Zilch's AK Design Collaborative - Econowave Speaker
- Thread starter Zilch
- Start date
The first photo shows the box and woofers. The baffle is 3/4". When the baffle is mounted the front of the baffle sits 11/16" back from the front edge of box. The second photo shows the woofer mounted from the inside. The portion of the duct showing is 2 1/8". Lots of adjustment in woofer and horn depth. Thank you EarlK for telling me about the timing/delay setting. Now I know more about the xsim program. Learning is fun.
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Hi Katalyst,
Those nice "inky" black cones certainly look to be bona-fide JBL product.
A friend of mine has a few just like those ( very black , very sharp! ).
If you end up needing .frd and .zma files for stock JBL 2204H's , let me know and I'll borrow one from my bud to create some files for you.
What's the cu' of that cabinet?
Those nice "inky" black cones certainly look to be bona-fide JBL product.
A friend of mine has a few just like those ( very black , very sharp! ).
If you end up needing .frd and .zma files for stock JBL 2204H's , let me know and I'll borrow one from my bud to create some files for you.
What's the cu' of that cabinet?
3.8 cu.ft.. These with the added mass ring from the 2235 (35gr) would be somewhat different. Gordon said he had the mass rings from nos .
That would be nice of you. As long as it would not be a bother. The parts were ordered Friday and arrived today (Saturday). Now that I have the waveguide to size with. It may fit in the box with the woofer on a new baffle. Some volume would be lost so retuning would be in order. Here are the toys to play with.
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Thank you EarlK. I will keep the Wave on top. The center of the horn is 31" when on the top of the bass bin. I have been running the woofers in the boxes without any crossover. They are starting to loosen up/break in. The design of these is still very fluid. Not set in stone by any means. This is the interesting part to me. Seeing where the flow takes me.
I temped up the woofer portion of the crossover using Zilchnuts. The picture attached is the xsim with the woofer section only and the actual response measured. The curve is real close to the sim. EarlK I adjusted the delay/offset for each driver as measured with a ruler.
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That looks good. The low-pass filter is certainly working.
Here's a close-up for those who want to scrutinize the action.
Okay, attached below is the promised XSim file ( with the embedded .frd and .zma files made using my friends 2204H ).
Here's what I would design ( if the Z offset was found to be @ 4" ).
- The downward slope is preferred by some (?).
A note of caution;
The woofer file ( .frd + .zma ) is for a bona fide JBL 2204H with original cone & coil ( & lacking your additional mass ring ).
Therefore, the file is really only somewhat useful for your purposes when designing a crossover.
You'll see that I've created a crossover design which is applicable to my OEM woofer only, with a horn whose acoustic center ( AC ) is 4" behind the woofers > which remember was only a guesstimate.
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The offset delay is the differential between each drivers Acoustic Center.
You don't have the equipment to make these acoustic measurements ( to find each devices AC ) but you can measure the distance between the two points that I'll describe below ( for you to make an approximation ).
SOME BACKGROUND:
Acoustic Centers for each of the two drivers need to be acoustically measured.
Typically the Acoustic Centers are in different physical locations and are unique to each device model ( and the location is somewhat frequency dependent > complicating matters ) .
Easiest ( with the right equipment ) is to measure "Time-of-Flight" using a 2-channel soundcard for a direct reading of the devices IR's
- Time of Acoustic flight is then read-out against a reference "loop-back" channel.
Also these AC's can be derived using multiple FR readings and then "curve-fitting" the resulting interference patterns within the FR's ( this is much messier but is sometimes the only way when using a USB based test mic ).
Moving On:
I just measured this 2204's AC ( for the 1K region) to be almost at the backside of that big magnet ( but not quite by 1/2" ).
The Peerless drivers AC is somewhere near the face of the top-plate ( that the voice-coil sits within ).
The distance between these two points ( once the drivers are mounted to the baffle ) will give you an approximation of the Z offset ( ie; driver delay to enter into XSim ).
An Example:
If one where to counter-sink each driver into the boxes baffle ( for instance ) so that the horn or woofers face is flush to the wood, then one could simply place the drivers face-down on a flat surface and measure the distance between the 2 points that I've just mentioned.
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Sometimes pics work best.
Here's Zilch physically measuring ( or approximating ) the locations of 2 Acoustic Centers.
In this pic he was looking for the difference between where he assumed each drivers voice-coil is located.
Two people agreed the 2 AC's were around 60mm ( 2.36" ) apart > with the horn driver's AC behind that of the woofer.
See if you can figure/imagine the two points Zilch choose/measured ( using info from my previous post ).
Here's Zilch physically measuring ( or approximating ) the locations of 2 Acoustic Centers.
In this pic he was looking for the difference between where he assumed each drivers voice-coil is located.
Two people agreed the 2 AC's were around 60mm ( 2.36" ) apart > with the horn driver's AC behind that of the woofer.
See if you can figure/imagine the two points Zilch choose/measured ( using info from my previous post ).
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Yep, those red lines approximate the positions that I'm talking about.
Make some measurements ( of Z-offsets ) / enter that number into XSim and then see if you can make a crossover with a smooth transition between woofer and horn.
You might ( in fact ) find that the AC's ( when ) closer like this, alter the crossover topology ( sometimes pretty radically ).
Make some measurements ( of Z-offsets ) / enter that number into XSim and then see if you can make a crossover with a smooth transition between woofer and horn.
You might ( in fact ) find that the AC's ( when ) closer like this, alter the crossover topology ( sometimes pretty radically ).
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How are those modified 2204H woofers working out for you?
Have they broken in yet and are they giving you more bass?
This pic of yours ( all the while considering every horizontal line is a 5db marker ) shows that this woofer is rolling off quite drastically below 150hz ,
> hopefully that's no longer the case.
Have they broken in yet and are they giving you more bass?
This pic of yours ( all the while considering every horizontal line is a 5db marker ) shows that this woofer is rolling off quite drastically below 150hz ,
> hopefully that's no longer the case.
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I have been cutting the new motor boards/baffles. I will know more once they are tuned and hooked to the PS 200 Crown amp. They have very little time on them. The graphs I posted were close to the grill. There was no room gain in the graph. GordonW suggested a 35hz port tuning which is what was used for the graph.
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Ahh, so they're not broken in yet.
FYI, to get an idea of a woofers linearity ( above @ 90hz ) I close mic the cone ( within 1" of the paper ) 1/2 way between the inner edge of the surround and the glue line of the dustcap.
That's how this response trace was captured for this stock 2204H.
FYI, to get an idea of a woofers linearity ( above @ 90hz ) I close mic the cone ( within 1" of the paper ) 1/2 way between the inner edge of the surround and the glue line of the dustcap.
That's how this response trace was captured for this stock 2204H.
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The Fuxtor
Addicted Member
You get this sorted??
