Peavey cap id.

[Colas LeGrippa]

Hi, I just can't understand the capacitor value indicated in the schem.  of a Peavey classic 30, at the guitar input. It says: .1 R250MY.  If 250 means 250V, why it is so big ? What means R, and MY ?


Thanks

[sluckey]

Hi, I just can't understand the capacitor value indicated in the schem.  of a Peavey classic 30, at the guitar input. It says: .1 R250MY.  If 250 means 250V, why it is so big ? What means R, and MY ?

According to the parts list for the C30 it's a .1MFD 250VDC Mylar cap. That's all I need to know.

[Colas LeGrippa]

...of course MY stands for Mylar !!!!  Is there a risk that 250V develops on the grid ? Is it the reason why my guitar pot is scratchy sometimes, and sometimes not ?

[PRR]

Going lower voltage would not save much money. Mylar naturally comes several hundred Volts thick. Thinner Mylar, you need less pounds, but it costs more per pound to make it thin and handle it without ripping. And they may have had a 0.1u 250V cap already in the parts bins. (Peavey's designers were "strongly encouraged" to use parts already in the system, not invent new part-needs for Peavey to source, test, and inventory.)

[Colas LeGrippa]

Ok I see.  Why mylar and not polyprop ?

[sluckey]

Ok I see.  Why mylar and not polyprop ?

That same cap is used in many different Peavey amps. It's solely responsible for that signature "Peavey" sound that Lynyrd Skynyrd made so famous in the '70s.

[Colas LeGrippa]

sweet home Alabama tone ...