I'm sure the answer is obvious and I'm brain farting but, I've acquired a Ceriatone OTS that sounds beautiful (clean) on the 16 ohm tap running into a 16 ohm load or any load but distorts on either the 4 or 8 ohm tap running into any load. The distortion isn't necessarily unpleasant but definitely unwanted and shouldn't be there.
I've tried cleaning the rotary selector contacts to no effect.
The only solution my inept brain is coming up with is bad OT.
Apparently, it was fine until someone replaced the PT with a MM unit.
I'm not very familiar with this "D" style circuit.
Update- I also tried bypassing the selector switch.
Ceriatone OTS 50w distorting on 4 & 8 ohm taps.
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mrbadwr3nch
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Ceriatone OTS 50w distorting on 4 & 8 ohm taps.
Last edited by mrbadwr3nch on Sun Oct 12, 2014 10:33 pm, edited 1 time in total.
Chris Brandt
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tele_player
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Re: Ceriatone OTS 50w distorting on 4 & 8 ohm taps.
When amp is distorting, does presence control still function?
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mrbadwr3nch
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Re: Ceriatone OTS 50w distorting on 4 & 8 ohm taps.
It does not appear to be functioning...
NFB resistor?
The NFB circuit is a little strange on this thing, just looking at the layout.
NFB resistor?
The NFB circuit is a little strange on this thing, just looking at the layout.
Chris Brandt
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Re: Ceriatone OTS 50w distorting on 4 & 8 ohm taps.
I'd definitely verify that NFB loop is correct.
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mrbadwr3nch
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Re: Ceriatone OTS 50w distorting on 4 & 8 ohm taps.
So, I'm going over the layout verifying the NFB circuit and lo and behold, the 390 ohm resistor after the NFB resistor was bypassed with a 22uf electrolytic for some reason.
Removed the cap and all is good in OTS land.
Can you explain why someone would do this?
Removed the cap and all is good in OTS land.
Can you explain why someone would do this?
Chris Brandt
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Re: Ceriatone OTS 50w distorting on 4 & 8 ohm taps.
I won't even try to guess.mrbadwr3nch wrote:
Can you explain why someone would do this?
Re: Ceriatone OTS 50w distorting on 4 & 8 ohm taps.
The resistor is near the cathode (kinda). An inexperienced modder might think "hey lets bypass this with a cap and bump up the gain", thinkings its a cathode resistormrbadwr3nch wrote:So, I'm going over the layout verifying the NFB circuit and lo and behold, the 390 ohm resistor after the NFB resistor was bypassed with a 22uf electrolytic for some reason.
Removed the cap and all is good in OTS land.
Can you explain why someone would do this?
Re: Ceriatone OTS 50w distorting on 4 & 8 ohm taps.
Ha ha....I could see that happeningChrisM wrote:The resistor is near the cathode (kinda). An inexperienced modder might think "hey lets bypass this with a cap and bump up the gain", thinkings its a cathode resistormrbadwr3nch wrote:So, I'm going over the layout verifying the NFB circuit and lo and behold, the 390 ohm resistor after the NFB resistor was bypassed with a 22uf electrolytic for some reason.
Removed the cap and all is good in OTS land.
Can you explain why someone would do this?