Zilch's AK Design Collaborative - Econowave Speaker

[bwaslo]

spicy, you definitely need either Lpads or equivalent resistor networks, else they'll boil your eardrums. Also after that, toe them in to a point several feet in front of your couch (not at the couch itself).

The waveguide driver is way more sensitive than your woofers.

 

[spicynuts]

Well, the lack of LPads is temporary until I build new boxes or modify the existing ones, BUT - I did follow the instructions and the spec. There is no mention of an alternate resistor network when by-passing the LPads. What did I miss? What is an alternate resistor network?

 

[Bauhausler]

Been away for a while

Howdy, ewavers. I've been away for a while working on other projects.

Just checking in with a little tech info. I'm running the following:

D220Ti/PH612
original <95 db Ewave crossover
Altec 406-8Y woofers (Altec 890C Bolero/Madera)
Altec Bolero passive radiators
JBL L77 cabinets

Checking the response with a Behringer DEQ2496 and matching mic, I find the following EQ is necessary to flatten the response at the bottom end of the tweeter's range:

+6db @ 3200 hz, 1/2 octave wide
-4db @ 2000 hz, 3/4 octave wide.

Looking back at Zilch's early response graphs, this seems to match up approximately with the peaks and dips that he found around 2K and 3K. There also appear to be impedance variations in the D220ti that correspond to these features.

Because these woofers are quite sensitive I'm running the Lpad wide open, essentially out of the circuit. I wonder if building the high sensitivity version of the XO would help swamp these impedance variations out of the response. With the high sensitivity version the Lpad would come into play and should contribute its series and parallel resistance to the compression driver's impedance.

I have the peak and dip EQ-ed out for now but I'd like to come up with a passive solution for this that doesn't require DSP to play flat.

Thanks for your suggestions and help.

 

[bwaslo]

the Lpad attenuates the level of the tweeter to match the woofer, its like a variable set of resistors. At any given setting, if could be replaced by a set of fixed resistors. If you bypass the Lpad, then the waveguide plays full blast, which would only work right if your woofer was extremely efficient. I'd guess you need something like about 10dB of attenuation (but best to use an lpad rather than guess, unless you have a way to measure)

 

[EarlK]

(i) Based on the instructions I received I soldered in jumpers to bypass the L-Pad circuit.
(ii) Well, the lack of LPads is temporary until I build new boxes or modify the existing ones, BUT - I did follow the instructions and the spec. There is no mention of an alternate resistor network when by-passing the LPads. What did I miss? What is an alternate resistor network?

> As pointed out by Bill , put the variable Lpads into the horn circuit so you can balance horn to woofer .

> The advice you've been given to go without any horn attenuation ( assuming you're actually repeating it here ver-batim ) is simply wrong .

<> EarlK

 

[Bauhausler]

the Lpad attenuates the level of the tweeter to match the woofer, its like a variable set of resistors. At any given setting, if could be replaced by a set of fixed resistors. If you bypass the Lpad, then the waveguide plays full blast, which would only work right if your woofer was extremely efficient. I'd guess you need something like about 10dB of attenuation (but best to use an lpad rather than guess, unless you have a way to measure)

The woofers are extremely efficient. To the ear and to the mic the response is well balanced with the pot all the way up, using the standard XO. No additional attenuation of the HF level is needed to balance the sound.
My question is: if the high efficiency XO is used, allowing the Lpad to be set to mid-range, will the unbypassed fixed resistance in series and parallel help swamp the driver's impedance variation out of the acoustic response curve?

This is kind of a technical issue, and depends on the contribution of the driver's impedance variation to the overall response.

 

[Bauhausler]

Ewave wipes the floor with fancy new speaker

Going back a couple of years I had an article in Make Magazine about converting Large Advents to Econowave:

http://makeprojects.com/Project/Econowave-Speakers/181/1

The pair I built in the article belongs to my boss now and they're in his man cave 'Jazz' system. Yesterday a rep from a new speaker company brought over some prototypes to demo in the hope of getting his support. They A/B-ed the new speakers against the Ewaves and the everyone preferred the Ewaves.

Sent packing by a cheap DIY vintage conversion. That had to sting a bit.

 

[bwaslo]

Hi Bauhausler,

I think my response got crossed, it was supposed to be for spicynuts' post.

But if you change to the 95+DB xovers and add the lpad to yours, that will tame the bumps some (though not a lot). The impedance peaks affect not only the crossover, but are also where the voice coil moves with less effort.

Bill

 

[bwaslo]

I just sent my ewaved Advents to my son as a gift. Still among the best sounding speakers I ever ran. The Advent woofer was born to ewave.

The shipping cost was more than I have in the speakers!

 

[Bauhausler]

Hi Bauhausler,

I think my response got crossed, it was supposed to be for spicynuts' post.

But if you change to the 95+DB xovers and add the lpad to yours, that will tame the bumps some (though not a lot). The impedance peaks affect not only the crossover, but are also where the voice coil moves with less effort.

Bill

Okay. That makes sense. I have some spare Zilchlab boards and a ton of XO parts so I'll make up a set of the high sensitivity XOs to try out. Actually, it's just one cap and 2 resistors that need to be changed. If I get tricky with a DPDT switch I can put both variations on the same crossover board.

Yes, spicynuts probably needs an Lpad, but considering the relatively sensitive JBL woofers he's using he may be within a few dbs of the correct range. In my case the tweeter level is correct, by chance, with the Lpad out of the circuit.

 

[Bauhausler]

I just sent my ewaved Advents to my son as a gift. Still among the best sounding speakers I ever ran. The Advent woofer was born to ewave.

The shipping cost was more than I have in the speakers!

I have a stash of these woofers, rebuilt & ready to go. I've found that the D220Ti/PH612 on top of a DQ-10 cab sits perfectly at the top edge of the woofer frame. And of course a LA woofer fits the DQ-10 cab.
This is heresy but I'm going to do it anyway.

At the moment I'm enjoying the Altec 406 woofers. I have 4 of the early Z version and 5 of the 8Y version. Even with the passive radiators they don't have the bottom end extension of the LA woofer, though. I think the Altecs have a slight advantage over the LA woofer in the top end of their range. They, have a textbook rolloff with the Ewave XO, sound cleaner and seem to have better dispersion (subjective, not measured yet).

ETA: To make up for the loss of bass in this large, cluttered room I'm bi-amping 'subs'. They're AR3a cabs/woofers. I'm driving them with an Accuphase P-300 amp and an electronic crossover set at around 70 hz. This doesn't mean the Altecs are weak, necessarily. This room just soaks up bass.

 

[spicynuts]

Bauhuasler, that article you linked above has been in my bookmarks for about 3 months as my guide for deciding if I wanted to do this! So, thanks for the inspiration.

 

[donprice]

The pair I built in the article belongs to my boss now and they're in his man cave 'Jazz' system. Yesterday a rep from a new speaker company brought over some prototypes to demo in the hope of getting his support. They A/B-ed the new speakers against the Ewaves and the everyone preferred the Ewaves.

Sent packing by a cheap DIY vintage conversion. That had to sting a bit.

Any chance the guys were ignoring the WAF? :scratch2:

 

[Bauhausler]

Any chance the guys were ignoring the WAF? :scratch2:

The Ewaved Original L Advents look like Advents on walnut stands. I made nice black fabric grilles for them. His upstairs speakers are black Linn Isobarik DMS. His Mrs. is fine with both.

Mine are ugly. The JBL L77 cabs were more or less presentable until I took off the grilles and 'treated' the rims with 2" tubular foam pipe insulation to break the sharp edge. Now they look janky but sound outstanding.

 

[Bauhausler]

Bauhuasler, that article you linked above has been in my bookmarks for about 3 months as my guide for deciding if I wanted to do this! So, thanks for the inspiration.

I was in this thread way back years ago. There's a separate thread (referenced on the first Econowave page) where I document converting vinyl original Large Advents. That came to the attention of a Make magazine editor. They asked me to re-write it as a short project for publication. I decided vinyl was too plain so I re-did the whole thing from scratch with a nice pair of walnut ones. The article came out about 2 years ago or something and the freelance fee was worth more than the speakers. So win/win. It wasn't a high profile item, appearing in the magazine right after a (longer) article on teaching your cat to poop in the toilet.
I don't think the Econowave article got much attention, but my next one, on a Gainclone type chip amp generated a lot of interest and the discussion thread is still going on 18 months later.

 

[Sir.Byrd]

Hello EWavers!

#93 here. I'm not around much, mostly because I'm so happy with everything that I pretty much call the system done. Finally!

BUT! I can't leave well enough alone sometimes. So in contradiction to the econo nature of the EWave, I dropped in $150 of fancy Obbligato Gold capacitors. Even more stunning. Jaw dropping. Late nights again where I can't go to bed. Just one more song! I am so happy with these loudspeakers.


I don't know much about design, and I'm only a so-so implementer. And I haven't caught up on this thread, but I do wonder, has anyone gone with an all-out crazy implementation of an Ewave? Even with this investment and building cabs, what a bargain for the enjoyment they provide.

I think this may apply, though it is more of a 4Pi than an e-wave. Similar concept though, just different crossover.
http://www.audiokarma.org/forums/showthread.php?t=320142

 

[spicynuts]

I don't think the Econowave article got much attention..

I think it's like the first or second google result for econowave though. Actually just checked..it's the FIRST result. So...it lives!

 

[Bauhausler]

I think it's like the first or second google result for econowave though. Actually just checked..it's the FIRST result. So...it lives!

I'll be darned. It used to be below Becker's earlier Ewave video for Wired (which you should watch if you haven't).

Make Magazine throws a lot of weight in the DIY publishing world, which probably accounts for the Google ranking. The print article itself didn't generate nearly as much reader involvement as the Squelette gainclone amp article I wrote.

I'll get back in a bit with some pix of the response of the 406Z/D220Ti/PH612 combo so yu can see the 2K - 3K response glitch I was talking about.

 

[4343]

...
I'll get back in a bit with some pix of the response of the 406Z/D220Ti/PH612 combo so you can see the 2K - 3K response glitch I was talking about.

I remember Zilch having some difficulty aligning the diaphragm at one point, perhaps yours needs to be rotated to one of the other positions?

I think the diaphragm itself fits in two ways, and the back cap does as well, for a total of four possible positions.

 

[skywave-rider]

I remember Zilch having some difficulty aligning the diaphragm at one point, perhaps yours needs to be rotated to one of the other positions?

I think the diaphragm itself fits in two ways, and the back cap does as well, for a total of four possible positions.

You're right. I have rotated the diaphragms and the response can improve. I can't recall in what region the response improves, though. Clean the gap, too.