Zilch's AK Design Collaborative - Econowave Speaker
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Russellc
Addicted Member
Bauhausler
Rational Subjectivist
Mine arrived today. These will fit across the baffle rim of a Utility Original Large Advent. If I'm lucky the waveguide hole will be big enough so I can pass the woofer through and back mount it, improving the horizontal offset by 3/4".
Props to QSC for sharing with us hobbyists what's basically a little-used replacement part for their production speakers. They're not in the retail parts business but they took care of us anyway. Thanks!
I'm pretty much off the ewave bandwagon for a while. I have 3 pretty serious projects to do
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donprice
Wound up workin' at a gas station....
Russellc
Addicted Member
Yes, you are right. Its a bolt on piece. Once my Zillion projects are under control, i'm thinking of buying a bolt-on set of 220ti. That'll be a while...
russellc
I have done that and heard it, and it is worthy.
I don't know if everyone yet gets where I'm going with this, but I view the QSC first and primarily as an eWaveguide option for use with bolt-on drivers. Many members wanted to try the DE250 drivers; we are doing that, and with the crossover component adjustments Jack worked out, it is good.
My PE Traps are now ported, and I will verify the tuning and post that soon. Then, I'll try and measure the DC300s in them, and swap in the 220Ti bolt-ons for comparison.
I'd say the QSC waveguide is likely to become another "Official" econo-option in short order here for those who might prefer its features, and the PE KD trap cab kit, as well, with either the standard JBL/Pyle waveguide or the QSC.... :yes:
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mrTT
Active Member
Thanks Zilch I got the Uwave info. Looks great!
This really is a great thread. I've been following this since the Valencia day. It never cease to amaze me the passion and the knowledge of the people who are posting here.
Question.
So there is an audible difference between a screw on type vs. bolt on type? Is it significant? Is it worth it to convert screw on to bolt on type?
Hey skywave-rider! How are you doing? Long time no see! Good to see your posts here. :thmbsp:
This really is a great thread. I've been following this since the Valencia day. It never cease to amaze me the passion and the knowledge of the people who are posting here.
Question.
So there is an audible difference between a screw on type vs. bolt on type? Is it significant? Is it worth it to convert screw on to bolt on type?
Hey skywave-rider! How are you doing? Long time no see! Good to see your posts here. :thmbsp:
ROSSO
Active Member
Just my 2 cents, others may have different experiences: If you are the kind of person who tends to put things together once and leave them that way, I would recommend that you buy the style of driver that fits the horn or waveguide you intend to use. If you like to experiment and swap things around, I believe that bolt on drivers offer more flexibility.
Personally, I can tell no difference between a bolt-on driver with a good quality threaded adapter and the same model threaded driver. The resulting assembly is virtually the same length as the purpose-made screw-on variety. I can't say the same for threaded drivers screwed into bolt-on adapters, which results in a longer stack-up of dimensions. Can that be measured acoustically? I don't know.
For this reason, where I have a choice, I like to buy bolt-on drivers and a couple pair of decent threaded adapters. That lets me swap drivers between horns and waveguides if I want to see how a particular combination sounds.
Pio1980
AK Member
I've been what-if-ing a large Advent project in my head for a while and thot ;
What if a board about the same thickness as the grille posts, with a step-down to the woofer portion, was sealed to the upper baffle and the whole recut for the waveguide, close to the woof, to bring the waveguide forward. I suppose you could still move the woof to rearmount on the baffle if you thot you needed more offset. A grille could be nicely velcro'ed to the result.
Another thot, why not put the control on the baffle where it is more convenient to voice the speaker to the room? The common rearmount thing has always bugged me.
What if a board about the same thickness as the grille posts, with a step-down to the woofer portion, was sealed to the upper baffle and the whole recut for the waveguide, close to the woof, to bring the waveguide forward. I suppose you could still move the woof to rearmount on the baffle if you thot you needed more offset. A grille could be nicely velcro'ed to the result.
Another thot, why not put the control on the baffle where it is more convenient to voice the speaker to the room? The common rearmount thing has always bugged me.
will the Dayton 12" round or other cheap waveguide along with Selenium 220 reach my 15TBX40 woofers? http://www.stage-expert.ro/spec_pdf/15tbx40.pdf
-or should I just go 3-way with cone mid and slot-horn tweeter?
-or should I just go 3-way with cone mid and slot-horn tweeter?
Not saying this, rather, that the best approach is to use bolt-on drivers with bolt-on waveguides and thread-ons with thread-ons.
Don't know about audibility, but there are measureable differences between the performance of drivers with and without throat adapters of sufficient magnitude that my studies posted earlier in this thread suggested crossover modifications should be developed to correct for them. Instead, for the moment, we are pursuing adapting the basic eWave design to incorporate a bolt-on waveguide.
Since D220Ti is available in both bolt-on and thread-on versions, it is logical to try the less expensive standard eWave driver in its bolt-on variant as well as the DE250, and perhaps open up an additional economy option which some builders might desire to pursue.
Page back to my recent first look at the location of the forward axis of the standard eWaveguide in OLA. What does that suggest? I'm getting better at this, and can redo it, if warranted.
Insofar as the QSC waveguide is concerned, I am largely confirming Jack's observation that small differences in driver/waveguide offsets as occur with various 10" and 12" woofers do not alter the "tilt" of the forward lobe sufficiently to warrant additional intervention in the basic eWave design. A 4.55° upward "tilt" of the forward axis is not a bad thing; for reference, 4430 is tilted 8° - 10° upward, depending upon which white paper we cite.
It is generally recognized that a crossover in the range of 1.2 kHz or lower is required to match 90° horizontal directivity with a 15" woofer, and the situation is worsened with using an axisymmetric waveguide requiring a minimum 13.5" center distance. D220Ti don't play that, basically, and no one has measured the polar response of any of the Dayton waveguides, cheap or otherwise, to assess their applicability or suitability for use in these designs.
My basic advice remains the same: for EconoWave design, stay with the documented eWave program. If you want to do something else, that's fine, too, but you'll have to rely upon other resources such as Wayne Parham's studies and developed products for guidance.... :yes:
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donprice
Wound up workin' at a gas station....
The eWave rule of thumb is for the woofer to play "competently" through 1600 Hz. I'm no expert, but looking at the response curve it looks like it gets funky below 1000 Hz and then drops like a rock just below 1600. Can you fix it by tweaking the crossover? Maybe, but it might be easier to go with a different (and considerably more expensive) HF driver/horn combo to bring down the crossover point. Perhaps a better option would be to use the woofer in a sub enclosure and then go with a high efficiency 8-12 inch mid-bass with the eWave. That is much easier to do right as it is a well beaten path. I haven't run the box models but that woofer may not give you <30 Hz bottom end you want for home theater....but it looks like an absolute monster 90-900 Hz.
thanks guys - I'm not real fond of 15trx40 - not sub material unless used in BP or tapped horn. Maybe it'll go into a kabuki tribute
Back in Feb.06 I started to measure the round 12" WG but got sidetracked and only have these on-axis traces w. 807 and 22A (& unlabeled) - IIRC it had pretty good subjective preservation of timbre off axis (lets say better than 811 lol)and not much worse in that aspect than DDS-pro 90 - if I get to feeling decent then i'll setup TrueRTA again. I've probably 20-15" but no good 12. 15TBX40 IIRC was used by Geddes in Summa til 15TBX100 came around.
here's ~ground plane of B&C vs a JBL of ~60g mms -there's less sensitivity so takes more power
ground plane - -JBL M151 vs 15TBX40 (might have been PZB40)
Back in Feb.06 I started to measure the round 12" WG but got sidetracked and only have these on-axis traces w. 807 and 22A (& unlabeled) - IIRC it had pretty good subjective preservation of timbre off axis (lets say better than 811 lol)and not much worse in that aspect than DDS-pro 90 - if I get to feeling decent then i'll setup TrueRTA again. I've probably 20-15" but no good 12. 15TBX40 IIRC was used by Geddes in Summa til 15TBX100 came around.
here's ~ground plane of B&C vs a JBL of ~60g mms -there's less sensitivity so takes more power
ground plane - -JBL M151 vs 15TBX40 (might have been PZB40)
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Pio1980
AK Member
Whoops! The Bauhausler has previously mentioned this, how could I forget. Missed it mebbe?
http://www.audiokarma.org/forums/showpost.php?p=3189525&postcount=8134
http://www.audiokarma.org/forums/showpost.php?p=3189525&postcount=8134
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donprice
Wound up workin' at a gas station....
BMS 4550 crossovers
OK. I found your crossover design for the BMS 4550 (and JBL 123A-1) in the "Interesting 60's speakers" thread. What are the crossover points? I didn't find that when reading through the thread.
http://www.audiokarma.org/forums/attachment.php?attachmentid=56259&d=1185949888
Thanks,
Don
Jack's our eWave crossover designer, and from what he says, he'll likely be working more with BMS drivers. Skywave and I both have and use them, also, so nobody's going to be "on their own" in the entirety of designing with them....
OK. I found your crossover design for the BMS 4550 (and JBL 123A-1) in the "Interesting 60's speakers" thread. What are the crossover points? I didn't find that when reading through the thread.
http://www.audiokarma.org/forums/attachment.php?attachmentid=56259&d=1185949888
Thanks,
Don
von.ah
Schultze!
Here's a wild-A idea for those who like the PE trap cab but think it is two small for the DC300: Build an extender-stand for it like Zilch did way back with the LE14 and increase the cabinet volume. You could match the angles of cut with the existing knock-down panels.
Or, you could be crazy and buy 4 trap cabs and make two enclosures out of them, sorta like member dc270 did with his homebrew Altec 19's.
I know it's a long way to go to make a budget woofer work, but it would be cool.
Or, you could be crazy and buy 4 trap cabs and make two enclosures out of them, sorta like member dc270 did with his homebrew Altec 19's.
I know it's a long way to go to make a budget woofer work, but it would be cool.
Wayne Parham
Active Member
Agreed, and this goes for front mounted verses rear mounted verses routed flush. Sometimes people will ask if it's OK to route the baffles for flush mounted drivers in one of my loudspeaker designs, if that will help or hurt performance. I always tell them they can be routed or front mounted, that it's largely a matter of aesthetics. The tolerance of the crossover components and thermal shifts do more than a fraction of an inch offset, at least at the scale we're working with here, in the overlap region of 1kHz to 2kHz. And the diffraction edge is too small at these frequencies too. It's acoustically invisible.
Bauhausler
Rational Subjectivist
I test-fitted a QSC WG to a ULA baffle. The side rim holes line up with the baffle rim nicely. All that's needed to seal the upper and lower rims to the baffle are 1" strips of wood.
I'm eager to try this but I have several more urgent projects including another magazine article.
I suspect that the first use of these WGs and DE250s will be on DQ-10 cabs, which I expect to pick up this weekend. As Zilch demonstrated, that's about the easiest implementation there is for this.