I am sure this was discussed before at length, but I cannot seem to find any link, so I apologize if this is the second edition.

I wonder how different rectifier tubes affect the tone of an amp, i.e., what is the mechanism?  At the end of the day, the rectifier is not in the audio signal chain, right?  Different rectifiers might be providing different voltage levels, but if two separate ones measure exactly the same, what spec causes the tonal difference?

Even though I have a B.Sc. in engineering, it is in the field of industrial engineering, so I might need an explanation at the “dummies” level!  :)

I have my degrees in Economics and Statistics, and received a D+ in Digital Logic Design in undergrad before figuring out Engineering was not for me...

... but my ears work fine and there's a clear difference in sound with different Recitifers, especially Rectifiers of different types. Not idea what internally is causing that, but I find the difference to be substantial.

I have had these things pretty steadily on my minds for quite a while. And doing amp modifications through this time I think I may have gotten a better sense of how it all interrelates....So I have a lot to say, but hopefully useful for getting closer to sorting these rectifier questions out.


In 2016, encouraged by Vyokyong's work on the Mystery amp, I started going inside the amps. Modifications have been based on sound rather than tech, but I have learned some tech to help me understand parts and materials a little better toward getting the sound I want. So this conceptual overview may be weak on the tech side, but I hope not too much. And hopefully these experiments, based on how things work individually and together, with sound as the primary criteria, might help toward conceptualizing how our amps work, and why rectifiers have clear sound differences.

My 1st experiments with my Torii and CSP3 were attenuators, coupling caps, and power supply bypasses. The attenuator, being in the signal path proper, it was quite obvious how the quality of attenuator design and parts effected the sound.

Also, different coupling caps, as part of the signal path, made sense being so influential to the sound. But it did not take many power supply bypass experiments to become clear that these bypasses were pretty much as influential sound-wise as coupling caps!

First I thought this made some sense because good quality low value bypass caps would speed up and clarify the slower, less extended electrolytic caps. But soon I noticed each bypass cap “sound” was pretty much as you would expect that cap to sound whether in the power supply or "signal" path. Baffling at first, I think it may be beginning to make a little more sense.

Broadly speaking, I guess that input transformers, chokes, rectifiers, power supply caps, and associated wires, literally create the qualities of the power for the signal path tubes and circuits. And each power supply part imparts its particular ways of making and carrying energy, so each part’s sonic character has direct influence on the sound.  

Along with design, how well power supply parts are made, and how good the materials are for the intended use, it seems to me that the filtering and energy from the power supply can be quite variable. And thinking the power supply works to support everything, including output transformers, and that this energy is used to amplify the signal....beginning mixing with the signal path energy in the signal tube stages, it seems to me that it becomes part of the signal. Doesn't the energy from the power supply/rectifier, and the signal energy, join together in the signal tubes, powering up, and creating new beginnings for the signal. And if so, couldn’t we extrapolate that the power supply is part of the signal path, and therefore power supply parts can reveal their sonic qualities like those in the signal path?



More specifically looking at parts sound, we know different wires and dielectrics effect the energy they carry differently, some much better than others in terms of allowing a more pure transmission....Like solid core Ultra Pure Ohno Cast Continuous (UP OCC) silver in teflon, combining the purest silver with the longest crystal structure, the wire has the highest transmission potential with the least barriers to energy flow structurally.… and teflon, having a stable and low dielectric constant, it is good insulation, while having less damaging effect on the energy the wire carries than many wire coverings. Combined, this conceptually provides an avenue for some of the least adulterated energy transmission we can realistically get in amps. And in my tests, it does more fully convey all of the nuances of sound, retaining fragile micro detail and harmonic complexity with natural smoothness, when many wires can truncate these qualities. So whether in the signal path proper, or for power, you can hear UP-OCC silver, clear, smooth, extended, a little warm.

Compared to say OFC stranded copper, a conductor with more impurities and flaws in the wire draw, and stranded, more energy crossing wire strand connections, there appear to be many more "distractions" for the energy. And though it can sound good, in comparison, you can hear that it is not as pure as UP-OCC solid silver, generally less revealing and smooth…. more veiled and edgy.

Illustrating how different materials and making methods can create audible differences, similar differences can clearly show in transformers, chokes, caps and tubes that make up the power supply. So materials and designs used can seriously influence the energetic qualities of the power, and therefore the signal, including the rectifier.

And likewise with all tubes, the particular design, wires, materials, production methods....individually and collectively they influence the sound of a given tube..... Presumably, in earlier years, those NOS tubes we tend to love, the weighting of economic versus quality seemed to have had a different balance for design and production parameters. Many made for important things like planes, jets and communication, durability and quality were critical to reliability and performance. Supporting this, seems they used more virgin metals, wire, glass, etc, as well as using the best making techniques. So tubes tended to be better at what they do.....and we can hear that too. Having been made with care and integrity out of need, production-wise and material wise, 50-80 or so years later we get to enjoy really good sound from them today. And since they are all a little different in design, construction, materials, wires, glass quality and weight, etc, tubes with the same electronic parameters sound different, giving us loads of choices.



But back to power supplies. A few years ago I had changed the Torii electrolytic caps to Jenson 40 uF from Illinois Capacitor 47 uF. My hope was for a more complex cap sound from using electrolytic caps made specifically for audio, and using less value, hoping for a little less weighting toward bass. Though changing cap types made it hard to gauge accurately, this did appear to work, the bass tending to less thick, and the sound from the electrolytic caps more complex and complete. But I wondered if at high volumes, the lower cap value was contributing to earlier rectifier sag, and to minor dips into distortion at a little lower volumes. The sound was amazing, with everything present, and a beautiful soundstage, but I wanted a touch less saturated feeling at volume, and hopefully a little more volume before distortion on hot notes.

I had been meaning to try a pair of Clarity TC 45 uF film caps in the CSP3 power supply, thinking the film might be more extended, less smeared, and faster. But a tight fit, recently I decided to try them in the Torii replacing the 1st position electrolytic cap, a cap that is associated with the input transformer, choke, and rectifier. I hoped this would improve the rectifiers by raising the value and quality of the rectifier filter cap. And being film, I hoped for less soft/slow, with more clarity, and without adding too much weight to the bass even though the value was 5 uF more. I think this more-or-less worked...creating more clarity, complex detail, and spatial complexity, while probably carrying the sound at the highest volumes a little better....it so far sounds better with a little more input gain from pre stages, but became more musical.

The cleaner and more powerful rectifier filter cap also made different rectifier sonic characters more clear and richer than they had been, the combination taking the whole of the amp to a new level of resolution, while becoming even more musically complex and captivating.

And incidentally, this pretty big cap cleared up almost all remaining transformer hum. A little more noise removed, this is bound to have improved the signal. Finally, the same rectifiers were made more complete and clear in showing their own character, and transformer noise improved, the cap change making the whole amp notably better. This seems to verify that how well the rectifier is supported in creating the power for the signal path, has a big influence on the signal tubes, and therefore the signal path.



Through all my experiments, whether “power supply,” or “signal path,” with a variety of connectors, wires, resistors, caps, attenuators...all were pretty obvious to the sound. And changing a cap, resistor or wire in either revealed more-or-less predictable results based on the sonic traits of the parts used beyond their electronic parameters. No matter where or when...from the input signal RCA connectors and the IEC power connector, all the way through everything leading to the output binding posts, it all sounded like signal path to me.

So I wonder…..Since the power and the signal merge at the signal circuits, and in the signal tubes, isn't the energy from the power supply just as important to the sound as the energy of the signal path? And taken a little step further, aren't our Decware power supplies functionally part of the signal path? And finally, depending on how a rectifier is designed and made, the rectifier being a fundamental contributor to the signal, wouldn't rectifier sound be clearly heard beyond measured voltage and amperage? My thoughts today anyway….

Looking forward to thoughts, any corrections and ideas!

Will

Thanks Lon. Nice!

I agree, beauty and harmony in life and music are meaningful goals and can be transformational. To me also, there is nothing that is not important toward these ends.

Related, when I feel best in the world, it is easier to tune my sound, and when my system is sounding compelling, alive and balanced, I feel more alive and balanced.

Rectifier choices are no doubt every bit as important in this as any of the others, and likewise VRs, both effecting all the other tubes and everything else in big ways. It is sort of magical to me how amazing it can be to play with good amps and tubes to bring systems out fully in a given setting!

I think rectifiers sound different in tandem with the electricity provided them (it's quality and nature) and I think we underestimate the influence of the differing structures of each rectifier type and build and also the materials that they are designed with and made from. I think that is where the majority of tonal and textural differences may originate.

So the power supply does matter and slight differences are distinguishable via the treatment they give the tubes.

I recently ran a comparison of about seven different pairs of rectifiers in both my main system and my audio visual system--all five components in those systems can use the same rectifiers. It was NOT subtle the differences each rectifier exhibited. Even the same type with a bit of difference from another manufacturer clearly stood out. Fascinating. . . maddening if you have a "seeking" nature and keep flitting from one complement to another!

I'm now driving myself a little crazy in my main system listening by rolling voltage regulator tubes for the output tubes. Each type and brand standing out saying "Hear me! Hear me!" in their own voice.