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

Tonecat · Post by **Tonecat** » Fri Nov 10, 2006 12:48 am

Hey Larry. I finished my PPIMV mod about a week ago with your help. Thank You!! However, I mounted mine in the presence pot hole in the front and used shielded cable. I dont seem to be having any problems with it. I did run the shielded cable back to the board using the bias feed for the shield ground and then the board wires to the tubes. How much improvement could I expect if I ran twisted wires from the pot directly to the tubes and didn't use shielded cable or should I just leave it alone?

tonejones · Post by **tonejones** » Fri Nov 10, 2006 1:16 am

Is there any 2m in the metro store (I can't find 'em if so)??????

The 250k pot, it's not a dual???

rockstah · Post by **rockstah** » Fri Nov 10, 2006 1:23 am

tonejones wrote:Is there any 2m in the metro store (I can't find 'em if so)??????

The 250k pot, it's not a dual???

alpha dual 250k lin pot

tonejones · Post by **tonejones** » Fri Nov 10, 2006 1:31 am

Thanks Rockstah....

You & Larry's da man!!!!!!

5150loveeddie · Post by **5150loveeddie** » Fri Nov 10, 2006 1:55 am

rockstah wrote:
5150loveeddie wrote:Ok you get the flowers AND the Chocolate.....
haha! that sounded bad didnt it? well the things we try to type sometimes come out funny in text.

Yeah I have the same problem Larry has, I always have to think in English not in french so I make mistakes alot,,,,duh!!!

rockstah · Post by **rockstah** » Fri Nov 10, 2006 2:35 am

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!

novosibir · Post by **novosibir** » Fri Nov 10, 2006 8:27 am

rockstah wrote:but i did use 2m and 220k in series u say i could use just the 2m. kewlness!

I've suggested the 2.2M, because it's an everywhere easy to get value.

But in fact you can use every value between 1.5M and 2.2M as the 'safety resistor' on the pot. The 'resulting resistance' with the pot dimed is only varying between 214K and 224K

But anyway the 250K pot only seldom has a value of exactly 250K - the 250K Mouser's i.e. are differing by my experience between 223K and 264K - so you may decide, if the pot's value has plus tolerance, then choose the resistor's value lower (i.e. 1.5M or 1.8M), and vice versa.

So don't worry too much about the concrete resistor's value!
That really doesn't make any difference in sound or reliability!

Larry

novosibir · Post by **novosibir** » Fri Nov 10, 2006 8:34 am

Tonecat wrote:Hey Larry. I finished my PPIMV mod about a week ago with your help. Thank You!! However, I mounted mine in the presence pot hole in the front and used shielded cable. I dont seem to be having any problems with it. I did run the shielded cable back to the board using the bias feed for the shield ground and then the board wires to the tubes. How much improvement could I expect if I ran twisted wires from the pot directly to the tubes and didn't use shielded cable or should I just leave it alone?

From the presence's position to the output tubes it's a much longer way, than from an speaker jack's hole to the tubes. So I'd at least keep the shielded wires from the pot's wipers to the tubes.

And remember another rule!

Never touch a running system!

Larry

rockstah · Post by **rockstah** » Fri Nov 10, 2006 8:37 am

novosibir wrote:
rockstah wrote:but i did use 2m and 220k in series u say i could use just the 2m. kewlness!
I've suggested the 2.2M, because it's an everywhere easy to get value.

But in fact you can use every value between 1.5M and 2.2M as the 'safety resistor' on the pot. The 'resulting resistance' with the pot dimed is only varying between 214K and 224K

But anyway the 250K pot only seldom has a value of exactly 250K - the 250K Mouser's i.e. are differing by my experience between 223K and 264K - so you may decide, if the pot's value has plus tolerance, then choose the resistor's value lower (i.e. 1.5M or 1.8M), and vice versa.

So don't worry too much about the concrete resistor's value!
That really doesn't make any difference in sound or reliability!

Larry

good to know - man i love this place. i am addicted.

rockstah · Post by **rockstah** » Fri Nov 10, 2006 8:39 am

novosibir wrote:
Tonecat wrote:Hey Larry. I finished my PPIMV mod about a week ago with your help. Thank You!! However, I mounted mine in the presence pot hole in the front and used shielded cable. I dont seem to be having any problems with it. I did run the shielded cable back to the board using the bias feed for the shield ground and then the board wires to the tubes. How much improvement could I expect if I ran twisted wires from the pot directly to the tubes and didn't use shielded cable or should I just leave it alone?
From the presence's position to the output tubes it's a much longer way, than from an speaker jack's hole to the tubes. So I'd at least keep the shielded wires from the pot's wipers to the tubes.

And remember another rule!

Never touch a running system!

Larry

that would be the next thing to try - no shielding to the tubes indeed!

rockstah · Post by **rockstah** » Fri Nov 10, 2006 9:00 am

Larry,

i do believe everyone is waiting for your approval on the above layout i drew up.

it is how my amp is currently wired up with this master volume.

Mark

rockstah · Post by **rockstah** » Fri Nov 10, 2006 9:25 am

here is another file - it was the first take - same settings on the amp - i decided to post it cause it does give more insight of the tone of the amp with this master volume... it also gives more insight on how little i have been playing due to my addition for smelling solder.

http://www.soundclick.com/bands/songInf ... ID=4649398

please forgive my poor chops on these takes... but hey!...listen to that voice! the tone is there!

Mark

Brentsp · Post by **Brentsp** » Fri Nov 10, 2006 10:51 am

I just added the PPIV (500k) and used 470k resistors. For whatever reason I like this better than when I had it with 220k bias resistors.

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

Brentsp wrote:I just added the PPIV (500k) and used 470k resistors. For whatever reason I like this better than when I had it with 220k bias resistors.

try this PPIMV.

rockstah · Post by **rockstah** » Fri Nov 10, 2006 10:53 am

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!