Millett "Starving Student" hybrid amp
Jun 5, 2008 at 2:29 AM Post #392 of 7,277
Quote:

Originally Posted by m0b1liz3 /img/forum/go_quote.gif
Has anyone compared the SQ of the MAX to the Student version???


In a couple weeks when I get around to building my Student, I'll compare it to my Mosfet MAX.
 
Jun 5, 2008 at 3:56 AM Post #393 of 7,277
with thermafilm pads does the grease go between the transistor and the pad or between the pad and the heatsink? or both?

also, is it ok to route the wires for my pot ground and output ground thru pin 4 of the tubes? (pot thru one channel's pin 4, output thru the other's) The reason I want to do this is because the tube sockets are right in the path of the output and the pot to ground, and I'm running out of space on my star ground's solder tabs
 
Jun 5, 2008 at 4:03 AM Post #394 of 7,277
Quote:

with thermafilm pads does the grease go between the transistor and the pad or between the pad and the heatsink? or both?


both

Quote:

also, is it ok to route the wires for my pot ground and output ground thru pin 4 of the tubes? (pot thru one channel's pin 4, output thru the other's) The reason I want to do this is because the tube sockets are right in the path of the output and the pot to ground, and I'm running out of space on my star ground's solder tabs


Yeah, why not? Any point in the ground is fine.
 
Jun 5, 2008 at 5:34 AM Post #395 of 7,277
Quote:

Start to finish I'd wager that these amps take a good 8 to 10 hours to build, each amp that is.


I made mine in about 3, including drilling the case and waiting for the heatsink glue to set. Starving graduate students are also busy!
biggrin.gif
 
Jun 5, 2008 at 5:50 AM Post #396 of 7,277
Quote:

Originally Posted by pinkfloyd4ever /img/forum/go_quote.gif
with thermafilm pads does the grease go between the transistor and the pad or between the pad and the heatsink? or both?


If it's truly "thermafilm" (Avid trademark), those require grease. If it's a "thermasil" (another Avid trademark) or "sil-pad", don't use grease, period. It will actually interfere with the sil-pad's heat transfer effectiveness. You might as well not use them if you use grease.
 
Jun 5, 2008 at 5:56 AM Post #397 of 7,277
it is thermafilm. It actually looks & feels like camera film (if any of you kids know what that is). I got the Aavid mounting kits from mouser. I would've preferred thermasil but I didn't feel like waiting for the Thermasil kits to come back in stock

Quote:

Originally Posted by trains are bad /img/forum/go_quote.gif
I made mine in about 3, including drilling the case and waiting for the heatsink glue to set. Starving graduate students are also busy!
biggrin.gif



WOW that's really fast. It's taking me FOREVER. It's my first real ptp project and it really makes you appreciate the work that goes into having PCBs made
 
Jun 5, 2008 at 7:57 PM Post #398 of 7,277
Quote:

Originally Posted by pinkfloyd4ever /img/forum/go_quote.gif
it is thermafilm. It actually looks & feels like camera film (if any of you kids know what that is).


Sad, but true. Hey, I shot a roll of Ilford Delta in my Holga a few months back....! Real film!!!
 
Jun 11, 2008 at 1:18 AM Post #400 of 7,277
Thanks for the nice impressions, holland!

For some time now, I've been considering conducting a little experiment: build a proper "Starving Student" with the great Mr. Millett's BOM and also a "Stupid/Silly/Sorry Student" version with boutique parts (dumb student is starving and can't buy books now due to overspending). I would love to have the two side by side to compare, so I think this will be a fun project.

Anyone have any suggestions on what I should sub in for the boutique version? I was thinking PRP resistors (maybe some bulk metal foil vishays for the cathode resistors), Blackgate WK caps, Spraque VitQ's. Any suggestions on different boutique parts or possible replacements for the IRF510?
 
Jun 11, 2008 at 2:26 AM Post #401 of 7,277
This looks so sweet. I just ordered some tubes from RadioDaze (amazingly fast service).

It's actually proving harder to locate a 48v power supply. eBay is full of promising offerings but it's surprising how many people only ship to the U.S.A.

Did anyone buy a bulk lot of 48v supplies and if so, would you be interested in selling one to an Australian?

Thanks,
Jarpy.
 
Jun 11, 2008 at 5:05 AM Post #405 of 7,277
Quote:

The ripple is about 210mV, but after the 1000uF C1 cap, it's about 30mV. I didn't measure after the C6 filter.


How did you measure this? Just use the AC setting on a voltmeter, or do you have a scope?
 

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