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Thread: Truextent Diaphragms in JBL four-inch compression drivers

  1. #16
    Senior Member Ian Mackenzie's Avatar
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    I will try and find the schematic. Its a lot simpler then you might imagine.

    Yuichi also has a 1.5 to 2 inch adapter for using 1.5 inch drivers (people with Tad 4003s are not complaining..except for the price)

    What you have measured about these alternative Be diapgragms is consistant with what I have been advise by company that uses Truextent diaphragms in field coil compression drivers with a Tractrix horn, hence they use a Be super horn tweeter above 16 khertz. The tractrix horns are apparently subjectively better then the Tad 4001 horn but you need a super tweeter.

    So don't throw out your 2405s yet.

    I am inclined to think the 0476 with the bi radial is still the winner.

    What this means is as usual there is no free lunch but you can have fun making it work.

    The notion of a flat response to 20 khertz is more important on paper to the Japanese than it is subjectively anyways provided the diaphragm is not in breakup mode too early.

    A gentle tappering off above 10 khertz can be a good thing in some situations

    I think Greg has mentioned this before.

    By the way I got some complaints from the local natives attempting to run a series external ground plane measurements with LMS. 2.83 volts at 110db sensitivity above 10 khertz is freakin loud if you are a dog I guess.

    Ian

  2. #17
    Senior Member cooky1257's Avatar
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    That's a shed load of work for the benefit and enlightenment of us all.
    Thank you.
    Anyone tried a Yuichi 290 with a 3" Be driver?.....Doh! thanks Ian.

  3. #18
    Administrator Robh3606's Avatar
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    Hello 4313B

    Thanks for measuring and posting all those measurements.

    Rob
    "I could be arguing in my spare time"

  4. #19
    Unabashed Speakerholic cosmos's Avatar
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    Thanks 4313B for doing these measurements. As it turns out, I am even more glad as you uncovered and resolved a couple problems as well. I can't thank you enough for that!

    If I am interpreting this correctly, the FR looks very similar to the stock Titanium diaphragms they are meant to replace. That is probably a good thing in some respects as it allows a similar compensation scheme and at the same time offers significantly improved quality of sound.

    Ian, I am looking forward to seeing the schematic of the TAD compensation circuit. In addition, I'd really like to see any other adaptable compensation networks. Getting reasonably flat to 18KHz without a tweeter and with this quality sound would be a dream come true for me. I've heard these drivers with the TrueXtents and they sound great to me.. besides, I already own them..

    476Be would very likely be a better driver, (I have never heard them) but these are reasonably priced and readily available.

    Now, I really wonder how TAD TD-4001 would measure in the same setup.

    In any case, Thank you again for your time and help!

  5. #20
    Member originaltubino's Avatar
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    Quote Originally Posted by cosmos View Post
    476Be would very likely be a better driver, (I have never heard them) but these are reasonably priced and readily available.
    Claude Rains(Louis):The waters? What waters? We're in the desert.
    Humphrey Bogart (Rick): I was misinformed.


    Quote Originally Posted by cosmos View Post
    Now, I really wonder how TAD TD-4001 would measure in the same setup.
    Me too, and with the compensation scheme Ian mentions.

    That's the problem with generous competence. It only gets you more work requests!
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  6. #21
    Senior Member spkrman57's Avatar
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    Thank you 4313B for the time spent on this project!

    First off I would like to point out that the 350hz Edgarhorns are mine and are the ones in my avatar.

    I had tried some EV DH1A compression drivers on them in the past. Dan (Cosmos) also heard them when he visited me before. We both agreed the HF extension was decent enough(passive crossover @ 800hz using passive attenuation/EQ), but the "simbilance" or what I call the "titanium sound" was readily evident.

    I plan to use a 4-Pi (Wayne Parham) 1.6khz crossover w/JBL 2226J's on the bottom end w/JBL 2446 compression driver equipped with Be diaphrams as soon as I can afford to make that happen!

    I see with the 2446/Be/Edgarhorn plots that the 1.6 khz region looks to be fairly flat response wise. I don't know enough to extrapolate all the info here so I'm actually speculating!

    Thanks a million for the help 4313B!!!

    Regards, Ron

    PS: Did my e-mail with the att/EQ chart help show what Wayne is trying to do with his crossovers?
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  7. #22
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    Quote Originally Posted by cosmos View Post
    If I am interpreting this correctly, the FR looks very similar to the stock Titanium diaphragms they are meant to replace. That is probably a good thing in some respects as it allows a similar compensation scheme and at the same time offers significantly improved quality of sound.
    Yeah. I did measure the 2421B, 2441, 2445 with Truextent, and the 2446H (before I started swapping diaphragms and cores) with the stock 4344/4345 network last Sunday and none of the 4-inch drivers are a bolt-in without tweaking the network (or using EQ like Bo does).

    As far as compensation schemes, I was thinking about trying to put together one of Wayne Parham's real quick as per Ron's email to everyone. I'm not sure I will get to it today though.
    Quote Originally Posted by spkrman57 View Post
    First off I would like to point out that the 350hz Edgarhorns are mine and are the ones in my avatar.
    Quote Originally Posted by spkrman57 View Post
    I plan to use a 4-Pi (Wayne Parham) 1.6khz crossover w/JBL 2226J's on the bottom end w/JBL 2446 compression driver equipped with Be diaphrams as soon as I can afford to make that happen!
    Send me some values so I can see what I have around and I'll measure the results if possible before all this has to be returned.
    Quote Originally Posted by spkrman57 View Post
    I see with the 2446/Be/Edgarhorn plots that the 1.6 khz region looks to be fairly flat response wise.
    I'd have to look at the raw data again to confirm that. These are half octave plots without all the warts. They're good for trend analysis. We'd have to look at the rough stuff while actually building any networks.
    Quote Originally Posted by spkrman57 View Post
    PS: Did my e-mail with the att/EQ chart help show what Wayne is trying to do with his crossovers?
    Yes. But give me some values for your application. I don't want to have to figure anything out right now. Just toss me some values.

  8. #23
    Senior Member eso's Avatar
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    Quote Originally Posted by spkrman57 View Post
    First off I would like to point out that the 350hz Edgarhorns are mine ..
    I'm curious about where the Yuichi's came from. There's not many of those floating around and I just sold my old pair to a buyer in Ohio...

    Do they look like this:





    eso

  9. #24
    Senior Member spkrman57's Avatar
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    Here's some quick values to try out for 16 ohm diaphrams

    Using my chart on the e-mail I sent out:

    R2 20 ohms
    R1 60 ohms
    C1 .2 ufd

    This is for approx 15 db attenuation/EQ on a 1.6 khz crossover which is the closest I can find for the difference between the JBL 2226 @ 97.4 db/watt and the JBL 2446 @ 112 db/watt if I have the information correct.

    The crossover I plan to use is the one I sent you the schematic of. I adjusted the values to reflect the 16 ohm LF and HF drivers I'm using (ie: 2 x coil/resistor values and .5 x cap values).

    My application is for passive crossover vs the active bi-amping that Rick, Brad and Dan are going to use.

    Thanks again 4313B!

    Regards, Ron
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  10. #25
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    Quote Originally Posted by eso View Post
    I'm curious about where the Yuichi's came from. There's not many of those floating around and I just sold my old pair to a buyer in Ohio...

    Do they look like this: (see pic in post 23)

    eso
    They look exactly like those - They are in fact - Those!!!
    Brad

  11. #26
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by 4313B View Post
    I'd have to look at the raw data again to confirm that. These are half octave plots without all the warts. They're good for trend analysis.
    I was curious about the mass break point of the Truextent diaphragms... I assume it was clearly visible in the unfiltered plots? With the mylar surrounds I expect the resonant peak is better damped than it would be with a simple roll suspension.


    As others have posted... thanks for slogging through this. It was interesting and helpful. I have done a few projects like this and it is surprisingly more effort than most would expect.


    Widget

  12. #27
    Senior Member eso's Avatar
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    Quote Originally Posted by Dingusboy View Post
    They look exactly like those - They are in fact - Those!!!
    Brad
    It's good to know they are being well used... I wanted them to go to a good home.

    Here's one of my new little experiments for Urei duplex monitors:




    Aren't those just the cutest little radial horns ever?

    Brad, do you know if the TrueXtent diaphrams are available for 2425H drivers (8ohm)?

    BTW, The plots do show how much nice the Yuichi response is down at 500Hz. The 350 Tracs begin rolling off above that. The trade-off is that the Tracs produce a more 3 dimensional image. The Yuichi's image well left to right, but they do not reproduce the depth of the soundstage as well.

    Lots of work in those tests. Thanks.

    eso

  13. #28
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by eso View Post
    BTW, The plots do show how much nice the Yuichi response is down at 500Hz. The 350 Tracs begin rolling off above that. The trade-off is that the Tracs produce a more 3 dimensional image. The Yuichi's image well left to right, but they do not reproduce the depth of the soundstage as well.
    I've mentioned this before... some consider it a Hi-Fi effect, but I certainly enjoy the effect when well done.

    Did you consider making mini tractrix horns for the Ureis?


    Widget

  14. #29
    Senior Member eso's Avatar
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    I've considered it, but the image issue between the Yuichis and the salad bowls is more due to the vanes in those radials, not unlike the effect of multicells.

    With the Ureis I'm starting with pretty straightforward reverse engineering before making global changes. The crossovers are designed with correction for the horn and driver. Changing either will mean a major crossover redesign and I'm a wood butcher, not an electronics engineer...


    eso

  15. #30
    Member originaltubino's Avatar
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    Quote Originally Posted by eso View Post
    I've considered it, but the image issue between the Yuichis and the salad bowls is more due to the vanes in those radials, not unlike the effect of multicells.
    I noticed that Mr. Yuichi has published plans for a vaneless or finless 290hz horn, called A-290FL, linked from this page:

    http://www.geocities.jp/arai401204/H..._Speakers.html

    I have the A-290S and love it, but I have heard Cosmos' new tractrix and been impressed with the 3D imaging. I think it's a real retrieval of recorded information -- on good recordings. It sure SEEMS real on live-recorded music, e.g. Mapleshade stuff.
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