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blackstar and with mis-matched impedance
February 8, 2013
5:09 pm
emaccarthy
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February 1, 2013
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I recently bought a HT20 combo with an upgraded speaker (swamp thang) pre-installed into it. I didn't like the sound of the speaker so I swapped it out for Celestion. The Celestion is an 8 Ohm so I plugged that into the middle output of the back pannel for a single 8 Ohm output. The swamp thang that came in it was plugged into the 16 ohm ouput but upon further inspection is actually an 8 ohm speaker. Was any damage done by having the 8 Ohm speaker plugged into the 16 Ohm output of the amp? I have searched the internet and it seems that people can't quite make up their mind as to if it is harmful or not in a tube amp…..

 

Help

February 10, 2013
2:38 pm
Bruce
NY
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i always match up ohms, i just follow that guideline. i cant say if something is harmful or not but i dont have to worry about it lol

February 11, 2013
3:03 pm
The Tone King
The Tone Lounge
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If your amp is working – chances are … you are fine.  If something was to have gone wrong – you would most likely either hear no sound – or you would have blown a fuse (which is there to protect an amp).  But, like Bruce noted – stay matched, and you're always good to go.  But in the event that you're not matched – I believe it to be this way :

 

An amp 4, 8 or 16 ohms into a 16 ohm speaker is okay.

(cab rated higher # than amp is okay).

 

The other way around can cause damage (too much load on the transformer).

(cab rated lower # than amp is NOT okay).

Example:

If your amp must be at 16, don't run it into anything less than 16.

If your amp must be at 8, don't run it into anything less than 8.

If your amp must be at 4, don't run it into anything less than 4 (like 2 4 ohm cabinets, which would make 2 ohm load).

 

Also remember – when you are using multiple cabinets, or multiple speakers – depending on how it's wired – it can often be 1/2 the impedance.  (2-16 ohm speakers can be an 8 ohm load, 2-8 ohm speakers can be a 4 ohm load, and 2-4 ohm speakers can be really bad for your amp!!)

 

LONG story short :

1) amps are meant to be matched. 

2) if your amp is working – chances are – it's okay.

3) when in doubt – always check w the manufacturer!!

4) it never hurts to bring a multimeter to the gig, especially if you are using your amp head w someone elses cabinet.  Just because the label says X ohms, doesn't mean someone didn't swap the speakers, that would make the label wrong!!

 

Hope that helps!

 

 

 

 

February 11, 2013
11:57 pm
Bruce
NY
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February 28, 2011
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cab rated higher than amp is ok, i just remembered I have a 1x12 speaker that is 16 ohms and rated for 30 watts, I bought a head that is 40 watts switchable to 20 watts and it only has a 4 and 8 ohm output but under 8 it says it can be hooked into a 16. In my manual it says it compromises the sound a little bit.

February 12, 2013
8:02 pm
emaccarthy
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February 1, 2013
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The amp seems to be working and sounding fine.  Even though the amp was run at 16 Ohms with an 8 Ohm speaker does anyone think damage was done?

February 12, 2013
8:59 pm
Bruce
NY
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im not a technician and the amp isnt in front of me so who knows. were you playing at loud volumes?

February 12, 2013
10:21 pm
The Tone King
The Tone Lounge
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June 20, 2009
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Same … I really have no idea. If you are in doubt – bring it to a tech, and have them check it out.

If I was to take a guess … if it plays, and sounds okay – chances are – it's okay.  Reason being if something was wrong, you'd most likely blow a fuse, or hear noise / fizz / or very low volume – indicating a failure.  But – if it's playing fine, I suspect it may be fine. 

But again – if you are in doubt – bring it to a tech, and have them check it out.  There's no way to know w out having someone open it up and check it out.

AND – don't open it yourself – the inside of amps have LETHALLY high voltages.  Again – bring it to a tech if you're wanting to get a clean bill of health on the amp.

Hope that helps!  Good luck!

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