cubby01
aka Buck
Easy enough to get into an Excel table here but I donno how to get it back into the thread...
Zilch's AK Design Collaborative - Econowave Speaker
- Thread starter Zilch
- Start date
Easy enough to get into an Excel table here but I donno how to get it back into the thread...
ROSSO
Active Member
Hence the conundrum. I started with an Excel spreadsheet, but the c/p function doesn't maintain the columns.
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Russellc
Addicted Member
This is why I queried if anyone here had used Waynes HP, and if so, if they had done any delay measurements on it. The reason I'm interested is that the 290H that Wayne uses is even deeper than the QSC. Perhaps Wayne could chime in, I understand his professional position, and will probably just suggest we use that guide with the 4Pi compensation, but I think it would be instructive to see how Wayne overcame this "depth of waveguide problem".
That said, the 290H is rectangular, and would allow for a slightly closer fitment in relation to the woofer, possibly eliminating some of the problem, or at least not agravate it as much?
russellc
Russellc
Addicted Member
Thanks for the info Wayne, I wasnt aware of the difference between the S&L units and the parts express unit.
Russellc
It seems to me that there could be deeper drivers out there. Even though this is outside the Econo part of the project, the 12" or 15" Lambda "M" drivers are fairly deep. I heard from can't remember where that the Lamdba TD 15M used an Altec cone. If that is indeed true, maybe there are good and useful Altec drivers out there that would not cause the time alignment issue.
Wayne Parham
Active Member
I first calculate phase of the crossover and find acoustic phase using Hornresp. These things, combined with the physical offsets, allow me to estimate the total system phase, which is really what sets the position of the forward (major) lobe. Then I dial it in with iterative measurements.
Remember that the length sets a fixed delay but phase creates a delay that is relative to frequency. Remember too that horn loading tends to make the acoustic phase closer to zero, whereas the unloaded diaphragm is more reactive, i.e. more phase shift. As the system transitions from one more to the other, as frequency rises and the horn begins to provide loading, it has a peaky phase curve, alternating between resistive and reactive, being partially both. The longer the horn, the lower this frequency is, and as a rule of thumb, you can expect it to start loading at 1/4λ, and become mostly resistive around 1/2λ.
Just making preperations to slap an ewave on top of the Technics SB-6000A's I picked up.
I was really surprised how much low-end these things made from a single 12" and how nice the imaging was from the tweeter.
Took some measurements:
Being that these are a 6-ohm system, i was relieved to pull the woofer and see "8 ohms" stamped on the back. Not the sturdiest cast frame I've ever seen. But, still a ton better than stamped.
Here's what I got out testing the woofer in WT3. I wasn't sure about the actual sensitivity of the driver, so I simply used the system sensitivity of 93dB. I also wasn't sure about how to measure the piston diameter, so I took the total diameter of the cone and the surround.
I was really surprised how much low-end these things made from a single 12" and how nice the imaging was from the tweeter.
Took some measurements:
Being that these are a 6-ohm system, i was relieved to pull the woofer and see "8 ohms" stamped on the back. Not the sturdiest cast frame I've ever seen. But, still a ton better than stamped.
Here's what I got out testing the woofer in WT3. I wasn't sure about the actual sensitivity of the driver, so I simply used the system sensitivity of 93dB. I also wasn't sure about how to measure the piston diameter, so I took the total diameter of the cone and the surround.
Piston diameter is usually measured to the center line of the surround.
Now, measure the impedance of the woofer in the cabinet, and you'll be able to determine where it is actually tuned. Just run the leads out the port.
That looks like quite a nice woofer, BTW.... :thmbsp:
Here's what it looks like in the cabinet. Looks like they tuned it right around the 27.59Hz resonance freq. While I'm talking about it, I should note that the overall sound quality of the stock system tells me they are asking the woofer to do too much mid-range work. Here's hoping I get better voicing once I get the ewaves on top.
What's the crossover frequency of the stock design?
The SB6000A is a 2-way speaker, right? Just woofer and tweeter? IIRC, it's just the woofer and a 1" dome tweeter. If so, it's probably not the woofer that can't go high enough... it's the tweeter, not able to go down to 1200 Hz properly.
I'd expect the E-wave high-frequency setup would work a lot better than a 1" dome, in meeting that woofer. Plus, you might be able to recoup some of the costs, by selling the original dome tweeters to someone with SB-7000s (three way, 14", 4" and tweeter), or any of the larger 3-way systems in this series, with blown tweeters. I've seen several pairs of those that needed tweeters...
Regards,
Gordon.
I'd expect the E-wave high-frequency setup would work a lot better than a 1" dome, in meeting that woofer. Plus, you might be able to recoup some of the costs, by selling the original dome tweeters to someone with SB-7000s (three way, 14", 4" and tweeter), or any of the larger 3-way systems in this series, with blown tweeters. I've seen several pairs of those that needed tweeters...
Regards,
Gordon.
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Tube King
Active Member
With the home made JBL C36 cabinets should I brace or dampen them any?
Also, does anyone have the part number for the legs? I hear they are IKEA legs and duffinator was the original to find them.
My parts express order came in today ... misisng a few items (back order) and the cabs aren't built yet but in a month or three I should have these things up and running!
Also, does anyone have the part number for the legs? I hear they are IKEA legs and duffinator was the original to find them.
My parts express order came in today ... misisng a few items (back order) and the cabs aren't built yet but in a month or three I should have these things up and running!
Yes, a horizontal brace, at least. Problem is, you still want the front baffle to be removable, so the brace must be, as well. Search this thread with keyword "Simpson" to find my scheme to accomplish this, which has been used by at least one other eWaver successfully.
It was Mxlews who found them, actually. They are not tapered like the original JBLs, but look nice as a substitute. Searching with keyword "IKEA" will turn them up, very likely.
The originals go for ~$300 a set of eight, when you can find them. The larger ones I used were about half that, as I recall.... :yes:
Tube King
Active Member
Thanks, found it without a problem.
Hmmmm, they look different from duffinators original legs as his were tapered though not to a point like his NEW JBL legs.
On another note, we had talked about ports, front, rear, bottom, etc with this cab. Is there a place that is better than another? Front? Where am I going to find space for that? How big should the port(s) be? And how deep (long) should the tubes go? I'm sure this is going to have to be a listen and calculate but approx where should I start?
Edit:
Found the legs Duffinator was running ... I think.
http://www.salamanderdesigns.com/syn/synergy.jsp?modelbase=sa/sf
You actually posted a VERY interesting link which is going to cause me a whole lot of grief ...
http://www.tablelegsonline.com
hmmmmmm .... http://www.tablelegsonline.com/shop/sleek-4-tapered-p-173.html?cPath=17
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