So, I finished my Rocket last week, and it sounds really great. I am gonna love this amp. I am considering installing a VVR too. It should make it more versatile since there is no MV.
But, there is a crackling noise that I need to resolve. And, I am pretty sure that it is at least partly caused mechanically.
I have found that if I hit a chord sharply, the crackling would start while the chord was sounding and then continued for a second or so after I muted the chord. It is pretty consistantly reproduceable. So at least I have a good way to do my testing.
I then tried playing through a different speaker cabinet, and the crackling stopped. So I wondered if it was the original cab? I then took the head off of the first cabinet and hooked into it again. and the crackling was gone. So, no it's not the cabinet. I put the head back up on the cab, and the crackling noise was back.
So, it certainly seems that my speakers and cabinet are fine, and that the problem occurs only when the head is sitting on the speaker cab in use. Vibrations are at play here.
Any thoughts? Could it be related to the 4 "floating" screen resistors or the 4 "floating" grid resistors? Anybody else experience this, and come up with a solution?
Thanks,
Steve
Crackling Rocket
Moderators: pompeiisneaks, Colossal
Re: Crackling Rocket
Check for bad solder joints everywhere and check the wiring especially on the pots. Use a magnifying glass to view.
Mark
Mark
Re: Crackling Rocket
+1 what Mark said.
And also, I had a similar problem last winter, identical symptoms that you describe. I checked solder joints till I was blue in the face. It finally turned out to be an orange drop cap. They can be fragile with the leads. The leads can break off internally and then with vibration, it makes intermittent contact.
Hook the amp up to a scope and feed a signal into it. While watching the trace on the scope, ping the caps with a chopstick. Watch for a trace that goes all jumpy and erratic. This is how I found my bad cap (bass cap in the tone stack). Note, however, that orange drops are a sensitive cap and even good ones will exhibit some "jiggles" when tapped.
And also, I had a similar problem last winter, identical symptoms that you describe. I checked solder joints till I was blue in the face. It finally turned out to be an orange drop cap. They can be fragile with the leads. The leads can break off internally and then with vibration, it makes intermittent contact.
Hook the amp up to a scope and feed a signal into it. While watching the trace on the scope, ping the caps with a chopstick. Watch for a trace that goes all jumpy and erratic. This is how I found my bad cap (bass cap in the tone stack). Note, however, that orange drops are a sensitive cap and even good ones will exhibit some "jiggles" when tapped.
Re: Crackling Rocket
Interesting tip about using the scope - thanks. So, a minor jiggle is OK, but if the cap is bad internally, it would have a much more severe impact on the waveform? I suppose a bad resistor do the same? I'll have to give this a try.
Re: Crackling Rocket
My least favorite thing about OD caps is the fact that the leads are not soldered to the foil!!! If you open one up, the foil is just crumpled on either side and the lead just sort of jammed in there. Makes me want to make my own caps...