Speaker‘s mid/upper bass boost is obvious. Solutions?

Yeah, would love to not use eq in the chain if possible for music playback. So far pure direct sounds best to me vs using eq in my preamp.

Thanks!

 

Not sure why it would show such strong dB for 20 to 40 Hz. I did observed amazing sub bass just from my speakers, without sub, when playing test bass tones a while back. 30 and 40 Hz can be surprisingly strong, more than the speaker's published capability. But 20 Hz? There must be something wrong with my measurement chain somewhere....Or I can't hear 20 Hz bass and the mic picked it up?

 

Yes, will try different positions, close port, etc. Thanks!

 

Yeah, it's the room. It may not be a peak as much as a null at your seating position. The best way to work with this, IMO, is to get a real-time readout of the frequency graph at the listening position. I have one speaker in a corner, which load the room more than the other, but I move the speaker until I get the best frequency response then work from that. I've found having the speakers closer to the back wall can help with some of this, although you lose on the imaging end. Good luck!

 

I did a measurements without any speakers output and found the same kind of frequency slope from 1k all the way to 20hz. There is no way my room is 90 dB at 20 Hz when nothing is playing.

Indeed, something is wrong with my capturing chain. It will be foolish to do more measurements until I fix this recording chain issue. I suspect the issue is my cheap external USB sound card. Without any mic input, using only the soundcard by itself, REW is seeing this kind of frequency. : (

Thanks for pointing this out!

 

I haven't used REW in a few years. You used to be able to create a calibration file of the sound card and load it into REW to correct for the sound card.

 

I've used REW, and it is good, but for what you are doing—roughing it out, you might do as well with something like this:

Free Spectrum Analyzer Plugin, FFT, Real-Time [VST, AU, AAX] - SPAN | Voxengo

Blue Cat's FreqAnalyst - Real Time Spectrum Analysis Plug-in (VST, Audio Unit, VST3, AAX) (Freeware)

I've also found that just measuring the quiet room you can see where AC duct noise, etc. can actually be pretty constant and boost noise in a certain frequency area. Good to know that stuff up front so you don't think it's the room or speakers.

 

Grea idea about creating calibration file!

I am now able to create a calibration file that produce a pretty flat line when using no speakers outputs.

However, I am not satisfied with my cheap USB card. Too much crosstalk between output and input signals. Significant signal leaks from 1K Hz and down.

Also, my AV preamp auto eq would increase the highs for both speakers and reduce 125 hz. With the calibration file added, I am now getting measurements with about -20 dB at 120 Hz as compared to frequency over 1k hz. I am not really trusting the results anymore.

Since I am using analog mic, I am going to get an USB mic preamp model as suggested by REW website.

Thanks again!

 

Thanks! First thing I need to do is to get properly working mic input chain. The cheap USB sound card is not working correctly. : (

 

Agreed, except (and this might be a matter of semantics) the "open door" acts more like a bass trap (due to the likely chance that it is not "tuned" to the interior dimensions of the room).

By the by, the rear of my main HT (link below) is open to the rest of the house, which acts like a big bass trap, and results in very smooth bass response throughout the room. Standing waves don't.

Jeff

 

All,

Thanks for the comments.

I think I know why certain songs sounded great and certain songs sounded not as good.

I was asking my speakers to play too loud for certain songs!

Vocals with simple instruments sounded fine. But playing back electronica with lots of bass freqs loud (average 80+ to 90+ dB at sitting position), with speakers ~12 ft away means I am asking my speakers to play at 95+ dB at 1 meter. My speakers can't handle such high volume at low frequencies without sounding stressed and outputting lots of distortions.

Here is a measurements of similar speakers (same bass driver) playing loud:


At 130 Hz and below, it has higher distortions playing loud. Bad at 50 Hz!

I got it to sound much cleaner by stuffing the front port and crossing it high at 120hz. I think my preamp has shallow drop at crossover point, thus I still get plenty of volume down low.

I then use a pair of subs crossed at 80 Hz and now I got clean sound playing back same electronica music loud!

I supposed using REW to measure my speakers at 75 dB would not have found such issue unless I measure at very high level, which I do not want to do with my speakers.