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Hmm, I am starting to wonder if perhaps this is not something the Empeg people or one of us should build something for.

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Absolutely! There is so much possibility with the empeg. It's a general purpose computer with a microphone input, moderately flexible hardware DSP, infinitely flexible software DSP, and plenty of processing power. There is a world of possibilities for auto calibration in both the frequency and time domains. I'm sure Empeg has thought down these lines though it's not easy to do correctly.

-Dylan

Edited by georgelsjr on 15/10/00 06:34 PM.

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I'm in the process of ripping the waves into MP3's again, since I found sound artifacts in the ones I downloaded

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I'd be curious to know if you find a way to encode them better. I used LAME at it's maximum bit rate and highest quality setting. Everything I've read says that LAME is the best encoder available.

-Dylan

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I played a few of the mp3's on my system and heard some breaks, so I listened to the wave files and didn't hear them.

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Can you (or anyone else) tell me which tracks? I've not yet listened to all of the MP3's but I haven't heard any problems on the ones I have listened to. I'll re-encode any that have problems.

-Dylan

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Hmmm, since so many of us seem to be downloading these would someone be willing to create a howto for using them for those of with limited tuning experience?

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This is what I did. I welcome other ideas for how to best do this. I have some familiarity with this topic but am far from an expert.

I used the 1/3 octave band tracks (10-40) along with an SPL meter in an attempt to equalize the db reading at each frequency band. I selected a volume level on the empeg that was about my usual listening volume then I quickly went through the octave bands to establish a rough average db level. This also gave me an idea up front where the major problems were in my system. (I was pleased with myself that the guesses I'd made by ear were in the ballpark.)

I don't have any real procedure I can give. I pretty much just went through all of the 1/3 octave bands and identified the frequencies where I needed to make corrections. It was a trial and error process of determining which frequency I should use for each band and what the adjustment and Q needed to be.

I think the best approach would be to record the reading for each 1/3 octave and then graph it out. That will make it easier to choose the 5 or 10 bands to adjust. Probably the thing to do is pick the frequency that is at the peak of each hump or dip. With the empeg's flexible Q setting you should be able to dial in the proper slope for each hump/dip.

I didn't set up any special playlist other than having the tracks in CD order. It was a hassle switching back and forth between the equalizer and controlling the track being played. What I wanted when I was doing this was to have a repeating loop of 3 or 4 bands so I could just stay in the EQ menu. So when I try this again I'll set up playlists to accomplish that. (Will the player cycle to the beginning of a playlist or will I need to explicitly repeat the tracks in each playlist?)

The SPL meter I used and the one that is ubiquitous in the home theater world is Radio Shack Cat.#: 33-2050. It's an analog meter that costs $35. Don't get the more expensive digital meter as it's less accurate. Here is some information on the RatShack meter. Do a search at Google and you'll find more interesting links.

After typing up this post I see some things I can do better. I figured that I'd end redoing it after learning from my first attempt. I think that by plotting out the results, applying the corrections for the meter inaccuracy, and putting some forethought into it I should get better results. That being said, I'm thrilled already with the improvement I was able to make. I put new speakers and a new head unit in my car when I got it last year. I'd intended these to be the first steps towards a great system but I was so disappointed in the sound quality that I gave up. The acoustics in my VW Passat Wagon are lousy. I have some enormous frequency anomalies that could not be corrected with the course adjustments in my head unit. The EQ in the empeg allowed me to make it much, much better. Now I'm excited again about the system in my car.

This is all a bonus as far as I'm concerned. I bought the empeg because I wanted all of my music in my car at my fingertips. I knew of the EQ but it wasn't a factor in my buying decision. I'm pleased as punch!

-Dylan

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EXTREMELY slow or flakey connections with both the original FTP as well as George's mirror

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I have no idea why it would be extremely slow or flakey. My logs confirm that I've been maxing out my 384 Kb DSL connection for most of the past few days. Many people had long, uninterrupted sessions and achieved throughput of 15-30 KB depending on how many concurrent sessions there were.

The site has been down today, however. I needed the bandwidth for other purposes.

-Dylan

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I ripped and encoded a CD called Sound Check from the Alan Parsons Project. It's called a "Professional Audio Test Disc" and it's got lots of test tones and other tracks to help in calibrating a sound system.
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Send an email to audiotest@theginsburgs.org for ftp instructions. That's an autoresponding address so I won't see anything you write.

Please heed the warning in the email about track 59.

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I've just retrieved these files from the web mirror at http://www.bstage.com/AudioTest/ (thanks, dewdman42!).
Where is track 59? It's not on the mirror, and the autoresponder is no longer responding, so I don't know what the warning said.

Cheers,
- Sean

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I don't suppose someone could put these some place accessable to us all?

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