Soundcard Cal - pulling my hair out!!

**strange_brew** · **12-06-07, 01:05 PM**

This is my 2nd go round with REW. I have a BFD and have downloaded filters to it previously. I even got to the point where I was playing with House Curves and was pretty happy with the results. But I recently put a riser into my HT room and want to revisit my settings as it doesn't sound as good as it used to.

But I can't for the life of me get anything to work. I used the exact same setup as before and had a variety of weird things happening. I decided to go back to basics and start from scratch with the soundcard cal. And that is where I am stuck.

When I put the loopback in and do the calibration measurement, I get the expected response.

But then, when I try to measure it to verify things are working, I get this - a flat line (good) but at 111 dB (bad):

Then I check the SPL meter and it shows ~48 dB with the loopback connection on and nothing else connected! The problem is the same when I try to measure anything - its like I have a floor of 50 dB in all my measurements and its driving me crazy. I thought maybe it was a ground loop putting a buzz into the line inputs, so I disconnnected all other cables. Still no joy.

I have also made sure that the recording monitor is muted and REW is the only program running.

I'm guessing my onboard soundcard must be shot. But it seems hard to believe since I haven't really changed anything.

Does anyone have any ideas? Brucek?

**brucek** · **12-06-07, 02:24 PM**

Quote:

But then, when I try to measure it to verify things are working, I get this - a flat line (good) but at 111 dB (bad):

Looks good to me. You simply forgot to press the Set Target Level button........................

Just follow the normal routine of Check Level, Calibrate SPL meter, Set Target Level, Measure.....

brucek

**strange_brew** · **12-06-07, 03:01 PM**

I wish it were that simple. When I try to set the target level, this is what I get:

The first 2 possibilities (AV processor volume and SPL meter range) don't apply since I'm testing the soundcard cal with the loopback still hooked up, and the sweep level is at -12 dB.

**brucek** · **12-06-07, 05:25 PM**

Try Delete All the Settings button and start over................. it must be something simple..

**JohnM** · **12-07-07, 02:51 AM**

You just need to do the SPL meter calibration, and make sure that when you do it you have a good signal coming in from the meter. If, for example, you were to go through the meter cal process but the meter was off or set to a very high range or the cable had a bad connection REW would treat the very low signal it was getting as being the 75dB level (assuming you cal at 75), then when a correct signal is fed in e.g. your loopback you get a very high SPL reading. Your best sanity check is the VU meters, as they show you signal levels relative to the maximum range of the soundcard. If you have a sensible level on the VU meter but the SPL reading is way off, redo the SPL meter calibration.

**strange_brew** · **12-07-07, 10:16 AM**

Thanks Guys!!

Brucek - delete settings did it.

JohnM, thanks for the explanation. You were absolutely correct, and now I know why Deleting the settings worked.

So back to business. As I suspected, things were a little off kilter. But the BFD has worked its usual magic and I got a pretty good result.

I punched up my House Curve a little too:

20, 7
80, 0

Do you think its too aggressive?

Next I'll test the integration with the mains. It still doesn't seem to have the "oomph" I want so maybe that's why...

Craig

**strange_brew** · **12-07-07, 10:54 AM**

Here is the response with the mains on. No wonder it doesn't sound too good.

I could have sworn I set the Mains to "small", but I'll recheck.

**strange_brew** · **12-07-07, 11:07 AM**

Yep, mains are on small and x-over is set at 80Hz

**brucek** · **12-07-07, 12:23 PM**

Lower the level of the mains (or raise the sub) and then play with the phase a bit to clear the big dip below the crossover..........

brucek

**strange_brew** · **12-07-07, 03:12 PM**

Ok, started from scratch. All BFD filters off, notch filter in Pre/Pro off

Then I bumped up the Sub amp volume and did 10 different tests with the Phase knob. Best result was at about 5% shift:

Then I reapplied the BFD filters and adjusted the sub amp vol as necessary. This is about the best I could do. What do you think? No matter what I do I can't get rid of the dip around 73 Hz. Should I worry about that? Is there anything else I can do? Move the cross-over maybe?

**brucek** · **12-07-07, 05:35 PM**

Looks pretty good to me......... Does it sound OK? better / worse ?

brucek

**clubfoot** · **12-08-07, 08:05 AM**

Try moving the sub, seating location or mains. I would do a REW sweep of the mains first by themselves looking mainly at the bottom end,....did you adjust the distance of the sub or mains?

**strange_brew** · **12-09-07, 08:41 AM**

Quote:

brucek wrote:

Looks pretty good to me......... Does it sound OK? better / worse ?

brucek

I haven't had a chance to do a lot of testing yet, but it seems a little smoother than it was. I'm just wondering if, by the graph, there are any obvious problems. Sounds like it is probably a good starting point for listening tests?

Quote:

clubfoot wrote:

Try moving the sub, seating location or mains. I would do a REW sweep of the mains first by themselves looking mainly at the bottom end,....did you adjust the distance of the sub or mains?

I can't move the seating location. And the Sub/speakers are behind my screen so I can only move them laterally across the front, not front to back. Is there any way to tell if this is a length mode? If it is, I don't think there is much I'm going to be able to do about it.

These pictures might help visualize what I'm working with. The Sub is in the center, directly behind the screen. The mains are just inside the sides of the screen (screen is acoustically transparent)

**clubfoot** · **12-09-07, 06:08 PM**

Beautiful theatre,...looks as though you're going to need a BFD to fine tune the sub since you cannot move it.

**strange_brew** · **12-10-07, 08:31 AM**

Quote:

clubfoot wrote:

Beautiful theatre,...looks as though you're going to need a BFD to fine tune the sub since you cannot move it.

My last set of results are with the BFD installed

**clubfoot** · **12-10-07, 01:10 PM**

Quote:

strange_brew wrote:

My last set of results are with the BFD installed

Oops, my bad. Did adjusting the sub phase or distance help reduce the dip?

P.S. Just realised you're in Oakville!

**strange_brew** · **12-10-07, 02:42 PM**

Quote:

clubfoot wrote:

Oops, my bad. Did adjusting the sub phase or distance help reduce the dip?

P.S. Just realised you're in Oakville!

Ok, I played around with it again on the weekend and here is where I ended up:

Sub only - BFD Filters on:

Mains only - no filters

Mains and Sub - BFD filters on, Pre/Pro Notch filters on, phase at optimal

I thought it looked pretty good, so I did a bunch of listening tests primarily with movies. And while it sounds ok, its lacking a bit of the hit you in the chest "oomph" that I'm looking for.

I also used my pre-pro to listen to it at frequencies between 20 Hz and 120 Hz. It seems reasonably even to my ear, so I'm not sure where the "hole" in the sound is, or if its just my perception. Any thoughts? Is my house curve too shallow?

**clubfoot** · **12-10-07, 06:41 PM**

If you take another measurement a little forward and back of where you sit, does it look any better or worst?

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