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Old 21st February 2011, 07:21 PM   #431
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If you are getting the same result with or without anything patched into the card then it would seem that the noise problem is with the card itself. I note that your loopback measurement is at nearly -20db, have you tried different levels for output and input? (My card is fairly sensitive to getting these right).

Have you tried RMAA Download. Audio Rightmark will only give you loopback type measurements but would be interesting to see the noise graph produced by a different program, and should show whether there is an inherent noise issue with your card itself

Also DBMandrake gave me some very useful advice (specifically for my card, an Audigy II ZS) and that was to quit all programs that might use the sound card for any reason (if you have a sound card and on board sound as well, then enable the onboard, and set it to be the default for playback and recording). Itunes was apparently a particular problem. The other one was to ensure that the sample rate you are using is one that is natively supported by your card.

I think you should concentrate on the soundcard rather than the phantom power for the moment

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Old 22nd February 2011, 08:11 AM   #432
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Quote:
Originally Posted by jtalden View Post
Since you have the MiniDSP there is no reason not to fine tune the phase handoff of your setup. The mic should be on axis and back from the speaker far enough to minimize the relative distance error between the drivers and close enough to avoid excessive multipath issues. You may want to try about 2 m back and move closer if needed.

Assuming your graph reflects this type of setup the phase can be improved for both the W-MR and the MR-TW XOs. The dotted phase curves should overlay as much a possible through the acoustic XO ranges or from about 200-450 Hz and 1.8k to 4k Hz.

Note that the W phase at the 380 Hz acoustic handoff is about 40 deg and the MR is about 180 deg. This is a 140 deg differential. If you delay the MR more relative to the W the two curves will overlay much better. For the MR-TW the phase curves are closer, but can still be improved a little. The TW needs a little less delay relative to the MR for the best match.

Your system can be setup within 10 to 20 deg throughout the XO ranges with some fine tuning of the delays.
Thanks for the response, I didn't realise you had posted it until today, I follow the threads through the "List Subscriptions" which usually shows me any new post in the thread I have been in but occasionally it doesn't. There is an Australian forum that does that all the time, a bit of a pain really.

I am challenged when it comes to phase response, I understand the concept (mostly) but really have trouble interpreting the charts. I will be getting back to that side of things as soon as I tidy up a couple of other projects that are taking WAY too long. the prototypes I have built still need a bit of work & I am going to give another mid a run as well.

Thanks again

David
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Old 22nd February 2011, 09:42 AM   #433
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Originally Posted by wintermute View Post
I think you should concentrate on the soundcard
Which sounds fair.

I went out and bought a brand new sound blaster. I de-installed Holm, deleted the user directory with the cal files and saved plots, restarted the computer and opened no other program, installed Holm, calibrated via loopback with the output and recording levels on full, then took this plot with no cables connected to the card.
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Old 22nd February 2011, 10:31 AM   #434
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Wait!

Please disregard the last plot. The problem is fixed. (The settings were defaulting to the mic input and the card doesn't have one). Noise floor is better than -80dB.

So it was a bad card. I seem to blow up a lot of sound cards (two so far this year).
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Old 22nd February 2011, 10:44 AM   #435
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Good to hear it's sorted! I bet you had a sinking feeling when you got that first plot....

What have you been connecting to the cards? Your mic phantom power isn't putting out +- 5V or something with high spl levels is it?

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Old 22nd February 2011, 11:06 AM   #436
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Umm, it may be because I'm one of these types that never switches anything off before reconfiguring, but I can sense the risk on a case by case basis. Although I am safety conscious, I've always felt that perfectionism stifles creativity, hehe. Anyway, who wants to be switching amps on and off when playing around line level? I could have blown up a lot more.

I do think soundcards are needlessly frail. I may have to connect a buffer of some sort. I don't want a full preamp though, just a protective buffer.

Last edited by AllenB; 22nd February 2011 at 11:09 AM.
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Old 14th March 2011, 07:58 PM   #437
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Friends, anyone has a microphone calibration file for the ECM8000 for use with the HOLMUmpulse?, I have several and have a lot of difference whether and not which one to use

Regards
Osvaldo
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Old 14th March 2011, 08:10 PM   #438
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You need to have a file specific to your ECM8000. i have 3 calibrated ones and the curves are all different

dave
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Old 15th March 2011, 11:33 AM   #439
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You need to have a file specific to your ECM8000. i have 3 calibrated ones and the curves are all different

dave
Is something better than nothing?

david
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Old 15th March 2011, 12:07 PM   #440
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Is something better than nothing?
I think so. I looked around and came to an intuitive guess with my cal file...a downloaded generic one that was claimed to be an average of dozens of real cal files.

Looking at my measurements, the correction just felt right...or at least a good step in the right direction. Better still, it sounded like a good step in the right direction.

I suggest you think about what you expect you should be measuring above 2kHz and look at your results, after studying the form of some correction files. You'll probably develop the feel I'm talking about.
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