DATE: Fri, 29 Jul 1994 19:40:17 CDT From: Barry Schaede Subject: More than anyone ever wanted to know about Fender Bassman Amps
The tweed 4-10 Bassman is an entirely different amp than the 50 watt silver face Bassman heads. The 4-10 Bassmans have pressence and middle controls that the heads lack. The 4-10 Bassman uses a 2 ohm output transformer that is interleaved and wound on a paper core. The silver face Bassmans use a 4 ohm output transformer wound on a plastic bobbin. The 2 types of transformers sound dramaticaly different to most ears. The tweed Bassman uses a tube rectifier that is unable to supply full current at peak demand and creates a sound in the output tubes known as sag. A much sought after phenomenon. The newer Bassman uses solid state diodes to rectify the current which results in a cleaner less distorted sound. The phase inverter circuit of the silver face Bassman uses a 12AT7 tube instead of the 7025 or 12AX7 used in the tweed version. The Output tubes of the siverface are 6L6GC's instead of the 5881's founds in the original Bassman. 5881's are a higher performance military grade of the 6L6 tube. They use gold in the internal conductors instead of the original silver used for the 6L6's and as a result have less output and lack the fidelity of the 5881's. Yes you could put 5881's into the newer Bassman but it still wouldn't sound the same as the 4-10. The silver face Bassman is probabaly a head. That is it lacks the built in speakers of the Tweed combo. This presents the problem of finding a cabinet that matches the impedance of the output transformer (8 ohms) and sounds good. What you'll probabaly find is 2-12 closed back cabinets. Not in my opinion a good sound for harmonica. You could try the Peavey 4-10 open back cabinet but you'd be running at a 100% impedance mismatch. Not a terrible thing to do but not the best thing to do. Oh one last thing the silver face Bassman has a deep and bright switch that the older version lacks. I've never been able to get a tone I like out of the newer Bassmans. Not so much because they're bad amps but more because they're more suited to guitar. Try the amp and if YOU like the sound buy it. After all if Lee Oskar can play through a solid state Roland bass amp and be happy anything's possible. FJM