REW and AVR only

[augmont]

In two days i'll be taking my first measurements with REW. I only have an AVR (entry level Onkyo) - no amps, pre-amp, etc. what will i be able to do once i measure my room? Perhaps i had higher expectations on ability to "tweak" my system but after reading a few posts, i'm not so sure anymore. Speakers and sub locations are pretty much fixed due to WAF.

I have Infinity Primus 360's as L/C/R, 150's for surrounds, and a Rythmik 15" sub (DS1500). I just completed the sub which is why i'm wanting to use REW.

[JohnM]

If your DS1500 is driven from a sub output on your AVR then you would have the ability to put an equaliser in the path to the sub to apply some EQ to it, if your measurements showed that would be beneficial.

You could also use your measurements to
- find the best place to sit if you have some choices over seating
- see if there are strong reflections from walls or floor that are degrading the sound and could be helped by a rug or some (fairly) unobtrusive wall panels at the first reflection points
- check whether your speaker distance alignments are set correctly
- check whether your speaker levels are set correctly
- check whether your sub polarity is set correctly
- check whether your sub level is set correctly

[augmont]

First Measurement. Please critique. the dip is at 44.4hz

[brucek]

Please critique

Please use the standard axis we use at the Shack.

Vertical axis scale = 45dB-105dB
Horizontal axis scale = 15Hz-200Hz

brucek

[Wayne A. Pflughaupt]

First Measurement. Please critique. the dip is at 44.4hz

Hopefully you can try another location? This one is not working well.

I assume this is subs and mains together, since there appears to be no signal drop above 80 Hz or so? If so, make sure your mains are set to “small.”

Regards,
Wayne

[augmont]

Wayne A. Pflughaupt wrote:

Hopefully you can try another location? This one is not working well.

I assume this is subs and mains together, since there appears to be no signal drop above 80 Hz or so? If so, make sure your mains are set to “small.”

Regards,
Wayne

It was only the sub. looks like i need to retest and figure something out. Where should my connection on the AVR from the soundcard should be? I used the CD input

[brucek]

Where should my connection on the AVR from the soundcard should be? I used the CD input

Yeah, CD or AUX is good....

brucek

[augmont]

Wayne A. Pflughaupt wrote:

Hopefully you can try another location? This one is not working well.

I assume this is subs and mains together, since there appears to be no signal drop above 80 Hz or so? If so, make sure your mains are set to “small.”

Regards,
Wayne

The crossover is 80hz and speaker set to small. Is the reciever not doing it's job? On the end Freq, i set it at 200hz? should that be changed? Should I unplug my mains (i thought i did but really can't remember)?

[Wayne A. Pflughaupt]

augmont wrote:

The crossover is 80hz and speaker set to small. Is the reciever not doing it's job?

Well, you noted in post #6 that it was a “sub only” graph. I assume that means you did not have the receiver in the signal chain at the time. The receiver can’t “do its job” unless it’s in the signal chain... Using the CD or AUX input will put the receiver in the signal chain.

On the end Freq, i set it at 200hz? should that be changed?

If you’re referring to the graph axis, 200 Hz is fine.

Should I unplug my mains (i thought i did but really can't remember)?

Typically recommend graphing the sub first, then adding the mains, but that’s if you’re equalizing the sub. Since you’re not doing that yet, it doesn’t matter.

Regards,
Wayne

[brucek]

Should I unplug my mains (i thought i did but really can't remember)?

Yeah, if you want to do a sub only measure - and you should.

It's just a good idea to disconnect the mains and get a look at the sub itself through the receiver with the crossover set..

It's also a good idea (even though you're maybe not equalizing), to set the proper target crossover in REW to 80Hz also. You have yours up around 120Hz I believe (from looking at your graph). It makes no difference at this point, but it's nice to see if the sub tracks the 80Hz target line on the graph or not. It's all about gathering information. If you see that you have a perfectly tracking sub and then the sub + mains is wacky, you know where the problem lies......

brucek

[augmont]

Wayne A. Pflughaupt wrote:

Well, you noted in post #6 that it was a “sub only” graph. I assume that means you did not have the receiver in the signal chain at the time. The receiver can’t “do its job” unless it’s in the signal chain... Using the CD or AUX input will put the receiver in the signal chain.


If you’re referring to the graph axis, 200 Hz is fine.


Typically recommend graphing the sub first, then adding the mains, but that’s if you’re equalizing the sub. Since you’re not doing that yet, it doesn’t matter.

Regards,
Wayne

Sorry, I meant that i was "attempting" to measure the sub only. I hooked up the sound card to the receiver's CD input. Your observation of no drop off after around 80hz means 1.) my mains were in the mix when "attempting" to measure only the sub, 2.) i did something wrong. I think it's both.

Question: if i retest, unplug my mains, reverify speakers are set to small and crossover 80hz on the reciever, i should get roll off at/near 80hz? If i don't, then is my problem with my sound card and/or REW settings, or bad receiver?

[augmont]

brucek wrote:

Yeah, if you want to do a sub only measure - and you should.

It's just a good idea to disconnect the mains and get a look at the sub itself through the receiver with the crossover set..

It's also a good idea (even though you're maybe not equalizing), to set the proper target crossover in REW to 80Hz also. You have yours up around 120Hz I believe (from looking at your graph). It makes no difference at this point, but it's nice to see if the sub tracks the 80Hz target line on the graph or not. It's all about gathering information. If you see that you have a perfectly tracking sub and then the sub + mains is wacky, you know where the problem lies......

brucek

Bruce,

in looking at my target settings, it was at 80hz. What am i not seeing or missing up?

[brucek]

Question: if i retest, unplug my mains, reverify speakers are set to small and crossover 80hz on the reciever, i should get roll off at/near 80hz? If i don't, then is my problem with my sound card and/or REW settings, or bad receiver?

The latter.............

in looking at my target settings, it was at 80hz.

Really? OK, I'll take your word for it.

Here's what an 80Hz target looks like on my computer.

You can see I'm down -6dB at 80Hz. You're not. You're only -3dB down. Hopefully you have a slope of 24dB/octave set?

80hz.jpg

brucek

[augmont]

brucek wrote:

The latter.............


Really? OK, I'll take your word for it.

Here's what an 80Hz target looks like on my computer.

You can see I'm down -6dB at 80Hz. You're not. You're only -3dB down. Hopefully you have a slope of 24dB/octave set?

Attachment 7080

brucek

I set the slope at 12db/octave. It's probably due to my misunderstanding of the Rythmik kit i have. I order the sealed 12/bd/octave subwoofer kit since that's what they recommend we using an AVR and so i thought i needed set the graph at 12 bd/octave. sounds like the two are not related.

[brucek]

The setting of the 24dB/oct slope in REW is matching it against the receivers crossover setting of its low pass filter (LPF). The standard is 24. This is the slope at which it rolls off the sub out high frequencies just as you see in the target diagram above in my previous post.

The sub itself will have its own internal LPF shut off in this case so as not to interfere with the one set in the receiver.

brucek