1st Runs on my HT System

Here's the first runs with REW on my HT's main speakers (l/r) and subwoofer.

Any comments would be appreciated.

The first graph is my left main
second graph is my right main
last is the sub.

One thing I found is that even though my SPL was calibrated properly to 75db when set to the 80 range the REW always said the level input was too low.

But if I set it to the 70 range the graph would be centered around 85 rather than 75. Is the latter the correct way to do that?

[brucek]

I t would appear you don't have any crossover engaged on your mains. When the sub and mains combine you may have a bit too much bass.

Have you taken a reading with sub + mains?

If you have set your levels with the subwoofer test signal, be sure the End Freq setting in the measurement tab is at 200Hz, so the overall measurement level won't be too low. Also don't forget to use the set target level routine.

brucek

[atledreier]

Looks like the fronts and sub should complement each other pretty good if you integrate properly. Might be a bit on the bass-heavy side though.

Edit: Just noticed the scale is different on the graphs. Please use the 'Shack standard' scale on graphs, that makes them easier to compare.

I actually do have a crossover engaged at 60Hz. The only thing I can think of is that the receiver was set to "Pure Audio" mode, which bypasses all internal processing on the receiver. This mode may prevent the crossovers from being engaged, but it is how I listen to music. For movies I use DD or DTS, so maybe I should use the "Direct" mode rather than "Pure Audio".

I haven't done a reading with both the mains and the sub. Where do I select that measurement type? Or how do I do that measurement? Would it just be a matter of connecting both the Left and Right speakers to the sound card? How would I also generate the sub as well?

My soundcard is an MAudio Audiophile 2496, which has L/R RCA inputs and L/R RCA outputs, as well as a MIDI adapter for SPDIF COAX input and output.

It's really my first attempt so sorry about all the questions.

I followed the online help manual instructions, and my steps are summarized here:
1. Calibrated sound card by connecting L/R input to L/R output and taking measurements from the soundcard panel, then saving .cal file.
2. Connected soundcard Right output only to Right speaker input on multichannel mode of the receiver, and set receiver to multichannel mode.
3. Connected Right input on soundcard to RS SPL meter's output and positioned the meter on a tripod at the main listening location.
4. Set RS SPL meter to 80db setting.
5. Using a speaker calibration signal, calibrated SPL to 75db by raising receiver's volume level until SPL showed 75db.
6. Performed measurement by first checking levels (which showed as -29db and too low). If I moved the SPL meter setting to 70db, then the levels were fine. This is the problem I described before. I left it at 80db for the above measurements. Also, I set the End Freq to 200Hz.
7. After measurement, Set Target in order to find the corrected dB.
8. Repeated steps for the other speaker after moving RCA cable to other speaker's input on receiver's multichannel area, still using Speaker Calibration signal.
9. Changed signal to subwoofer calibration signal and moved RCA cable to receiver's sub input on the multichannel area, and performed measurement for subwoofer.

My equipment:
MAudio Audiophile 2496 sound card
Onkyo TX-SR705 AVR
Paradigm Monitor 7s (mains)
SVS PB-10 (sub)
Paradigm CC-370 (centre)
Paradigm ADP-370s (surrounds)

My room:
Large open concept basement (900 sq ft)
But main HT area is 14'x15' (but opened beyond that area to 18'x30')
7.5' ceilings, and in some areas 6.5' (under ductwork, etc.)

brucek wrote:

I t would appear you don't have any crossover engaged on your mains. When the sub and mains combine you may have a bit too much bass.

Have you taken a reading with sub + mains?

If you have set your levels with the subwoofer test signal, be sure the End Freq setting in the measurement tab is at 200Hz, so the overall measurement level won't be too low. Also don't forget to use the set target level routine.

brucek

Could you explain how you can tell that I don't have the crossovers engaged on the mains? Just trying to learn how to decipher the measurements.

[brucek]

Could you explain how you can tell that I don't have the crossovers engaged on the mains? Just trying to learn how to decipher the measurements.

I simply looked at the response and could tell it doesn't comply with a standard 80Hz crossover.

Below are two REW target diagrams showing what a subwoofer and mains should look like (in a perfect world) when a crossover of 80Hz is set in a receiver. The two outputs will combine for a perfect flat response.

MAINS should look like this (yours does not).


SUBWOOFER should look like this.

Connected soundcard Right output only to Right speaker input on multichannel mode of the receiver

This is a poor way of doing this.

Hook up the output of the soundcard to the AUX or CD input of your receiver with a splitter Y cable.

Put the receiver in stereo mode. Now only the sub and mains will play. Be sure the mains are set to small and the crossover you like is setup (i.e. 80Hz).

Disconnect the Mains speakers (with the power off of course).

Now the sub only signal will output when REW is running and the crossover will be engaged. The sub will look like the diagram above for the sub....

Now shutoff the subwoofer and connect up the mains and run REW and the crossover will be engaged for the mains. The mains will look like the diagram above for the mains.

When you turn the sub back on you can take a measure of the mains + sub to see the crossover integration.

Use the Check/Set levels with Subwoofer test signal setup in the Settings screen to do all the tests..

brucek

Thanks for the feedback.

My MAudio card has a L/R input as two separate RCA jacks, and a L/R output as two separate RCA jacks.
I have been connecting using only the Right rca input jack to the SPL meter's output (sound card's Right input) and then the Right rca output jack to the receiver.

Are you saying I should use a Y cord to take connect to the SPL meter's output and run the other end to both the L/R RCA input jacks on the sound card?
And then run the L/R RCA output jacks on the sound card to the L/R CD input on the receiver?
And then do the disconnecting as per measurements as you mention?

And lastly, should I use the subwoofer signal for the speaker calibrations as well?

[brucek]

I have been connecting using only the Right rca input jack to the SPL meter's output (sound card's Right input) and then the Right rca output jack to the receiver.

Correct...

Are you saying I should use a Y cord to take connect to the SPL meter's output and run the other end to both the L/R RCA input jacks on the sound card?

No, leave the SPL meter as it is, I'm saying to take the simple mono output from the soundcard (as you are doing now) and feed it to the AUX input of your receiver (using a Y-splitter). This is the normal way everyone hooks up REW. It allows left and right speaker to be engaged.

And lastly, should I use the subwoofer signal for the speaker calibrations as well?

Yes, because we're interested in their response from 15hz-200hz.

brucek

Understood.

The only thing is the simple mono output from my soundcard is actually not simple mono...it's L/R channel (dual RCA jacks).

So would I take a cable only from the Right output of the sound card to the Y cord and then to the L & R on the receiver's AUX?

Or from both the L & R outputs on the soundcard to the L & R on the receiver?

[brucek]

it's L/R channel (dual RCA jacks).

Yeah, a little known fact is that REW actually outputs the same mono signal from both its Left and Right output of the soundcard, so you can simply use L & R from the soundcard to L & R of the receiver AUX input. Put the receiver in stereo and leave all the soundfields shut off and the mono signal will pass the the left and right mains speaker and sub.......

brucek

Ok, I redid the measurements as per your advice. Here are my results in the following order:

Sub
Left main
Right main
Both mains
All mains + sub

Any comments welcome

[brucek]

Good job...... (although I don't really like saying that to a Leafs fan)....

You have a fair resonant peak at ~22Hz. If you turned up the sub a bit and had a BFD, you could lower that peak and have quite a smooth response. As it is, I'm sure a lot of your bass is that single note. Have you tried moving the sub around a bit to clear the peak?

brucek

Here's what I just came up with as what I think is my best sub measurement. Had to move it behind the couch and adjust some of the sub equalizer in my receiver.

Is this a good setup for the sub?

brucek wrote:

Good job...... (although I don't really like saying that to a Leafs fan)....

You have a fair resonant peak at ~22Hz. If you turned up the sub a bit and had a BFD, you could lower that peak and have quite a smooth response. As it is, I'm sure a lot of your bass is that single note. Have you tried moving the sub around a bit to clear the peak?

brucek

Thanks. How about my latest sub graph. I think I reduced the 22Hz peak by 7db.

I now have 5 peaks on the sub, and all are under 7.8dB. Is that good?

What is the guideline for keeping the peaks under? Is it 10dB?

[brucek]

What is the guideline for keeping the peaks under?

I don't know if there really is a good guideline. I guess it would be great if there were no dips or peaks greater than 5dB, and you can generally discount sharp dips because you'll never hear them.

I think your sub looks pretty good, but if I had that plot with a BFD attached I would probably EQ down at 22Hz, 30Hz and 55Hz a bit. You can certainly add some filters with REW and see what it would look like. Either way, you've got a pretty good response there...

brucek

Thanks again.

Here is a plot of mains+sub.

My crossovers are:
mains = 60Hz
LFE = 80Hz

How should I adjust the crossovers?

Is there anything I should correct?

Here's 2 more plots with both mains and sub.

The first is with the mains' crossover at 40Hz.

The second with the mains' crossover at 80Hz.

I think the 80Hz is better as the peaks are lower. Is this correct?

Also, why is there a big dip wherever I set the crossover? Do I need to worry about that?

[atledreier]

The dip is because the sub and mains are cancelling each other out at the crossover. Try playing with sub phase and/or distance to minimize it. It's a pain, but worth it.

Here's the sub+mains after some phase/distance changes:

I'm still looking for a good crossover point for my mains.

Sorry, here's the graph for the last post.

[brucek]

You might increase the level of the sub a bit..............

brucek wrote:

You might increase the level of the sub a bit..............

Ok, so I shouldn't worry too much about the peaks and dips that you see in that last graph? My crossovers are fine at that setting then?

[brucek]

It does seem that 80Hz offers the best response, so I'd leave it at that. There would be people who would say you should get a BFD parametric equalizer for that response, but there are tradeoffs when you equalize and your plot isn't really bad enough to warrant it in my opinion. You'll find the response changes when you move the listening position microphone even a few feet. You appear to have found a fairly good spot for the sub, so I don't know if I would do much more....

brucek

Thanks for all the great help.

Another question(s):

Can REW be used to calibrate the centre channel's freq response? If so, which input on the receiver would be used, as obviously the L or R inputs can't be. Would you use the Multichannel's centre input?

Again, it's more to just calibrate the receiver's internal equalizer for the centre channel, and ultimate also I'd like to do each surround.

My receiver has a rough equalizer for each speaker (63Hz, 160Hz, 400Hz, etc.) And of course for the sub (20Hz, 40Hz, 63Hz, 100Hz, 160 Hz), so it would be great if I could try to even out the response for each speaker, even though the main calibration is of course the sub and it's interaction with the mains.

Here is a before and after of my calibration work.

I still need to boost the sub a bit.

(Edit: Sorry, I noticed the charts aren't on the same settings. I'll reedit it tonight when I'm home.