ANY relation AT ALL with OP question? (8k and 4k resistors as tube plate load in case everybody forgot)
😕 🙄 😱
DIY Audio never ceases to amaze me. 🙄
No, don´t tell me "discussion just drifted there", absolutely unrelated answers to not asked questions were pulled out of the blue.
I worked at Ferranti Transformer Division in the testing lab at Toronto while I still had hair, during internship. The equipment made possible 2 MV for testing insulators & a 330 KV AC supply for insulation tests on core & coils. Also a 240 Hz alternator driven by a 75 HP synchronous motor used for double voltage tests. Because the power factor of core & copper tests results in a very low PFs, there has to be isolation between the supplying utility & the load. A very large motor/generator provides that function. In this case the motor was a 1300 HP synchronous type driving an alternator with many taps on the stator. That way many different sized transformers could be tested. There were two complete systems of this type. I recall timing the rotor after shutdown, it took 45 minutes to stop. No brakes.😱
The driving motor starts as an induction motor & just below synchronous locks into the line supply as a synchronous motor. Skin effect in the copper bars on the rotor is sometimes used to start these machines. But not this pair.
Both oil cooled & air cooled transformers were built. Glass & Porcelain insulation was used for the air cooled. But most were oil cooled, some by oil & a few by PCBs, now banned. It is a heavy liquid, quite noticeable when picking up a pail of it!
Had two fires along the way, one in a large circuit breaker on a continuous run test. The other on the steel bands left on the core during a core loss test.
These transformers were physically very large 3-phase things, shipped on railway flat cars.
Nuff said.🙂
ANY relation AT ALL with OP question? (8k and 4k resistors as tube plate load in case everybody forgot)
😕 🙄 😱
I thought the OP's question was well covered at the beginning of the thread, the first few posts. Others may differ.🙂
😕 🙄 😱
I thought the OP's question was well covered at the beginning of the thread, the first few posts. Others may differ.🙂
I agree with you jhstewart9: answers have been given, who priginally asked is happy with the off opic replies, no need to post twice just to flame saying the we all went off topic.
Cheers!
Cheers!
i have replaced 12k with a 10k for plate load resistor and got away with it....no biggie...
ever wondered why tube amps in the past used 10% or higher resistors?
ever wondered why tube amps in the past used 10% or higher resistors?
Tolerance of parts used in anything is determined by requirements to meet the spec followed closely by the selling cost / bottom line. So consumer grade amplifiers will perform OK with 10 % tolerance parts & keep the cost down.
Check the tolerance spec on an electrolytic cap, might be -20% / +100%.
Check the tolerance spec on an electrolytic cap, might be -20% / +100%.
Just dial the current up/down a bit until you maximize the ac voltage (or minimize the distortion) with the plate resistor value that you happen to have. I do keep more values of the lower R lower wattage resistors you’re more likely to use in the cathode circuit.
My guess is both of you are old enough where you could still *get* 20% resistors. Even 10% were on their way out when I started buying from Radio Shack. Most of use are “old farts” by the usual definition (when you don’t care for the music the kids are listening to).
There are probably still some 20% resistors in my stash but I wouldn't be using them now. The first electronics I built were simple regen receivers. A buddies father was a projectionist in a movie theater, so a couple of WE 264s followed me home. The filaments on those things ate #6 cells. Later another regen a lot easier on the filament supply, a SW receiver based on a 1H5GT detector & a 1N5GT audio amp. It drove a set of 2K headphones. It easily received European stations including Radio Moscow & many Spanish stations in Central America.
The first audio amp was a PP 6U6GT effort. The PS was a half-wave doubler based on selenium rectifiers right off the line, real dangerous.😱 The heaters were on a 6V Hammond transformer.Then many more based on 6V6s, 6K6s, 6L6s & on & on. They probably had both 10 & 20 percent resistors but all worked.
As always, the transducers are the most difficult part of any sound system. Definitely spend a lot of money on that before anything else. These daze good performance from amplifiers both SS & toobz are not a problem at all.
More snow on the ground this AM. The driveway is about 450 feet, I'll be on the tractor for a while.🙂
The first audio amp was a PP 6U6GT effort. The PS was a half-wave doubler based on selenium rectifiers right off the line, real dangerous.😱 The heaters were on a 6V Hammond transformer.Then many more based on 6V6s, 6K6s, 6L6s & on & on. They probably had both 10 & 20 percent resistors but all worked.
As always, the transducers are the most difficult part of any sound system. Definitely spend a lot of money on that before anything else. These daze good performance from amplifiers both SS & toobz are not a problem at all.
More snow on the ground this AM. The driveway is about 450 feet, I'll be on the tractor for a while.🙂