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Amp switcher with tube amp protection

Hi there, I'm a bit of a beginner, so stick with me please :)

I'm looking into buying a tube amp (muzishare X7), but would prefer to also keep my solid state amp for movies and tv so I don't waste away the tubes on unimportant stuff :) Would prefer to use just 1 set of speakers as i got rid of my surround setup and settled for some Klipsch rp600m.
I'm looking for a amp switch that will protect the tube amp from not being hooked up to speakers. I know i can turn it off, then switch. But I'm sure I will one day make a mistake there.
I did stumble upon a thread here about somebody building his own switch. But are there commercial options out there? Because I couldn't find any.. or maybe I'm searching with the wrong search terms.. 
Also preferably not too expansive as my setup would be quite low end in terms of audiophile gear...

Hope someone can point me in the right direction!
BestMartijn
mw000
imhififan's avatar
imhififan
2,181 posts
 
The most simple way to protect your tube amplifier output transformer is connect a 5Watt 100Ω - 150Ω resistor across the "+" and "-" speaker output binding posts of your tube amp, either 4Ω or 8Ω tap is OK, it will provide some load to the tube amp when the speaker is disconnected. 

https://rukminim1.flixcart.com/image/416/416/kgfg2vk0/resistor/j/v/r/100-ohm-5w-wire-wound-resistors... 

There also a switcher with built in loading resistors:

https://www.amazon.com/Amplifier-Receiver-Speakers-Selector-Switcher/dp/B0796KGVXT
pauly
1,012 posts
 
You need to consider your music listening vs. tv watching patterns. Tubes will last a lot longer if left on for slightly longer periods than frequent power ups and power downs. 

If you listen to music 2 or more times a day, broken up with a period of watching tv in between, your tubes will be better off staying fired up. 

I’m in the same position as you - I use the same area for movies and music. I fire my amps up at around 9am every morning and they stay on til 1 or 2 am the next morning. I use the tube amps for both music and movies. I have done that for many years - no problems. I have not used up a power tube yet. 


mw000 OP
4 posts
 
Also interesting to think about, the amount of music vs. tv usage, and limiting turning the amp on and off.
During the week I typically use my system for a couple of hours of tv each night. During the weekend a mix of music and tv.
So I guess in my case solid state during the week, tubes for the weekend.

In terms of the Specialty-AV SP-71, any idea if the resistors have an effect on your sound? Or do they only get "activated" when you switch to the other amp?
imhififan's avatar
imhififan
2,181 posts
 
In terms of the Specialty-AV SP-71, any idea if the resistors have an effect on your sound? Or do they only get "activated" when you switch to the other amp?
https://forums.audioholics.com/forums/attachments/20190218_165752_zps9eahesvq-jpg.28295/

Four resistors connected to both inputs, so it is "activated" to both amplifier at all times.
Those resistors consume less than 1/10 of the amplifier output power, IF you want to switch amplifiers in your system, this is the necessarily compromise, but I doubt you can hear the effect.
BTW, solid-state amplifiers usually are safe to stay on without load, you can disconnect those resistors on the AVR side.


mw000 OP
4 posts
 
Thanks for all the info everyone! This switch seems to be the easiest option in my case.

As i have never went above 40% of my current amp's volume (35watt) I also doubt I will mis that 10% of output power. The tube amp will have 25/45 watt output power. So should also be totally fine.

Cheers!
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