luvdunhill

yeah, stock idle heat dissipation is around 62 watts stereo. I have one channel running now on my bench and that's almost exactly what I got. I'm at around 22 C temperate rise above ambient. Once you get it, I can help you measure it and you can figure out exactly how it's biased and what it's output is and when it leaves class A. I'd personally turn it on for 12 hours or so and measure the DC offset voltage before I hooked it up, but that's just me being paranoid. Nelson recommends a few weeks burn in before being sure the DC offset is in spec, and somehow I doubt the builder did this... Another thing about buying on the "DIY-market" is that you really need a distortion analyzer to tune this amplifer, according to Nelson... that's the only way you'll get the specs posted, as he's been quite candid about that.

yup, 0.6 C/W per transistor hence the pair. Trust me, this builder had to of lowered the rails or this could be another example of epic fail. Also, everyone over specs what Papa recommends, as those strangely configured, non-conventional heat sinks he uses seem to have magical properties.

F5 puts out 50 stereo watts... my guess is those heatsinks can do 20-30W total.. welcome to class A. From the article: "Heat Sinking At 1.3 amps per channel, you will see idle heat dissipation of 62 watts. To keep the temperature rise of the heat sink to 20 deg C. above the ambient temperature, you will want a heat sink rated at about .6 deg C./watt for each transistor. An example of this would be a chunk of finned aluminum, with a series of 2” fins attached to an 8” by 6” base. You will need two per channel. The output devices need to be intimately attached to the heat sink. The mounting surface on the heat sink should be at least

I wanna go so bad... perhaps I can get you guys to snag some freebies for me

He must of really lowered the power output on that to get away with those heat sinks... or it's going to cook. Ask swt61 about the heat sinks I'm using.

point being: A.) buying black market DIY stuff is lame.. I wonder why he removed the Audiogon listing so quick... B.) the reason he charges less than the MSRP is because there is not much to it when you don't have to design the circuit just copy someone else's ideas.

NP will be offering the boards only for the basic schematic, not the more advanced balanced versions that people are building. The kit I'm referring to can be bought at tech-diy from Jack: Tech DIY Company Store

yes, there are 2 people doing dual transformers.. me with the ghetto ones from surplus sales that are posted in this thread (still haven't figured out which set of wires is the primary and which is the secondary) and swt61, assuming he can shoe-horn 2 donuts in the case somewhere trick mods? hm.. you could look at lowering the JFET degeneration resistors and playing with bias points... perhaps add a choke in the power supply somewhere... uh, I dunno...

yeah... you get my point though. It's a very simple amp, as all the first watt designs are. Add in $80 or so for a Plitron toroid, $50 for binding posts, $10 for IEC inlet, $12 for XLR jacks, and $200 for a chassis and you're still well under $500.

yup, the battery is used as a reference.

so, I've been playing around with some diodes on a power supply and found some I like, but I think I'm cutting it too close with the current rating. The transformer is 82VCT 50VA R-core and I have a 300mA fuse on each rail after the main supply capacitance, which is around 3000uF per rail. I wouldn't expect any more than 300mA per rail, hence the fuse choice. That being said, there is in-rush and the like to consider, and blowing a bridge isn't too exciting in my book. So, without admitting how stupid I was, and how low I went... in your opinion, what's a good rule of thumb?

hm, I don't know. I had most of the parts on hand. Probably $20 or so, plus the power strip? Here's the chassis I recently saw that would work really well: Odio Power Stripe Box Main

easy, look at the part cost You can get a kit for $26 per channel.

sure, I'll try and document things... I'm done counting out most of the parts. The caps larger items are proving quite bulky to pack. I'm going to go to the post office and get some flat rate boxes tomorrow, as these kits definitely have some heft to them.

problem is I was working on moving my JFET matching jig from breadboard to perfboard, and making it where I could match 4 devices at a time... so, kinda bad for you guys too

yup, I've played with this "design". I found a really nice donor chassis at some point to use and recently saw an even better chassis somewhere (I think at thlaudio). Seemed like a good improvement, but not on the level of say a isolation transformer or good filtering in the component itself.

they indeed are... today the parts arrived.... a lot of parts... then I figured, screw you guys I'm going to go work on my own projects and pack this stuff later... then my heating element went out in my soldering iron

Just picked up two transformers, for $35 shipped: -Thordarson T22R31 76VA, 360-0-360V 80ma,5V 2A,6.3V 2.5A. -Stancor P-6170 600-0-600V 200ma,5V 3A,6.3V 3A,6.3V 4A. hmmm...

good catch. I'd say *most* of the time you cannot do the double-and-half...

probably some amb goodness... As for "relative bargain", you should compare DIY to DIY as well. I'd be curious to see that cost differential between the β24 and say a Pass F5, or one of the Krell KSA clone projects. My guess is the β24 is 3-4 times more expensive than those 2...

nate, what did you end up using here? I need some sort of silicon adhesive for securing some capacitors and what not. It needs to be insulating as well, as the caps have metal casings. I remember a thread somewhere about silicon adhesive... I looked at Home Despot yesterday and really couldn't find much to fit the bill ...

UPS is estimating Monday for delivery of the parts, so I may be a bit later in sending them out. I'm not sure what I did to anger the gods, as Digikey has always basically been "next day" to my house, no matter the shipping method...

like this?