# Trying to get REW figured out



## KristiSwallow (Nov 25, 2006)

I've just stated trying to learn how to use Room EQ Wizard. I've calibrated the sound card and set levels but when I go to measure the sub, graph looks way different than I expected. Please see the attachment.


The sound card is plugged directly into the DSP1124p. What am I doing wrong?

TIA! 

Kristi


PS: Largest peak found was 27.7 dB


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## JohnM (Apr 11, 2006)

The measurement looks OK. As you are plugged directly into the sub via the 1124P the effective roll-off will be much higher than if going through a receiver, which is why the output isn't dropping like the target curve. You can try setting the target cutoff frequency to its highest value or use a flat target. Also worth changing the graph scales to the 15..200Hz and 45..105dB defaults. Is your sub next to a wall or in a corner? If not, putting it in a corner should help lift the low end somewhat.


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## brucek (Apr 11, 2006)

> graph looks way different than I expected.


As John says, your graph axis is not correct. Axis can exaggerate and distort a response so it's almost unreadable.

Set vertical to 45dB-105dB and horizontal to 15Hz-200Hz and it will look like you expected. 

To set the scale, use the Graph Limits icon in the top right hand corner of REW. Once you enter the limits, they will be there the next time you pop up the icon.

brucek


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## Bent (May 24, 2006)

Kristi, I'm not sure if everyone here is familiar with your hardware (it's been a while) - are you still using the 4 -18" Mach-5 mj-18's in an IB and the EP-1500 Berhringer?


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## KristiSwallow (Nov 25, 2006)

Thanks for the suggestions, I'll adjust the axis tonight.

Bent was right (thanks Ben!) about my hardware (4 -18" Mach-5 mj-18's in an IB and the EP-1500 Berhringer?) The IB is in-wall, centered below the screen.

I thought that perhaps the reason for the highest peak @ 27.7 dB might be because of the built in filters on the DSP1124? I haven't done anything with the EQ...just plugged it in and set the bottons on the back to -10dB.


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## brucek (Apr 11, 2006)

> I thought that perhaps the reason for the highest peak @ 27.7 dB might be because of the built in filters on the DSP1124?


Press the IN/OUT button on the BFD front panel and the Green LED will go out. This bypasses all filters.


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## KristiSwallow (Nov 25, 2006)

Okay, I'll re-run the test when I can and make sure the IN/OUT LED is off. then I'll adjust the axis and repost. Thanks for the suggestions so far! Might have to wait until the weekend tho... stay tooned!:nerd:


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## KristiSwallow (Nov 25, 2006)

one more question before I re-run the test. Would it be better to go through the Reciever than connecting the sound card straight to the EQ?


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## brucek (Apr 11, 2006)

> one more question before I re-run the test. Would it be better to go through the Reciever than connecting the sound card straight to the EQ?


Yes, because then you will have the receivers crossover activated. Be sure that the receiver is in the stereo mode with no effects or soundfields on.

Best to disconnconnect the mains and do a sub only measure first. After EQ, add the mains and test for integration of the sub and mains at the crossover area.

brucek


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## KristiSwallow (Nov 25, 2006)

After implementing all the suggestions you all made, here is my new measurement. Is this a little more normal?...now I just have to read the help file and figure out the next step.


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## KristiSwallow (Nov 25, 2006)

Okay, I'm not really sure how to progress from here. The REW help files tell me how to use the midi interface to program my BFD, but not having a midi interface, what is the next step? I've found the peaks and assigned filters in REW, optimized PK Gain and Adjusted PK Gains. Where are the numbers that I need to program the BFD manually?


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## imbeaujp (Oct 20, 2007)

Hello, your frequency respomse below 40hz seems problematic to me, considering you have 4x18 inches drivers and a good amp. Is it possible that some of your driver are not well connected ? I meen in phase ? I do not know much about Infinite Baffle so all input from other shackster will be useful.

JP


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## KristiSwallow (Nov 25, 2006)

Did the AA battery test and the subs are in phase. Gonna get a nearfield plot on the weekend.


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## KristiSwallow (Nov 25, 2006)

Thomas from Cult of the Infinately Baffled has given me some pointers and here is my latest measurement. 


How do I take this data and turn it into filters for the BFD? Is this what "Find Peaks" in REW does?


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## brucek (Apr 11, 2006)

> How do I take this data and turn it into filters for the BFD?


Read the REW HELP FILES under Filter Ajustment

brucek


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## Bent (May 24, 2006)

I'd start at the ugliest peak - 50 Hz, apply a 10dB cut 1/10 octave BW, and re-plot it, just to get a feel for how the BFD affects change. You may miss it entirely, or you may see a marked improvement.


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## Bent (May 24, 2006)

oops, I see you are running REW in it's complete form - you are waaayy ahead of me...


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## Sonnie (Apr 11, 2006)

To me that looks like pitiful low end response... no disrespect to your sub, but what sub do you have and where is it located?


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## KristiSwallow (Nov 25, 2006)

Its an Infinite Baffle Sub (4 -18" Mach-5 mj-18's, Berhringer EP-1500 amp, DSP1124) The IB is in-wall, centered below the screen.

Does this look better?

Turns out the Amp had a low cut filter I had to turn off.


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## imbeaujp (Oct 20, 2007)

Yeh ! Much better for the 10 to 30 Hz range! 

It seemed very strange to me that you do not have a good output in that range... That's why I asked you is the 4 drivers are in phase.. I did not think about a low pass filter because I do not have one on my amps.

But now your graph is more "normal" and you just have to apply some filters on the big peaks. The 50 - 60Hz zone seems to be the critical zone. You should lower that. I would also try a little "boost" in the 30 - 35 Hz area but remember to not add more than a few dB.

Have fun!

JP


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## KristiSwallow (Nov 25, 2006)

Does this seem like too many filters?


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

Kristi,

Prodigious output in the upper frequencies like you’re seeing seems to be typical for an IB sub. You might want to take a look at this thread (especially from my post and below). In that thread I recommended to the OP that an analog electronic crossover could be beneficial in taming the upper frequencies, which would then make equalization much simpler.

Regards,
Wayne


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## imbeaujp (Oct 20, 2007)

Hello, all filters with a bandwith less than 3 are useless. I think that filters 5, 6, 7, 8 and 9 simply do nothing, you can remove them (try this, and you will see).

Try to use more bandwith on your filters, 4/60 is a minimum.

Hope this helps !


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## KristiSwallow (Nov 25, 2006)

Wayne A. Pflughaupt said:


> Prodigious output in the upper frequencies like you’re seeing seems to be typical for an IB sub. You might want to take a look at this thread (especially from my post and below). In that thread I recommended to the OP that an analog electronic crossover could be beneficial in taming the upper frequencies, which would then make equalization much simpler.


If I'm understanding that thread properly, my upper bass is coming in louder than my lower bass so I want to cut it out completely. Is this correct?


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## KristiSwallow (Nov 25, 2006)

imbeaujp said:


> Hello, all filters with a bandwith less than 3 are useless. I think that filters 5, 6, 7, 8 and 9 simply do nothing, you can remove them (try this, and you will see).
> 
> Try to use more bandwith on your filters, 4/60 is a minimum.
> 
> Hope this helps !


I'll keep that in mind when I make the adjustments. Thanks!


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

KristiSwallow said:


> If I'm understanding that thread properly, my upper bass is coming in louder than my lower bass so I want to cut it out completely. Is this correct?


Not cut it out completely, just reduce it so that it’s more in keeping with the Target. An outboard crossover connected between the receiver and subwoofer (preferably in front of the BFD) would easily accomplish this. However, you could also do it with the BFD, by applying very broad and deeply cut filters centered somewhere above say, 250 Hz. 

Are the above graphs showing before or after EQ?

Regards,
Wayne


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## KristiSwallow (Nov 25, 2006)

Wayne A. Pflughaupt said:


> Not cut it out completely, just reduce it so that it’s more in keeping with the target line. An outboard crossover connected between the receiver and subwoofer (preferably in front of the BFD) would accomplish this. However, you could also do it with the BFD by applying very broad filters and deeply cut filters centered somewhere above say, 250 Hz.
> 
> Are the above graphs showing before or after EQ?


All the graphs are before EQ. Hope to have time to setup the filters on the BFD soon!


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## Bent (May 24, 2006)

Kristi, the output that you are measuring at frequencies above 80 hz seems funny (funny, in that they are even there - let alone measurable.)
Do you know if your crossover frequencies on your Yamaha AVR are correctly selected? (is your YPAO - or whatever Yamaha calls their automatic room equalization system turned off?)

The AVR should be sending minimal levels - if any at all, above 80 hz (assuming you chose 80 hz as your initial crossover) to the '1500, so it looks to me like you might either have the AVR sending these frequencies to the BFD, or the room is contributing with sympathetic resonances (are you doing your test sweeps at a high relative level and making the house "shake"), or another possibility - your measurement equipment might be a bit off. 

did you do these previous sweeps with your mains connected?

an outboard crossover between the receiver and the BFD will only show a change if the sweeps you've already posted don't include the outputs from the main speakers.

Either way, it looks like the deep bass is starting to shape up. I hope you are enjoying this and not finding it too tedious.


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## KristiSwallow (Nov 25, 2006)

KristiSwallow said:


> All the graphs are before EQ. Hope to have time to setup the filters on the BFD soon!





Bent said:


> Kristi, the output that you are measuring at frequencies above 80 hz seems funny (funny, in that they are even there - let alone measurable.)
> Do you know if your crossover frequencies on your Yamaha AVR are correctly selected? (is your YPAO - or whatever Yamaha calls their automatic room equalization system turned off?)


 The Crossover is set at 80, but I did use YPAO to setup the speakers. I'm not sure how to turn this off... when I do the measurements I set it to 2-channel stereo. I tried the pure-direct settings but this turns off the sub.




Bent said:


> The AVR should be sending minimal levels - if any at all, above 80 hz (assuming you chose 80 hz as your initial crossover) to the '1500, so it looks to me like you might either have the AVR sending these frequencies to the BFD, or the room is contributing with sympathetic resonances (are you doing your test sweeps at a high relative level and making the house "shake"), or another possibility - your measurement equipment might be a bit off.
> 
> did you do these previous sweeps with your mains connected?
> 
> ...


In order to get the input level high enough to do a measurement in REW, I have to set the Sub level on the receiver to + 10 and the sweep in REW to +3. My measurements are with the main speakers disconnected.


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## Bent (May 24, 2006)

Any luck?


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## KristiSwallow (Nov 25, 2006)

haven't had a chance to look at it yet  probably this weekend.


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## KristiSwallow (Nov 25, 2006)

okay... so it's been a while and I haven't made any progress. Does anyone know how to put a yamaha rx-v2600 into a non-eq 7.1 mode for calibration? Pure direct doesn't cut it a there is no sub output.


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## brucek (Apr 11, 2006)

> Does anyone know


Your receiver is to be set to stereo mode. 

This shuts off all the speakers except for the mains and sub with bass management. All other soundfield will be off.

brucek


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