Author Topic: Econowave Speakers  (Read 96298 times)

Tytte71

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Re: Econowave Speakers
« Reply #240 on: June 08, 2012, 01:23:53 AM »
I can't do infinite baffle test, but I can test the driver free air outside.

I can also measure with the cabinet stuffed solid with acoustic damping.

Measuring driver free air and then with cabinet stuffed would be interesting... Free air measurements to find if the null is gone and stuffed box to see if it is possible to find a workaround with your cabinets if internal reflections causes the bump.

I don't notice the 750Hz null much, except on trumpet recordings that I've listened to for 35 years, then only if I concentrate and look for it. I do notice the warm midrange glow of the bump just below at 400-600. I'm hoping that's room related.
I would recommend concentrating on the null first. Eliminating this might also eliminate or show irregularities that otherwise could fool us.

If interfering waves cancel with floor bounce, can they not also combine to make a peak at adjacent frequencies to the null?
Reflections within 0-20ms would add to our perceived frequency response. Bouncing waves will induce phase shifts and can sum up to a nasty result.

One thing I am noticing is that the speakers sound really good out of the sweet spot, especially far away, owing to the good power response, and the pro-audio origins of the design (horn + woofer.)

The speakers seem to reveal flaws in recordings very well. I think some of the flaws are still in the speakers, but some stuff is obviously recording related. There are a lot of bad recordings out there! Maybe a good reason why tubes go well with horns.
Glad to hear you are getting some good stuff from the boxes already :D
But, is there a distinct difference in sound balance in the mid/tweeter band when listening off-axis compared to on-axis?

Offline richidoo

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Re: Econowave Speakers
« Reply #241 on: June 08, 2012, 07:24:50 AM »
I chase the worst problem first to stay motivated and make progress.

I have some sawhorses that are the perfect height to invert the speakers while maintaining same tweeter height. That will illuminate any floor bounce effect. I have always liked bass drivers to be elevated anyway, but not a practical mod for this speaker.
http://mehlau.net/audio/floorbounce/
Floor bounce supposedly centered at 315Hz at current position.

Sounds is consistent off axis, best I ever had in this regard.

Tytte71

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Re: Econowave Speakers
« Reply #242 on: June 08, 2012, 09:53:53 AM »
Those damn sound waves - why don't they just move in a straight line towards our ears :roll:

I see - raising the speakers! I would then detail my answer to theprevious question a bit.
If interfering waves cancel with floor bounce, can they not also combine to make a peak at adjacent frequencies to the null?
Nyes... Yes if the first reflection was the only thing causing the dip. No since I believe that we also see ringing, similar to resonance/standing waves.
Adjusting floor height/bounce to linearize the frequency response could make things look better but will not cure the time domain issues.

It would be nice to see you measurements when you have raised and turned the cabinets  :)

Offline richidoo

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Re: Econowave Speakers
« Reply #243 on: June 08, 2012, 10:39:18 AM »
I'll need some teenage assistance to raise the boxes. With drivers they feel like 100#

Here is a graph of three close measurements.
Blue is mic 10" from the driver cone, off center halfway between phase plug and surround.

Green is mic 1/4" from surround, mic parallel to driver axis, front baffle thickness next to mic tip.

Red is mic 1/4" from driver cone halfway between phase plug and  surround.

All raw measurements, no gating at all. Signal after XO filter, horn playing, but mic is outside the directivity of the horn.

Looks to me like this dip is not room acoustic phenomena.

Stuffing the bird next

Offline richidoo

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Re: Econowave Speakers
« Reply #244 on: June 08, 2012, 10:54:59 AM »
No change after stuffing the speaker tightly with poly fill. Mic position same as red plot above, 1/4" from mid radius of driver cone, see pic. Stuffed curve is purple.

HOLM.zip emailed so you can check the impulse. I can't figure how to zoom in like you did.

Outside free air is next.

Offline richidoo

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Re: Econowave Speakers
« Reply #245 on: June 11, 2012, 05:05:12 PM »
In tribute to our esteemed visiting guest, Evan1, I refrained from posting about my speakers until it fell off the front page list. Now that he's gone...

The tweeter resonance is 600Hz, and could be causing the midrange bump at that freq. I have parts for a LCR damping filter which I will try tomorrow. Thanks to mgalusha for suggesting this at least a month ago...  :duh

Edit: Actually the bump is there with woofer only tests. But worth a try anyway to see what it does, if anything.

The dip at 700 on the AE woofer was seen in free air FR sweep, and corresponds with a small blip in the impedance curve, and is common with high Xmax drivers like this. The cloth accordion surround M version of this speaker is said by the mfg to have less surround resonance.
« Last Edit: June 11, 2012, 07:03:43 PM by richidoo »

Offline Face

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Re: Econowave Speakers
« Reply #246 on: June 13, 2012, 10:37:11 AM »
The dip at 700 on the AE woofer was seen in free air FR sweep, and corresponds with a small blip in the impedance curve, and is common with high Xmax drivers like this. The cloth accordion surround M version of this speaker is said by the mfg to have less surround resonance.
The M has higher efficiency, but a smaller x-max. 

It's all about trade offs.  ;)

I have 4 TD-10M's here that I'm waiting to do something with.  Maybe I'll pair them with some SEOS 12's.

Offline richidoo

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Re: Econowave Speakers
« Reply #247 on: June 13, 2012, 11:13:22 AM »
I have 4 TD-10M's here that I'm waiting to do something with.  Maybe I'll pair them with some SEOS 12's.

Sweet!  :drool:

Offline richidoo

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Re: Econowave Speakers
« Reply #248 on: July 09, 2012, 02:35:20 PM »
SEOS-12s horns in the house!

And so with the removal of the QSC horns from this project, there is nothing left of Zilch's Econowave Deluxe but the inspiration.

So I'll start a new thread for future developments.

Offline Face

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Re: Econowave Speakers
« Reply #249 on: November 09, 2012, 06:43:30 PM »
The dip at 700 on the AE woofer was seen in free air FR sweep, and corresponds with a small blip in the impedance curve, and is common with high Xmax drivers like this. The cloth accordion surround M version of this speaker is said by the mfg to have less surround resonance.
The M has higher efficiency, but a smaller x-max.  

It's all about trade offs.  ;)

I have 4 TD-10M's here that I'm waiting to do something with.  Maybe I'll pair them with some SEOS 12's.
Slow work takes time...



Aside from the finish, the center is done.  Glue is drying on the first main tower as we speak.  Hopefully both are done in a week or so.  
« Last Edit: November 09, 2012, 06:45:10 PM by Face »

Offline richidoo

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Re: Econowave Speakers
« Reply #250 on: November 10, 2012, 06:35:36 AM »
Looks nice Mike! The two separate racks work out great, huh? Are you gonna paint it RED or black?

Offline Face

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Re: Econowave Speakers
« Reply #251 on: November 10, 2012, 06:46:56 AM »
The TV height worked out within an inch too. 

Going with black this time around.  Not sure what finish yet though.