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Can a tube amp be damaged by a speaker switch?

Help please from the tech crowd.

I had a room with two systems....one for audio and one for TV. The audio is a Leben tube amp into Altec Valencia speakers. The TV is a Marantz receiver into a group of five budget small speakers. My goal was to use just the Valencia's for both amps because the big Altec's are so much easier to hear dialogue on the tv. I also want to clear up wire clutter in a cramped cabinet. 

My solution was a Luxman AS-55 speaker switch which a very high quality unit designed to allow 3 speakers and one amp, or in reverse setup, three amps and one set of speakers. During set up, I had a question and called the Luxman US manager who picked up the call and was so gracious with his expertise. Great service. The problem is after hearing my questions he said..." we do not recommend using a switch with a tube amp as running tubes without a load can damage the amp...even break it. 

I can use the switch if the the tube amp is turned on only when running into the speakers. The problem with that is the Leben really needs a good half hour to warm up and I would like to do that while watching tv. It will make it cumbersome to switch back and forth between the two. 

Eliminating the Luxman AS-55 switch and just using two sets of speaker wires is an option, but I really do not want to have to plug and unplug the bananas on my Audience cables as that can only hurt them and its a hassle. Im also worried about potential damage to the Altec's with two amps hooked up. 

My question is for the experienced tube users. How much risk am I running if I use the Luxman switch as I intended? Can it really damage the amp or is the Luxman rep exageratting the risk for laibility reasons. What is the potential damage?

 

128x128tamarack4
elliottbnewcombjr
5,461 posts
 

as budjoe mentioned, and why he asked for your system specifics:

Front Pre-outs is a definite solution, some receivers have pre-outs, but not Front Pre-Outs, some do, it’s an important feature.

IF Front Pre-Outs: you would be using your Marantz to power center and surround speakers only, and the front pre-out would go to your Leben Tube amp, which would ALWAYS power the front speakers, music or video.

The Marantz would control the volume of all, including the volume of the front pre-out, and any settings you change in the Marantz would be passed to the front pre-out.

NEXT: We need to know the model # of your Leben, and if not an Integrated, any pre-amp in-line, and it would be good to know what other 2 channel sources you use the Leben for.

Modern preamps have HT bypass, simply a selectable preamp input (for Video) that bypasses the pre-amp’s volume control (so Marantz can control the volume along with the other speakers the Marantz is powering.

Older equipment, no HT Bypass: knowing it’s specifics, a solution can be found.

 

retroactiv
31 posts
 

I use a tube amp and a solid state amp and share one pair of speakers with them. I am using a Solupeak P3 switcher. I've been using it for a while now with no issues. I just make sure I am extra careful to make sure the switcher is set for tube amp before powering on my tube amp and making sure the other amp is off. One time I powered on my tube amp without switching the switcher to it (so no load) but then powered off the tube amp right after since I forgot to switch the switcher. It didn't cause any issue, but maybe I got lucky. Realize this is a risky setup with my expensive tube amp. But the convenience is great. I also always have the volume knob all the way down when turning on tube amp and never have any source playing.

tony1954's avatar
tony1954
1,049 posts
 

Why don't you just get a proper centre channel speaker?

In a 5.1 HT system the fronts don't carry the dialogue anyway.

clustrocasual
101 posts
 

@imhififan I actually have a Leben and during the course of modding it, one night I accidentally left the dummy load off and ran pink noise. Next morning..I freaked out...yet, no problem with it at all.

​​​​​​​I know there are vintage guitar amps that have blown up from not having a load, and I dont know the technical reason, but it doesn't always cause problems.

larryi
4,024 posts
 

We are warned about the practice, and it is good advice not to do it, but I have not heard of actual failure.

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