Econowave - looking for a tube friendly dynamic speaker?

[Paul Spencer]

There is a speaker design that seems to be taking off in the US so I thought I'd point it out to the SNA community. It's called the Econowave ... hmmm reminds me of the Econovan and those cheesy ads with Con the fruiterer! ........

Well, this speaker is efficient, has controlled directivity, has serious bang for buck and it's really cheap! Perfect for those that want to get technical and play around. Perfect for those who just want to build something without knowing the techy stuff. These guys have it sorted - you could order the parts right away and have it done before Christmas.

So the concept is this. You get a lowish cost pro driver, say a 10 - 15" midbass, a low cost compression driver and an off the shelf cheap waveguide, then a simple bog standard chunky box. About $150 for a good woofer and around $80 for each compression driver.

I've written about it in more detail here:

http://redspade-audio.blogspot.com/2010/11/introducing-econowave-speaker.html

... and if you have endless time (who does) you can try to follow the US threads.

Hopefully we will see some Aussie Econowaves happening (I plan to do some for surrounds). They would ideally suit valve lovers who don't want to give up output, those who have difficult bright rooms they can't treat and those who like their music/movies loud and clean, effortless and dynamic.

[gainphile]

I want to hear these waveguide-based speakers as there are so many threads in diyaudio and geddes. But not sure about building one. My imaginary problem is that transition from omni to forward directional.

What is the waveguide being used and what is the polar plot?

Thanks

[Paul Spencer]

Andi, you'll be hearing a waveguide/CD speaker pretty soon.

If you follow the links you will see more off axis plots than you will normally see, because this is where these designs excell. The goal is the match the dispersion at the crossover point so it is a smooth transition. I actually think open baffle would get more interesting with waveguides since you are going to control the dispersion to a greater extent. While an open baffle reduces lateral reflections, you are still transitioning from a 1" dome to an 8" cone. I'd be more concerned about that than the transition to omni around 300 Hz where this aspect becomes far less critical.

If you are using a 6" mid then it could be worth trying a matching waveguide. I believe they can work quite well for a dome where it's not too big. A phase plug is ideally needed.

[Antripodean]

If you are using a 6" mid then it could be worth trying a matching waveguide. I believe they can work quite well for a dome where it's not too big. A phase plug is ideally needed.

Most pro drivers are 10 to 15" as you said. I see it as a change to the XO and a specific choice of WG to also optimise controlled directivity along with having higher sensitivity.

[gainphile]

Ok. So the reason I could not see graphs/pictures was that I needed to register... All good now.

Very interesting. Why is the speaker turned upside down?

The polar response looks good 1khz and up.

Very keen. The cheaper version cost $190 which is not too bad considering what Geddes charge.

[gainphile]

My midrange is actually 8". This is my "final" loudspeakers:

http://gainphile.blogspot.com/2009/11/s12-ob-open-baffle-simplicity.html

Indeed the midrange-tweeter transition in this typical dipolar setup is a known limitation. But it's not too bad plus I can maintain rear radiation using back tweeters.

So if I want to try an 8" waveguide what would be the choice of compression driver + WG brand? And is there any available polar plots?

I am just starting to go through the thread at AK. Information overload indeed.

[Paul Spencer]

Upside down - well it is sitting on a work bench, not set up in a room for listening. (Your guess is as good as mine)

There is a summary here:

http://techtalk.parts-express.com/showthread.php?t=215536

That's the place to go if it all seems overwhelming. No sign up to see the images. Did the images not work on my blog?

So if I want to try an 8" waveguide what would be the choice of compression driver + WG brand? And is there any available polar plots?

I'm not sure if you would actually need a compression driver for an 8" waveguide. Genelec use waveguides in some of their models with dome tweeters - if you look up their large studio monitors you will see polar response examples with CDs and domes both in waveguides. They use a 6" mid (PHL I think) also in a waveguide. Their waveguides are quite elaborate.

The Selenium CD that gets used has a screw on arrangement which works with off the shelf waveguides, although I get the impression that people generally find non titanium CDs like B&C DE10 to be more appealing.

I believe you might want to look at the Dayton 8" waveguide at parts express. They are screw on mount, so you either saw off the screw (Zaph did this in one of the speakers on his website), or use a threaded CD.

You can find polar response plots of domes in waveguides around the place.

Here's one

http://www.aeronet.com.au/waveguide.htm

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

[fury]

http://www.altronics.com.au/index.asp?area=item&id=C6127

This is a 166mm waveguide also known as the MCM waveguide used by Troels here: http://www.troelsgravesen.dk/C17_II.htm

[Paul Spencer]

Good find! Although an 8" version would most likely be better. The idea is to match the size.

[fury]

I agree, sadly not many options available locally.

I have a pair of the Altronic ones here I have been meaning to marry up to a pair of Vifa XT25's for a long time now.

There were measurements for this pair somewhere and the results were very impressive.

Just have to work out the best way to cut back the mounting flange on the waveguide.

[gainphile]

Ok. so I've done few reading. The plan is

Waveguide 8" or 10". So long as it fits 29cm wide baffle for my dipoles.

10" waveguides which I already have:

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=270-310

I may import the 8" version while at it. I will measure both and see which has the best polar plot

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=270-308

And this is interesting too, the one which is being used by Zilch of "Econowave"

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=292-2572&FTR=292-2572#windowcontent

Now, the drivers.... those waveguide have "1-3/8"-18 TPI" mounting except the last one which is "1-3/8"-18 UNEF" (what's the difference?). So the logical choice is to use Selenium D220Ti-8 compression driver. But I keep reading gripes about this driver in the forums and apparently the B&C DE10-8 is better (?)

Selenium D220Ti-8

B&C DE10-8

The B&C will require adapter:

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-323

Is this plan sound? I haven't seen any polar plots of the combination between those drivers and waveguide. And where do I get those Geddes foam???

Edited November 11, 2010 by gainphile

[Antripodean]

Gainphile, everything except the adapter is a good idea. This area is critical for the CD so it is best to choose a WG/CD combo that is connected directly. There is a fair bit of opinion that mylar is better ("smoother") sound than titanium for the diaphragm, hence the B&C. I'm getting together a few parts for an econowave (10") so I will see what parts I have left that may be of interest to you.

[gainphile]

Roger, what WG do you have "left over" ?

Zilch has replied to my queries at AK. He does not recommend the round WG. Apparently the vertical lobing is bad.

I am now very interested with PH612 + Selenium D220Ti-8. No adapter needed and good reports from users (?). Plus if it didn't work out with my dipoles I could always build a true econowave loudspeakers and get 120db

What is your WG and Driver combination and do you have polar plots?

[Paul Spencer]

Will be very interesting to see Andi! You guys will probably have them up and running before I have a chance to get started!

The Selenium is nice and easy with the screw on mount. All the B&C are a bit of a pest because they bolt on. If you have a look at the B&C waveguides (which are a lot more expensive and use different profiles), they allow for you to screw on.

General consensus seems to be that Titanium isn't the best for home use. I believe it's a popular choice for pro high power applications where it is robust. Also, in a pro situation you are dealing with a crowd that attenuate the sound a lot, and you listen over distance. Someone commented about a particular speaker that sounded fine in a pro setup at distance, but they tried the same speaker at home close range and outch! The most popular CDs use other materials. B&C DE250 and Beyma CP380M seem to be some of the most popular units for home use. Polyester, Mylar, etc seem to be preferred.

I've used an Aluminium dome and managed to get it to sound very sweet, while others described it as harsh. Yet I've heard silk domes that were closer to harsh than the Vifa D25 how I used it. So who knows, it might need some response shaping.

Regarding the circular vs asymmetrical. That's open to debate. I believe that the ideal is more elliptical. Circular is probably better than square. The idea with the Econowave is to restrict the vertical to avoid ceiling reflections further. Earl Geddes uses ceiling treatment with circular waveguides.

For a knock up to try it out I wouldn't be too concerned, but for something you plan to live with for some time ... Roger's unity is square - would be difficult for it not to be. I'm thinking I'll turn up a 15" OS waveguide at some point, but these pre made ones are a good way to test.

Another thing to consider. As you make the waveguide narrow dispersion in one dimension, I believe it can affects the cut off.

[Henry Vu]

Is this similar to the old altec speaker systems?

I was thinking about going this direction myself with altec drivers albeit in a slightly different format. Large woofer and a wide band horn.

[Paul Spencer]

This is a development of older designs. It was typical in the past to accept narrowing response up higher. As a result, they were often either too bright or too dull depending on where you sit. The idea was to try to squeeze out as much efficiency as possible. This newer design aims at constant directivity. So the response is consistent over 90 degrees and they behave better in relation to the room. They also avoid some of the compromises of older designs.

I've found that these older designs are often riddled with problems. Many vintage speaker pre-date TS parameters - they were still figuring out how to get a speaker to work properly in a box. Many of those older boxes had plain awful bass!

So I think you will find that a decent Econowave will perform much better.

[gainphile]

This DJCITY waveguide is eerily similar to PH612 sold by partsexpress. Better yet, they're $20 a pair.

http://www.djcity.com.au/products/yd-l033-horn-abs-resin-162x303x107mm_1025.html

Compare it with PE's

I still need the Selenium CD. I haven't seen local seller yet.

[tuyen]

hens,

I think you will find the old vintage Altec drivers (15" 416, 515 woofers etc and high freq compression drivers ie. 288, 290, 291, 299) are of a different class to the ones shown in the Econowave video.

[lowpoke]

hens,

I think you will find the old vintage Altec drivers (15" 416, 515 woofers etc and high freq compression drivers ie. 288, 290, 291, 299) are of a different class to the ones shown in the Econowave video.

Absolutely! Very different price range too.

[Antripodean]

Roger, what WG do you have "left over" ?

Zilch has replied to my queries at AK. He does not recommend the round WG. Apparently the vertical lobing is bad.

I am now very interested with PH612 + Selenium D220Ti-8. No adapter needed and good reports from users (?). Plus if it didn't work out with my dipoles I could always build a true econowave loudspeakers and get 120db

What is your WG and Driver combination and do you have polar plots?

What I have "spare" is JBL 1" thread-on Progressive Transition, Part# 338800-001, 90° x 50° dispersion pattern, flange dimensions 12" W x 6.5" H, 6.25" deep. These are econowave approved.

I need to do polar plots on my XT1084 + Faital Pro Neo CD. Any assistance is welcomed ;-) About time I made a trip to Bonbeach :-)

[gainphile]

PM sent !

I'm about to place order for the Selenium CD and other "experimental" stuff.

I'm happy to host a "Waveguide GTG". It has to be a nice day as we will take the measurement outside.

Birds/lawnmowers permitting.

[Paul Spencer]

Good find Andi!

I must admit, I'm a tad surprised as I didn't expect you'd go for something like this! Still, I think some of Geddes' fans were once Orion owners.

Wg GTG sounds like a good idea

tuyen,

Not sure what you are comparing them to. But as a general comment regarding vintage compared to modern drivers ... and please do keep in mind I'm talking in general here, not so much about specific drivers.

What did they know then that we don't know now?

What do we know now that they didn't back then? Has nothing been learnt in the decades in between?

Vintage drivers typically predate TS parameters. Back then, fitting a driver to a box was by trial and error. Now, the behaviour of speakers is so much better understood that it has become a sinch to fit a driver to a box. I could teach a 12 year old to do it.

Much has been learnt about driver design since then. We have sophisticated tools now that were not available back then and the technology has moved ahead. However, many vintage drivers do involve a certain perception that they are somehow better. So a premium is added in many cases that has nothing to do with performance.

If you are prepared to spend about $400 - 500 you can get a very good quality efficient driver. B&C, PHL, Acoustic Elegance and probably also 18sound, Precision Devices. I'd much rather have those drivers than anything vintage. For about $150 you can get some decent entry level pro drivers like some of the cheaper Beyma units.

I don't know how much you would spend for a vintage driver, but I have heard prices many times that make me scratch my head. I can understand Vintage cars being worth something, as well as antiques. But speaker drivers?

The word vintage always seem to inflat the price relative to performance. I doubt you could find anything that can compete with well chosen modern $400+ drivers, but if you did find something, the cost would likely be quite a bit more and lifespan and reliability substantially less.

[Henry Vu]

I was just talking "concept" Tuyen.

It might be nice to start off with something like this and then maybe move towards a more "expensive version" in the future.

[gainphile]

Good find Andi!

I must admit, I'm a tad surprised as I didn't expect you'd go for something like this! Still, I think some of Geddes' fans were once Orion owners.

Why not? I've built dipoles and omni's. Next obvious build is a CD horn . I was just not impressed with $$ of gedlee kit. Mr. Zilch to the rescue.

After some thoughts and observation I think dipole mid + CD is a bad idea because the rear radiation needs to be maintained.

So I am now planning a "proper" Econowave build.

I just won a pair of these from eBay at $50 a piece. Good bargain ?

Eminence Beta 12a

Sensitivity 98 dB

I am already dreaming of playing my collection of Hozzam Ramzi percussions on these beasts. My 40 watt Class D should provide a healthy 115dB output.

My Selenium CDs are being shipped as we speak. Very excited and thanks to Mr. Bernanke for devaluing their dollar

Edited November 13, 2010 by gainphile

[Paul Spencer]

I'll be watching with great interest Andi!