I put the Rich II ppimv the one that George likes on my 50 plexi and I was playing and went to adjust treble and It does nothing and bass and mid do very little!! I took the ppimv off thinking that had something to do with it and it still the same everything worked fine the last time I played it before the ppimv mod.
anyone have an idea where to start?
Metro 50 watt 68 specs EQ trouble
Moderator: VelvetGeorge
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Turd Ferguson
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neikeel
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Re: Metro 50 watt 68 specs EQ trouble
It sounds as if the feed from the treble pot to the tone stack has come adrift either on the trebe pot or elsewhere.
If you look at the schematic and the layout it is the wire that comes from the treble pot that is nearest the other tone controls.
The way these controls work is the signal comes in from the other outer lug from the tone stack capacitor and then into the pot. The middle lug is the output to the PI.
The EQ works by subtracting frequencies via the outer lug and dumping them to ground vial the ground wire on the mid pot (which could be another point of problem if the controls are not grounded, so disturbing that ground might also have happened.
Check both aspects out.
I should also mention that quite a lot of the silver mica caps in the tone stack have been failing. Quite why I do not know as they are rated for 500v but maybe they do not take being heated up too much if you slightly overdo it when building
. Altough that should not be your issue as the cap is before the signal goes to the pi so typically you get loss of signal or obnoxious oscillations when the cap is failing/has failed.
Please post back when you are done
If you look at the schematic and the layout it is the wire that comes from the treble pot that is nearest the other tone controls.
The way these controls work is the signal comes in from the other outer lug from the tone stack capacitor and then into the pot. The middle lug is the output to the PI.
The EQ works by subtracting frequencies via the outer lug and dumping them to ground vial the ground wire on the mid pot (which could be another point of problem if the controls are not grounded, so disturbing that ground might also have happened.
Check both aspects out.
I should also mention that quite a lot of the silver mica caps in the tone stack have been failing. Quite why I do not know as they are rated for 500v but maybe they do not take being heated up too much if you slightly overdo it when building
. Altough that should not be your issue as the cap is before the signal goes to the pi so typically you get loss of signal or obnoxious oscillations when the cap is failing/has failed.Please post back when you are done
Neil
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Turd Ferguson
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- Joined: Sun Dec 22, 2013 11:35 am
- Just the numbers in order: 13492
Re: Metro 50 watt 68 specs EQ trouble
Thanks Neikell,
all wires and grounds check good but on a closer look I mistakenly put a 100 pF silver mica cap in it when I was tinkering with the tone stack it now has a 500pF EQ seems a little better but I fill that the EQ could be more usable any info on more usable EQ? the amp is 68 specs all but the Rich ll mod on it!!
all wires and grounds check good but on a closer look I mistakenly put a 100 pF silver mica cap in it when I was tinkering with the tone stack it now has a 500pF EQ seems a little better but I fill that the EQ could be more usable any info on more usable EQ? the amp is 68 specs all but the Rich ll mod on it!!