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Would anyone like a tube hour counter for amps that don't have this function ?

I am planning and designing a small,  attractive,  external tube hour counter,  and I would like to get a sense if anyone is interested in this for themselves. If so I may be compelled to make a batch of these at the same time Rather than just one.

 I have an audio research VT100 mkII and and LS25. I really like these amplifiers, but neither of them have a way of tracking tube hours. I know I can just listen to the tubes to determine shortcomings, but I'm also an analytical sort of guy, so having an accurate tube hour count would be useful to me.

my plan is to use a digital, non-resettable, industrial hour counter.  I am planning to recess this into a small aluminum enclosure with professionally machined openings for the  Digital counter as well as the power cable coming out of the back. The plan is to use a  Black anodized aluminum body with natural aluminum face plate and rear plate. A power cable coming  out the back and be terminated to a standard household grounded plug. There will be rubber deer on the bottom. The device will be small: perhaps about 4 inches wide, 2 inches tall, and 4 inches deep.

 I have a six outlet power conditioner with one outlet free. To use this hour counter, I will plug it into my conditioner, I will switch off the power on the conditioner when I'm not using the amplifiers.  When I switch on the Power conditioner and subsequently the amplifiers, The hour counter  Will begin its count. 

 For those of you who plug their power amplifier directly into the wall, I suspect that many of you will still plug your preamplifier or other components into a conditioner or strip of some sort. In that case this tube hour counter will still work for you,  unless you just turn on your power amp from time to time for fun! 

 Since I will be re-tubing my power amp soon,  this is a perfect time for me to add this to my system.  I plan to use my small label making machine (brother p-touch style) to put a label on the bottom of the aluminum enclosure that has notes on the install date, tubes, and hour counter numbers. 

For example,  I may just change the power tubes on my amplifier and not touch the signal or driver tubes in the power amp, or the preamp tubes in the preamplifier at this time. When I go to change those smaller tubes in the future, I will notate that change and log the hour count in a  small note on the Label Maker,  and stick it to the bottom of the enclosure.  The hour counter will be non-resettable to avoid tampering or mistakes.

I'm not yet sure about the price of something like this, I'm doing the research now. Since it has to sit on my audio shelf, I don't want it to look like a piece of junk or a children's science project. Because of that, I will use professionally sourced parts, quality machining, and thoughtful design,  planning,  and careful assembly. 

 I suspect the final selling price may be in the neighborhood of $100 - $200. But that's just a wild guess at this point. If anyone's interested please let me know and I will consider  making several of these instead of just one for me! 

Take care,
Mark
marktomaras
marktomaras OP
544 posts
 
Peter, it's been a very interesting research process. I am looking back into a temperature sensor as a triggering option for my hour counter device.  I think if I could eliminate human error, and make the device fully automatic, this will be the best option. I am making progress!

I am also now looking to eliminate household voltage levels and design a more sophisticated device that will employ a circuit board and hopefully a battery for operation. We shall see.

i have a question for you about your vac phi 200 amps.  Obviously the  tubes get hot, but do the there large boxes on the back also get hot? I suppose these are the power supply and the output transformers.  I ask because if my device were to have an external temperature probe, be it a small wire or thin steel probe, I would need to devise a non-invasive, reliable, and not completely unattractive way to place and keep the probe in the heat of the amp.  

With my amp design style, I could attatch the probe end to the top of the amplifier case cover, and it would be just above the tubes, right in the heat.  With your amp style it may be possible to slip the probe, if it is thin enough, between the power supply and one of the output transformers - if they also produce enough heat.

what are your thoughts on this?



 
peter_s
1,336 posts
 
Hi Mark. I think a temperature sensor would be most flexible, and optimally something on a thin wire that could be placed near the base of a power tube or on a transformer (mine do get hot).  I was looking into making something like this for a totally different purpose but the design was too techie for what you are trying to accomplish (e.g. temperature probe, raspberry pi computer as a datalogger). I wonder whether an IR termperature sensor would work as well...
marktomaras OP
544 posts
 
 I'm getting closer. I'm looking for a point-to-point wiring solution with low voltage components and avoiding  a circuitboard.  More info to come!
ediver
29 posts
 
Interested. Why not a small microcontroller with an LED display, that is resettable? You could do a current sensing "tap", so you know when that device under test is on; no need for a thermistor or to plug in to the power conditioner.  With battery backup. :-) 
russ751
38 posts
 
I have had tube equipment for more than 15 years. My first tube amps were a pair of Antique Sound Lab Hurricanes.  Very cheaply built but they sounded great. After about 8 years I began to have a lot of crackling in one amp.  Customer support was excellent. They instructed me to clean the tube sockets and pins. I did and the problem was solved. My point is that before going through the expense of replacing tubes try the cheap solution:  clean the pins and sockets.
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