getting ready for REW couple questions.

[adamanteus]

hi guys,

lurker here and first time poster. i'll try to be brief as i am on my way out the door to work.

i'm expecting the BFD any day now, along with the edirol midi cable and in anticipation i'm trying to get a feel for REW on my PC setup and sub (onix x-sub), before the BFD gets here and i move on to my main system. i'm an ex pc tech and electronics geek but i am a little bewildered here.

first thing the equipment i'll be working with once i figure REW out- streamlined to what i'm calibrating with:

pioneer elite 81 receiver.
svs 25-31 pci tuned to 22hz
radioshack SPL meter (on a budget getting married in november)
turtle beach santa cruz pci sound card (little outdated but havent had a need to upgrade...yet)
BFD SP1124P

my first issue is with the sound card (santa cruz) i would have thought it would be more than adequate. however i am having a tough time calibrating it. it seems to do fine when i use the default measurement settngs in REW but when i try to calibrate with non default- ie- speakers, mic- i keep getting a clipping error message. does anyone else use this card? any advice if you do? i'm trying to avoid purchasing the SB usb due to fundage for above mentioned wedding.

my second question is fairly simple- i think . if all i am interested in is EQ'ing my sub can i just run the sound card (assuming i straighten that out or buy an SB usb) straight into the analog sub input (in the analog multi channel in section) on my pioneer and output all tones 80hz and below through it and my svs?

thanks for the program it seems awesome and i'm sure i'll figure it all out. i just hope to speed up my learning curve and practice on my pc sound system while i await the BFD. theoreticaly if i can figure it out then when the BFD gets here i can just knock it out.

again thanks for any advice and i'll check in later from work.

-A

[Otto]

First of all -- hello and welcome to the Shack!

my first issue is with the sound card (santa cruz) i would have thought it would be more than adequate. however i am having a tough time calibrating it. it seems to do fine when i use the default measurement settngs in REW but when i try to calibrate with non default- ie- speakers, mic- i keep getting a clipping error message. does anyone else use this card? any advice if you do? i'm trying to avoid purchasing the SB usb due to fundage for above mentioned wedding.

So were you able to do the soundcard cal using a simple loopback cable? Just use the audio out to the line in (most likely with a 1/8" to 1/8" stereo cable). If you got past that OK, there's no reason that you shouldn't be able to use REW to measure speakers. Who is it that's complaining about clipping? Is it REW or the soundcard that's somehow complaining? If it's REW that's complaining that you have clipped (it was probably some type of "Headroom" message, but I've never hit that), you should be able to avoid that type of scenario by simply turning down the volume on your receiver/pre/pro. Did you "Calibrate" the SPL level that's received by REW and what's shown on your SPL meter? That, too, should get you to avoid this problem. Also, if you are going "in" on your soundcard's "mic in", you might have these types of problems. Be sure to use "line in".

I think I have that soundcard in an old machine that I use rarely for audio, and never for REW. If it has a "line in" input (and I'm pretty sure it does), I don't think there should be a problem using it with REW.

my second question is fairly simple- i think . if all i am interested in is EQ'ing my sub can i just run the sound card (assuming i straighten that out or buy an SB usb) straight into the analog sub input (in the analog multi channel in section) on my pioneer and output all tones 80hz and below through it and my svs?

In general, you could do that. But you'll get more benefit from just going in on a "normal" L/R input (e.g., the "CD" input or the "Aux" input, etc.). The mono signal will be redirected to your sub as dictated by the bass management of your receiver. Then, once you have the sub all nice and EQ'd, you will be able to simply reinstate your mains and remeasure to ensure that the sub and the mains blend properly, especially around the crossover point. With this type of setup, the signal sent to the sub should still roll off at 80 Hz (or whatever crossover point you set in your Pioneer).

Good luck!

[brucek]

my first issue is with the sound card (santa cruz) i would have thought it would be more than adequate. however i am having a tough time calibrating it. it seems to do fine when i use the default measurement settngs in REW but when i try to calibrate with non default- ie- speakers, mic- i keep getting a clipping error message

Not allowed to use the mic-in. You need to use line-in............ the Radio Shack meter outputs line level.....

brucek

[adamanteus]

thanks guys. will play with it more this weekend. the santa cruz does have a line in. when i leave REW in it's defualt position for measuring soundcard it does fine on the loopback but, if i mess with the settings and say change it to speakers and line in- rew complains of clipping.

so if i do part one of the help file- calibrate sound card then go to part 2 and leave the loop in place to run a sample (faux) sub measurement (sorry if my reply is confusing- still at work) in REW default soundcard settings all goes well. but if i mess with the default settings i get the clipping message in REW. maybe i'm better off just leaving it in default if it is working?

[adamanteus]

well, got the soundcard calibrated and first impressions so far on REW w/ the BFD are very positive!

i have a couple questions . my xover on my receiver is set to 80hz. my sub extends to 22hz. should i be measuring between say 15hz to 80hz? and also do you guys use the auto filter settings? measure the sub a few times correct and then go with the best result or do you manually tweak? i have not messed with manual tweaking yet.

[brucek]

should i be measuring between say 15hz to 80hz?

Nope. Measure to 200Hz. REW will start its sweep from 2Hz. Set your graph Axis with a vertical scale of 45dB to 105dB and a horizontal scale from 15Hz to 200Hz.

do you guys use the auto filter settings? measure the sub a few times correct and then go with the best result or do you manually tweak? i have not messed with manual tweaking yet.

Normally you would let REW first choose the filters for you and present its corrected results. If you feel you can do a bit better (and that's usually the case), you would either (or both) alter the suggested filters a bit and add your own to end up with the corrected graph that you like. Be sure to click the Optimize PK Gain and the Adjust Pk Gains buttons after you do so to readjust the corrected graph...

brucek

[adamanteus]

thanks alot. for whatever reason measuring to 200hz made a bg difference and made it much easier for me to smooth out the sub. it sounds really good now . not perfecty flat but i have a few room issues (dips) i need to straighten out (pun intended) that i cant get the BFD to correct. but so far the difference is huge .

[adamanteus]

ok another quick question- if i am disconnecting all my speakers except for the sub when adjusting/ measuring; what benefits am i getting by measuring up to 200hz whne my xover on the sub is at 80hz? i'm only asking for knowledge and understanding.

also should i follow the house curve chart on the graph or should i calibrate it flat? my receiver has a built in house curve setting.

also how can i bypass the eq to get an accurate measurement? my BFD did not come with a manual- i bought it used.

i'm sure i'll have other questions, some of which may be very trivial...

thanks.

[Otto]

adamanteus wrote:

ok another quick question- if i am disconnecting all my speakers except for the sub when adjusting/ measuring; what benefits am i getting by measuring up to 200hz whne my xover on the sub is at 80hz? i'm only asking for knowledge and understanding.

It allows you to see the cutoff slope, which will determine how it will blend with your mains. You should be able to see it nicely follow the target curve. Although your crossover frequency may be set to 80 Hz, it's not as if the sub's output just instantly stops at 80 Hz. Generally, a fourth order low-pass filter is applied to the sub output, so it will roll off at 24 dB/octave.

also should i follow the house curve chart on the graph or should i calibrate it flat? my receiver has a built in house curve setting.

The use of a house curve, or not, is up to you. It's something to play around with -- see how you like it, how it sounds for you, and then use what you prefer. Some of us create two settings in the BFD -- one flat and one with a house curve, generally for music and movies, respectively.

As to your receiver's built-in house curve stuff -- I generally tend to skip any kind of proprietary processing that's in a receiver or preamp. I like to keep things as straight as possible. However, if they've done a good implementation, it may be a benefit for you. I would probably measure it, and listen to it and see how you like it. I think that feature is going to be personal preference as well.

also how can i bypass the eq to get an accurate measurement? my BFD did not come with a manual- i bought it used.

In the upper right corner of the BFD's bank of buttons is one marked "In/Out". If that light is on, then the filters are engaged. If it's off, you are doing a straight pass through on the BFD (though it may be doing A/D/A on the signal anyway; I'm not sure on that detail). All this type of stuff is explained here in the BFD Guide. The BFD manual is here.

i'm sure i'll have other questions, some of which may be very trivial... thanks.

Sure. Hope that helps. Good luck!

[adamanteus]

thanks for all the help. that really cleared it up. little by little i'm really getting the sub to sound great. i think it's almost there. the program is actually quite easy to use. my main issue was setting the graph correctly and targets etc.