Dipoles sorta like bob/arvo - long

**ThomasW** · 10 February 2005, 21:36 Thursday

My preliminary thought is that 5" drivers aren't going to have nearly enough output. They're just too small to work effectively in a dipole, particularily when you're using dual 15"s.

With the Arvo we're using dual 8"s to match up with dual 12"s. That should give you some idea about matching these things up.

**Paul H** · 10 February 2005, 22:09 Thursday

Thanks Thomas,

I am concerned about that - making the 15's "stretch up" or the 5's "stretch down". The 15's size may be overkill, but I figured that was a good thing for dipole bass.

Linkwitz's spl spreadsheet does indicate the same maximum spl for the 15's at 40Hz as the 5's at 140Hz, using a 20" baffle (about 107 dB). The same sheet gives me 117 dB at 200Hz for dual 5's at xmax.

Am I missing something?

Paul

**JonMarsh** · 10 February 2005, 22:11 Thursday

Are you familiar with Linkwitz's dipole worksheet? You can calculate the SPL's possible for any size driver with a given dipole panel with X front to back distance, and a given Xmax; can also calculate how many drivers you need to get down to a given LF point.

If I was going to do another new Arvo type design right now (which I hadn't been planning, but hey, twist my arm a little), I'd be looking for a driver with moderate Xmax and cone area, the highest possible first breakup mode, and Faraday rings and the lowest possible mid band distortion. A little efficiency wouldn't hurt either, as you kind of throw away a bit of that with the whole dipole thing- particularly since it usually makes sense to wire the mids in series if you're using two...

Right now, the driver which I suspect would be the winner if we held a run off, price only a moderate issue, would be the Peerless 850467 (if you only count drivers actually shipping in the US right now). It has some Faraday rings not present in the 850439, and the upper midband distortion (above 300 Hz or so) is markedly lower- though the 439 is pretty good compared with most of the competition.

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The existing mid you're looking at is pretty nice-

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The series without the phase plug don't have the Faraday rings up top on the pole piece. This one has an Xmax of about 4 mm. Sd is a little over half of the 6-1/2" HDS series. Net swept volume is under half. This is potentially a problem for a dipole, at least one to be investigated and calculated. For reference, with a 70 Hz crossover, I figured I'd need 8 Extremis on each side for the same SPL you're talking about; obviously, it depends on the chosen crossover frequency. For the Arvo, it's about 180 Hz. 15's probably won't work too well that high; the TC2+ is somewhat unique in it's stiff cone, for a 12, and relatively low VC Le- one coil is 0.845 mH, not the 2-1/2 millihenries typical for a 4 ohm sub driver.

OTOH, the new series holds the promise of possibly even better performance, especially the 830883 and the 830884. The older 8's have their first cone mode about 700 Hz- no go. The 830883 has a rising response like the 467...

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and the very low VC inductance typical of a Faraday ring.

The 884 may even be usable- in fact, I'm very interested in how it performs possibly for the Saint Saens, especially since the Extremis price has gone up, and the measured distortion in the midrange is not as low as I'd hoped...

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Other than the radiation pattern narrowing due to driver size, it may be fine to 1400 or so. But for the dipole, narrowing of the beam pattern above the panel cutoff, to match the pattern in the lower range may be just what the doctor ordered- seems to work well with the Arvo's.

Notice the difference in the inductive rise of the impedance curve? :B

Just some thoughts... are those Peerless mids the ones on sale at Madisound?

~Jon

Attached Files

850467.pdf (887.1 KB, 15 views)

**Paul H** · 10 February 2005, 22:56 Thursday

Jon,

Our posts 'crossed in the mail' - see my notes about Linkwitz's sheet above - do they make sense?

The drivers I was referring to aren't on sale, as far as I know.

I don't think the new exclusive hds series exists anywhere but the peerless website, does it?

Thanks,

Paul

PS This is a learning/training project for me, so I'm not looking for detailed design - I just want to get started in the right direction. I think you've already got a few other designs going to keep you busy in your spare time?

**JonMarsh** · 10 February 2005, 23:13 Thursday

Originally posted by Paul H

Jon,

Our posts 'crossed in the mail' - see my notes about Linkwitz's sheet above - do they make sense?

The drivers I was referring to aren't on sale, as far as I know.

I don't think the new exclusive hds series exists anywhere but the peerless website, does it?

Thanks,

Paul

PS This is a learning/training project for me, so I'm not looking for detailed design - I just want to get started in the right direction. I think you've already got a few other designs going to keep you busy in your spare time?

Oh yeah, the alligators are pretty thick in this part of the swamp!

Yes, our posts crossed in the ether some where....
:lol:

It sounds like you've got the right idea and are thinking about the right things- so I'll be interested to see how things develop. Every project is a learning project... that's why it took me 4 versions of the 8" bookshelf before the AudioXpress articla, and why I think there's may be a version 5 in the works...

Hmmm, of course, technically, the MTM versions are version 5, and the M8ta is version 6. Well, some day I'll get it right.... or closer.

**ThomasW** · 11 February 2005, 01:32 Friday

I don't think the new exclusive hds series exists anywhere but the peerless website, does it?

Solen has them

**sfdoddsy** · 11 February 2005, 04:36 Friday

My only contribution to this plethora of driver innards is the same as that of Thomas. I'd be a little worried about whether two fives can give you the sort of undostorted dynamic range that makes theese dipoles so nice.

My pair of eights may be expensive overkill, but it does feel good knowing they are there.

Steve

**Paul H** · 11 February 2005, 08:07 Friday

Thanks folks, sounds like I should be looking hard at 6 1/2's or 7's at least. The exclusive hds looks good - well actually the silver doesn't look good (imo), but the FR and TS parameters do.

Any comments on the 9500 tweeter?

Paul

**JonMarsh** · 11 February 2005, 10:03 Friday

Looks like Solen has the 8's listed for ~$79 USD, and the 7's for $74 USD, plus shipping. Now, this may not mean they actually HAVE them, but they're in the system, a good sign.

I have an inquiry in to Madisound regarding availability there.

**sfdoddsy** · 11 February 2005, 21:25 Friday

Originally posted by Paul H

Thanks folks, sounds like I should be looking hard at 6 1/2's or 7's at least. The exclusive hds looks good - well actually the silver doesn't look good (imo), but the FR and TS parameters do.

Any comments on the 9500 tweeter?

Paul

I'm obviously a fan of the Seas Millenium, but if you're looking at saving money and the 7 inch drivers cost more then the Seas 27TDF (I think that's the model) is remarkably close. I used one in my center when I blew up a Millenium and in my surrounds.

Steve

**Paul H** · 11 February 2005, 22:12 Friday

Originally posted by sfdoddsy

I'm obviously a fan of the Seas Millenium, but if you're looking at saving money and the 7 inch drivers cost more then the Seas 27TDF (I think that's the model) is remarkably close. I used one in my center when I blew up a Millenium and in my surrounds.

Steve

Steve,

The millenium was/is on my short list with the 9500 or 9700. I'm not sure the cheaper seas have the xmax/power handling I'd like.

I'm not looking to save money actually. I was initially drawn to the hds line because of value/quality, but also the fairly gentle response curves and breakup modes make them easy to work with for a relative newb like myself.

Ironically, the fact that I can identify a speaker that's easy to work with shows I've learned something in the past year.

Anyway, money is not a huge issue. I'll need to think about it before I drop an extra $500+ to go from HDS to Scanspeak or Seas higher end drivers - but all advice and suggestions are accepted. I'd hate to end up wishing in a couple of years from now that I'd spent another couple of hundred dollars.

Another idea I had and earlier rejected was to build a 3-way (still dipole) with 2-10" CSX, a 5" hds and tweeter, along with the 2-15" picking up the low end. It could probably put out great sound but might take me two years to design and build the crossovers

Paul

**Davey** · 12 February 2005, 12:07 Saturday

Paul,

Your basic objective doesn't sound too different from the speakers that I built. The basic design is nice and simple and there's no reason it can't be improved with better drivers and possibly an active crossover between mid/tweet. In fact, this is exactly what the prototypes were until I "cheapened" the design.

http://home.comcast.net/~dreite/Davey/Davey.htm

Cheers,

Davey.

**Paul H** · 12 February 2005, 13:26 Saturday

Davey,

I should have included your dipoles in the title of this thread along with 'bob' and 'arvo', as I had certainly noticed them before and thought they looked great.

At what frequencies are you crossing these over?

Paul

**Paul H** · 13 February 2005, 11:17 Sunday

I went back through my ideas and realized I made two errors in my initial assumptions.

The first is unintentionally ignoring filter rolloffs and imagining them as 'brick walls' - which is where I came up with the 5" mids getting down low enough to tie into 15's.

The second more important mistake is not looking at some higher end drivers. I'll notice spending more money now, but I'm quite certain the extra few hundred dollars won't matter in a few years. As has been noted on this forum before, if you look at the amount of time spent of designing/building speakers from scratch, and assign any value to your time at all ..

That being said, I looked through a few thousand drivers

this weekend and came up with the following drivers:

Per side:
2 - Stryke AE IB15's (already bought) low bass dipole, or IB :T

2 - Seas L26RFX/P (10'' aluminum) ~ 80 ~ 450 Hz
1 - Seas W18EX001 (6 1/2" magnesium) ~ 450 ~ 2000 Hz
1 - Scan Speak 9700 tweeter ~2000Hz and up

I realize that the woofer and mid are 'difficult beasts' to design for as both have some pretty big cone resonances - but I've got time (and LSPCad).

Linkwitz's SPL spreadsheet gives me 107 dB at 160Hz for the W18EX at 1/2 of xmax, so I could push the crossover to the 10's lower if I wanted. There's some flexibility for the crossover from mid to tweeter also, up or down.

Once I get the drivers I'll test a few configurations and try a few baffle shapes - I'm mainly interested in getting a basic concept and driver list nailed down right now.

Comments and suggestions welcomed.

Paul

**JonMarsh** · 13 February 2005, 12:00 Sunday

I think this complement of drivers is MUCH closer to what you're looking for, performance wise... Calculating to only 1/2 of nominal Xmax for dipole crossover point is also a good idea, Paul. Can you get the center's of the tweeter and W18 within 7"? If so, then it will meet my goofy wavelength criteria. The only other point to consider re your HF crossover is radiation pattern- 7's are narrowing a bit by 2 kHz. May not be an issue at all if the dipole focused radiation below that matches in directivity.

Last, something I've found works well, and you might want to experiment with before making your first test baffles, is using BDS or Edge for layout the baffle based on diffraction distribution/boundary suppot. It still seems to have a big impact on behavior; that Danish guy, Troels Gravesen, found that out with his dipole panel experiments, and I found it to be the case with the Arvo Part; a symmetrical layout like Linkwitz used for the Phoenix and Orion doesn't seem to be optimum.

Do you have any distortion meausrement capabilities? I'm going to be running tests on my RS270's in the 40-600 Hz region, and I'd be real curious to see how they stack up against the Seas W26, acknowledged to be one of the best 10's out there, probably the best.

~Jon

**Paul H** · 13 February 2005, 15:45 Sunday

Thanks Jon,

The "1/2 of xmax rule" has no technical justification at all versus say 30% or 70% - but some sort of rule of thumb like that is good. I don't want drivers at their limits, because they won't sound their best then.

The mid/tweet drivers can go as close as 5.75" centre to centre - which suggests a max of ~2400Hz to keep the driver spacing less than the wavelength of the crossover frequency. I think I'll likely keep it ~2000Hz.

Good idea on the baffle layout. I've actually used the Edge in the past, to check layout on the dual M8n's - surprise, surprise, came up with your's and Thomas's recommended spacing for that baffle :wink:

I don't have any distortion measurement capability. The extent of my current measurement setup is a behringer mic/preamp with justmls.

However, Mark K has tested the 10" aluminum seas (the L-series, not the W26). Actually I first noticed that driver on his testing web page. He's tested the RS270 in the same group - see here under "10" woofer test group 1" :

http://206.13.113.199/ncdiyaudio/mark/Testing_page.htm

The RS270 has a hitch in the impedance curve at about 750Hz, which shows up in a large hump in the frequency response, starting at 700Hz. The price is very nice, but that 'glitch' kind of scared me away from that driver - I'd be interested in your thoughts on that data.

This Seas 10" L26RFX model is $108US versus $250US for the W26. The differences seem to be that the W26 has a magnesium cone and shorting rings. The rings presumably would improve distortion, but how much I don't know. Other than that, the impedance curves, frequency response and all other parameters look identical. Where there are differences between the two on the manufacturers spec sheets they're probably less than production tolerances. I've upgraded my budget, but ya still gotta draw a line somewhere. As I need 4 of these, they're going to be aluminum, not magnesium, unless someone has compelling reasons otherwise.

Paul

**JonMarsh** · 13 February 2005, 16:06 Sunday

I'd expect the W26 to be quite a bit better, with the Excel motor and the Faraday rings, especially in the upper range, but I expected that with the Millenium Excel tweeter (which doesn't have Faraday rings, though), and that didn't quite materialize as expected. Also, I don't see the difference in inductive rise for the W26 which I'd expect with Faraday rings- maybe theyr'e just partial rings, like Seas did with their old 13 paper cone woofer.

The RS270 held it's own on the three tone test, but the L26 had a bit lower IM distortion in terms of the lower sidebands. Not sure what that would mean in practice- it's a grueling test, mot of the drivers kept the IM products better than 40 dB down for any one frequency.

My own check's and Monte Kay's tests indicate that 600 Hz is about the upper usable frequency for the RS270, which means you'd really prefer to have levels above that well attenuated.

Another thing I'm pondering is the efficiency discrency- Dayton claims 90 dB, Seas 87, but I've seen myself that the 87.5 dB rated RS180 are about 2 dB lower than the 87.5 dB rated Peerless. It's probably hard to make a valid comparison unless one measures them all by one's self.

~Jon

**capslock** · 13 February 2005, 16:11 Sunday

Actually, the W26 is the only current Excel with an Al cone. So you are paying for two rings of copper and the famous gray paint. Distortion of the W26 is definitely not on par with the W22, exept for < 100 Hz.

**Paul H** · 13 February 2005, 16:46 Sunday

Originally posted by Paul H

they're going to be aluminum, not magnesium, unless someone has compelling reasons otherwise.

Paul

Certainly not hearing any compelling reasons yet

Here's a quick sketch of a possible single panel drivers layout - just under 70" tall - should be able to get some additional boundary effect from the ceiling at that height

Paul

Attached Files

Dipole Model (1).pdf (2.0 KB, 494 views)

**Dennis H** · 13 February 2005, 19:04 Sunday

I wonder how much those big Stryke drivers will make the panels vibrate? It it's a problem, you could always do a two-piece lowboy design - WWMT and SS.

**Paul H** · 13 February 2005, 20:14 Sunday

It's possible that these could vibrate quite a bit, but I really don't know.

Thomas, if you're reading this, do you have an opinion based on real-life experience with the "flexible flyers" from a while back ?

Paul

**JonMarsh** · 13 February 2005, 20:48 Sunday

Originally posted by capslock

Actually, the W26 is the only current Excel with an Al cone. So you are paying for two rings of copper and the famous gray paint. Distortion of the W26 is definitely not on par with the W22, exept for < 100 Hz.

That's rather a shame, isn't it?

I like the tests Mark and Monte have done, but I also want to do some sine sweep and harmonic analysis- so I'm going to add that for the RS270, RS225, M8a for early March.

Thanks again for all the scans you sent me- they've been quite interesting. I'm just trying to figure out how to balanced testing and building!

BTW, do you know when the new Peerless Exclusive series will be available in Europe? I'm hearing one to three months from the distributor in the US.

~Jon

**JonMarsh** · 13 February 2005, 20:54 Sunday

Originally posted by Paul H

Certainly not hearing any compelling reasons yet

Here's a quick sketch of a possible single panel drivers layout - just under 70" tall - should be able to get some additional boundary effect from the ceiling at that height

Paul

Nice clean layout- reminds me a little of the Whisper Klones - what do you have in mind for the front panel?

This may be one of those things where you'll want to proto a few configurations until you're happy with how everything works. As low as you're crossing over from the 10's, I'd probably even consider a W cabinet with force cancellation for the 15's, as a base for a wingless dipole panel for the other erivers.

~Jon

**Paul H** · 13 February 2005, 22:13 Sunday

Originally posted by JonMarsh

Nice clean layout- reminds me a little of the Whisper Klones - what do you have in mind for the front panel?

This may be one of those things where you'll want to proto a few configurations until you're happy with how everything works. As low as you're crossing over from the 10's, I'd probably even consider a W cabinet with force cancellation for the 15's, as a base for a wingless dipole panel for the other erivers.

~Jon

I'm wayyyy off from thinking about specifics of the front panel panel - slow down!

The W-cabinet is an excellent suggestion if I indeed cross that low (ie 80Hz). I'll need to do some building, listening and testing first. I seem to recall Thomas commenting somewhere here not long ago that a W cabinet shouldn't be used over 100Hz, so if I'm at or over that I'll go with forward facing drivers and a heavily braced panel.

Next step - get some drivers ordered this week.

Paul

**JonMarsh** · 13 February 2005, 23:15 Sunday

I meant more like front panel material or thickness. I have mixed feelings about the W configuration, due to the cavity effects, but for larger drivers and lower crossover frequencies it might make a lot of sense... I only briefly considered it for the Arvo, because I really wanted a dipole bass that could cut it up to 150 or a bit more with one driver - not many that will do that, because of VC inductance. But you're got a nicer situation anyway, because you won't have to work the 7's hard at all, and that will keep the upper mids and lower presence region nice and clean- the 10's will carry the weight in the power region. I've been considering various add on's for the very bottom end of the Arvo's, which is what your 15" Stryke's will do- whether I go that way depends on how the TC2+ hold up, and of course, the Saint-Saens, which will really need something like that.

So I'll be looking over your shoulder a little to see how things work out for you with the Stryke 15's.

**Dennis H** · 14 February 2005, 00:16 Monday

Cavity effects - SL's studies seem to imply that the resonance frequency is higher for a W-frame than for an H-frame with the same D, although the Q is higher for the W-frame. A W-frame may actually work better. Or not....

W-frame, D=19"

H-frame, D=12" (Fres should be 50% higher)

**capslock** · 14 February 2005, 06:16 Monday

Originally posted by JonMarsh

That's rather a shame, isn't it?

BTW, do you know when the new Peerless Exclusive series will be available in Europe? I'm hearing one to three months from the distributor in the US.

~Jon

Well, the problem is we have only one distributor, Intertechnik, who has apparently been granted exclusivity for Germany, the Netherlands and maybe a few other countries. They are slow to take new drivers into their program, and their suggested retail prices are ususally nearly double the Madisound price, even if you consider that 16% sales tax are already included.

All the dealers have to buy through Intertechnik, so the best prices one can find are 20-25% below suggested retail, still expensive. OEMs have to order small quantities also through them, so while I have a few OEMs at hand, when I want something they are not buying regularly, they are not much cheaper.

One thing they do for their money is renaming and repackaging the drivers, and they do it badly. They have a couple of standard sizes for styrofoam boxes, and in some cases, this means the driver is sitting on its surround. Just received a pair of L18s with the spider moved permanently inwards by 3-4 mm. Upside down storage on a radiator didn't solve the problem, but a hairdrier did. Same thing for HDS134 a while ago.

And their technical support is incompentent. While their online catalog was still showing the old L18 H1142,I asked them when they would have the new H1224. It took them two weeks to reply that they never had had and didn't know any H1142 (which happened to have been in a couple of printed and online editions of their catalogue). Two months later, the online catalogue was updated, and at about the same time I learned that they had been shipping the H1224 for at least half a year.

*end of rant*

This is why I often buy from Madisound and carry the stuff home or ask colleages to take it with them.

**JonMarsh** · 14 February 2005, 11:05 Monday

Originally posted by Dennis H

Cavity effects - SL's studies seem to imply that the resonance frequency is higher for a W-frame than for an H-frame with the same D, although the Q is higher for the W-frame. A W-frame may actually work better. Or not....

W-frame, D=19"

H-frame, D=12" (Fres should be 50% higher)

I don't like the W dipole cabinet based on it's inherent acoustical properties, but it may be a workable, valuable compromise based on compactness, and the force cancellation of the driver motions- one less thing to "rock the boat", so to speak.

The acoustical performance is more of a liability, and I'm wondering to what degree that can be ameliorated by using somewhat larger dimensions internally and a big bigger cavity. Now, we could sure use a simulator for that!

Slightly OT, but does anyone else find Linkwitz's page "Orion by the Sea" rather funny (I almost snorted my latte this morning!), pitching renting his vacation home ("Honeymoon Cottage") so that one can hear the Orion speakers?

Orion By the Sea

Well, I can imagine it's not easy making an extra buck or two here and there when you're retired...

**JonMarsh** · 14 February 2005, 11:10 Monday

Originally posted by capslock

Well, the problem is we have only one distributor, Intertechnik, who has apparently been granted exclusivity for Germany, the Netherlands and maybe a few other countries. They are slow to take new drivers into their program, and their suggested retail prices are ususally nearly double the Madisound price, even if you consider that 16% sales tax are already included.

All the dealers have to buy through Intertechnik, so the best prices one can find are 20-25% below suggested retail, still expensive. OEMs have to order small quantities also through them, so while I have a few OEMs at hand, when I want something they are not buying regularly, they are not much cheaper.

One thing they do for their money is renaming and repackaging the drivers, and they do it badly. They have a couple of standard sizes for styrofoam boxes, and in some cases, this means the driver is sitting on its surround. Just received a pair of L18s with the spider moved permanently inwards by 3-4 mm. Upside down storage on a radiator didn't solve the problem, but a hairdrier did. Same thing for HDS134 a while ago.

And their technical support is incompentent. While their online catalog was still showing the old L18 H1142,I asked them when they would have the new H1224. It took them two weeks to reply that they never had had and didn't know any H1142 (which happened to have been in a couple of printed and online editions of their catalogue). Two months later, the online catalogue was updated, and at about the same time I learned that they had been shipping the H1224 for at least half a year.

*end of rant*

This is why I often buy from Madisound and carry the stuff home or ask colleages to take it with them.

Folks look at me with a blank stare around here when I tell them that Europe is rather retail customer hostile, with complex distribution systems resulting in rather high markup to the end customer. Your "rant" is just another example, along with CD's priced at 20 lb sterling, etc. It's down right weired that you have to go to the USA to buy European drivers at a good price...

Still, you've really raised my interest in this new series- especially if the distortion performance is similar to the PP HDS parts. Almost makes me itchy to order some of the current ones, but I think discretion is the better part of valor, and I'll wait until the new ones turn up. Solen has them listed, but I'm guessing they can't deliver yet- buying through Canada is a hassle, anyway.

Best regards,

Jon

**ThomasW** · 14 February 2005, 11:43 Monday

Those wanting so share Siegfried's little slice of paradise can buy in to the community....... :wink:

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**Davey** · 14 February 2005, 12:07 Monday

Jon,

I don't think that's "his" vacation home. It's just one of many homes available in that vacation "complex" which are owned by someone else. I don't believe there's any financial incentive for SL. I think it operates more like a timeshare setup. I could be wrong.

Yes, the "W" baffles are somewhat complex, but I think the force cancellation is viewed by many folks (at least those that understand it) as a minor advantage to this configuration. I believe it to be a major one. Listeners with excellent room construction or slabs wouldn't really appreciate the difference, but for rooms like mine it really tips the balance.
I've tried a few "W-enclosures" bigger than the Phoenix setup. It shifts the resonant point somewhat, but not enough to make a considerable difference. The whole idea here is to operate the system below this point. If higher frequency extension is required then it's time to switch to a conventional (maybe 4-way) setup much like the Beethoven series. I think SL is fairly clear on his explanations of the limitations of the "W" frame setup.

Paul,

The xover frequencies are 120Hz and 2000Hz for my system. I'm sure Jon and others will note that the driver spacing, xover frequencies, etc, etc, of the system break many of the conventional rules, but what the hey. If a guy can't break a few rules now and then where's the fun in that.

Cheers,

Davey.

**JonMarsh** · 14 February 2005, 12:43 Monday

Thanks for your comments regarding the W enclosure- including your feedback about larger W enclosures. I was wondering if a slight shift upwards or Q reduction was possible- it sounds like, from what I've seen, it's going to have the same issues as an IB manifold, which means realistically about an 80 Hz crossover when all's said and done. I used to do slot loaded 15" subs in the 70's and early 80's, and they had similar issues affecting the response above 100 Hz.

~Jon

**Davey** · 14 February 2005, 13:25 Monday

In my limited experience it's difficult to estimate the response peak based on cabinet dimensions alone. The driver itself figures into the equation also with how it interacts with the enclosure. Some drivers have a pole vent with some space that must be allowed for and some you can pack in a little "tighter" etc, etc. I think it's kind of a build it and try it situation.

A couple years ago I transplanted the Madisound 1252DVC drivers from my Phoenix system into a wider and deeper W enclosure expecting to achieve a little better pre-EQ'd response, but it didn't work as expected. Maybe the angled baffle approach that Monte and SL have used might be a better solution, but I haven't tried that yet. Screwing everything together initially is a good idea.....if you have to tear it down later it's no big deal.

Yeah, I think you're correct. An 80-100Hz crossover is about the limit for a "W" baffle....unless somebody has a magic solution that I'm not aware of.

You have to give these "H" and "W" baffles some credit though. They achieve pretty darn good results with a minimum of space without having to resort to larger and more involved setups like IB's.

Cheers,

Davey.

**JonMarsh** · 14 February 2005, 14:03 Monday

Originally posted by Davey

You have to give these "H" and "W" baffles some credit though. They achieve pretty darn good results with a minimum of space without having to resort to larger and more involved setups like IB's.

Cheers,

Davey.

Well, that is my reasoning for the W cabinet- trying to figure out something that will NOT be built in, but trying to keep it compact. Another possibility is a force canelling sealed enclsoure below 75 Hz with lots of power and LT transform- but I think I'm willing to spend extra bucks and go dipole if I can keep the forward size at bay... I'm still thinking in terms of multiple 12s, because it would be easier to move around when needed, too. Maybe modular... stack 'em like PA bass bins, you know?

~Jon

**Dennis H** · 14 February 2005, 16:02 Monday

Davey, have you tried damping the cavity resonance? Above 200 Hz, where the worst problems seem to be, I'd think a few inches of fiberglass stuffed in the back of the cavity might help.

**Davey** · 14 February 2005, 17:32 Monday

No, I didn't, but worth a try. There's a cavity front and back so aesthetically it might not look very neat unless there's some covering.

Cheers,

Davey.

**Paul H** · 14 February 2005, 21:03 Monday

Originally posted by JonMarsh

I meant more like front panel material or thickness. I have mixed feelings about the W configuration, due to the cavity effects, but for larger drivers and lower crossover frequencies it might make a lot of sense...

The front panel material will likely be thick multi-layer ply/mdf with veneer. I'm envisioning something that is curved backwards at both sides, rather than just rounded off at the corner. Veneer and stain type will just depend on my mood and how the drivers look assembled. Bird's eye maple with a red-wine colored aniline dye to make the grain pop? ... hmmm.

I think I'll stay away from w-cabinets based on comments here so far - I can build a heavy cabinet which will sit on a carpeted concrete slab, so the force cancellation isn't critical, and there are a bunch of potential negatives with sound quality.

Originally posted by JonMarsh

...I've been considering various add on's for the very bottom end of the Arvo's, which is what your 15" Stryke's will do- whether I go that way depends on how the TC2+ hold up, and of course, the Saint-Saens, which will really need something like that.

So I'll be looking over your shoulder a little to see how things work out for you with the Stryke 15's.

You'll be looking over my shoulder to see my results! :roll: no pressure here ... :lol:

Paul

**capslock** · 15 February 2005, 15:32 Tuesday

Originally posted by JonMarsh

Folks look at me with a blank stare around here when I tell them that Europe is rather retail customer hostile, with complex distribution systems resulting in rather high markup to the end customer. Your "rant" is just another example, along with CD's priced at 20 lb sterling, etc. It's down right weired that you have to go to the USA to buy European drivers at a good price...

Still, you've really raised my interest in this new series- especially if the distortion performance is similar to the PP HDS parts. Almost makes me itchy to order some of the current ones, but I think discretion is the better part of valor, and I'll wait until the new ones turn up. Solen has them listed, but I'm guessing they can't deliver yet- buying through Canada is a hassle, anyway.

Best regards,

Jon

Well, it really depends on the product or service you're looking at. The problem with Intertechnik compared to say Madisound is that there is one more dealer down the line (you normally buy from a dealer who buys from Intertechnik who buys from d-s-t, and if you buy from Intertechnik directly, they stick to their suggested retail prices in order not to hurt their dealers). Also, they have essentially no competition, because any startup company would have to order about 50 - 100 drivers per model, which is a huge initial investment. And I wonder what's going to happen to Madisound prices now that PE have dropped most d-s-t products and only Solen remains.

If you were to buy drivers in a retail store in the US, there'd be a similar markup.

And a 20 lb CD sounds outrageous. We pay 13-16 Euros for a regular-priced CD, including 16% VAT (which, in spite of our federalized structure, cannot be evaded). So on the long term average Euro/$ exchange rate, this is about equal. And we do get a two year warranty on all goods (which I don't care about in the case of CDs, but which comes in handy with all kinds of equipment).

There are funny retail structurs in the US, too. Wine, no matter whether domestic, European or Chilean, is about twice what it costs here. Cheese can be really weird. I remember looking at a 125 g package of Boursin, a mass produced, definitely non-gourmet soft cheese that sells for about 1 Euro here costing $7.99 in a US supermarket. Domestic cheese is also surprisingly expensive.

Of course, Japan beats that, too, the same cheese costing Yen 1100, and really poor German wine selling for Yen 2000.

Retail structures can be really hard to understand. I used to joke with a Japanese business partner from whom we buy optical glass that we should open a wine distribution joint venture, and that we'll all get rich by paying for the glass in wine.

**Paul H** · 15 February 2005, 21:52 Tuesday

Okay, no more feedback on the best drivers for use in my dipole ... because I've ordered all of them now.

Waiting as fast as I can,

Paul

**capslock** · 16 February 2005, 04:26 Wednesday

Originally posted by Paul H

Waiting as fast as I can,

:wink:

**Paul H** · 18 February 2005, 20:02 Friday

Got a box today in the mail marked "Heavy"

It included the tweeter, mid and 10's.

No word on the 15's yet - different supplier.

I'll start cutting scrap and testing hopefully this weekend.

Paul

**JonMarsh** · 19 February 2005, 00:08 Saturday

That's what I like- a man who moves quickly! Getting in new parts to try out is half the fun, for sure...

~Jon

**Mark K** · 19 February 2005, 00:36 Saturday

Sea Ranch is a funny place. I've had the pleasure of staying there, though not in the honeymoon cottage. My guess it was the standard second home by the sea onclave/tax write off of the 1970's for the affluent Bay area types. Like everything else by the sea in CA, the prices are ridiculously high. Of course, a starter home in Sac is 400k, so what's 1.2m for an ocean view... :B And Jon, can you buy a detached house in the Bay area for less than 800k?

It's hard to get to, but probably worth taking a couple day vacation there. Personally, I find the architecture not to my liking, but the natural beauty is quite remarkable. Anyway, unlike Jon, I didn't find the ad for the honeymoon cottage all that odd. After all, nobody lives in those homes, well, not really. What do you do with your second home when it's paid off and you can't write it off anymore? Why, you rent it out...

**JonMarsh** · 19 February 2005, 01:59 Saturday

I understand your logic, Mark, but logic wasn't part of my original reaction...

Well, according to the Mercury News last week, prices have risen 20% in the last 12 months, reaching a median for Santa Clara county of $620K. Bay area overall is about $540K median; that includes all the "low buck" areas... heck, an 1800 sq ft detached house in Tracy is in the high 400's these days. Some townhomes just went on the market in Livermore, they're cute looking, but small, and in a terrible location just before an overpass on one of the busiest streets in Livermore (1st St, just East of downtownj area), entry ways RIGHT up on the street, and two bedrooms start in the high 500's. Ludicrous. Especially funny if you read the ad copy, and they way they're trying to talk up the immediate area, you'd think it was Pleasanton instead of Livermore they were talking about. In Livermore, a newish 2000 square ft place is ~750-800K. More further west, of course.