Author Topic: Need help with GGG phase 45  (Read 1488 times)

handlefras

Need help with GGG phase 45
« on: November 25, 2007, 02:13:23 AM »
I have built the generalguitargadgets phase 45 replica on a pcb but cannot get any phase effect, only a clean sound. I have used all parts from the BOM apart from the 1N5230 diode (which I replaced with another 4.7V zener) and a 100k linear pot instead of 500k reverse log taper. I am not certain on the orientation/pinout of the transistors. I used the 2N5952 JFETs (matched with the Geofex matcher at 1.655 and 1.658Vgsoff) and it appears that the flat should be rotated 180 degrees from the diagram. I have tried many different orientations so if someone could confirm the GGG diagram for me? it would be much appreciated. Has anyone made this circuit? Also if anyone has any other ideas…


http://www.generalguitargadgets.com/index.php?option=com_content&task=view&id=156&Itemid=26


Here are my readings:

IC1
1: 3.03
2: 3.03
3: 2.89
4: 0
5: 3.03
6: 3.03
7: 3.03
8. 8.30

IC2
1: 3.02
2: 3.03
3: 3.03
4: 0
5: 3.2-5.3
6: 3.5-5.1
7: 1.3-7.6
8. 8.29

Q1 and 2 (pinout as per GGG diagram)
G: 0.8-1.12
S: 3.02
D: 3.02

The bold readings on IC2 represent rapidly varying voltages, the range of which can be adjusted by turning the pot. Voltages at the gate of the JFETs also rapidly vary and can be modified by adjusting the trimmer and pot. I assume this is normal and while the source and drain voltages never change I noticed the resistance between (across?) these two legs also rapidly changes (oscillates?). So if my JFETs act as variable resistors and they are matched (I think) should I have phasing?


Sock Puppet

  • Guest
Re: Need help with GGG phase 45
« Reply #1 on: November 25, 2007, 05:22:03 AM »
You're right about the transistor orientation, there's a reference to it here:

http://remmelt.com/electro/

S.

remmelt

Re: Need help with GGG phase 45
« Reply #2 on: November 25, 2007, 10:24:59 AM »
:D


That's the Tonepad layout though. It sounds like you're on the right track, my effect started out as just clean as well. When I finally found the correct way to insert the transistors, there was still no phasing. The actual phase sound is on a very narrow band of the bias knob. Outside of that area, there's no phasing (I was not expecting this.)


lynessmy

Re: Need help with GGG phase 45
« Reply #3 on: November 26, 2007, 03:42:31 AM »
:D


That's the Tonepad layout though. It sounds like you're on the right track, my effect started out as just clean as well. When I finally found the correct way to insert the transistors, there was still no phasing. The actual phase sound is on a very narrow band of the bias knob. Outside of that area, there's no phasing (I was not expecting this.)



 ;) you need to tweak your pedal to that area. It is narrow....Jesus said...go into the narrow way .... ;D