300b lovers

@lynn_olson

"However ... the way the Raven is configured now, it can only drive one output at a time, either XLR or RCA. Well, technically it can drive both at once ... no harm is done to the circuit or any parts ... but the load is then unbalanced, with more cable capacitance on one side than the other. So the amp with the balanced inputs will receive a signal that doesn’t quite match at high frequencies."

I wonder if this is an issue since the XLR’s are just driving the bass, however this happens with in the internal crossover in the speaker. I spoke with Don on the phone today, getting clarification from Legacy how this works with RCA and XLR together in bi-amp.

Lynn makes note of hearing Purifi Class D amps at the show in a favorable way.   I did hear Atma-Sphere's new GaN mono amps driving the the Tekton Moabs and I thought they sounded excellent.  I could easily see a synergy between the Raven and Ralph's mono amps and I personally would require a tube preamp with any amp I might choose to use.  That Ralph has made such a move to Class D technology after decades of being a tube designer/manufacturer ought to make the audio community sit up and take notice.  What I heard of his $5500 amps was very impressive.  Of course, let your ears be the judge.

I am luxuriating with Don's DS2 preamp and his new 300b monos driving my now run-in Cube Audio Jazzon speakers.   I am enjoying the sound in my room to a degree that I have never experienced before.  From morning to night...   

The Raven is particularly well-suited to driving transistor amps because:

1) The transformers prohibit the transmission of DC pulses to RCA and XLR outputs, under all conditions, including total failure.

2) Unlike solid-state preamps, there are no DC servos to fail. There are no coupling caps on the output to store turn-on pulses, unlike cathode-follower designs. No muting relays are needed, or used, so the signal path is direct from transformer secondary to output.

3) All internal circuitry is fully balanced. The faint click when the VR tubes light up is only due to small residual imbalance (no more than 2%) in the 6SN7’s. Balanced operation alone reduces noise by 30 to 35 dB, then the VR tubes another 20 dB, and then 130 dB from the regulated power supply.

4) In addition to internal balanced operation, phase splitting at the input and output is entirely passive, not using discrete transistors, op-amp inverters, or split-load tube inverters. The custom transformers are precision balanced through 30 kHz, ensuring accurate phase balance for the power amplifier, whether it is solid-state or vacuum tube.

5) The input connections are floating, breaking any potential ground loops from the DAC or phono preamp. The transformers only respond to differences between signal pairs, with 80 dB or better common-mode noise rejection. The transformers also reject radio-frequency interference (RFI), passing only audio-band signals.

My personal award show notes from PAF, including the room with the amp in this thread:

*Most intensely rich yet detailed tubey midrange: LTA prototype DAC,  LTA Pre, LTA Ultralinear+ monoblocks, and Daedalus Argos V3 speakers

*Most delicate and intricately revealing top end with too much mid-bass: VAC components and Von Schweikert Ultra 7 speakers

*Second place for best top end and also clear midrange but garbled bass: Songer + Whammerdyne

*Most gossamer presentation: Don Sachs' Raven/Blackbird + Spatial Audio Lab X series speakers

*Largest sounding very small, yet full range speakers: Gershman

*Most humongously oversized images and stage and most impressive driver tech: Aavik/Ansus and Borreson M6

*Most resonant enclosures: Black Ocean Audio

*Most disappointing tonality: Joseph Audio Pearl Graphene speakers

*Biggest surprise: Vanatoo's little office stereo sized powered speakers

*Friendliest exhibitor reps: Tie between Furutech and ASC

*Most advantaged by vibration control: Millercarbon

*Most classic solid state sounding room: Infigo Audio

*Most inoffensive yet not all that unique sounding room: Bella Sound

I wish I had heard the Dutch & Dutch 8C’s. The exact opposite approach of our room, but 100% valid: internally tri-amped with DSP for the side-firing drivers to create a near-perfect cardioid radiation pattern. Digital-in is limited to 48/24 PCM (higher-rez content is accepted but internally downsampled), and the triple internal amps are Class D with 400W each. I was reading Amir’s ASR show report (third section) and the Dutch & Dutch exhibitor was measuring 15 Hz during setup.

This might be anathema for some readers, but I like the massive engineering effort that must have gone into this bookshelf speaker. DSP to shape the polar response with side-firing drivers is not trivial, and from the reviews, they actually tamed the hotel rooms that were driving the rest of us nuts. Of course, with DSP tailored for each driver, the speaker would be flat as a pancake, not a bad thing.

For analog fans, the prospect of converting every precious LP on-the-fly to plain old 48/24 PCM is appalling, and for high-end DAC fans, the standard-issue ESS or AKM converters hidden inside the Dutch & Dutch are probably not acceptable. So you pick the approach that you like.

Surprisingly, Amir, of all people, liked both Spatial rooms. Did not expect that. The real invective on ASR was reserved for the absurd cables in the ballrooms ... to be honest, have to agree there. The Anticables we were using worked just fine, and were unobtrusive, as a cable should be.