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[SripBoard Design] Starving Student Millett Hybrid Vacum Tube Amp - Page 7

post #91 of 269

im pretty sure caps 7 and 8 are to help with noise floor, but if you use the right cap (nichicon muse es for example) it improves the sound, especially bass handling. id put them in there its maybe 2$ more in parts.

 

as for the resistors, 1/2 watt will work absolutely fine. they are considered overkill, but there only detriment besides cost is that they are physically larger. 1/4 watt is still on the safe side, there cheaper (not by alot, but still) and their smaller. size isnt a big concern as you are not using a production board, but if you were, you would need the 1/4 watt resistors becasue 1/2 wouldnt fit on the board.

post #92 of 269
C7 and C8 are decoupling (or bypass) capacitors. They decouple the signal being developed across R5 and R11. They are pretty important and a basic element to the design of the amplifier.
post #93 of 269
Thread Starter 

Okay here is 3.6, Hope i solved everything you mentioned! Worked a bit on the layout so it would be cleaner. Hope the arrows are not in the way.

V3.6.jpg

 

@digger945 i promise to work on buying parts as soon as the website is working!

post #94 of 269

looks good! i think its ready! just remember you need to take r3 and r9 off the board and attach them to the leg of the mosfet. you want them as close as possible.

post #95 of 269
Could you give a link to the power supply you will be using?
post #96 of 269
Thread Starter 

Thats great news!

 

Sure here is the link for the PSU: LINK


Edited by TestSubject - 8/9/11 at 2:07pm
post #97 of 269
Thread Starter 

Website back Online! Did this very quickly, and i cant find the proper resistances... Will it be okay? (Cant buy 1/4 Watts resistors other then in packs of 100)

 

Will add all the other components tomorrow. Ho and if you could have a look at the Caps.

 

BOM.jpg

 

PS: can go lower or higher but no 2K or 50K

 

Thanks

post #98 of 269

i dont think it will be a problem. this amp is not super sensitive to resistance. you could also use 2 1kohm resistors in series,

 

               Rtot=R1+R2+R3...

post #99 of 269

On your previous order you had 1/4 watt 2k ohm resistors shown. Now everything is 1/2 watt. Either one would be fine, or like kchapdaily mentioned you could use 2 or the 1k in series, or 2 of the 4k parallel.

 

From where are you ordering parts in France?

 

post #100 of 269
Thread Starter 

Ho yes i forgot i had found a 1/4 Watt 2K ohms resistor. 47K instead of 50K would be fine? I mean i could 47+3 but is it worth it?

 

I am ordering from http://www.conrad.fr

 

EDIT: if you happen to know a better one please let me know!

 

Thanks

post #101 of 269
Thread Starter 

Got an enclosure (Rather large Wooden Cigar Box) and a computer heat sink with possible fan.

 

Box.jpg

post #102 of 269
Thread Starter 

VERY quick sketch for a 1 tube version:

 

Screen shot 2011-08-11 at 12.17.40 PM.png

post #103 of 269

You can share one tube for both channels in this amp? I didn't know that.

 

Cool cigar box by the way, looks like you would be able to include a built in dac in there too!

post #104 of 269

im not sure if those heat sinks will be suitable. is there a hole or bracket for mounting a to-220 part? if not i recommend buying a heatsink designed for to-220 parts. 

post #105 of 269
Quote:
Originally Posted by jdkJake View Post

C7 and C8 are decoupling (or bypass) capacitors. They decouple the signal being developed across R5 and R11. They are pretty important and a basic element to the design of the amplifier.


They are not a basic element to the design of the amp, Pete didn't have them implemented in his original design. They were added in when dsavitsk (I believe) added in his improvements, and can be left out. I know for a fact that Beftus had at least one SSMH where he disconnected C7/C8, he noted that it reduced the overall gain but otherwise didn't change too much.

 

As for pin 9 on 12AU7, it is used for a center tap (instead of 12.6V, 6.3V) and can be utilized in some single-tube designs (like the Bravo amps on eBay). We don't need it here so it's not connected to anything.

http://en.wikipedia.org/wiki/12AU7
 

 

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