Came across an interesting little problem yesterday. I was with my band recording a few songs to update our demo material and for some reason it took a long time to get a bass sound the engineer was happy with. I started out with the Fender Bassman valve head and 412 cab that I used at the same studio last year, but despite using the same Fender Jazz I had with me last time, the sound was weak, muffled and slightly distorted.
I had my own gear in the car, so we changed the battered 412 for my Barefaced Super Twin, The sound improved, but there was still some unwanted distortion. Next we brought in my Ashdown ABM 500 and (reluctantly) replaced the Bassman. Very little improvement. I changed the Jazz for my Precision. Still distorting, and some odd clicking sounds as the notes decayed. Same clicking sounds when we swapped back to the Bassman, and with both amps when i used the Jazz again.
By now, we had used up an hour or more of precious studio time just getting the bass right. Finally we simply decided to use my amp, my cab and my speaker lead, and suddenly the sound was fine. Quick check revealed that the culprit was the studio's speaker lead.
The final bass sound was a mix of miked up Ashdown/Barefaced and DI from the amp to desk. We still managed to record five songs without overrunning!