Is it safe to use an 8 Ohm cab with a 16 Ohm output on amp?

[Simon Dorn]

Yeah I imagine not being used for years had let all sorts build up inside the jack connection, I'm glad it worked for you though.

Unfortunately the ram it method didn't work for me, and the amp is also now doing the same thing on one of the 16 Ohm outputs, so it didn't fix it like I thought.

I will still get some more contact cleaner though to give everything a good clean, then decide wether to take it to an amp tech or save the money for a new amp head.


Thank you! I never imagined using a 4 Ohm cab with a 16 Ohm output to be safe where it is such a difference, but reading the article it seems to follow what they call the 25% rule and is OK, at least to Hughes and Kettner. I didn't realise it was the opposite, using a higher impedance cab with a lower impedance output that could potentially damage things by increasing voltage in the tubes for it to work.

The only thing I would be a bit worried about is that using a lower impedance cab increases the current, could this potentially stress the output transformer or would it be the transformer trying to put out more volts that is the issue?

At least they also say they have never even been able to put a tube amp out of its comfort zone, let alone leave one broken! I guess it would be a lot worse to run an amp with no load as this is when things can break.

Can't answer your specific question. I don't know more than the Guys that wrote the Article. I just found it to be pretty enlighting.
But yes, no load leads to failures. I'm in the process of making a little clip, to showcase the impedance-mismatch effect on sound.

 

[Simon Dorn]

Yeah I imagine not being used for years had let all sorts build up inside the jack connection, I'm glad it worked for you though.

Unfortunately the ram it method didn't work for me, and the amp is also now doing the same thing on one of the 16 Ohm outputs, so it didn't fix it like I thought.

I will still get some more contact cleaner though to give everything a good clean, then decide wether to take it to an amp tech or save the money for a new amp head.


Thank you! I never imagined using a 4 Ohm cab with a 16 Ohm output to be safe where it is such a difference, but reading the article it seems to follow what they call the 25% rule and is OK, at least to Hughes and Kettner. I didn't realise it was the opposite, using a higher impedance cab with a lower impedance output that could potentially damage things by increasing voltage in the tubes for it to work.

The only thing I would be a bit worried about is that using a lower impedance cab increases the current, could this potentially stress the output transformer or would it be the transformer trying to put out more volts that is the issue?

At least they also say they have never even been able to put a tube amp out of its comfort zone, let alone leave one broken! I guess it would be a lot worse to run an amp with no load as this is when things can break.

Here you go:

Thread 'Impedance mismatch and its effect on sound - Tube Amps.'

Yesterday at 12:20 PM

Inspired by a request. Read this: https://hughes-and-kettner.com/news/ohm-cooking/

• Simon Dorn
• Replies: 18
• Forum: Rig-Talk

• 

 

[shar-vell Dan]

Hmm an edited video to confuse people how quaint.

 

[Simon Dorn]

Hmm an edited video to confuse people how quaint.

There's no "edit" whatsoever. I played a Riff in the 8ohm setting and recorded it. Turned the Amp off. Changed the output selector. Recorded again. Turned the Amp off. Changed the output selector again. Done.

 

[Erock]

Here you go:

Thread 'Impedance mismatch and its effect on sound - Tube Amps.'

Yesterday at 12:20 PM

Inspired by a request. Read this: https://hughes-and-kettner.com/news/ohm-cooking/

• Simon Dorn
• Replies: 18
• Forum: Rig-Talk

• 

man, thanks for doing that. You can really hear the difference. I would still get sketched out mismatching with a tube amp though. There is so much contradicting information. I remember someone talking about flyback voltage a while back, going high to low, like 16ohm tap from the amp to a 4ohm cab. AI doesn't think it's a good idea either, lol. I'm just not comfortable enough to experiment with an expensive amp.

 

[Simon Dorn]

man, thanks for doing that. You can really hear the difference. I would still get sketched out mismatching with a tube amp though. There is so much contradicting information. I remember someone talking about flyback voltage a while back, going high to low, like 16ohm tap from the amp to a 4ohm cab. AI doesn't think it's a good idea either, lol. I'm just not comfortable enough to experiment with an expensive amp.

View attachment 379352

You're welcome! Regarding the Topic i quoted Larry in my other Post.