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Discussion in 'The Workbench' started by matttornado, Jan 27, 2020.
But how can the PI all of the sudden become reversed without anyone doing it?
I am with @matttornado.
Exactly how would a PI get reversed without modifying the board and or maybe the wiring?
I'm suggesting a test, it's a simple one.
This happened to me too not so long ago. I decided to try a new production Mullard in V3 of my amp and it killed the tone. Mushy, bassy, terrible sounding. Replaced it with an old one and the amp went back to normal. Glad yours is sounding great again.
tests are over, well done getting it sorted, congratulations.
thanks for all the input everyone.
here's another observation:
I said previously that everything seems fine now. The other night it sounded bassy again so I recorded it with my cell phone and it sounded way different all together but the bassiness was not there at all - not even close.
I alos been noticing too, and this was suggested earlier in the thread, that my hearing has become very sensitive to lower bass frequencies. Especially with a cranked PA and vocals.....
Well, the problem is back again. Ugh
I'm going to re-read this thread and start troubleshooting.
You've got a loose connection in the amp or maybe a component is experiencing intermittent failures.
That's going to take some time on the bench to troubleshoot. Not sure of your troubleshooting skill level, but for this it is going to take some good skills and some time to track down.
It may be something as simple as a bad solder connection on the bright cap. Or it might be a failed mustard cap with ring cracks around one end, letting moisture get into the capacitor's guts.
thanks for your reply. yes it’ll be tough. I just finished measuring all of the voltages at every pin, for all 7 tubes. i’ll post them tomorrow at work. I have no leaking caps and all of the voltages look ok to me compared to a voltage chart i have from the metro forum.
perhaps if you look at it, you might see something?
Got a scope? It might be very helpful, particularly if you also have an audio signal generator and a cable to get it into the amp.
Take off the attenuator and stop jumping the channels. Plug into the high treble channel. Does that make the bass less boomy and make the bass control act right?
thanks for the reply!
Not using attenuator and not jumpered, bass control works fine as all other controls. I'm plugged into the high treble channel.
The amp works great it just sounds very bassy especially when I palm mute the Low E and A strings.
I always been able to jump the channels and crank the bass on 10 without it every being to bassy. been doing that for many years.....
I wish! I might grab one off of ebay.
The problem with that is I don't know what I'm looking at, what looks good or what is bad. lol
That’s the opposite of my experience. Jumping the channels was always too dark for me, had to keep channel 2 very low. And I’ve never had any amps where putting the bass on 10 sounded good. Your current description sounds about normal to me.
PS, some closed back cabs really emphasize bass.
I had similar problems in a 2205 couple
years ago, drove me almost nuts, sounded
perfect one day and the next time like boomy
ugly horseshit. Was going through it with fine
comb so to speak but couldnt locate the
problem. I suspect compromised ceramic
brightcaps, there are 2 in there directly
on a socket which has over 500volts on
I installed couple brightcaps and it sounds
and feels like my 2203 now, so i keep it like
Maybe check the brightcaps in your amp?
I either use an open back 2x12 Avatar with vintage 30's or an Marshall 4x12 with 25 watt greenbacks & I get the same results.
Thanks! Yep thought about that too. Will check into it - again.