bikehorn
04-10-2008, 04:31 PM
I read about this trick on DIY audio...so I tried it for myself. I took two 5 ohm 10w non-inductive resistors and put them in parallel for 2.5 ohms and 20 watts. With my 35 wpc Superscope this was plenty of power dissipation capacity for a large safety margin.
The idea is to raise the power amplifier's output impedance to resemble that of a typical tube amp, which affects the damping factor. Supposedly Bob Carver used it in a few of his solid state amps and in blind tests fooled a lot of experienced listeners into thinking they were hearing tube amps. I'm not an expert, maybe one of the residents here on AK can correct me if I'm wrong.
It doesn't magically make a bad sounding amplifier sound good, and it also doesn't necessarily make your amp sound "just like a tube amp". Bob Carver engineered those amps fairly thoroughly and the output impedance is just part of the tube effect. Let's not forget the fact that it also depends on the speakers you are using. It's a try it and see thing, and ultra cheap, like a few bucks for a couple of resistors. Some people will say that inserting resistance in a speaker lead is defeating the purpose of having high grade speaker cable. I'd just say, don't knock it till you try it.
I haven't gone back since adding them. My Wharfedales powered by my Superscope sound fuller, the bass sounds more relaxed and something about the treatment of voices changed definitely for the better. I tried it with my friend's B&W DM220s driven by his Technics SA-300 and while voices again seemed to become clearer the bass definition was compromised...so it may not work for you but it just might.
Anyone out there doing this? And liking it?
The idea is to raise the power amplifier's output impedance to resemble that of a typical tube amp, which affects the damping factor. Supposedly Bob Carver used it in a few of his solid state amps and in blind tests fooled a lot of experienced listeners into thinking they were hearing tube amps. I'm not an expert, maybe one of the residents here on AK can correct me if I'm wrong.
It doesn't magically make a bad sounding amplifier sound good, and it also doesn't necessarily make your amp sound "just like a tube amp". Bob Carver engineered those amps fairly thoroughly and the output impedance is just part of the tube effect. Let's not forget the fact that it also depends on the speakers you are using. It's a try it and see thing, and ultra cheap, like a few bucks for a couple of resistors. Some people will say that inserting resistance in a speaker lead is defeating the purpose of having high grade speaker cable. I'd just say, don't knock it till you try it.
I haven't gone back since adding them. My Wharfedales powered by my Superscope sound fuller, the bass sounds more relaxed and something about the treatment of voices changed definitely for the better. I tried it with my friend's B&W DM220s driven by his Technics SA-300 and while voices again seemed to become clearer the bass definition was compromised...so it may not work for you but it just might.
Anyone out there doing this? And liking it?