- Aug 10, 2008
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If you want an 'all tube' amp, buy a Mesa. Nearly all their amps use tube rectification.
Have you actually read any of the information posted in this thread yet?
Tube vs Solid State Rectifiers
The job of the rectifier is to convert alternating current (AC) which comes out of the wall socket and subsequently the power transformer, into direct current (DC), which is needed to operate all of the circuitry in the amplifier. This process takes place through a device called a diode. Diodes act like a one way valve, allowing current only to flow in one direction.
The diodes in the days of old were vacuum tubes. Today's diodes are made out of silicon.
The tube diode was the first diode ever invented (in fact it was the first tube ever invented). For many years it worked quite dependably, and it was the only choice for rectifying current for high voltage power supplies. When solid state technology was developed in the 1950's, it was found that solid state diodes could do the job of tube diodes, only better.
A tube rectifier has internal resistance. The more current that travels through a tube rectifier, the more the voltage drops. When the voltage drops, the power of the amplifier also drops. The tube rectifier has the drawback of not being able to provide a consistent voltage when it's under load. The other drawback is that the tubes themselves run hot, and can be relatively short lived. Unfortunately, modern day sources for rectifier tubes are not very reliable, and even in their prime these tubes were usually the weak link in most amplifiers.
An amp with a tube rectifier tends to sound much "spongier" in the bottom end. Low frequency notes take more current through the power tubes to reproduce. This increased current causes a voltage drop in the rectifier tube and the amp loses power. So, when more power is actually needed, the amp gives less. Because of this, a tube rectifier amp will sound spongy and more distorted at high volumes. This, probably more than anything, is what gives a vintage amp its sound and color.
A solid state rectifier has no internal resistance whatsoever. It has a very consistent fixed voltage drop that occurs whether there's no current or full current - approximately .7 volts. When an amplifier needs power at low frequencies, there will be no limit to the current that travels through the rectifier. This results in an amp with more headroom that is punchier, more articulate, and able to deliver the goods in the bottom end.
In my opinion, all amps should have solid state rectifiers. I don't believe there are any really good rectifier tubes on today's market and, even if there were, why use them? The technology is obsolete, they are horribly inefficient, and far more expensive and troublesome to build into an amp. These tubes, no matter how good, will routinely need replacing, adding to your maintenance expenses. Besides that, tube rectifiers kill the headroom of an amplifier. If you want that spongy, vintage sound, there are other ways to do it. I have successfully designed and built amps that have replicated that soggy bottom, vintage tube rectifier sound using solid state rectifiers and various circuit modifications.
Of course if you have a vintage amp that uses a tube rectifier, by all means keep it that way! That's what makes it sound the way it does. But if you're contemplating getting a new amp, I recommend avoiding future headaches by staying away from tube rectifiers.
Good, neither do I....At any rate, I've heard good amps with tube rectos and without, I don't feel strongly either way.
Whatever . I was trying to cut through the hype. There is a bunch of marketing hype out there about valve rectifiers, class A amplification, AlNiCo magnets in speakers, NOS valves, etc, etc.But, you obviously have a point to prove, so I'll go and let you.
Mike Soldano's take on this topic...
Soldano: If you want that spongy, vintage sound, there are other ways to do it.
An electronics engineer might be able to explain the differences which us guitarists perceive as better tone in a tube amp.
For starters, any digital amp (like processors, digital amps) will have an A/D converter that samples the input signal with a fixed sampling rate. That puts limitations on the maximum frequencies (harmonics) of the signal. Guitar pickups generate harmonics, which might be killed at the input of the amp/digital processor.
Tubes, because of their physical characteristics, generate harmonics when pushed outside of their operating curves. Since it's all analog circuit, there is no nyquist rate playing a part.
Also, analog components like tubes have their individual capacitances/inductcances/transconductance which change as the tubes heat up. It is near impossible to mimic these on a DSP chip.
Members here will attest to the fact that when you play an amp and the tubes start heating up more, say after half an hour, the amp of the tone changes from what it was when the tubes were cold.
That's ultra lo-fi tube technology for you, my friend
Again, this would be one of the 100 factors that give tube amps the sound that they have.
The important point is we all love them. Though SS amps are becoming more popular as technology advances, those little glass thingies will always have a place in our hearts, and in our amps !
You betcha, hipo.
Jimmy Vaughn ended up with all of SRV's gear.
I wonder if he still powers up those old amps.
If he ever puts them on the market, you'll likely see a feeding frenzy beyond words.
Marshall moved to SS rectifiers in the 1960s. Fender did likewise in the 70s. Most of the Brit manufacturers did, too.