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Old 29th June 2012, 08:45 AM   #641
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looks great You might also want to check what the native sampling rates of your card are. That looks like you have 44.1Khz sampling, but most cards are native 48, 96, 192... you are best off running at a native rate, so might be better setting to 48Khz sampling rate.

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Old 29th June 2012, 09:30 AM   #642
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You're right. It is 48KHz sampling rate for this sound card. I'll change it immediately.



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Quote:
Originally Posted by Pano View Post
You're welcome! Glad you got it.

Just remember that the RCA outputs are about 4dB hotter than the max input level to the mic input. It's a common problem in audio, connecting a too hot line level into a mic input.

Last edited by Zvu; 29th June 2012 at 09:35 AM.
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Old 29th August 2012, 09:00 AM   #643
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Hi folks.

I'd like to calibrate my system.

I have got an EMU 0404 USB. It measures pretty flat from analog-out to analog-in. I can't make use of it tough.

I'm using a full digital amp (DDX320) in the chain.

Measurement loop:

EMU-digital-out -> Toslink-> DDX320 -> ?? ->EMU-analog-in

What am I supposed to do?

I'd need to take the amp output as reference.

What's the best way to do that??

Thx
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Old 29th August 2012, 12:53 PM   #644
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Calibration of your soundcard is straightforward--simply follow the prompts in Holm on the "device and Signal tab." This will generate a correction which is automatically applied to subsequent measurements to offset any sporty behaviour on the part of your computer audio..

I have measured the amplifier output by attaching a shielded cable to one of my channel (left or right) speaker cables and feeding the signal back into the microphone input of the Holm setup. This is pretty risky because everything is interconnected via the ground/shielding circuitry which means you could be applying far too much power. Proceed with very low gain settings and at least a small blocking cap or best of all an isolation transformer. What you should get is a typical Holm graph that shows the variations in gain thru your audio power system. I don't know of any way to introduce this as a true calibration signal into Holm's mysterious calculations but you can show it on every output graph as a reference against which to eyeball-gauge speaker responses.
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Old 29th August 2012, 01:13 PM   #645
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I've done the standard - pretty straight forward - calibration - as I mentioned.

So. What your saying: Turn down the signal to 2VRMS (limit of input) on the amp output and loop it back in !?!?!?
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Old 29th August 2012, 02:29 PM   #646
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Quote:
Originally Posted by soundcheck View Post
I've done the standard - pretty straight forward - calibration - as I mentioned.

So. What your saying: Turn down the signal to 2VRMS (limit of input) on the amp output and loop it back in !?!?!?
Yes--you simply treat the amplifier output as though it was a microphone signal or a line-level input (I think your EMU 0404 soundcard has a line level input). Also reduce the amplifier output to a low value to avoid overdriving the computer. But you must be careful when you feed back to your computer from the speaker terminals because the shielding system connects all of your computer and audio equipment together on one side. Try to trace thru the circuitry from your amplifier ground to determine which side of the speaker cable is the ground side and connect that side to the shield side of the cable which runs to the computer microphone input. And insert a capacitor or, preferably, an isolation transformer in the circuit from speaker terminals back to sound card line (or microphone) input. Or you could do as I have done namely cross your fingers and go for it. But understand that you might damage your computer input circuitry.
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Old 29th August 2012, 03:24 PM   #647
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Gotta differential Class-D amp. No ground. Line-in is also differential
on my EMU.

How would I connect these to the xlr?

amp+ > p2, amp- >p1, p3=open?
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Old 11th November 2012, 12:13 PM   #648
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This thread hasn't been active for awhile. So, I thought I'd 'wake it up' a bit with a question regarding interpretation of impulse response data.

I know there is much information in those first few squiggles at and beyond 0 ms. If a squiggle is up or down, then up and up or up and down, etc... You know what I'm getting at.
What does each mean?
Any help in prior posts in this thread or other threads someone could direct me to?
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Old 21st November 2012, 01:18 PM   #649
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Quote:
Originally Posted by speakerdoctor View Post
This thread hasn't been active for awhile. So, I thought I'd 'wake it up' a bit with a question regarding interpretation of impulse response data.

I know there is much information in those first few squiggles at and beyond 0 ms. If a squiggle is up or down, then up and up or up and down, etc... You know what I'm getting at.
What does each mean?
Any help in prior posts in this thread or other threads someone could direct me to?
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Old 21st November 2012, 01:21 PM   #650
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