Econowave - looking for a tube friendly dynamic speaker?

[zog]

Last night my mate Col came over with some parts for some new speakers he is building. Before they get created we had a play with the Selenium D2500Ti-Nd-8. compression driver, making some quick and dirty MDF stands for them+waveguides and bolting them into (on one side) a Dayton "JBL clone" waveguide, other side a DJCity "JBL clone" waveguide, running with my Econowave speakers and crossovers. We also tried a B&C DE10 compression driver using a Selenium aluminium bolt on to screw on adapter.

This is where having a minidsp would have been handy! instead was limited to a fixed crossover layout due to the resources at hand, we had the intention of just LPAD attenuating to match levels. Turned out we didn't really need to.

The D2500ti, although "on paper" 4dB louder than the D220ti, actually measured (quick and dirty Holmimpulse session) at quite close to the same output levels. So we just dropped it in, without an LPAD, sitting the extra waveguides on top of my current cabinets and had a listen. And they sounded great. Similar, but definately smoother to the D220ti. And these drivers haven't been run in, they are straight out of the box. The D2500ti and D220ti replacement diaphram is the same part on PartsExpress, so there is some similarity between the units. But the D2500ti has a cast metal (aluminium?) body and rear casing rather than plastic. And the unit is a lot smaller than the D220ti because of the stronger neodymium magnet.

We also tried the DE10, though there was a notch in the response at the crossover point as it is intended for a higher crossover frequency than the econowave design. We didn't have to LPAD as the levels matched well enough, and it also sounded very nice, quite a different quality high end (mylar rather than titanium?).

The Dayton and DJCITY waveguides have slight, but noticable differences in build, especially at the throat the DJCITY one a bit smaller and the opening slightly less round. It seemed to fit closer with the bolt-on adapter + DE10 rather than the Dayton one.

The two Selenium D2500 drivers also had a different measured frequency response at the high end (above 13K), it will be interesting to see if this changes once they are run in a bit.

Some pictures and graphs to be added "real soon now".

[gainphile]

Great report zog... D2500 is famous for its smoothness, but at twice the price.

How didi you like the De10 in terms of subjective observation?

[zog]

Great report zog... D2500 is famous for its smoothness, but at twice the price.

How didi you like the De10 in terms of subjective observation?

Even smoother, more delicate sound than the D2500. It sounded really very very sweet, especially considering it was dropped in to a crossover intended for a D220ti (after measurements determined it would be OK), and the 1.5K notch. I suspect now all those terms people use for the D220ti will come into play when I switch back to them.

At least I have a "demonstrated" plug and play upgrade path without even having to turn on the soldering iron for my current red speakers.

Interestingly to "scratch the itch" I'm helping Col sort out the crossover for some of the speakers he is going to build with these D2500tis. He mitigated the cost somewhat by ordering a pack of 6 from PartsExpress. Some of them are going into some passive Econowave style speakers mated with the P.Audio WM-12M woofers.

[Paul Spencer]

Interesting to hear. Are you thinking of trying MiniDSP? I think you would have some fun with it.

[zog]

Interesting to hear. Are you thinking of trying MiniDSP? I think you would have some fun with it.

yes! One will be purchased. I can see a number of uses for it besides econowave type experiments.

Great report zog... D2500 is famous for its smoothness, but at twice the price.

Factoring in shipping to Australia (D2500 smaller and lighter) the difference seems to be just 30% after fiddling with the P.E. web site.

D2500ti - heavy, finned metal back plate

rig for testing quickly knocked up out of 12mm MDF:

[Paul Spencer]

Looks like they made the exit bullet proof!

[Guest Peter the Greek]

Can anyone point me in the direction of a cheap econowave design with a passive x-over. I need a cheap high SPL rear speaker....when I say cheap I mean it <$300 a pair?

......tell him he's dreamin?

[Paul Spencer]

Elill, I think Roger is selling a pair of Selenium drivers + Pyle waveguides, quite cheap and even at their new price they are cheap. Just add woofers that are featured in one version and voila, cheap Ewave. You will have to look at the original Ewave threads to find which one you want to do. The basic idea is that a novice can do it without designing the xo, there are plenty out there. I'd say you can probably get the drivers for about $350, one sheet of MDF for $34, the crossover depends on the parts you use ... just realised you want $300/pair. Hmmm good luck there. Somebody in the classifieds was selling some 10" woofers from a cinema speaker along with some dome tweeters and a passive xo. About $160, it was a Krix, but sadly the xo was not made for those tweeters. You will have to dig.

[Guest Peter the Greek]

I need to do some more research, thanks all the same. $400 sounds more realistic at a push....problem is that'd be $550 as I need special colour matched fabric to hide the darn things......back to the drawing baord

[Paul Spencer]

Could you live with a box with black speaker gille? $15 buys quite a bit of fabric.

[Guest Peter the Greek]

Nah.......I'm too vain.....

In all seriousness, they're for the living room, they'd be mounted in a wall cavity (about 600mm so plenty of room) but they'd need to blend in (hence the fabric). I should just by some crapy BIC America in walls and be done with it (plastic grills can be painted)

Distance to seating position is about 5m....I need something with nuts

[Paul Spencer]

Can't help you there, I like my speakers naked! I'm planning a Unity and the design I have in mind will see it virtually invisible, mounted flush in a bass trap. I actually want to see something that looks like a speaker. When I go to the cinema, I get tempted to peer behind the curtains and see what is lurking there.

[Guest Peter the Greek]

Unity? is that just one big full range horn?

Edit: just googled these - interesting. Cost a cost estimate Paul?

Edit 2: these are very cool! DIY must be hard to get right, or rather the combo of drivers....and crossover?

Edited March 19, 2011 by Peter the Greek

[Paul Spencer]

There are only two Unity horns in Australia (unless someone has a secret DIY unity). I've met both owners, and heard one of them. It has a 1" compression driver usually in a conical waveguide, then 4 x 5" mids horn loaded down to 300 Hz, then you need a woofer below that. I believe the efficiency is about 109 db down to 300 Hz, then probably 96 - 98 db below that with an 18" pro woofer. Even in a passive version it's time aligned by design and apparently the measured distortion level is ultra low ie less than most amps. What is really interesting about it is that it's a coax design down to 300 Hz, and I'd consider it to be the least compromised point source that I know, with my goals in mind. After hearing many different compression driver and waveguide combinations and having heard the massive improvement with foam in the waveguide, I'm now confident I can get this to sing.

If you want to build a nice sounding DIY speaker that plays nicely with the jazz tunes, it's not that hard. You pick some nice drivers for a conventional 2 way floorstander, measure and tweak. Or you go the cheat method and build a sorted passive 2 way, plenty of them out there. I like the nice laid back sound you can get from speakers like that with well chosen drivers and the right crossover. But after a while I wanted something with effortless dynamics that could hit unlimited levels with ease. I also wanted something with a better thought out room interaction - conventional speakers are cheap to produce, they aren't rocket science to design and they sound good and keep most people happy without having to spend silly money on them.

As soon as you want to explore high efficiency and start thinking about room interaction, the challenge really starts. Efficient speakers have often been a big compromise and it can be a lot harder to get them to sound good. Many of them seem to have some obnoxious traits, but in the Unity I see some real potential. It now has been updated, the new version is called the Synergy horn, the brainchild of Tom Danley. I'd call Tom one of the most innovative speaker designers in the world today. Most steps in speaker design are really small variations and points of difference, however, some of the work that Danley is doing are of a nature that is challenging to understand. At first look, you see a pile of drivers all loading into one speaker and think "what the heck is this?!" It all looks like the mess, the creation of a mad scientist, but when you look into it, all starts to make sense. He is focused on the pro market, however, if the Unity is anything to go by, they are pro speakers that can be thought of as a hifi sound on steroids. They Synergy is a bit more complex than I'd go for, since I think 3 way + subs is the sweet spot in performance vs cost. Otherwise, I end up with too many drivers, too many amps, too many crossovers - I'm doing this completely active, eventually adding active 2 way surrounds.

I don't really need any more output than I can get out of a 10" 2 way waveguide speaker, but I'm chasing something a bit different with ultra low distortion, and I'm hoping the coax point source design will do some magic in my small room. I'm definitely no "set and forget" diyer. The journey is a big part of the fun.

Here it is:

Edited March 19, 2011 by Paul Spencer

[zog]

He is focused on the pro market, however, if the Unity is anything to go by, they are pro speakers that can be thought of as a hifi sound on steroids.

Interesting! I've been looking at some of the JBL pro gear and it looks like it would make great (though kind of industrial looking) home hifi gear. It's also notable that some of the Klipsch mega expensive speakers are available in pro audio editions without lovely wood finishes.

..plunging down the other end of the market Col pointed this speaker out, which is avail for $175 each - $350/pair:

http://www.behringer.com.au/EN/Products/VP1220.aspx

I'm curious how pulling it apart, measuring the parts and redoing the crossover with econowave design ideas would sound.

[Paul Spencer]

Edit: just googled these - interesting. Cost a cost estimate Paul?

If you were building from scratch, you'd be looking at

$350 for a pair of compression drivers

~$500 for 8 midranges

$600 - $1400 for a pair of 18" woofers

You could easily spend more, you could also spend quite a bit less if you get 2nd hand or already have some of the drivers, but it's never going to be cheap. An average DIY project has about $300 worth of drivers and that could equate to a $5k retail equivalent.

Add for the Unity 2 bits of MDF $70 and some kind of xo (you could easily spend $700 on the passive xo and still need an active xo and to bi-amp).

Unless you have a taste for the exotic ie field coil fullrangers with goats leather surrounds and ingredients blessed by Tibetan monks, the Unity is potentially one of the most expensive diy speakers you might consider. For me, however, I only need a pair of woofers and some mids. Were I to build some 2 way waveguide speakers with my preferred drivers, it would cost me more.

Edit 2: these are very cool! DIY must be hard to get right, or rather the combo of drivers....and crossover?

Usually, the crossover is the biggest challenge. Designing a box is easy, building it isn't that hard for the handyman.

The Unity has a lot more that can go wrong, it's construction is critical since small changes have a big effect. If everything else is done right, I suspect the crossover would present no major challenge. My biggest concern is getting the horn loaded mids right. Even details like the openings that load the drivers to the horn can have a big impact. You can cut holes, but ideally you need a certain profile. There are a very small number of drivers that even have a chance at working.

After grasping what this thing is about and the obstacles involved, only three types of enthusiast persist. The lucky opportunist who buys one of the few available and takes a leap of faith (probably) not having heard it. The ambitious audio nerd who sees everything as possible. The lunatic.

So I'm either the nerd or the lunatic.

Zog,

Interesting idea re: the Behringer. Elill could probably pick out a smaller version, cut away the metal grille, add some foam to the waveguide and wrap it in some fabric that gets it past the style council. A vented pro speaker with an 8 or 10" midwoofer would probably be fine, but ideally it would have a 1" exit compression driver and avoid a titanium diaphragm. The bigger drivers lack top end extension. The pro market can offer some killer value, but I'm yet to hear a bog standard pro box like that that sounds hifi. A few mods and a well chosen one could make a killer surround and sound very good indeed.

[Guest Peter the Greek]

The box is the easy bit.....understanding what you're doing is the hard bit

I have ben mulling over the idea of a pro speaker for a while, or a cheap 2 way with a horn tweeter.....

[gainphile]

I just posted my final conclusions between Dipoles and Waveguide speakers at diyAudio build thread... so here we go:

Refer to earlier posts about these subjective observations.

S15 - Econowave DSP vs S16 - Constant Directivity Dipoles

COST

Winner: CD Speakers

RESOLUTION (midrange)

Winner: Dipoles

This could simply be the quality of woofer used. The 12" simply can't match the 8" metal cone driver

SWEET SPOT

Winner: CD Speakers

BASS

Winner: CD Speaker

I changed my mind. Dipoles simply can't pressurize under 40hz in my room. Otherwise dipoles win.

MID-HIGH/Tonality

Winner: CD Speakers

IMAGING

Winner: Dipoles

SPL/VOLUME

Winner: CD Speakers

DYNAMICS

Winner: Dipoles

We have a winner: ........

In summary, the CD Speakers delivers EXCITEMENTS while the Dipoles deliver REFINEMENT. Subject to my own limitations of course.

Which one do I listen to? Well, it's the dipoles. But it's a 5-minute job to swap

[Paul Spencer]

Andi, you need speakon connectors! I can't think of anyone who needs them more than you. Switching over becomes easier. Just like plugging something in to the mains.

When you say "imaging" what do you mean? I tend to refer to the "sound stage," "sweet spot" and "imaging." My experience has been that dipoles have a big sound stage, with greater depth in particular. I find it's good for some material, poor for others. However, they tend to sacrifice image sharpness and focus, hence I would not call them superior for imaging. They tend to have a bigger sweet spot as well, but in that regard I'd say waveguide speakers, actually CD speakers have a larger sweet spot than most. Dipoles use the front wall reflection to do it, whereas constant directivity speakers with the 45 degree toe in use the off axis response to make the sweet spot bigger. The response of the closer speaker is shelved down so it acts as an acoustic balance control. An open baffle has many front wall reflections that effectively create another pair of speakers on the other side of the wall, with a lower level. With Antripodean's speakers, this goes to an unusual level where you get to an extreme off axis angle and the further speaker actually sounds louder.

Another issue is listening distance. At our last GTG I felt distance was an issue. With a greater vertical offset you need to sit further away - one reason why many horns need a bigger room. This is another reason why I think the Unity horns are interesting, because they are effectively a coax with very closely coupled mid and CD.

Decided to do my own take of your little summary ...

COST

Could go either way

RESOLUTION

Winner: depends on drivers used

SWEET SPOT

Winner: dipoles

BASS

Winner: CD Speakers + bass traps + EQ (IME there is nothing dipole bass can do that can't be done as well or better with monopoles, with lower cost, greater efficiency and much higher output)

MID-HIGH/Tonality

Undecided on that one. I suspect the ultimate there could be CD dipoles!

IMAGING

Winner: CD speakers - due to stability and focus of the imaging

SPL/VOLUME

Winner: CD Speakers (no argument there)

DYNAMICS

Winner: CD Speakers

I'm a bit surprised Andi - I think we have a different answer for just about everything! Regarding excitement vs refinement, I think that will also depend a lot of the design. In a quick and dirty design, the open baffle with typical hifi drivers will much more easily reach a stage where you get a level of refinement. However, I believe you can get the same level of refinement with constant directivity, it's just harder to get there. Have you tried the foam yet? Try it with any one of the BMS/B&C/Faital CDs and one of the better sounding waveguides and I think you will find it something of a revelation. It only takes one weak link and these things can sound awful. When I first tried the foam I had moments in which the imaging almost made me gasp in shock. It was as if I was hallucinating! Or maybe it was just being up way too late messing with foam and going loopy!

Edited March 22, 2011 by Paul Spencer

[gainphile]

Yes, as with any engineering there are tradeoff to be made and they're physics most of the time (and sometimes... funds!)

The CD requires large woofers to maintain directivity and the obvious outcome is cone weight etc. which does not go along well with mid-high reproduction. Hence resolution. So are the other topics observed.

The more important point here is that both are valid designs when it comes to sensible audio reproduction. Compare with most approach (woofer+dome tweeter) for example.

Stay tuned for my next speaker build .... the dipole / CD beater ...

[Guest]

Afternoon

So guys what is the tube amp going to be to run these tube amp friendly speakers .

Cheers

[gainphile]

How much is a 4-channel tube amps?

[Paul Spencer]

56, that may be a fair way down the track for me.

[jaspert]

How much is a 4-channel tube amps?

More than $50......

[gainphile]

Ouch !...