1st attempt charts : looking for advise

[venkatesh_m]

Hi All,

This is my first attempt in characterizing my room. My setup is as below:

Integrated Amp : Holfi Megarus 928 (upgraded)
CD : Holfi Xara (direct to int amp)
Mains : Dali Ikon6 (direct to int amp)
Sub : Dali IkonSub (hooked to integrated amp using sub out in amp L/R & LFE from Onkyo 875)
Surrounds : Dali Ikon OnWall
AV Amp : Onkyo 875 (fronts pre-out to aux-in to integrated amp)
BD Player : PS3 (waiting for the Oppo83)

I used a XP based laptop, SB Live Creative USB Sound Card, RadioShack SPL meter.

The 1st to the 4th charts uses output from the sound card to the Onkyo, the 5th chart is output from the sound card to the integrated amp.

The 1st chart (sub only) is input thru the cd channel in the AV amp and initiating the Stereo Mode on the AVR (Audyssey enabled). The front channels are fed thru the pre-outs on the AV amp to my integrated amp.

The 2nd chart (sub+main) is the same as 1st chart but includes the mains as well.

The 3rd chart is a full range measurement of the sub + main using the Onkyo's stereo mode Audyssey enabled (1/12 octave smoothing)

The 4th chart is a full range measurement of the sub+main using Onkyo's Pure Audio mode that has no Audyssey correction. These are sent out thru the front pre outs that are fed to the integrated amp. The integrated amp has sub outs as well. (1/12 octave smooting)

The 5th chart is a full range measurement (to 3kHz only) of the sub and mains but fed thru the CD input of the Megarus 928 integrated amp. (1/12 octave smoothing)

Please bear in mind that these are RS charts. I am waiting for the Galaxy CM-140 that I should receive in a week or two. However, the Audyssey corrected charts look much better with less peaks. I believe it might be better for me to switch the CD player to the AVR CD input and using Audysseys correction for CD listening as well. Does this make sense?

I would appreciate any inputs on this.

Thanks

[brucek]

RadioShack SPL meter.

The Radio Meters should only be used to 3KHz. You require a better meter for full range.

1/12 octave smoothing

Usually, 1/3rd octave smoothing is recommended for full range.
Turn off smoothing for sub graphs.

fronts pre-out to aux-in to integrated amp

You're passing the signal through two pre-amps?

brucek

[venkatesh_m]

brucek wrote:

The Radio Meters should only be used to 3KHz. You require a better meter for full range.


Usually, 1/3rd octave smoothing is recommended for full range.
Turn off smoothing for sub graphs.


You're passing the signal through two pre-amps?

brucek

Thanks brucek for your comments.

Ok. Have redone the full range measurements only to 3k. Will the Galaxy CM-140 allow me do the full range measurement? Also repost without the smoothing for the sub.

I currently have set up like this. My dedicated music CD player is hooked up to the CD input in my integrated amp. The Dali Ikon6 (mains) are hooked up to the integrated amp. My integrated amp has a L/R sub out. This is hooked to the subwoofers L/R inputs. This is how I normally listen to my music.

I also have a Onkyo 875 AVR. In order to utilize the mains as fronts, I utilize the front pre-outs in my AVR and hook them to the aux input on my integrated amp. I ran Audyssey this way and fixed the volume on my integrated at a fixed level. Also the LFE out in my AVR is hooked up to the LFE input on my sub. This way I get to use the sub for both music and movies.

I am contemplating hooking up my CD to the Onkyo CD input and using the stereo mode in the Onkyo to listen to music. Stereo mode in the Onkyo only sends signals to the front L/R and the sub. It sounded better to me. So I am using REW to confirm the differences.

The 1st chart shows the REW results for the sub only using the CD input (out from soundcard) from the Onkyo in stereo mode. This engages Audyssey correction.

The 2nd chart shows both the subs and mains using the CD input (out from soundcard) from the Onkyo in stereo mode. This engages Audyssey. My mains crossovers are set as 70Hz in the Onkyo.

The 3rd chart shows the same as the 2nd chart but full range to 3k. Much flatter response compared to without Audyssey (charts 4 &5 )

The 4th chart shows full range up till 3k for the sub and mains, but this time utilizing Pure Mode in the Onkyo. Pure Mode is supposed to be unprocessed by the AVR - no Audyssey. Seems so since it is identical to chart 5. There is a big peak ~ 37Hz.

The 5th chart shows full range but this time the soundcard output is sent to the integrated amp. The AVR is not in the loop at all. The chart shows the same peak at 37Hz. This does not have any correction at all. This is the mode that I would normally listen music with.

Hope all this makes sense.

Actually, I am pretty surprised with the sub response but I think it is Audyssey. I need to redo the sub only thru the integrated amp to see the effect.

[brucek]

Will the Galaxy CM-140 allow me do the full range measurement?

Yes..

I am contemplating hooking up my CD to the Onkyo CD input and using the stereo mode in the Onkyo to listen to music.

Passing the signal through two preamps would add the distortion and noise of the two systems. It's not really advisable. It might be acceptable for movies (not really considered critical listening), but not for music.

brucek

[venkatesh_m]

brucek wrote:

Yes..


Passing the signal through two preamps would add the distortion and noise of the two systems. It's not really advisable. It might be acceptable for movies (not really considered critical listening), but not for music.

brucek

Thanks brucek, never thought of it from a distortion and a noise point of view. I guess the next thing to do would be to tame the peaks in the sub. SVS seems to have a new equalizer that is meant for this. What would be acceptable in terms of the peaks? I believe flat would be best, but what level is acceptable?

I need to do some measurements of the sub alone and the mains alone thru the amp next.

Thanks for all the help.

[brucek]

Peaks in the sub signal are usually caused by room modes, and can be helped considerably by sub placement. Sometimes, fairly small moves can tame a peak. Try some placement changes before equalization, and then if you're not successful, get a BFD.

It would be nice if you could keep the peak below about 5dB. Your peak appears to be about 11dB.

brucek

[venkatesh_m]

brucek wrote:

Peaks in the sub signal are usually caused by room modes, and can be helped considerably by sub placement. Sometimes, fairly small moves can tame a peak. Try some placement changes before equalization, and then if you're not successful, get a BFD.

It would be nice if you could keep the peak below about 5dB. Your peak appears to be about 11dB.

brucek

Thanks brucek.

Got my Galaxy Audio CM-140 and carried out some measurements.

The first graph is of the sub and mains (thru the integrated amp), full range measurements. The curve starts to slowly decline after 1000Hz, is this normal.

The 2nd graph is the mains only. Much flatter response in the lower regions.

The 3rd graphs is the sub only. The 37Hz peak is apparent here. Need to move the sub around to see if I can defeat that. (Crossover knob at sub is set at 100Hz)

The last graph is using the AVR and Audyssey engaged. Graph looks pretty flat. Fronts are pre-out from the AVR to the integrated amp. This is just for reference since I never listen to music this way.

Appreciate your comments.

Thanks

[brucek]

Note: It's easier to look at graphs if you remove the soundcard and meter cal lines. The checkboxes at the bottom of the REW screen disable their display (not their function). Then set your target line for full range when you're measuring full range (you have it set to subwoofer). This gives you a good reference to compare your response against.
Try and set a 75dBSPL target level when measuring.

The Audyssey appears to remove the troublesome 37Hz peak fairly well. In fact, the response with Audyssey engaged is quite good.

brucek