Studio Preamp Mod confusion

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Bottle Rocket
Posts: 12
Joined: Mon May 26, 2014 7:55 pm

Studio Preamp Mod confusion

Post by stav92 » Sat Aug 29, 2015 4:07 pm

Hey guys, basically I took my Studio preamp to my tech to have the 2c+, Bass shift and pull deep mods and he performed them for me.

However, he was reluctant to change the input grid 1M resistor to 680k as he says this lowers the input impedance of the preamp. I asked him to follow the mod sheet and swap the 1M for 680k anyway.


I'm wondering now if the 680k input resistor on the Bass shift mod is a mistake ... Pretty much every amp has a 1M resistor at the input, so I can't understand why somebody thought changing it to 680k as all it does is mess up the impedance...

Would the drop from 1M to 680k have caused any change in tone/high-end content/signal strength/gain ??

Does anybody know whether this is a mistake ?? Should I change it back to 1M or just stick with the 680k now its already soldered in??

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Re: Studio Preamp Mod confusion

Post by JMMP » Sun Aug 30, 2015 3:38 pm

I probably would not have changed it to the 680K, however now that it is changed, I wouldn't change it unless you feel it is affecting your tone in a negative way. In this case, I think the only difference will be a little less hot of a signal going into the preamp, but if you're using active pickups, very hot passives, or a buffer of any sort, there may not be that discernable of a difference between the two input impedances.
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