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Vintage threads from the first ten years

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Re: 5F6A pics & build tales

6/29/2005 2:10 AM
Simon	Re: 5F6A pics & build tales Please can you answer a couple of questions for me . I am in the middle of building a 5F8a based amp and looked at your photo's with interest ..nice job . However one thing that interested me was that you appear to have used switching jacks on the input . I have assumed going by the schematic that the jacks are normal type , have I cocked up already or did you use these jacks ignoring the third tag ? I am actually only using two inputs on mine and have planned to base the front end more Marshall like with separate 820ohm / 220uf + 2.7k / .68uf cathodes . I want to be able to bridge both inputs via a rear mounted switch working off the tube socket rather than the input end ( shorter wires) Now here's the question : Do I need to keep both 1M grid ( on jacks to ground) resisters in the circuit when both inputs are bridged or will one 1M handle both sides of the pre-amp tube . The theory was that if you keep both 1M's in the circuit they are effectivly in parallel= 500k to ground and some valuable input signal could be lost . Sorry , bit of a long one ..

6/29/2005 2:10 AM

Simon

Re: 5F6A pics & build tales

Please can you answer a couple of questions for me . I am in the middle of building a 5F8a based amp and looked at your photo's with interest ..nice job .
However one thing that interested me was that you appear to have used switching jacks on the input . I have assumed going by the schematic that the jacks are normal type , have I cocked up already or did you use these jacks ignoring the third tag ?
I am actually only using two inputs on mine and have planned to base the front end more Marshall like with separate 820ohm / 220uf + 2.7k / .68uf cathodes . I want to be able to bridge both inputs via a rear mounted switch working off the tube socket rather than the input end ( shorter wires)
Now here's the question : Do I need to keep both 1M grid ( on jacks to ground) resisters in the circuit when both inputs are bridged or will one 1M handle both sides of the pre-amp tube . The theory was that if you keep both 1M's in the circuit they are effectivly in parallel= 500k to ground and some valuable input signal could be lost . Sorry , bit of a long one ..