68 plexi
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- lautmaschine
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Re: 68 plexi
Was anyone able to determine if the v1b resistor is 2k7?
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Re: 68 plexi
I'd bet it's a 820.
- neikeel
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Re: 68 plexi
+1julkke wrote:I'd bet it's a 820.
An 820 cn be a bit gritty with humbuckers and give a bit of fizz (not a problem with the tones here) if trying to play cleanly but a 1k5 is a compromise between that the 2k7.
Neil
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Re: 68 plexi
I gotta try that 1.5k because I can't decide which do I like better, 2k7 or 820r.neikeel wrote:+1julkke wrote:I'd bet it's a 820.
An 820 cn be a bit gritty with humbuckers and give a bit of fizz (not a problem with the tones here) if trying to play cleanly but a 1k5 is a compromise between that the 2k7.
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Re: 68 plexi
I have figured out why some of those 50watt 1987 series amp gain up so quick
Akme Guitars
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Re: 68 plexi
and...?Maverick wrote:I have figured out why some of those 50watt 1987 series amp gain up so quick
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Re: 68 plexi
I think a big bright cap(5000pf)?
Erik
Erik
- neikeel
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Re: 68 plexi
Seem to remember mentioning that one or twice before, a big bypass cap on the pot is not a 'bright cap'!!
Neil
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Re: 68 plexi
I agree with you,but it is one of the reasons that they are a bit gainy at lower volume settings.
It is more of a bandpass depending of where the potmeter setting is.
Erik
It is more of a bandpass depending of where the potmeter setting is.
Erik
- neikeel
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Re: 68 plexi
We agree! A few others do not.............gloeidraad wrote:I agree with you,but it is one of the reasons that they are a bit gainy at lower volume settings.
It is more of a bandpass depending of where the potmeter setting is.
Erik
Neil
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Re: 68 plexi
Old thread that wooperplate linked.
Did the plate volts get determined? Im betting their low.
Also I wonder what the cathode follower resistor is. It would be easy to mistake a 10k as a 100k. That could add some compression.
What was the feedback resistor connected to?
Did the plate volts get determined? Im betting their low.
Also I wonder what the cathode follower resistor is. It would be easy to mistake a 10k as a 100k. That could add some compression.
What was the feedback resistor connected to?
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Re: 68 plexi
The Drake 1202-118 PT's were fairly consistant voltage wise so I would venture to say the plate voltage was normal.
I've seen a fare share of anomalies in the Marshall circuit but a 10K resistor in place of a 100K for the cathode follower isn't one of them.
The nfb is taken from the output solder terminal on the Selector as opposed to a particular secondary tap.
I've seen a fare share of anomalies in the Marshall circuit but a 10K resistor in place of a 100K for the cathode follower isn't one of them.
The nfb is taken from the output solder terminal on the Selector as opposed to a particular secondary tap.
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Re: 68 plex
I was looking at an old thread talking about how transitional amps from this era are often wired incorrectly on the b+ line with the last 10k dropping resistor wired out of the circuit essentially.
viewtopic.php?f=16&t=44511&hilit=50k+mid+pot&start=15
All of the links to uploaded photos showing examples are non existent. With This amp being from that era and also having the 10k oriented on the board in a way I have only seen common In this era amp I assume that this may be suspect as well. Any knowledge?
Thanks
Charlie
viewtopic.php?f=16&t=44511&hilit=50k+mid+pot&start=15
All of the links to uploaded photos showing examples are non existent. With This amp being from that era and also having the 10k oriented on the board in a way I have only seen common In this era amp I assume that this may be suspect as well. Any knowledge?
Thanks
Charlie
Musicians are like a bowl of cereal
If they aren't Fruits or Nuts they're Flakes
If they aren't Fruits or Nuts they're Flakes
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Re: 68 plexi
As someone else mentioned I bet those CC 10ks have drifted well out of spec.
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Re: 68 plexi
Those are both 8k2 in this amp, and I am referring to the 10k Iskra terminating near the potentiometers by the dual .022uf mustards. Apparently, according to Tazin in the linked thread I provided, the transition lamps of this period often wired this incorrectly.
Charlie
Charlie
Musicians are like a bowl of cereal
If they aren't Fruits or Nuts they're Flakes
If they aren't Fruits or Nuts they're Flakes