# Rew Setup few questions about sweeps.



## porksoda (Feb 25, 2010)

Hiya,

I recently setup rew on a machine and i have spent some time reading a lot of threads here to give me pointers which helped a lot. I was able to get the soundcard cal done and connected to my cheapy radio shack digital meter as well i have done a few sweeps and got the graphs. 

I find i am getting clipping when i run the sweep for speakers at -12db so i changed the level to -14db at which level i am getting no clipping at 128k, but getting clipping at 256,512 and 1mb.

Is there something wrong with my setup or its a limitation of my hardware or radioshack meter?

1 - Here is the Calibration for soundcard via loop.
2 - Here is my Sweep for my bookshelf speaker with spl meter at ear level:
3 - Same sweep smoothed:
4 - I had done a few more sweeps with longer lengths and here is an avg with smoothing:


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## tonyvdb (Sep 5, 2007)

Hi Porksoda, Welcome to the Shack!

You wont be able to post graphs until you have 5 posts as per the forum rules You can use the post padding tread to achieve this.


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## porksoda (Feb 25, 2010)

tonyvdb said:


> Hi Porksoda, Welcome to the Shack!
> 
> You wont be able to post graphs until you have 5 posts as per the forum rules You can use the post padding tread to achieve this.


thanks. I kinda figured that since i posted and no graphs showed up so i just attached them instead.


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## tonyvdb (Sep 5, 2007)

Recalibrate your SPL meter making sure that the reading that shows up in the REW window matches the meter and make sure that you have C weighting checked on the second page of the setup. 
Also repost your graphs with a 45-105 dB vertical axis, and limit the low end to 15 Hz and the top range to 10kHz


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## porksoda (Feb 25, 2010)

tonyvdb said:


> Recalibrate your SPL meter making sure that the reading that shows up in the REW window matches the meter and make sure that you have C weighting checked on the second page of the setup.
> Also repost your graphs with a 45-105 dB vertical axis, and limit the low end to 15 Hz and the top range to 10kHz


I will post the new Graph again but i just ran a quick sweep it shows up as same... the C weighting is checked... i am using RadioShack-33-2055-4050-CS.cal for my radioshack correction file.

I already set the vertical axis to 45-105db for the above posted graphs.


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## tonyvdb (Sep 5, 2007)

Are these graphs just full range with no sub?


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## porksoda (Feb 25, 2010)

tonyvdb said:


> Are these graphs just full range with no sub?


yup only bookshelf speaker right now... was going to perfect the setup and then move to the room with sub.


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## tonyvdb (Sep 5, 2007)

Well, with the Radio shack meter the readings above 4K are not very accurate however you do seem to have a good sized peak at 7kHz and another at around 175Hz. You need to address those first.


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## porksoda (Feb 25, 2010)

tonyvdb said:


> Well, with the Radio shack meter the readings above 4K are not very accurate however you do seem to have a good sized peak at 7kHz and another at around 175Hz. You need to address those first.


thanks. 
My main question/concern was in relation to my setup i wanted to make sure i understood and did things properly. 

I just have one speaker in just a room for just testing my rew setup and is not my usual listening spot.

One was the issue of clipping that i experience if i set the level to -12.. -14 i get no clipping at 128k length another higher i get clipping...

once i setup the rew then i will measure my 2ch and my ht system.


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## tonyvdb (Sep 5, 2007)

turn down the volume on the speakers just a little bit until the clipping stops you should be fine Make sure that your not running the soundcard volume to hot as well. On my laptop I run my master at only 1/4 of the way up.


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## porksoda (Feb 25, 2010)

tonyvdb said:


> turn down the volume on the speakers just a little bit until the clipping stops you should be fine Make sure that your not running the soundcard volume to hot as well. On my laptop I run my master at only 1/4 of the way up.


hmm... i guess thats where i need some help as the documentation for rew said to set wave volume to 1.00 and output volume to 0.500 which is what i set it as. Also when loopthrough calibration i found the best equal-ish volume for input volume for me was 0.912.

Those are for loopthrough and i set those levels throughout my active sweeps or those settings were only valid for rew loopthrough soundcard cals?

The above sweeps i ran through the same settings 1.00/0.500 and 0.912 also amplifier's volume was increased until the spl meter read 75db for the calibration part.


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## tonyvdb (Sep 5, 2007)

This is where I am not so knowledgeable, I am sure that one of our members who knows what is best will chime in soon. I know what worked for me wont always work for others and REW is a very powerful tool if set up properly but the initial setup can be quite frustrating to some.


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## porksoda (Feb 25, 2010)

tonyvdb said:


> This is where I am not so knowledgeable, I am sure that one of our members who knows what is best will chime in soon. I know what worked for me wont always work for others and REW is a very powerful tool if set up properly but the initial setup can be quite frustrating to some.


thanks... i will wait for someone else to chime in.


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## Wayne A. Pflughaupt (Apr 13, 2006)

If you're clipping, it's fine to reduce the receiver's volume.

Regards,
Wayne


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## porksoda (Feb 25, 2010)

Wayne A. Pflughaupt said:


> If you're clipping, it's fine to reduce the receiver's volume.
> 
> Regards,
> Wayne


thanks.

I guess my understanding is lacking on how rew sets reference level pre calibration so it knows whats going on.

I ran a few more sweeps and i was wondering:

- Before any calibration is done what needs to be set to have a "reference" I am assuming the Level check as long as signal is between -24 and -12 db its good... so i set it to around -18db.

- After i set levels obviously the next is to calibrate rew to get a baseline so it knows where meter is... so i turn the receivers volume till it hits 75db and my calibration is done.

After this point i can run sweeps.

- If i do move the position of the spl meter obviously the above two need to be done again before another sweep is to be taken?


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## Wayne A. Pflughaupt (Apr 13, 2006)

> - After i set levels obviously the next is to calibrate rew to get a baseline so it knows where meter is... so i turn the receivers volume till it hits 75db and my calibration is done.


After you get the receiver to 75 dB, you have to enter “75 dB” in the box. _Then_ calibration is finished.




> - If i do move the position of the spl meter obviously the above two need to be done again before another sweep is to be taken?


No, you only need to re-calibrate the levels if they change – like after equalizing for instance.

Regards,
Wayne


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## porksoda (Feb 25, 2010)

Wayne A. Pflughaupt said:


> After you get the receiver to 75 dB, you have to enter “75 dB” in the box. _Then_ calibration is finished.
> 
> 
> No, you only need to re-calibrate the levels if they change – like after equalizing for instance.
> ...


thanks.

I will do some readings in my ht room and post the graphs and see if they make sense.


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## porksoda (Feb 25, 2010)

Guys,

I did a few sweeps of my living room from my prime position.

Room only i.e no noise from amp unsmoothed.










Room only i.e no noise from amp smoothed.










In room response with front speaker + sub @ 80hz xover unsmoothed.










In room response with front speaker + sub @ 80hz xover smoothed.










In room response with front speaker + sub @ 80hz xover unsmoothed w/ PEQ filter applied.










In room response with front speaker + sub @ 80hz xover smoothed w/ PEQ filter applied.










In room response with front speaker + sub @ 80hz xover unsmoothed. Before peq and after peq.


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## Ricci (May 23, 2007)

Is your room square, or does one dimension L,W,H = half of another dimension?

You may want to try moving the sub around. You've got 2 very large peaks at 24 and 48hz which are an octave apart, which is why I asked the above.


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## porksoda (Feb 25, 2010)

Ricci said:


> Is your room square, or does one dimension L,W,H = half of another dimension?
> 
> You may want to try moving the sub around. You've got 2 very large peaks at 24 and 48hz which are an octave apart, which is why I asked the above.


I did measure the room its a perfect square. I used the crawl method to find the best position for the sub and this is it... do you recommend moving it ... because while i used the crawl method i found this location to be best.

I was able to use the peq to reduce the peak at 49.2hz as you can see its reduced but not flat.

I did some new sweeps with sub alone and speaker alone and all together... will post them later.

Another question i have is does it mater what length of tone i use for the sweep i find for the sub 128k, 256k and 1mb seem to work best but 512k gets unpredictable.


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## porksoda (Feb 25, 2010)

Ok so i have finally calibrated the sub and this is probably as good as it gets for me without getting a sub eq.

I have done final graphs for Sub only then Tower only with and without smoothing and waterfalls...

I will just post the final results unsmoothed, smoothed and the waterfall.

thanks for everyones input and help.


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