The misunderstood Bertagni speakers.

Discussion in 'Equipment Reviews & Opinions' started by hoggwild89, Jan 29, 2011.

  1. hoggwild89

    hoggwild89 Active Member

    Messages:
    147
    Sub titled: My new score.

    I have seen some bad reviews on this line of speakers but I am here to tell you that my opinion is quite the opposite. The people that tried them just didnt understand the nature of the beast.


    A really nice guy brought me three sets of three different model Bertagni "planar" type speakers. Two pairs had issues and a pair of SM-255 MKII's for "spare parts".

    For those of you that have never heard of BES, Bertagni: They were made mid to late 70's. The driver is a block of Styrofoam (?) about 2 inches thick, that is shaped and tuned into two or three or four (depending on model) resonant sections. The voice coils are epoxied directly to the styro and the magnets are mounted on an aluminum frame. The tweeters are Piezo mounted onto a cone that is epoxied into a stryo chamber.


    What I found:
    The voice coils can break free from the epoxy (found on the web), I did not see this in all three pairs.
    All the screws on the speakers and frames get loose. Repositioning the speaker magnets requires driving the speaker and sweeping it with a signal generator to make sure the magnet "pole piece" is in the center of the coil without rubbing.
    One one of them the magnet came loose from the mounting plate. You can not reposition the plate on the magnet, impossible outside of a speaker manufacturing plant. (degaussing apparatus needed) Discard the mounting plate and epoxy the speaker directly to the aluminum frame.
    Using the same generator sweep method find the areas that resonate and "buzzzzzz". like in my case the coil/cap combo on the midrange vibrated on the aluminium frame are some frequencies. pry/shove/move and apply silicone.
    Piezo's. Wow, holy crap! Excise them from their paper cone and remove all traces of epoxy. clean with MEK. SOLDER a jumper from front to back, they used a spring clip, it gets oxidized. re-solder wire leads. re-epoxy back onto the cone.

    Add an 80hz high pass cross over to the speaker input jacks to keep all lows 80 hz and down off the entire speaker, then use these with a separate woofer/sub woofer. NOW these things sound AWESOME for Smooth Jazz and classical.

    FURTHER NOTES:
    My buddy GAVE me the "parts" SM-255's. I spent about 8 hours on them doing all of the above. (acutally I spent about 6 hours on EACH speaker he brought, tweaking until I was satisfied, then moved onto these) I use a Niles speaker switch/volume control and use a set of Klipsch Cornwall's for the mids/low/sub low and the BES's for lows @80hz and up/ mids and highs. Amps are Dynaco MKIII's

    The overall sound will bring tears to your eyes with joy. Its better than Viagra.

    If you can find a pair of these on CL, scoop them up and start tweaking, you will NOT regret it.
     

     

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  2. Duckzilla

    Duckzilla "Laugh it up fuzzball"

    Messages:
    1,431
    Location:
    Vassar, MI
    I had a pair of SM250 II, and concur, very detailed speakers, just lacked oomph.
     

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  3. PLammers

    PLammers New Member

    Messages:
    15
    I've got the sm100s connected to a bose am5 woofer and they sound quite good. I'm going to run them in awhile before I play them loud.
     

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