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Classix II Build...seems a bit inefficient??

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  • Classix II Build...seems a bit inefficient??

    DId a classix ii build from a kit i bought. Came with all drivers and components. Build the cabinets...did a black leather face on them with oiled walnut. I used walnut plywood from Hone Depot and walnut banding.

    Interestingly these seem to be more inefficient compared to other speakers i have. I have a multi way switch so i can a/b speakers (no gain control)...I compared these to 3 different Polk speakers (including the 4 ohm LSI9s), infinity, pinnacle and i was surprised that of the 5 different speakers i tested, these seemed to be the most inefficient ... meaning that i had to always turn up the amp when switching to these. I took the crosssover out and double checked the wiring on them both and they are proper based on the schematic on Pauls Site. Just wondering if that is normal or should i keep looking? I did measure the ohms at the input terminals and it was right around 8 ohms. Any thoughts?

  • #2
    If all other things were equal (which they most likely aren't), w/the same input voltage, a 4ohm speaker will play +3dB louder (it will also use twice the watts) as an 8ohm speaker. Also, many DIY designs here on PETT use full baffle step compensation, while many commercial designs do not. This can account for another seemingly 6dB of output "loss" (although it's really just a tradeoof between better balanced bass - and lower tweeter output level).

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    • #3
      No, the ClassixII's are trading size of enclosure and size of driver ( and price) for very low bass response and low distortion. Compared to a "4 ohm" LS19, they should take twice the power (about) as they are, as you measured, a very safe 8 ohm impeadence. It's not hard to build a speaker with this FR and double the efficiency, for 4 times the price...

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      • #4
        How do the Classix's sound compared to your other speakers?
        http://techtalk.parts-express.com/fo...khanspires-but
        http://techtalk.parts-express.com/fo...pico-neo-build
        http://techtalk.parts-express.com/fo...ensation-build

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        • #5
          Yes, these are extremely power hungry, but sound great and full doing so. Just had mine beating down the block tonight. Love em.
          Builds - C-Killa - Speedsters - LithMTM - Talking Sticks - Pocket Rockets - Khanspires - Dayton RS Center - RS225/28A - Kairos - Adelphos - SEOS TD12X - Dayton 8 - Needles - 871S - eD6c - Overnight Sensations - Tritrix (ported) - Lineup F4 - Stentorians - The Cheapies - Tub Thumpers - Barbells - Tuba HT - Numerous subwoofers - probably missing a few...... :p

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          • #6
            Hello

            I wouldn't worry too much about the efficiency unless you have small amp, where the desired volume level, whatever that is, makes the amp 'clip'. I have four pairs of speakers, and the Classix II are not the most, nor the least, efficient. My old Yamaha receiver is 80 Watts RMS and it hasn't been driven to clipping levels with any of our speakers.

            PE's published efficiency for the Classix II is 86dB, which compares well with other kits on its website. Of course, a well designed MTM or TMM will put out more sound but they cost more and have larger cabinets.

            I really like the Classix II sound, especially for the price. Like any speaker, you need to have the Classix in the right sized room and placed in a way which complements and optimises the sound. Efficiency is only one measure of a speaker's quality and attributes, and I've heard very "efficient" speakers which don't need much volume knob to sound awful.

            I hope you enjoy your Classix II, and the leather finish looks really cool.

            Geoff
            Last edited by Geoff Millar; 05-28-2017, 08:35 AM.

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            • #7
              Thanks all...makes sense. Just wanted to make sure i didnt do something wrong.

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              • #8
                Originally posted by Peterm View Post
                ...makes sense. ..
                See The Peak Power Demands of Well-recorded Music

                "Not a Speaker Designer - Not even on the Internet"
                “Pride is your greatest enemy, humility is your greatest friend.”
                "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

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                • #9
                  Most commercial speakers seem to focus on achieving high sensitivity in order to satisfy the marketing team. The drivers they use are designed for high sensitivity, and they trade a lot of bass extension to achieve that. If you look at all of the bookshelf speakers that are rated over 87dB of sensitivity, the bass almost always rolls off starting at 100Hz. The classix's bass rolls off a full octave below 100Hz, which normally means a 12dB sensitivity loss. But a combination of good driver specs in an optimal enclosure will reduce that loss to maybe 6-7dB.

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                  • #10
                    I own a pair of Lsi9's, and while I think they are rated for 88db 1W 1M, they do not have nearly the deep bass of the classix.

                    Even though they have 2 5.25" woofers, one is used exclusively for BSC, and only runs up to about 200hz

                    They tend to run out of steam bass wise,, somewhere in the 50's Hertz range.
                    I bet your classix, will go down to the upper 30s/

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                    • #11
                      I moved them up to our living room (they were in my office and too close to me so I could not really open them up). Now as I can really drive them they do really shine. The base is surprising....the sound so much better now that they have some "room to breath"

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