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<blockquote data-quote="Art Welter" data-source="post: 34970" data-attributes="member: 52">Re: SH-50 limiters.The IEC standard (IEC60268-3) allows any impedance above the rated value, but limits the impedance below. It does not allow the rated impedance to fall below the 80 % of the nominal value at any frequency..I don’t know if the SH-50 has been redesigned, the old “6 Ohm” spec sheet claimed a minimum impedance of 3.5 ohms at 16 K, obviously well below the IEC60268-3 standard.According to the new spec sheet,&nbsp; though the SH-50 averages around 6 ohms, it dips below 4 ohms at 90 Hz, but the 16K impedance looks to be around 5 ohms now.Setting an RMS or peak limiter to a specific voltage only limits the power relative to the specific impedance at a particular frequency, obviously the amp will produce a lot more power into the SH-50 at 90 Hz than 500-600 HZ, and the woofers will take far more power than the tweeter (HF driver).Put 66 to 77 volts of sine wave at 16K into the SH-50 and you won’t have a tweeter after a few seconds, but that much average voltage in with “normal” music won’t be a problem.Just watch out for Hi-Hat solos, your limiter won’t protect the tweeter from them ;^).As far as your questions, your numbers are not off, I’d call the SH-50 a 4 ohm box, although nominal impedance and dispersion is just a name- the SH-50 is also a 50 x50 degree nominal dispersion box in the upper range, but not in the woofer range.As far as a recommended limiter setting, that would depend on who (and what) you are trying to protect the box from.</blockquote>

[QUOTE="Art Welter, post: 34970, member: 52"] Re: SH-50 limiters. The IEC standard (IEC60268-3) allows any impedance above the rated value, but limits the impedance below. It does not allow the rated impedance to fall below the 80 % of the nominal value at any frequency. . I don’t know if the SH-50 has been redesigned, the old “6 Ohm” spec sheet claimed a minimum impedance of 3.5 ohms at 16 K, obviously well below the IEC60268-3 standard. According to the new spec sheet, though the SH-50 averages around 6 ohms, it dips below 4 ohms at 90 Hz, but the 16K impedance looks to be around 5 ohms now. Setting an RMS or peak limiter to a specific voltage only limits the power relative to the specific impedance at a particular frequency, obviously the amp will produce a lot more power into the SH-50 at 90 Hz than 500-600 HZ, and the woofers will take far more power than the tweeter (HF driver). Put 66 to 77 volts of sine wave at 16K into the SH-50 and you won’t have a tweeter after a few seconds, but that much average voltage in with “normal” music won’t be a problem. Just watch out for Hi-Hat solos, your limiter won’t protect the tweeter from them ;^). As far as your questions, your numbers are not off, I’d call the SH-50 a 4 ohm box, although nominal impedance and dispersion is just a name- the SH-50 is also a 50 x50 degree nominal dispersion box in the upper range, but not in the woofer range. As far as a recommended limiter setting, that would depend on who (and what) you are trying to protect the box from. [/QUOTE]

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