Poor technique = definitely.
I'm such a slide noob. This will be week 3. But I have progressed past the stage of being able to mute the non active strings - well, at least enough to be up to the standard of a home recording.
Compression = lots.
Just couldn't seem to get any even volume output without compression. There was always a sharp peak when I plucked a note and a very quiet "tail". Compression was the only way I could see to bring it all out evenly.
I was up quite close to the guitar with the mic.
You talk like you know how to do this jimistone. Is there a better way to record this slide?
Cheers,
FM
I'm not nearly as knowledgeable as others who frequent this sight on engineering a recording. Most of what I know I learned here or by trial and error. I have labored over a slide part though...much the same as you.
I usually put a sure SM58 on my amp speaker pointed toward the outside edge of the speaker...I also put a LDC mic above and in front of the amp (a couple of feet away...more than that and you have to deal with out of phase issues if you use both tracks). That gives me 2 tracks of guitar that have somewhat different sounds. Sometimes I will use an overdrive pedal sometimes I wont...depends on what sound I'm after.
I had the amp volume down and alot of compression on my first few tries and got alot of unwanted slide noise...like you did.
This is what worked for me:
I figured out that the massive compression was the greatest contributor to the noise. The recording was even....the noise was just as loud as the notes

.
So, after I got rid of the compression I had to crank the amp volume on up to get the sustain right.
Then with the amp volume way on up there and the sustain and tone sounding killer...I had to really work on my slide technique to get it right.
You see...with the amp volume turned up enough to make the "tails" sing forever you have to have very good touch with your picking hand on how hard to pick the string. You also need to be very good at muting because the volume makes everything that isn't muted ring out.
So, I say get rid of the compresser on the front end...crank your amp way on up...and work on your slide technique.
Compress the recording on in the mix if you need to tame dynamics. (if you develope the right touch you wont need to or want to compress very much in the mix)