robster Posted August 5, 2005 Share Posted August 5, 2005 Hiya, I plan on hooking up a speaker selector box to my VRD's after they arrive so I can run one pair of Forte's in the music room and when we want music in the den use a speaker selector such as a Parasound or Niles. I don't want to run all four speakers at the same time.Sometimes I like to turn up the volume in the music room and not disturb folks in the den where the other pair hooked up the amp will be. But I read on Audio Asylum that speaker selectors and switching can be dangerous for tube gear,is that true? Thanks, Robert Link to comment Share on other sites More sharing options...
pauln Posted August 5, 2005 Share Posted August 5, 2005 This is what I have always read about it: Solid state can stand a breif open speaker circuit but can be damaged by a short in the speaker circuit. Tube amps can usually stand a short but will not stand an open. I'm having trouble imagining the design for a switch that could prevent a momentary open without combining the two speakers for breif moment (maybe that's OK with no power applied?) The safest thing might be to power off the amps while the switch is changed. Be careful. Paul Link to comment Share on other sites More sharing options...
codhead Posted August 5, 2005 Share Posted August 5, 2005 If your tube amp uses feedback (if it's not a SET, it probably does), you don't want to run it without a load attached. If the selector uses make-before-break switching (or gives you the option of turning the 2nd set of speakers on, prior to turning the first set off), you should be okay. Link to comment Share on other sites More sharing options...
CaptnBob Posted August 5, 2005 Share Posted August 5, 2005 Some amps - the early Audio Research come to mind - had balanced outputs and floating grounds. A switcher with a common ground would cause trouble with them. I also imagine a dual mono amp or a pair of mono amps could fight too. Link to comment Share on other sites More sharing options...
robster Posted August 5, 2005 Author Share Posted August 5, 2005 Too much for my pea sized brain to handle. I put in an email to Craig and asked him if I could damage the VRD's using a speaker slector switch with tubes. Worse case scenerio,I will just keep a second system in the den w/the scott 233 and borrow money from my retirement account,rather than sell the Scott. The speaker selector that comes to mind is the Parasound at www.audioadvisor.com Thanks, Robert Link to comment Share on other sites More sharing options...
garymd Posted August 5, 2005 Share Posted August 5, 2005 No, but I'm using an amp selector switchbox with tubes. I just make sure I have the switch in the right position before I turn on the amp. Link to comment Share on other sites More sharing options...
hwatkins Posted August 5, 2005 Share Posted August 5, 2005 I am with Gary here - take a bit of care and all works - I have had my set up for 18 months and have yet to destroy anything of value.... Link to comment Share on other sites More sharing options...
scott0527 Posted August 5, 2005 Share Posted August 5, 2005 ---------------- On 8/5/2005 5:53:10 PM robster wrote: Too much for my pea sized brain to handle. I put in an email to Craig and asked him if I could damage the VRD's using a speaker slector switch with tubes. Worse case scenerio,I will just keep a second system in the den w/the scott 233 and borrow money from my retirement account,rather than sell the Scott. The speaker selector that comes to mind is the Parasound at www.audioadvisor.com Thanks, Robert ---------------- I've been running a Parasound speaker selector switch on my Mac MC240 for 3 years. No problems at all. Link to comment Share on other sites More sharing options...
robster Posted August 5, 2005 Author Share Posted August 5, 2005 Hey Scott,with the Parasound speaker switch do you switch between speaker pairs while the amp is powered on? Thanks, Robert Link to comment Share on other sites More sharing options...
scott0527 Posted August 5, 2005 Share Posted August 5, 2005 Well simply as a matter of caution, I always make sure at leat one of the 4 switches is on. It's not like when switching one pair "ON', the other one turns "Off". You turn them on an off individually. What you do need to be careful with is making sure you have their speaker protection switch turned on when you are playing more than two 8ohm pairs at the same time. As far as whether the amp is turned off or on, again, I don't worry about that, but I do make sure that at least one pair of speakers is always on. The manual for the parasound doesn't go into much detail but you can read it here: http://www.parasound.com/service_information/owners_manuals/pdfs/sps140om.pdf Link to comment Share on other sites More sharing options...
robster Posted August 5, 2005 Author Share Posted August 5, 2005 THanks,you have been very helpful. Cheers, Robert Link to comment Share on other sites More sharing options...
NOSValves Posted August 6, 2005 Share Posted August 6, 2005 ---------------- On 8/5/2005 5:33:39 PM mdeneen wrote: Rob---I can't for the life of me imagine how a speaker selector can be dangerous to a VRD amp. Of course, ask Craig to check, but hard to see what anyone is worried about. mdeneen---------------- I can't imagine a reason either. Tube amps are not as susceptible to open circuits as people try to say they are....... in fact the only real danger would be blasting music through them with no load for a extended period. Craig Link to comment Share on other sites More sharing options...
fini Posted August 6, 2005 Share Posted August 6, 2005 Kinda like peein' with your zipper up...Hey, Craig, how's Pop? Link to comment Share on other sites More sharing options...
robster Posted August 6, 2005 Author Share Posted August 6, 2005 Hey Scott0527 you have a PM Link to comment Share on other sites More sharing options...
mike stehr Posted August 6, 2005 Share Posted August 6, 2005 Don't those switchboxes have de-coupling caps on the switches? Link to comment Share on other sites More sharing options...
jbsl Posted August 6, 2005 Share Posted August 6, 2005 I have a Luxman system selector but not for speakers. I run my left and right channels from my Luxman preamp and my Denon A/V reciever into the selector and then run the out to my Cayin tube amp. I can hook up four preamps to it. It does have a ground connector on the back should I run a wire from it and where would be the best place to run the wire to? Craig I'm going to send a email about the caps. Xman Link to comment Share on other sites More sharing options...
djk Posted August 6, 2005 Share Posted August 6, 2005 Driving a tube amp without a load will cause damage to the output transformer. Depending on the circumstances, it could be destroyed in very short order. The mechanism involved is insulation breakdown from flyback voltages. If I was going to use a switch box with a tube amp, I would wire a 100 ohm 2W resistor directly across the outputs of the amplifier. In most cases this will be enough to prevent damage, yet not load the amp in any real way. Link to comment Share on other sites More sharing options...
robster Posted August 6, 2005 Author Share Posted August 6, 2005 Scottt I sent you another PM Thanks Scott 0527 for the very helpful info,I'm truely greatful to all! Cheers, Robert Link to comment Share on other sites More sharing options...
ben. Posted August 6, 2005 Share Posted August 6, 2005 ---------------- On 8/6/2005 3:56:08 PM djk wrote: Driving a tube amp without a load will cause damage to the output transformer. Depending on the circumstances, it could be destroyed in very short order. The mechanism involved is insulation breakdown from flyback voltages. If I was going to use a switch box with a tube amp, I would wire a 100 ohm 2W resistor directly across the outputs of the amplifier. In most cases this will be enough to prevent damage, yet not load the amp in any real way. ---------------- Do you have any reference material to point to regarding the flyback voltages and transformer failure? I've been told that running tube amps at marginally higher loads is critcally dangerous, and I'm looking to learn more about why (or why not) this is generally true. (we're talking about a nominal 8 ohm load vs. a 4 ohm load on a bass guitar amp...) Thanks. Link to comment Share on other sites More sharing options...
AGH Posted August 7, 2005 Share Posted August 7, 2005 . Link to comment Share on other sites More sharing options...
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