How to troubleshoot tube guitar amp noise using a dummy load resistor
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- čas přidán 3. 06. 2019
- A great Tech Tip from D-lab electronics. If you are planning to troubleshoot noise hiss buzz etc in your amplifier, make sure to utilize a dummy load resistor. If you use the internal amplifier speaker, the speaker can become a microphone, making everything appear sensitive, fooling you! The resistor technique snubs out that possibility. For your reference, you can use a low wattage type, since you are not applying much output. No need for a giant 100 watt resistor. I used 25 watt type, since I had a few spares around. Always be cautious when working around these high voltage devices. Have fun!
I never thought of that happening with the speaker… great video Terry thanks for sharing it
Excellent tip Terry !! I forgot that a speaker is also a microphone !!
Mine came from a junkyard in the 70's. The owner, Fred, called it his "Big Dummy" load. He had his son Lamont get it for me.
Once again you taught a new tech tip. All the Best man. B
Thats really cool and totally makes sense thanks Dlab!
Dang, Terry, you are giving away all your secrets! Thanks, and since I don't do amp repairs in any form (other than watching you, and Uncle Doug, and El Paso Amps, and Brad, and some others that I won't mention in hopes of not offending anyone), I won't be a competitor. Thumbs up, as always.
Thanks DLab! Great info on using a dummy load otherwise someone like myself could be running in circles!
What a genius! Even your voice could affect the readings.
Great tip. Been in the game for a while, still always love learning!
i'd like to see a video about the oscilloscope, basic operations/explainer, and a general overview as to how it pertains to tube amplifier testing/ maintenance. always been mysterious yet intriguing to me. thanks for all the great vids!
Now that’s a good tech tip right there. Thanks for sharing your discovery/knowledge on this!
Damn fine way of checking.
Ok, gotta make myself a dummy load resistor now..
Terry I have been watching your videos for some time and getting a lot of useful information. I wanted to let you know how much I enjoyed this no nonsense presentation. It was the best ever. Give us more like this. Thanks for sharing.
Excellent tip! Many thanks for putting this video out there.
Great tip d-lab... Love your process!.... I like to reproduce problems in troubleshooting that's why I'm diggin' this channel!! Excellent work Terry....
I never would have thought of that, thanks. I have filed it away in the deep recesses of my twisted mind.
That's great information and a clear demonstration of the best way to test. Thanks for posting this.
Hi Terry, thank you for another educational video.
Our test-panel systems at work (audio repair shop) have switching between dummy loads (4 or 8 ohm, selectable) and speakers ---- but the speakers are on a shelf four feet above the work bench, far enough away to be at least somewhat mechanically decoupled from the amp chassis and any microphone-like behavior is minimal; and therefore we can leave the speakers "on" when performing a tap test, and poking/prodding at the circuit board. We put a 400 hz tone through the amp so that noise spikes or pulses can be seen on the scope, and simultaneously use a distortion meter so we can look for a jump in distortion level as we do our tap test.