Zilch's AK Design Collaborative - Econowave Speaker

[Zilch]

I was using the 8-ohm woofer XO, for my "8-Ohm" rated JBL 123A-1s. Well, they're specified with an Re of 4.4 or so. Maybe I needed to use the 4-ohm type.

It's virtually a given that the lowpass should be tweaked for optimum performance with E'Wave.

Re is the DC resistance, not the impedance, so your assumptions may not be valid. I just measured a pair, in closed boxes, and the actual impedances at our nominal crossover frequency of 1.6 kHz are 9.6243 and 9.4090 Ohms. A "correct" Zobel has the potential of lowering that to ~5.0 Ohms, looks like:

Did you see my earlier post on this subject:

http://audiokarma.org/forums/showthread.php?p=2266540&highlight=123A-1#post2266540

I have not yet verified those values, but it appears that we have arrived at nearly the same place.

Note also that 123A-1 is a positive polarity woofer, a JBL rarity, so the Selenium polarity should be reversed per the standard E'Wave schematic.... :yes:

 

[Zilch]

Don't you have Bass Box Pro?? They have both drivers loaded so set them up for 100 watts or what have you and you can see the differences up top.

Yes, Rob, but that doesn't tell us if 2234H is more "articulate" up there than 2235H.

Rob, is that plot for the 2231?

Rob's talking about 2234H. The data sheet for 2231 may be found via the link Rob posted at #3373; it's called 2231A there.... :thmbsp:

 

[publius]

AHH, thanks!

The only one I've found, that looks like a "real" measurement is that one for the 4647.
(Meaning detailed/better resolution showing dips/peaks and what not)
http://www.jblpro.com/pub/obsolete/4647.pdf

the 2225h measurement is also shown in the jbl white paper on vented gap cooling.

http://www.jblpro.com/pub/technote/tn_v1n18.pdf

power compression data are also shown in the paper, but not impedance or off-axis response.

 

[publius]

The altec cone profile, minimal inductance and big chrome dildo do wonders in on and off axis response.

let me kick out a hypothesis...

while janowitz touts the off axis performance of the td drivers and it appears to be confirmed in the 45 degree off axis measurement, this may be an illusion.

the off-axis control must be taken as the *difference* between the on-axis and the off-axis measurements. the td15x has a 5db bump in frequency from 1000hz to about 1400hz or so, the region where most 15's are down 6db. the result is that the off-axis appears not to fall as fast as most other 15" drivers that don't have this same 5db bump. when controlling for this, the td series don't seem to hold pattern any better than most other good 15's. the same off-axis performance could be eq'd into other 15" drivers, but then this would give a bump in the on-axis response.

 

[publius]

Publius would like those distortion curves at 130 dB there, my guess.... :tongue:

hey now. a little headroom never hurt anybody. :yes:

the 2225h models quite similarly to the 2226h, but the 2226h has less power compression and less distortion. and while i am not sure of all the ramifications, the ts qms is 5 on the 2226h and 2.5 on the 2225h. the trend to increasing qms is also an evolution that i have noticed in the le14h-1 to le14h-3. i have only found one mention anywhere about qms and it was that hi fi drivers tend toward lower qms in order to try to flatten frequency response, while higher qms provide for more a open, detailed sound. and while looking at a singular metric never tells the whole story, qms on the 1500al is 12.7. so, considering all this, i would choose the 2226h over the 2225h. that said, neither of those drivers is going to have great bass extension without some eq in the way that the le14h-3 or the 2235h will.

 

[publius]

Hello Zilch

Don't you have Bass Box Pro?? They have both drivers loaded so set them up for 100 watts or what have you and you can see the differences up top. You get more output but it doesn't look like it extends much higher. It's the exact same cone so off axis I would think should be identicle to a 2235 with a bit more juice up top.

Rob

just a heads-up rob...using thiele small parameters, driver/enclosure performance is only reliable up to about 200hz. non-linear effects cause many drivers to model with a falling frequency response starting around 200hz or so, when in reality, they may have flat to rising response.

 

[Zilch]

With its high power-handling capacity, 2226H can certainly be used in assisted alignments. I've never tried that, but others have even designed subs using them.... :yes:

 

[Kegger]

Hey thanks for that, basically confirms the 4647 graph, only 2 "real" differences are the
blip or bump at 1K and that the 115spl one is a sealed cabinet so hence the bass rolloff.
(5ft cab tuned to 40hz should give pretty good 40hz performance, according to the specs)

the 2225h measurement is also shown in the jbl white paper on vented gap cooling.

http://www.jblpro.com/pub/technote/tn_v1n18.pdf

power compression data are also shown in the paper, but not impedance or off-axis response.

 

[publius]

With its high power-handling capacity, 2226H can certainly be used in assisted alignments. I've never tried that, but others have even designed subs using them.... :yes:

an interesting thing here is that the 2226h is about 4db more efficient overall than the 2235h and only needs about 4db of "boost" in the bass to have the same frequency response. the net effect is that the 2226h requires the same amount of power for the same amount of bass spl as the 2235h. :thmbsp:

with parametric eq capability, there wouldn't seem to be any reason to use the 2235h. unless of course, one doesn't "believe" in using eq.

 

[dnewma04]

We are collectively a bunch of audiophiles who have been taught to resent and even loathe EQ. It is the devil incarnate. Therefore, I will be absolutely using EQ.

 

[Russellc]

We are collectively a bunch of audiophiles who have been taught to resent and even loathe EQ. It is the devil incarnate. Therefore, I will be absolutely using EQ.

Obviously, JBL thought it made sense to have both.

Kegger, 2225H in 5 cu ft tuned to 40 hz works great, thats what 4647 is. The "messiness" around 900 hz @ 45 degrees isnt too noticeable, infact, I thought it slightly cleaner than the 2235H. ( In normal listening )

Russellc

 

[KCM]

Progress Report

I mentioned E-Waving a pair of NLA's, and planning to try it on my Model 19's here-ish: http://www.audiokarma.org/forums/showthread.php?t=150939&page=208

I was not pleased with the Altec conversion. It sounded big, smooth, dynamic, but I'm thinking maybe the wide driver spacing is not optimum. It just didn't sound as coherent as the E-Waved Advent's.

I am planning the next phase with a pair of JBL 123A-1 woofers. I have done some searching and see that a 3 cu ft sealed enclosure should work, but what about adding a aperiodic vent like this ? : http://www.troelsgravesen.dk/JBL_L100_08.htm

I also purchased a pair of Selenium D220Ti drivers and the <95 db woofer passive crossover components to get a baseline of what you guys are hearing compared to what I've been listening to with my Radian drivers and Behringer DCX-2496 active crossover. I've tried additional combinations with these components: Seleniums with the active crossover, Radians with the passive and the general characteristics remain. The Selenium drivers sound brighter/splashier/more metallic. The Radians are warmer and more open sounding. Also, the Radians have a more distant soundstage whereas the Seleniums are more forward. The Seleniums have much greater perceived high frequency energy even when both measure similarly For the moment, I prefer the Radians. I also prefer the active crossover, better clarity and dynamics.

 

[Zilch]

I am planning the next phase with a pair of JBL 123A-1 woofers. I have done some searching and see that a 3 cu ft sealed enclosure should work, but what about adding a aperiodic vent like this ? : http://www.troelsgravesen.dk/JBL_L100_08.htm

Best I can determine, the aperiodic vent merely lowers the impedance at resonance. It's equivalent to a leaky closed box, and does not maintain the air spring to limit the excursion, and thus, has limited advantage.

I also purchased a pair of Selenium D220Ti drivers and the <95 db woofer passive crossover components to get a baseline of what you guys are hearing compared to what I've been listening to with my Radian drivers and Behringer DCX-2496 active crossover. I've tried additional combinations with these components: Seleniums with the active crossover, Radians with the passive and the general characteristics remain. The Selenium drivers sound brighter/splashier/more metallic. The Radians are warmer and more open sounding. Also, the Radians have a more distant soundstage whereas the Seleniums are more forward. The Seleniums have much greater perceived high frequency energy even when both measure similarly For the moment, I prefer the Radians. I also prefer the active crossover, better clarity and dynamics.

I assume you've worked up the requisite HF comp using the DCX-2496 and response measurements?

Radians are aluminum, as I recall, which inherently has more damping than titanium, and a "warmer" sonic character. Same happens when you swap diaphragms in LE-85, for example.... :yes:

 

[dnewma04]

Best I can determine, the aperiodic vent merely lowers the impedance at resonance. It's equivalent to a leaky closed box, and does not maintain the air spring to limit the excursion, and thus, has limited advantage.

Correct, and a leaky closed box is effectively a larger sealed box. I guess there could be considered two advantages.
1.) You can use a smaller box while attaining the same system Q.
2.) You can "tune" (to a limited degree) a sealed box to taste without resorting to making new enclosures.

 

[Zilch]

with parametric eq capability, there wouldn't seem to be any reason to use the 2235h. unless of course, one doesn't "believe" in using eq.

JBL provided assist in BX63(A) for use with 2235H in B380 (that Timbers guy, again,) and many sub plate amps now have adjustable VLF boost built in.

BX63A is a really simple DIY build, and it's eminently tweakable.... :thmbsp:

http://manuals.harman.com/JBL/HOM/Technical Sheet/BX63A ts.pdf

 

[Russellc]

JBL provided assist in BX63(A) for use with 2235H in B380 (that Timbers guy, again,) and many sub plate amps now have adjustable VLF boost built in.

BX63A is a really simple DIY build, and it's eminently tweakable.... :thmbsp:

http://manuals.harman.com/JBL/HOM/Technical Sheet/BX63A ts.pdf

Interesting.:yes: I for one, am all ears. Very interesting indeed.

Russellc:thmbsp:

 

[Robh3606]

Yes, Rob, but that doesn't tell us if 2234H is more "articulate" up there than 2235H.

Hello Zilch

Well you know your right it just shows the change in Fs, and sensitivity which is what you would expect. It's the exact same cone and its a mass ring not a coating of Aquaplas so I doubt there is any real difference up top asside from the added sensitivity. Get more useable X-maz as well, no mass ring to ring.

Have you ever compared a 4430-4435 that's about the only way to see if you hear any differences where the horn cross's over.

Rob

 

[Zilch]

Have you ever compared a 4430-4435 that's about the only way to see if you hear any differences where the horn cross's over.

I believe we know from your (and others') work that a quality midbass driver does a better job in the 500Hz - 1 kHz region; it's the two-way vs. three-way thing.

I'll have to pull or make some 2234Hs myself to hear if there's any difference between them and 2235H there. The difference being just the mass ring, perhaps not....

 

[KCM]

Best I can determine, the aperiodic vent merely lowers the impedance at resonance. It's equivalent to a leaky closed box, and does not maintain the air spring to limit the excursion, and thus, has limited advantage.

I assume you've worked up the requisite HF comp using the DCX-2496 and response measurements?

Radians are aluminum, as I recall, which inherently has more damping than titanium, and a "warmer" sonic character. Same happens when you swap diaphragms in LE-85, for example.... :yes:

Thank you ! I will plan to build a sealed enclosure, then.

I have gotten the response to be as flat as possible with level matching, crossover points and slopes, then parametric EQ to improve that, concentrating on reducing peaks more than increasing dips and also limiting the severity of my adjustments because it seems to do more harm than good at some point. However, this has not resulted in a gradual 6db/octave increase above 3-4k as I've read should be applied. I'm going from memory, but I think without EQ I measured a pretty good peak around 3-4k, then a big dip to about 12k, then it's pretty flat again to about 18k. I'm using TrueRTA with a DBX measurement mic.

Yes, the Radians are aluminum with mylar surround.

 

[Russellc]

I mentioned E-Waving a pair of NLA's, and planning to try it on my Model 19's here-ish: http://www.audiokarma.org/forums/showthread.php?t=150939&page=208

I was not pleased with the Altec conversion. It sounded big, smooth, dynamic, but I'm thinking maybe the wide driver spacing is not optimum. It just didn't sound as coherent as the E-Waved Advent's.

I am planning the next phase with a pair of JBL 123A-1 woofers. I have done some searching and see that a 3 cu ft sealed enclosure should work, but what about adding a aperiodic vent like this ? : http://www.troelsgravesen.dk/JBL_L100_08.htm

I also purchased a pair of Selenium D220Ti drivers and the <95 db woofer passive crossover components to get a baseline of what you guys are hearing compared to what I've been listening to with my Radian drivers and Behringer DCX-2496 active crossover. I've tried additional combinations with these components: Seleniums with the active crossover, Radians with the passive and the general characteristics remain. The Selenium drivers sound brighter/splashier/more metallic. The Radians are warmer and more open sounding. Also, the Radians have a more distant soundstage whereas the Seleniums are more forward. The Seleniums have much greater perceived high frequency energy even when both measure similarly For the moment, I prefer the Radians. I also prefer the active crossover, better clarity and dynamics.

Strange, you modification to the Model 19 altec greatly interested me. when I first had the wave guides, I screwed a JBL 2425 ( b/c I had them and no Seleniums at the time ) onto the wave guide and tried them on top of my altec A7s. It actually worked better than I expected, even though the crossover was no the Econowave crossover. You might try reversing the phase of the HF hookups and see if this helps.

The driver spacing may have something to do with it, but I would check all the wiring and make sure nothing got mixed up. I really thought that combination would work well. I know zilch has cloned that crossover and tried it in a few Econo wave like speakers in other threads, and had good results. Interested to hear how the proper (>95 db ) would sound, good luck with the project. Zilch may have some answers for you beyond what I have offered, I really think that combo could rock.

Russellc