Tube pre-amps: turn off when not in use?

interesting question==i have both a tubed pre-amp and amp==i usually turn on my equipment about an hour before i sit down to listen== thanks doublel@mwt.net

I suppose, depending on the manufacuter, the standby mode may work differently to keep the amp/pre amp toasty?

here's a discussion of the "standby" mode on a BAT VK-30se preamp with input from Victor Khomenko of BAT. I'm pretty sure the VK-31se behaves the same way.

http://db.audioasylum.com/cgi/m.mpl?forum=tubes&n=86582&highlight=standby+vk&r=&session=

Physically, what is happening when the tube is in the standby mode? Is the filament heated, but no voltage on the plate? Are other components kept "warm" as well?

Sonofnorway is correct about the standby mode, this is your best option. Do not turn it off, but I would recommend you put it in standby mode.

As for tube costs, the last I checked (8-10 months ago) BAT was charging $200 per tube for what they called NOS 6H30's. FWIW, the price is not going down, only up. I believe BAT was charging $100 per NOS 6H30 about 2-3 years ago, now it's $200 per tube. They claim these are from the 80's, and better than current manufacturer 6H30's. BAT was also selling current 6H30's for $40 to $50 per tube, check with them as I'm not positive here. I remember the $200 price because I had a VK-51SE and the thought of $1600 to re-tube it with NOS 6H30's left a lasting impression.

If you go through other tube vendors instead of BAT you could find 6H30's for as little as $20 each. So to answer your question, no it wouldn't cost you $500-$1000 CDN per year (assuming you're leaving it on 24/7) to keep you preamp running, you could spend as little as $80 a year.
It all depends on how 'good' of tubes you want to put in it, and if you can hear the difference between a $20 tube and a $200 tube. If you get hooked on the NOS 6H30's and leaving the preamp on 24/7, it could get pricey.

I would recommend leaving it in standby, then replacing the tubes every 3-4 years wouldn't be much of an issue, even if choosing the NOS from BAT.

John

Never turn off tube devices. Think about it. You are heating a plate or plates. By turning it off and on you are causing the tube (and plates) to distort their shape each time. You gain many advantages if left on. One, it's "sound" is at a peak and ready for you at any time (versus waiting, for me, an hour). Two, you are not constantly forcing the tube to change the shape and size of all it's parts. (the heating and cooling cycle cause constant stress). Three, the tubes last much longer. I have an Audible Illusion 3A that is supposedly a "tube eater". Well, I've never had it kill a tube yet. I've had some in for years!

I've got a VK-31se. I leave it in standby mode when I'm not listening. I turn it completely off only rarely - when I'll be gone more than 2-3 days. My tubes are close to 3 years of use and still sounding fine. A set of four new Sovtek 6H30 tubes should be less than $100. I have not tried NOS.

Adamg, in my experience with 6922s in a DAC I was able to leave them on continuously for four straight years without excessive wear. When I owned a BAT VK3i its 6922s didn't seem to wear prematurely from being left on all the time. The complete opposite was true of my 6SN7 preamp which burned through expensive tubes if I left it on for too long. I am not familiar with the characteristics of the 6H30 which I believe your preamp uses.

Bsmith15, when I was hot and heavy into listening to my system, especially during colder parts of the year relative to LA, I'd do exactly what you do.

I was blissfully unaware of the cost of the tubes. It will cost me roughly $500-1,000/year (Canadian) to keep my pre running?

Since I get to listen mostly over the weekend, I turn on my pre on Friday evening and off Sunday evening. Minimizes tube loss.

for tube pre-amp-- its ok to turn off when not in use.
for solid state pre-amp-- its better to leave on all the time. These takes time to warm up.

I turn mine off when not in use. Have you seen the price of NOS 6H30's? At $200/pop, it'll cost you $800 to re-tube your VK-31SE with them.

I turn all my tube gear off when not in use. Tube gear gets warmed up pretty quickly, as compared to solid state, so there is less of a reason to leave the stuff on all the time.

All of my tube gear uses tube rectification, so the turn on is relatively gentle, and the life of the tubes is not being shortened by the turnon/turnoff cycle as much as would be the case with solid state rectification. I have not looked into use of thermistors to make the ramp up even more gentle, but if I did, there would be no doubt that turning the stuff off would greatly extend the life of the tubes.

I own 2 tubed pre-amps, which, in the past, I have left on continuosly. The tube life on both of these units used in this fashion is about 1 year. Now that I am using NOS tubes, I turn the pre-amps off when not in use.

Thanks for your replies. I do about 4-5 hours of listening a day so maybe switching off with use would be wise (or not?). For those who use tube pre with all-transistor based components (CDP, pwer amp), do you just turn off the tube pre while leaving all else powered up?

Tubes do wear out when left on. The output tubes on an amp may last something on the order of 1,500 to 2,000 hours or so. The smaller tubes used in preamps will last much longer. 5,000 to 10,000 hours and more is probably not unreasonable. (There are just shy of 9,000 hours in a year.) Some specialty tubes can last tens of thousands of hours, but your equipment probably doesn't have tubes of that nature.

So, the question is how often you want to replace tubes and also how much electricity you wish to use. Your personal listening style is also a factor. If you reliably don't listen after you go to bed and until you come home from work the next day, why waste tube life on the three-quarters of the day when you are sure you won't be listening? However, if you are always home and often listen at the spur of the moment at any hour of the day or night, it may well be worth it to you to leave the system on continuously.

Both my tube amp and pre amp have a standby mode (thank god) which keeps them pretty toasty. When I fire up my rig: 30 minutes to sonic blast off. Otherwise I would probably be talking about 2 hours...

I leave my ARC LS 25 on during the listening months (Oct-May) since I listen pretty much every day. Since this preamp (and yours too) uses the 6H30 tube the 10,000 hour life equates to around a once a year change. Not too bad a trade-off for the always warmed up sound. Of course turning off after every listening session will increase life, but not as much as you would think since the turn-on/warm up process is a little harder on the tube compared to continuous operation.

No matter what tubes will go faster turned on.. and preamps do draw a bit more than a dac or CD player and have more dangerous levels of heat in most cases.. Mine takes about 20 min tops to warm up and sound pretty much best after turning on.. this took about 100 hours of listening before it sounded that stable on new tubes however.. But short answer, turn it off, cause even if the tubes last for 4 years running 24-7, vs. only on for 2 hours 3 times a week will probably get you 10 to 20 years on the same tubes.

It could depend on the component and/or the manufacturer's recommendation.

When I owned a Kora Hermes DAC with two 6922 tubes I left it on coninuously for the four years I owned it without problem, even when fitted with NOS CCas, etc. But the tube preamps I've owned I always kept off when not in use.

The preamp I currently own uses two 6SN7 tubes and generates a decent amount of heat so I always turn it off. Plus the WWII era VT231s in that preamp won't last more than 6 months if left on all the time.