lynn_olson
Responses from lynn_olson
| 300b lovers A quick note on the complex variable equalization seen on the Citation I: people who had extensive 78 and pre-1955 LP collections had records with wildly varying equalization curves. By the time of the stereo LP in 1958, the world had settled on t... | |
| 300b lovers Before getting lost in the weeds on balanced vs single-ended phono preamp design, it might be useful to review the general types and look at their advantages and disadvantages. 1) The most common is a high-gain stage with RIAA frequency-shaping f... | |
| 300b lovers Very pretty! Which driver tube? | |
| 300b lovers Just to confirm, the Raven and Blackbird do NOT use the Acrosound circuit shown above. The signal path is considerably simpler. | |
| 300b lovers Acrosound UL-II schematic. Note the input 12AX7 is direct-coupled to the 12AU7 driver stage, so DC drift from internal 12AX7 mismatch could be a problem. Technical analysis: The input signal goes to the top half of the 12AX7. The bottom half is c... | |
| 300b lovers If all these transformers disgust you, or you want to use local or global feedback, you can re-visit the Acrosound schematic from the late Fifties. Three stages, all differential, each RC-coupled to the next. It can be easily updated with modern c... | |
| 300b lovers In essence, the signal flow is: Complementary Pair of 6SN7 sections -> Signal is re-summed in the transformer -> Complementary Pair of triode-connected KT88 drivers -> Signal is re-summed in the transformer -> Complementary Pair of 300... | |
| 300b lovers Ralph brings up a very good point about feedback: the underlying theory assumes a distortionless summing point. (The summing point is the comparator input between signal input and the sampled output.) Any distortion introduced at this point of the... | |
| 300b lovers Yes, it’s difficult to get people to understand that Class A push-pull is quite a different animal than the much more common Class AB push-pull. I understand the reasons for Class AB ... it’s much more efficient, but Class A working is not the sam... | |
| 300b lovers Wow, is that the first Atma-Sphere with an output transformer? Sounds like the 300B amp is well on track, and I imagine the next version will have current sources in the appropriate positions. I’m curious what your experience with a high-power cu... | |
| 300b lovers Ralph, I see you introduced a PP 300B amplifier at one of the recent hifi shows. How do you think it compares to your Class D amplifier, in subjective terms? Since you designed both, you're the best qualified to assess the differences. | |
| 300b lovers One of the nice things about working with Cinemag is their custom design service. This gets us away from the many limitations of standard off-the-shelf transformers from other vendors. We specify source impedance, the range of loads (including cap... | |
| 300b lovers Of course, it is tempting to design a special-purpose headphone amp. I own HifiMan HE1000 Stealth (V3) planar headphones myself, and I use a modest all-in-one DAC/headphone amp to power them. But ... the headphone amp market is quite crowded, and... | |
| 300b lovers In terms of load abuse, plugging planar headphones (20 ohm to 32 ohms) into the Raven preamp will definitely load down the preamp and is not recommended. No harm will result, but the preamp will slide over into Class AB operation and distortion wi... | |
| 300b lovers The Raven is not very sensitive to loads. In practice, power amps range from 10K (typical solid-state) to as high as 470K for a handful of vintage tube amps. Most modern tube amps are 100K. Plus whatever cable capacitance is there, along with the ... |