Comparing readings with and without sub - Paradigm 700F

[wavetrade]

I am usually a bookshelf speaker junkie but recently bought these speakers as the room they are in is largish and I wanted to give towers a try. On my first set of REW measurements I have ended up curious why running with the sub seems to have an impact on the frequencies over 1K. Specifically the rise that occurs at about 12K when the sub is running. In addition to this I notice that there is kind of trough from 2k to 8k with the subwoofer. But without the sub I get kind of a hump in this region.

I am thinking it might be incidental and due to microphone placement during testing. These are averages of 3 readings each session, with mic centered and then slightly to the left and right. The sub is a REL T5X connected high level. I had the mic pointed forward on this run and am going to do more readings tonight with the mic at 90 degrees.

But in the meantime thought I would ask... Can a subwoofer impact the higher frequencies?

 

[Chrispy]

Calling a Rel T5X a sub is a stretch to begin with....but depends how you're integrating it and sure it can affect higher frequencies depending....

 

[wavetrade]

Calling a Rel T5X a sub is a stretch to begin with....but depends how you're integrating it and sure it can affect higher frequencies depending....

I started a little put off by the Rel comment. But then looking at the graph it kind of proves your point, it isn't doing much more than the main speakers. That said, it was great in a smaller room with LS50 Meta speakers. I will get something bigger and better for the current room.

 

[Chrispy]

I started a little put off by the Rel comment. But then looking at the graph it kind of proves your point, it isn't doing much more than the main speakers. That said, it was great in a smaller room with LS50 Meta speakers. I will get something bigger and better for the current room.

Might have a slight advantage over the LS50s but that's not saying much.

 

[Beave]

The subwoofer should have no impact on those frequency ranges, or anywhere near them. Most likely it's an issue with mic placement consistency. Or different EQ settings.

 

[Chrispy]

The subwoofer should have no impact on those frequency ranges, or anywhere near them. Most likely it's an issue with mic placement consistency. Or different EQ settings.

Up to what frequency would that be?

 

[Beave]

Sorry, it wasn't clear that I was responding to the OP's questions about the differences between his two plots (one with sub, one without), in the range above 1kHz.

 

[kyuu]

I started a little put off by the Rel comment. But then looking at the graph it kind of proves your point, it isn't doing much more than the main speakers.

Just looking at the frequency response can be misleading, as even something like the Rel T5X is going to have a lot more to give at those low frequencies than the LS50s.

But given the appearance of what is likely a room mode at just under 60Hz in addition to the other frequency response changes, it seems likely that microphone positioning or some other difference between the measurements is likely to blame.

 

[DVDdoug]

I'd agree it's probably microphone placement or other normal measurement variation... This has a bigger effect at higher frequencies (shorter wavelengths).

The difference in the low-frequency room modes (dips and bumps) is likely from the sub being in a different location than the main speakers.

...I was doing some experiments once with high frequency test tones (maybe 5kHz) and an SPL meter on a mic stand. I was standing behind the mic stand and when I moved around the readings changed by several dB! My body was affecting the reflected soundwaves.

The loudness in my ears also changed drastically when i moved around or simply moved or turned my head. That didn't surprise me... We don't usually notice this with music (or other program material) but it's very noticeable with test tones. At 5kHz the wavelength is 2.7 inches. If you are 1/2 wavelength off-center, the left & right soundwaves are 180 degrees out-of-phase and they will cancel. Of course, both ears can't be in the exact center. Plus, there are multiple reflected waves that combine with random delay and phase depending on where your ears (or microphone) are located.

 

[wavetrade]

It was microphone placement. And perhaps some other minor issues. I changed to a 90 degree setup on the mic and carefully took 5 measurements each, with and without sub. Then RMS averaged them. Results were more inline with expectations. Also provided me my favorite sounding EQ file.

Thanks for the help.

 

[jonfitch]

High frequencies are directional and there's no way the T5/X's downfiring driver is generating that signal. That said, I recall when testing Rel subs that the amps were pretty noisy with what sounded like toroidal hum in the 100 range, but that probably was too low in level to be picked up from a mic several meters away. Looking at your graph it looks like you would benefit from EQing the sub as it appears to have a peak around 60hz.

 

[wavetrade]

High frequencies are directional and there's no way the T5/X's downfiring driver is generating that signal. That said, I recall when testing Rel subs that the amps were pretty noisy with what sounded like toroidal hum in the 100 range, but that probably was too low in level to be picked up from a mic several meters away. Looking at your graph it looks like you would benefit from EQing the sub as it appears to have a peak around 60hz.

Interesting thoughts here. Once I took measurements a second time, being much more careful, I am not seeing any difference above 200HZ with or without sub. So that sorted out my initial question.

Some of the comments on this thread got me questioning using the T5/x as my sub and I ended up replacing it with a SVS SB-3000. The response with it is flat all the way down to 16HZ in my room, it is quite a change! Thankfully I did not have any trouble integrating it into my system and music still sounds great. And I can feel movie scenes now, lol. Once dialed in I do some light EQ'ing to reduce the peaks. I use my RME dac to accomplish this and am limited to 5 bands, but it does the trick.