Newbee - Thanks for your explanations and the advice about starting a new thread when interest starts to tail off. I thought I was still in time on 06/09, but when no responses came in for several days I should have started a new thread. |
After reading here and in a couple other threads about leaving small-signal tube gear on 24/7, I decided to write the manufacturer about my Wright Sound WLA12A. Here's what George Wright said:
Dear David,
I have worked in the support field for a number of years and serviced tube equipment that ran 24/7, we always had to change out tubes every 6 months because the cathodes would be used up. I suggest that once the equipment is baked in, about 50 hours, to turn off when not in use to saved tube life.
Best,
George
George has been around tubes a long time, so I, for one, would tend to give his opinions careful consideration.
I'll continue to turn mine off when not in use.
David |
Raquel, I enjoyed your comprehensive response, & 1 question, please. I suppose this 24x7-on approach would apply to my 2 Stax headphone amps? If there are any Stax owners out there, any thoughts? Thanks. |
Dougmc, FWIW I'll take a crack at your questions, but bear in mind these are observational answers, I'm not a 'techie'.
1) The circuitry of many pre-amps is not stable when first turned on. Because of this many pre-amps have an auto mute function which mutes the signal at the output until the pre-amp has stabilized. This is certainly true of most quality tube units. My DAC's and CDP's also have a short mute period as well. If your amp was powered up, and your pre amp doesn't have an auto or mute function, or the mute is inoperative, the output energy could cause damage to your amp if not protected (usually a problem with lower cost SS amps - higher cost amps typically incorporate protection circuits which shut down the amp if, for instance, DC is detected, and some also shut down the output section to protect your speakers from damage) and possibly your speakers.
2) Speaker thump is caused by a transient originating in either the source or the pre-amp at turn on, turn off, or both. Some times it can be caused by faulty switches, etc. Possibly caused by DC offset.
3) I'll take a pass on 'inactive', except to say that in my tube stuff it is accomplished by reducing voltage to the amplifying circuitry to a minimum, or eliminating it entirely. When you 'turn it on' all you are doing is restoring voltage to full value...the rest of the unit is warmed up and ready to go. Probably similar for SS stuff...I don't really know.
4) Don't know about the operation of your integrated, but if you simply pull the cord on a lot of tube stuff the auto mute function on the preamp will not be engaged, the amp will have sufficent stored power, and any electronic garbage from the sources or pre-amp normally experienced in shut down will be communicated to the amp and potentially to the speakers. Damage in that scenerio, though, is probably highly unlikely.
Your first question to Dragon - If the transients originate in the source using the VC will reduce or eliminate them from appearing at the pre-amp output
stage. However, if the problem is at the pre-amp's amplifing stage turning down the VC will have no effect as the VC usually preceeds the amplifing stage. There is nothing between the pre-amp amplifing stage and the amp input stage except for a mute circuit if you have one.
Regarding your musing in your secord paragraph...Amplifiers do just that, if they are not amplifing they should be dead quiet (or at least the residual noise floor should be minimal (usually this depends on the efficiency of your speakers). It is not uncommon for there to be a small 'pop' on turn on or off off a power amp. Not a big deal. I've never had an amp damage speakers from turning it on or off, but I've had a few pop's.
FWIW, you would probably get a lot better quality of answers if you were to start your own thread. As it is, no one who has not already participated in this thread is likely to sign on out of curiosity at this late date. In fact, some who already did participate may have assumed it had wound down (they had already contributed as much as they had to offer) and didn't review it again. I'm very prone to do this myself.
Hope that helps a bit........... |
Dougmc, FWIW I take a crack at your questions, but bear in mind these are observational answers, I'm not a 'techie'.
1) The circuitry of many pre-amps is not stable when first turned on. Because of this many pre-amps have an auto mute function which mutes the signal at the output until the pre-amp has stabilized. This is certainly true of most quality tube units. My DAC's and CDP's also have a short mute period as well. If your amp was powered up, and your pre amp doesn't have an auto or mute function, or the mute is inoperative, the output energy could cause damage to your amp if not protected (usually a problem with lower cost SS amps - higher cost amps typically incorportae protection circuits which shut down the amp if, for instance, DC is detected, and some also shut down the output section to protect your speakers from damage) and possibly your speakers.
2) Speaker thump is caused by a transient originating in either the source or the pre-amp at turn on, turn off, or both. Some times it can be caused by faulty switches, etc.
3) I'll take a pass on 'inactive', except to say that in my tube stuff it is accomplished by reducing voltage to the amplifying circuitry to a minimum, or eliminating it entirely. When you 'turn it on' all you are doing is restoring voltage to full value...the rest of the unit is warmed up and ready to go. Probably similar for SS stuff...I don't really know.
4) Don't know about the operation of your integrated, but if you simply pull the cord on a lot of tube stuff the auto mute function on the preamp will not be engaged, the amp will have sufficent stored power, and any electronic garbage from the sources or pre-amp normally experienced in shut down will be communicated to the amp and potentially to the speakers. Damage in that scenerio, though, is probably highly unlikely.
Your first question to Dragon - If the transients originate in the source using the VC will reduce or eliminate them from appearing at the pre-amp output
stage. However, if the problem is at the pre-amp's amplifing stage turning down the VC will have no effect as the VC usually preceeds the amplifing stage. There is nothing between the pre-amp amplifing stage and the amp input stage except for a mute circuit if you have one.
Regarding your musing in your secord paragraph...Amplifiers do just that, if they are not amplifing they should be dead quiet (or at least the residual noise floor should be minimal (usually this depends on the efficiency of your speakers). It is not uncommon for there to be a small 'pop' on turn on or off off a power amp. Not a big deal. I've never had an amp damage speakers from turning it on or off, but I've had a few pop's.
FWIW, you would probably get a lot better quality of answers if you were to start your own thread. As it is, no one who has not already participated in this thread is likely to sign on out of curiosity at this late date. In fact, some who already did participate may have assumed it had wound down (they had already contributed as much as they had to offer) and didn't review it again. I'm very prone to do this myself.
Hope that helps a bit........... |
Dragon1952 - Thanks for the information. One question. When you turned off your preamp before your amp, did you turn the volume control on the preamp down all the wasy before turning it off?
The instruction from Manley's manual implies that the harmful noise or transients originate in the preamp or the source. If an amp produced noise that endangers the speakers when the amp is turned on or off, the sequence in which the amp is turned on or off wouldn't matter because the amp feeds directly to the speakers. It's interesting that the component with the most amplification power poses the least danger to the speakers (or amp designers adquately address the problem).
Dragon1952 - In your second post, in explaining why you should have a source connected to a tube preamp, you analogized to the load placed on an amp by the speakers. However, the amp, not the source, is the load on the preamp. I'm not suggesting that both statements you made aren't true, just that the analogy seems off. |
Something else I've read is that you should always have a source connected to your tube preamp if the preamp is powered on. Same with a tube amp, that you should always have a load on the amp (speakers connected)if the amp in turned on. |
From a Manley preamp manual...
"7. Power up the preamplifier FIRST and allow it to settle for a minimum of 30 seconds before powering up your amplifiers. Turn off your preamplifier and source components LAST when powering down a system. This prevents amplification of turn-on transients and other noises when powering up or turning a system off and ultimately protects the speakers"
I'm new to tubes and got away with turning the preamp off first a few times. Then one time I heard this fluttering sound and then a pop. I powered the preamp back on and put on a CD and had no sound in one channel and a faint sound in the other. It turned out ,luckily, that I had blown 2 fuses in one channel of my amplifier and 1 fuse in the other channel.
You can do a Google search if you have a little time. That's how I found the Manley manual. It recommends, in another section, turn on sources first, then preamp...wait 30 secs, then amp and wait another minute or so before playing a source to give everything time to warm up a bit. Power off in opposite order. |
Doug.. I've checked each day hoping your questions were answered. I too would like to know. The only thing I could answer is yes to the 1st part of question 1.. Many of the "Sage" audiogoners have forgotten more about audio than I will ever know. I've learned a lot from these forums and greatly appreciate it.. I'm hoping the venerable Sean, Newbee or one of a host of others will explain. :) |
|
Great. I can ask some related questions without starting my own thread.
1. Many posts describe the correct order for turning on and turning off system components, but I have yet to see an explanation why. I’ve experienced “speaker thump” when turning off the electronics, so I guess avoiding that noise and its effect on the speakers is the reason for the order of turning off components (yes or no?), but what’s the reason for the order of turning them on?
2. What causes the “speaker thump”? Is it an electrical discharge by the capacitors?
3. What happens electrically when an amp or preamp is in standby mode? Since no sound is produced, I assume the signal from the upstream component is cut-off somehow. Is the entire circuit still activated by the electricity from the wall or do some parts need the signal to become activated (stay warm)?
With an integrated amp, the amp and preamp sections go off and on together. The integrated I used had a standby mode, but putting the amp in standby caused a small speaker thump, even with the volume turned all the way down. I never experimented to see what would happen if the wall plug was pulled with the unit on. Interestingly, the speaker sound was very slight if the amp was put in standby almost immediately after the music ended, but got louder when time elapsed before hitting the standby button.
Thanks for any answers. |
Classical1, 85db speakers are not a problem whatsoever for a tube amp with 80wt+ power. The biggest consideration is the impedence curve of the speakers. The flatter the better and the closer to 8 ohms the better. Higher efficency will open up options for amp designs though. FWIW, althought I'm sure your are factoring this into your choice for a SS amp, be sure that your SS amp has the proper imput impedence to match the output impedence of your preamp. A lot of SS amps have lowish imput impedence. Other than that there is no reason that a SS amp won't sound just fine. |
Not to stir the pot, but many people believe that tube gear using small signal tubes such as tube preamps and tube DAC's are best left on 24/7, this practice in fact lengthening tube life (and providing better sound). Quoting from the "TIPS & ADVICE" section of the owner's manual to my VAC Rennaisance 140/140 Mk. III tube amps:
"How long should tubes last? It has long been known in professional circles (and probably now forgotten) that a tube such as the 12AX7 will display BETTER performance characteristics after TWO YEARS of CONTINUAL operation than when it was new. In normal use it is not unusual for a low level tube to last 5 years or longer. Output tubes [i.e., power tubes used in tube power amps] are another story, as they are continuously providing significant amounts of current." (Emphasis original).
As for solid-state equipment, the most prevalent view (and I think the right view) is that running it 24/7 extends component life, and this, for the same reason that it is best to leave small signal tube gear on 24/7-- the heating up and cooling down that occurs as a result of turning a component on and off causes the internal componentry to expand and contract, compromising their physical integrity over time (it's basic physics). It is a settled point that leaving solid-state gear powered up improves the sound (many solid-state DAC's and solid-state power amps take two to four days to fully stablize). If you look through the threads with respect to solid-state equipment (and there must be 100 of them), there seems to be some consensus about these points.
As for tube gear and the threads, there are many, many people who report experiences that mirror mine (one thread in particular describes how an A-Gon member ran the infamous "tube-eating" Audible Illusions 3A preamp 24/7 for five years with the same set of tubes). I have had three tube preamps, a Jadis, a CAT and a Hovland, all of which I left on 24/7 (my CAT for three years straight), and I never lost a tube in any of them. Furthermore, they all sounded better with the "old tubes" than "fresher" tubes I substituted for comparison. I have an old Cal Audio Labs Sigma II DAC in my second system that I basically ran 24/7 for seven years and the original tube still sounds great. As for my tube amps, I tend to turn them on one or two nights a week during the week for after-work listening, and then on Saturday morning straight through to Sunday night to ensure top weekend performance and to keep the on/off (thermal) cycles to a minimum, this, as per the manufacturer's recommendation. Getting back to small signal tube gear (like tube preamps, tube DAC's, tube tuners, etc.), one of my dealers explains that, provided the component is left on 24/7, small signal tubes basically either die of "infant mortality" within the first 250 hours or so, or they last forever. The issue is probably moot anyway unless a person is using really expensive new-old-stock tubes, as it costs very little to retube a preamp or a DAC (rarely more than $100, and usually much less).
Of course, if one objects to leaving equipment on 24/7 for environmental reasons, that's another issue (those who do should probably buy mid-fi gear, as they are absolutely not getting the performance they paid for if they are running top-notch equipment cold). |
The deHavilland has @ a 30 second delay before it turns on. I've had no problems with the slight popping since using the above advice. Newbee, I think I'll go solid state when picking an amp, but I'm curious, since you have 'stirred' the pot. As I know little about tube amps, my assumption has always been that they match better with higher sensitivity speakers. Without breaking the bank can one use a tube amp successfully with monitors that have an 85db sensitivity rating? |
I'm on the lower end but am also incredibly pleased with my Wright Sound WLA12A and my modded Hafler DH-200. I leave the Hafler, my tuner, and my CD player on 24/7, and none generate any significant heat, nor do they draw very much power at idle. They are way more stable being left on all the time. The Wright Sound, however, gets turned off after every listening session. Since it's tube rectified, the turn on and off is very soft, and causes no thump or other noise in the system, even if I forget to mute. In this regard, it's way easier on my system than any of my SS preamps, and sounds great to boot! |
I switched on my amp from standby mode before my pre which is automatically muted for the 1st 60 seconds for the tubes to warm up. On powering down, I switched off the amp to standby mode and then the pre. So far, no noise,thump or pop..... |
Classical1
I also use a tubed pre CJ premier 16II with a ss amp CJ premier 350 and really enjoy the results. Excellent dynamics and control with much of the mid range benefits of a tube amp. Newbee has a point though tube amps are a beautiful thing once you get past the heat and maintenance issues.
Chuck |
Classical1, Not to stir the pot, but I can't resist piling on your 'new' discovery of the benefits of a tube pre amp (with which I totally agree!). Wait til you hear a tube amp.......:-) |
Chuck when not listening I have the amp in standby mode and have the tube pre turned off. I have a Naim CD and flat cap..Naim advised best results leaving it on. The Naim gear is very cool in idle. As a sidebar to all of this, I was always leary of tube gear. After 30 years of buying audio equipment I bought a deHavilland UltraVerve. Its the first tube preamp I've owned so I can't compare it to other tube equipment, but I can say it has made more of an improvement to my system than any other piece of equipment I've ever bought. I was not prepared for how nice a tube pre can match with a SS amp--I can't ever see going back. I hope to now go to a new SS amp (looking at Gamut, Pass .5 or Blue Circle) My monitors-Focus Audio FS688 are 85db, so I want to stay with a SS amp. Thank you again for your responses. |
Classical1
By leaving your amp on 24/7 do you mean in a stand-by mode when not listening to it? If not then my suggestion is that you should never leave an amplifier on 24/7 (tube or ss) it is dangerous as well as wasteful.
Chuck |
As my tube pre has no fuses, I was told by the builder to turn the pre on, wait while the tubes warm, and then turn on the SS power amp. Always with the volume on zero. To turn off, first the power amp, then the tube pre. Again, always with the volume on zero. I do turn them off if I am not going to listen to the system for a day or more. If I am going to listen seriously, I let them both warm up for at least 4 hours. Just my opinion. |
I got in the habit years ago of turning the level control all the way down, then I power down the amp(s), wait 10-15 seconds before I power down the preamp, then power down the sources. This is for tubed gear. For solid state gear, I leave it powered on. |
turn your amp off or on standby first then turn preamp off,visa versa,turn on your preamp first,wait a min. then turn your amp on,, |
Hpims, I think a lot of folks would disagree with you about turning off the SS. My equipment doesn't run hot when idle and most threads I've read say it's harder on the SS to turn it on and off, plus, at least to my ears it sounds a lot better being left on... and thanks Newbee for the advice. |
I just flip the on-off switch on the McIntosh C22. The MC275 amp is plugged into a Tripplite surge/noise reducer. It has a switch, too. All my stuff is plugged into it. I never leave any of it on....the ultimate surge protector!
Q: Why would you want to leave your amp on all the time? Heat is the enemy of solid state components. Makes them break down faster!! |
Best to put the amp in standby first and if your pre-amp has a mute function also the activate it as well. Belt and suspenders perhaps, but its free and should rule out absentmindedness. |
