The circuit is very forgiving... It will generally sound the same with 100V or 300V save to overload conditions like a skip.
How would you use 8 double triodes in an RIAA stage? Unless all of them are 20 mu AND you were using a lot of degeneration, or some of them maybe not amplifying….. Are you using tubes for CCS’s and the B+ voltage reg too? I’d turn it off if it wasn’t being used too - it almost seems like a separate piece of equipment.
I’m planning a “preamp“ build too - and was thinking about not powering unused sections. Heaters and B+ off when not in use. Multiple input mixer. Two balanced low Z line drivers and switchable high/low pass at 80/120 Hz per channel - for multiple applications. Its going to be my “tube Driverack”. Power requirements for the output stages aren‘t trivial there either. All together 26 bottles, most with a triode and pentode in them. Probably mechanical relays for heaters (AC) and MJE350’s in the B+’s.
What?
You must have mitakenly read my comment.
There are no tubes powered on my console until I turn it on.
Yes, four of them are used as CCS loads. Think Aikido without the mojo...
But you do power the phono all the time while using the console? Whether or not you're listening to records? Most systems do - My old Belcor does, too but it only uses two 12AX7 so not nearly as wasteful.
The added-in "custom" RIAA stage is SS, because the system originally used an RCA changer with ceramic cartridge.
The Garrard 3000 has a Pickering MM cartridge.
I'm not overly concerned with electrical useage, however I naturally turn things off when not in use, and often-used lamps have LED bulbs in them now.
But worrying about tube "wastefulness" is kind of obsessive behavior.
My system runs 24/7. It's not really obsessive to cut out almost 1kW/h a day IMHO 🙂 Not to mention a set of tubes for the phono stage can cost more than 100$...
In your case, with that 8 tube preamp, yes, it's worth it to shut it down when not in use.
Some of us, me included, do not deal with that class D stuff.
It's A/B or occasionally A.
Class D is fine for some things (subwoofer amp comes to mind) but I wouldn't use a class D amplifier for RIAA duty. I do have a class D amp that's about 5 watts that I use when they plan an electric shutdown to listen to music from battery though. It sounds remarkably good for a 10$ POS.
The only solid state amp I've built uses more electric than my tube amps... It's single ended and loaded with 300 watt light bulbs and the front end is tubes...
The only solid state amp I've built uses more electric than my tube amps... It's single ended and loaded with 300 watt light bulbs and the front end is tubes...
I guess I'll spend the rest of the week wondering how you could conceptually make a class-D phono preamplifier and whether that has any advantages. Just a class-D output stage embedded in an otherwise conventional phono preamplifier wouldn't have any clear advantages, but maybe you could think of some switched-mode voltage multiplying stage to noise-match an MC cartridge to the amplifier input, as an alternative to a step-up transformer? It sounds unnecessarily complicated, though, and it isn't really class-D, although it is switched mode.
I'd make the "class D" phono amp like:
Cartridge -> AD converter -> gain/riaa curve by DSP -> class D output or USB...
Cartridge -> AD converter -> gain/riaa curve by DSP -> class D output or USB...
I am glad you caught on to that! My comment was in jest, but going digital with a delta sigma from the get go might be a realistic possibility. Won’t be a tube phono preamp though!
This before I switched to LEDs, I didn't even need to use heat in the winter.
Now I'm using LEDs and a 1500W heater cycles 10% to 30% of the time during the coldest months. I used it today in fact. Two days ago, it was 28°C in here and I considered switching over to A/C which is 12000 BTU in 380 sqft... Facing south, living at the top of the building, stack effect, and terrible circulation unless it's windy outside is fun... especially when you use tubes 24/7 🙂
Now I'm using LEDs and a 1500W heater cycles 10% to 30% of the time during the coldest months. I used it today in fact. Two days ago, it was 28°C in here and I considered switching over to A/C which is 12000 BTU in 380 sqft... Facing south, living at the top of the building, stack effect, and terrible circulation unless it's windy outside is fun... especially when you use tubes 24/7 🙂
What surprised me more was the combination of class D and a preamplifier. I never associated those with each other until Potentiallyincorrect mentioned class D in this thread about phono preamplifiers.