Millett "Starving Student" hybrid amp
Oct 11, 2013 at 12:50 PM Post #6,663 of 7,277
  I was listening to my MHSS at work and I realized I never did post any pictures of the finished amp...its dead quiet and sounds pretty darn good...
 
 
 
 
 
 


IF you are willing to build and sell those
 

 
Oct 11, 2013 at 4:36 PM Post #6,664 of 7,277
  I was listening to my MHSS at work and I realized I never did post any pictures of the finished amp...its dead quiet and sounds pretty darn good...
 
 

 
That's a fantastic build vixr! Congratulations! I can only imagine what the other people at your wokrplace thought when you brought it in!  Which tubes did you use in your build?
 
cheers!
 
Oct 11, 2013 at 7:17 PM Post #6,665 of 7,277
   
That's a fantastic build vixr! Congratulations! I can only imagine what the other people at your wokrplace thought when you brought it in!  Which tubes did you use in your build?
 
cheers!

The folks at work are used to my unusual amps, but this one got some curious looks...we are in a low static, clean lab, so visitors are pretty rare.
I am swapping between some NOS 12AU7 RCAs and some used 12AU7 Mullards I got from a British guy on ebay...the Mullards sound fabulous but the RCAs have a bit more gain...
 
Oct 11, 2013 at 10:06 PM Post #6,667 of 7,277
Beautiful work as you've always done in the past, Vixr!!  This one may have outdone all the others, though.  It's a long way from a Millett Hybrid in a lunch box (which I thought was great)!  Simply fantastic!!
 
Oct 12, 2013 at 9:33 AM Post #6,669 of 7,277
  Thank you for the kind comment, it probably will be for sale in the future.

Oh dang I'd better start saving up now >.> so what are the power specs! 
 
Nov 17, 2013 at 11:00 PM Post #6,670 of 7,277
Well friends, I'm a long time lurker of the forum, first time tinkerer, first time poster here.
I decided I was going to see if I could build a SSH amp and it turns out I cannot.
When I turn her on she makes a quick chirp and nothing else. No smoke or flaming balls of fire but also, no glow from the tubes, no sound.

 
Any diagnostic help you could provide would be much appreciated.  I think I'm a little depressed about the whole thing and the time I've put into it so far.
Thanks!
 
Nov 17, 2013 at 11:23 PM Post #6,671 of 7,277
I built a MHSS in a similar aluminum enclosure...I found that the kapton film in the isolator kits was too thin and the back of the transistors was able to bite through it and short. The aluminum was just rough enough to have some high spots...remove the isolator film and see if they dont have holes in them. Although, I must say your enclosure looks a bit smoother than mine.
 
Nov 17, 2013 at 11:41 PM Post #6,672 of 7,277
Thanks for the speedy reply! I pulled the the isolator kits off and they seemed to look okay, I did a quick power on/off with them 'floating' and the result is the same as before. I probably should mention I am attempting to do the 12au7 with most of the equalizer mods.
 
Edit:
One thing I don't understand is the middle mosfet pin AKA pin 3, is wired to the bridge of tube pins 4/5 AKA the heaters, which are then connected to ground, so doesnt that mean the mosfet is grounded?
 
It appears I had my 48v line from the on/off switch attached to the right most pin, not the center pin. I made the switch back and tossed in a tube to test things out. My c1 cap on one side Git extremely hot in the matter of a few seconds and my heater glowed way too brightly. The heater thing tells me I have too much voltage on the heater like but the hot cap I don't get.
 
Nov 19, 2013 at 11:06 AM Post #6,673 of 7,277
After tinkering around with my multimeter, I was able to correct the ground short, but my voltages seem to be all different than what others have posted on this thread.  Both channels of tube heaters glow brightly, and my C1 Cap heats up dangerously and quickly.  (Not C6, just C1 so it is isolated to one channel) Does anyone have a clear photo of a PCB that might help me see where I have gone wrong? I think I may be misinterpreting some part of the wiring diagram.
 
Nov 20, 2013 at 8:40 PM Post #6,674 of 7,277
After tinkering around with my multimeter, I was able to correct the ground short, but my voltages seem to be all different than what others have posted on this thread.  Both channels of tube heaters glow brightly, and my C1 Cap heats up dangerously and quickly.  (Not C6, just C1 so it is isolated to one channel) Does anyone have a clear photo of a PCB that might help me see where I have gone wrong? I think I may be misinterpreting some part of the wiring diagram.


C1 is a decoupling capacitor for the power line. If we are talking about the same relative part numbers, it's tied to ground on one end and R13 and the power line on the other.

Please double check the voltage rating for that cap, as well as the voltage output of your power supply.

Cheers!
 
Nov 20, 2013 at 8:58 PM Post #6,675 of 7,277
With the power switch in the off position:
PSU---+48.6---DC Pin--+48.6--SW----------+C1-----------Ground
                                             |
                              ...Drain----------R13-------....
 
When I hit the switch:
PSU---(-22)---DC Pin--(-22)--SW----------+C1-----------Ground
                                         |
                          ...Drain----------R13-------...
 
Both tubes glowing very brightly. This is super wrong.
 

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