Sonic difference between non PX vs PX panels

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  • #257
    hpfish10
    Participant

    I have the A1 non PX speakers, I am happy with the sound but wondering what is the sonic difference if I upgrade to the PX technology. Thanks

    #258
    TWB
    Moderator

    The introduction of the PX series was a major redesign of the internal structure of the panel to greatly strengthen it, as well as a switch-over to a better stator wire and insulation which addressed a weakness that led to far too frequent panel failures which necessitated a return of the panel to the factory. Since then ‘arcing over’ and the resulting burn holes in the membrane has become a rarity, eliminating a problem that resulted in a reputation for poor reliability. If your non PX panels are still working well, it’s most likely they have not been moved and subjected to the stress of handling. Today’s panels are significantly stronger and more reliable.

    The subsequent improvements in sonics have mainly come with the introduction of better toroidal transformers and better capacitors, all included in the “Consumate” backplates and lastly the Bass Focus redesign of the panels which improves the bass response. Older backplates can be updated, pre PX panels can not; they need to be replaced.

    #260
    hpfish10
    Participant

    I have toroidal backplates and if my non px panels are still ok, based on your response going to the px should not give me better sound.
    I notice amplifier plays a major role in improving SQ though.

    #261
    TWB
    Moderator

    If you have the Toroidal II transformers, you are almost all the way to the Consummate. I don’t think you would gain much by going to the PX panels. Yes, the amplifiers play a major role in making Sound Labs perform to their potential. And, being highly resolving, everything else up stream is very important too. The best source, preamp, clean power, and vibration control under your electronics. I firmly believe the use of Stillpoints has enhanced my system. And don’t underestimate the importance of the acoustics of your room.

    #263
    bk12
    Participant

    There were many generations of Pre-PX panels. The durability and quality of the sound is different between them.

    At least a few versions that I can think of:
    -Wooden construction with equally spaced horizontal ribs (original A-1)
    -Plastic construction with equally spaced horizontal ribs (more durable and stable)
    -Plastic construction with the horizontal ribs broken into different length segments, significantly reducing the “drumming” affect, among other things. This was the latest up to the PX panels. You will see the ribs at the top much closer together than the ones on the bottom with these.
    -PX panels. Total overhaul of membrane material, stator wire insulation and construction design and materials. A big deal imo. I believe they did get more efficiency out of these, even with an apples-apples dispersion version comparison.
    -PX Panels with Bass Focus. Basically the same as PX, but changed the horizontal rib spacings once again to improve bass response.

    #265
    bk12
    Participant

    In addition, regarding the backplate near consummate comments, there are many changes even between versions with the same Toroid version. Over the years, a few version notes:
    1) Backplates with attachment screws exposed (original, brown ones, very old)
    2) Backplates with screws hidden, a single low, jumper/banana tone control, vs. the later versions with 3 tone controls (quite old).
    3) Backplates where the bass transformer was wired to repel dust instead of attract it (forgive me for lack of more technical explanation on this one)
    4) Backplates with the 3 tone controls and new, improved mixer box and new values on the “crossover” components. I believe only the later versions of the 3 tone control backplates had the mixer and component value changes.

    I think there were other component changes above the few I mentioned above. Some of the backplates may have had these updates incorporated inside, it is hard to know without detailed photos of the underside. I wouldn’t be afraid to send them into SL to be completely updated.

    • This reply was modified 5 months, 3 weeks ago by bk12.
    • This reply was modified 5 months, 3 weeks ago by bk12.
    #268
    bk12
    Participant

    PS. One correction….the 2nd generation backplates had full jumper controls, including mid and low. It was just that vs. the selector knobs used in later versions.

    #269
    preale
    Participant

    All the previous suggestions make sense. I have done all of that (have hotrod backplates), but one thing not mentioned was to remove the brilliance control and replace it with a good Vishay resistor. You will have to experiment on the value (4-6 ohms), but dumping the brilliance pot is worth the trouble.

    #270
    hpfish10
    Participant

    My backplates have the bypassed brilliance control and Cardas wiring mods.

    #271
    John V
    Participant

    What are the Cardas wiring mods?

    #272
    hpfish10
    Participant

    Internal wirings and the jumpers use Cardas wire.

    #396
    Nolafile
    Participant

    Greeting,

    I’m in the process of bringing my Pristine II’s back to life. On these different panels. Are pics available for reference? I’m assuming I’m dealing with pre-PX panels. But it seems the transition may have been around the time they were produced.

    Thanks in advance,
    DD

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