[Ikarios]

Quote:

I don't think your description works, even for a switch.  You might be thinking about the power rating for resistors - then what you've described is OK, because you're looking at the product (power) of 1A * 5V = 2A * 2.5V.
 
As for specific ratings for current and voltage, voltage has specific requirements - especially when considering switches and connectors, because underatings could result in arcing or fusing the contacts over time. 
 

Okay, looks like you are right.
http://www.head-fi.org/t/319231/millett-starving-student-hybrid-amp/5370#post_6791173
That was the question I was thinking of. Voltage limits due to the possibility of arcing makes sense.
 
 

 

[the_equalizer]

Quote:

Would there be a problem if I used an IRF530 instead of an IRF510? I can get the former locally, and for much cheaper than mouser.

From looking at their respective datasheets, I'd say an IRF530 would work OK...  I can't guarantee it, though
 
cheers!

 

[davidvanderbilt]

I have been searching on the pages in this thread. Can someone tell me what schematic/instructions I can use to build this amp. I am extremely confused, because a few threads i read said that the original tubes and PCB board are very scarce. What can I do, or how are people currently building this amp? Thanks!

 

[Beftus]

You build the 12au7 version of the amp. Start reading here: http://www.head-fi.org/t/319231/millett-starving-student-hybrid-amp/3870#post_6024902
 
Schematic: http://diyforums.org/SSMH/variants/SSMH-12AU7.gif

 

[ericj]

Quote:

I have been searching on the pages in this thread. Can someone tell me what schematic/instructions I can use to build this amp. I am extremely confused, because a few threads i read said that the original tubes and PCB board are very scarce. What can I do, or how are people currently building this amp? Thanks!

PCB? This is an amp to be built point-to-point!
 

 

[videoman5]

I found my enclosure at a garage sale:
 

 
The pot will be connected to the turn dial, and the heatsinks and tubes will free float in the bubble. The PCB and other crap will be held in an empty space in the bottom part. The power and input will be mounted on the back, and the output will be in the gumball dispenser part. I've got almost all the parts together; I just need the PSU, tubes, and sockets. I am not too worried about the MOSFETs getting too hot, as they are rated up to 175C, which they won't reach. I also want to mount something in the quarter part. I am thinking about using a Devo button I have. Pretty excited about this.

 

[SpringHalo]

Another friend of mine is giving me some sockets and a pot, but also has two 250uf capacitors that I might be able to use as substitutes for C7/C8. The BOM says it's to increase plate resistance, but also needs a good cap. Would I be better off without it, or will a 250uf cap work?
 
Just to be sure, the pot can be anywhere from ~10ohms to 200ohms, right? It just changes the sensitivity of the volume?
 
Thanks
 
EDIT: I have a socket and two 12AT7 tubes, and am thinking of getting two orange tube LEDs to light up the tube better. First of all, is 320mcd enough, and second of all, can I test out the tube heaters to see how much light they give off by simply attaching 12V (@1.2A) to the heater pins?
 
Editv2: Tested the tube heaters today with a 12v constant power source. The heaters are mostly covered, so there isn't as much glow as I would have hoped. LEDs are a must now.

 

[jacobthellamer]

 
Just built the amp with Fujitsu 19R-P11 pentodes(wired as triodes) and a custom 48V power supply.
 
There is a local electronics store clearing out their tube stock so I picked out 6 of these particular tubes hoping that they would work from the specs. I will be back for more as soon as pay day hits now that I know these work
 
The 19R-P11 has a heater voltage of 19V too and a heater current of .2amps and seems to work fine without modifying the circuit.
 
This thing really makes my grubdac shine
 
I still need to get a case sorted and need to repaint the heatsink as it got a little scratched drilling out holes for the tubes.
 
Here is everything together for testing:


 
Pin out equivalent for the 19j6 if anyone else wants to try:

 

[videoman5]

I have some insanely large caps I can use. Would it be safe to use .3F caps for the power caps?

 

[Beftus]

 
Quote:

I have some insanely large caps I can use. Would it be safe to use .3F caps for the power caps?

A complete waste of capacitance IMO. Perhaps you could use them to make a flux capacitor... 

 

[the_equalizer]

 
Quote:

 
Just built the amp with Fujitsu 19R-P11 pentodes(wired as triodes) and a custom 48V power supply.
 
There is a local electronics store clearing out their tube stock so I picked out 6 of these particular tubes hoping that they would work from the specs. I will be back for more as soon as pay day hits now that I know these work
 
The 19R-P11 has a heater voltage of 19V too and a heater current of .2amps and seems to work fine without modifying the circuit.
 
This thing really makes my grubdac shine
 
I still need to get a case sorted and need to repaint the heatsink as it got a little scratched drilling out holes for the tubes.
 
Here is everything together for testing:
 
<snip>
 
Pin out equivalent for the 19j6 if anyone else wants to try:
<snip>

 
Well done! Congratulations! It's good to see another version of this design come to life!  Yes, I love mine with my grubdac too
 
cheers!
 

 

[jacobthellamer]

Quote:

 
 
Well done! Congratulations! It's good to see another version of this design come to life!  Yes, I love mine with my grubdac too
 
cheers!
 

 
Cheers!
 
I was surprised how at easy it was to get working.
 
I think I will make use of the pentode screen for my next build

 

[capernicus]

This is incredible work!  Can anyone tell me how to mount heatsinks like these?  Are they screw in from the bottom?  Can anyone recommend a source/part number to get a pair of these?  I'm about to build one for a gift.
 
 
 

 

[tomb]

Quote:

This is incredible work!  Can anyone tell me how to mount heatsinks like these?  Are they screw in from the bottom?  Can anyone recommend a source/part number to get a pair of these?  I'm about to build one for a gift.
 
 
 

I agree it's formidable work.  I can't remember the builder's name off-hand, but he built just about every tube amp available in the DIY section of Head-Fi with just the same techniques.  His magnificent work was based in 3D CAD designs, first, then machined directly from the 3D CAD models, if I remember correctly.  Some of the finest work I've ever seen.
 
As for the specifics of your question, I'm fairly certain that despite the superlative case design, he still used the SSMH PCB, which means those heat sinks were simply soldered onto the PCB by virtue of the heat sink pins.

 
 

 

[livewire]

WOW!
Very nice build, simple and elegant.