2. amps-preamps
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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
 
Ediver, what an excellent suggestion!

are you referring to a device similar to this:
http://www.ekmmetering.com/split-core-ct-200a-200a-26-6ma-13mm-0-51-hole-diameter-sct-013-200.html

Do do you think there is any possibility of introducing any negative effects to the AC (think crazy audiophiles here) with a current sensor clamped around someone's AC cable?  Or do you think this will be fully invasive?

I was researching peter's temperature suggestion, and it still holds water, but sensing the current sounds even better. Perhaps I can design a simpler and cheaper device this way.  also, the temp probe was always looking to be an issue. How do you ensure it stays in place, etc.  the current sensor clips to the power cable, seems like a great way to go.

I am sure I can hack this thing together, but I actually want to design a thoughtful, attractive, high quality device at a reasonable cost. We shall see if anyone buys one, but I will be the first customer :-)

russ - agreed, replacing tubes is not the only answer, but I do feel that knowing how many hours one has on their tubes is useful data...

dark matters, indeed, I have been looking at the full gamut of hour counters from $5 cheapie all the way to $100 fancy ones. I found some in the $20 range that look quite good.

thanks for the input everyone! Please share any more ideas, they have all been inspiring!
peter_s
1,336 posts
 

The question is how to get the split core current sensor to communicate with the hours counter.  I am unclear about what kid of signal the hours counter requires, and whether the current sensor would provide this signal or if there would need to be some sort of "translator" in between.  Thoughts on that?

If you make a reasonable looking device (not aluminum billet), I think this is an accessory you could sell online and perhaps through online companies (e.g. music direct).  Personally, I don't require anything fancy looking, just reliable.  I think most people would tuck it out of the way and only look at it from time to time to see how many hours they are putting on their tubes.

twoch
429 posts
 
Get SS. You're worried about tubes lasting 4,000
To 5,000 hr.s.   with all due respect of course
marktomaras OP
544 posts
 
Peter,  I am in the process of hiring an engineer to help me sort out the electronics specifics.  If I can get this thing to run on batteries, and have it last for years on a 9V or Lithium battery, that would be killer.  We shall see.  I have also looked into relays and switches that can possibly interface with the current sensor.

I made a mock up of how I may design it.  It is early days yet, but I love design, so here is my first real go at a product!  It has a rectangular blue LED that will illuminate when the current is sensing, and the hour timer is counting.

Link to my mock up:  http://www.marktomaras.com/4485090-tube#0

Twoch - I'm not worried.  I just like the idea of knowing how many hours are on my tubes.  I have a lot of respect for high end solid state, but I love my tubes :-)

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