Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Colas LeGrippa on April 02, 2018, 09:14:23 am

Title: Peavey cap id.
Post by: Colas LeGrippa on April 02, 2018, 09:14:23 am

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



Title: Re: Peavey cap id.
Post by: sluckey on April 02, 2018, 09:37:07 am

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. :wink:
Title: Re: Peavey cap id.
Post by: Colas LeGrippa on April 02, 2018, 10:30:02 am

...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 ?

Title: Re: Peavey cap id.
Post by: PRR on April 02, 2018, 10:44:51 am
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.)
Title: Re: Peavey cap id.
Post by: Colas LeGrippa on April 02, 2018, 11:03:59 am
Ok I see.  Why mylar and not polyprop ?
Title: Re: Peavey cap id.
Post by: sluckey on April 02, 2018, 11:39:22 am
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.
Title: Re: Peavey cap id.
Post by: Colas LeGrippa on April 02, 2018, 12:50:41 pm
sweet home Alabama tone ...