Come back when it has a valve rectifier. Solid state diodes in my interconnects? No. Oh no. No no no no no....
That experiment was a rather crude prototype of a single ended triode amp that made about 200 watts. It was put together to test a prototype OPT that I had custom made, and powered by a supply I ripped out of a decommissioned UHF radio transmitter which was rated for 1500 volts at 500 mA. One Zaaapp from that thing could kill you and cook your corpse rather quickly. The proto existed for about a week about 15 years ago. When I figured out that it wasn't good enough for HiFi, I played my guitar through it for a few days, then dismantled it all. Except when I took a few pictures there was a 1/4 inch thick sheet of Lexan between me and it.
Not just any vice-grips, but a specially selected pair with just the right coating of Florida brown iron oxide to help disperse the evil parasitics. The hose clamps used for the plate and grid pins were selected from several that had been removed from the car I was dismantling in the yard. These were a matched pair from the heater core.
The most common antenna for these tubes is indeed the secondary winding of a vacuum tube Tesla coil. I had 12 good tubes, but sold most of them to a guy was building a BIG Tesla coil. There were plans floating around the web at the time for a really big Tesla coil that used 6 of these tubes.
Also called "active guard". Buffer the center wire signal and drive the shield with it. Bingo! Capacitance is gone! Just like that.
erm don't you need Triax for that to work. If you drive the shield with the signal with coax your signal has gone as well!
There still needs to be a method for connecting the two common / ground sides of the two units together.
The concept is to drive the shield with a low impedance signal of equal amplitude and phase of the center conductor signal to reduce or eliminate loss in the cable. Triax with the outer layer being used for the ground is the best way that I know to do this.
In my opinion it is better to design the source with a near zero output impedance so that within reason, cables don't matter. I design and build all my own stuff, but that's not an option for those who don't.
It's also not an option for things like turntables....unless you build the phono stage into the turntable base right at the two pair coming out of the tone arm.
The concept is to drive the shield with a low impedance signal of equal amplitude and phase of the center conductor signal to reduce or eliminate loss in the cable. Triax with the outer layer being used for the ground is the best way that I know to do this.
In my opinion it is better to design the source with a near zero output impedance so that within reason, cables don't matter. I design and build all my own stuff, but that's not an option for those who don't.
It's also not an option for things like turntables....unless you build the phono stage into the turntable base right at the two pair coming out of the tone arm.
I might be called Tubelab, but this is one place where a pair of LME49720 opamps and a handful of other SMD parts are the right parts for the job. I made mine back when I could get the chips for free from the National Semiconductor Sales rep.
Some solder, bare wire, heat shrink and a whole lot of patience can make it work in XLR connectors.
We also had some triaxial connectors at Motorola that were screwed together and looked somewhat like an Type N connector that was about 40 years ago and I have no idea what they were called. I can find pictures of triaxial BNC connectors on the Pasternack web site, but I can't actually figure out what they connect to, or how to buy them.
We also had some triaxial connectors at Motorola that were screwed together and looked somewhat like an Type N connector that was about 40 years ago and I have no idea what they were called. I can find pictures of triaxial BNC connectors on the Pasternack web site, but I can't actually figure out what they connect to, or how to buy them.
The ones I'm used to are kinda like big compressed air fittings, They have the standard for broadcast TV cameras for years.
Canare L-4CFTX Video Triax Camera Cable (328''') CATRIAXFM328 B&H
Canare L-4CFTX Video Triax Camera Cable (328''') CATRIAXFM328 B&H
As to point A, if you do that “all cables sound the same” - at least that’s the idea. How close you come to that goal depends on a lot of things. When you get the electronics to be insensitive (enough) to cables, that’s one less thing to be fretting over or spending time or money on. You can then spend it on things that matter more and won’t eventually get your thread locked. Cable wars always do.
Moving magnet (or coil) cartridges, on the other hand, are usually tuned to want a specific load - usually 47k and some *non zero* amount of capacitance. Some DIY preamps have provision for tuning the load capacitance. Maybe some ridiculously priced high end stuff does too but your typical receiver does not. It will be just designed with some assumption about the cable. If it’s right, or in the ballpark, frequency response will be as advertised. If it’s far off, it won’t be. If you build in the preamp and put exactly the 200 pF or whatever the cartridge wants right at the tone arm, then the cable to the amp won’t matter as much. Then you’ll be swapping out cartridges, because they behave slightly differently into a fixed capacitance.
I love the high end tips I get here! I'm going to build a Wheatstone bridge and match up some of my curated collection of used hose clamps. Superb!
On the real tip, that benchtop amplifier looks scary. I never did anything like that in my tube days. I always prototyped and tested right in the chassis.
"In complex words, the sound is indescribably incredible." . This must be the content free line of words of the century ;-)
Jan
Jan
One cat running through the middle of it would cure that. The wife might never let you play with tubes again.
It's something I have never understood. The average tonearm cable is 100-150pF before you even start and yet MM stages rarely take that into account. Thank $DEITY for DIY and the ability to have total control over this (within limits set by SWMBO)
150 pf sounds a little high for the unshielded twisted pair in a tonearm. Your typical garbage grade RCA cord is about 30 pF/ft.