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Thread: Matching Drivers

  1. #1
    Administrator Robh3606's Avatar
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    Matching Drivers

    Just wondering if any of you have tried to match drivers into matched pairs?? Looking at Mr. Widgets F/R curves in the Ring Radiator Comparison thread there seems to be some variation within the groups of drivers tested. I have experimented with EQ in my active system and there seems to be a corelation between matching the curves closely say between 200Hz-8K or so and image stability. This to me seems to support the idea that a matched driver set could have advantages beyond uniform F/R with more stable imaging as a bonus. The low end and high end seem to have less affect its the midrange that seems to have the most effect. I was wondering what experiences you have had?? If you have tried to match drivers how did you do it.

    Thanks Rob

  2. #2
    Senior Member Lancer's Avatar
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    One reason people buy JBL components is because there is greater unit to unit consitency. If that isn't good enough and you want matched pairs send them back to JBL like Zilch did. See what happens... Another option is to buy a group and sift through them like people do with capacitors. Perhaps one can check with Westlake and see how they interact with JBL, TAD, etc.

    The low end and high end seem to have less affect its the midrange that seems to have the most effect.

    The high end definitely has an effect due to the plethora of overtones. If you can't hear the difference using a mismatched pair of, say, 066's then you're probably better off and won't need to spend a whole lot of money on hi-fi.

  3. #3
    Administrator Robh3606's Avatar
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    "The high end definitely has an effect due to the plethora of overtones."

    Hello Lancer

    By the midrange I meant the 200-8k range. The effect was strange especially if you unbalanced things on purpose like changing amplitude in the lower voice fundimental regions and leaving the top balanced. A center imaging vocal could be made to have the voice biased toward the right of left with the sibilance centered. Kind of disjointed things a bit. If you had speakers that had a bit of variation that were on either side of the spec I can see the imaging being pulled toward the louder source and if the loudness between the pair varies with frequency the imaging could also be hit or miss depending on the frequency content and the actual diferences between the speaker pair. Obviously there is more going on because of room interaction then just driver variability

    As far as I know JBL doesn't match pairs like the KEF did in the 70's. As long as the driver variation is not significant then the issue would be moot except for what the room will do.

    Rob

  4. #4
    Senior Member Lancer's Avatar
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    By the midrange I meant the 200-8k range.

    Right, which a high frequency driver like an 066 would cover whereas an 077 was not intended to do so. There was a wider variation in the older domes. The 035Ti has been real popular due to unit to unit consistency.

    As long as the driver variation is not significant then the issue would be moot except for what the room will do.

    It is probably best that everyone view it that way. That's one reason why people buy JBL transducers.

    Looking at Mr. Widgets F/R curves in the Ring Radiator Comparison thread there seems to be some variation within the groups of drivers tested.

    Yeah, it's fun for us to play around with measurement gear and get an idea of what's going. We're hobbyists. Obviously for any comparisons intended for professional publication purposes I'd recommend the measurement facilities at Harman Intl.

  5. #5
    Senior Member DavidF's Avatar
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    Matched components (speakers, coils, caps etc.) do matter especially as you move from high-quality sound over to high-end sound. Even in mid-to-high quality sound (in the home), matched components (caps, coils, etc. as well as drivers) may go further in providing the good sound as does spending more money on the very best caps, very best coils, and the like.

    It would take some amount of measurement accuracy to try this at home, though absolute calibration is not needed since you are looking at only deviation among the units. At one time, many of the D.Y.I. suppliers would sell matched drivers for an extra price. And, as pointed out, you may need several units to compare. I think you may still find that service, but more limited to high-end drivers. This seems contradictory to me in some ways, since, as Lancer says, it starts with very high production consistencies.

    I had problems with a first-round 4-way crossover design I am tweaking. In addition to issues with balancing vertically (matching response sensitivities) I had a persistent and annoying sense that the image was tilted off center. Very noticible with vocals since these are mostly centered in the mix. The image tended to float a bit as the image does when drivers are connected out of phase, and the image wander is effected by frequency. So, I thought this was a phase issue (which it may have been to an extent) and spent a lot of time retracing wire, checking polarity, thinking driver response variations, and alignment issues. Should have swapped the crossovers to begin with, as one simple way to determine the source of the problem by elimination. The problem moved with the swap. Rechecking the components I found that I installed a 22mF value cap instead of a 2.2mF on one side. This was a series component to the lower mid-range so the effect was to increase the low end side of this band-pass response curve. You could equate the effect of this component imbalance to a mismatch in frequency response between drivers. Though probably more significant in terms of typical production tolerance, it does point out how a mismatch can effect the response.

    DavidF


  6. #6
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by Lancer
    Looking at Mr. Widgets F/R curves in the Ring Radiator Comparison thread there seems to be some variation within the groups of drivers tested.

    Yeah, it's fun for us to play around with measurement gear and get an idea of what's going. We're hobbyists. Obviously for any comparisons intended for professional publication purposes I'd recommend the measurement facilities at Harman Intl.
    I agree that we do not have the facilities that are available to Harman International... really no one but Harman does. I also agree with criticisms made by several members that the information in those threads was not absolute or complete. That said, what was presented was quite accurate in as far as it goes.

    In defense of our Comparison Threads, we did see some clear anomalies in a pair of Zilch's drivers. After sending them back to the factory for a bit of rehab, they came back and measured beautifully and are now quite well matched.

    To get accurate measurements at home isn't inexpensive or easy, but I do think it is extremely eye opening and very useful, especially when dealing with older drivers that may no longer be what they once were.


    Widget

  7. #7
    Senior Member Lancer's Avatar
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    In defense of our Comparison Threads, we did see some clear anomalies in a pair of Zilch's drivers. After sending them back to the factory for a bit of rehab, they came back and measured beautifully and are now quite well matched.

    There are those who watch this site.

    I also agree with criticisms made by several members that the information in those threads was not absolute or complete. That said, what was presented was quite accurate in as far as it goes.

    I thought the whole thing was cool! Yeah, I would have liked all the data files and impedance curves, etc. but it was fine. There will be other opportunities. I wish more members would spend the cash for at least the WT2, if nothing else, so they could post such information as their own impedance curves, TS parameters, etc. It's fun!





    I think I'm pretty sure what precipitated this thread and I'm not real sure what I think about it yet.

  8. #8
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by Mr. Widget
    In defense of our Comparison Threads, we did see some clear anomalies in a pair of Zilch's drivers. After sending them back to the factory for a bit of rehab, they came back and measured beautifully and are now quite well matched.
    They sound mightily good, too!

    Mr. Widget's measurements revealed several instances where response is not well controlled. There are always design/manufacturing/material variables; some designs are inherently more consistent and stable than others.

    Mr. Widget and I observed that often in our testing. See, for example, chaos above 10 kHz in 243x drivers. JBL is apparently making improvements in that area however; each new pair that I test seems to be better matched.

    Another company that used JBL OEM is Meyer Sound, local here. They rebuilt/enhanced drivers to their own specifications, allegedly, until they were able to build them completely in-house.

    The used vintage drivers we all love can often be mismatched, of course. Some level of testing should be employed when incorporating them into systems. Sophisticated equipment is not necessary for that. Something as simple as an SPL meter and tone disk will work; the results don't have to be absolute, as DavidF indicates above.

    New diaphragms in everything isn't always the optimum approach, either, unless they are themselves subsequently verified with measurements.

  9. #9
    Senior Member Lancer's Avatar
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    New diaphragms in everything isn't always the optimum approach, either, unless they are themselves subsequently verified with measurements.

    That is correct, hence the JBL Authorized Service Center.
    Faulty recone and diaphragm kits are returned to JBL.

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    I wonder what Unwound, I mean Edgwound has to say about this?

    What is the faulty or failure rate on change outs?

    Perhaps it comes down to the skill of the reconer.

    Speaking of change outs I still piss myself laughing about Boputnam trying to fit an oval port in a round hole of an Alpine car sub. I hope they never offer him an Installer license....

    Ian

  11. #11
    Senior Member edgewound's Avatar
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    Unwound?

    Hey Ian...how did you know how my day was going? are you psychic?

    The skill of the technician has alot to do with how the finished product sounds because we are trained to look for certain anomalies that might occur in the part...and sometimes we can fix it and sometimes we can't....like Lancer said defective cone kits/diaphragms go back to JBL.

    A properly repaired driver...any driver...is every bit as good as a brand new unit...because basically, it is returned to new....sometimes improved specs.

    If a driver isn't prepped properly for repair,and done meticulously it's destined to repeatedly fail...sometimes the repaired driver is better than when it came off the assembly line because it should be receiving more attentive care.

    Then there's the issue of pilot error..DJ's are notorious for running this stuff into the ground...that'll piss some people off...I know Scotty knows better .

    Edgewound

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    Thanks Edgewound,

    Have a great weekend.

    Ian

  13. #13
    Senior Member edgewound's Avatar
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    You're most welcome, Ian....time to tip a few because it's been hotter'an hell here in socal...but...seems like it is most everywhere...our earth is angry .


    Edgewound

  14. #14
    Administrator Robh3606's Avatar
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    Hey Edgewound

    I am sweltering here in NY! Here's one to yah!

    Rob

  15. #15
    Senior Member louped garouv's Avatar
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    Quote Originally Posted by edgewound
    You're most welcome, Ian....time to tip a few because it's been hotter'an hell here in socal...but...seems like it is most everywhere...our earth is angry .


    Edgewound
    been hotter than ever was recorded (think the first were like 1890 or thereabout) on the Western Slope of Colorado (Grand Junction) this past week.... forget what the temp/ was though

    Denver hotter than since I've lived here, but that,s not too long.....



    so beyond a basic SPL meter, what other budget measurements would be easily/cheaply implemented by an utter idiot DJ?


    all of you guys are deep, sometimes I am just blown away by the audiotalk....

    then theres the timess that I chime in.....

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