It's those diffracted lines around the pin. Presuming your other 12AU7 is good? just take a look to compare.
However, gotta ask... how it it get like this? Kid throw something across the room and hit the tube?
it looks the same to me. i have no idea. is it that rare for something like this to occur?
its only been put on and removed a handful of times since i purchased. it was sold as 'nos' rca blackplate ... maybe its just old?
I retract what I say about the cracks because I realized it could just be the way the light is refracting in the photos. However I do think that you should replace it.
My fav 12AU7 is the GE ones that are labeled Hammond - the organ manufacturer. My least favorite are the “clear tops” everyone raves about.
I considered it too but decided against it… Those are double the heater current… You’d be stressing out the little bridge rectifier and possibly the 0.47 ohm resistor in the H+ supply…
on the bright side, these are cheap and plentiful parts of you do burn them out but I cannot comment on other collateral damage since that supply also feeds the auto bias reference.
Just want to confirm that anything other than a 12au7 (0.3A heater) will in likely send the H+ supply into thermal protection.
Tried a 12BH7 (0.6A heater, as it turns out) but went the sound cut out after about 15 minutes, biggest clue was the LED went dim, which uses the H+ supply.
I did the reckless experiment so nobody else has to
Tried a 12BH7 (0.6A heater, as it turns out) but went the sound cut out after about 15 minutes, biggest clue was the LED went dim, which uses the H+ supply.
I did the reckless experiment so nobody else has to
If you had asked how you could use preamp tubes with 0.6A heater current, you would not have had to do potentially harmful experiments.
Hi, I ordered the 8200R from Japan and received the 8200 instructions and not the 8200R instructions. I soldered about 20 resistors in until I noticed that it was not the right set of instructions. I have contacted the distributor and Elekit and have received no response in over a month. I see 8200 and 8300R instructions online but no 8200R. Can someone point me towards a cops of the 8200R instructions (in English!). Thanks.
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Hope that helps
vkung, its concerning that elekit does not seem to reply to those who need the right instruction manual. But i guess you are able to supply JDM49 the right instructions and the 115/230 board he need.