Recent Probems wit Winamp

It's all about the equipment

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Mr Awesomer
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#16 Post by Mr Awesomer » Wed Jul 21, 2010 7:47 pm

keither wrote:Piece. Of. Junk.
I've got oscilloscope shots somewhere, if you want me to post 'em.
For a Swing DJ it's perfectly fine. We all know people dancing at the local VFW to underpowered speakers that are way to small for the room anyway aren't going to hear the difference between a cheap USB soundcard and the higher end card.
Reuben Brown
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keither
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#17 Post by keither » Wed Jul 21, 2010 9:34 pm

In general, I would agree with that, however I found the output of the cheapy USB sticks distorts as the volume goes up. That distortion results in clipped peaks on the output. Those clipped peaks dump extra power into the speakers and can damage them. (Power is the area under the curve, so if you have a square wave, there's a LOT more power than under a clean sinusoid.)

It's not an audio fidelity issue, it's actually an equipment damage issue that concerns me. The headphone out on my laptop, while quieter, doesn't show that issue. The line out on my Indigo doesn't show it either.

You're probably safe if you keep the output volume on the USB stick to a level where a sinusoid won't distort, but you'd have to scope each individual stick to find out what that point is.

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#18 Post by Mr Awesomer » Wed Jul 21, 2010 10:34 pm

I've used one (the older model) for years, on a variety of systems, from concert venues to the multitude of dreaded setups described above and everything in between, without a single issue. I've also seen plenty of other DJs using the exact same device. I don't need to see a bunch of charts and graphs to know it's an imperfect device, and I'm sure under just the right circumstances it could potential create some problems. I'm not arguing that it's not a piece of junk, it's cheap, but again, for what we do, it's perfectly fine.
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keither
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#19 Post by keither » Thu Jul 22, 2010 5:00 am

The issue is a shortening of lifespan of the speaker systems you plug into. Sure, for a few hours here and there, it's probably not a big deal. Over the life of the system, it can significantly reduce the operational lifespan.

You can drive a car in 1st gear all the time and never see an issue, but the life of that car will be greatly reduced over one where the gearshift was used as intended.

Like I said before:
You're probably safe if you keep the output volume on the USB stick to a level where a sinusoid won't distort, but you'd have to scope each individual stick to find out what that point is.
Being aware of a potential issue and mitigating it (in this case, by reducing the volume on the USB stick below 100%) is a lot different than saying there isn't one because anecdotally you didn't see it.

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#20 Post by SoundInMotionDJ » Thu Jul 22, 2010 6:51 am

keither wrote:In general, I would agree with that, however I found the output of the cheapy USB sticks distorts as the volume goes up.
It is true that cheapy USB sticks distort as the signal approaches the limits of the device. But so do cheapy mixers (think anything in the <$1000 range), and so do cheapy EQ's, and cheapy crossovers, etc.

Until a few years ago, ANY external sound card, including the $20 Turtle Beach cards, are better than (almost) all built-in sound cards in laptops. In the last couple of years, laptops have started to include 24 bit sound cards built-in...this changes the level of the playing field a little.

I use the Gigaport AG USB sound cards I bought almost 10 years ago...so quality external sound cards last a long time with even a little bit of care.

After an external sound card is added, it is likely that there is some other link in the total signal chain that is the weakest (my generic bet is on unbalanced signal connections, then mixer quality, then long speaker cable runs).
keither wrote:That distortion results in clipped peaks on the output. Those clipped peaks dump extra power into the speakers and can damage them. (Power is the area under the curve, so if you have a square wave, there's a LOT more power than under a clean sinusoid.)
Specifically, the area under a clean sine wave is 0.707 times the peak value (e.g. sqrt(2)). A proper square wave has an area of 1 times the peak value, or an increase of just over 40%.

Any music will sound worse and worse the more the signal is increased...and by the time a full square wave is achieved, the sound will be completely awful. (But I know better than to assume that anyone can actually hear that distortion AND correctly identify the cause in the middle of a gig.)

This is why every sound system should have a hard limiter setup just before the amps to ensure that no signal ever exceeds the thermal capabilities of the speaker cabinets. It might sound crappy, but at least the speakers will be protected.

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#21 Post by keither » Thu Jul 22, 2010 7:33 am

SoundInMotionDJ wrote:This is why every sound system should have a hard limiter setup just before the amps to ensure that no signal ever exceeds the thermal capabilities of the speaker cabinets. It might sound crappy, but at least the speakers will be protected.
Isn't that kind of at odds with the whole $20 USB stick thing? :)

The sound system I installed at the Fed uses balanced connections from the mixer all the way through the signal chain, and includes a dbx DriveRack 260. Unfortunately, it fails at the actual speakers which are old and need to be replaced.

Of course, at that point, my mixer has a USB input, so you can skip the cheapy USB stick entirely.

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#22 Post by SoundInMotionDJ » Thu Jul 22, 2010 7:41 am

keither wrote:
SoundInMotionDJ wrote:This is why every sound system should have a hard limiter setup just before the amps to ensure that no signal ever exceeds the thermal capabilities of the speaker cabinets. It might sound crappy, but at least the speakers will be protected.
Isn't that kind of at odds with the whole $20 USB stick thing? :)
Not necessarily. Generally the person with the $20 USB stick and the person with the PA system are different people. One of those people will probably be waaaaaay more interested in protecting the speakers from being given too much power than the other one of those people. :wink:

The limited dynamic range of the $20 USB stick is probably not something that actively crosses the mind of the person who buys the USB mixer, and the DRPA, and the balanced signal cables...but sometimes it does.

When I setup a PA system, there is NO combination of inputs from the DJ that can harm the speakers. 8)

Unfortunately, there are many combinations of inputs from the DJ that will sound crappy. :roll:

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