e-Lips

[richidoo]

I'm ready to start the next speaker. I thought I would post my progress, since I have to finish it quick for my G2G. So hopefully it won't drag out too much and you guys can follow along.


This is based on the Lotus Group's Granada open baffle speaker. It has received glowing acclaim since debut at CES 2009. It can be very expensive depending on options. It is 3" thick CNCed baffle, veneered, installed and voiced with digital crossover in your house. A beautiful speaker. Some of my feastrex friends heard it and decided to build variations of it for themselves. I think the main intention of Granada was to generate excitement for feastrex drivers in North America, and finally put on a good demo to show what they can really do. The reviews from Valin, Olsher, Harley were exciting, so I wanted a simple version for myself. I already owned the feastrex drivers, so what the hell.

So after taking a long time to decide which route to take for my next speaker, I bought the woofers a couple months ago. Same woofers used in the Granada, they are AE Dipole12. With Qts=.7, they are designed specifically for open baffle use. They can play low without boosting, in theory. I've not even heard them yet - but word is they are superb bass drivers. The motors are absolutely huge, but only 200W rating, designed for dipole...     This is the 15" version, and the 12" uses the same motor. 


The sight of a pile of expensive drivers stacked in the corner guilted me into getting started designing what I wanted to do. A good friend in MA, and fellow ANer "figby," encouraged me to take the OB route since his Feastrex 9" sounds so good in it. I tried an OB a couple years ago, but I didn't know enough to make it work. Actually it really sucked. But I remembered how great the feastrex sounded by itself in that baffle before the woofers were added. Woofer vibration on the unsupported thin MDF baffle ruined everything. I had the Ushers to chase so I chose not to pursue it. Opnlybaffled (Lin)  got my cool peerless woofers. Hey Lin, did you ever use those?

(500th pic in AN gallery!)

After a month of drawing, and about a dozen minor variations on about 5 major themes, I finally ended up with this design:

It uses some golden ratios, ellipses and eyeballing. I like the way it looks. It is called E-Lips, because it is an ellipse duh but also because it will be like electric lips (e-Lips) singing to me in my living room. My son Henry thought of the name, like e-Mail. 

Time to build it...   First I have to cut this ellipse shape somehow. Make donations payable to CNC shop... hehe     I found articles how to draw an ellipse with string and nails. I tried that, but no matter what kind of string I used, even stranded copper wire, it stretched at the middle thus changing the shape. It has to be very flexible at the tips and very inelastic at the width. It just wasn't working this big. Then I looked into mechanical jigs that use tracks and a beam to draw an ellipse. Woodworkers use these to route picture frames and such. But my ratio of length to width prevents using those jigs. I designed my own jig of the same type, but it can only draw one half ellipse at a time, you have to turn it around to finish the other half. I was discouraged by the time it would take to build it and work out the bugs before I could draw the line. There has to be a better way. Just as I was about to start making the jig, I printed something from CAD and noticed that my free CAD program (CADstd) has a feature that lets you print out large plans to scale, using multiple sheets of paper with indexing lines to create a large paper plan. So 15 pages later and an hour of careful taping them together, and now I have this:



Tomorrow I'll transfer the printer ink onto some thin plywood with a hot iron, then cut it out and sand it to the line to make a template. I'll use that to make the final parts in thick ply with jigsaw, template and flush cut router bit. More to come...
Rich

[stereofool]

Great job, Rich  !

The only bad thing is that you are becoming too smart for me to be able to hang out with you, anymore  . Oh yeah, and too damn ambitious, too  .

[StereoNut]

Wow! 

All you DIY guys amaze me!  I have a hard time just opening the baggie inside a new box of corn flakes in the morning without cereal flying all over the place and here's Rich building OB speakers from scratch.

SN

[lonewolfny42]

Heard the Lotus Group's Granada speakers at RMAF...they sounded very good.

Their a large floorstander....big bucks....mostly everyone in the room was enjoying them.

Good luck with your build Rich....

[rollo]

 Looking good there speaker maan. Would it be possible to make the elliptical piece from Spruce ? or maple. ? Rich what tweeter /mid are you using ?
  Nice design. have fun.


charles

[tmazz]

Wow! 

All you DIY guys amaze me!  I have a hard time just opening the baggie inside a new box of corn flakes in the morning without cereal flying all over the place and here's Rich building OB speakers from scratch.

SN

Bill,

You need to dump the cat and get a dog. That way there will always be someone around to clean the floor for you. 

[richidoo]

Hey Charles! Thanks..

It uses a full range driver from 250Hz on up, no tweeter, no crossover except to the bass drivers. The whizzer is big, but sounds pretty smooth. The driver does beam at high frequency and will cut your head off if you get in its path, Shane will need to crawl around on the floor for safety.   That's part of the reason for the significant tilt. It is also time-aligned within .25". Bass drivers are perfectly aligned together for 10 foot distance.

http://www.feastrex.com/

I have the least expensive model, called D5nf. It uses permanent ferrite magnets in a spherical iron circuit, they claim the shape contributes to magnetic efficiency, I don't buy that but it looks cool and is very heavy, combined with extremely light Mms the baffle vibration is negligible. Joe Cohen, the Feastrex importer uses their 2nd from the top model in his demo Granada, with Field Coil motor with ultra high permeable core called parmendur. I think his is the type 2. $$

As for materials, you are right about the stiffness. Maple would be perfect. This is just a prototype made at a reasonable cost for audition. If it works as well as I hope, I will make it again with 1/4" steel plate to mount drivers, with 18mm Baltic birch laminated in front for damping. Their different resonances will cancel each other to make a really dead but still relatively inexpensive baffle. But no CNC until I hear it first. I was gonna do two layers of home depot birch (shit ply) laminated together, but I think I can do it end grain to add a lot of stiffness against the driver motion. I did that on the speaker stands, it came out pretty good.

One thing I will need to think about is the weight of the base. This wood is light. The bass drivers have a large moment and will rock the whole speaker. I will try weights, Maybe that will be good enough but i may have to screw it down to the sub floor. The steel version will have steel base and back support, so it will be pretty heavy. Add lead to taste.  I do have some real baltic birch, I am tempted to use that now, but I think the light stuff on edge will be stuff enough with bracing. We'll see!  I'm assuming I will throw this one in the garbagio eventually, so rather not chuck the BB.

[mdconnelly]

Rich - I'm way impressed and far beyond just a little envious!    

We all wanna be 'just-like-Richidoo' 

[Bigfish8]

Rich:

I am excited about your O.B. Speaker Project and cannot wait to hear them.  I have talked to many folks that have converted to O.B. Speakers and not one of them would go back to a box type speaker.  I considered the O.B. Route seriously last year but decided I needed more audio knowledge and time to pursue that route. 

Congratulations on your choice of designs and good luck as the project proceeds toward completion.

Ken

[richidoo]

Thanks guys. I'm looking forward to seeing and hearing it go. Nothing done yesterday, except a lot of research (between kids sports) on PC XOs.  Back on it today.

[bpape]

The offset OB will sound great as long as you can tame the woofs.  This is what Scott ended up doing but in the end, has 2 outboard subs and just the Lowther in the offset OB.  Makes some sweet music with only a couple of watts.  You do need an external active xover but this also gives you a TON of control.

Bryan

[richidoo]

Thanks Bry. I hope my woofs are tame, being designed for dipole from the begining, and with enough power and DSP they should behave. You are right about active crossover, especially the digital type like DEQX, AudioLense, Acourate. I'm looking at the software crossovers for budget reasons, and to be able to use external DACs. I finally found some free XO software plugins that will work inside Foobar's plugin DSP stack. Foobar is very powerful platform if you use plugins.

What I am trying to figure out is if foobar can only play stored files, or if it can also play streams, like internet radio and line in from the sound card?  Anybody know?
Thanks
Rich

[tmazz]

It is also time-aligned within .25".

Gee, open baffles, time alignment this starting to sound almost like the Dahlquist DQ-10s.

Back to the Future.








Just like with jokes, there's no new ideas in audio, just refinements and updates to old ones. (of course the DQ-10s had a sealed woofer enclosure so the weren't completely OB.)

Jon Dahlquist was a visionary thinker whose ideas  have become the cornerstone of many modern loudspeaker designs.  If I am not mistaken he was the first speaker designer to talk about time alignment (or at least the first one to incorporate it into a commercially produced product.) He also introduced the concept that time alignment is not necessarily a physical alignment of the drives them selves. The sound from each drive emanates from a virtual point of origin (not unlike the focal point of a lens), that could be in front of or behind the physical driver and that the virtual point of origin can move based on the electrical characteristics of the circuits before the drive (i.e the crossover network). And according to Dahlquist it is those virtual points, not the physical drivers themselves that need to be aligned. This explains why so many people who tried to upgrade their DQ-10s with "better" drivers or crossover parts ended up losing that DQ-10 magic.

As for getting some more weight into at least the prototype, The base looks like it could be hollow, can you fill it with sand?

Sounds like you are going down an interesting road with lots of potential. May the force be with you.



Edit 12/28/10 to remove picture from blacklisted domain. Sorry!
Edit 12/29/10 replaced picture with clean gallery version. 

[richidoo]

Wow, those things look cool.... Thanks Tom. I'd heard about them, but never seen those before. Very interesting! Did you ever hear them play?  Not much is new in physics, just the methods evolve.

Base is hollow, so sand or lead.  Probably screws for now.

I was able to transfer the ink from the printed plan to the wood template board today. For some reason I was procrastinating that, never done it before. But now it's done, so we're back to making sawdust. 
Tomorrow I'll get the baffles cut and laminated together, and hopefully all the rest of the parts cut at least.

[tmazz]

So if the bottom is hollow would it be possible to put a piece of plywood across it to close it in so you could fill it with sand and provide some ballast? It's hard to tell from the limited set of drawings in your posts.

As far as DQ-10s go they are the speakers that got me started into the high end nervosa. I think I posted the story about how I bought them on the drive home from my honeymoon. If not let me know and will fill you in. They imaged like mad but were limited by the driver technology available in the mid 70s. Anyway, they were my main system speakers for about 4 years only to be upended by the Thiel 3.5s. I did not realize it at the time but with his Coherent Source designs Jim Thiel really took Dahlquists theories to the next level. While Jim talked about speakers that were both time and phase aligned, I really think that his concept of phase alignment was nothing more than another way of describing Dahlquist's virtual focal point ideas. And of course doing it with much more advanced drivers and cabinet design. I just bought the Thiels because I liked them bast after auditioning many different speakers and it was not until some time later until i made the connection between the two design theories and it all of a sudden made sense why I was drawn to them.They were a speaker that was way ahead of its time. I recently had the opportunity to listen to a set and 35 years later while they are not up to today's state of the art. they can still compete with a lot of what is being sold today. 

Two of the biggest criticisms of the DQ-10 was that they needed a lot of power to drive properly, which they did and they sounded kind of hard in the upper registers. Well looking back I think the second was caused by the first. The designed did suck in a lot of power. Needed at least 200 wpc to make them sing. I heard a big difference when I moved up from a Hafler 220 to a Hafler 500. But I think a lot of the hardness people complained about was due to the sound of the high power SS amps from the early 70s. There really were no big tube amps back then so you were limited to high power SS like Dynaco and Phase Linear which weren't the smoothest sounding electronics in the first place. Upgrading the Hafler 500 to a Moscode 600 amp really smoothed them out. I probably would have kept them except I got into a big argument with their service department over re-coning the woofers. I had a friend who did his woofers and the new ones sounded really good. So I called the Dahlquist service Dept (which was located about 15 minutes from my house and inquired about betting mine done. They told me there was a 6 week wait for service. I told them that my speakers were currently working and I was doing this for upgrade purposes. I didn't want to be without sound for 6 weeks so could I just make an appointment now ad drop them off in 6 weeks when it was my turn. They said absolutely not, the 6 week clock would not start running until they had the speakers in their shop. Well at that point I figured I don't have to do them now, but the foam was approaching the end of it's life and when i did need to get it done I would be without sound for 6-8 weeks. So I decided to sell them while they were still in working condition (took me all of one day) and buy myself a new pair of speakers. That one bad encounter turned me off t the whole company (I never thought back then that there were several alternatives to getting them done at the factory). Not long after that Jon Dahlquist was in a very bad car accident and while he was in a coma for quite a few weeks his kids sold the company out from under him and from then on Dahlquist went the way of JBL and many other brands where the name was just a trademark on a product made by some mass market manufacturer.