ST-35 up and running in New Hampshire/ Why no input caps?

[EWBrown]

The input caps are not needed in most cases, as long as the audio source (preamp, CD player, tuner, etc) doesn't have any DC on its output.
All coupling caps add some "color" or "flavor" to the audio signal, so one less cap means a slight amount less affecting of the signal.

The difference are very subtle, I know my ears aren't sufficiently "golden" to tell the difference, YMMV.

/ed brown in NH

[EWBrown]

In my systems, I use linestages or preamps that I haved either designed and built myself, or ones that I have repaired and modified (like Dynaco PAS3, etc). This way I know that their audio outputs do not carry DC. If I am in doubt, I'll throw in a DC blocking cap just to be safe. This applies to CD players, especially. Someday, I'll replace the output section of my CD player with a simple tube linestage, I've been told this can make a very noticeable improvement. There is enough empty space inside to add this and a lot more.

The actual percieved sonic differences that an extra cap in the signal path may make, are subtle at most, and probably indiscernable to most.

I am not gifted with "golden" ears, and most of my equipment is true vintage, even the main speakers in my system are 1960s vintaegt Bozak
B302As, top of the line back then, but probably far short of the better offerings available today. I just like the sound that the total system produces. I also have a pair of vintage AR2As which need woork, the tweeter and midrange pots have gone bad, and I have a pair of AR4s with blown woofers, that were free for the taking.

Those willl eventually get re-stuffed with new drivers. Any other speakers I have are just considered "test" speakers, most of these are smaller shelf units and won't win any SPL efficiency contests

One thing that all these "vintage" speakers have in common, is that their higher frequency response ijust sn't as "crystalline" and clear as that from more modern tweeters and supertweeters. They might not be "muddy" sounding (except for the ARs) , but then they don't have that undescribable sensation that newer units have.

My "listening room" is currently my cellar, which more resembles an electronics and junk surplus warehouse, than an actual music studio Yellow_Light_Colorz_PDT_05 so what passes for "acoustics" is pretty poor at best. I figure if a setup down there sounds good, then it should really shine in a good listening environment.

/ed b in nh

[Shannon Parks]

In my experience I've found out about dc offset being present in preamps and sources (going into direct coupled amps) only when it was too late. That's why I'm a bit paranoid about the issue of blocking caps.

Hi 4chords,

Very good observations, 4chords. I made the decision to drop the DC blocking caps in the Rev D for a one reason - there isn't a low voltage value, cheap, small package, easily accessible 'DIY audiophile grade' DC blocker out there.

From the engineering aspect, I wanted to use a 50V polyester cap (small, cheap and does the job). I felt this was the best solution, but would turn off many people. If the product was for the consumer market, I would have designed DC blockers in. But some folks were already subbing the polyprop Xicon I had in there and it might cause folks to spend an extra $20.

I ultimately I came down on the DIY side of it all and yanked them. A leaded polyprop (or polyester) can easily be connected directly to the RCA input (then to the PCB) for those wishing DC protection. I'll document this in the revised manual.

I may try to Spice some scenarios with the ST35 frontend and various DC offsets.

Shannon