Trouble getting started...

I'm all cabled up and attempting the soundcard calibration (Tascam 144), but can't get any further than "the 1kHz tone is now playing."

The REW input mixer/volume controls are not enabled, and the soundcard input and output level pods have no effect when trying to adjust the input levels.

Soundcard connections: Line out Right to Line/Guitar in Right (loopback)

[brucek]

What operating system and version are you using and what is the soundcard connection to the computer?

brucek

brucek wrote:

What operating system and version are you using and what is the soundcard connection to the computer?

brucek

I am using Windows XP Professional, version 2002, SP 2. The soundcard is connected via USB.
The soundcard (Tascam 144) is running driver version 1.11 and firmware version 1.11.

I just now discovered that the "Monitor Mix" control had to be set all the way clockwise to "Computer" on the Tascam, and the "Control output mixer/volume" had to be selected in the REW settings window, which now enables me to match the input level to the -12 dBFS output level.

Not sure though why these settings were necessary.

Does this look realistic for a soundcard cal ?

[brucek]

You do not want monitor or mixer functions turned on. It may appear that things work when they are on, but they simply loop the output to the input internally.

Does REW recognize the soundcard in the Settings page for Input and Output Device?

brucek

brucek wrote:

You do not want monitor or mixer functions turned on. It may appear that things work when they are on, but they simply loop the output to the input internally.

Does REW recognize the soundcard in the Settings page for Input and Output Device?

brucek

It's not clear how to be sure the monitor/mixer functions are off. The Tascam has a control knob that is "Input" when all the way counterclockwise, and "computer" when all the way clockwise. It only seems to let me adjust the input level in REW when it's set to "computer."

And yes, REW does recognize the soundcard on the settings page.

[brucek]

Can I see the REW settings page with it set the way you're using it.

(To capture a specific screen on the desktop, click the cursor in that screen and press Alt + PrtScr).

brucek

Settings window:

[brucek]

It actually looks fine. I looked at your manual and agree the MON MIX has to be CW over to the Computer to avoid any of the input being looped.

REW is not being allowed to control the input volume, but that's fine, you should be able to control it with the tascam application or go directly to the Windows Mixer (Recording). Be sure that line-in is deselected (muted) in the Windows Playback Mixer and selected in the Recording Mixer.

Any way you can show me the Windows Playback and Record mixers (double click speaker icon in systems tray and select record or playback in properties)

brucek

[brucek]

Line out Right to Line/Guitar in Right (loopback)

I trust you're using and RCA to 1/4" TS phone plug here, with the switch in the Guitar position?

brucek

brucek wrote:

I trust you're using and RCA to 1/4" TS phone plug here, with the switch in the Guitar position?

brucek

No, actually I've had the switch in the Mic/Line position. But I'll switch it to the Guitar position.

Not sure what you mean by "system tray", but here are my Windows audio settings...

[brucek]

Not sure what you mean by "system tray", but here are my Windows audio settings...

You got there by another route, but the little speaker icon in the bottom right hand of the desktop (where the time is) is the system tray.

Anyway, you're showing the Playback Mixer. Click the Options button there and then select Properties, and you can select the Playback or the Recording mixer, plus you can select the volume controls you want to be visible.

Here's a pic of my Record and Playback mixer and the correct settings......

PLAYBACK MIXER


RECORDING MIXER


See the line-in is Muted in playback.

Check that it's OK. Also see in the record mixer where you can control the volume input for line-in.

You didn't answer if you were using a RCA to 1/4" TS phone plug (not a TRS, but a TS).

But anyway, the feedback in your calibration file would likely have been caused by not having the switch in the high impedance unbalanced guitar switch position (or the cable being wrong).

Check that and try again.

brucek

Yes, I am using an RCA to 1/4" TS phone plug.

On my volume control panels (Windows mixer), I don't have the choices of "line-in" and "wave" like you do for the playback mixer. I only have those parameters shown in the mixer pics I sent (previous post).

Also notice that in my recording mixer, I have no parameter selections at all. Notice that my volume button under Sound Recording is grayed out.

[brucek]

OK, so you appear to have no software line-in control, but are you able to control the input level with the physical line-in control dial on the 144 itself?

Have you re-tried the soundcard cal routine with the switch position set to guitar?

brucek

Yes, I am able to control the input level with the Tascam dials.

Below is the soundcard cal results I get now with the input in the guitar position. Looks very similar to what I got before, except shifted in frequency. Does it look right ?

[brucek]

No, see the oscillations throughthe waveform. It appears as if you have some 'effects' turned on in the application software.

Search through all the settings for the card and be sure everything is shut off except for simple stereo.

I looked through the specs on the card in the manual and I see that the mic/line-guitar switch would actually be fine in the mic/line position (as it offers 10Kohm input impedance). I thought it may be a low impedance input and it is not - so you can go back to the mic/line position.

I can see nothing you are doing wrong except that you must have an effect turned on somewhere.

brucek

I've looked everywhere I know to look, and don't see any kind of effects even available for this soundcard.

The Tascam control panel allows settings for high, low and normal latency, it will let you set the Sample clock source to either automatic or internal, and you can set the digital output format to S/PDIF or AES/EBU.

There are no effects settings in the Windows Sounds and Audio Devices either.

I even tried taking the measurement after switching the soundcard to Mono, but it made no difference.

Can you suggest any places other than where I've looked, that might have effects settings ?

I noticed another poster, intelonetwo, was seeing the same kind of oscillation plot on his 6/6/08 post, but didn't really see what he did to correct it, other than pulling all cable connections out of the left channel.

[brucek]

Can you suggest any places other than where I've looked, that might have effects settings ?

I looked through the manual and don't see anything, so I can only suggest to try and get a cleaner calibrate file response by adjusting the sweep and input level. Usually the soundcard cal routine will work best when the sweep level is between -dB and -9dB (you're using -12dB). Then play with the input level a bit and test each change and observe the graph results. You're simply trying to stop that loop from osciallating. Below is an example of basically what you're looking for.

If you're successful, then save the file. To test if it works, then before removing the loopback, run a test measurement and you should get a perfectly flat response (because you're measuring a cable and the soundcard.cal file should compensate for the soundcards response anomolies).



brucek

brucek,
I found out what the "oscillations" are during my soundcard calibration attempts...

I monitored the 1kHz tone through headphones and heard a steady stream of dropouts...most are of short duration (a few milliseconds), but some are as long as one second. Next I tried taking a measurement, monitoring the 256k log sweep through headphones, and found a one-to-one correlation between the dropouts and the oscillation events seen on the resulting Filter Adjust plot.

I tried disabling all OS services (except Windows audio) using msconfig, but I still got the same quantity of dropouts. I also tried the whole cal/measurement procedure again through the soundcard's left channel, but saw the same dropout problem again.

I'm sure I could correct this problem if I could find a way to eliminate these dropouts during the 1kHz test tone.

Any suggestions ?

[brucek]

I'm sure I could correct this problem if I could find a way to eliminate these dropouts during the 1kHz test tone.

Yeah, I agree. Is your PC an older model that maybe can't keep its attention to the USB port?

I see in your manual they talk about performance:

Do not run other applications. You will probably use your computer for applications other than audio, but we recommend that you avoid running other applications at the same time you are running audio programs. Processing digital audio places a considerable load on your computer.
This means that if you are running other applications (especially graphics or Internet tools) at the same time as your audio application, the processing may not happen fast enough.
Certain devices such as network cards or WinModems can cause conflicts with USB processing. If you experience such a conflict, you can use the Device Manager to temporarily disable the offending device.
If your computer has an IDE hard disk, enabling Direct Memory Addressing (DMA) will improve performance. In Windows XP, this is enabled by default..

I have no problem on my laptop with VISTA and a USB external soundcard and REW. It doesn't seem that it is a very common problem, or others would have complained of this. Something must be running in the background. Hopefully you can track down the culprit.

I'm going to move this thread to the REW forum section to perhaps get more play...

brucek

I think I found the problem.

By trial and error mostly, I set the latency of the Tascam soundcard to the highest setting. The clicks/dropouts don't stop completely, but they're now down to about one every twenty seconds or so. Anyway, good enough to finally get a 'clean' soundcard cal measurement...I think !





The laptop I'm using is not all that old - 3 years - I think it should be fine for this application, especially now that I've turned off all unnecessary background applications.

[brucek]

Yep, that looks really good......... save it, and take a measure of the loopback cable with that soundcard cal file loaded (be sure to not have the SPL meter cal file loaded yet).

The result should be a flat line. Now that you'll be measuring, you'll use vertical scale of 45dB-105dB....

Then remove the loopback and hook up the SPL meter and receiver for real measuring...



brucek

brucek wrote:

Yep, that looks really good......... save it, and take a measure of the loopback cable with that soundcard cal file loaded (be sure to not have the SPL meter cal file loaded yet).

The result should be a flat line. Now that you'll be measuring, you'll use vertical scale of 45dB-105dB....


brucek

Here it is...



Can you help me understand the difference between the flat line at 110.1dB and the corrected and target curves down at 75dB ?

[HionHiFi]

brucek wrote:

Yep, that looks really good......... save it, and take a measure of the loopback cable with that soundcard cal file loaded (be sure to not have the SPL meter cal file loaded yet).

The result should be a flat line. Now that you'll be measuring, you'll use vertical scale of 45dB-105dB....

Then remove the loopback and hook up the SPL meter and receiver for real measuring...



brucek

Thats what I did to resolve the problem. That and copy the setting from your soundcard cal post. I haven't got back around to remeasuring with Audyessy engaged, maybe this weekend. Excited to see what the results will be.

At any rate, tickertape, now that your setup, and ready to go, what is your goal? What are you trying to achieve by using REW, and BFD.