Using a resistor to reduce bass output.

[ciphercomplete]

Hello, long time lurker 1st time poster here.

I know it is generally not a good idea to add a resistor inline with a woofer to say change impedance values and all that, but my question is more basic.

My situation is this. I have a biwire/amp pair of floorstanding speakers. A measurement of the room yields that frequencies below 500hz average about 5db to 6b louder than those frequencies above that cutoff. (I do have substantial room treatments). Would it be such a awful thing to wire a resistor in line to simply reduce the output of the bass section of my speakers? People seem to do this all the time to tame bright tweeters.

Thanks for any and all responses and your patience 😀

 

[Conrad Hoffman]

IMO, there's nothing wrong with it at all, assuming you prefer or can live with the sound of less damping. Listen carefully to the quality of the bass. Use sufficient wattage and choose the value as needed.

 

[davidsrsb]

If you are bi-amping a filter network on the input to the bass amplifier is a FAR better way to do this. Two resistors and a capacitor.

 

[cT equals piD]

There are two reasons not to wire the resistor in-series with the bass section:

Numero Uno: The average electrical power in the bass range (when playing music) is considerably greater than in the treble range. So the wattage rating of the resistor would have to be very high for floor-standing speakers and/ or might even require a heat sink.

Numero Two-o (Sorry my foreign language competence is in a high state of disrepair): Assuming that the resistance of the hypothetical resistor is comparable to DC resistance of the voice coil of the driver, then putting it in-series with the driver changes system Q and thus how the driver behaves at resonance.

In some cases resistance in-series with a woofer might be acceptable, in fact I put together a design like that. For one thing, if you have a low Qts woofer and must use it and system Q must be considerably higher for example in a closed-box system, putting a resistor in-series with the woofer allows increasing system Q without increasing the box resonance frequency that would occur by decreasing the volume of the box.

Regards, Pete

 

[Patrick Bateman]

If its a sealed box, you could add weight to the cone. (Output is lower with a heavier cone). Home Depot has removable rope caulk that's designed for weatherstripping that would do the trick.

 

[dumptruck]

There are some ways to try to pull off dropping bass with resistors, but nothing you've said indicates a good reason to bother with that mess. If you are using two amps, then of course you could just attenuate the input to the LF amp. If you're not, or if that doesn't give the response you want, you could use an active shelving filter before the amp(s), like the BSC filter on the Elliot Sound website. Let's hear what these speakers are, though. Also, is this a calibrated mic doing the measuring?

 

[dumptruck]

P.S. Really just state your whole measurement equipment/process. Lowering midbass levels could sound pretty bad if the speakers aren't to blame. Of course, if you have a way to play around with digital EQ, you could find out for yourself fast enough, if a bit crudely.

 

[Loren42]

Hello, long time lurker 1st time poster here.

I know it is generally not a good idea to add a resistor inline with a woofer to say change impedance values and all that, but my question is more basic.

My situation is this. I have a biwire/amp pair of floorstanding speakers. A measurement of the room yields that frequencies below 500hz average about 5db to 6b louder than those frequencies above that cutoff. (I do have substantial room treatments). Would it be such a awful thing to wire a resistor in line to simply reduce the output of the bass section of my speakers? People seem to do this all the time to tame bright tweeters.

Thanks for any and all responses and your patience 😀

The difference between tweeters and woofers is that 50% of the audio power resides below 500 Hz. That means a big wattage resister is required to turn the excess sound into heat.

Heat is not a good thing for crossovers inside a cabinet.

A better solution is to relocate the speakers somewhat or maybe consider bi-amping.

Bi-wiring is a useless endeavor and would do nothing to solve your issue. Bi-amping would allow you to easily contour the sound to your liking.

Lastly, a good EQ might be a simpler solution as long as the problem is not actually the room and causing excessive node and anti-nodes. EQ can not fix that. You need to fix the room.

 

[ciphercomplete]

Wow, thanks for all the responses and info. To answer a couple of questions. My speakers are Tyler Acoustics Decade D2. I have a smallish room about 15 foot by 16.5 foot and I know these speakers are probably too big but I really like them alot. I wanted to try everything before opting for a smaller set. I have been using REW to measure my room while I have been building bass traps.

Whoever brought up the heat issue (I think it was more than one person) thanks and I am really glad I posted here before experimenting. That side of the equation completely slipped my mind.

Loren42, your suggestion to bi-amp struck a chord with me because I bi-amp my last pair of speakers but I never tried adjusting the sound by attenuating one of the amps. But I just so happened to have a pair of Rothwell 6db attenuators laying around so I grabbed one of my hometheater amps and hooked things up. Long story short I tried it out and wow, I believe I have found my solution. I just need to fine tune everything by figuring out just how much I want to attenuate and buy a second amp.

Thanks again everybody.