Promethium cap 1u5 uncommon

[paulbarrette]

The promethium calls for 1u5 elec in c16. 1u5 is uncommon. Nextgen (local) guitars sells 0.47u caps. There is a postal strike on here so my options are limited. I can put a 0.47u in parallel or just go with a 1u cap.
Thoughts?

Pb

 

[Nostradoomus]

Use a .47 and 1uf in parallel, it does not sound right without the proper values in the tone stack at all

 

[paulbarrette]

Use a .47 and 1uf in parallel, it does not sound right without the proper values in the tone stack at all

Thanks. I suspected that section was sensitive.

Pb

 

[Chuck D. Bones]

C16 is part of a series-resonant tuned circuit. The center freq is proportional to the square-root of C16's value. That means a 20% change in C16's value moves the center freq by 10%. The resonant freq of the C16 circuit is 87Hz, assuming C13, C16, R21 & R25 tolerances are zero.

C16 is an aluminum electrolytic cap. The typical tolerance on Al electro caps is ±20%. They almost always end up on the high side of the tolerance band. I would expect the majority of 1.5μF Al electros to be around 1.7μF. That puts the resonant freq at 81Hz. A 2.2μF cap would move the resonant freq down to 72Hz. Tantalum and film caps have a tolerance of ±10% or better.

Bottom line, you could use a 1.5μF Al electro, 1μF & 470nF in parallel or 2.2μF tant and they would all sound pretty much the same. Any differences would only be evident if LOW is at zero or 10.

Just had my morning coffee, so I'm feeling rather verbose.

 

[paulbarrette]

C16 is part of a series-resonant tuned circuit. The center freq is proportional to the square-root of C16's value. That means a 20% change in C16's value moves the center freq by 10%. The resonant freq of the C16 circuit is 87Hz, assuming C13, C16, R21 & R25 tolerances are zero.

C16 is an aluminum electrolytic cap. The typical tolerance on Al electro caps is ±20%. They almost always end up on the high side of the tolerance band. I would expect the majority of 1.5μF Al electros to be around 1.7μF. That puts the resonant freq at 81Hz. A 2.2μF cap would move the resonant freq down to 72Hz. Tantalum and film caps have a tolerance of ±10% or better.

Bottom line, you could use a 1.5μF Al electro, 1μF & 470nF in parallel or 2.2μF tant and they would all sound pretty much the same. Any differences would only be evident if LOW is at zero or 10.

Just had my morning coffee, so I'm feeling rather verbose.

Thanks for the detailed explanation! My plan is to use 1uf + .47uf in parallel. Looking forward to the chain saw

Pb