The PPIMV (Post-PI-Master-Volume) thread.

rtcook · Post by **rtcook** » Fri Nov 10, 2006 10:55 am

Just a thought on the resistor choice...

All the pots I've ever measured have always come up short of their advertised value. So, wouldn't that be a factor here too? If the 250K pot only actually measures 230K that means you would need a 5M resistor. Please correct me if I'm wrong or if this accuracy is really not necessary.

Thanks,

Roger

rtcook · Post by **rtcook** » Fri Nov 10, 2006 10:59 am

Brentsp,

Actually 430K resistors are a better choice to get closer to the original 220K. But, with this new PPIMV with the 250K pot is looking to be a much better choice.

Killer tone Mark! I wish I could play half as good as you.

Roger

rockstah · Post by **rockstah** » Fri Nov 10, 2006 10:59 am

rtcook wrote:Just a thought on the resistor choice...

All the pots I've ever measured have always come up short of their advertised value. So, wouldn't that be a factor here too? If the 250K pot only actually measures 230K that means you would need a 5M resistor. Please correct me if I'm wrong or if this accuracy is really not necessary.

Thanks,

Roger

i did measure mine and it was suprisingly 250k - with the 2.220m resitor config i ended up with 223k with the pot dimed.

but yeah you could search and get it to be exactly 220k with teh added resistors but again its doubtful those 220k resistors on the board are exactly 220k before the master install. so i figured close enough.

rockstah · Post by **rockstah** » Fri Nov 10, 2006 11:07 am

rtcook wrote:Brentsp,

Actually 430K resistors are a better choice to get closer to the original 220K. But, with this new PPIMV with the 250K pot is looking to be a much better choice.

Killer tone Mark! I wish I could play half as good as you.

Roger

too kind man.

rtcook · Post by **rtcook** » Fri Nov 10, 2006 11:35 am

Mark,

I only call it like I hear it!

Thanks Larry and Mark for all the effort you put into this PPIMV. We all appreciate it. Funny George hasn't said a thing yet?

I guess when I get my 250K pot I will just measure it and calculate the proper resistor. I agree with you Mark that the original 220K's may have been off in the first place. So, close enough is good, but I'm gonna check anyway. Seems as though the higher you go with a pot the further it is off. So, the 250K should be alot closer than the 500K.

Roger

Brentsp · Post by **Brentsp** » Fri Nov 10, 2006 11:44 am

rtcook wrote:Brentsp,

Actually 430K resistors are a better choice to get closer to the original 220K. But, with this new PPIMV with the 250K pot is looking to be a much better choice.

Killer tone Mark! I wish I could play half as good as you.

Roger

yeah would be but I don't have any 430ks. Anyway when the pot is cranked up the PI measures 228k......so obviously the 500k are measuring lower.

rtcook · Post by **rtcook** » Fri Nov 10, 2006 1:01 pm

Yes, all the 500K pots I have measured have come up short. The Alpha's more then the PEC's.

Roger

rockstah · Post by **rockstah** » Fri Nov 10, 2006 3:07 pm

rtcook wrote:Yes, all the 500K pots I have measured have come up short. The Alpha's more then the PEC's.

Roger

i used a 2m resistor and a 220k resistor in series on my dual 250k lin pot-the pot ends up being around 223k when dimed.

rockstah · Post by **rockstah** » Fri Nov 10, 2006 3:44 pm

rockstah wrote:i know all you guys are probably going back and forth trying to figure out how this mod is done EXACTLY!

try this.

the pics of it in my amp.

the sound file
i thought i should post this PPIMV clip. recorded late last night.

using the post phase inverter master type 2 - using a dual 250klin pot -
sylvania long plates in the pres and jj e34l's outputs.
Strat with a darkburst with an A2 magnet in the bridge and a dimarzio vintage 54 in the neck

this was recorded at 2am - everything dimed - master at 1 - (bedroom level.)

please excuse the performance on it. i have been sniffing alot of solder lately.

http://www.soundclick.com/bands/songInf ... ID=4647605

Mark

p.s. a special thanks to Larry!

Larry, they need your stamp of approval on the diagram here.

pongo316 · Post by **pongo316** » Fri Nov 10, 2006 4:26 pm

Mark Whats your thoughts on this vesion compared to the previous ones used ???

rockstah · Post by **rockstah** » Fri Nov 10, 2006 4:45 pm

pongo316 wrote:Mark Whats your thoughts on this vesion compared to the previous ones used ???

did u hear the clip? this one blows away the other one tried. hands down. end of story.

novosibir · Post by **novosibir** » Fri Nov 10, 2006 4:47 pm

rockstah wrote:Larry, they need your stamp of approval on the diagram here.

A P P R O V A L . . G I V E N ! ! !

The schematic, Mark has draws is absolutely correct! And I'm glad, that Mark did it, because I still didn't try to work with a design program for schematics and layouts. I'm an 'old school' tech - and all my schematics and layouts (a couple of hundreds meanwhile

) still are hand drawn.

To give you all still some clearing words:

Don't worry too much about the resulting resistance with the pot dimed and the safety resistors soldered to - all values between 200K and 225K ARE GOOD and don't influence the sound in no way!

But OTOH the 'safety resistor' should not be bigger than 2.2M, so that it can do its 'job' properly in event of a possible pot's wiper failure.

Larry

rockstah · Post by **rockstah** » Fri Nov 10, 2006 4:49 pm

novosibir wrote:
rockstah wrote:Larry, they need your stamp of approval on the diagram here.
A P P R O V A L . . G I V E N ! ! !

The schematic, Mark has draws is absolutely correct! And I'm glad, that Mark did it, because I still didn't try to work with a design program for schematics and layouts. I'm an 'old school' tech - and all my schematics and layouts (a couple of hundreds meanwhile ) still are hand drawn.

To give you all still some clearing words:

Don't worry too much about the resulting resistance with the pot dimed and the safety resistors soldered to - all values between 200K and 225K ARE GOOD and don't influence the sound in no way!

But OTOH the 'safety resistor' should not be bigger than 2.2M, so that it can do its 'job' properly in event of a possible pot's wiper failure.

Larry

thank you Larry! have at it peoples u wont be disapointed with thsi PPIMV

*clears throat* WHAT? i used a 2meg and 220k in series for 2.220M resistor on the pot - to big?

novosibir · Post by **novosibir** » Fri Nov 10, 2006 4:51 pm

rockstah wrote:*clears throat* WHAT? i used a 2meg and 220k in series for 2.220M resistor on the pot - to big?

No!

Is there any difference between 2.2M and 2.22M

rockstah · Post by **rockstah** » Fri Nov 10, 2006 4:52 pm

novosibir wrote:
rockstah wrote:*clears throat* WHAT? i used a 2meg and 220k in series for 2.220M resistor on the pot - to big?
No!

Is there any difference between 2.2M and 2.22M

yes 20k?