Turn on the amp, and it takes a few minutes to achieve normal volume

FuzzOff

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593
I have a Dr Z Stingray, which is one loud mamma jamma. I noticed that when I first turn it on, it's not achieving full volume (this thing should kill small rodents on 3). The power tubes have pretty low hours. Could preamp tubes cause this? Maybe I have a bad power tube.
 

FuzzOff

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593
Yes, true in my experience. I've had this amp for 4-5 years and it seems to be longer than normal.
 

wall_of_sleep

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812
Sorry about that. This sounds a little trickier.
How much longer? Is everything normal afterwards?

Some stage along the line is taking longer to bias. Since your power tubes are new, it wouldn't hurt to double check the rectifier and preamp tubes with a backup set. Obviously any tube can go bad at anytime. It may be hard to say without having the amp open on a bench.
 
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donnyjaguar

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4,201
I think you need to quantify how long it takes to get to full volume from a cold start.
If it started doing this and there have been no changes in the tubes (or any mods either) then it tells me something is awry.
 

FuzzOff

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593
the range is 5-7 minutes from cold start to full volume. I also noticed a bit more distortion at my last gig. Stingray is a super clean amp and you have to push it hard to get any dirt. I was getting dirty tones on 3. Sounded great! But not natural for a Ray.
 

FuzzOff

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593
I thought rectifier first too. I will pop in a spare and see what happens, thanks for the ideas.
 

donnyjaguar

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4,201
Interesting, indeed. That's a three-knob amp so not a lot of components in there I'm guessing. If you think about it, any unusually slow warm up can only be caused by a capacitor not charging quickly enough. This is generally due to either the resistor feeding it being too high resistance or the capacitor itself having some internal resistance.
 

wall_of_sleep

Member
Messages
812
Donny's on the mark. On a bench you'd be able to watch the voltages climb to pinpoint your power supply or component issue. I don't think anyone would recommend this testing to someone inexperienced simply because of exposing a live chassis. After checking the tubes, it will likely be time to send the amp out for repair.
 




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