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Did I blow my tube amp?

So here's the story: I recently received my tube amp and replaced the power tubes. So naturally, I wanted to bias them to make sure they work properly. I've never done any biasing before and checked some youtube videos on biasing. One of the youtube video had a Manley Stingray connected to power, no input signal, and NO speakers connected. I did the same. After the biasing is done, I connected the speakers and input signal, but for some reason so sound came out.

So the question is: did I blow my output transformer? Simply by not connecting the speakers while biasing or just having the amp on for a short while? From what I have read, it should be ok to have no speakers connected as long as there's no input signal.

I had another tube amp before this, and turned it on one time without speakers connected and it worked flawlessly after.

Could you guys shed some knowledge or personal experience on this topic?
vu001
jea48
2,944 posts
 
Jea48, Regarding your comment "(Dumb way to build something)". The output transformer case may be grounded. Most people use terminated speaker cables eliminating this problem.
04-07-12: Rrog

Rrog,

I was only repeating the info from the user manual of the Stingray of that particular production model.

Here is the full text.

"IMPORTANT: DO NOT LET THE BANANA PLUGS OR SPEAKER CABLE CONNECTORS (TOUCH) THE TRANSFORMER DIRECTLY BEHIND THEM.
This can short out the amplifier and possibly cause damage to the Stingray, besides losing signal."

See page 7 of link below. Diagram is also shown.

http://manleylabs.com/PDF/HIFI_Manuals/Hi-Fi/Stingraymanual32001.pdf

I notice the design flaw was changed on later models.
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wilsynet's avatar
wilsynet
264 posts
 
It now needs to be repaired. Looks like its time to either send it to the manufacturer or to a repair shop for diagnosis.
ebm
5,165 posts
 
Your in a world of hurt!!
larryi
1,972 posts
 
It is not that likely that having no speakers connected accounts for your problem. That could overload the primary side of the output transformer, but, that usually happens when there is an input and the amp is supposedly putting out a lot of power, except, there is no load attached. If you had no signal going to the input, I don't think you caused the problem.

Perhaps an output tube was bad (shorted) and that caused the main fuse to blow. Check all fuses first; if you are lucky it is just the fuse.
jea48
2,944 posts
 
I ran across an interesting white paper by
Hartley Peavey.
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