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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, 

the 12v trigger could possibly work, and would be a perfect way to activate such a device. My amps unfortunately do not have 12v triggers :-(
so in my case, I will have to use a household plug and connect the hour counter to my power conditioner.

if you (or anyone else with 12v triggers on their gear) are interested in one of my yet to be built devices, I will do the appropriate research on the actual function of the 12v trigger and consider making a 2nd version, or enhanced functionality in one design to accommodate more users. I should be able to create a version that can be activated by the influx of current when I turn on the power conditioner that it is plugged into, and also have an option to activate it via 12v trigger.  I think that addition will not add too much complexity...
peter_s
1,335 posts
 
 It is worth checking out. In my case,  although produced by the same manufacturer, my amplifiers have 12 V triggers but my preamp does not. I'm assuming that the 12 the trigger on an amplifier only received instructions and does not send them. So I am not sure how it  would send information about on/off status.
I am guessing that most people would not want to have to plug their amplifier into some other device in order to achieve the time accounting.  That is why I was suggesting a temperature sensor. But a 12 V trigger could also do this job. 
marktomaras OP
544 posts
 
Peter,

what amplifiers do you have?  I am researching the possibilities of a design that would employ a toggle switch that would allow one to choose a mode where the simple connection to the electricity will activate the hour counter, as will be useful in my case.  Flip the toggle, and the alternate mode will be selected where the 12v trigger will activate the counter.

Here is a rough preliminary sketch that I made of the device.  There are 2 LEDs to indicate the mode of operation.

can you please tell me the model numbers on your amp and preamp so I can use them as a research starting point?  

thanks!
peter_s
1,335 posts
 
Mark - my amplifiers are VAC Phi 200's.  I'm actually surprised that they have 12v triggers given the current rush I sense when I turn the beefy switches on! I'm actually also surprised that my preamp, a VAC Signature Mk 2a Signature SE preamp does not have a 12v trigger (one would think it would pair with the amps!).  You could call VAC (they are very helpful), though I doubt that the trigger input to the amplifier sends out a signal when the amps are turned on/off.  I don't know much about that since I've never used it. I could imagine that your device, if it passes the trigger pulse through it, could be used to count hours. I will keep my eyes open for further posts...
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?



 
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