Sierra Tower w/RAAL in room response question

[djDANNY]

As Dave says, he needs the phase control on the sub. Phase integration is important, at least as important as EQing.

With two people, it is pretty easy. Say your crossover is set for 80hz. Have one person with an SPL meter sitting at the listening position, have the other person adjusting phase. Play an 80hz tone, and while adjusting the phase, watch the SPL meter. As you are adjusting the phase, you will see the output on the meter vary...at its highest output point, that is when the phase is correct at 80hz. Play the tone through the system, not just the sub, so that the crossover and mains are in effect.

Any device that just works on the sub, is not going to correct phase with the mains.

Phase alignment with the mains should really be your last step after EQing the subs and setting proper gains/levels first.

[jimlucci]

Today I ran sweeps of just the Towers individually, together and then with the Subwoofer. I tried different positions within my room and finer adjustments within those positions. With the mains, I found that no matter what positions within the room I used, there was at least one and often 2 or 3 pretty big peaks and nulls (focusing mostly under 500Hz). What I learned with that exercise was that there was no clearly superior position for my Towers within my space. With that, I set the mains as per my original room diagram - this position had the least amount and severity of peaks and nulls.

I then ran sweeps with just my L12 (crossover 80, slope 24, peq off) in different room positions. Unlike with the Towers, there were really only 2 positions in the room that stood out (plus I did not have to worry about directional issues with the sub placement). One position covered the sharp null in the Towers at around 80Hz, but was generally worse other than that. The other position was much better under 60Hz but had the same sharp null at around 80Hz that the Towers had. I chose this second position and ran the sweeps with the Towers while adjusting for delay/phase. It was clear in the response curves when the sub was adjusted differently from 0 to 180deg where it aligned best with the towers. After the phase was set, I used the peq option on the L12 to soften a peak at around 30Hz.

Conclusions:

I do believe that if I added another L12 in the other sub location I could certainly smooth and enhance my lower frequency range.

Unless I can do some sort of room treatments and/or equalization this is the best I can do within my space. I think the adjacent room behind my mlp is causing most of the irregularities in my freq response.

Measurements aside, I find that these Sierra Towers and the Rythmik L12 sound incredible. They play plenty loud without a hint of strain. The bass is tight and authoritative, the mids and highs are clear and detailed. The RAAL tweeters are just amazing - in all the time I have spent listening, I have never felt that fatiguing sensation.

Advice, insights are always welcomed.

southfinalspl.jpg

southfinalwater.jpg

[davef]

Phase alignment with the mains should really be your last step after EQing the subs and setting proper gains/levels first.

Actually, just the opposite. Phase issues between the sub and speakers will cause peaks and nulls in the response that cannot be corrected by EQ (it will only make them worse). Once phase on the sub is properly set, EQ'ing becomes much simpler as you are then simply adjusting for room acoustics.

[davef]

Today I ran sweeps of just the Towers individually, together and then with the Subwoofer. I tried different positions within my room and finer adjustments within those positions. With the mains, I found that no matter what positions within the room I used, there was at least one and often 2 or 3 pretty big peaks and nulls (focusing mostly under 500Hz). What I learned with that exercise was that there was no clearly superior position for my Towers within my space. With that, I set the mains as per my original room diagram - this position had the least amount and severity of peaks and nulls.

I then ran sweeps with just my L12 (crossover 80, slope 24, peq off) in different room positions. Unlike with the Towers, there were really only 2 positions in the room that stood out (plus I did not have to worry about directional issues with the sub placement). One position covered the sharp null in the Towers at around 80Hz, but was generally worse other than that. The other position was much better under 60Hz but had the same sharp null at around 80Hz that the Towers had. I chose this second position and ran the sweeps with the Towers while adjusting for delay/phase. It was clear in the response curves when the sub was adjusted differently from 0 to 180deg where it aligned best with the towers. After the phase was set, I used the peq option on the L12 to soften a peak at around 30Hz.

Conclusions:

I do believe that if I added another L12 in the other sub location I could certainly smooth and enhance my lower frequency range.

Unless I can do some sort of room treatments and/or equalization this is the best I can do within my space. I think the adjacent room behind my mlp is causing most of the irregularities in my freq response.

Measurements aside, I find that these Sierra Towers and the Rythmik L12 sound incredible. They play plenty loud without a hint of strain. The bass is tight and authoritative, the mids and highs are clear and detailed. The RAAL tweeters are just amazing - in all the time I have spent listening, I have never felt that fatiguing sensation.

Advice, insights are always welcomed.

southfinalspl.jpg

southfinalwater.jpg

That 10dB null at 80Hz, then 10dB boost 1/2 octave lower is a phase issue. Have you played with the phase control on your sub as Curtis advised?

[davef]

With two people, it is pretty easy. Say your crossover is set for 80hz. Have one person with an SPL meter sitting at the listening position, have the other person adjusting phase. Play an 80hz tone, and while adjusting the phase, watch the SPL meter. As you are adjusting the phase, you will see the output on the meter vary...at its highest output point, that is when the phase is correct at 80hz. Play the tone through the system, not just the sub, so that the crossover and mains are in effect.

Excellent post and a very simple method to use.

[jimlucci]

That 10dB null at 80Hz, then 10dB boost 1/2 octave lower is a phase issue. Have you played with the phase control on your sub as Curtis advised?

Yeah, I tried 0 to 12ms (0 to 180deg) and everything in between. I get same dip when I run the Towers alone (no subwoofer at all). I seem to get a sharp dip around 80 and 200 when running just the Towers no matter where I set them in the room (it is always there maybe shifted slightly). Is it possible the Towers are out of phase? or a problem with one of the woofers?

I also had a bad thought about a why there could be a problem. I did run them at some point with the grilles oriented incorrectly (see post started by racrawford65). The upper woofer in each Tower are the drivers that were affected, but they appear to be operating correctly. I know a test that would prove/disprove that, but before I do anything, I want to make sure I am not chasing a ghost here. I know in room responses can vary significantly, so I don't really know what to expect. Could'nt room modes/boundary issues cause those?

Here is a close up of the Towers from 10-500Hz in room without subwoofer:

[jimlucci]

Excellent post and a very simple method to use.

I tried this idea and it confirmed my phase setting. I ran a low frequency (30-80Hz) continuous tone while adjusting my phase dial. 0 deg (0 ms) was about 82 spl. 180deg (12ms) was about 88 spl.

Good idea there. Thanks Curtis!!

[curtis]

I tried this idea and it confirmed my phase setting. I ran a low frequency (30-80Hz) continuous tone while adjusting my phase dial. 0 deg (0 ms) was about 82 spl. 180deg (12ms) was about 88 spl.

You should just run an 80hz tone, if that is where your crossover is set. You don't want anomalies from other frequencies with their room interactions to affect the SPL. 80 hz is where you want the phase to be correct.

[curtis]

Jim...do you run the speakers large or small? Are you sending the frequencies below 80hz to the speakers as well as the sub?

[curtis]

and can you run a 10hz to 500hz sweep with just the sub?