A new home for the BG ribbons?

[JonMarsh]

If you did it that way, it would be hard to decide if it was a dipole or an IB! h:

Seriously, a lot of the benefit of the diopole is less room interaction due to cancellation at the sides. The situation you describe could work fine, but it would be more like an IB setup, it seems to me. As long as there wasn't stuff along the wall to reflect/diffract the sound, it might work fine.




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[JonMarsh]

Hank scooped the CSS T/S parameters for those interested.

It's a relatively low Q driver, Qts ~ 0.36, and the Fs is speced at 48 Hz. With a 20 gram cone (fairly high mass for a 6-1/2), it will work well in a small volume (12-16 liters), but you have to tune below resonance, and it tends towards a saddle shaped response, with not really a speak at the low end tuning, but a fairly high Q Qb4 alignment and roll off. Because of the Q and cone mass, output in the 50 - 120 Hz area is down almost 3 dB from midband. This may be compensated by the relatively high voice coil inductance of 1.4 mH. This would be a fairly "punchy" driver in a relatively small box. If you wanted to do the line source flat to 50 Hz (and die quickly below that), with minimum volume say 10-12 liters, this would be your part.

A 12 liter box with 46 Hz Fb gives over 100 dB down to 45 Hz, dying quickly below that.

A 16 liter box has to be tuned down to 36-38 Hz to avoid peaking, and this results in a drop in the maximum output level between 50 and 60 Hz of 2-3 dB. It will have strong output down to about 32.

Note that the predicted midbass (50 - 120 Hz) reference efficiency for the CSS driver is about 94 dB/10 watts. For the MCM, it's 98 dB/10 watts. This is largely due to the difference in cone mass, which is almost 2 to 1. But it's why the CSS can go moderately deep in a very small volume. Hoffman's iron law again.

If you want the absolute smallest line array, (using a 6-1/2" driver), this is a good choice.

-Johann




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[PMazz]

Hank,
Well, I wasn't in a hurry to start the project beyond working most of the kinks out. Every time I think about these, I seem to change direction. I'm still tempted by the Styke drivers, as I am still leaning toward a sealed alignment, however the Stryke, as Jon said, are really only good for sealed vs ported. If I should find later on that I need to port them for more LF help, I'd be stuck. I may after all just get the Peerless 6.5", as they would work well both ways.

Business has been slow. A good and a bad thing, as time is abundant, but not money. Funding for this project may have to be of the plastic variety, as cash flow is really drained. I'd be looking at $1500 in drivers alone. Man, this is really killing me! Normally I'd do this in a heartbeat.

What's your idea for the angles?

Pete

[Hank]

What's your idea for the angles?

Pete, do you mean how would I veneer the angled edge, OR, what degree angle would I use? If you're asking about veneering, I'd have to cut the veneer off at the edge and maybe glue a solid piece of the same hardwood to the flat edge and then round over the hardwood edge. I'd like to use my new big 1 1/4" radius roundover bit for max radius. If you're talking baffle side angle degree, it depends on the height of the cabinet. Seems like Jon is suggesting a 16" wide baffle, so assuming that's the maximum width at the bottom of the cabinet, and if the width at the top of the baffle is say, 12", then the angle would be determined by total cabinet height.

Looks like Danny designed a decent driver for his line source. But, it's a good bit more expensive than the MCM. How much wider/deeper would a cabinet for the MCMs be than for the CSSs?

[JonMarsh]

Looks like Danny designed a decent driver for his line source. But, it's a good bit more expensive than the MCM. How much wider/deeper would a cabinet for the MCMs be than for the CSSs?

For the same LF cutoff, with the MCM's the enclosure volume will be about 40-50% larger- say, 12 liters for the CSS versus 16 liters for the MCM. The MCM is 2 dB more sensitive in the overall midbass. (that correlates with an amplifier power difference of about ~55% coincidentally- so the MCM's would play to the same volume with 10 watts that the CSS would require 15-16 watts.

This is probably not a big factor, though it means the MCM's might have measurably less thermal compress (due to voice coil heating) at the high end of the scale. I doubt that you'd actually hear and notice it in real use.

If you can get the CSS at a good price from Danny, I can see that being an attractive solution. Do you know what the net internal volume for the woofer chamber for the nine CSS drivers was in AlphaLS?

BTW, the distance across the flats on the MCM is 6-3/8" in case anyone is curious.

With any of these six's, back radiusing the woofer cutout will be desirable to reduce/avoid blocking the rearwave exit area.

Regards,

Johann




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[JonMarsh]

Active Crossover Possibilities

Marchand has just introduced a new "passive" active crossover module. It's available as a standalone module to incorporate in other gear, or in its own chasis with level controls.








Steep 24 dB/octave 4-th order slope (Linkwitz-Riley) standard. Other slopes optional.
Asymmectric or symmetric slopes.
Crossover frequency 50Hz - 20 KHz.
Typical impedance 1KOhm
Uses high quality ferrite pot cores and polypropylene capcitors.
Needs no power supply.
Low Distortion(0.01% @ 1VRMS).
Very high signal-to-noise ratio.
Dimension 3.2" x 4.5" x 1.3"


The XM46 has a single channel crossover network on a single circuit board. The high quality of components is responsible for a very good sound quality. Because of the passive design the signal-to-noise ratio is very high. The noise generated by the crossover is much lover than for the electronic crossovers. The use of large ferrite pot-cores for the inductors is responsible for the low harmonic distortion levels. The circuit needs no power supply and is ideal for incorporating into other equipment, like power amplifiers, etc. We can also provide these crossovers assembled into a cabinet, with or without output level attenuators.


SPECIFICATIONS:
Frequency response: DC to 100 Khz, +/- 1 dB
Crossover frequency: 50Hz - 20KHz
Insertion gain: -1 dB
Filter slope: 24 dB/octave standard.
Harmonic distortion at 1 KHz: Less than 0.01%
Signal-to-noise ratio: Much better than 110 dB
Input impedance: 1K Typ.
Output load capability: 10 KOhm min.
Maximum input voltage: 10 V RMS
Dimensions: 3.2" x 4.5" x 1.3"
Shipping weight: approx. 1 pounds (.5 Kg)
ORDERING INFORMATION:
XM46-A......Passive crossover board, assembled.
XM46-K......Kit.
XM46-AA.....Passive crossover in cabinet w. level controls, assembled, stereo.
XM46-EZK....EZ Kit.
XM46-KK.....Kit.
When ordering please specify the crossover frequency.
We have frequencies from 50Hz to 20KHz available.

http://www.marchandelec.com/

This will NOT work with a passive preamp, as it requires a low source driving impedance, and presents a load to the preamp of about 1 K ohm. :?

This is necessary in order to have low value terminating resistors for the pasive network, and relative insensitivity to the amplifier load impedance. It also helps if you have to drive short runs of cables.


What's intriguing to me is the possibility of combining this with some of my non-loop feedback class A transconductance modules, and incorporating any shelving EQ for baffle step or other issues in the output load of the transconductance amp. (this design uses a heavy class A output stage, which is actually current output, and develops a voltage output by means of the low value load resistor termination. If you add additional R/C or gyrator networks, then shelving or notch EQ can be added easily, while retaining a very minimalist signal path- full complementary JFET+bipolar class A, DC coupled, no loop feedback.

Even the standard Marchand version sounds pretty interesting to me.

Regards,

Jon




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[Brian Bunge]

Jon,

I'm currently building 3 pairs of the Alphas for a local customer. Working with the internal dimensions and subtracting for the tweeter enclosure and bracing I'm getting roughly 4.75ft^3 (around 134L). Of course, I didn't factor in the displacement of the 4 dual flared 3" ports. I believe their end to end length is around 7.25".

Brian

[JonMarsh]

That sounds about right for the enclosure volume based on my individual driver analysis, assuming LF tuned for response down to about 45 Hz. Is this from the kit plans from GR research?

I'm taking my laptop to England after the next two weeks of business travel, and I'm going to gin up a plan for an enclosure for 8 of the MCM's with a BG RD50 ribbon, not the Neo8's. The RD50 will need more rear chamber volume, due to the crossover point and resonant frequency, etc. I expect I'll crossover around 600-700, depending. I may try both a standard 4th order L-R as well as my cauer-elliptic 48 dB/octave slope crossover, since there aren't any more parts in the forward signal path for that compared with the 4th order L-R. I'm going to "tune" the baffle size to put the diffraction step frequency at the crossover, so as to simplify the network if I go passive. I'm expecting to use about 24 liters for each six, so that will be about 200 liters for the midwoofs alone.

How do you plan on finishing the cabinets? Hank's certainly looked pretty nice in the posted pictures; I expect I'll do more head scratching over the wood working than the actual speaker design- I've done some "pretty" stuff in the past, but I mean the "PAST", as in early to mid 70's!

Keep us posted if you can on your progress!

-Jon




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[Brian Bunge]

Jon,

Yes that was from using the plans from Danny. The three pair I'm building are going to be raw MDF with 1/2" rounded edges. I moved the tweeter line over towards the woofers about 1/8" thinking that I might be able to use my 3/4" radius bit but it still looks pretty tight so I might just stick with 1/2". I can't afford to ruin the cabinet trying to experiment.

We're also building a separate pair for him that we'll be veneering for his 2-channel music system. It will probably be maple with red mahogany dye similar to the cabinets seen here:

http://www.rutledgeaudiodesign.com/AV1+_side_2.jpg

Then he's designing some line arrays himself using some Neo8's and some woofers yet to be determined for a for a friend of his. He's building the center using 2 Neo8's and whatever woofers he chooses. Then we'll build the other 4 cabinets to his specs.

I'm hoping it'll help drum up some business for us since it's possible that I may not have a job after mid-October.

Brian

[JonMarsh]

That's a pretty sharp looking cabinet, Brian!

Yeah, the employment situation for a lot of folks these days is less than stellar. The company I work for is sort of schizophrenic, being a diversified semiconductor company. Several of the big divisions are in the toilet sales wise, and look to remain there for a while- it's draggin down the division I'm in (power semiconductors) which is growing in a declining market by taking market share away from some of the established folks due to a combination of advanced component and manufacturing technology and very competitive pricing. But our group is starved for resource, and the promised added tech guy is undergoing review again in the home office in Germany; I give it 50:50 odds. We had about 8% layoffs last fall, including our group admin and some of the tactical marketing people. This in spite of our group hitting it's growth targets.

I hope things turn out for you better than you expect, but part of why I'm ginning up on the DIY is the possibility of needing to do something generating income other than my "normal" job- and I don't want another job that I don't like.

But right now it's just exploring designs and having some fun- nothing for money, tricks for free.

Best regards,

Jon




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[Brian Bunge]

Thanks Jon! That's a GR Research A/V-1+ cabinet. My dad and I are supplying cabinets for the A/V-1 and A/V-1+'s. The need for income is part of why Hank and I were looking into a narrow line array on top of a bass cabinet (a la the Soundline stuff). While I understand the drawbacks, we were sort of hoping for "good enough" for the masses. If it could be sold for say $2K/pair that might be cheap enough for someone to consider them over a standard 2 way monitor or tower in the same price range. Of course, this assumes dirt cheap quality drivers which are few and far between.

Brian

[Hank]

For the same LF cutoff, with the MCM's the enclosure volume will be about 40-50% larger- say, 12 liters for the CSS versus 16 liters for the MCM.
If you can get the CSS at a good price from Danny, I can see that being an attractive solution. Do you know what the net internal volume for the woofer chamber for the nine CSS drivers was in AlphaLS?

With any of these six's, back radiusing the woofer cutout will be desirable to reduce/avoid blocking the rearwave exit area.

To me, that 40 - 50% enclosure volume difference is very significant, UNLESS it only helps depth-wise, which I suspect will be your answer. I could ask Danny for a discount, but he'd probably want more than one or two guys' business for that (my guess). But, if either driver requires the same baffle width, I'll go with the less expensive MCM.
Yes, I back-radiused the woofer cutouts in the Alpha LS cabinets - a necessary detail.
Brian: re-check the port length.

[Hank]

The need for income is part of why Hank and I were looking into a narrow line array on top of a bass cabinet (a la the Soundline stuff). While I understand the drawbacks, we were sort of hoping for "good enough" for the masses. If it could be sold for say $2K/pair that might be cheap enough for someone to consider them over a standard 2 way monitor or tower in the same price range.

Jon, that's right. My original idea was a narrow line source and separate detachable sub module. Such an implementation would allow detaching the line source and installing them as in-walls and "hiding" the sub module (allows for extremely serious WAF effects). I wanted to do the line source with TB 2" or 3" drivers.
How I got from that point to buying RD50's and stacks of 6.5" drivers is sort of a blur...

Have a good trip!

[Brian Bunge]

Hank,

I radiused the back of the woofer cutouts too. BTW, are you asking me to recheck the port length or telling me to? In other words, do you think I'm wrong or simply asking because you want to know for sure? I don't have the plans in front of me (just your cut list) so I'm strictly going by memory.

Brian

[Hank]

Brian I was telling, respectfully, of course. My memory may be wrong (no age comments, please ), but I'm thinking the port tubes were shorter than that. So you're going to take off work next week and build Alpha cabinets, eh? Don't hurt your back.

[Brian Bunge]

Hank,

I'll double check. The good thing is that there's so much port tube left that we can always cut another center section if we're wrong.

We'll be building Alphas, a pair of Criterions, 3 A/V-1+'s with 45 degree mitered joints and more of Danny's demo cabinets. Lots of work to do!!!

Brian

[JonMarsh]

To me, that 40 - 50% enclosure volume difference is very significant, UNLESS it only helps depth-wise, which I suspect will be your answer.

Gee, Hank, once you can read my mind reliably, we won't have to post back and forth anymore, will we? :LOL:

It comes down to desired LF extension versus size (depth especially). I'm going to calculate a front baffle size that will put the baffle step at the chosen crossover point, so that only the woofer would have to be EQ'd if a passive crossover is used.

The orignal AlphaLS design has a crossover up around 1100-1300, right? So baffle step compensation is inherently only going to be an issue for the woofer.


Taking a look at this with Baffle Diffraction Simulator (by Paul Verdone), my take on it is that a 15" wide baffle is OK for a crossover at 600 Hz based on the above criteria.

A simplified view of the layout, which is limited by BDS to four drivers for a line source evaluation, is below- this is a 15" wide baffle.




Looking at the summed driver group ressponse and radiation gain,



this predicts the peak in the baffle step and subsequent roll off at 600-800 Hz. It could be feasible to further reduce the baffle size, but you'll have trouble mounting them in anything less than 13", particularly if you want to do round overs on the baffle edges. I figure a 15" wide cabinet with 1" roundovers would work pretty well.

Here's the individual driver response, in case you're curious...




Regards,

Jon




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[PMazz]

Does the RD 75 rear chamber have to be isolated from the woofers? If so according to B&G's spec sheet, for a sealed enclosure, the bigger the better. What size is adequate without overkill?

Pete

[ThomasW]

Pete

Yes the planars should be completely isolated from the rear wave of the woofers.

Look at the Wisdom Audio website for some guidance. Wisdom owned by Tom Bohlender makes the optimal cabs for the B&G planars




theAudioWorx
Klone-Audio

[PMazz]

Is there an advantage to totally seperate enclosures? That may open up some other options.

Pete

[JonMarsh]

One of the points I'm still debating in my mind is whether to make a one piece cabinet or to go with a modular approach. The latter would be heavier overall, but each peice would be lighter and easier to move. The seperation between the RD and the midwoofs in a single cabinet would need to be as stout as main cabinet walls. One construction I'm considering is a combination of baltic birch core and MDF sheath, as that will mill and laminate better. But the combination wouldn't weigh as much as double walled MDF. I"ve already got cabinets built that way- they're hell for stout, but weight similarly- my good ole X1 Klones.

If modular, it would be an RD50 cabinet , fairly slim and deep, a mating midwoofer cabinet with the 6-1/2", then ultimately a line array woofer? Four DPL12's or similar? If I could get more BP1203's, they could make a very small cabinet (due to the T/S parmeters). The latter doesn't have to be that physically close.

The crazy thing is, there are so many intersting possible configurations; most of them could work pretty well, with reasonable development. The smallest dipole configuration I'd consider would be an RD50 with four M8a drivers. Six would be better though; wire two drivers in parallel for three sets, then parallel these three sets.

Until I move, sub will probably be built from the two BPD1203s I have on hand; one for each channel. Mini-Me's, as it were, next to Thomas's IB's.

-Johann




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[Pat]

Guys, this thread is great!
It got me thinking...how would you do a center channel setup?
Assuming someone had enough cash and time to build 5 of these beasts (not me...unless I win the lottery ).
You really don't want to lay one of those ribbons on it's side do you?




Pat's Page

[PMazz]

Yea Jon, as a modular setup we could do the seperate ribbon with a simple bass box, and if that didn't work build a line of the 6.5s. What does that do to controlling baffle step tho?

I was thinking one of those adjustable electronic xovers that Marchand sells would be fun for trying different xover freqs too. What do you think of those? They certainly seem convenient, although you'd lose the abilty, I think, of inserting other filters like the 44 has.

Pete

[Dennis H]

Ah, centers. There aren't any good answers. Possibilities...

Build a substandard center. I don't think so. I hate dinky little centers and think they do more harm than good to the soundstage.

Build a single identical (or pretty close) center. That would be okay if you had a front projector with a perf screen. You'd probably get some comb filtering off the screen but hopefully it wouldn't be too bad. And, of course, for an audio-only system, that would be ideal.

Run a phantom center. That would probably be the best choice for most people with average size rooms. Keep the mains pretty close together and forget the center.

Run two centers on each side of the screen. That would be my choice for a big room and a small TV. The centers would be close enough together that comb filtering wouldn't be that big a deal, especially compared to the comb filtering from a pure stereo system with wider spaced speakers. I never hear anyone complaining about their stereo systems comb filtering when a vocalist is stage center so I think it's an overblown fear.

[JonMarsh]

PMazz,

The XM6 from Marchand is a great development tool, but it's not a casual investment. ThomasW has one, and it's come in very handy from time to time. I'd like to get one myself, it's just an ROI/cost-benefit analysis. I have an electronic crossover call the PXO (Parametric (X)CrossOver) which I developed as a prototype for a company I worked for in the late 70's; it is like some Pro crossovers, having a variable crossover frequency control from 100 Hz to 10 kHz (this predates the current concept of subwoofers crossed over below 100 Hz- we're talking 1978, you know and while we had a nice 15" slot loaded sub that was flat to 30 Hz and down 3 dB in room at 25 Hz, this was aimed at a more general purpose Pro market). It has a crossover Q/level control, like the Marchand's have now (both are based on state variable filter topologies), and input and ouput level controls. Updating with a 4th order network and more modern opamps would take a complete rework- it's a question of investing the time in design and assembly, vs. just investing the money in a Marchand. The latter probably makes more sense!

But remember, all the Marchand crossovers can be adjusted in frequency fairly easily, by changing out frequency moduels; for the XM9's, it's just dip 8 assemblies with resistors; for the XM44, it's a bit more complicated!

Re baffle step, if you did a monopole with a 200 Hz crossover to a bass box (you know, Stage 1), then you'll almost certainly have to have baffle step comp built into the RD crossover. Don't worry about estimating it before hand; build it, measure it, compesate it.

The problem is, if you do it passive, it affects all crossover values, so you'll have to toss it if you then pair the RD up with another line sources with 6's for example. That's where active approaches and the flexibilty comes in very handy. I may prototype on active, then build passive at the final.

Dennis,

Centers. Can't live with them, can't live without them. Or can you?

I've pondered the same situation, and while I like centers IF you can provide good tonal matching (on and off axis frequency response), if you have a really wide band, wide dispersion mains, (particularly something like these line source speakers), then I vote (have voted) for Option #3, Phantom center.

I wrestled with that for my X1 Klones, and concluded that since it was impossible to configure a center with the "launch profile" that the big X1's have (I tried, I failed), no conventional center worked best. I use an FPTV setup, but have a homemade custom screen, and perf doesn't work worth warm spit with digital projectors. I also don't really have the room for behind screen speakers.

Maybe someday, if I could afford 9" CRT's, and have an IB room behind the projection wall, then just hang a Maggie 1.6 or similar in the middle behind the screen. Still, there's an awful lot of light that goes through a perf screen. I don't like wasting the light, especially on a CRT. (I'm a DALITE HiPower fan myself).

Maybe pigs will fly, too. (hopefully not in my neighborhood, though!).


-Jon




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[Dennis H]

Jon,

I think it was Michael Green who said "center speakers are for wimps." :LOL:

[Lex]

Speaking of pigs flying, you guys heard about the flying fish? Sturgeons I believe in Fla. 2 or 3 people seriously injured when they took a filet to the chest. Yikes.

Also, they are trying to stop Asian Carp from entering the Great Lakes. Those suckers can fly 20 feet.

So, maybe there are pigs that can fly too.

http://msn.espn.go.com/outdoors/conservation/news/2002/0808/1415673.html

[Hank]

Well...Jon is slowly coming around to a separate slim HF cabinet with the RD50. Also, the baltic birch/MDF combo cabinet construction is the Nortcreek Music recommended construction (I recommend their little $5 cab construction booklet).
Thinking about the two cabinet idea, since the ribbon cabinet and the mid-woof cabinet would need to be adjacent, that doesn't save any space width-wise, and given the ply/MDF sandwich with it's weight reduction vs all-MDF, I might as well make it one cabinet. Would you make the walls with, say, 3/4" baltic birch with a skin of 1/2" or 5/8" MDF?

[PMazz]

I was thinking more in terms of trying different approaches to using the ribbon. One option, and the easiest for me, is to mount the ribbon on a 12" baffle and run it as a dipole using my sub to fill in the bass. My processors sub xover can be set as high as 200 Hz, so it would make a quick and dirty test baffle. From there, I want to try a sealed enclosure ala Wisdom Audio.

At least I would get to actually hear a dipole ribbon, before committing to a stack of woofs and a single enclosure.

Pete

[JonMarsh]

Exactly how to make this up is an interesting question, Hank.

It depends on the use of roundovers, how you lay up the front panel relative to the sides, etc.

With regards to a two peice arrangment, the only rationale is lowering the weight that any one peice has. This makes transport and setup possibly a little easier. Overall foot print is NOT reduced.

But, the total weight could probably be less for a single unit, as the "shared wall" wouldn't have to be essentially doubled.

Using an outer "skin" of 1/2" or 5/8" MDF would provide a nice platform for the veneer, and allow using solid woods at the corners. I think the front would need to be layed up then probably routed flush with the sides with a laminate bit, then a round over? I'll be pondering different ideas, but probably not in detail until I leave on vacation a week from this Friday- won't have time before then! May still go one peice, I'd like to figure out how much it will weigh...

Thomas is planning to order a set of RD50's shortly; he tells me they will be used with an array of 6 M8a's on each side; this is a "baby" system for the family room... :LOL:

We should all have such "babies"!


I'll be staying with the "cheap" approach. It would be fun if we all took slightly different tacks, then we could compare results. I'll probably do some evals with an active crossover before finalizing a passive design, but I'm pretty convinced I'll remain at about a 600 Hz crossover. If I fall into a bucket of money anytime soon, maybe I'll get some Marchand passive line level modules and build a whiz bang active crossover. It could be a test platform for the Aragon mods, but so could a full range passive version.

Hmmm, this sounds like a job for passive outboard crossover modules, then go which ever way my heart leads me....


-Johann




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[Hank]

Flipissimo

This makes transport and setup possibly a little easier. Overall foot print is NOT reduced. But, the total weight could probably be less for a single unit, as the "shared wall" wouldn't have to be essentially doubled.

Using an outer "skin" of 1/2" or 5/8" MDF would provide a nice platform for the veneer, and allow using solid woods at the corners. I think the front would need to be layed up then probably routed flush with the sides with a laminate bit, then a round over?

Hmmm, this sounds like a job for passive outboard crossover modules, then go which ever way my heart leads me....

-Johann

If you veneer, then add a block of same specie solid wood to the edge, and roundover...hmmm...no I don't think so. With the veneer grain running vertical, the angled baffle edge would make the edge wood grain run at an angle to the baffle veneer. At this point I think I'd round over first, then veneer. I'm dying to try my new 1 1/4" radius monster router bit Needs some thought/experimentation.
Yes, an outboard crossover box would be a nice touch no matter what the contents.

[JonMarsh]

Hank,

I keep meaning to ask you and forgetting- where did you get your "monster" roundover bit? What brand, what vendor?

Inquiring minds want to know....


Regards,

Jon




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[PMazz]

Hank, I asked and then forgot about your design. ops:

Depending on which species you want to veneer it in....

I think a subtler, straighter grained veneer might work better. Maybe Honduras mahogany, Anigre or a similar type, quartersawn if you can get it. I know you like the more exotic stuff. :T

You could wrap the veneer right around, and with a subtle grain, would look good with the grain following the angle on the front.

Or maybe....
Do a seam in the veneer at the line of the radius. Probably wrap the veneer around the radius from the side and run the seam on the front.

Or, lay the sheets out at the angle you need to wrap the piece, align the veneer for a nice look at the seam and cut it, butt it together and tape the seam up and treat it as a one piece sheet. The trick, obviously, is to lay it up exactly on the midpoint of the radius when glueing.

Jon,

http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/bt_rndvr.html

I have their oulet store near me and got the 1 1/4" bit for $19. Forstner bits for a buck, too.

Pete

[ThomasW]

What wife/spouse won't love living with this? :B






theAudioWorx
Klone-Audio

[Dennis H]

Dang it, I wanted to flip it...... :LOL:

Try a bevel bit instead of a roundover. It looks more "real" than wrapping the veneer around the corner and I really like the bevelled look. Small roundovers don't do much for diffraction control anyway. Glue solid wood pieces into the MDF corners, sand or route them flush with the MDF, glue on veneer with a wood backer and then bevel the corners with a 45 degree bit. Soften the edges slightly with sandpaper and you're all done.

Speaking of woodworking, how are you guys hiding the "ears" of the RD in a monopole enclosure? I thought getting some 1" black foam, beveling the edges and doing cutouts for all the drivers might look kinda good. Sort of a grill cloth look without the cloth. It might even help with diffraction control.

How are you sealing ends of the RDs? No ears there. Caulk or stuff in weatherstripping?

[PMazz]

Tom, you need a bigger TV! Your wife must be a saint, BTW.

As much as my better half doesn't really mind what I do (cause she loves this shit too) within reason. How are they sounding????

Dennis, my understanding is they get mounted to the back of a 3/4" baffle. Could have it wrong, tho. Come to think of it, how would you get it out of a finished enclosure??? Hmmm.

Pete

[Pat]

Nice Thomas! :T

Now the question is where did you put the whisper klone that was there?

Pete, the Front Projector is in Thomas' other room 8)




Pat's Page

[JonMarsh]

Pete- thanks for the MLCS link! I love buying on the net as opposed to driving around looking for a hardware store with hard to find stuff....


Dennis,

I like your ideas. I may have to sharpen up my AutoCAD render/visualization skills- I don't have any of the fancy add-on programs, but I think I can get something close enough in plain ole ACAD2000.

Thomas-

Yup, one of the advantages of those dipole speakers is being able to work on both sides of the panel. :LOL:


-Johann

PS: I now have six folders with purchased airline tickets for upcoming business travel... yuck! :roll:




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

[Dennis H]

Nice tool site, Pete. Looks like what I call a bevel bit, they call a chamfer bit. Here's another bit that works well with thick wood-backed veneer.

http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/bt_bead.html

I have a small beading bit like that where the seam between the veneer and the corner wood hits very near the corner of the bit. You really have to look closely at that one to realize it's veneer.

[ThomasW]

Pat

The other Whisper is just sitting in the entry hall. I was planning in using RD-75's in the family room, but the real baffle (not the prototype shown) would simply be too big.

I've been spoiled by the HT speaker set up so the plan is to replace the Whisper Klones with a RD-50 and 8" cone line array.

Anyone want a primo pair of Whisper Klones for $2500?

Pete

That's the 'family' room not the HT. It's easier to test out new designs in there than it is to move the ESL/RD-75/leaf tweeter panels

Also no wife, so no WAF :B




theAudioWorx
Klone-Audio

[Pat]

Anyone want a primo pair of Whisper Klones for $2500?

DOH!...If only I was closer and had some cash :evil:




Pat's Page

[Hank]

Jon, my bit source is MLCS: http://www.mlcswoodworking.com
One of their straight bits beat out the high-priced, teflon-coated bits in a Fine Woodworking test a while back.
Here's the roundover bit listing: http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/bt_rndvr.html
Notice the 1 1/2" mother?
BTW, I really like the Merle band clamps they sell - they really help glue up square cornered cabinets: http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/merlclmp.html

Pete, I'll have to think about the veneering job, and I DO love Rosewood! Another stunning veneer with a beautiful 3-D effect is block-mottled makore. I'll have to use it someday - maybe a pair of 2-way monitor cabinets.

Dennis, a matter of personal taste of course, but I definitely don't like the look of chamfered speaker cabinet edges.

Thomas, while I think they're as beautiful as a blonde babe, I don't know ANY wife that would live with those anywhere in her house other than a dedicated HT.

[PMazz]

Tom,
A couple questions about the ribbons as dipoles.

What kind of SPL levels can you achieve without audible straining?

How do the Etons match up sonically?

How far in front of a RPTV do you think they would have to be, to be effective?

Pete

[ThomasW]

Pete

Haven't tested actual SPL's, but the planars certainly play very loud. One of the things the larger B&G planars are noted for is their ability to take a pounding.

The black baffle was designed with the intent of using a 250Hz XO point (I'm currently using 530Hz). So the planar baffle is too wide and the planar is too far from the cones for a good sonic match nearfield. About 8+ ft back they match up well. I'm getting ready to make the next prototype and it will have the planars spaced about 1" from the edge of the cone frames. That will allow a better blend close up.

Trying to get a good read on the accuracy of the blend is problematic because since I only have one channel and no mono switch on the pre-amp. It's impossible to get one dipole baffle to blend with oner channel of Whisper. They have too much of a difference in dispersion characterisitcs. But listing to one channel of stereo sounds pretty good.

The next prototype will be a left side, that way I can approximate a stereo pair.

I'd place them 2'+ in front of a RPTV.

The Etons are pretty good. Not quite as transparent as the M8a's, but certainly good enough for the family room system




theAudioWorx
Klone-Audio

[Hank]

Thomas, on the next itteration, do you plan to continue with the ribbon section of the baffle angled?