300b lovers

These are the kind of conversations I used to have with Harvey Rosenberg, who definitely "got it". Unless you knew him, you didn’t realize his clowning around, and occasional jaunts into speculative metaphysics, was an act designed to chase away mainstream audiophiles (which it did). Of course, I can speculate about metaphysics for hours on end, as folks who met me at the PAF discovered. But the clown act was pure Harvey ... I’m too sobersided to joke around like that. But we did discuss the subtler aspects of musical perception, and how they interacted with culture and worldview.

I am not sure where capacitor coloration comes from, or what’s causing the hours-long "burn-in" process. It can’t be measured, and the plausible mechanisms are pure guesswork. But it’s there. In a positive sense, direct-heated triodes, in the right circuit, have very special qualities.

Not everything is revealed by the spectrum analyzer, and the usual audiophile lingo falls short of describing what triodes really sound like. Sanskrit or Japanese might be better, but I don’t speak either, although I am conversant with a few basic Zen, Taoist, or Vedanta concepts. English is not particularly good at discussing subtle aspects of perception and consciousness.

Now that Don has built a version with zero coupling caps, he’s having the same experience I had when I first heard the Amity in 1996. The Karna was a development of that, and the Blackbird is a development of the Karna.

Basically what Lynn just said.  Once you hear it you cannot go back.  Even the best caps cannot touch it.  Now, that said, you will not hear this if the rest of your system is not up to the task.  You put a $500 DAC in front and a mediocre preamp that uses small signal tubes, and a mediocre pair of speakers behind and you will mask all of this.  You are not going to get this with cheapo ITs either.   The Lundahls I played around with last year sounded good, but rang at 15KHz.  That doesn't mean Lundahls are bad, just that they were not designed specifically for this circuit.  So if you get really good quality ITs that are designed for your circuit, then you will hear what Lynn described.  These replaced VCap ODAM, and I also tried top shelf Miflex and Duelund JDM copper foils.  All are very good caps.  None has the realism of the custom wound Cinemag transformer.  I have no doubt the Monolith iron is superb and I am about to try their OPTs whenever they arrive.   But you need iron of this quality.  You wouldn't judge all coupling caps based on a cheapo Solen, nor would you judge all ITs based on something like a Hammond or Edcor.

There are levels and to my ear in our circuit (important caveats), the top quality IT is better than the top quality coupling cap used in the LC with a very good anode choke.   My 2 cents and feel free to disagree, but it is what I hear.

What you will hear in your circuit .... I don't know, and it doesn't make me right and you wrong or vice versa.

Agree 100%. Don is describing what I hear.

The metaphysics are optional, but they have a good toolkit for describing perception.

See page 21 for a construction article on a push-pull, zero-feedback 300A/300B amplifier. This is about the same time as Columbia introduced the LP microgroove record, so it’s very early days for high fidelity. What surprises me about this article is that 300A’s and 300B’s were even for sale to the public; they must have been pulling them out of prewar theater equipment

At the time of printing, the only records you could actually buy were 78’s, and FM radio was very new. Note the primitive state of tonearms and phono cartridges ... also, 78’s had no standard equalization, so preamps had to cover several curves, including "acoustical" for pre-electronic records.

The reign of the monophonic LP record was surprisingly short; ten years later, almost to the month, stereo LP’s were announced by all the major labels, and stereo cartridges and stereo preamps were also on the market.

Audio magazine, July 1948

Audio magazine, August 1958, the Stereo Issue

Audio magazine, November 1982, first CD player

What is the minimal inductance is acceptable for 6sn7 interstage transformer ? 80H, 70H, 60H?

The problem is transformers with high inductance have narrow high frequency bandwidth. But if interstage transformer doesn't have high enough inductance with 6sn7 the low frequency will be cut off.