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Ampeg PF50T impedance selector

mickebas

mickebas

Sep 7, 2008
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#1
I know this has been covered here before but I can't seem to find it.
My question is simply 'how do I know that the impedance selector is set to 4 or 8 ohms'?
I think it should be obvious but I don't think Ampeg made a good design as far as this switch goes. It could mean either way.
Does having the selector like below meaning it's in 4 or 8ohm mode?

Skärmavbild 2022-08-11 kl. 13.00.54.png
 
#3
Element Zero said:
To me, clearly, the tab on the switch is set to 4 ohms. Not sure how when looking at the actual switch and flip it back and forth there's really any confusion.
Click to expand...
Ok, Thanks!
Maybe it's just my logical thinking that's different ;) Also since it's all actually black and not white like in the manual, to me it could be seen both ways. Don't know how much it could hurt my PF115 cab though if I was to set it wrong, but the great thing about this forum is getting info like this quick :bassist:
 
#5
mickebas said:
Ok, Thanks!
Maybe it's just my logical thinking that's different ;) Also since it's all actually black and not white like in the manual, to me it could be seen both ways. Don't know how much it could hurt my PF115 cab though if I was to set it wrong, but the great thing about this forum is getting info like this quick :bassist:
Click to expand...
Does the manual state you can run the amp in 4 ohm operation while using an 8 ohm cab?
 
#10
mickebas said:
I know this has been covered here before but I can't seem to find it.
My question is simply 'how do I know that the impedance selector is set to 4 or 8 ohms'?
I think it should be obvious but I don't think Ampeg made a good design as far as this switch goes. It could mean either way.
Does having the selector like below meaning it's in 4 or 8ohm mode?

View attachment 4778554
Click to expand...
It looks more confusing than on paper than it is in real life. I have one of these, and if you look at the switch and flip it back and forth a couple times and understand how it works if you need, the indication is pretty clear.
 
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#11
jdjk7 said:
It looks more confusing than on paper than it is in real life. I have one of these, and if you look at the switch and flip it back and forth a couple times and understand how it works if you need, the indication is pretty clear.
Click to expand...

It's probably just me ;) Now that I got the answer it's clear but just looking at it in the faint light of a dark stage it was not that clear :nailbiting: Now I just need to remember this :thumbsup:
 
#12
mickebas said:
It's probably just me ;) Now that I got the answer it's clear but just looking at it in the faint light of a dark stage it was not that clear :nailbiting: Now I just need to remember this :thumbsup:
Click to expand...
Oh, I wasn't sure if you had the amp in hand or if you were doing the thing I do which is "memorize the manual forwards and back before you buy"... Yeah, unless you have a good light on it it could be hard to tell what's going on.

It's a bit of a design conundrum, because the switch has to be accessible but also can't be something that gets flipped accidentally.
 
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#13
jdjk7 said:
Oh, I wasn't sure if you had the amp in hand or if you were doing the thing I do which is "memorize the manual forwards and back before you buy"... Yeah, unless you have a good light on it it could be hard to tell what's going on.

It's a bit of a design conundrum, because the switch has to be accessible but also can't be something that gets flipped accidentally.
Click to expand...

Yes. The thing is I've been down this route before using different cabs and now I wasn't sure, since it's been a while, in what position I left it. But hopefully this is the last time I need to post the question, I think I finally got it ;)
 
#14
mickebas said:
--- snip --- Don't know how much it could hurt my PF115 cab though if I was to set it wrong, but the great thing about this forum is getting info like this quick :bassist:
Click to expand...
I'm hazy on this but as I recall if the output impedance isn't set correctly on a tube amp it doesn't harm the speaker, I think it either wears the tubes faster, or overheats the output transformer which could eventually melt down. Maybe both. Either way, don't do it.
 
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#17
mickebas said:
Yes. Thanks to TB I learned how the switch should be set.
But I can't find anywhere in the manual an explanation of the main question, what is on/off of the switch. But I figured it out now thanks to you guys at TB so all is good.
Click to expand...
I get it. My pet peeve is with ground lift buttons. I'm to assume pushed in means the ground is lifted? Assumptions......
 
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#20
mickebas said:
I know this has been covered here before but I can't seem to find it.
My question is simply 'how do I know that the impedance selector is set to 4 or 8 ohms'?
I think it should be obvious but I don't think Ampeg made a good design as far as this switch goes. It could mean either way.
Does having the selector like below meaning it's in 4 or 8ohm mode?

View attachment 4778554
Click to expand...
Switch moves left and right. Move the switch toward the impedance you want selected.
 
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