Millett "Starving Student" hybrid amp - Page 24

My parts arrived. I've been starting to sketch out a wiring diagram. I've downloaded some data sheets.

Why on earth doesn't the IRF510 data sheet include a key to the pin numbers? I assume that when looking at a T0-220 chip from the printed side, they are 1,2,3. Sigh. I am clearly a bit further over my head than I'd hoped.

Nah, you're not over your head. Good rule of thumb for this stuff is "if you don't succeed, try, try again." I always check the data sheets from multiple suppliers if I don't find what I want clearly in the first sheet. Try this one from Fairchild. I compared that one and Intersil's and they both have the same layout (which I'm sure is standard for all of them).

Thank you! And there I was thinking I'd been persistent : )

Hello Pete and everyone else here. I am interested in building this amp for myself. The tricky thing is that I am in Australia so sourcing parts from multiple places would be difficult. Is there any way to order most of the parts from one source? Are PCBs still available or do you recommend PTP?

I have limited electronics experience. I have rewired some guitars and toyed with pedals etc but I have always wanted to make a tube amp. I wanted to start with the simplest possible project for the least amount of money so it sounds like your design is ideal.

If anyone on Head-fi has built one of these in Australia, your input would be much appreciated on how to go about sourcing the parts needed. (and building with 240v power supply)

I haven't checked today, but Mouser was out of C2 and C4, the .1 uF/63V film caps. I found some elsewhere, but they are .15uF instead.

How much is that going to change the amp? It looks like it would change the relationship between pin 1 of the tube and Q1, but what that is I do not know...

@royewest: when I built a CK2III, I did the same thing. I checked way too many spec sheets and even consulted many photos of completed builds so I would KNOW that I had those babies in right. No worries. Once you get it laid out, you will succeed!

I'm in the process of building a few of these to sell not-for-profit. Maybe I could send a kit of parts. I'm not sure right now. Anyways the version I'm building is using higher end stuff than the bom.

I'm pretty sure the recommended power supply works with 240v - you just need a different cord (~$3)

Pete recommends 0.1 - 0.22 uF caps for that spot. These are a good choice: MKP2-.22/100/5

OK, I am having some difficulties getting this little bugger to work. I have looked over my joints and all look good. Basically nothing is happening when I throw the switch, the power supply starts ticking at me (~twice a second).

I noticed that in Nate and Pete's builds the fet bodies/heat sinks do not seem to be insulated from ground which neither are mine, but upon looking at a data sheet, I read you must do so. Could this be my problem? I will post some pics late if there are no ideas based on my description.

Thanks. I didn't see that!

Very likely. The BOM does have a listing for Transistor mounting hardware which includes an insulator. It is listed to be at mouser under part 532-4880.

Yeah, checking the datasheet the tab of the mosfet is connected to the drain, which is pin 2. That is where you are feeding +48v into, so you have a dead short from +48v to Gnd.

We have Music!

This little sucker is sweet. I can't believe how quiet it is. I'm talking no hum even at max volume (no input of course). I used 470 Nichicons at c1,3,5,6; Wima .1's @ c2,4 and 1% metal film resistors from Radio Daze. I ordered my pot from Radio daze as well to get over the minimum order amount.

I am very pleased with the sound thus far. I feel like it extends very nicely on both ends of the spectrum, and It lacks for nothing in dynamics. The only "tell" that this is a budget amp is a very small loss of inner detail. Thanks a ton to Pete, your ongoing contributions to the DIY community are priceless. You've got my first ballot vote for DIY Hall of Fame.

Eye Candy: (I still need to trim the pot shaft to accommodate a nob)

How'd it compare to your CKKIII and Zhaolu Discrete?

WOW!!!! That case is awesome!!!

My MOSFETs are certainly isolated, or else I'd be having big problems. I used an insulating washer similar to the one called for in the BOM.

Thank you. It was a small three piece plier kit. Needle Nose, Diagonals and Flush cutters. I must say I am quite pround of the way it turned out.

Yeah I figured that out. Luckily this particular screwup was relatively harmless.

Let me listen to it for a week or two and I will post a comparison.