I am on the floor, wading through the noise, but I'd say it's worth it to put up with lots of noise to get to the wealth of valuable info such as you and Thomas share.

When the specs for the MCM 55-2321 arrive, I'll post a comparison with the GR165 specs.

PMazz, If you call a B-G RD75 "budget", I'd like to know what you call serious money! 8O
It appears that no matter how you slice it a narrow ribbon enclosure on top of a bass box does not work for best sound quality, per msrs. Jon and Thomas. And, spending the kind of $$ we're talking about here, I'd go with a wider enclosure to get that "best" sound we're all pursuing.

[JonMarsh]

So, if one wanted to do a LA "on a budget", using the big B&G 75 and some appropriate woofs, a 6' line of maybe 4 woofers could possibly do this thing? And do it right?

Short answer: Yup.

Main concern is adequate swept area and volume capability (which DPL12's should do OK, for example) and staying below the first cone modes of the DPL 12 or other woofer driver.

Even the Titanic 10/(11)'s might be OK; one should recognize that the dipole LF output (below 50 Hz or so) for each side would only be equivalent to what a single sealed 11" could do with an 16 mm Xmax. That's still fairly substantial (110 dB max @ 35 Hz per side), considering you have two (stereo), which gives you another 3 dB. If 113 dB doesn't make you happy on the top end, then add an AS-15 or two, or a big IB sub.



Then, there's folks like ThomasW who can cross in an IB sub at their leisure... which makes the system configuration and output a little easier to manage still.



Regards,

Jon




Earth First!
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We'll screw up the other planets later....

[PMazz]

Hank,
Oh, this is really all wishful thinking at this point! I will give it a go one of these days and it's nice to dream of the possibilities, as well as work out some of the details with folks like Jon and Tom.

I still haven't finished my current project yet! Hell, I've got over $600 into those at this point! After that, maybe a foray into dipole speakers with Jon's Arvo's, and then maybe.....

Maybe by some twist of fate I'll find a deal on the B&Gs and just have to pick them up. Hey, maybe we can get a group buy going?

I think what I really need to do is sell some of the speakers I have laying around. I hear that the used DIY speaker market isn't too hot, tho.

Pete

[Hank]

PMazz, if you find a "deal" and there are more than two, let me know. Now "group buy" has a nice ring to it. Might be a problem finding enough other buyers. Which forums allow posting for interest in a group buy? Probably all except HTF, eh?

[Lex]

This thread is like a freekin Timex, it just keeps going and going. Next thing you know, they will call it TTP, lol. :LOL:

Lex

[JonMarsh]

Yeah, Lex,

This is the DIY Dipole TTP thread... it's like the little battery bunnies.... never seems to run down! :LOL: Whatsa matter, is it sucking bandwidth from the real TTP thread?

You should hear what some BG ribbons will do properly setup in the midrange... there's a lot of good reason for the interest.

Now if I can just talk Thomas into setting up a full X pattern surround system with four matched BG based dipoles, I bet we have a chance at going one up on the WideScreen Review Sonic Holography setup with their big Dunlavy boxes....

I think something like that would make folks quit worrying about whether their surround process it DPL Pro or 6.1 or 7.1 or whatever...


Regards,

Jon




Earth First!
_______________________________
We'll screw up the other planets later....

[PMazz]

Heh-heh, if Jon can talk a few people into a surround setup with these, we won't have to worry about finding folks for a group buy.

Hey Lex, seeing as how PE is a sponser, maybe you can talk them into good pricing, seeing as how they're getting all this commotion about their product. I'll be more than happy to be a guinea pig if they should decide to donate some "for the cause". :hb

Pete

[Lex]

If it's a product on PE's site, I am sure they would work with me on a group buy. Well, more than likely anyway. To be honest? Something like that is just what the Dr ordered really. Showing we believe in our sponsor's product. You guys work it up, I will go to bat.

Yeah, the energizer bunny goes better with what I said jon than a timex, doh well, you get the point. haha, sucking bandwidth from the real TTP. :LOL:

Lex

[Hank]

Pete, I tried 3 times to send my reply to your e-mail, so here I am. If wholesale is 515, the the RD40 would be about $334, right? I've noticed that Home Theater Spot seems to do lots of group buys.

Why are you guys pushing for the RD75? This reminds me of the good old days of "my V8 has more horsepower than yours". Will we males never change?
Seriously, since critical listening is normally done in a sitting position, why wouldn't the RD 40 work perfectly well? Look at the cost difference. And if you extrapolate to Jon's dream of an "X" with an RD-based tower in each corner, you're talking some real money!!! 8O Was it Henry Kissinger who said: "A billion dollars here, a billion dollars there, pretty soon you're talking about some real money."?

Jon, what does TTP stand for? I'm new here.

[JonMarsh]

Good morning everyone in the Dipole TTP thread! :LOL:

TTP is the "chat" thread located in the "Not Ready for PrimeTime" forum section. Go on over and introduce your self and say hi to the guys and gals. I'm so stressed for time I stay out of there or I'd never get any work done.


Yup, that ThomasW character is just another one of those Rocky Mountain Coast Elitest Snobs with his high falutin RD75 drivers. He bought those a little while back, and got a pretty nice price on them at the time. Also, though at that time it didn't occur to him to try them with the 'stats (sometimes it takes an engineer to suggest the obvious....), the plans he/we had were for something resembling a Swan Dul 'Cet klone, and that required the BIG ribbon, not one of the itsy bitsy teeny weeney ones...

Then, there is the factor that the line array behavior and vertical dispersion control is maintained to lower frequencies by a bigger line... so there are some benefits to "Mine is bigger than yours..." other than DIY bragging rights.

Still, there's no doubt that something nice can be put together with the RD50 or RD40- as I mentioned earlier, there's an Arvo Part MkIII configuration on the drawing board with the RD-40. But it's a bit of a monster, too, because it will have to be about 68" tall (5'8") anyway, but the ribbon won't extend to the floor, only down to about 2' off the floor- so no lying on the carpet to listen to tunes, unless you've got your head propped WAYYYYY up.

This configuration will probably use an 800 Hz crossover, wtih 4 M8a drivers in a "baby" mid-bass/midrange line array, with dual DPL12's on the botttom. Or I may scrap that whole idea (depending on how Mk1 and Mk11 AP work) and just do an RD50 with 4 Titanic MkII woofers. That would be about 55" tall overall. Then I would have to crossover about 400 Hz - 450 Hz, with my super dooper driver peak pooper crossover (cauer-elliptical). (Let's face it, no one's going to ever hire me to write copy for high end audio- I just can't force my self to take it too seriously. That probably comes from not having to try to make a living from it.

Regards,

Johann




Earth First!
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We'll screw up the other planets later....

[Lex]

This would be the JTP thread. Jon and Thomas Page.

Lex

[Hank]

"TTP is the "chat" thread located in the "Not Ready for PrimeTime" forum section. Go on over and introduce your self and say hi to the guys and gals."

Thanks, but better not. I spend too much time on HTF, HTT and now thanks to the dynamic duo, THIS forum!

"Then, there is the factor that the line array behavior and vertical dispersion control is maintained to lower frequencies by a bigger line... so there are some benefits to "Mine is bigger than yours..." other than DIY bragging rights."

I should have learned by now. In the future, whatever the project, this should be the conversation: J&T, what is the MOST expensive driver implementation I could do for my Belchfire IIi speaker project? You'd then come back with the some of the most, if not THE most expensive drivers list, plus crossover component list, including the new high-end film caps wound with an insulator made with the foreskin of Tibetan yaks for ulitmate grit-free soundstage presentation. Then, I'd make my kid go get another student loan and I'd buy the stuff. Simple - no hassle, saves my time, J&T's time, Lex's file server memory space, everybody's happy

"Or I may scrap that whole idea (depending on how Mk1 and Mk11 AP work) and just do an RD50 with 4 Titanic MkII woofers. That would be about 55" tall overall. Then I would have to crossover about 400 Hz - 450 Hz, with my super dooper driver peak pooper crossover (cauer-elliptical). (Let's face it, no one's going to ever hire me to write copy for high end audio- I just can't force my self to take it too seriously. That probably comes from not having to try to make a living from it. "

Glad you've found the best way to poop driver peaks. And yes, you wouldn't make it writing ad copy for high-end audio, which requres snake-oil hyperbole replete with non-related nouns and piercing adjectives.

Time to get down to the nut-cuttin'. Are we going to pursue a "group" buy of RD's? How about going for a percentage that could be applied to either the RD 40, 50 or 75? Is this Lex person the man with the connections? Would it be poor taste to approach B-G instead of PE since PE is an advertiser? Pete, where are you? Should we post an interest inquiry on other forums? Obviously I'm a group-buy virgin.

What a fun thread!

[PMazz]

Sorry Hank,
I just did a double DOH! I realized that I never updated my new E-mail addy and immediately went into my profile to change it. Well, after that I typed up my first reply, and was told I wasn't logged in and lost it all.

So....let me try to remember.

As Jon said, the shorter B&Gs will not cut it for a line array unless they're crossed over pretty high. And you'd still have to have a tall midwoofer line next to them anyway. So, it looks like I'm stuck with having to get the RD75s. It's quite a leap of faith to put out that kind of money for something I've never listened to before, but with Tom and Jon's recommendation, it's quite a bit easier to swallow.

As far as Tibetan yak foreskin, there's a group buy going on over at the Dali Lhamas site. For a cheaper alternative try : www.sorepeckers.com, although I'm not sure of the quality.

Pete "I'm still a virgin, too" Mazz

[Hank]

"As Jon said, the shorter B&Gs will not cut it for a line array unless they're crossed over pretty high. And you'd still have to have a tall midwoofer line next to them anyway. So, it looks like I'm stuck with having to get the RD75s. It's quite a leap of faith to put out that kind of money for something I've never listened to before, but with Tom and Jon's recommendation, it's quite a bit easier to swallow."


Why? Why? Always I ask why? In above posts, I got the impression that shorter than th 75's is okay and does NOT compromise sound quality. Has my wishful thinking colored my perception? Maybe I should order the foreskin film caps now. sigh :cry:

Group buy...group buy

[PMazz]

I'm sure Jon can answer better than I, but I'll paraphrase the JBL papers, as I have no real world experience with LAs.

One of the benefits of a LA is that, as listening distance doubles, the sound from an array will only drop off 3 dB (nearfield), vs 6 dB (farfield) of a single source. This holds true based on the ht of the array vs freq. For higher freqs, an array can be shorter and still behave in the nearfield (3 dB drop off). With a listening distance of say ten feet, the near field to far field transition for a 4' line is ~1kHz. So anything below 1kHz will be dropping off at 6 dB vs everything above still staying at 3 dB. That is what Jon was talking about when he said the tall B&G with a bass box could only be "tuned" to a certain listening distance. To cover freqs down to around 500 Hz where the xover to the B&G would be, the line must be at least 6' long to keep the listener in the nearfield.

I hope I made sense and didn't butcher the theory too much.

Here is a link to some good info from Jim Griffin on the Linus Array.

http://www.prism.gatech.edu/~gte929u/LinusWP.pdf

Pete

[JonMarsh]

Hey Hank,

Just pick yourself up a cheap ticket from Austin to Denver, and drop into Tom's to hear them!

It's too bad Jet Blue doesn't fly that route, because they've got some amazing fares these days...

I'm going to be in Austin later this month on business, but unfortunately I won't be stopping back in Denver on the way back- at least, that's not in the plan for now.

All of life's a gamble...


-Jon




Earth First!
_______________________________
We'll screw up the other planets later....

[Lex]

Dang, I missed the flip! :LOL:

Lex

[ThomasW]

Yup the TTP guys are going to be jealous

Pete and Hank, the both of you have access to probably the best pricing available for the RD planars. I doubt that PE would make a offer better than the current 4+ commercial account pricing.




theAudioWorx
Klone-Audio

[Hank]

That is what Jon was talking about when he said the tall B&G with a bass box could only be "tuned" to a certain listening distance. To cover freqs down to around 500 Hz where the xover to the B&G would be, the line must be at least 6' long to keep the listener in the nearfield.

I don't think Jon was referring to the length (height) of the ribbon stack, or RD model, if you will. He said that a ribbon stack or RD, on top of a conventional bass box could only be tuned to a certain listening distance because the bass box is conventional, and IT doesn't behave as a line source, but a point source. It's not the ribbon height, but the fact that the bass box I asked about is not a line source.
Am I missing something else?
I printed and read the Jim Griffin white paper. Interesting info on power tapering.

BTW, Thomas is probably correct about B-G lowest pricing. E-mail me if you don't understand

[PMazz]

Yea Hank, that's what I was trying to confer.

If you look at Fig. 1 in the white paper, the NF/FF transition distance chart, and find your sitting distance, you'll see that a 3-4' line will only behave in the NF down to certain freqs. The RDs will play down to ~500 Hz, and that's why we need to use the tall 75s to maintain NF decay rates at the listening position.

I didn't think pricing would get much better, but it never hurts to dream.

Pete

[JonMarsh]

Even though theory predicts that a 6' line source won't behave all that much like a line source below 400-500 Hz, believe you me, it couples into the room and projects a much more consistent mid-bass to low midrange response than a single driver box would. The line source behavior doesn't just "turn-off" at a specific frequency, it's more like it attenuates over a range.

Having a tall launch platform in the upper bass through low midrange greatly reduces things like floor bounce comb filtering, suich as Roy Allison describes for non-boundary loaded drivers.

There's only one way, of course, to really appreciate these phenomina, and that's to build it and see.

Everything's relative, but as Thomas points out, a set of RD-75's at PE's commerical pricing really isn't that bad a deal. Contrast that with the raw driver cost to build a set of X1 klones, for example- which is $600 plus for just the midwoofers, $160 for the tweeters, and almost $2000 for the woofers. (Now, that's not cheap, either, but it's a bargain compared with buying one of the big Wilson speakers....)

If you put this into the context that this isn't something you're going to outgrow for 10 years or more (think about how long Thomas has had his Acoustat panels and is still using them quite happily- through some tweaks and upgrades, perhaps, but still amortized annually, a very cost effective investment), then I think the cost is quite reasonable.

Especially when contrasted with a lot of the Audiophool upgrade of the year process- new speakers every two or three years, and half the changes being more in the way of lateral moves- different, but really aruguably better? What 2-4K buys you at retail these days just isn't all that special in most cases.... I have a my own little bookshelf project, which for $600 in basic materials compares very well with many systems in that range, even up to $5K. Just ask Thomas, and he hasn't even heard the MkIV yet....





-Johann




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We'll screw up the other planets later....

[Hank]

Well, I've journeyed from NEO 8's to RD-40's to one mention of RD-50's (Jon's possible experiment with an RD-50 and some Titanic II 10"/11" ers) and leapt to the RD-75's. Actually, I think my journey is being "led" by my intrepid dynamic duo mentors.
Okay, one last reality check here. Will the sonic benefits of an RD-75 over an RD-50 be worth the money and the extra height of the system? I assume more woofs with the RD-75 than with the RD-50? Again, I'm talking monopole ribbon and ported (rear) woofs. (As if I didn't know the answer :roll I promise to never ask again.
So, if its' an RD ribbon, then you recommend a stack of Titanic 10"/11" drivers alongside an RD-75 vs how many alongside an RD-50? I understand the extra expense of going with the Titanics is more than offset by not needing to do a dipole box with the Adire 12" DP's as you would if you used a stack of the 8" M8a's.
So, RD ribbon alongside a stack of X Titanics. Get me down flat to 60 Hz where I can cross to my Tempest sonosub and I'll be in business. Do I have a plan?

Nice looking monitor, herr doktor Johann

[PMazz]

Hank,
If you don't do a dipole, you can probably get away with some less expensive 6-8" drivers. You shouldn't need much excursion if you use 6-8 of em. And we're only talking about reproducing <500 Hz anyway, so the more expensive stuff is probably unneccessary. This would help keep the baffle width down, also.

Pete

[Jack Gilvey]

Pete, I'll be over as soon as you finish these up. I'll bring beer.

[PMazz]

Jack, bring a few more beers and we can put together one or two of those Labhorns as well!

Pete

[Jack Gilvey]

I'll tell you, Pete, if I did try to tackle one of those, I'd definitely enlist your help. That's one box I could royally screw up... even sober.

[ThomasW]

Hank

The fundamental benefits to the taller planars is higher output. higher power handling, less floor/ceiling interaction. Their drawback is $$$$ and size of the speaker.

Jon hasn't assembled the Arvo's yet so we only have abstract data about the performance of the 10" Titanic.

The primary reason the 10" Titanic was chosen is that it's top end rolloff characteristics are such that no dipole EQ would be needed in the original Arvo P. design. Also the Titanic was chosen to be used as a dipole. There's no reason to go to the added expense of the Titanics if you plan to have a ported midwoofer array.

As you correctly conclude the woofer/mid woofer stack should be as tall as the chosen planar.....The choice of which woofer/midwoofer is dependant on the XO point.

A sealed/ported stack of M8a's mated with any size larger B&G planar would be a astounding system.

If you want to save some money I'll make you a very attractive deal on the Eton 8-480 Hexcone Kevlars I was going to use for the Dul cet' klones. I have 16pcs. 8 were mounted in the test baffle and run for about 2hrs with test tones. The other 8 are in factory sealed boxes. These drivers have a somewhat short Xmax so I recommend using 8/side with a RD-75

BTW, I spoke with PE today. Currently they're out of stock on both M8a's and RD-75's




theAudioWorx
Klone-Audio

[Hank]

Thomas,
I can't find a listing/specs on that Eton. I even checked the Eton web site and it lists only two 8"-ers: 8-472/32 and 8-800/37. Very expensive, BTW!

I'm thinking about a combo of an RD-50 and six 6 1/2"-ers. Or an RD-75 and eight 6 1/2"-ers per side - IF I have to. What do you guys think? I want a big dynamic range for realistic large ensemble reproduction.
I'm still waiting for that excellent MCM customer service to get the
55-321 spec sheet in the mail that I asked for over a week ago.
I may give up on it and seriously consider Danny's M16 or GR165.
Once that decision is made, I'll be ready to place an order.
Pete, what time frame are you thinking about ordering B-G's?

[Lex]

Will the sonic benefits of an RD-75 over an RD-50

Hank, what about an RD-80, 90, or even 100? Should you upgrade again? LOL JK.

Lex

[ThomasW]

Hank

Jon addressed the 6.5" vs 8" issue elsewhere in this thread. We both recommend using 8" drivers.

The Eton 8-480/32 are a long discontinued driver that's why you can't locate the T/S parameters. Here they are from the BassBox Pro data base. The low Xmax (actually it's slightly higher than what's listed below) isn't a issue IF the drivers are used in a line array



The driver are very smooth....

Nearfield measurments


2 meter meaurements



The original cost of the Eton's was well over $100ea, I bought them as as closeout for $68ea and will sell them for $.....(email me)




theAudioWorx
Klone-Audio

[Hank]

aLex: Funny, verrrry funny. I hope T&J don't read your post. :evil:
I can just hear it now: "Say, you know what, Hank? Lex has a point. For ultimate soundstage presentation and absolutely zero floor/ceiling bounce, I recommend you get a 100." OR: "Say Hank, B-G is coming out with an RD-130 next year. Why don't you go ahead and build a cone driver-based line source to tide you over? There's a great 10 11/16" EtDynFocVi driver that's made with the sun-dried butt skin of water buffalo that has zero cone modes. They're only $196.23 each and a stack of 7 per side will knock your socks off." 8O

[Hank]

Thomas: Sorry, I was hanging on to my goal of narrowest possible baffle width. ops: I'll send you an e-mail regarding the Etons. Looks like I'm a bit closer. It's down to which RD. I surmise there will be an SPL difference, but how much? I note that the RD-50 nominal impedance and Re are 4 ohms and the RD75 are 6 ohms. I'll have two channels of Acurus power amp at 200-watts per.

[ThomasW]

Actually Wisdom Audio (Tom Bohlender's separate company) make the Wisdom Infinite Grand ($600.000.00/pr) They use a double height stacked custom version of the RD-75 so basically a RD-150!

Hank

I realize that people are seeing either the Linus arrays or the GR-Research one with straight sides. That baffle design is fundamentally flawed. The straight sided baffle will only reinforce the output of the woofers at one frequency. That's not a good thing.

Regardless of the woofer chosen the baffle can't be narrow. It must be a trapazoidal shape for best performance




theAudioWorx
Klone-Audio

[Hank]

$600,000?! 8O

Trapezoidal? You mean the baffle can't be flat? Or do you mean the cabinet sides can't be at right angles to the baffle?

Mama never said life would be simple...

[ThomasW]

Yup $600.000.00

Trapazoid






theAudioWorx
Klone-Audio