Tube Amp Warmth

I've been reading about tube amps and the warmth of the sound they produce. Will a tube amp work with an A/V receiver if there is a digital amp already in the receiver? It seems to me that it wouldn't because the sound has already gone through a digital amp and you can't get back to the original quality.

Bob Spencer

Some A/V receivers do indeed have digital amplifiers, but many others have analog amps that use solid-state circuitry, and audiophiles argue endlessly about the sonic difference between digital, analog solid-state, and analog tube amps. In general, tube amps do have what is normally characterized as a "warm" sound due to the predominance of second-order harmonics.

Most modern AVRs have preouts—that is, outputs from the preamp stage of the signal path—that can be connected to tube-based power amplifiers for those who want that warm sound. In this case, the signal does not pass through the AVR's power-amp stage, so the signal is not being "double amplified," which should never be done no matter what type of power amps are being used.

If you want use tube amps for their warm sound, it's probably better to get a preamp/processor rather than an AVR, since you'd be paying for amplifiers in the AVR that you won't be using. But keep in mind that tube amps are generally pretty expensive, and their output power is relatively low, so you need high-sensitivity speakers. And if you're powering a surround system, you'll need several tube amps, since there are few if any 5- or 7-channel models available.

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Boken's picture

I'm a guitarist as well as an audiophile and I never understood why I could get a top of the line Marshall Tube Amp head for $2200 but its hard to find a tube power amp for less than $5000. There's nothing like the sound of a tube amp for my guitar and I would love to have tube amps for my home theater but I don't have that kind of cash. Is it just because the market is smaller for analog tube amps or is there that much of a difference between a 100 watt Marshall tube amp and a 75 watt McIntosh tube amp?