How many tube amps have a damping factor of even 10 into 8 ohms, especially with 4 ohm speakers(halving the damping factor) that are so common today? I can only think off the top of my head of one tube amp with a high damping factor, the old Melos amps that had a damping factor of 20(unpublished Atkinson test). Every published Atkinson test of a tube amp I've seen(and I've been a subscriber since before Atkinson) shows substantial frequency variance with frequency.
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@dynamiclinearity I'm going with 'a fair amount'. The venerable Dyanco ST70 has a damping factor of about 15. This does not change with a 4 Ohm load since you'd be using the 4 Ohm taps. It would be cut in half if you ran a 4 Ohm load on the 8 Ohm tap. ElectroVoice made a number of tube amps (such as the A30) that had a damping factor of 15 back in the 1950s. It was EV and MacIntosh who came up with the idea of the amplifier being a Voltage source and the speakers being Voltage driven; this to enhance plug and play. Prior to that speakers had adjustments on the back (midrange and tweeter level controls) to allow the speaker to be adjusted to the unknown output impedance of the amp. The Mac MC275 had about 15:1. The Marantz 8b amplifier had a damping factor of 16:1. The famous Fisher SA100 was 20:1. FWIW no speaker made needs a damping factor of over 20. |
This has been my experience as well in terms of tube amps sounding more powerful, at least for their wattage. Maybe not all but certainly some that I have used.
Conrad Johnson premiere 12 tube mono blocks - 140w side.
I’ve had a very large variety of loud speakers in my room over the decades since I’ve owned those amplifiers , and they have been able to easily drive every single one of them, always sounding powerful. That includes even tough to drive Thiels and MBLs.
But once in a while, I try another solid-state amplifier in my system “ just to see.”
The last time I did it, I borrowed a Bryston 4B3 solid state amp (300 W into eight ohms, 500 into four ohms).
Just to take one example 1st : before I borrowed the Bryston amplifier one of the tracks I’ve been playing quite a bit was Basil Poledouris’ incredibly dynamic score for Conan the barbarian. Especially the opening track The Anvil Of Crom.
It’s performed by an augmented symphony, Orchestra , extra instruments, especially extra horns, and Timpany, and it’s just a massive, powerful charging sound. It had been blowing me away on my system .
So when I got the Bryston amplifier, I thought, since it was more powerful, put on really powerful music that will take advantage of it like the Conan soundtrack.
I put in the Bryston, cranked it up and…huh? Where was that power? Why did it actually sound thinner? Less impactful?
The Bryan did have better grip from the upper bass on down - it unravelled some of the in their power range down there, that were a little bit more muddy on my CJ amps. And it was perhaps a tiny bit cleaner on the horns when playing their loudest.
But otherwise , it just sounded actually weaker and thinner, and it didn’t have the punch and drama I was used to.
I put this down to the type of distortions from the CJ amp - less damping factor probably allowed for a little bit rounder sound in the power region. And that little bit of tube distortion over the whole thing, thickening out the sound. Essentially, I think the tube was acting something like a mild bit of compression, at least in Sonic analogy terms.
The Bryston did better on some other stuff. But most often the CJs sounded richard and fuller, and I often liked even the bass better. It was a little bit more round and had more feel, without being slowed down or losing any pace or snap.
So anyway, every time I do this comparison, I go running back to my CJs. Which is why I’ve had them for like 25 years. |
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