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#1
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Marshall 2204 problem...
My new 2204 copy works - except for the presence control.
With no input and the master volume on zero, depending on the speaker cabinet the amp oscillates at 100Hz or much more. With one cab, the presence control actually controls the oscillation but with the other, there's no control possible even with all the controls on zero. Funny thing is that with the THD hotplate speaker attenuator, the oscillation disappears even with just 4dB attenuation. Any ideas guys? cb -- ================================= Some people have something to say... others have to say something! |
#2
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Found the problem - presence was out of phase so the "replacement" isn't an
accurate Marshall replacement. Emailing supplier for the proper spec sheet.... at least I only used a 16 ohm load on the highest impedance secondary... cb -- ================================= Some people have something to say... others have to say something! |
#3
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Just flipflop the thansformer wires that go to the plates of your power
tubes. That will fix your phase problem. BTW, once you really start pushing the volume and overdriving the phase inverter, the presence control really doesn't do much. Chris Berry wrote: Found the problem - presence was out of phase so the "replacement" isn't an accurate Marshall replacement. Emailing supplier for the proper spec sheet.... at least I only used a 16 ohm load on the highest impedance secondary... cb -- ================================= Some people have something to say... others have to say something! |
#4
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wrote in message
oups.com... Just flipflop the thansformer wires that go to the plates of your power tubes. That will fix your phase problem. BTW, once you really start pushing the volume and overdriving the phase inverter, the presence control really doesn't do much. Thanks... figured that one out with my plexi - very few controls work at extreme overdrive. cb |
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