Projects are pilin' up

mcblink said:
Okay so will damage occur if he's using two 16 ohm cabinets without switching the amp to 8 ohms?

Is this the cause of this issue?
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I don't think that was an impedance issue.
I think the tube socket wasn't making good contact with 1 of the pins.
This causes the pin to overheat.

It doesn't look like arcing, just overheating.

But in the future 2 X 16 ohm cabs should be set to 8 ohm on the amp.
 
mcblink said:
Okay so will damage occur if he's using two 16 ohm cabinets without switching the amp to 8 ohms?

Is this the cause of this issue?
Click to expand...
I don't think that was an impedance issue.
I think the tube socket wasn't making good contact with 1 of the pins.
This causes the pin to overheat.

It doesn't look like arcing, just overheating.

But in the future 2 X 16 ohm cabs should be set to 8 ohm on the amp.
 
Thatbastarddon said:
Yes. Damage will occur if the amp expects to see a 16 Ohm speaker load, and it actually gets an 8 Ohm load.
Click to expand...
So what happened here is he inadvertently had a mismatch (in the wrong direction) because his amp being set to 16 and essentially being plugged into 8 ohms (because two 16ohm cabinets = 8 ohms)

Sending 8 to 16 is okay, but sending 16 to 8 is not, but his amp sent 16 to 8 because he forgot to flip the switch....
 
LRT said:
Just checked ohms on both cab and both read 15.8 ohms so it seem those cabs are good. The 1960 has a mono/sterio switch and the 4ohm and 16ohm or 8hom using both jacks.

Could this plate be a potential problem and should i wire in direct jacks eliminating the board?
Click to expand...

I experienced a failure of one of those switch plates.
mcblink said:
View attachment 66639



Switch failure??
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I despise them.
 
mcblink said:
So what happened here is he inadvertently had a mismatch (in the wrong direction) because his amp being set to 16 and essentially being plugged into 8 ohms (because two 16ohm cabinets = 8 ohms)

Sending 8 to 16 is okay, but sending 16 to 8 is not, but his amp sent 16 to 8 because he forgot to flip the switch....
Click to expand...
Very likely....yes. Explains the smoked power tube socket too....possibly.
 
Amp Mad Scientist said:
I don't think that was an impedance issue.
I think the tube socket wasn't making good contact with 1 of the pins.
This causes the pin to overheat.

It doesn't look like arcing, just overheating.

But in the future 2 X 16 ohm cabs should be set to 8 ohm on the amp.
Click to expand...
Thatbastarddon said:
Yes. Damage will occur if the amp expects to see a 16 Ohm speaker load, and it actually gets an 8 Ohm load.
Click to expand...
So we're fully confused now lol
Was there an impedance issue that contributed to the socket/tube failure or not?? Lol
In any case, replace socket and set to 8 ohms for future reference (when using 2 cabs)
 
mcblink said:
Sending 8 to 16 is okay, but sending 16 to 8 is not, but his amp sent 16 to 8 because he forgot to flip the switch....
Click to expand...
I look at it this way instead: the speaker load is what the amp “sees”...if the amp expects to “see” 8 Ohms, but it actually gets 16, all is well(because more is ok, right?). But....if the amp expects to ”see“ 16 Ohms, and it only gets 8 Ohms....things are gonna get heated. Don’t try to shortchange the output transformer....things will get bad.
517309A2-41CD-42B9-9482-28771B181597.gif
 
I'm glad I got to see LRT fry his poop.
I only have one cab, so I haven't run into these problems before......and now I won't either because I learned my lesson from it

My amps also don't have confusing switches and labels on the back of em either though....pretty straightforward
 
Thatbastarddon said:
I look at it this way instead: the speaker load is what the amp “sees”...if the amp expects to “see” 8 Ohms, but it actually gets 16, all is well(because more is ok, right?). But....if the amp expects to ”see“ 16 Ohms, and it only gets 8 Ohms....things are gonna get heated. Don’t try to shortchange the output transformer....things will get bad.
View attachment 66646
Click to expand...
Thats how i began to understand it over time: more speaker load to the amp is ok vs not enough. Too little impedance to the amp means its amperage kicks up too high and begins burning transformers and resistors, more impedance just chokes the performance of the amp. Might not sound as loud or as great as it should but its seems to be safer.

I run what Mesa Boogie would call a safe-mistmatch on my JCM2000 DSL50: its running an 8 ohm cab and a 4ohm cab at 4ohms on the amp. Comes around 5.3-5.6ohms when its looking for 4, so its slightly more but over the threshold rather than under it
 
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