Poor Man's Ardent inspired design and build

[benthe8track]

Lots of different ideas about what makes sense, is practical/audible, for sure. When I started modeling up the cab I ran some ideas by my old Mechanics of Materials prof and he basically said just build two and measure--which wasn't really feasible.

One thing we do know that depending on which numbers you use LBL has ~60% higher Young's modulus (elastic modulus) than BB plywood. That's essentially a measure of stiffness which in my mind makes it a better material. So just tell the cabinet maker that next time he asks

I can't even say if I could hear the difference between the Ardent cabs we built (BB,LBL, hardboard, gallons of epoxy) and an MDF version, however I'm glad to have had the chance to try something new (to me).

[shootinnutz]

Thanks Ben, will do. You wouldn't happen to have any extra baffles laying around? You guys did a great job with the ardent wavcor.

[BobEllis]

OK, thanks for the push, Ron. Moving and weather make it next to impossible to actually work on my speakers, but I did get my C90-6-079s on order. Still up in the air which tweeter I will use. The 6640 would make crossover easy, or I could continue my contrarian path and use TL's tweeter whether ceramic, carbon or Be.

I've got an old 2 cubic foot cabinet that housed a MTM that I am going to use to break in my UM10s while waiting for weather suitable for building cabinets. If they aren't up to the rest of the Ardent inspired build, L26RO4Ys will fit the same recess and the UM10s can become fill in subs in 5th Element's style of multiple subs.

That's the one down side of moving - I lose my quasi IB subs. Taking the easy way out, I will use PE finished boxes (also on order) and miniDSP to make a Linkwitz transform to get the extension and low Q desired. We are losing the gigantic armoire style "entertainment center" so a couple of 3 cubic foot boxes will barely be noticed.

Keep the progress reports coming, Ron. My practice build is still as mentioned earlier, RS225, ZA14, 6600. I'll need to buy the 6600s sometime soon, but I do have a couple other options to fill the spot until they arrive.

[5th element]

Sorry for chiming into this late I've been a bit busy myself lately which makes for a nice change of pace.

What Jon says basically echos my own thoughts on loudspeakers design - resonances are bad, regardless of where they are from - and avoiding them is usually a very good idea.

A lot of the time you can end up with impedance bobbles that correspond to some sort of resonance within the spider and this rarely shows up as any kind of distortion or frequency response issue, it's the dreaded cone edge/surround resonance that causes problems. Stiff cones, such as ceramics or metallics, are inherently free from these as are some of the other composites that try to blend rigidity with high internal damping. This is no easy task and most people tend to accept the limitations of true stiff cones to get rid of those resonances. Half of the problem is that the cone edge/surround problems almost always tend to crop up where our ears are most sensitive, the 1-3kHz area, some SEAS drivers show this at around 600Hz, which imo, is a better compromise, but still a compromise. Some 'exotic' materials do better than others, the B&W Kevlar FST driver, for example, do not have a cone edge/surround resonance issue, but their surround is quite different compared to normal drivers and could be half the reason why they are free from it. The B&Ws certainly sound crystal clear and ridiculously detailed. Stiff cones don't necessarily have their own sound character, it's more that they don't affect the sound in any detrimental way. People always talk about the cold nature of stiff coned drivers, but this is really more to do with their lack of any depression within the 1-3kHz range that is usually caused by the cone edge/surround resonance in other paper drivers, that and the added 2nd harmonic peak at the same frequency probably adds a degree of 'niceness' to the sound.

If a stiff coned driver is crossed over too high then this will also cause a large peak in the third harmonic to bleed through, once again within the 1-3kHz range, which is our alarm bell range. There is a reason why people like adding a small notch within this range, it helps to make things sound pleasant and is very effective in taking a hard edge away from the sound. Adding to this is the usual issue of people crossing 6" mid/bass drivers to 1" dome tweeters at around 3kHz, not only does this let the 3rd order peak through, but it also creates the classic 'wide-narrow-wide' dispersion pattern, which goes back to what Jon said a few days ago about why a 6" driver isn't really suitable as a midrange. The wide-narrow-wide pattern is again very good at making a speaker sound more forward than it should, another reason why a notch in the 1-3kHz area is useful. Crossover low enough, or use a wave guide and this issue goes away and you don't need the notch any more.

The W15 is a wonderful driver and sounds crystal clear but it does need to be crossed over at around 2kHz with a steep 4th order acoustic crossover to make the best out of it. This avoids wide-narrow-wide dispersion issues around the crossover frequency and keeps the 3rd order distortion peak completely at bay. It also has very impressive bass for the size of driver, though not quite on the same level as the Scan Speak revelators. You do pay for all of this with the drivers low sensitivity but most people don't see that as a problem. With the ZA14 Zaph specifically decided to try and improve upon the W15s weaknesses, mainly its low sensitivity and it's inherent need for a low crossover point. Zaph decided to reduce the drivers overall diameter slightly and as result push the resonance slightly higher up, but he also optimised the T/S parameters to get a couple more dBs sensitivity out of the thing. To put it simply it worked and combined with the brilliant motor resulted in a driver that makes for a much better midrange choice than the W15.

Right from the start SB acoustics have been bringing out drivers with well designed motors that use copper in all the right places. Some of the drivers do not include copper and that's a shame, but the ones that do have excellent measured performance. Sadly most of SBs drivers do use soft cones and these have the typical cone edge/surround resonance issue, but apart from that they are very well designed. The Satori has one of the best motors in the business, in fact it is the best motor in the business, but their cone choice was one of a compromise. A good compromise in some peoples eyes and I do not mind that they've gone the paper route, the paper cone of the Satori is, as paper cones go, excellent in design, it would just be nice if they made a metal cone version too! If I remember correctly though I originally recommended the SB drivers because of their low distortion but because they would also be very easy to work with. Zaph has measurements of them on his website and his blog.

The scanspeak 12MU does have some minor resonance issues within the expected range, but in comparison to others is very benign and it doesn't really affect the frequency response in the way that it does with other drivers. It has very low harmonic distortion, decent sensitivity and being small in diameter will definitely help you with the off axis response. I would most certainly want to keep the tweeter as close to it as possible and probably cross no higher than 3kHz to make sure that the off axis response doesn't droop at all around the crossover frequency as you go off axis.

[JonMarsh]

Ug,
Solen Canada has the Wavecor drivers on sale..............I bought 4..........so much for "Poor Man's Ardent". Now I am a poor man, but with excellent drivers for the Ardent!
SS 3004/6600 Tweeters
SS 12MU/4731 Mids
Wavecor SW223BD01

8 week wait for shipping because they only had 3 on hand. I'm in no rush.
Only the Tweeters weren't on sale, fate saw my refund check and decided to give it to Solen.

you go guy! :T You won't regret it... I'm sure Solen will find something worthwhile to do with your refund check.... :W

[Renron]

12mu/473100

Thanks for the encouragement Bob, Jon, and 5th Element.

5th Element, what a wonderful informative post, I enjoyed reading it very much.
I found an article from Voice Coil, June 2012 with a re-review of the ScanSpeak 12MU by Vance Dickason. In this article he takes another look at the 12MU with a slight design change from the original, which the response graphs shows. Most of the graphs on the "Interwebs" (as my son say's), are of the earlier version of the driver. Vance notes that design refinements extend the usable range prior to cone breakup. Notably from 3K to 5K. Not sure if the cone or spider was improved, but it worked. Most of the other T/S parameters of the two tested drivers were close to the original tests done in 2009.
Here is a link to a PDF of the article. Hope it's OK to post this. If not, Moderators please remove the link.
In figure 11 SPL vs. Freq chart the red line is the 2009 version and the black line is the 2012 model. The "camel back" humps are gone!

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&ved=0CDcQFjAE&url=http%3A%2F%2Fwww.pearl-hifi.com%2F06_Lit_Archive%2F15_Mfrs_Publications%2F40_Voice_Coil%2F2012%2F2012_4_Apr.pdf&ei=7FfSVJTKFZCgoQTw0oCICA&usg=AFQjCNF4tGImp0Foy6naTqP53bVSp_FfJw&sig2=ZPrH3aiwHJSYRasP3SRQvw&bvm=bv.85076809,d.cGU

Please understand that I am not questioning or refuting ANYTHING you say. I'm a noob with too much time on his hands who enjoys reading and learning from the more experienced members like youself. I would appreciate your feedback on this article, and the XO points as you see appropriate.

Thanks to everyone who makes this a great Sub-Forum. I'm an implant from a .......coarser ............ forum.

Ron

[benthe8track]

Thanks Ben, will do. You wouldn't happen to have any extra baffles laying around? You guys did a great job with the ardent wavcor.

Sadly no, there was one extra set for a local guy and they ended up with another forum member. Should be a lot of great builds to follow this year!

Renron, congrats on the purchase. You're going to love those wavecors.

[JonMarsh]

Thanks for the encouragement Bob, Jon, and 5th Element.

5th Element, what a wonderful informative post, I enjoyed reading it very much.
I found an article from Voice Coil, June 2012 with a re-review of the ScanSpeak 12MU by Vance Dickason. In this article he takes another look at the 12MU with a slight design change from the original, which the response graphs shows. Most of the graphs on the "Interwebs" (as my son say's), are of the earlier version of the driver. Vance notes that design refinements extend the usable range prior to cone breakup. Notably from 3K to 5K. Not sure if the cone or spider was improved, but it worked. Most of the other T/S parameters of the two tested drivers were close to the original tests done in 2009.
Here is a link to a PDF of the article. Hope it's OK to post this. If not, Moderators please remove the link.
In figure 11 SPL vs. Freq chart the red line is the 2009 version and the black line is the 2012 model. The "camel back" humps are gone!

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&ved=0CDcQFjAE&url=http%3A%2F%2Fwww.pearl-hifi.com%2F06_Lit_Archive%2F15_Mfrs_Publications%2F40_Voice_Coil%2F2012%2F2012_4_Apr.pdf&ei=7FfSVJTKFZCgoQTw0oCICA&usg=AFQjCNF4tGImp0Foy6naTqP53bVSp_FfJw&sig2=ZPrH3aiwHJSYRasP3SRQvw&bvm=bv.85076809,d.cGU

Please understand that I am not questioning or refuting ANYTHING you say. I'm a noob with too much time on his hands who enjoys reading and learning from the more experienced members like youself. I would appreciate your feedback on this article, and the XO points as you see appropriate.

Thanks to everyone who makes this a great Sub-Forum. I'm an implant from a .......coarser ............ forum.

Ron

The article looks solid, and the response is certainly nicer. Crossover points still tend to be a combination of the driver geometry and spacing, and the innate driver capability. I would use the same crossover points with this Scanspeak driver as for the Accuton; I deliberately moved the lower crossover point up a bit compared with the first version of the Ardent, both to rely a bit more on the robust power handling of the woofers in the lower midrange, and to reduce the size and cost of the crossover components.

We'll need measured data. Can you do measurements of the midrange, including impedance curve in the enclosure? Otherwise, I'd suggest you loan me one driver, and I can do test measurements here for you.

[Renron]

Jon, thank you for your very kind offer to test the mid driver. Don't you have enough on your plate? LOL. You are too kind. Thanks for trying to keep XO parts cost down.

I've bought hardware and software to measure drivers, and I'm not expecting my drivers to ship for about 8 weeks. Wavecor's were back-ordered and I didn't want to pay for shipping twice so i told them to wait and ship them all together. I may have to rethink that.
I've got the full Arta program as suggested by 5th Element, and all the hardware needed to start measurements, but, with no experience, it seems a rather steep learning curve. I'm lost at where to begin.
Is there a dummy's guide to Arta anyone knows of? A step by step process if you will.
It would seem logical to test the drivers on a baffle similar in size to the Ardent's, rather than a 2'x3' sheet of plywood (IB). Correct?

I think I saw that someone on the forum/threads lives in Rocklin, which is close. I might just ask them pretty please (and a six pack) for a quick lesson in measuring drivers. I've got some unknown drivers for a garage speaker build I was going to practice testing.

Slow work takes time.
Ron

Edit: found an article by Charlie Laub on how to use Arta. Thanks.

[5th element]

I do have this measurement guide for ARTA, I may have linked this before, I cannot remember, but here it is.

measurement guide-1.pdf

The 12MU is one of my favourite drivers from scans Illuminator range, in fact I tend to prefer the Revelator drivers on paper and in measurements, but the 12MU is excellent. The old 12M/4631G00 is terrible compared to how the rest of the Rev series performs and was a bit of an oddity in that regard. The 12MU on the other hand is one of the stand out products of the Illuminator range.

As Jon says crossover frequencies are usually more a function of geometry, this being driver separation, driver diameter and their relative path differences/phase responses. I would be looking at around 400Hz and 3kHz xover frequencies as starting points, providing the tweeter was mounted close enough. I am a bit of a stickler for excellent off axis performance though and I would be very tempted to cross the 12MU at around 2kHz, not just to completely clamp down on beaming issues, but also to improve the vertical off axis performance. From a technical stand point, to keep the vertical window 'perfect' over a wide range of off axis angles you need to keep the xover frequency at 2x the wavelength of the driver separation.

In other words if you've got 10cm between you're two drivers this sets that wavelength to 20cm. Then, to set your xover frequency, 340/0.2 = 1700Hz. This may come as a surprise and you'll probably think that this is crazy and surely then that everyone is crossing their drivers over way higher than they should. The truth behind this is that you really do need to cross this low if you want the vertical window to remain good over pretty much all angles. The real question though is if it's at all necessary. In my opinion it is. It's all a question of technical capabilities and compromises though. You do need to cross this low to keep the vertical off axis close enough to like you would see in a coax. As you raise up the xover frequency you start moving away from this and the sound does suffer from it. How much does it suffer? Well that's the million dollar question and it's entirely subjective, but it's also largely dependent on your room, the rest of the loudspeakers design and your listening position, or positions if you listen at different locations.

Usually there are other constraints that limit where you can place the xover frequency, such as the tweeter power handling and phase integration. Luckily for you the 6600 has very low harmonic distortion and a motor that will work pretty well crossed over low. It will certainly handle 2kHz with a 4th order acoustic xover, even at high volumes. Is it worth crossing over this low? Only you can be the judge of that and I would recommend experimenting if possible, all I can say is that there are good technical reasons for doing so, but as always it's a case of balancing trade offs.

[BobEllis]

Interesting, 5th. I was thinking along the same lines. With a C79's 130 mm faceplate and any standard tweeter, that gives you 120 mm between centers and pushes the crossover frequency down to 1440 Hz even if the drivers touch. You lose a little more with TL's round tweeters at 120 mm dia. I suspect that we get a little slop because the drivers are not point sources, I wouldn't go as far as to use the space between the radiating surfaces as the distance, but I think we can go further apart than center to center distance would indicate.

Anyway, these are nice to look at, still hoping for unseasonably warm weather to let me do something with them. I'm thinking that I can get away without flush mounting since I won't be going grill-less and need felt anyway. I may need to rig up something just to test them for function.

[5th element]

Well indeed the vertical off axis response is usually seen as largely secondary to other design criteria, but most designs get sloppy even with the horizontal off axis response, which imo, is a complete no no. Either use a tweeter that will allow you to cross lower enough to avoid midrange beaming, or use a wave guide and a suitable mid range that allows you to cross over high enough for a good directivity match. Of course using the wave guide will increase the C2C distance and as a result the vertical off axis response will deteriorate but that's a decent price to pay.

I know that the thought of flush mounting those square frame drivers is probably giving you nightmares but really you should investigate ways of making that happen. Not flush mounting always causes diffraction problems that you really don't want to deal with. When designing a crossover it's all those little wiggles and bumps that deviate from what would be normal that cause problems.

One of these would work well but you'd have to protect the drivers whilst creating the initial template from them. For the Accuton this would be very easy as all you'd need to do is tape up the front side to prevent dust from getting in and tape up the rear for similar reasons. The TL tweeter would be a tad harder as you'd need to protect the dome, but using some stand offs would be an excellent way of doing this.

Image not available

[5th element]

I suppose a bit more explanation to how I do this would probably be helpful.

The first thing I do is take the loudspeaker and clamp it, by the magnet, in a vice. The second is to attach a 6mm piece of MDF to the topside of the driver with bolts through the drivers mounting holes. The piece of MDF should overhang the size of the drivers frame by a few mm, say 5-10mm. You will of course need to countersink the bolt heads into the MDF so that they do not protrude up at all from the MDF itself. To keep the piece of MDF away from the driver itself you can use standoff/separators like these.



You then take the router and lay it on top of the piece of MDF and use one of these bits.



And use it to follow around the faceplate/frame/basket of the driver. This will create a template of the drivers frame out of MDF.

Now you remove the MDF template and put the drivers back somewhere safe and dust free. The template can now be used with the inlay kit posted above to create flush mount outlines that you can use to flush mount the drivers and is what I used to flush mount these.





So as you can see the method works rather well.

[BobEllis]

Ahh, a much better method of creating the template than I had seen previously. Thanks, Matt.

The TL tweeters are actually pretty easy, since the corner radius is 1/4", all I need is an 106 x 130 mm rectangle and a 1/2" pattern bit. Hmm - 7 mm radius is 9/16" diameter, and yes, there are 9/16" bits available...

[JonMarsh]

For those who want to be lazy, it could be noted that the worst kind of driver not to flush mount is a round baffle faceplate, as the diffraction step energy is concentrated at one dimension/frequency. Rectangular, like the TL tweeters, is the most benign, as the diffraction refection is spread out over a wider frequency range, and hence the effect is less noticeable.

OTOH, I do agree with Matt's guidelines, and you may note what I did even with the original Ardent, though a PITA it was....

[Renron]

5th Element,
Nice, 12MU should make a great mid in the Ardent. Makes me more confident in my choice that both You and Bob Ellis think highly of this driver. I'm excited just 'cause it looks cool!
Thank you for (probably) re posting that link to your wonderful and very descriptive guide. It helps a whole bunch, I doubt I would have ever figured that out on my own.
Great directions that are easy to understand and follow. Thanks. That baffle on the dog eared speaker is a thing of beauty! Very nice. Good tips on making templates too.
Vertical lobeing is something I never thought about before. This would explain why MTMs on their sides make poor center channels. (usually)

"For those who want to be lazy", Bob, I do believe you have just been taken to the wood shed.
OT. Bob, have you started on the Honey Badger yet?

I changed my mind and am having Solen ship the drivers that they have on hand.

Ron

[BobEllis]

The urge to have a pile of drivers waiting to be used is strong.

I wasn't going to be totally lazy, there is going to be felt under the grille with a non round opening. Not to mention that my Honey Badger has been in use for a year or so. Can't say as much for my Aleph-J clone and F5T that are in various states of final assembly.

I haven't worked with the 12MU, I was going on Jon's recommendation as the one to use if not going C79.

[5th element]

I haven't used the 12MU either as per say, I am a very strong believer in the 'measurements tell pretty much the whole story', kinda guy, if you know how to interpret them correctly. I have not been let down by this philosophy so far and if anything it just forces you to learn, especially in this hobby where you don't really have the funds to buy and test every driver under the sun (unlike some *cough Jon Marsh cough*), you really need to get good at driver selection before you buy.

The 12MU is a very nice driver and doesn't exhibit most of what you'd typically expect of a soft coned driver, with the revised edition, as measured by Vance, being even better. It has a nice sensitivity, granted it isn't super high, but it's a step above most of the competition, especially for such a small driver, it has a nice controlled cone with zero metal cone type artefacts, it's breakup should be a cinch to control in the stop band if required and it has excellent harmonic distortion. 3rd order is at or better than -60dB for the drive level Zaph measured at with the high harmonics being exceptionally well controlled. The 2nd harmonic is at -50dB or better for a wide portion of its passband, which is nice, all apart from that small blip in 2nd HD at around 1.5kHz. The drivers small diameter is also a huge plus along with its cosmetically and functionally pleasing motor and basket design.

Most of the Illuminator midbass drivers have failed to impress me in any way with the old Revelators actually having superior measured performance. The only thing that some of the Illuminators have is excellent capabilities down low if you wish to use the 6.5" drivers as dedicated bass units in a three way, but they are incredibly expensive to be used in such a way. You could quite easily go RS225, get a larger SD (and greater sensitivity) and thus lower bass distortion as a result, or go the route Jon did and use something like the Wavecor subs.

Of course a lot of this is nitpicking as most of scans boutique drivers are all of an easily passable standard and will make glorious music, but then again what is the point of this hobby if we cannot cherry pick the drivers specifically to get the most out of the projects we embark on? Jon's Ardent is a nice example of design evolution where a decent start ended up as something considerably more capable.

As you've decided to go with the 12MU another midrange that would be worth considering is the TangBand 75-1558SE. This is another one of those stand out products from a more mundane line up of products. Absolutely excellent HD with a nicely controlled frequency response. As Zaph says it does need a somewhat low xover point due to the size of its flange, but I don't see this as too much of a problem as there are lots of capable tweeters out there. There are far too many drivers out there that I'd like to use but not enough time/money/need for loudspeakers to make them actually justifiable and lots of them are mid range drivers too and that makes things even harder where simple two ways are more suitable 99% of the time.

[benchtester]

I haven't used the 12MU either as per say, I am a very strong believer in the 'measurements tell pretty much the whole story', kinda guy,...

I am throwing this up for those who like to contemplate the charts and to respect the "poor man" requirement. The Scan-Speak 10F looks competitive with the 12MU at a much lower price. Zaph has measurements of both the 10F (10F/4424G00) and the 12MU (12MU8731T-00) in his blog:

http://www.zaphaudio.com/blog.html

Erin also has tested both using Klippel:

http://medleysmusings.com/scan-speak-10f4424g00-discovery-4-midrange-4-ohm-version/

http://medleysmusings.com/scan-speak-illuminator-12mu4731t-00/

Admittedly, the 12MU looks better than the 10F in Erin's graphs. But the FR and HD charts from Zaph make me think that subjective experience would be equivalent.

What does everyone else think?

[Renron]

Zaph tested the 8 Ohm version. The 4 Ohm's frequency response is smoother. I've posted the 4 ohm version's graph previously. I was trying to get performance as close to the Accuton c79 without the $$$.
Agreed, time to get back to the "poor man's version".

[5th element]

Well if you're trying to replicate the Accuton on the cheap then you need two things - low distortion, a rigid cone and completely resonance free operation within its passband. The budget version has been blown out of the water imo. A budget version would be RS225s, the ZA14 and DXT tweeter from SEAS or one of SEAS prestige tweeters without the waveguide if you like.

The 12MU and 6600 will sound fantastic though

[Renron]

Yea, the budget is toast. Mission creep and upgrade-itis did the budget Ardent in. Thanks for the tips for others still on the budget mission/path.

Could someone please clarify the thickness of the baffle? 3 3/4" ? (5@3/4") or 4 1/2" (6@3/4") ?
at ~$50 a 12"x60" BLB more than one per baffle adds up quickly.

Dar47, Benthe8track mentioned that he could not discern any audible differences between the materials you built your armada of Ardents out of. Could you hear the differences?
Ron

Any pictures of a Dark wood Ardent?

[5th element]

Well personally when one is going to put so much effort into making the elaborate cabinet of the Ardent that you should at least fit it with drivers of a certain quality. Proof of concept, with lesser drivers, is always valuable, but it's not like Jon hasn't already done this.

[dar47]

This depends what your material stock is, first you need a minimum ( Ardent baffle designed to), 2 layers of 3/4" bamboo and 2 layers of 18mm (or 3/4") BB. This is to facilitate the 40 deg. facet. If your buying 4' x 8' sheets as we did it would make sense to do 4 layers or bamboo. If your purchasing 1' boards then 2 layers of bamboo brings you to spec. Nothing wrong with 1 layer of bamboo & 3 BB, you still have 1 ridged surface for mounting drivers. If your poor but not the poorest you can do 4 layers of BB. The poorest of the poor can do 4 layers of 3/4" MDF. or total 3". :W

Ben has his Walnut burl Ardents up and running but they are in a dark basement and he hasn't had time too take great shots yet.

[BobEllis]

Ron, somewhere in the Ardent thread are some shots of a cool walnut burl.

I'm going with 4 layers of bamboo on my good baffles, for a total of 3" Since I can't see how to get facets wider than 3.5" with a table saw, that is plenty of depth. Unless I go for the router method mentioned earlier.

Matt, the work involved in the cabinet was the main driver behind my mission creep. The poor man's version is going to serve as woodworking warm-up since I haven't done any in a while. It will be a nice addition to the summer home, which is rather rustic so if the workmanship isn't the best, it's OK.

[dar47]

Great plan Bob. :T:T

I'm a prototype guy too, and my keepers are usually 2nd builds. Keep in mind when you have put in some 300+ hours the material starts to look cheap.

[benthe8track]

Yea, the budget is toast. Mission creep and upgrade-itis did the budget Ardent in. Thanks for the tips for others still on the budget mission/path.

Could someone please clarify the thickness of the baffle? 3 3/4" ? (5@3/4") or 4 1/2" (6@3/4") ?
at ~$50 a 12"x60" BLB more than one per baffle adds up quickly.

Dar47, Benthe8track mentioned that he could not discern any audible differences between the materials you built your armada of Ardents out of. Could you hear the differences?
Ron

Any pictures of a Dark wood Ardent?

Just to clarify; I speculated that I may not be able to hear the difference between the materials used in ours and ones made of MDF. I haven't actually heard a version made from MDF

I'll dig out my flash and try to take a decent picture this week. In addition to hideous wood paneling and carpet the basement of the house I'm renting has terrible lighting in the basement.

But these are what they look like more or less:

[Renron]

Benthe8track,
I apologize for misquoting what you had said. Sorry. It was not my intention to mislead. Your speaker looks fantastic, even next to that carpet. I was trying to find some pictures of the finished product in a dark wood to show my wife. A good quality photo would be appreciated.
We're thinking about Bubinga veneer.

Thanks for all of the answers to questions which I'm sure have been asked at some point previously. Very nice folks on this forum.

[JonMarsh]

Arguable.

Jon used the materials he did because he thinks the benefits justify the additional cost, as he's discussed several places. But, I can guarantee you that if you post this question on three other forums, you'll get a much larger response that at 3" thick it doesn't matter what material you use than you will of people supporting the Bamboo LBL Jon used. I can also guarantee you'll have people arguing that 3" of anything is overkill. I've found people who preach using steel angle bracing and concrete walls as well as people preaching braced 1/2" ply. And on the internet they, they all sound like experts.

To each their own. ... I think this is where years and years of speaker building comes in handy. After all those years, you realize what is and isn't important to you as an individual. Some people find the stiff overkill box as their nirvanna, others open baffle speakers, others folded horns. Some people like the woodworking aspect and build complicated boxes just to challenge/improve those skills. Others find themselves to be better rough carpenters than finish carpenters and gladly accepts any slight knock on the potential sound quality impact just to get the project done (I include myself in the latter). Your truth is out there, but you got to build to find it.

Wow.... how's that for an answer!

That's a great answer, Ryan! Nails it pretty much. The only point I might add is possibly to steer clear of people who say something isn't necessary or is overkill, but haven't actually tried it themselves... sometimes folks don't know what they don't know.... :W

[Renron]

The urge to have a pile of drivers waiting to be used is strong.

Channeling Evil Twin?

[JonMarsh]

Channeling Evil Twin?

Sounds like it to me... :W :B

[JonMarsh]

Ben hasn't been very cooperative with providing nice pictures of his speakers, :W but these in process pics after the first pass on finishing isn't bad at conveying what to expect with a dark veneer like walnut burl.





And below, an Avalon Time with a similar finish, in satin.



White balance in color rendering is tricky if you take pictures under various types of artificial lighting, and Ben's pic above has a strong yellow cast likely due to that- either warm fluorescent or incandescent, with the camera set to daylight or shade.

[kevinm]

I bet one of these would be gorgeous in some nice walnut

[Renron]

Those are Friiiiiikkkkkkkiiiiiiiin Aweeesum !
Thanks Doc!

Ben those are beautiful, I am impressed!

Ron

[5th element]

Imo, where multiple materials are being considered for a build, and if layered building is going to happen, then using all three is probably the best idea. This is especially true if the materials are of 'similar' construction, ie in this case all similar-ish densities and wood based or composites there of. I'd be inclined to use the material that machines the nicest, or has the greatest impact resistance for the outer layer, followed by the 'softest' material for the inner layer and then with whatever remains on the inside.

I'd have thought that LBL would be excellent for the outer layer, followed by MDF on the inner core and then ply last.

[Winter]

Imo, where multiple materials are being considered for a build, and if layered building is going to happen, then using all three is probably the best idea. This is especially true if the materials are of 'similar' construction, ie in this case all similar-ish densities and wood based or composites there of. I'd be inclined to use the material that machines the nicest, or has the greatest impact resistance for the outer layer, followed by the 'softest' material for the inner layer and then with whatever remains on the inside.

I'd have thought that LBL would be excellent for the outer layer, followed by MDF on the inner core and then ply last.

Y'all's choice. Jon Marsh has the right idea with the multiple LBL layers. Stiffer and much better damped. Baltic Birch Plywood and MDF have very little internal damping. Even though Baltic Birch Plywood has twice the stiffness of MDF, the baffle cumulative spectrum decay plots for the two look very similar. The Baltic Birch Plywood does not settle any quicker either. The additional hardness of the LBL will also help.

Material............................Stiffness (Modulus of E)...Damping Factor
Laminated Bamboo Lumber....1.5 Mpsi.............................0.2 (good damping)
Baltic Birch Plywood..............1.1 Mpsi.............................0.04 (little damping)
MDF....................................0.45 Mpsi...........................0.02 (little damping)

[benthe8track]

Ben hasn't been very cooperative with providing nice pictures of his speakers, :W but these in process pics after the first pass on finishing isn't bad at conveying what to expect with a dark veneer like walnut burl.

White balance in color rendering is tricky if you take pictures under various types of artificial lighting, and Ben's pic above has a strong yellow cast likely due to that- either warm fluorescent or incandescent, with the camera set to daylight or shade.

Ok ok, I'll give it another shot this week when I'm back in town. :P

[---k---]

Y'all's choice. Jon Marsh has the right idea with the multiple LBL layers. Stiffer and much better damped. Baltic Birch Plywood and MDF have very little internal damping. Even though Baltic Birch Plywood has twice the stiffness of MDF, the baffle cumulative spectrum decay plots for the two look very similar. The Baltic Birch Plywood does not settle any quicker either. The additional hardness of the LBL will also help.

Material............................Stiffness (Modulus of E)...Damping Factor
Laminated Bamboo Lumber....1.5 Mpsi.............................0.2 (good damping)
Baltic Birch Plywood..............1.1 Mpsi.............................0.04 (little damping)
MDF....................................0.45 Mpsi...........................0.02 (little damping)

I'd be interested in having in my files the original reference that you pulled those numbers from. I got wood books that have E for lumber, but not ply. And nothing that has dampening factor.

[Winter]

I've been collecting the data from numerous sources. The specifications usually vary approximately by 10 or 15%, sometimes more. Some data is found under construction materials, wood products, etc. I spent a lot of time Googling. Here's one link.

PDF not available

Damping factor for a material may be listed several ways:
damping factor = loss factor = 1/Q = tan delta = 2 x damping ratio

Here's two links for damping factors:

http://audioqualia.prophpbb.com/topic29.html

mech300_7_1_damping_ref.pdf

[---k---]

Interesting. Thanks. I'm going to have to look into that further.

[Renron]

Sunday bump

The Driver fairy stopped by last week, aka the UPS driver. He brought me 2 packages one of which he used his hand truck for, ( I have a long steep driveway)
The smaller (and lighter) of the two, contained the Air-Circ tweeters and the 12MU/473100 mid drivers from Scan Speak
The hernia inducing box contained 3 of the 4 Wavecor SW223BD01 sub woofers I had ordered, Solen only had 3 in stock. I'm not planning on starting the build for a while anyway.
What surprised me is the weight of the Wavecor driver, This thing is built like a tank with a huge magnet hanging off the back. Underhung drivers just look cool. Same with the 12MU.

Jon, er....Doc maybe even E.T. , is that offer still available to send you one of the 12MU for testing? That would be great, as I'm still in the Red-Neck driver testing laboratory myself. I could not resist just trying it out! It sounded great btw in a 5 gallon bucket! Should have been flush mounted. LOL .
Nude driver shots follow.

[BobEllis]

I'm going to have to do similar testing with my C90s soon to at least verify basic operation.

Also, I'm a bit too scared to try Matt's template making with the C90, but then there is this to allow me to make a template and keep the drivers dust free. Mounting plate for the cell driver, appears to be identical shape as the C90 faceplate. Not cheap, but I feel a lot more comfortable.

[JonMarsh]

That's a good idea, Bob. I had a C90/79 that was damaged, and used it as a template for creating rebate tooling.

[JonMarsh]

The Driver fairy stopped by last week, aka the UPS driver. He brought me 2 packages one of which he used his hand truck for, ( I have a long steep driveway)
The smaller (and lighter) of the two, contained the Air-Circ tweeters and the 12MU/473100 mid drivers from Scan Speak
The hernia inducing box contained 3 of the 4 Wavecor SW223BD01 sub woofers I had ordered, Solen only had 3 in stock. I'm not planning on starting the build for a while anyway.
What surprised me is the weight of the Wavecor driver, This thing is built like a tank with a huge magnet hanging off the back. Underhung drivers just look cool. Same with the 12MU.

Jon, er....Doc maybe even E.T. , is that offer still available to send you one of the 12MU for testing? That would be great, as I'm still in the Red-Neck driver testing laboratory myself. I could not resist just trying it out! It sounded great btw in a 5 gallon bucket! Should have been flush mounted. LOL .
Nude driver shots follow.
[ATTACH=CONFIG]23883[/ATTACH][ATTACH=CONFIG]23884[/ATTACH][ATTACH=CONFIG]23885[/ATTACH]

Isn't it great when the Driver Fairy delivers the goods? :B

The offer still stands for doing the measurements- I think that's the safest way to go.

We're in the final stages of getting packed up for our trip to way down under- Argentina Aerolineas through us a curve ball and cancelled the connecting flight we have from Buenos Aires to Ushuaia, and initially putting us on one that departs Buenos Aires 2-1/2 hours before we actually arrive in Buenos Aires! GF got that sorted out, but had to use her Spanish quite a bit, and talk to Argentina Aerolineas directly as the folks at Kayak said the English language phone connection was down over the weekend- and we didn't want to wait until Monday to begin working on this, as a check online showed not very many seats available on other possible flights.

I'll let you know when we're back after the middle of March- we're pretty much incommunicado, as the ship has communications available but only at truly breathtaking cost... I'm even bringing my own personal cloud of sorts, a 2TB driver which has an SD card slot for uploading photographs, and wireless for connecting to Macs/PCs and mobile devices- I'll be able to bring shows and media and only download them from the drive as needed, and use the drive to backup all the photos.

[---k---]

Jon,
Unplug, relax. We'll be here when you get back. Looking forward to seeing the pictures and hearing the stories.