luvdunhill

you can practically count the number of components on 2 hands for this one. Maybe I can get some secret camera footage of swt61 doing a F5 for your viewing pleasure.

F5

I'd appreciate it not being open to the outside world. I got all kinds of spam from the Pearl deal and I'm trying to keep this small enough to be advantageous from a cost standpoint but not unwieldy. Plus, I'm counting on the group to help weed out :asshat:s, as this could be a serious drag.

oh, I forgot about -=her=- ... thanks for the reminder.

yeah, good luck with that

1x Copper Flat Bar .500" x 3" x 12" - Class II 1x 3003 Perforated Aluminum Sheet .063" x 24" x 24" 2x 6061-T6 Aluminum Square Bar .375" x .375" x 48" UPS shipping Total: $60 seems to be an extremely good deal, we'll see what it looks like when it gets here.

With the GBP in the crapper, I think now would be a good time to try some Sowther transformers for conversion

SMD resistors can get very exotic. Susumu has some 5ppm, 0.1% parts as does Alpha: http://www.susumu.co.jp/english/pdf/products-j01-04.pdf [url=http://www.alpha-elec.co.jp/e_machine.html]Alpha Electronics Corp.

I like Susumu and the KOA RK73A. I believe both DACT and Goldpoint use KOA resistors.

would tombstoning these resistors be acceptable?

heh. There are a lot of other (reasonable) 0.200" options out there, like the Phoenix 0.6W MRS (I think?) series and the blue Vishay series. You can also tombstone larger resistors. If this isn't all that interesting to people, now's the time to speak up. Jacob: Can we remove the ground plane from around the output pad and up, so there isn't any chance of the L-bracket scratching through the solder resist layer? For the large output resistors, I like the Panasonic ERX series, which are available in 1W-3W. http://www.panasonic.com/industrial/components/pdf/AOA0000CE18.pdf What are you thinking for the caps? Something like Nichicon UHE 50V, perhaps? http://products.nichicon.co.jp/en/pdf/XJA043/e-he.pdf I'd also add some film bypasses, something like Wima FKP2. There is a 10nF/63 DCWV that is PCM 5mm 5.5mmx7.2mm that might work well

I think it would. At least that was the case when I played with it on a design I've been working on. I found a good write up somewhere in the documentation for the Leech amp I'll find and post. I pretty much followed the concepts like a recipe and it worked perfectly. Also accounts for phase issues, though in a slightly less elegant way.

a LPF would also require recalculating the global compensation cap, right?

Basically, the input JFETs need to be just like the Vas duals, except the 4-pin side needa to be placed back to back (i.e. one rotated 90 degrees) and the pins 5mm away from each other. Like this: -0-0-0- 0-0-0-0 -------- 0-0-0-0 -0-0-0- where the distance between the second row of text and the fourth row is 5mm.

the input JFETs are not correct. They should be layed out just like the 7-zip packages.

Pete: We all appreciate your enthusiasm, but you do realize that the lead time for the parts (then resulting matching) will be the long pole in tent here? We will have plenty of time for the boards, trust me

For balanced I'd recommend 160VA 2x30 VAC. I'm planning on using Plitron 057017201. I don't understand all the consternation about a single box build. Look at the number of power amplifiers out there that don't use shielding and using much larger transformers... not all that many two box power amplifiers out there. Anyways, if we need to agree to disagree on this one, I'm fine with that. The group just needs to come up with a recommendation, preferably a single model. I think the SumR toroids are a "good value". I have a custom unit sitting right here in front of me and have another large 2x18VAC unit as well. I'm still waiting to hear back on some more of the semiconductors. Interestingly enough, I have a friend within Renesas that I had no idea he worked there. Small world. Lead time is pretty long (~8 weeks), and that's what I'm trying to work around now. Chris, thanks for your help with the board quotes. I say we just call it $15 per board and use the extra money as a deposit on shipping and packing supplies as well as funding for the prototype boards. I'd rather estimate high. That leaves the rest of the work for me in firming up estimates on semiconductors and heat sinks so we can take deposits for those. I'm waiting to hear back from 2 more bids before balancing cost versus lead time At this time, we can target firm quotes for the end of this next week.

yeah, that and things like Caddock MK-132, Vishay VSH/VSC and S102, and Texas Components TX2352/TX2575 ...

yup, also check out the heat sinks towards the start of the thread for the desired orientation for the input JFETs and VAS BJTs. Also, I vote for adding 0.2" pitch footprint for the resistors... in fact, what about a combo 0.2" and SMD footprint? I think that would be sweet.

doesn't look like it to me ... He just used that footprint on the silk. Notice the connections between the 2SC3381 and 2SK389.

If the layouts will work for the dual parts, they will work for the heat sinks as they were made to retrofit a pair of single devices into the dual package. I suppose I'm confused here? I'll look at it again tonite, as I gotta run.

yup, looks right. I'm confused why these heat sinks won't work? The 2SC3381 is "BCE ECB" so just flip one of the devices and things should work, just like with the JFETs. I hope I didn't miss anything.

I can only guess what you're doing, hence the recommendation of the second item which seems to have no relation to what you asked for

something like this? eBay Motors: Universal cd-rom drive controller with remote for diyer (item 290293563954 end time Mar-04-09 06:10:19 PST) and perhaps this: http://cgi.ebay.com/Hard-disk-IDE-MP3-Controller-Board-with-LCD-Display-DIY_W0QQitemZ190283472765QQcmdZViewItemQQptZAU_MP3_Players?_trksid=p3286.m20.l1116