proaudio dipole, tips/design?

**Dennis H** · 18 April 2007, 17:46 Wednesday

The new 8" BMS coax looks pretty tasty on paper. I don't know anyone who has used it though. Looks like it uses the same tweeter driver you picked with a recommended 1.9K XO. The woofer (midrange) Le is very low and the impedance curve is pretty flat and smooth, implying a low distortion motor and no serious cone breakups.

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http://www.bmspro.info/photos/bmspro_info/8CN252.pdf

**joecarrow** · 18 April 2007, 17:56 Wednesday

I think you'll really like the sound of paper pro drivers for that type of rock. It's true that the paper pro drivers have a little bit of extra distortion, but it's fairly euphonic for that style of music. It adds a nice bite, and seems to give it a more aggressive sound- and I really like that. The guitar solos and hard rock drums really seemed that much more dramatic and "in your face" when I had an Eminence Beta-8 as my main midwoofer.

If you're going dipole, an 8" paper cone woofer with the waveguide tweeter would be a reasonably good match. The efficiency of a pro mid will really help you get those high SPLs without breaking the bank on multiple channels of large amps.

For dipole bass, displacement starts to matter far more than efficiency. The RSS390HFs should be able to cross high enough to be really useful for a mid with more limited excursion than the Seas driver in the Orion. Since you already have them, I really don't think you can do much better than just using them.

With a high crossover point between mid and woofer, it looks like the shallower H or C frame the better. If you make it too deep, you'll get the cavity resonances that limited Linkwitz from raising that crossover point higher on the Orion. Granted, the Peerless XLS driver wasn't clean much higher anyway so it wasn't really a compromise, but in your case it would be worth looking into.

Again, I wouldn't worry too much about a little midrange distortion in your system. I think that these bands sound kind of thin and lifeless if the playback is too clean.

**thadman** · 18 April 2007, 18:15 Wednesday

What kind of baffle design would I go for the H-frame? What sort of dimensions would I be looking at to put the resonance past my crossover point? Can the RSS390HF handle that high of a crossover (300/400hz?) Would they operate as cleanly up high as the Ciare? How heavy would the baffle need to be to resist rocking?

**Dennis H** · 18 April 2007, 18:17 Wednesday

I did a little more surfing on the BMS coax. This appears to be the 8" mid it's based on and it includes distortion curves. The distortion is pretty impressive IMO. At a glance, it looks bad -- up to 5% 2nd harmonic from 300-4K with much lower 3rd. But then you look at the SPL it's being measured at -- over 115dB -- YIKES! Most 'hi-fi' drivers would just puke and/or melt at that kind of SPL. Seas measures (or used to when they published the curves) at 96dB and Adire measured (when they were in business) at 90dB. 115+ dB is 100x the power as the Seas test. Holy Crap!

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**thadman** · 18 April 2007, 18:24 Wednesday

How much does this driver cost? Where would I go about purchasing it? On paper does it objectively outperform those 18sounds units (10NdA520?)? The idea of being a guinea pig is quite disconcerting, even if the driver in question measures well objectively

For the midbass/bass driver, would you recommend a U or H frame?

**Dennis H** · 18 April 2007, 18:27 Wednesday

I'd do like Jon on the Isiris. Ciare on a wide flat baffle to avoid H/U resonances and cross to a sub where the Ciare poops out, maybe somewhere in the 40-60 Hz range. Even SL is running his Orions fulltime with the sub now so he's not getting much range out of his dipole woofers, just 50-120 Hz.

**thadman** · 18 April 2007, 18:34 Wednesday

I didnt expect much on the extreme low-end from the Ciare. How wide of a baffle is he using? What kind of distortion performance could I expect from this driver? Where is he crossing his?

A pair of those new Mach5 18s look tasty, I was on vacation and missed the pre-order :M Anyone have a pre-order pair theyre no longer interested in and wish to transfer the pre-order to me (paypal)? Could they fit in a reasonably large box if ported?

I would like much more input on the midrange and all the other various solutions available. How large of a midrange should I shoot for? Does the lack of power compression outweigh the beaming benefits, higher breakup, etc of smaller midranges?

**Dennis H** · 18 April 2007, 18:34 Wednesday

Assistance Audio is the North American BMS distributor and they can order anything. I hear you about being a guinea pig. I'm kinda excited about that driver but I can't really recommend it without hearing it.

Back to basics, do you have measurement gear and know how to use it? That's a first project if you're doing speakers from scratch, even (or especially) if you are using a digital XO. The time and money spent learning to take accurate measurements will be small change compared to the time and money spent trying to get good sound without them. Without measurement gear, you'll get much better results from a proven design.

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**thadman** · 18 April 2007, 18:37 Wednesday

I do not have measurement gear, but do plan on purchasing some. What would you specifically recommend?

**thadman** · 19 April 2007, 07:15 Thursday

Would Digital Room Correction (implemented correctly) yield the same benefits of a dipole setup (ie lack of bloated, boomy bass and no medley of room nodes?)

Point being is I could port the Ciare to relieve displacement demands and use DRC to gain the positive effects of dipole radiation in the midbass/bass.

**ThomasW** · 19 April 2007, 11:02 Thursday

Originally posted by thadman

I do not have measurement gear, but do plan on purchasing some. What would you specifically recommend?

Projects update and iformation page

https://web.archive.org/web/20080726115702/http://home.comcast.net/~thomasw-2/SubwooferSetupandEQpage10.html

**joecarrow** · 19 April 2007, 14:10 Thursday

Originally posted by thadman

Would Digital Room Correction (implemented correctly) yield the same benefits of a dipole setup (ie lack of bloated, boomy bass and no medley of room nodes?)

Point being is I could port the Ciare to relieve displacement demands and use DRC to gain the positive effects of dipole radiation in the midbass/bass.

Only to a point, in certain rooms. If you read Linkwitz's comments on the Beolab 5, it's clear that he recognizes that method as viable. I personally heard some Beolab 5s, which use a sealed 15 with extensive equalization and room correction, and they had some of the most neutral bass I've ever heard. I'll agree with anyone who wants to say that the mids and highs are more "They're here" than "You're there", but the bass was just bass.

The problem is that room nodes can easily be 15 db in magnitude- do you have that much headroom in your woofer and amplifier? Will the excess distortion from having to drive 15 db harder at certain frequencies be audible? Although you definitely can see improvements from digital room correction (most folks around here use parametric equalizers with their subwoofers), you've got to have the headroom to pull it off.

The Ciare looks like it's going to take some EQ just to get flat to 30 hz. If you had a null anywhere below 60 hz, I don't think you'd be able to fill it in very well. I'm not saying dipole is better, just saying that DRC is no magic bullet.

**thadman** · 20 April 2007, 16:37 Friday

Would you compare the DRCs bass to the best bass dipole has to offer? Can they have a significant positive effect on the midrange (>300hz)? How difficult is it to get one of those setups up and running?

I could probably port the Ciare and use it as a dedicated midbass/lower midrange driver and cross it at 60hz or so to a large displacement monopole alignment for ultimate dynamics. (ie 2 of those Mach5 18s or several of the low xmax 18s, although a hefty amount of equalization would need be applied to get them down in the lower octaves with that ~30hz Fs)

I'd like to focus on the midrange at the current moment, deciding upon one seems to be giving me the most trouble. What other options beyond that BMS driver are viable? Has anybody personally listened to the PHL 1120 and compared it to other pro midranges?

**Dennis H** · 20 April 2007, 17:41 Friday

JonMarsh chose an Accuton mid to go with the BMS tweeter and Ciare woofer on an open baffle. You seem to be reinventing his Isiris. Latest version is toward the end of the thread. Any particular reason you don't want to use his mid?

**joecarrow** · 20 April 2007, 17:44 Friday

I haven't heard a good dipole setup- all of my experimentation with dipole was with cheap drivers, and without much bass content. Based on the rigor and apparent objectivity provided on a few websites describing dipoles, as well as various simulations available, I believe that good dipoles would provide extremely accurate bass.

I built ported boxes in what people would describe as either an EBS or mass loaded transmission line, and the influence of the room was extreme. With a test tone I was able to walk around the room and hear the tone loud and clear in one spot, and greatly attenuated just a foot to either side. The ports were firing almost directly into the rooms corners. The floors were hard wood, and the walls were ancient plaster. A software parametric equalizer could help some, but only at a specific location.

Dipoles can certainly employ DRC. The prevailing philosophy around here seems to be that it's best to tackle acoustic problems with acoustic solutions when you can. If you can avoid dealing with room problems by using a dipole, then it will be simpler to do that than to send an inverse signal of your room to your speakers.

**thadman** · 20 April 2007, 17:57 Friday

Originally posted by Dennis H

JonMarsh chose an Accuton mid to go with the BMS tweeter and Ciare woofer on an open baffle. You seem to be reinventing his Isiris. Latest version is toward the end of the thread. Any particular reason you don't want to use his mid?

#1 The mid costs $305/driver (EXTREMELY hard to justify)
#2 I've already got a pair of Seas Excel W18E midranges that could provide amazing midrange clarity up to 1.2-1.3khz (basically accomplish the same thing)
#3 Theyve got a mere 89.2dB sensitivity rating, compared to the 114dB or so that the BMS is rated at...I doubt these could provide the dynamics of the BMS or Ciare
#4 They're not paper cones and would probably rip my listening material (progressive rock, ie TOOL, Dream Theater) to shreds. TOOL adds a lot of distortion to their material and im not sure how favorable the extreme resolution of a midrange such as these would be...

**JoshK** · 20 April 2007, 21:29 Friday

I listen to a lot of the same music. I like low distortion speakers as neutral as can get and plenty of effortless midbass punch. Tool is my all time favorite, has been since I was in HS, half my lifetime ago.

**JonMarsh** · 21 April 2007, 07:08 Saturday

Originally posted by thadman

#1 The mid costs $305/driver (EXTREMELY hard to justify)
#2 I've already got a pair of Seas Excel W18E midranges that could provide amazing midrange clarity up to 1.2-1.3khz (basically accomplish the same thing)
#3 Theyve got a mere 89.2dB sensitivity rating, compared to the 114dB or so that the BMS is rated at...I doubt these could provide the dynamics of the BMS or Ciare
#4 They're not paper cones and would probably rip my listening material (progressive rock, ie TOOL, Dream Theater) to shreds. TOOL adds a lot of distortion to their material and im not sure how favorable the extreme resolution of a midrange such as these would be...

You're probably looking at the wrong specs on the midrange- Craig is going to use the the C173-T6-95, which has a sensitivity of 89.1 dB and a price of $275, but I'm using the C173N-T6-90, (old number was the C90-T6, which is 93 dB/watt using a neo underhung motor that's very low distortion, and unfortunately, $460 each. They have very low distortion (as far as I've measured) up to the 106 dB level. While they are certainly revealing of what ever you put into them, unlike many other drivers they won't add a fair amount more midrange distortion when you push them harder. This is particularly critical, IMO, in the 1-3 kHz area (presence range) where the human ear is most sensitive to this sort of thing.

I listen to a lot of kinds of music, including older progressive rock like the Yes, fusion jazz like Al Dimeola, and a variety of blues and zydeco which can be pretty in your face. I think you want your drivers to add as little of their own editorializing as possible. Do you like your favorite recordings played on really clean wideband headphones? If so, you'll probably like them with this sort of higher efficiency but low distortion approach to a dipole.

I spent some time looking at "pro" cone midranges, too, and some parts like the 6ND430 were intriguing, but it didn't have an efficiency advantage over the Accuton's- to the contrary, it can't match the C90-T6, (it's rated at 92.5 dB, but that's only achieved from 1 kHz and up; in the 200-400 Hz region, it's about 89-90). But it looks very easy to work with, if the SPL plots are accurate. And it does have an Xmax of about 5 mm.

OTOH, if you have the W18's, you might be able to pull off a match to the BMS4540 depending on the waveguide you use, but you'll be getting very close to the HOM mode on most at the bottom end. I think the BMS4540 and most available waveguides work best from about 1600 to 1700 Hz and above, and that's too high for the W18. It starts to get into some serious energy storage issues above 1200-1400 Hz; 1400 is as high as I would recommend taking that driver.

Whichever midrange tweeter combo's you end up selecting, it might be interesting to do some CSD plots before chosing the final crossover frequencies.

Just some thoughts....

~jon

**thadman** · 21 April 2007, 09:51 Saturday

That midrange looks amazing...WOW $460/each + s/h 8O though...I could buy nearly 40 RS180s over on partsexpress with a volume discount for that price. There is NO way I can justify that, not even close. The 10NdA520 was nearing a stretch for me at $225/each...thats more than the Revelators :x

How would 2 PR170M0s/side fair distortion wise? They appear to be quasi-PHL 1120s with less xmax and would only cost $160/side for 2.

**Paul W** · 21 April 2007, 10:17 Saturday

If you're looking at 10 inch 18sound drivers, with your crossover frequencies, I'd be more inclined to go with the 10NDA610. I used the 10NDA520 but XO at 200 and 1-1.5k. The 610 is more of a pure mid and seems better suited to a little higher range.

If you use a modular approach (interchangeable woofer, mid, tweet building blocks) I think you're good to go with what you have. The W18 will be a stretch on the top end but, with care on the breakup, it can work. By the time you hone your crossover skills, you can easily save up for the T6-90's Jon is using.

**thadman** · 21 April 2007, 12:54 Saturday

I received the W18Es in a trade (theyre still brand new in their boxes) and would much rather sell them and buy a more dedicated midrange vs midwoofer.

This project is just to wet my feet, and may or may not be permanent (depending on how it performs). I doubt I'd notice a massive improvement (enough to justify the investment) on the accuton midrange, so I'm looking for an alternative.

Modular design? hmmm...how would that affect refraction and the like? It doesnt sound very desirable in terms of sound quality.

How are you liking your 18sound driver? How is it in terms of clarity, distortion, dynamics, etc? and subjectively can you compare it to any other driver you've used or prefer it to any others? I've read several of the threads you've posted in, but have never gotten any subjective information concerning your midrange.

**Paul W** · 21 April 2007, 17:47 Saturday

Modular design? hmmm...how would that affect refraction and the like?

That depends entirely on the implementation.

Haven't gotten serious with the 520's yet. For now, all of my spare time is spent on waveguides. The only A-B comparisons (holding BMS woofer and tweeter constant) have been with an obsolete Seas 10" poly. EQ'd to the same FR, the 520's make the Seas sound downright muffled...but the old Seas is a long way from SOTA, so not a reasonable comparison. Dynamics in spades. A quick spot check showed about a 10db reduction in HD with the AIC connected.

**thadman** · 22 April 2007, 22:07 Sunday

Assuming I opted to go with the RSS390HFs and mounted them (top: cone facing, bottom: magnet facing) how high would I be able to take them? The problem with the heavy cone vibrating the baffle can be ameliorated significantly by mounting them opposing each other, in theory canceling the individual forces of each driver. After observing the partsexpress graphs, it looks like there is a nasty 10dB peak at 1600hz and a slight rising peak 2-3dB at 1200-1300hz. From discerning the data, I can conclude that a 400hz crossover would probably be optimal, but how much lower (or even at all) should I cross them with them mounted opposing each other?

What are your thoughts on a modular baffle? How have you engineered yours to combat the problems afflicted by a modular design?

**joecarrow** · 22 April 2007, 22:13 Sunday

The only way to mount them opposing each other, that I can think of, is in a W-frame. This introduces a major cavity resonance at an even lower frequency than an H-frame. Opposing each other, I think you'd have a hard time getting them even up to 200 hz. On a flat baffle, I see no problem (based on Monte Kay's measurements) taking them up to 400 hz.

**Paul W** · 23 April 2007, 09:35 Monday

I agree with Joe on the opposing woofers. My guess is a little over 100Hz or whatever SL does with Orion.

What problems are you assuming with a modular approach? If you take whatever box or baffle design and slice it into three pieces you have three modules. If you want to do 6" roundovers, you can do it...modular or not. Modular is just an option, it's up to you if you decide to build completely new baffles every time you change one driver.

**thadman** · 23 April 2007, 23:49 Monday

I dont want to totally discount the possibility for DRC or a PC XO. The high amplitude nodes that my speakers would have to control would probably be similar to the demands of dipole displacement, but with one main advantage going to the DRC setup. I would be able to play my woofers below the room fundamental in a DRC setup. I can afford the sacrifice in dynamics for fidelity

Anyways, how much do one of these setups run including the specialized soundcard? I figure Ill probably spend $600 or so on a set of DCX2496 + DEQ2496 active processors, and the PC would allow for much more flexibility. How much more $$$ in comparison to what I would originally be spending.
Also, I've got a home brewed Pentium IV 2.8Ghz w/ 512mb ram that may serve as the processor (or is it underpowered?)

Can inefficient "HiFi" drivers (~83-88dB) be as dynamics/effortless as pro drivers given the right amount of amplifier power? Im purchasing (4) Crown XLS-602Ds off of ebay and already have a XLS-402B in my possesion, which should yield 300w@8/channel (200 watts at 8ohms for the XLS-402).

Would a woodhorn be a good option for the BMS 4540ND? I have access to a wood lathe and industrial milling equipment (would have to pay for CAD programming), so one would be feasible if the benefits over a MCM waveguide outweigh the cost disadvantage.

**Tommythecat** · 24 April 2007, 12:25 Tuesday

Can small cone and dome drivers be as dynamic? - no. Just starting at the fact that they cannot produce the same amount of output nor can they take the same amount of power. A dome tweeter will scream its last breath over 100W - nevermind the power compression seen by a 1" coil cone midrange over 100W.

Even if you used horn->ported mid->ported midbass with subs, 300W a driver is overkill using pro drivers.

When people still go on about how "power is cheap" I kinda laugh...we don't have to worry about spending all our money on tube amps because we're not in the stone age. Solid state is here, it relatively cheaper - but you cant just throw power at everything and expect good results. Power compression is becoming a reality for home users, we're switching out 5W tubes for 200W a channel receivers.

**thadman** · 24 April 2007, 20:50 Tuesday

Originally posted by thadman

I dont want to totally discount the possibility for DRC or a PC XO. The high amplitude nodes that my speakers would have to control would probably be similar to the demands of dipole displacement, but with one main advantage going to the DRC setup. I would be able to play my woofers below the room fundamental in a DRC setup. I can afford the sacrifice in dynamics for fidelity

???

Originally posted by thadman

Anyways, how much do one of these setups run including the specialized soundcard? I figure Ill probably spend $600 or so on a set of DCX2496 + DEQ2496 active processors, and the PC would allow for much more flexibility. How much more $$$ in comparison to what I would originally be spending.
Also, I've got a home brewed Pentium IV 2.8Ghz w/ 512mb ram that may serve as the processor (or is it underpowered?)

???

Originally posted by thadman

Would a woodhorn be a good option for the BMS 4540ND? I have access to a wood lathe and industrial milling equipment (would have to pay for CAD programming), so one would be feasible if the benefits over a MCM waveguide outweigh the cost disadvantage.

???

**JonMarsh** · 24 April 2007, 23:31 Tuesday

It would be a substantial investment in tooling to build a wood horn- I'd wait and see if the DDS ENG1 re-surfaces from US Speaker (currently reported temporarily out of stock, they're attempting to source/Klone elsewhere. Or you might try the larger 18sound elliptic waveguide. I'd recommend the bigger one than the XT120; harder to find. A lathe is a significant investment... just depends on how determined you are.

**thadman** · 25 April 2007, 07:10 Wednesday

Originally posted by JonMarsh

It would be a substantial investment in tooling to build a wood horn- I'd wait and see if the DDS ENG1 re-surfaces from US Speaker (currently reported temporarily out of stock, they're attempting to source/Klone elsewhere. Or you might try the larger 18sound elliptic waveguide. I'd recommend the bigger one than the XT120; harder to find. A lathe is a significant investment... just depends on how determined you are.

Are you referring to the XT1086 horn from 18sound? How detrimental are the effects of it having a slot in the mouth? Is its sound quality near the DDS ENG-1?

**Tommythecat** · 25 April 2007, 12:12 Wednesday

Quote:
Originally Posted by thadman
I dont want to totally discount the possibility for DRC or a PC XO. The high amplitude nodes that my speakers would have to control would probably be similar to the demands of dipole displacement, but with one main advantage going to the DRC setup. I would be able to play my woofers below the room fundamental in a DRC setup. I can afford the sacrifice in dynamics for fidelity

I don't really know what this is even faintly referring to.

**thadman** · 25 April 2007, 16:07 Wednesday

Originally posted by Tommythecat

Quote:
Originally Posted by thadman
I dont want to totally discount the possibility for DRC or a PC XO. The high amplitude nodes that my speakers would have to control would probably be similar to the demands of dipole displacement, but with one main advantage going to the DRC setup. I would be able to play my woofers below the room fundamental in a DRC setup. I can afford the sacrifice in dynamics for fidelity

I don't really know what this is even faintly referring to.

Im referring to Digital Room Correction. The software measures the response of your room and sends signals to the drivers to send (0 or 180) phase to cancel room nodes, accomplishing electronically the same thing as dipole (less room interaction). The system will also allow you to use any slope you want on any driver...anywhere. It also has the ability to calculate FIR filters (perfect phase response). You're really on limited on your processing power. I could use DRC on a medley of different speakers I build in the future and could use it in smaller rooms whereas dipole might not necessarily work correctly.

**Dennis H** · 25 April 2007, 17:25 Wednesday

accomplishing electronically the same thing as dipole (less room interaction).

Not even close. EQ (DRC is a subset of EQ) can only give 'perfect' response at one spot in space -- clamp your head in a vice.

If the DRC theory were valid, you could take any old speaker and EQ it and it would sound just like any other speaker. People with $$ digital gear that does FIR filters, e.g. Tact, DEQX, etc., find that is most certainly NOT the case. Speakers matter. Bigtime. As JonMarsh likes to say, acoustical solutions for acoustical problems. EQ is a bandaid best reserved for tone control or 'voicing' the system.

**thadman** · 25 April 2007, 18:13 Wednesday

Well then I guess I analyzed it incorrectly, Dipole it is then :lol:

More on the horn though. Is the assumed cost you're referring to the investment in a personal lathe? I've got a family member who owns a wood lathe (carpenter) and another who works at a company who machines and constructs specific machines for assembly lines. I will have access to a large lathe if necessary, I'd just have to have someone program it for me. In the case that the wood lathe would be inadequate, do you think the milling would cost >$150 for simple CAD programming? Once the programming was complete I could probably make several more copies

If you guys were interested and came up with a really nice design (equivalent to the DDS ENG-1), I dont see why I couldnt make them available for the rest of the forum assuming you were interested :B

**joecarrow** · 25 April 2007, 18:59 Wednesday

That much material removal won't come cheaply on a mill; it might help that we're talking about wood since I'm used to thinking about metal and plastic. It's a lot of machine time, and it is potentially a lot of operator supervision because you might not be able to count on a steady stream of coolant for chip evacuation. Overall, I think that the machine time for one wood horn that will play reasonably low would be well over $200.

I don't think it would cost over $200 for programming, supposing you were able to get the machine time for free. If the lathe is large enough, that seems like a much faster and more economical approach.

**thadman** · 25 April 2007, 19:23 Wednesday

If I was to pursue this further, what design would I use? Are there designs already available? Hornresp isnt very intuitive.

How would I build a modular open baffle? Itd be very difficult to stack the pieces on top of each other with only a 1-2" baffle to sit on (especially horn on top of midrange). If I built some sort of wings on the side, wouldnt it behave like a U frame and create a nasty resonance?

**joecarrow** · 25 April 2007, 20:04 Wednesday

I can't advise on horn/waveguide designs, but for something modular, I'd think that something along the lines of rack-mount equipment would be the way to go. Just mount everything on two sturdy uprights, and you can use whatever bolts or screws that you want. A steel or aluminum extrusion could provide all of the strength that you'd want, with a minimum of depth for reduced cavity effect. You could also line the internal edges of such a structure with foam or felt to further reduce reflections that would cause the problem.

**thadman** · 25 April 2007, 22:11 Wednesday

What should I look for in the midrange? There are sooo many to decide from. I've only become aware of a few, and that choice is hard enough (Audax PR170M0, PHL 1120, Ciare 10.64NdMr, 18Sound 6Nd410, 18Sound 10NdA520, and the 18Sound 10NdA610 come to mind). I know I shouldnt generalize (diameter determines linear performance)...so what should I look for? Should I go with something that has proven sound quality? (PR17, PHL 1120?)?

The 18Sound units look interesting, but are obscenely expensive :E Does anybody have any opinion on these? or any other definitive pro midranges?

**augerpro** · 25 April 2007, 22:30 Wednesday

I would look at P Audio also for some reasonably priced drivers thadman.

**thadman** · 26 April 2007, 15:53 Thursday

Originally posted by thadman

What should I look for in the midrange? There are sooo many to decide from. I've only become aware of a few, and that choice is hard enough (Audax PR170M0, PHL 1120, Ciare 10.64NdMr, 18Sound 6Nd410, 18Sound 10NdA520, and the 18Sound 10NdA610 come to mind). I know I shouldnt generalize (diameter determines linear performance)...so what should I look for? Should I go with something that has proven sound quality? (PR17, PHL 1120?)?

The 18Sound units look interesting, but are obscenely expensive :E Does anybody have any opinion on these? or any other definitive pro midranges?

??? Any others, how do I limit my choices? I cant test all of the drivers :cry:

**joecarrow** · 26 April 2007, 23:12 Thursday

You just need to accept that maybe you'll build the system with components that maybe aren't the very best possible. Unless you can test them all, there's no way to be sure that there's not something better out there. It's actually something that's been extremely hard for me to accept. I want to make things that are *the best*, period.

This is a matter of design philosophy, but in my experience it turns out that "Pretty Good" is a perfectly acceptable place to start. There's a jumping-off point, a time when you just need to do it and see how it goes. You've had an honest look around, and you see a few choices that look reasonable. If you're still feeling cold feet, pick the cheap one or one with good resale potential so that you can cut your losses if there's a problem.

If you get reasonably reputable drivers and use them within their recommended range, you can feel pretty confident that with moderate effort you will end up with something that sounds better than 90% of commercially available speakers. It's not like you're making an enclosure that must be the right size for the woofer, or buying components for enormous passive crossovers. With active crossovers it's cheap to change frequencies since the components are physically smaller or exist digitally.

I can tell you're putting a lot into this. Try not to get too nervous, I'm sure it's going to be great.

**thadman** · 27 April 2007, 18:51 Friday

Well, can you guys help me with some generalizations then? If this was your personal speaker that you planned on using for an extended period of time, would you go with a cheaper 6.5" midrange, like the PHL 1120 (cheaper is a relative term, $120+s/h/each isnt necessarily cheap) or a more expensive 10" midrange, such as the 10NdA610 (ie costs 2x, $240/each)? The intended bandwidth is whatever works best with the drivers (2x RSS390HF on the bottom and 1 BMS 4540ND on the top, ie ~400-2000hz).

**Dennis H** · 27 April 2007, 19:09 Friday

Thadman, we have a hard time answering your many questions because most of them have no good answer so most of us just keep quiet. We don't know any more about drivers we haven't used than you do. If you want guaranteed success, use a proven design with a published XO and bill of materials. If you want to go your own way, you're the test pilot. The old Y in DIY. Enjoy the ride and tell us how it goes. Maybe we'll all copy you.

**joecarrow** · 27 April 2007, 19:14 Friday

The RSS390HF may not be good to as high of a frequency as the 12" version. The 12" is good to 400 hz or so. With two of the 15"s, you're looking at 110 db at one meter for 50 hz, limited by excursion, so you want your midrange to be able to keep up with that at a reasonable crossover.

I don't know if it's reasonable to cross the 15" at 400 hz- but if you look here, you see that the PHL is starting to lose its edge at 400 hz:

Unconfigured Site

http://www.markk.claub.net/Testing/PHL1120/PHL1120.htm

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I've got to stop and think about this, how I would do it if it were my own. I'll try to get back to you later, after I imagine what it would be like having a larger dwelling.

proaudio dipole, tips/design?

proaudio dipole, tips/design?

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