Can tube amps give true high end bass?

"How can a 40wt tube amp give better bass than Krell 450 mono's"

Perhaps its how you define 'bass', perhaps its a personal preference for a 'fuller' sound as opposed to a 'tighter' sound. Perhaps its just plain electrical synergy with your speakers.

I have noticed over the years that in gereral there seems to a correllation between equipment which produces 'tight bass' and produced thinner, more ascerbic mids and highs, which can be described as airy or bright depending on you preferences for one or the other. I've always suspected, apart from plain old synergy, it was due to the way that rise and decay times were treated in the amp - that is the methodology used to get tight bass was as much due to a shortening of the decay time of a signal as anything else and the warmth of tubes was due to a less sharp rise time.

I'm still looking for a tube or ss amp which has the best of both designs, that has warm, full, tight low frequencies with natural mids and highs allowing for great detail with no thinning or brightness. I used to feel like Diogenes til one day the wind blew out the lamp. :-)

There are several problems that most transistor designs face in order to play bass.

The first is, perhaps a bit counter-intuitively, that they are direct-coupled. Direct coupled amplifiers have response to DC, but when you think about it, the power supplies don't. *They* have response to some very low frequency, perhaps 1/10 cycle/second, but unless run by batteries, not full on DC. Especially at power, the result is that the amplifier can modulate the power supply rails. This results in weakened bass.

A frequency pole in the amplifier (coupling cap for example) that sets the amplifier -3db point *above* the power supply pole will alleviate that problem.

The second issue is negative feedback. Most transistor amplifiers are not very linear without it and so employ a fair amount to work. At low frequencies negative feedback in addition to reducing distortion also seem to compress dynamic impact.

The result: big transistor amps that cannot play bass. Sure, they have 'punch' as the feedback has left them unable to create low frequency definition. So what you will hear in a tube amp that is built right is: Impact, bass definition, and a subtle thing that is always the first to go when things go wrong: bass ambience.

Enjoy!

If your tube amps compliment the impedence characteristics of your speakers, there is no reason that tube amps can't produce the control needed on the woofers. The problems start when the tube amps aren't properly mated to the right speakers and get overdriven, saturate the transformer and generally let the woofers run wild.

Radical phase angles, substantially wild impdence curves and inefficient speakers give tube gear fits. You gotta match this stuff up right. When it's right, it's very right.

Newbee, have you looked at the Atma-Sphere amps? You're comment:

"I'm still looking for a tube or ss amp which has the best of both designs, that has warm, full, tight low frequencies with natural mids and highs allowing for great detail with no thinning or brightness."

is exactly what I found in the Atma-Sphere MA1's. I was completely stunned by the bass articulation they provided to my Magnepan MG3.6r's, a speaker that most say can NOT be driven by a medium powered tube amp, much less an OTL. It truly was a revelation! The mids were gorgeous and the highs as airy as I've ever heard...really made me appreciate the Maggy ribbon tweeter, something I wasn't fully able to do when they were powered by my Parasound JC1 monoblocks.

Ulf, I do think good tube amps can provide better bass. Six or seven years ago I used Manley Neo Classic 250 tube amps with Avalon Eclipse speakers and I found the bass more natural than with my previous Levinson SS amp.

I spent several years living in Soulard (St. Louis area) and listened to live music at least 4 times per week. The Atma-Sphere's, and to a lesser extent the Manley's driving the Eclipse, provided a much more realistic upright bass. The way an upright bass projects out into the room is not a start/stop affair...it's hard for me to describe it...maybe "expansive". You get the initial transient followed by this ballooning of the fundamental and it's harmonics. Oh heck...my language is horrible...wish I could describe it better.

Good luck!
Jordan