CHEAP, High Efficiency Open Baffle

**cjd** · 27 February 2007, 09:58 Tuesday

Whatchoo call cheap?

I assume you're looking at 2 of any of the woofers you're listing?

And how LOW do you want this sucker to go? That's where expense can really start to climb.

C

**augerpro** · 27 February 2007, 18:34 Tuesday

Originally posted by cjd

Whatchoo call cheap?

I assume you're looking at 2 of any of the woofers you're listing?

And how LOW do you want this sucker to go? That's where expense can really start to climb.

C

I don't know that I could get much cheaper! Do you knwo of some vendors with decent quality but cheap PA drivers. Hook me up Chris!
I just started to read up on dipoles so is this right: 6dB loss due to BS, and an additional 6 dB loss due to cancellation? So yes, 2 woofers on each side would be mandatory I would think. None of the PA drivers seem to go particularily low so I'm thinking of handing off the bass to my sealed subwoofer around 60-80 Hz.

**MuaDibb** · 27 February 2007, 19:40 Tuesday

I noticed one of your woofers was the Eminence Beta. Maybe check out the Bastanis website. It is rumored that this or something very similar made by Eminence is the basis for his loudspeaker. The 12" he uses, and is treated by his "exclusive" methods runs up to about 10K where it crosses to a supertweet. I think the beta goes to about 8K. You could do something similar for not alot of money. He uses a sealed sub for the low end too. I did a lot of searches with the intention of trying a clone of sorts.

404-Error: 404

http://www.bastanis.de/us/prometheus+mkii.htm

If you find that to be interesting I might be able to dig up something from DIY.com, I think someone made one, but used a phase plug to even out the Beta, maybe the guy from Planet10 made the phase plugs. Good luck.

**Tommythecat** · 27 February 2007, 19:59 Tuesday

1) Don't try to use a 12" woofer over 2k. Even that's sketchy.

2) "Dipole tweeter"? "Efficiency of the bass unit is not relevant since it is active."? Who are these guys kidding? Oh right, crossoverless wideband idealists...

**MuaDibb** · 27 February 2007, 20:17 Tuesday

Sorry, it was the Beta 12LTA with that stupid wizzer I was refering to. You just rip that puppy out, install a phase plug and your good to go. :E

And Tommy what do you mean? Can't use a "woofer over 2K? Its a WIDEBAND! :P

I mean people are paying thousands of dollars for these. :T

As far as sound, I've never heard one, so I can't say whether it works or not or sounds good or bad. Just more info. :W

**Saurav** · 27 February 2007, 20:27 Tuesday

Images not available

Open baffle: Fountek JP3.0, Audax PR170M0, Both are 95dB+ I think. LR4 @ somewhere between 3500 and 4500. Driven by a 3.5W SET amp.

Woofer: Peerless HDS 10", sealed enclosure, driven by a Gainclone, ~25-35W.

Behringer CX2300 active XO between the woofer and the panel, @ ~375Hz. That's roughly the frequency at which the panel starts to drop off, I haven't applied any dipole EQ to the top.

BFD, Behringer A500, NHT1259 in a sealed enclosure, XO @ 50Hz I think, it'll be 80 once I get 3400 or something else that can high-pass the woofers.

"Efficiency of the bass unit is not relevant since it is active."?

English isn't their first language

I think what he's trying to say is that the woofer is driven by an internal amplifier, so you don't need to look at its efficiency when choosing an amp to drive these speakers. At least, that's how I would read it.

**augerpro** · 27 February 2007, 22:17 Tuesday

Saurav is the Audax the only driver running dipole on your speaker? Also what kind of SET amp are you using?

I'm trying to keep this cheap, but I found some PHL 1180s for $70 apiece. 98 dB, Fs 130, and +/- 2mm excursion which is the same as Xmax of 4mm I think? Qts is kinda low at .36 but I don't think this will matter much in a mid.

**Saurav** · 27 February 2007, 22:20 Tuesday

Saurav is the Audax the only driver running dipole on your speaker?

Yes. It's backwards - the bass should be dipole

The lower cabs were built for a different speaker, then scavenged for this one. If I were starting from scratch, I don't think I'd build it this way.

Also what kind of SET amp are you using?

A DIY 2A3 amp.

**augerpro** · 27 February 2007, 22:31 Tuesday

Are there any public designs for your amp? I'm thinking of trying this one: http://www.lh-electric.4t.com/sta44.htm

**cjd** · 27 February 2007, 22:58 Tuesday

So, here're my thoughts on this subject.

First, forget about getting solid bass out of this. Just aim for good 'nuff.

Then find yourself drivers at acceptable prices that pretty much mirror the Arvo project, and "clone" that with the higher efficiency target in mind.

The B&C 6.5" midrange has a falling response already, it's really wanting to be horn loaded. The B&C 8" midrange looks superb but it's not what I would call cheap.

Trying to fill out the bottom end is going to take displacement. No way of avoiding that.

So, I have these dipoles I use with a 4" buyout driver and a tiny buyout tweeter. Under $10 in parts total.

Why not grab a cheap but decent 8" + tweeter and start out with that, just have fun with it?

I would keep your tube experiments separate from your speaker experiments.

You CAN run low efficiency speakers on a tube amp, you just can't play them very loud. But that's STILL enough to tell you what you want to know.

I just see this as a set of projects that could lead to excessive angst.

C

**Saurav** · 27 February 2007, 22:58 Tuesday

Are there any public designs for your amp?

Nope. I started with a public design, either on the JE Labs website or somewhere else, then I tried some other things, then I bought a book and learnt the math and asked questions on DIY Audio and designed a new driver stage... and that's where it's been for the last few years. I don't even remember what the current driver stage setup looks like any more.

**Tommythecat** · 28 February 2007, 00:05 Wednesday

That makes sense Saurav...in a depressing way..

**augerpro** · 28 February 2007, 00:11 Wednesday

Originally posted by cjd

So, here're my thoughts on this subject.

First, forget about getting solid bass out of this. Just aim for good 'nuff.

Then find yourself drivers at acceptable prices that pretty much mirror the Arvo project, and "clone" that with the higher efficiency target in mind.

The B&C 6.5" midrange has a falling response already, it's really wanting to be horn loaded. The B&C 8" midrange looks superb but it's not what I would call cheap.

Trying to fill out the bottom end is going to take displacement. No way of avoiding that.

So, I have these dipoles I use with a 4" buyout driver and a tiny buyout tweeter. Under $10 in parts total.

Why not grab a cheap but decent 8" + tweeter and start out with that, just have fun with it?

I would keep your tube experiments separate from your speaker experiments.

You CAN run low efficiency speakers on a tube amp, you just can't play them very loud. But that's STILL enough to tell you what you want to know.

I just see this as a set of projects that could lead to excessive angst.

C

I definately don't want to over complicate this. I'll keep my expectations realistic and I won't be let down. The Arvo is definately an inspiration. I was thinking more like TMWW though. I would like to stay with dipole woofers, not sealed. What do you think? Were you suggesting just a TM dipole and leave bass to my sealed sub? I won't be expecting earth shattering bass.

I'm thinking this is the woofer to use:

Page not found

http://www.partsexpress.com/pe/pshowdetl.cfm?&Partnumber=290-382

For the mid what do you think of these:

Page not found

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=290-020

Or if I really want spend a little money the PHL 1180 on sale at Zalytron might be worth it?

For a tweeter I'm thinking Dayton ND20 or maybe HiVi K1. Possibly waveguide loaded.

As far as mixing the amp in I'm a multitasker man! Seems like fun anyway.

**JonMarsh** · 28 February 2007, 01:24 Wednesday

Originally posted by augerpro

Saurav is the Audax the only driver running dipole on your speaker? Also what kind of SET amp are you using?

I'm trying to keep this cheap, but I found some PHL 1180s for $70 apiece. 98 dB, Fs 130, and +/- 2mm excursion which is the same as Xmax of 4mm I think? Qts is kinda low at .36 but I don't think this will matter much in a mid.

+/- 2 mm excursion = xmax of 2 mm.

This is NOT the way to go dipole; you need more excursion for a diople woofer than a box system woofer, (for the same Sd), typically 4X more. Or 2x more drivers and 2x more Xmax.

I've seen a lot of talk about high efficiency 12's, covering bass through 2 kHz with a 12" woofer, and while I don't want to throw a wet towel on individual creativity, I'd sure hate for you guys to spend money on something that doesn't come close to meeting your hopes and expectations... 'cmon, a molded paper suspension 12" guitar speaker?

The cheapest single driver dipole woofer recommendation I would make is a Dayton RS390HF. Has some real Xmax (14 mm), some real swept Sd (it's a 15" driver, afterall), decent sensitivity due to 4 ohm impedance (90 dB/2.83VRMS), and pretty clean pistonic response to several hundred Hz.

I don't think there's much point picking a speaker just because it's 94 dB/watt sensitive, but with the cone suspension design and Qts it really only works down to a little below 100 Hz. Maybe I'm just being a grumpy curmudgeon here, but be careful how you spend your money!

It took a lot of looking to come up with something with a response profile like this....

Image not available

This is the Ciare 18.00 ND W1, 18" pro woofer, accordian cloth suspension, Neodymium magnet, about $200.

**augerpro** · 28 February 2007, 01:56 Wednesday

I see Jon. Well that's a bummer. I would assume Xmax for a mid crossed at 400Hz probably isn't that important? Of course that probably doesn't matter if no pro woofer has the Xmax to reproduce the frquencies below that. Hmmm. Back to the drawing board I guess.

**MJKing** · 28 February 2007, 07:43 Wednesday

I have proposed this driver combination in the past but nobody has taken me up on it yet. I have not done any extensive design work, but consider this combination as a starting point.

Full range driver = Fostex FE-167E or 166E, each is 94 dB efficient ($63 each)

15" Woofer = Eminence Alpha series 15A, 97dB efficient and Qts = 1.26 ($58 each)

or

15" Woofer = Eminence Beta series 15, 98dB efficient and Qts = 0.59 ($72 each)

Crossover = Behringer CX2310 ($90)

XLR Cables = six required ($50)

Total Cost = 2 x $63 + 2 x $58 + $90 + $50 = $382 plus wood.

I can say that a 15" woofer with a full range driver is extremely efficient and produces great dynamics. You can see my Project 7 for an example of this type of system. Again, I have done no detailed design work but this still looks to be a good starting point at a reasonable cost. I have uploaded a sim on my site if you are interested.

http://www.quarter-wave.com/Models/OB_2_Drivers_1_30_07.pdf

**cjd** · 28 February 2007, 09:58 Wednesday

Hmmm, no amps Martin?

Oh yeah, he wants his tube friend, but he'll need more going active. Just funny to read the list having temporarily forgotten previous discussions on amplification. Guess I need some coffee! Kinda had to run to make my morning train, on which I now sit... It's good to see you pipe up now and again

That's the kind of direction I think is sensible for Brandon given his experimental state, regardless. In fact I think Saurav has some sense in his mixed amplification, tube/solid state. Sure, a tweeter of one sort or another could be added into the mix as well at some point. And bass isn't going to be impressive but crossing into a monopole at 80Hz or 100Hz (which is not as low as I might consider ideal but you're experimenting! Plenty of time to beef up the bottom end later if you love the results - that's the point of MKII or MKIII or MKCIV

)

That said, there may also be some value in working out a passive crossover as well. Pick the drivers right and accept beaming and lower order slopes are probably quite reasonably done.

C

**JonMarsh** · 28 February 2007, 10:19 Wednesday

Originally posted by augerpro

I see Jon. Well that's a bummer. I would assume Xmax for a mid crossed at 400Hz probably isn't that important? Of course that probably doesn't matter if no pro woofer has the Xmax to reproduce the frquencies below that. Hmmm. Back to the drawing board I guess.

Hey- that 18" Cirare woofer I posted the plot of above is over 94 dB efficient, and Does have 8 mm Xmax; though the Xmax isn't all that high, the Sd makes up for it. But most of the "pro" drivers being posted are NOT woofers with response down to below 40Hz and Fs of 32 Hz, they're guitar speakers with 1.25 mm Xmax that drop like a rock below 100 Hz.

Even some of the 18sound drivers proposed fall in that category (for High efficiency woofer to match to waveguide).

Xmax in a midrange OR woofer for a given SPL and frequency range can be nicely evaluated by SL's SPL_Max spreadsheet, which will run in any of the Excel klones, including Open Office, as it doesn't use VBA. So, it's FREE, folks just gotta use a little time and effort, not just make wild guesses and hopes (remember, I'm an engineer by profession, so I expect a systematic approach to problem solving and evaluation).

Yeah, a mid doesn't need much Xmax if you've got a decent size baffle and you're crossing over at 400Hz, but take it down to 150 Hz with the same size baffle and it's quite another matter (thats why SL using a moderately long throw 8" midwoofer as a midrange)(13" baffle seems popular here, though I've been a 15" asymmetric kind of guy myself, now moving up to slightly larger asymmetrical baffle style)

Just run the numbers, look at the T/S parameters and the vendor plots, if you see a driver with 1 mm Xmax and response that falls like a rock below 100-120 Hz in a box, you can bet your sweet bippy it's not going to put out anything resembling bass in a dipole configuration. 12" or not...

I'm just suggesting a slightly more rigorous approach to driver selection than "wishin, and hopin, " as the old song would go.

**cjd** · 28 February 2007, 10:39 Wednesday

Not enough rigor... we need to build our own.

**Saurav** · 28 February 2007, 12:14 Wednesday

That said, there may also be some value in working out a passive crossover as well.

Hmm... I dunno, not if he's going to run the whole thing off a tube amp. I think running bass through a budget tube amp kit could cause output transformer saturation and other issues. And then the amp becomes the choke point for dynamics instead of the speaker, which is just backwards. I've been there

Or you need a 50-100W tube amp, and that starts to get expensive.

In fact I think Saurav has some sense in his mixed amplification, tube/solid state.

Really

**Doug Lockwood** · 28 February 2007, 14:12 Wednesday

Hmm... I dunno, not if he's going to run the whole thing off a tube amp. I think running bass through a budget tube amp kit could cause output transformer saturation and other issues. And then the amp becomes the choke point for dynamics instead of the speaker, which is just backwards. I've been there
Or you need a 50-100W tube amp, and that starts to get expensive.

I would like to disagree with your conclusions.
With a 98 dB 15 inch driver, at 40 Hz you are much more likely to run out of xmax than saturate the transformer.
Even if the transformers are only capable of 4 watts at 40 Hz (disgusting, but plausible) that translates to 104 dB.
Much more likely the wimpy power supply has forced coupling caps with a 30 Hz f3 to avoid moterboating.
Morgan Jones has an excellent analysis of this in Designing Valve Amplifiers, 3rd edition.
With separate, or regulated power supplies and decent transformers with correct primary inductance, a small valve amplifier should be able to have good base to 40 Hz or below.

Doug

**Saurav** · 28 February 2007, 14:57 Wednesday

It's been a long time since I read Morgan Jones' book

With a 98 dB 15 inch driver, at 40 Hz you are much more likely to run out of xmax than saturate the transformer.

Agreed, you don't need a higher power amp if your driver has a high enough efficiency at that frequency. The 15" driver plot posted by Jon is < 90dB @ 40Hz, the 97/98 number applies up in the 200Hz region.

With separate, or regulated power supplies and decent transformers with correct primary inductance, a small valve amplifier should be able to have good base to 40 Hz or below.

Agreed, but that's a better amp than your average kit or free online schematic.

So... I'm not saying it (i.e. bass with a low power tube amp) can't be done. All I'm saying is that it'll take better-than-average drivers and amps to make it work, and it may not be easy to do a good job on the first attempt. I think using SS for the bass makes this an easier target to hit. *shrug*

**Dennis H** · 28 February 2007, 15:23 Wednesday

I would like to disagree with your conclusions.
With a 98 dB 15 inch driver, at 40 Hz you are much more likely to run out of xmax than saturate the transformer.

I'm not aware of any 15" drivers that will do 98dB at 40 Hz. The sensitivity spec is usually measured at a much higher frequency. Just grabbing a typical (but definitely not cheap) 15", the JBL 2226H, that I happen to have in SL's max SPL speadsheet.... The IB sensitivity is 99dB at 300 Hz but only 89dB at 40 Hz. To drive it to Xmax at 40 Hz requires a voltage equivalent to 96 watts into 8 ohms.

Edit: Cheap, High Efficiency, Open Baffle -- pick two.

**cjd** · 28 February 2007, 16:19 Wednesday

Hmm, I didn't know going passive automatically meant you had to ditch the concept of multiple amps.

**Doug Lockwood** · 28 February 2007, 20:24 Wednesday

I don't think there's much point picking a speaker just because it's 94 dB/watt sensitive, but with the cone suspension design and Qts it really only works down to a little below 100 Hz. Maybe I'm just being a grumpy curmudgeon here, but be careful how you spend your money!

John
I ran a simulation with the Eminence drivers Martin referenced. What I used is xbaffle, which Thorsten Loesch published and which seems more real-worked than the Linkwitz spreadsheet. Probably not as good as the MJK tools, however.

The 4 mm Xmax limited response below 80 Hz but the Alpha 15 was 95 dB down to 50hz with a 12 dB roll-off after that. Not half bad for $60 each. I have screen shots, I'll post them if I can figure out how. LOL

Doug

**Dennis H** · 28 February 2007, 20:46 Wednesday

Originally posted by Doug Lockwood

John
I ran a simulation with the Eminence drivers Martin referenced. What I used is xbaffle, which Thorsten Loesch published and which seems more real-worked than the Linkwitz spreadsheet. Probably not as good as the MJK tools, however.

The 4 mm Xmax limited response below 80 Hz but the Alpha 15 was 95 dB down to 50hz with a 12 dB roll-off after that. Not half bad for $60 each. I have screen shots, I'll post them if I can figure out how. LOL

Doug

Doug, here is Eminence's own graph of the Alpha 15 in an infinite baffle. Sensitivity at 50 Hz is 82dB and will be quite a bit worse in an open baffle.

**MJKing** · 28 February 2007, 22:10 Wednesday

Originally posted by Dennis H

Doug, here is Eminence's own graph of the Alpha 15 in an infinite baffle. Sensitivity at 50 Hz is 82dB and will be quite a bit worse in an open baffle.

Clearly the curve is not correct. A driver with a Qts of about 1.2 and an fs of 40 Hz does not roll off as shown in that curve. I believe the curve is not the Eminence driver in an infinite baffle but in some kind of enclosure.

**Dennis H** · 28 February 2007, 22:48 Wednesday

Originally posted by MJKing

Clearly the curve is not correct. A driver with a Qts of about 1.2 and an fs of 40 Hz does not roll off as shown in that curve. I believe the curve is not the Eminence driver in an infinite baffle but in some kind of enclosure.

Tell it to Eminence.

"The average output across the usable frequency range when applying 1W/1M into the nominal impedance. Ie: 2.83V/8ohms, 4V/16ohms.
Eminence response curves are measured under the following conditions: All speakers are tested at 1w/1m using a variety of test set-ups for the appropriate impedance | LMS using 0.25” supplied microphone (software calibrated) mounted 1m from wall/baffle | 2ft. X 2ft. baffle is built into the wall with the speaker mounted flush against a steel ring for minimum diffraction | Hafler P1500 Trans-Nova amplifier | 2700 cu.ft. chamber with fiberglass on all six surfaces (three with custom-made wedges)."

Sounds like an IB to me.

Why would we assume the listed Q specs are correct and the published curve is incorrect?

**augerpro** · 28 February 2007, 23:49 Wednesday

I'm confused now. Maybe I wasn't clear earlier but I will be crossing this speaker to a monopole sub. i said 60-80 Hz but 100Hz is possible too. Given that, I don't see how the 12" Goldwood or 12" Eminence Beta with the 6.5" PHL are so bad. I guess from JonM's post I thought he suggested the woofers don't have enough Xmax to handle the 100 Hz to 400Hz area. Reading it again I assume you mean less than 100Hz, which they won't be asked to do anyway being crossed to the monopole sub. So I could be okay with this driver layout then?

I'm not sure if I really want to go with the big 15" Beta Martin suggested. With a 100-400Hz passband am I really losing anything going witht hte 12"? Running down to 100Hz witha 24dB/octave rolloff i shouldn't hit Xmax with the power I have available. I have to model this in SE and see though. I narrowed down the woofer to the 12" Beta and Goldwood, finally deciding on the Goldwood due to price. The Goldwood woofer has a lower Qts but is that important if I'm only going to 100Hz? I'll consider the 15" but that is huge baffle. I do really like that Fostex driver though. Seems very nice though the Xmax is tiny, it would definately force a 400Hz or better XO. If xmax isn't that important in this range that looks better than any driver under $70 that I've seen. Again I'll have to model excursion in SE and see what happens. Martin just how fullrange are these really? Would they benefit at all from crossing to a tweet?

Concerning the amp. I could do hybrid and still use a passive XO correct? I could easily biamp running the SS to the woofer and tube to the mid/tweet. Also since I'm only going down to just under 100Hz (considering I'll use my recievers 24dB/octave bass management) I may be fine with a little tube amp running the whole speaker? At least to play with? Active is totally out. the cost goes way beyond what I envisioned for just a fun experiement.

I'll go back and reread everything since it seems i'll miss one little bit of info and that totally changes my outlook :roll:

**Saurav** · 01 March 2007, 00:08 Thursday

Active is totally out. the cost goes way beyond what I envisioned for just a fun experiement.

The Behringer CX2300 is a pretty good analog active XO, and it costs $89. I don't really understand how that blows the budget for 2 speakers' worth of drivers, XO parts, and 2 amps, unless you have spare XO parts and amps sitting around

Passive bi-amping would work. That's what Chris was getting at, I hadn't thought about that option. If you actively high-pass the signal at around 100Hz (i.e. make sure the tube amp doesn't see anything below that at its inputs), you could probably try it with a single amp. Hmm, but you want to run the woofers as dipoles... you'll need pretty wide baffles to get response down to 100Hz, I think...

FWIW, I used to own the Adire HE12.1s, which used an Eminence 12" driver and a coax compression tweeter. I drove them with 8W ASL amps. It sounded fine with a sub. Not very refined at all, but for my tastes in music, more fun to listen to than the mini-monitors I owned before those.

**Dennis H** · 01 March 2007, 00:25 Thursday

Maybe I wasn't clear earlier but I will be crossing this speaker to a monopole sub. i said 60-80 Hz but 100Hz is possible too.

That's great. With a dipole, crossing 1/3 octave higher means you only need 1/2 the displacement (or crossing 1 octave higher, you only need 1/8 the displacement). So, you can ignore all this chit-chat we've been having about what happens down at 40-50 Hz.

**augerpro** · 01 March 2007, 00:26 Thursday

Originally posted by Saurav

Hmm, but you want to run the woofers as dipoles... you'll need pretty wide baffles to get response down to 100Hz, I think...

I was playing with the Edge and response is dropping fast at 100 on a dipole. However the level from 100-200 is not all that different from 1000 Hz, but there is a hell of a hump between those frequencies centered around 400Hz. I used a baffle of 40cm x 120cm which is fairly close to what I think the reall one would be just ot get an idea of baffle diffraction. I'm not sure how easy it's going to be to cross at 400Hz or so. In my limited experience any big peaks or dips around the XO are huge PITA.

**JonMarsh** · 01 March 2007, 00:32 Thursday

Originally posted by augerpro

I'm confused now. Maybe I wasn't clear earlier but I will be crossing this speaker to a monopole sub. i said 60-80 Hz but 100Hz is possible too. Given that, I don't see how the 12" Goldwood or 12" Eminence Beta with the 6.5" PHL are so bad. I guess from JonM's post I thought he suggested the woofers don't have enough Xmax to handle the 100 Hz to 400Hz area. Reading it again I assume you mean less than 100Hz, which they won't be asked to do anyway being crossed to the monopole sub. So I could be okay with this driver layout then?

I'm not sure if I really want to go with the big 15" Beta Martin suggested. With a 100-400Hz passband am I really losing anything going witht hte 12"? Running down to 100Hz witha 24dB/octave rolloff i shouldn't hit Xmax with the power I have available. I have to model this in SE and see though. I narrowed down the woofer to the 12" Beta and Goldwood, finally deciding on the Goldwood due to price. The Goldwood woofer has a lower Qts but is that important if I'm only going to 100Hz? I'll consider the 15" but that is huge baffle. I do really like that Fostex driver though. Seems very nice though the Xmax is tiny, it would definately force a 400Hz or better XO. If xmax isn't that important in this range that looks better than any driver under $70 that I've seen. Again I'll have to model excursion in SE and see what happens. Martin just how fullrange are these really? Would they benefit at all from crossing to a tweet?

Concerning the amp. I could do hybrid and still use a passive XO correct? I could easily biamp running the SS to the woofer and tube to the mid/tweet. Also since I'm only going down to just under 100Hz (considering I'll use my recievers 24dB/octave bass management) I may be fine with a little tube amp running the whole speaker? At least to play with? Active is totally out. the cost goes way beyond what I envisioned for just a fun experiement.

I'll go back and reread everything since it seems i'll miss one little bit of info and that totally changes my outlook :roll:

Take a look at your proposed crossover frequency, maximum SPL in the passband, and what you have to handle in the transition band with whatever slope or crossover you propose. You may find that to handle the transition band at your maximum desired SPL that you need more Xmax than your realize-

Now, I was assuming you want to use the woofer at least down to 60-70 Hz. 100 Hz eases things, but because your acoustical target is a combination of inherent driver roll off plus the electrical roll off, depending on the crossover configuration you choose, you may not wind up with much electrical roll off, unless you go with something steeper than a 4th order LR acoustical.

if you've already run all the numbers in detail, then accept my apologies for unnecessary meddling- I'm just inquiring and making suggestions to lessen the likelihood of unintentionally painting yourself into a corner. A $40 driver isn't very expensive, unless you buy a number of them then have to toss them and start over because they didn't really fit your base assumptions. Just urging a little caution and calculation...

~Jon

**augerpro** · 01 March 2007, 00:45 Thursday

Meddle all you want Jon! I definately appreciate your input :T I have not modeled these drivers yet. As far as excursion from say 200Hz (with 400Hz XO) I'm just relying on my memory of other drivers I've modeled and I don't remember much significant excursion there. Although when I see Xmax of 0.6mm it does make hesitate. I will have model those and see EXACTLY how little excursion there is because there isn't much room for error with that small of Xmax.

So you don't think my recievers 4th order bass management filter is steep enough? With the natural driver rolloff i would estimate at least 6th order at 100Hz. I better take a look at those FR graphs again to be sure though...

**augerpro** · 01 March 2007, 00:53 Thursday

How about this: http://www.parts-express.com/pe/psho...07&orefer=dotd

j/k that monstrosity would never be in my home

**Doug Lockwood** · 01 March 2007, 01:13 Thursday

Why would we assume the listed Q specs are correct and the published curve is incorrect?

Dennis H, you make a valid point. Why beleive some of the information. I tend to beleive the Specifications more than the mesurements, but I have no solid basis for that assumption.

Doug

**MJKing** · 01 March 2007, 06:50 Thursday

Originally posted by Dennis H

Why would we assume the listed Q specs are correct and the published curve is incorrect?

I don't assume anything. I measured the T/S parameters of the four I bought. The text is correct but the graph is not, I think they put the wrong plot into the data sheet. It is an obvious mistake.

**Dennis H** · 01 March 2007, 13:06 Thursday

Thanks Martin. Nothing like first-hand measurements to tell the real tale.

**augerpro** · 16 April 2007, 06:01 Monday

I think I've found some drivers that may make this project feasible. At least good enough to justify building it and seeing how it sounds. keep in mind these will be crossed to a monopole sub <100Hz. P Audio makes some decent drivers for a decent price. The woofers don't roll off quite as bad as other cheaper PA drivers I've seen. Unfortunately the specs and graphs seem a bit mixed up sometimes...

Anyway option 1: 3 way using this:http://www.paacoustic.com/Product_De...oductID=SN-8MB
or this: http://www.paacoustic.com/Product_De...ductID=SN-10MB
for the mids. For the woofer: http://www.paacoustic.com/Product_De...uctID=E10-200S
I have the most concerns with this one. For one it's kind of expensive. Also if I go with a flat baffle I get no bass. With say, a U baffle I'll regain some bass but I'll have to cross to the mid between 100-200 Hz and the woofer is starting rolloff there so I'm really not using the woofer much. Also the graph for the 8" is not right, I think that is actually for the 12".

Design option 2: 2 way with either of these for the woofer: http://www.paacoustic.com/Product_De...uctID=E10-200S

http://www.paacoustic.com/Product_Detail.asp?CatalogID=0103&ProductID=SN-12MB

I kind of like this one. Simple. Cheap. Will probably cause the least amount of hairpulling.

Or option 3 which is the same as option 2 but a 2.5 way. More trouble to design but could really help with bass rolloff problem. I'm not really sure what I'll use as a tweeter. My first thought is a HiVi K1 in a waveguide. Cheap, decent SQ, and should be able to just cross to the 12" woofer. Right now I'm making good progress on a baffle design on the Edge.

**augerpro** · 19 April 2007, 15:25 Thursday

Well I'm leaning towards a 3 way TMWW now. For woofers I have these coming:

Page not found

http://www.partsexpress.com/pe/pshowdetl.cfm?&Partnumber=290-382

I think that picture is wrong though, from the Goldwood site:http://www.goldwoodsound.com/woofers-huntington.html

The mid was hard to pick out. I really like the P Audio SN10MB. But that would drive the cost too high for an "experiment". So settled on this: http://www.partsexpress.com/pe/pshow...=264-332&DID=7

I remember JonMarsh saying acoustic solutions for acoustic problems. Well check out the FR for the Selenium: http://www.partsexpress.com/pdf/264-332.pdf

And here is the sim:

All the bumps and dips are like a mirror image! I'd like to say I planned that but I'd be lying...one strange thing though here is the same sim but with a 4 for Speaker source density:

What do you all recommend for that setting? I suppose on bigger woofers the difference would be very significant. Oh and I have the HiVi K1 and some waveguides on the way too. Sensitivity at the XO should match ok, though it will start to roll off as the waveguide has less of an effect. So what do you guys think so far of this?

**augerpro** · 18 May 2007, 14:59 Friday

I need some advice on driver layout. My baffle is shaped somewhat like the Isiris. Mid/tweet are offset for smoothest response. What I don't know is if I should offset to the outside or inside? On a normal speaker the polar response gets "dragged" to the short side, so I would usually go with that, but I'm not sure how a dipole affects this?

Also I ditched the 10" Selenium and K1. Got a DX25 and P Audio WN8S for testing. The WN8S is a pretty nice driver for $53.

I should have the results of testing up on photo-bucket today. BTW for anyone looking at the drivers I've put up so far, all of the SPL and CSD will be redone. I had some noise in all measurements that showed up around 3.8k and up. I was wondering why all my measurements looked like Zaph's but had these little ripples, noticeable on the tweeters. I went through everything, different baffles, different gate, different amp, almost bought a new mic when all that didn't work. Ended up being the mic stand. The plastic thing that holds the mic! Anyway I did some new measurements of the 810921, SS 9800, and DX25 and they look good now. I should have all the rest redone this weekend.

**augerpro** · 18 May 2007, 20:53 Friday

We have winner! This WN8S isn't too bad. F3 is pretty high but it does everything else I need it to do well enough so I'm going to go ahead with it. I don't think I could find a better replacement for under $50 anyway...

Impedance is pretty smooth for a paper PA driver too. And the sensitivity of the DX25 in a waveguide matches well, except for the upper frequencies, meh...

**Rudolf** · 19 May 2007, 16:28 Saturday

Brandon,
regarding Speaker source density in EDGE: You should at least set the density to 10 to get acceptable results. Just have a look, how the diagram varies when changing the density from 1 to 10 or more.

Regarding driver offset: On a dipole speaker the polar response gets "dragged" to the short side as well. What´s more important: To the short side you get a more even decrease with rising angle for different frequencies.

Rudolf

**WillyD** · 19 May 2007, 16:59 Saturday

Man, thanks a lot for testing that P Audio driver auger. I had been looking at a pair of those 8s for a project but I didn't know how good/bad they were.

CHEAP, High Efficiency Open Baffle

CHEAP, High Efficiency Open Baffle

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