If the off axis response had a slight dip in the 3-6kHZ area due to the 3 inch midrange driver becoming more beamy, it wouldn't hurt my feelings. That somewhat approximates a "loudness compensation" curve).
The passive crossover has a 2 pole lo-pass and resistive attenuator (4 ohm) on the woofer to match the efficiency of the 3 inch Vifa TC driver. I could have done a 3dB/octave passive roll-off EQ but it required a fairly expensive additional coil (relatively large inductor). I don't remember the value but it made me want to go the active route. The woofers kevlar cone with it's large 3kHZ resonance also encouraged going active to get the 24dB/octave rolloff. In the end I did both (passive and active crossovers), to compare and maybe learn something.
The crossover between the midrange and tweeter is one pole passive in both cases. The active crossover only does the 500HZ crossover point and also has active EQ to make the closed box woofer be somewhat acoustically flat down to 30HZ. It's virtually done now but I'm too busy with other things to do the final testing. It's the middle of summer in Oregon.
In my soundbar project I used 5 of the 3 inch Peerless TG drivers (with the glass fiber cones), operating from 150HZ - 7kHZ, and they sound great, but needed a LOT of baffle step correction. In the future I wouldn't try to take them below 400HZ. You can only get so many SPL's out of a diaphram that small before frequency modulation distortion is likely.
That does not change anything. Good basic design simplifies some things with the room etc but is not always the best and not enough for everybody and everywhere. Golden ears will make the final decision without listening measurements and statistical results indicating that average man would select e.g. JBL design after blind test. No problem for me to listen basic 2-way with waveguide for few months but that's it.
I can listen and read really good. He explained the DI to the guys who visited his house on that video. I'm sure that he possess the necessary skills to explain coloration measurements.
ZVU,
I am curious, have you ever listened to a smaller speaker with a SEOS10 or something else similar to the Nathan speakers from Earl?
You seem to be mainly saying that the issue is with the 12 and 15" designs...what about the 10? It's smaller and crosses a bit higher....
If your argument is mainly about the size of the midrange driver, I wonder if the smaller designs will suite your fancy.
I am curious, have you ever listened to a smaller speaker with a SEOS10 or something else similar to the Nathan speakers from Earl?
You seem to be mainly saying that the issue is with the 12 and 15" designs...what about the 10? It's smaller and crosses a bit higher....
If your argument is mainly about the size of the midrange driver, I wonder if the smaller designs will suite your fancy.
I made two Econowave (Zilch inspired) loudspeakers.
1. Deltalite II 2512 + pt wg and selenium d220ti - in the middle of building process http://s16.postimg.org/od0g0nzjp/d220ti.jpg
2. Sonido SCW300 + pt wg and B&C DE250-8 http://i48.tinypic.com/34pavig.jpg
I listened to 2 types of econowave that my friends have made:
1. Beyma 12LW30 + pt wg and d220ti http://s17.postimg.org/l142o6sm7/sink.jpg
2. modified Beyma 12LW30 + pt wg and d220ti http://s16.postimg.org/ubiuon7w5/super.jpg http://s24.postimg.org/tkvg7hngl/fejzplag.jpg
I listened to Summa loudspeakers. My claims that 15" can't play too good > 400Hz is based on that and on loudspeakers that i have listened and have 15" woofer and xover frequency at arround 1000Hz. Some of them are DIY and some of them are commercial loudspeakers. Few of them are on the links bellow:
http://s24.postimg.org/dujk5ciyt/damir_1.jpg
http://s28.postimg.org/uaqen788t/damir.jpg
http://s28.postimg.org/iqdb6fibh/wg_veliki.jpg
The conclusion that i have come to is that 12" can play up to 1KHz very good but not just any 12". The ones that i heard and sounded good are two econowaves that i made, Tannoy Cheviots, JBL 2202 (in JBL 4355 boxes) and Goodmans Axiom 201. Not saying that these are the only ones good out there - it's just the ones that i listened to.
I listened to Beyma 12LW30 and did not find any flaw - mostly because all that we did listen that day was Antonio Forcione but the owner always says that he has problem with lower mids that are comming out of the midbass. That is the reason my other friend cut off the dust cap and put the phase plug (as can be seen on the pictures) just to try to cope with it but my initial concern was that it has too much weight on moving parts (membrane, coil, upper and lower suspension). I must correct myself - Beyma 12LW30 have Mms = 66gr not 77 as i previously wrote. I just rechecked it.
Anyway i think that it would have to be one bad mf of an 15" woofer to be able to play with less compromise that high. That could be Altec 416, Eminence Deltalite II 2515 (Mms=70gr, i'd love to check that out), AE TD15M.. . But not B&C 15TBX100 that have Mms=156gr.
That is the real question that Earl should answer. How come the 156gr membrane can play 400Hz-1000Hz with the same accuracy as 12gr membrane of B&C 6md38 ?
We can say that it has stronger magnet and stiffer suspension that should be able to start and stop it's moving system as soon as it can but it can never do it fast enough - or not as fast as can be done with 12gr membrane and strong motor with stiff suspension. That's my point.
Now i don't care about arguing on that topic because i tried it and now i'm making loudspeakers that i think will sound the best that they can. But i just had to say what i found regardless if someone doesn't like it.
If I would build anything with 10" midbass it would be Delite 10
http://techtalk.parts-express.com/s...-Your-PCD-Mettle/page11&p=1639915#post1639915
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If one were to try to avoid crossing in the 1kHz to 4kHz region and adopt a 4way with crossovers @ 100Hz, 800Hz and 6kHz.
What would make good drivers for the two regions 100Hz to 800Hz and for the 800Hz to 6kHz?
What would make good drivers for the two regions 100Hz to 800Hz and for the 800Hz to 6kHz?
I don't know of any other way. I can't make it by ear - as some folks claim they can.
I can make screenshots of measurements if necessary. I'm using HOLMimpulse, Behringer ECM8000 and M-audio fast track mk2 for measuring. Xover frequencies were at arround 1.8KHz for Deltalite and 1.5KHz for Sonido based econowave.
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I'd use very light coned 12" or 10" from 100-800 and 2" exit compression driver from 800-6KHz.
10" - JBL 2123, Deltalite II 2510, JBL 2121....
12" - Deltalite II 2512, JBL 2202H, AE TD12M, 18sound 12MB600 (AE and 18sound looks good but i haven't tried them yet)
For >800 Hz i would use some of the JBL 244* compression drivers. That would be playing it safe as you can.
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I found this one as i sent it by mail to my friend and asked him for advice, i'll find more when i get home:
Sonido econowave on axis 1m distance - mic placed between driver centers: http://oi42.tinypic.com/2urxkbk.jpg
tweeter reversed polarity: http://oi39.tinypic.com/dvt2z5.jpg
These were made by my friend out of fiberglass - wg with lipover: http://s28.postimg.org/iqdb6fibh/wg_veliki.jpg
It is arround 45-50cm in diameter. 15" woofer is bellow - Beyma SM115/K in a testbox. We wanted to see what happens with it and can it work with the horns above. Xover frequency is at about 950Hz.
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Good question Andrew......and that's what this thread is trying to sort out. I'm not sure the crossover points are dictated by anything more than the driver's response but I can say that IMO 1-4khz should be avoided if possible. That's not so say one can't use a single point at or below 1khz as Earl does. He has had great success with it with listeners reviews being off the charts. Crossing above 4khz would require a three way no doubt. In particular this is where my interest lies and I'll tell you why.....Ribbons. Both from an objective and subjective listening position, NOTHING outperforms a ribbon tweeter. But the limitations are clear with limited power handling and LF capabilities. My quest may be in vain where a line array is the only solution.......we'll see.
But what if 3kHz is a better cross over point for other reasons than sensitivity of the human hearing. Like most midranges would have to be used beyond their well behaved breakup free and wide dispersion region and could not be positioned close enough to the tweeter to give wide enough vertical lobing. You would be limited to very small 3" and 2" drivers with limited bandwidth and compromised performance overall.
I think if a crossover is well planned and carefully phased a small dip of 3dB in the measured power response at 3kHz instead of 5k is not that big a deal if audible at all. At least in normally furnished rooms with carpets on the floor.
I think if a crossover is well planned and carefully phased a small dip of 3dB in the measured power response at 3kHz instead of 5k is not that big a deal if audible at all. At least in normally furnished rooms with carpets on the floor.
The instantaneous thermal compression happens at all listening levels. I would not expect it to be a large effect for a woofer, but it might be audible. I would tend towards the larger voice coil just to be sure. I think that 5th Element is thinking of long term thermal compression where the motor structure heats up and the sensitivity drops. That's not the issue that I am concerned with. It is the sound modulation from the instantaneous changes in the coil from the signal. The larger the coil, the lower the modulation. I suspect that this effect has a lot to do with what some call "dynamics".
Earl, I don't know if you have seen this video about the JBL M2:
https://www.youtube.com/watch?v=CDmzfpf3fCk
Among many other interesting things Charles Sprinkle talks about the 15" woofer they used and how its VC material helped in reducing instantaneous resistance variations, and the effect on perceived dynamic. He also talks about the cone shape and material that prevent directivity to collapse too quickly after the crossover point (I think you faced that problem some times ago, and decided to use a bigger waveguide/smaller woofer).
All in all a very interesting video
https://www.youtube.com/watch?v=CDmzfpf3fCk
Among many other interesting things Charles Sprinkle talks about the 15" woofer they used and how its VC material helped in reducing instantaneous resistance variations, and the effect on perceived dynamic. He also talks about the cone shape and material that prevent directivity to collapse too quickly after the crossover point (I think you faced that problem some times ago, and decided to use a bigger waveguide/smaller woofer).
All in all a very interesting video
Yes, JBL has a patent on a VC wire material that has reduced changes in resistance with temperature. But, it turns out that adding about 10% nickel to copper gives you about 95% of the improvement that they get, at far lower cost. Of course that solution is not patentable since that material is well known.
The thing is that the resistivity vs. T isn't as big a factor as simply the thermal mass. The more copper in the VC the better. This has two positive effects, lower thermal modulation with current and lower current for a given SPL. Hence the thermal modulation drops with the square of the copper content - a more effective solution than a change in material.
It is nice to see this effect being recognized because I have been talking about this for more than a decade. I did my first measurements of this effect back in 2006.
I may look at that video, but marketing videos mostly just turn me off since reality is thrown out for hype.
Sean Olive recently took a lot of heat for his participation in a JBL video because the video was far from accurate.
PS. Sorry, could not get past the hype to watch the video to its limits.
The thing is that the resistivity vs. T isn't as big a factor as simply the thermal mass. The more copper in the VC the better. This has two positive effects, lower thermal modulation with current and lower current for a given SPL. Hence the thermal modulation drops with the square of the copper content - a more effective solution than a change in material.
It is nice to see this effect being recognized because I have been talking about this for more than a decade. I did my first measurements of this effect back in 2006.
I may look at that video, but marketing videos mostly just turn me off since reality is thrown out for hype.
Sean Olive recently took a lot of heat for his participation in a JBL video because the video was far from accurate.
PS. Sorry, could not get past the hype to watch the video to its limits.
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I really can't see how you think voice coil heating "instantaneous effect" is something missed by the audio engineering community, newly discovered by you
the understanding tempco of the wire, the "instant" heating with signal current is very old
regularly cited by those proposing/investigating current drive or needing to be dealt with in negative resistance "velocity feedback via back EMF" schemes
the understanding tempco of the wire, the "instant" heating with signal current is very old
regularly cited by those proposing/investigating current drive or needing to be dealt with in negative resistance "velocity feedback via back EMF" schemes
Here, in Serbia. Friend of mine bought Summa kit from a guy from US that bought it from you while it was still available. I can post the pics if you want. I even have a pics of throath area and xover schematic for 15TBX100/B&C DE250 combo but I would not post that in public because of respect for your work. But I can send it to you to see. Parts list is the same as the one you mentioned in one of your threads in "gedlee" subforum.
Why would I lie about something like that?
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