Power amp upgrade
- Thread starter Randy Gartner
- Start date
Are you running a single channel of each 3402 to a sub? If so, you have about 1100 watts per sub. The 151 drivers are rated at 300 watts continuous, which would be 600 watts for the pair. At 1100 watts, you are at just about double the RMS for the pair. What you have for amplifiers are a safe configuration for normal music playback. For more dynamic music, such as a live band, you could get away with a larger amp. Often times, the 'peak' rating of a speaker is 4X RMS. This is what the speaker can take for a very short duration, such as the hit of a kick drum. So, if you put a 2400 watt amp on each sub, you could gain a bit more on the kick. The catch is, if you now play heavily compressed music, you run the risk of blowing up your speakers long before you see any clip indicators come up on your speakers.
Personally, I like to use smaller amps and more speakers. I don't mind buying speakers. I HATE paying for speaker repairs!
Personally, I like to use smaller amps and more speakers. I don't mind buying speakers. I HATE paying for speaker repairs!
What are the cabinets your using, size, tuning, ports ect. I guess I'm getting at that maybe a speaker upgrade / update could give you more of what your looking for. The K151 was a humping 18 inch speaker back in the mid 70's but there are lots of higher power and higher output 18's available today. The K151 has a rating of 99db one watt one meter but that was measured at 500hz through 2000hz most likely not the frequencies there being used at.
The cabinets are made by Mueller Speaker. John worked for Clair for many years and uses a computer program to plug in the info from the manufacturer to build the cabinet to those specs. I am very happy with the sound and performance of the cabinets. I believe the subs are tuned at 40hz. I have 4 double 18 subs, 2 double 15's for lows, 4 single 10's with 1" horns. Everything is JBL except the 10's. Using a Midas Pro1, Ashley 4 x8 processor with 3402 on the subs, 3002 on the lows, 2402 on the mids and a Lab Gruppen FP 2400 on the horns. I'm just looking for a little more headroom so my thought was buy 2 bigger amps for the subs and move the other amps up the chain.
Randy,
When it comes to sub-woofers (or internal combustion engines) there is no replacement for displacement.
Displacement in loudspeakers is measured by the one way linear stroke, Xmax, generally in mm (milimeters). The linear stroke peak to peak is twice Xmax.
A woofer with twice the displacement, given 6 dB more power, will put out 6 dB more output.
Your K151 Xmax is only 2.54mm, similar to some 3" speakers, modern PA 18" woofers such as the B&C18SW115 have more than 6 times that displacement, 18dB more output. Some competition car drivers have as much as 30mm Xmax!
A 10 dB increase in SPL sounds "twice as loud" to average ears at 1000 Hz, it takes less at lower frequencies, around 5 dB at 20 Hz sounds "twice as loud", though with a 40Hz Fb, your boxes won't do much below 35 Hz.
You could purchase new drivers and get four times the sound in the roughly the same cabinet volume (though port size would probably need to be larger, reducing cabinet volume and sensitivity a bit), or "upgrade" your sub amps and hear the sound of your K151 distort like pigs- Xmax is also the displacement at which THD is 10%, once driven beyond Xmax (probably only a few hundred watts with your very sensitive K151s) the speaker rapidly will exceed 100% distortion.
Cheers,
Art
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And let's not forget that with subwoofers, harmonic distortion is rather more audible than in higher passbands, due to the ear being more sensitive to the harmonics than the fundamental frequency
Rob,
Although I get your general drift, lets not forget the third harmonic (odd order) of 1333 Hz is 4kHz, where normal ears are the most sensitive to SPL in general, and distortion is most objectionable. Sub-woofer distortion is usually predominantly even order, unless the drivers are oriented in a push-pull arrangement. Even order distortion is musically benign, it does not add any notes not present in the original composition.
Some of us are more sensitive to LF distortion, but most detect HF distortion, which often has more odd-order harmonics, more readily.
Art