Pars

Marc, The goal on these boards in terms of the front end and VAS stage is to Use singles (2SJ74/2SK170 and a BJT pair, currently perhaps 2SA970/2SC2240), and use the heatsinks per the diyaudio thread? A nice to have would be grouping the 2SJ/2SK together (back to back) and the same with the BJT quad? Not sure if that is doable. Referring back to the layout in post 192, the individual TO92s for each dual package device are not oriented opposite to one another, which was what I thought you needed to have for the heatsinks? Let me know if I am making incorrect assumptions on any of this.

Shielded transformer from SumR is cheaper than an Avel plus another case plus good connectors (though JAE and whichever ones were used in the krmathis build are good and not that expensive). Heat may be the trump card however, though I was planning a 2 ch. build, so single chassis = win.

IIRC, KG doesn't like active grounds. I'm not sure I've ever seen a 3 channel dynalo or dynahi. I'll let him weigh in and correct me if he cares to however. The ones I've seen are 2 channel for SE and 4 channel for balanced.

First stab at a BOM. I took the Google one from Headwize and started updating it with some info Marc provided. http://home.comcast.net/~youngc1/DynaFET BOM.xls

Hmm, I wonder. I wasn't sure if he might not even be a regular here or HF... board says Jacob Potter.

Yes, I was looking at that as yours is a very well done example of angle bracket. I just always wondered why most people did it that way instead of mounting the output BJTs straight up onto a rectangular section about the thickness of the board offset (3/8") or so? I guess the angle bracket does lend itself to the board mount for that side and all. It would be nice in the Dynafet project to make the boards so they could kinda interchange in a Dynahi as far as mounting, etc. so you could swap boards in the same amp chassis.

Not quite that far yet, but I'm sure they will. Boards are pretty much done other than putting the transistors in. I also need to decide how i will mount these to the heatsinks (angle bracket or standing up straight onto rectangular section aluminum). SumR transformer on order, plus case. BTW, did anyone happen to download j4cbo's Eagle schematics and/or board files on headwize? Looking at the board, it may be possible to do this in the freeware version of Eagle. Maybe. http://headwize.com/ubb/showpage.php?fnum=3&tid=6584&srch=dynafet;

Fuck you. Still contemplating post 161

definitely... puts my western auto tap set to shame

Oooh, tell me more? I might be in need of some of those... what exactly is a spiral flute tap and where do I go for something like that (+Tap Magic)?

Freeware Eagle will only do a 100x80mm board (~4"x3.2"). I need something that runs on a Mac also, ruling diptrace out (I believe??).

M3 with MOAR POWER?

I don't really care who uses it... the point is they are too small and there is no valid reason for doing them this way, other than the default libraries of whatever layout package being used have them this way I'd volunteer to do the layout but I only have the free copy of Eagle and it won't do a large enough board for this.

Just to contrast, this is the group buy Dynalo board that does allow zip sockets (U1-U4). Pads are still too small in general however.

This is a screenshot of the duals portion of the board. Reorienting them into back to back (quad?) would not be easy...

This appears to be the same case here, as the duals were implemented using individual TO-92s rather than the 7-pin dual socket. Spacing between the pin rows is not high enough to support sockets of any type. Pad sizes and shapes are also on the small side. I prefer elongated pads on transistors, for example. I'm looking at the dynafetr files using external heatsinks.

I'll need to take a look at the board files (I assume Gerbers), and think from what I have read that the Toshiba FETs, external heatsinks (dynahifetrhs.zip) is the one I want to look at? As for the schematic, there is a pair of devices in it... these double to 4 total, the additional pair in parallel with the existing pair I assume (including addl drain resistors (is that the right term))? Dual parts: thru matching, I think you can get better matches than the duals give you... one of my duals has to be 20% off in matching. For the dual BJTs, would something like 2SA970/2SC2240 be a good substitute? A couple of requests on the boards: I always felt the pad sizes on the Dynalo/Dynahi group buy boards were too small, making soldering connections to the ground plane or power planes difficult, and making desoldering from these same areas really hard. Secondly, the footprint used for the dual parts on the Dynahi boards did not allow the use of Zip sockets to socket the devices. The Zip sockets I feel are a must to allow, even though we will be using pairs of single devices here. Like I said, I'll look at the gerbers.

Tried 2 different browsers... nada. As for BOM, is http://gilmore.chem.northwestern.edu/dynagbffet.gif this the only schematic available? This only shows a single output pair. Someone (j4cbo?) on the headwize thread had done a schematic and several board layouts (Eagle), but they aren't available any more.

No. I didn't see the image(s) he referenced previously either.

Oops, copied wrong post for list: luvdunhill - 8 - 4 Asr - 0 - 4 Stretch - 0 - 4 looser101 - 4 -2 PFKMan23 - 0 - 4 Naamanf -? - 4 Icarium - 0 - 4 Dreadhead - 0 - 4 n_maher - 4 - 0 Digipete - [8-12] - 4 grawk - 4 - 4 Pars - [8-12] - 2

As Nate said, oh frack it: luvdunhill - 8 - 4 Asr - 0 - 4 Stretch - 0 - 4 looser101 - 4 -2 PFKMan23 - 0 - 4 Naamanf -? - 4 Icarium - 0 - 4 Dreadhead - 0 - 4 n_maher - 4 - 0 Digipete - [8-12] - 4 Pars - [8-12] - 2 Willing to help build, match parts, etc. Anyone have a BOM for this? I notice one on Headwize done in Google docs, but it seems to need updating (which I can do??).

More like this? no handles

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