Post your completed projects


Streets still works -

That timer is awesome! Thanks for sharing the parts list and pictures of the final product. I’m pretty tempted to build myself one…4_gif

Darren Myers said That timer is awesome! Thanks for sharing the parts list and pictures of the final product. I'm pretty tempted to build myself one....4_gif

Thanks, I couldn’t convince Paul to put in a tube hour meter for the BHK amps, so this was the solution. The case is a bit of a jury-rig, and the packaging is tight with all the wires, but it fit and is secure once it’s all put together. Getting it there was a bit of a challenge, but it’s running fine.

wglenn said

All the careful planning and execution still cannot stop an idiot from drilling a nice hole in the wrong spot.boxing_gif In wood working I have learned to fix my mistakes. In metal I just live with them. If anyone ever asks, I’ll just tell them it is a resonant tuning vent!4_gif

This is the back plate for an amp? How far along are you on this project?


Done. This was my NCore amp… with resonant tuning port…

Streets Still Works said Switch:




Meter data sheet:

Violet wire connected to ground (puts unit in trip mode so it can be reset)

Brown wire connected to ground (displays tenths of hours)

Green wire connected to ground (blanks leading zeroes)

Yellow wire N/C (it’s an output that’s not used)

Blue wire connected to switch, other side of switch goes to ground to reset counter once button is pressed

Red wire connects to all jack center pins (V+)

Black wire connects to all jack outer pins (GND)

Drill hole for meter in case, and I used a Dremel to cut out the holes for the jacks and the pushbutton on both sides of the case. Pushbutton mounted flush so you can’t accidentally reset it. It all assembles via one screw in the back of the case.

The counter powers on when the 12VDC trigger goes active and counts as long as there’s voltage. Once the trigger goes off, the counter stops ad goes blank but records the last known value and continues the count when the voltage is reapplied.

EDIT: I missed one wire, the orange needs to be tied to V+ to count cumulatively and not reset when power is removed.

I really think you could make a single output unit that could be sold. Besides Audio Research does any other tube amps or preamps come with built in timers?

If I was capable of building these, I would consider patenting the design. When I say “I”, what I mean is you. If you could build these and retail them for around $50, you could sell a lot of them. Getting the parts wholesale, I would think it could be done.

Going off the trigger is such a simple, elegant solution.

I really think these would sell great through Music Direct and Audio Advisor.


Many years ago I had some design projects with my gear you can see below as a comparison of old to new design.
You might be surprised how an Accuphase CD Player can look. And you might see, that I borrowed the style of design for the amp from Gryphon. It was quite some work getting all this from the idea to reality with different stages of various workshops for each step.
Long ago and it all changed, but this amp proved “life’s too short for small amps”

Streets Still Works said On a different note, here is a tube hour meter that runs off the DC trigger. This keeps track of the hours on the BHK amp.....
Is it correct that a tube hour meter does the same thing as if you stick a small digital timer adding time slots aside the preamp and hit start/stop every time you do it with the pre? Is it to avoid not hearing a slowly coming loss of quality from the pre?

I ask because so far I thought tube death comes audibly and suddenly. But as I have military grade NOS tubes lasting quite long, I have no experience yet.

jazznut said I ask because so far I thought tube death comes audibly and suddenly.
Unlike incandescent light bulbs, tubes die slowly and quietly - like the proverbial frog in a pot of slowly heated water.

The best way to know if you have an issue is to buy to identical sets of tubes and occasionally swap out the used ones for unused to compare.If the used ones sound soft and unfocused and/or weak in comparison you know they are getting tired.


Ok thanks ELK, so in case an hour meter should help, one had to know the expected hours of certain tubes and they have to die slowly not in a different time range than expected if I’m right. Still seems unsure to rely on to me. But certainly it helps to change tubes a little earlier than their expected life cycle. I’d do it by roughly calculating how many hours I’m listening in average each week. Shouldn’t be much less exact at the end.


As with many things audiophile, we tend to worry and obsess too much. :slight_smile: Small signal tubes are perfectly healthy for thousands of hours. Even power tubes last a long time (The 300B is rated for over 10,000 hours).

If I used an hour meter for signal tubes, I would check them perhaps every 2,000 hours - good two+ years of use for most of us.