What causes this?

[Billyo]

Hi all,

I'm planning the setup for my subwoofer build and thought that I'd run a few test tracks off Grooveshark through my main speakers to see how they responded to tracks that were deep into the sub zone.

e.g. this one

Sub Woofer Test by BASS TEST on Subwoofer Test | Grooveshark - Listen to Free Music Online - Internet Radio - Free MP3 Streaming

I find that behind the main track, there is a slight but audible high frequency whining that sounds a little like RF interference coming from the tweeters - I'd estimate the frequency was around 8000 Hz, but its not a pure tone , although it could just be resonating with the sub.

I don't think that its the track itself - since other similar tracks have the same sound. The sound is completely absent in 'normal' music.

The speakers I'm using is the Tony Gee LBS design and with a HifimeDIY TK2050 amp. The input to the amp goes through a Fiio D5 DAC from toslink.

Does anyone have ideas as to what might be causing this?

[revboden]

there is a odd midrange noise on the track link you posted. sounds like a compression artifact/ghost several octaves above the bass notes. could be that they scrubbed the bass line from a song and left some noise behind.

[Billyo]

Thanks for that.

Thats interesting - a lot of those similar subwoofer test tracks have the same whine.

[David_Web]

There is also a phase shift between L and R at lower frequencies. And some distortion.
Also, 32Hz isn't that deep.

I would use another track as it's very hard to determine low frequency behavior when there is distortion in the track. About 3.5% H2 distortion.

[epa]

Originally Posted by revboden

there is a odd midrange noise on the track link you posted. sounds like a compression artifact/ghost several octaves above the bass notes. could be that they scrubbed the bass line from a song and left some noise behind.

yep spot on

[bentoronto]

Hard for me to remember anything marked "test music" that was any darn good.

MP3, eh. I have some music sent via MP3. Sounds OK, kind of. But funny thing, my tweeter amp meter (north of 3200 Hz) shows barely anything up there.

Play stuff you are familiar with. I am lucky to have music I've listened to on many systems for test purposes for over half a century. And that includes bass sweep bands I've heard thousands of times.

Bit of a riddle trying to establish (and remember with your ears) what the "real" thing should sound like. Mahler's 8th played in your little living room? Organ of St John the Divine in NYC? Or even just a guitar. A riddle.

Ben

[Djim]

Sounds to me like a sine-wave bass with envelope clicking noises from a synth plug-in with a sample on top that follows the basline (accept when it plays a line) and a hi-hatt line from a virtual (or sample) Roland CR78 or 808 mixed in the box (recording software). No compressor used (and if only on the bass)