8.2 K resistor JTM 45 Build

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dan_tramble
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8.2 K resistor JTM 45 Build

Post by dan_tramble » Fri Mar 25, 2016 3:08 pm

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
MetroAmp addict!
JTM 50/45,1987's & 1986
1959 and 2203/2204 Amps
1974 amp

Can't stop building, very addictive!

shakti
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Location: Ramnes, Norway

Re: 8.2 K resistor JTM 45 Build

Post by shakti » Fri Mar 25, 2016 3:37 pm

Yes you can, at least as long as it's rated at least 1W. 2W is safer.
JTM45 RS OT, 1973 18W, JTM45/100, JTM50, JMP50 1986, JMP100 "West Coast", AC15, AC30, BF Super Reverb, Boogie Mk 1, Hiwatt CP103, DR103

dan_tramble
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Posts: 37
Joined: Fri Dec 19, 2014 11:34 am
Just the numbers in order: 13492

Re: 8.2 K resistor JTM 45 Build

Post by dan_tramble » Fri Mar 25, 2016 3:53 pm

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
MetroAmp addict!
JTM 50/45,1987's & 1986
1959 and 2203/2204 Amps
1974 amp

Can't stop building, very addictive!

shakti
Senior Member
Posts: 2053
Joined: Tue Apr 05, 2005 9:06 am
Just the numbers in order: 7
Location: Ramnes, Norway

Re: 8.2 K resistor JTM 45 Build

Post by shakti » Fri Mar 25, 2016 5:05 pm

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.
JTM45 RS OT, 1973 18W, JTM45/100, JTM50, JMP50 1986, JMP100 "West Coast", AC15, AC30, BF Super Reverb, Boogie Mk 1, Hiwatt CP103, DR103

dan_tramble
New Member
Posts: 37
Joined: Fri Dec 19, 2014 11:34 am
Just the numbers in order: 13492

Re: 8.2 K resistor JTM 45 Build

Post by dan_tramble » Fri Mar 25, 2016 6:05 pm

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
MetroAmp addict!
JTM 50/45,1987's & 1986
1959 and 2203/2204 Amps
1974 amp

Can't stop building, very addictive!

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