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8.2 K resistor JTM 45 Build
Posted: Fri Mar 25, 2016 3:08 pm
by dan_tramble
Hello all
Don't mean to ask a stupid question however building another 45. The 8.2 k 2w resistor between the 27k NFB resistor and 10uF bias cap. According to the schematic it connects the B+ off the 16uF filter and runs across the board and then carries on to the other end of the choke lead and to the other B+ side of the dual 32 uF filter.
I am missing a 8.2k resistor from valve storm. The closest I have is a 10k. Reads 9.6 k on my Fluke 115
Can I use that as a substitute?
Please advise
Happy Easter everyone!!!
Best regards
Dan
Re: 8.2 K resistor JTM 45 Build
Posted: Fri Mar 25, 2016 3:37 pm
by shakti
Yes you can, at least as long as it's rated at least 1W. 2W is safer.
Re: 8.2 K resistor JTM 45 Build
Posted: Fri Mar 25, 2016 3:53 pm
by dan_tramble
What kind of effect will that have on the circuit? Will it change the tone any in your opinion?
It looks as though it is just a resistor in the filtering section of the amp
I figured I could use it because most parts in the good
Old days were +- 20% up to. 10k is 20% off of 8.2k
I am in Canada and I tried my local electrical supplies store and they don't have that particular resistor in stock
Getting it online would mean a long wait
I have 10k 2 watt resistors here (leftovers from other valve storm
Kits).
Thanks and please advise
Regards
Dan
Re: 8.2 K resistor JTM 45 Build
Posted: Fri Mar 25, 2016 5:05 pm
by shakti
You will not be able to hear the difference. It will drop the voltage to the preamp a *tiny* bit more than the 8.2k, but as you say, tolerances alone could account for about the same differences. Same thing with wall voltage variations, which would probably lead to as big or even bigger changes in the working voltages inside the amp. You can safely use it for now, and if, for historical accuracy, you should want to change it later then you can do that.
Re: 8.2 K resistor JTM 45 Build
Posted: Fri Mar 25, 2016 6:05 pm
by dan_tramble
shakti wrote:You will not be able to hear the difference. It will drop the voltage to the preamp a *tiny* bit more than the 8.2k, but as you say, tolerances alone could account for about the same differences. Same thing with wall voltage variations, which would probably lead to as big or even bigger changes in the working voltages inside the amp. You can safely use it for now, and if, for historical accuracy, you should want to change it later then you can do that.
Thank you for your help and advice
Best regards
Dan