Crimson 350 and Raven 350 bring added clarity, life and presence to
any loudspeakers.

A long time ago, Bob Carver settled on three words that embodied his design philosophy:  Powerful.  Musical.  Accurate.  Three companies and 40+ years later, Bob has brought the same three values firmly into the 21st century…in the form of the Crimson 350 and Raven 350 tube power amplifiers.  

Crimson and Raven invigorate your music with extended dynamic range and abundant power reserves that can ignite explosive excitement. Yet they can also paint subtle shades of naturally warm, timbral color that are completely free from tube glare.


To car-jack a metaphor, Bob has effectively combined the raging muscle of an 800 horsepower turbocharged diesel 4 x 4 with the cool agility (and mirror finish) of a Lamborghini Veneno Roadster.

What’s the difference between the Raven 350 and the Crimson 350? Their chassis color. Choose from a hand-rubbed ebony finish so deep you can practically dive into it, or a hand-rubbed crimson finish so smolderingly red that your cat will want to sleep next to it on chilly evenings. Aside from that, the amplifiers are sonically identical. Note that the Raven finish, rarely ordered, is special order only at no cost but they are hand-built to order. Please be patient!

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Firing on all six cylinders. Well, actually tubes.

Crimson and Raven use six Tung-Sol KT120 beam pentode output tubes, each capable of 60 watts of audio output. Introduced in 1950, this design evolved from an up-rated industrial version of the 6L6 and has found a home in everything from ’59 Fender Bassman amps to B-52 Bombers. For connoisseurs of dense tech jargon, we are proud to add that the KT120 has an oxide-coated, indirectly-heated unipotential cathode, too.

One hundred and fifty percent more powerful than the ubiquitous 6550 or KT88, the Tung-Sol KT120s sound, according to Bob… ”beautiful, sweet and so incredibly delicate that it is hard to believe.  While I like their unique shape, the only drawback to them is that the plate structure hides their beautiful warm filament glow in a darkened room.

Staying tuned-up.

To further belabor automotive metaphors, tubes need tuning up. 
Or rather they need their bias adjusted, which is akin to setting engine idle speed. Traditionally, amplifier tubes have been operated at a very high bias (rather like idling an engine at high RPMs) in order to keep distortion low and frequency response extended. High bias drastically shortens tube life — in fact tubes begin to deteriorate as soon as the amp is turned on.

The 6AL5 DC Restorer, exclusive to Bob’s designs, changes all that.  It keeps the KT120s running cool, prolonging their life beyond 50 years — and eliminating the need for expensive matched tube sets. Screen voltage is regulated on speech and music to an almost impossible to achieve 1%; distortion is reduced three-fold, the bias regulator perfectly restores the DC component of the incoming signal.

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Heart and soul:  the output transformer.


Continuing the automotive metaphors…if six KT120 tubes in push-pull configuration are the Raven/Crimson’s engine, its transmission is the massive, hand-wound output transformer.

The Raven/Crimson transformer design is derived from a combination of Bob’s famous Silver Seven transformer and Stu Hegeman’s classic Citation II, but with thicker wire and larger core. It contributes significantly to the amp’s hefty 44-pound weight. And dramatically to overall performance.

This brute delivers enormous power through an increased turns ratio, with two extra interleaved windings, each bifilar wound on a core of adamantine steel with a pure nickel center section. The transformer secondaries are wound with oxygen-free copper wire for critical internal interconnections. Power bandwidth is 24 Hz to 45 kHz; frequency response from 2 Hz to 85 kHz!

The extra-wide bandwidth ensures perfect stability into one-ohm speakers, including those that possess almost impossible-to-drive impedance characteristics! Even the one-ohm Apogee Scintillas, or any other speaker that dips down to 0.75 ohms, for that matter. This amplifier can drive them all with aplomb!

Why choose Bob’s design?


Our lengthy text has mostly stayed on the objective, tangible aspects of the Crimson/Raven design. (and you can read even more about Bob's ingenious design in the three links below. )

Subjective sound quality is an intangible that you will ultimately have to sort out by yourself.  With your favorite music. In your own home.

However, we can present the comments of satisfied owners: 
They report authoritative, controlled bass; radiant midrange with smoothly decaying transients, and top-end sparkle.  Visit our site’s Accolades page for a sampling of these.


Continuously coherent and capable of stunning dynamic range, the Crimson and Raven sound wonderfully warm, yet not at the expense of resolution of detail.


We’d like to build you a pair.

Want to learn more?

Read about yet even still more cool Crimson/Raven features.

Classic or Contemporary Feedback? Flick the switch

It "listens" along with where you’re playing it.

The benefits of
point-to-point wiring