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

gnugear · Post by **gnugear** » Sat Mar 18, 2006 9:23 am

wilder wrote:Here's a pic of a a 1973 PCB installation:

Chris

Do you have a pic of the ground wire? I'm doing it to my '73 as well but I blew a fuse. I think the way I connected it might be wrong. It's so much easier on a ptp!

Billy Batz · Post by **Billy Batz** » Sat Mar 18, 2006 10:08 am

Theres no wire going to the chassis ground you know. The two left terminals of the pots go to the bias before the feed resistors

McGoogle McDougal · Post by **McGoogle McDougal** » Sun Mar 19, 2006 7:06 pm

I'm thinking of putting one of George's PPIV master volume kits in my Bluesbreaker. I know some of you guys said you don't like the sound of these, but I'm wondering if you still have objections when it's only used to reduce the volume a little?

I think anything sounds kind of fizzy at bedroom volume (master volumes or attenuators), but I would assume that if the master is up all the way it is essentially out of the circuit. For the most part the amp I have no trouble turning the amp up as loud as I want (sometimes it's not even loud enough), but occasionally I have need to just knock it down a little. I use a fuzz face for drive with my strat, but it sounds too brittle if the amp is not breaking up a little and I thought a PPIV master would do the trick in those situations.

Thoughts, opinions?

Eamon

jngreene79 · Post by **jngreene79** » Mon Mar 20, 2006 5:39 pm

I was in the same situation that you're in. Needed it down just a bit... I did it to a JTM 45 and it sounded pretty good - no too fizzly. As was mentioned in the thread earlier, the wiring 'dress' might have something to do with the fizzles. I use a 120pf snubber cap across the PI anyway. This may have helped fizzles, but I doubt it would make a drastic, audible difference. I'm pretty sure that Mark 'Rockstah' prefers the PPMV, and everything I've heard from him sounds pretty damned good. I recently did it to a 2203 and I liked it more than on my amp. If you built the amp, then it's a piece of cake to try it. I still PREFER a little attenuation instead. -James

Necrovore · Post by **Necrovore** » Mon Mar 20, 2006 7:12 pm

I'm a bit confused in regards to using shielded wire in this mod. I have shielded cable here that has one wire core inside a larger covering that has foil "shield" snadwiched between the inner wire covering and the outer covering. Do I just cut the wire enough so that I use the inner wire and thats it or would it be a good idea to pull off some of the foil and solder only one end of that to the pot back?

I have done this mod before but used just normal hookup wire and got the fizzies on the top of the notes played.

Bainzy · Post by **Bainzy** » Tue Apr 04, 2006 1:59 pm

You could try tightly twisting the wires that go to the 220k resistors together, and then doing the same with the 2 wires that go to the coupling caps. That would cancel out extraneous noise.

MacGaden · Post by **MacGaden** » Mon May 01, 2006 3:58 pm

sam wrote:
joe G wrote:I'd REALLY like to see pics of this done to a PCB 1959 or 1987!

PPIMV with cascaded inputs

cheers

sam

rockstah · Post by **rockstah** » Mon May 01, 2006 4:20 pm

until someone trys it we just wont know - try using 4 individual shielded cables for you PPI master volume.
we dont want any of those wires talking to eachother.

bmf5150 · Post by **bmf5150** » Wed May 03, 2006 10:52 pm

i have my pot in one of the input jacks.using sheilded wire to keep nise down,seems to work good!

Kuli · Post by **Kuli** » Thu Jun 08, 2006 5:43 am

Hi guys!

Will one of these pots do the job?

http://elektronik-lavpris.dk/eshop/show ... O_ID=95602

I know it's a 470K pot and the recommended pot is a 500K. What effect will a 470K have compared to a 500K?

rockstah · Post by **rockstah** » Thu Jun 08, 2006 11:56 am

Kuli wrote:Hi guys!

Will one of these pots do the job?

http://elektronik-lavpris.dk/eshop/show ... O_ID=95602

I know it's a 470K pot and the recommended pot is a 500K. What effect will a 470K have compared to a 500K?

it will be 30k away from 500k. when your volume is up full it will have 470k resistence. 30k away from away from being on 10 so to speak.

MacGaden · Post by **MacGaden** » Thu Jun 08, 2006 1:55 pm

Also these pots are very poor quality. Not the kind you

rockstah · Post by **rockstah** » Thu Jun 08, 2006 2:04 pm

PEC pots all the way

Kuli · Post by **Kuli** » Thu Jun 08, 2006 4:49 pm

Hi MacGaden & rockstah.

Thank you, I will order some good ones then.. (Those I found was very cheap so there had to be some kind of catch to them..)

MacGaden:
No problem! I'm looking forward to hear from you again!

Kuli.

SDM · Post by **SDM** » Thu Jun 08, 2006 5:27 pm

rockstah wrote:
Kuli wrote:Hi guys!

Will one of these pots do the job?

http://elektronik-lavpris.dk/eshop/show ... O_ID=95602

I know it's a 470K pot and the recommended pot is a 500K. What effect will a 470K have compared to a 500K?
it will be 30k away from 500k. when your volume is up full it will have 470k resistence. 30k away from away from being on 10 so to speak.

When you slap 500K's acrossed your 220K bias feed resistors as in a very popular version of the PPIMV your drop their value to 152.8K when the pot is cranked. With a 470K dual pot they drop to about 149.8K, only 3K difference. Either leaves you 70K short of 220K at least.

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

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