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Help! Soldano SLO modded amp is whistling


 
3/20/2004 2:16 PM
Bill D.
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Help! Soldano SLO modded amp is whistling
This is sort of a follow up of my earlier post,but now I've got a new problem, the amp starts whistling when I get the master volume past 2, I've tried just about everything I can think of that could cure the problem, so now I think I need some expert advice.The amp as I said in the previous post is a Laney 50 watt pro tube lead, I pretty much followed the SLO schematic, minus the clean channel, duel cathode followers and FX loop, it's a basic single channel amp and I'm losing my mind trying to figure out how to solve this problem. I'm wondering if anyone else has had a similar experience when using this circuit, and if there is some sort of method of dealing with this problem, any advice would be so greatly appreciated.  
 
Thanks, Bill
 
3/20/2004 2:28 PM
rooster
Check your layout and grounding of the NFB loop off your speaker jack, and make sure that the attenuator resistor is located close to the PI input. If it's off the speaker jack, you'll have the same problem I did.  
 
rooster.
 
3/20/2004 2:45 PM
Bill D.
email

So what your saying is to get the NFB wire off the jack itself and put it on one of the other taps? And what you mean by attenuator resistor is the grid stopper? Anyways thanks a lot man and I am warming up my soldering iron as we speak to give this a try.  
Thanks, Bill
 
3/20/2004 7:24 PM
Bill D.
email

Hey Rooster, you were right! It was a NFB issue, the resonance knob I put in was to blame. I had the resonance on the front panel right next to the input jacks, the NFB signal was mixing with my input signal and thus my whistling problem. My friend does want the resonance knob in there, so I'm wondering if I hook up the resonance knob wires with shielded wire, would that work? Anyways rooster, thanks for the tip, you really made my day!  
 
Thanks, Bill
 
3/23/2004 2:15 AM
jeremy
email

whenever you run somethign from the power end to the front of an amp, you should shield it. good luck!!  
 
jeremy
 
3/24/2004 1:33 AM
rooster
You're very welcome. You can imagine how I figured that out.... :O)  
 
rooster.
 
3/24/2004 10:39 PM
Bill S. Re: What song is it whisling?
LOL
 
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