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Thread: JBL Performance Series

  1. #1591
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    PT250 words of caution

    As a general exercise, grumpy and I both feel that this would be far more work and expense than it's worth. If you've got all the parts and the necessary testing gear, then why not?

    This is really a sum of its parts achievement. Here's a cost break down:

    1. L250 pair $650 and a 100 mile round trip
    2. PT800 pair for parts $250 pus shipping
    3. three hafler SR2300 amps from the Hafler closing $1200 plus shipping
    4. one Hafler SR2600 amp from the Hafler closing $550 plus shipping
    5. 240Ti pair donor of 044Ti and Le14H-1 pairs $450 local pick up
    6. BSS 366T units $800 plus 80 mile round trip
    7. Niles IPC12 $250 plus shipping
    8. Denon DVD2900 barter
    9. Citation 5.0 $650 plus 50 mile round trip
    10. XLR cables $100 plus shipping


    That's just shy of $5000 at my accumulated costs. Just the BSS 366T Omnidrive units themselves would be more than that at street prices today. Of course that doesn't count the cost of grumpy's test gear, his time and effort, his considerable travel, or the value of the avocados he brought.

    Bottom line is we cannot simply drop in some Performance Series drivers and call it good. This is a true 4-way, active quad-amped system, and it's not cheap or simple. It is however, very cool, and I hope someday we get it right up to its real potential.

    I want to particularly give thanks to grumpy who served as Virgil to my Dante on this journey. http://users.erols.com/antos/dante/divine_com.html He went way above and beyond in this project, and I would have effed it up many times over without his calm and thorough approach. Dude!
    Out.

  2. #1592
    80sKid
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    I certainly understand and in your shoes, I too would be anxious to fire them up and start listening.

  3. #1593
    Senior Member rdgrimes's Avatar
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    Quote Originally Posted by Titanium Dome View Post
    Bottom line is we cannot simply drop in some Performance Series drivers and call it good. This is a true 4-way, active quad-amped system, and it's not cheap or simple. It is however, very cool, and I hope someday we get it right up to its real potential.
    I wonder what the comparative cost would be with a custom built passive XO and a single big-assed amp to drive them? Seems like a modified 250ti XO would be quite doable? So if someone started with a pair of 250ti, the costs would only be for 4 drivers and XO work.

    While your project is great, it may not be representative of what is actually needed to build a very decent PS250.

  4. #1594
    Senior Member grumpy's Avatar
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    Virgil and Dante?
    How about Beetle Bailey and Dagwood
    (thanks for the kind words)

    ...and sure, once a finished design was implemented
    passively, one could reproduce it with less expense.
    Step 1, find someone interested with the knowledge,
    experience, and proper tools to do so. This was just
    fun... That sounds like real work... and to Beetle
    Bailey, well, you get the picture.

    I'll post some plots when I fire up my computer.

  5. #1595
    80sKid
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    One has to wonder if the PS250/PT250's sonic edge would diminish with a passive design. It could be that a considerable part of its sonic splendor comes from the active design and the multitude of amps.

  6. #1596
    Senior Member grumpy's Avatar
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    swept sine in-room response, and current crossover as measured
    (ignore the rising levels below each crossover frequency and anything
    below 30-40Hz)

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    A much more (probably over) corrected crossover/EQ was
    implemented weeks earlier, but figured it was better to keep it simple
    at first, then work on time alignment (not explicitly done), and further
    adjustments at a later date.

    Amplifiers were all set at a nominal (easy to return to) setting
    then slightly bumped during listening... more as tone controls
    than anything... no one wants to listen to a truly flat system
    at home.

    No hiss (without putting my ear inches from the tweeter)
    and no hum (after grounding metal shell on the RCA/XLR adapter).

  7. #1597
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    Quote Originally Posted by 80sKid View Post
    One has to wonder if the PS250/PT250's sonic edge would diminish with a passive design. It could be that a considerable part of its sonic splendor comes from the active design and the multitude of amps.
    I'd put forth that the active crossovers and (over)amping design are the main contributors. Certainly a stock L250 complement of drivers would sound better if given the same treatment.

    Nonetheless, the 044Ti, 904Ti, and 908Ti are better drivers and impart a superior sound, so they contribute as well.
    Out.

  8. #1598
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    Just being a little AR here...

    Quote Originally Posted by rdgrimes View Post
    a very decent PS250.
    Quote Originally Posted by 80sKid View Post
    the PS250/PT250's .
    Performance Tower = PT800
    Performance Center = PC600
    Performance Subwoofer = PS1400

    Therefore, I'm calling this the PT250 based on its PT800 and L250 roots.
    Out.

  9. #1599
    Senior Member grumpy's Avatar
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    More 'PT250' implementation info:
    (individual driver EQ, and nominal pre-EQ crossover)

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    This is just to semi-document the process... the EQ settings were
    determined while the system was on it's back in a garage... and
    based on individually measured driver responses (w/o crossover).

    I'm a bit surprised they carried to a standing system in another
    environment as well as they did.

  10. #1600
    Senior Member JBLnsince1959's Avatar
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    Dome.. how does the sound compare to a PT800 and PS1400 stacked together

  11. #1601
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    Quote Originally Posted by JBLnsince1959 View Post
    Dome.. how does the sound compare to a PT800 and PS1400 stacked together
    That's hard to say. Even though I have both, they're in different rooms in different kinds of systems.

    My four PS1400/PT800 stacks are part of a 5.1 surround system in a 32x32 open space with ceilings from 8' to 24' or more. The PT250s are a simple stereo set up in a 14.5x15.5x11.5 room.

    The PS1400/PT800 is bi-amped, I suppose, due to the PS1400 having its own 400W amp, but everything else runs through passive crossovers at 125W/ch, unbalanced. The PT250 has active crossovers and 300W/ch for each of the top three drivers (that's 3x300 per side) and 600W/ch for the woofers, balanced.

    That's a stark difference.

    With those disclaimers, it's pretty clear to me that the LE14H-1s work better in the L250 enclosure than the LE14H-3s work in the PS1400 enclosure. They stretch out more and have a deeper reach. The extra cabinet volume is quite a benefit, as others have noted in their home-built cabs.

    The 908Ti and 904Ti work very well. Though we have some more tweaking to do, I really like the way they sound in the L250 enclosure. It's not the cabinet volume, as they're in doghouses; it's the baffle shape and slope. They seem to be in even better harmony that when in the octagonal PT800 enclosure.

    The 044Ti seems a bit hot to me. We've seen a few little anomalies with it that might not be present with the TM025. I'll keep looking for a resource to make a mounting plate for it, so we at least can swap it in to see if there's a difference.

    The PS1400/PT800 combo is still the bang for the buck leader here, but I have to say that the PT250 is better in many important ways already, and a little more tweaking and a tweeter/waveguide swap may widen the gap even more.

    **I'm not likely to carry a couple of stacks down to the music room or the PT250s up to the main level, so a direct comparison is not in the foreseeable future.**
    Out.

  12. #1602
    Senior Member grumpy's Avatar
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    Funny... now that I think about it, that EQ shown above (in the tweeter range) was
    for the TM025 ... no wonder we turned that amp down a bit (the 044Ti not really
    being assisted efficiency-wise by a wave guide the way the TM025 is).

    The FR shown above (#1595) was with the amp attenuator dropped ~5-6dB after an initial FR
    sweep plot showed the tweeter level was 'a bit' hot. On-axis, the two tweeters are pretty
    flat in their intended range (which is why the level adjustment at the amp worked as well
    as it did). This should get fixed in the BSS config so that the nominal amp settings are
    back to a standard value for this system.

    ... Looking back at comparative PT800 measurements made in the same garage and location
    as the proto-PT250 drivers/cab, the PT800 did seem to have both a slight/wide presence peak
    (compared to the EQ'd TM025 in the PT250) and a more extended response... something
    I'd like to look at next time I'm over (check to see what's causing the high end rolloff with
    the 044Ti ... that -measured- response rolls off too regularly and quickly for me to accept it
    as fact).

  13. #1603
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    PS1400 Amp

    Anyone know where I can purchase just the Amp for the PS1400?

  14. #1604
    Senior Member grumpy's Avatar
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    I'd suggest a query in the "Marketplace" sub-forum, but no... unless you hit it lucky
    on eBay, I would expect that a repair/replacement via JBL would be your only source
    without resorting to an aftermarket replacement, or buying a whole sub. I say 'lucky'
    on eBay as the amp (in my narrow view) seems to have been the weak link so parted
    out units would likely -not- include a working amp. If you -are- able to get a unit or two
    to part out, I know folks who might be interested in the LE14H-3's and trim rings

  15. #1605
    Senior Member rdgrimes's Avatar
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    Quote Originally Posted by maabx View Post
    Anyone know where I can purchase just the Amp for the PS1400?
    I would think that repairing rather than replacing is the only real option.

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