jhoak Posted March 16, 2011 Share Posted March 16, 2011 I really DO NOT want this to degenerate in to a debate about whether or or not tubes or any other electronic devises sound better or even different after XXX number of hours play. For the sake of my question lets all assume that there is merit to “breaking in” tubes for a number of hours / days. The question is... Do I need to have a signal running through them or is simply being “on” for 100 hours or so enough to facilitate break in? If they need signal is running the analog outs from my CD player set to "repeat" good enough? Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted March 16, 2011 Share Posted March 16, 2011 The unknown here is whether simply powering a tube causes changes which can result in a sonic difference, or whether it's the varying signal from your source which causes some kind of change. Also, one must consider the class of operation of the output tubes- if running class A, the tubes are going to be at their highest plate dissipation under zero signal conditions. This may not be a problem if they are not being pushed to the limits; but, if they are, tube longevity may be affected (particularly if the amp isn't adequately ventilated). Glad you started the thread as you did as I have some very definite opinions on this subject after 51 years in the field! Quote Link to comment Share on other sites More sharing options...
Guest " " Posted March 16, 2011 Share Posted March 16, 2011 The tube suppliers that have no returns for other than damaged on arrival have given me 20 hours as a common number. The tube suppliers that have an extended return policy have given me an excessive amount of hours. Quote Link to comment Share on other sites More sharing options...
jhoak Posted March 16, 2011 Author Share Posted March 16, 2011 For reference the question is about a pair of 6SN7s in a Grant Fidelity tube buffer. I had one of these previously and sold it in a moment of... well... I don't know what. It's currently running the "stock" generic Chinese tubes but I have a pair of Electro Harmonix gold pins and a pair of Tung Sols on the way to me. I guess the answer to the question (if there is one) determines how I roll the new tubes in. In the previous GF buffer I was NOT all that impressed with the sound through it using the stock tubes. I was able to secure a pair of NOS JAN 6SN7 tubes who's brand I don't recall at the moment but I think they were Philips. Anyway the difference between them and the stock tubes was startling. I have high hopes for the tubes that are en route to me. If I have to actually listen to them for 100+ hours that is NOT a problem for me. My system runs on average 5 hours every evening and between 20 and 30 hours every weekend. It will take me less than a month to compile more than 100 hours on whatever tubes I end up running. I'm just hoping to accelerate the process by leaving the buffer on 24X7 for a few days if possible. Quote Link to comment Share on other sites More sharing options...
LarryC Posted March 16, 2011 Share Posted March 16, 2011 If I have to actually listen to them for 100+ hours that is NOT a problem for me. The last new CAT preamp I bought was accompanied by Ken Steven's flat statement that it had to be broken in by playing music through it for 100 hours -- not just hiss or some colored noise.If it had a phono stage, he said to play music through the phono stage for 100 hours. He was right. Of course, that affected all the circuit components: tubes, wire, resistors, caps, etc., etc. Not only the tubes. Twenty hours sounds good to me. Quote Link to comment Share on other sites More sharing options...
Don Richard Posted March 17, 2011 Share Posted March 17, 2011 All vacuum tubes change throughout their life from the minute they are turned on until they burn out. A change in the bias point will adjust the circuitry so that the tube is operating in an optimal manner. Fixed bias designs cause the tube to be correctly biased at some point during it's aging cycle and slightly off at other times. This can certainly affect the sound quality, and the break in time will be different for different equipment. Quote Link to comment Share on other sites More sharing options...
ZAKO Posted March 17, 2011 Share Posted March 17, 2011 But some tweekers say you should CRYO freez a tube first,,, So where should you start ?????? Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted March 17, 2011 Share Posted March 17, 2011 All vacuum tubes change throughout their life from the minute they are turned on until they burn out. A change in the bias point will adjust the circuitry so that the tube is operating in an optimal manner. Fixed bias designs cause the tube to be correctly biased at some point during it's aging cycle and slightly off at other times. This can certainly affect the sound quality, and the break in time will be different for different equipment. Exactly! A tube's operating characteristics simply can't be predicted in advance, making a blanket "burn-in" time moot. And if a tube sounds best to you after, say, 100 hours use it doesn't mean that another tube from the same production lot is going to behave the same- it may sound best when first installed, never to sound that wonderful again. Even matched tubes in a push-pull circuit will age differently and cause variations in sound. The only way to truly maintain optimal sound quality is to measure the exact operating parameters at the time you believe that the sound just couldn't be any better, and recheck the parameters every 100 hours or so. Most amps cannot be adjusted so that all the operating parameters can be maintained at the desired level, so the issue of tube break-in becomes academic (imho). And in an all tube amp, since all the tubes are working synergistically, any variations in any of them will affect the ultimate sound. Apologies for taking this in the direction you wished to avoid (I would have said this in my original post, but didn't want to be the "bad guy")! Quote Link to comment Share on other sites More sharing options...
pauln Posted March 17, 2011 Share Posted March 17, 2011 I can tell you that in the guitar tube amp world, after installing and setting the bias for new tubes, most people will leave their amp powered on (not in standby mode) for a few hours to let the tubes operate hot and "get used to" that particular bias setting. Not sure what exactly might be going on there technically, but lots of techs and manufacturers recommend it to promote long term stable operation. Likewise when someone decides to change the bias of existing tubes; giving the tubes a few hours of hot running with the new operating point is thought to help the tube establish that new setting for the long term. Quote Link to comment Share on other sites More sharing options...
SuBXeRo Posted March 17, 2011 Share Posted March 17, 2011 not that i own a tube amp yet or have used one in the past but i look at things like this. I get a brand new CPU for my computer. I like to overclock the cores to make it faster but when you do this you increase the voltage and thusly the heat generated in the cpu itself. I always do a burn-in progrsam from a bit and normal usage for about a month. Some cores can be overclocked a tiny bit without adversely creating any extra heat but in order to really push it you have to have the core get used to heating timne and time again. At that you should overclock slowly when its a newer core. When i get a new car, you gotta let her run gently, sure she will perform if you want it too but its best to let it have some wear. Moral of what i am getting at is HEAT is a common factor. Heat will change the magnetics of metal when heated, it will soften materials etc. Tube amps i know will get hot, they need good ventilation and proper heatsinking. By having good device cooling you help to prolong the life of electronics, same with solid state amps. I would dare to say that the tubes at their normal operating temperature would sound different then when they first start off cold. I'd also dare to compare it to how a car runs when its first started up versus when its warmed up and has been running for a while. My theory on burn-in with electronics, any of them, even speaker wear in is that they are all electronics and will endure mechanical or electrical wear as they are used and age. As far as affecting performance and sound, again, not for this thread and another debate is on how they will sound. I will say though, the best thing you can do is use the electronics to have them endure wear-in. Eventually, we don't know when, the electronics will work at some sort of balanced equilibrium state, a state we hope is consistant for a long while before the performance degrades and the electronics eventually break and stop working. My final word is that they will work if you just stick the new tubes in and crank it. Will it be the best for them? Probably not but we dont know for sure. Based on other life trials of using things imporperly off the bat i like to err on the side of caution and work things slow. For most things in life slow and cautious is the safest way to go about things and generally yield the best results. Work em in slow, play music through them, make a playlist rully randomized with different music you like to listen to and let it play while your not home, id say increase the volume slowly as well. Make sure its vented well and caged (just in case). Quote Link to comment Share on other sites More sharing options...
Don Richard Posted March 17, 2011 Share Posted March 17, 2011 My final word is that they will work if you just stick the new tubes in and crank it. Will it be the best for them? Probably not but we dont know for sure. Based on other life trials of using things imporperly off the bat i like to err on the side of caution and work things slow. For most things in life slow and cautious is the safest way to go about things and generally yield the best results. Putting new tubes in a properly operating circuit and cranking the amp will not cause shorter tube life. There are no moving parts to "wear in" like in a car. The tubes will not explode. When installing new output tubes in a power amplifier with adjustable bias you will notice there is a period of time where the bias seems to drift. After a period of time the bias setting will stabilize, and this is the point where that amp is "broken in". For fixed bias types you will have to listen for the best sound. Quote Link to comment Share on other sites More sharing options...
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