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View Full Version : The smell of hot pc board



sirogenous
07-31-2001, 04:03 AM
Hello Kim or other,

When pushing my 3065's (at least I think so) towards their uppermost limit, I can sometimes detect the faint smell of hot pc board. I believe it is not coming from my amp (sony HX1002) since no matter how loud I go, it never gets any warmer then a 115 to 120 degrees F. Heck my video card has hit 160!. As soon as I detect this smell I immediately lower the volume level. The only time I crank the volume is when driving down the freeway to be respectful of others, so locating the exact source is rather difficult to do. However, I suspect that the smell may be coming from the resistors getting hot in the crossovers that polk supplies with the DX's. Would pushing the crossovers as such cause the resistors to run hot. Common since tells me it should. Also, I use the amp in high pass mode, with the cut off freq. near 60 or 70 hz. so not to over stress the the mid/woofers. Is this wise to do. Or would it be better to lower the 62 hz position on my EQ. I understand that using crossovers with a 12 dB slope can cause an increase in the amount of current which will bypass the speaker at or near the crossover freq. The have the crossovers set to the 6 dB roll off possition. One more thing, with the crossover setting at or near 70 hz. also slightly increase the power handling capabilities of the speakers.

Kim
08-01-2001, 09:54 AM
What you are probably smelling is the power resistors in the
crossover network. If you can smell them, then you are driving
them TOO HARD!!!. Try setting the high pass cossover to a higher
crossover point. Somewhere between 90 to 120 Hertz. This will reduce the high current demand that is placed on the amp to drive the speakers at that high of a volume level. Does the amp use a 12 dB or 18 dB per octave active crossover??

If you are still having any problems, feel free to give us a call at
800-377-7655 between the hours of 9 AM to 6 PM Eastern time and we will be glad to help.

Thanks,
Kim, Polk Audio

sirogenous
08-02-2001, 03:22 AM
Hello Kim,

After doing some series of listening test, I have decided to no longer use the amplifier in Hi Pass mode. The system just sounds so much better to me without using this setting. I have always preferred musical accuracy over thumping bass so keep the the bass freq's. fairly unboosted. 62Hz. @0dB gain, 157Hz @+2dB and 396Hz @+1dB. Since reverting back to using the amps Hi/Low pass option in the "OFF" position, I have not detected the smell of "hot electronics. Hmmm.... Maybe the overcurrent effect was ineffect even though the crossovers are at the 6dB roll off setting and not at 12dB. Instead of using the high pass setting, I'll stick to simply lowering the gain. I have noticed that there are different max. power ratings listed for the DX3065's. Polks on-line specs. list it to be 140 watts. While the installation manua lists it at 130 watts. Since I misread the power specs for the Sony amp, which I had thought it was rated for a max of 170 watts, only to find it's rated at 230 max per channel, I know I need to be careful while listening to loud music. I know this is somewhat off topic though , might you be able to tell me what the dynamic range is of an amp that is rated at 100 watts 20Hz-20kHz @4ohms or 140 watts @2ohms. and 230 watts maximum per ch. If memory serves me correctly it should be nearly 4 dB. correct?