luvdunhill

amb uses it for the beta22 boards

Don't you own a Singlepower amp? Anyone know what design this amp is based on, just out of curiosity?

cool! Is it possible then to utilize the 1x4 SIP header and the locations for the current sensing resistors on the prototyping board for anything, or are they more or less unusable? Icarium: Team vvs_75 requested 10 boards via PM, looks like you need to update their numbers.

Doug: In your PSUD2 sim, did you use a stepped load to check for ringing?

Looks like $12.50 per board is the magic number, made to the above specs. Dan charges $10 + shipping per board for the other Dyna- boards, as a comparison price point. This includes parts and shipping for two prototype boards, shipping from myself to Kevin and the initial run of the prototyping boards. This prototyping cost will be split up over the entire number of boards ordered, including Jacob's SMD only version. The divisor at the moment is 88 boards. Price is ultimately determined on the final number of boards ordered, so be noodling on that one.

don't they make clear wood?

Jacob: I talked with pcbfabex and my suspicion was correct with regard to the silk screen issues. Minimum is 6 mil, if it's less than that they try to resize it, which as they said, often results in fail. They said maybe even go up to 7 mil. This applies for the lines as well as the lines that compose the text. I'm not sure what 7 mil corresponds to in "font size" ... who knows. Everyone else: I'm going to talk with Dan soon and we're going to need people to firm up their board quantity. Probably best to do this via PM, so be on the lookout for this. I've talked with four places, all seem very eager for my business. I have two more board runs to bundle with this, so I'm trying to leverage all of them to get us the best cost, and to finalize the quote I'll need to firm up numbers, hence request for participation. Specs I'm looking at are 0.062" FR4, RoHS gold immersion, black solder mask, 2 oz copper. Any suggestions with regard to fab choice or specs would, just let me know. Obviously I'm comparing the "standard" options as well, but from what I'm seeing so far, they are pretty much throwing in these "upgrades" due to the volume and new customer status.

pro standard, or audiophile standard Dusty is on to me unfortunately.

I wonder if microphone cables have a standard on how the shield is (or isn't) connected to the third pin? Is it connected on one end, both ends, or neither end? Not that this standard in the audio world, but it could be another difference.

I'd use 12AT7. Throw one in for the concertina to make 5 total.

yawn... Critical JavaScript vulnerability in Firefox 3.5 at Mozilla Security Blog

yup, I'm a big fan of the regulator with pass device type arrangement for high voltage duty as well, seems to cure lots of little problems, as you've shown above.

meh. I'd rather have this:

Jacob: The silk for the 2SC3381/2SA1349 need to be swapped around. See my board pic here http://www.head-case.org/forums/247143-post899.html

cool beans! I didn't realize the original design was so low

dew eet " Reply by supra_buyer (Jul-13-09 17:35): Please return for full refund if not completely satisifed. No questions asked. "

yup.

Give Mikhail a big "f-you" from us all...

why do I doubt that this is really the case?

Cool. I'll get with you and we can hash it out sometime this week

I have something in the works... pretty crazy though. I use a SLA battery to generate 3 phase AC power. Key components are, precision clock, lots of logic ICs, 41Hz chip amp, and three toroids wired in reverse to step up the voltage. I decided not to use an ipod playing a .wav to generate the control frequency for AC power, that's crazy.

Jacob: The changes look fantastic! I just collected all my notes and here are the remaining suggestions that I have: 1.) On C1 can you enlarge the holes to 1mm diameter? 2.) In post #884 I suggested a change to the silk for the dual devices. It would be great if you could implement this, as this part of the assembly is very confusing. I'm sure someone will screw this up. I'd also add the 2SJ109, 2SK389, 2SA1349, 2SC3381 nomenclatures on the silk as well, per my the mockup part I included in post #884, as you have plenty of room. Trust me, when people are installing the devices, they will thank you profusly for this change. 3.) Along these lines, can we label the positive and negative power inputs? For some reason I blindly assumed the positive was on the left... Glad I double checked it in the end! 4.) Furthermore, can we add the cap ratings as well to the silk? It's hard to tell without really understanding the layout that the top two caps need to be >=63V caps and the bottom for need to be >=35V caps.. Again, I made this mistake, and I'm glad digger945 pointed it out early 5.) For the four bottom caps, I think if you separate them out a bit, you might be able to cram in slightly larger diameter caps. I guess what I'm asking, is it possible to make the bottom four caps 18mm diameter as well? 6.) I'm not sure what your DRC rules are set to, but the output pad seems very close to the FET pads. In looking at the copper, if you moved the output down a bit, you could perhaps get another fenestration to connect from the power planes to the output FETs, and that might be worth it. I'm not sure, but it might be worth looking at. 7.) Would it be possible to go back to the prototype buffer layout where none of the transistors are facing each other? I'm just concerned because these get so hot that the BJTs will start to runaway and the buffer become unstable. I liked the prototype layout where there was two rows and they were all lined up. I think you could even space the two rows apart a little more to help with cooling, and if this is possible, which it looks, I'd definitely try and do this. If you want to face some of the transistors together, I'd recommend the CCS transistors (i.e. the three pair that are not a part of the buffer) as this could potentially help the offset be even more stable. For example, I'm not sure if the BJT facing the LED is the best idea, but who knows. Maybe at minimum you could turn these two to face each other? 8.) Pars recommended a flush socket part in post #886 that may be worth looking into supporting. Looking into it, it's an easy change I believe... along these lines, I'm assuming it was too hard to enlarge the outer pads on the resistor footprint? You mentioned that you might be able to do this in post #893. I'm assuming this wasn't possible? Even the smallest amount of room would be greatly appreciated, as it's a very tight fit and many of us are hoping to use PRP resistors, which due to uneven tolerances will be even tougher to fit than the Dales. 9.) I noticed that all the holes on the top of the board for mounting the FETs and the board itself almost fit a #6 screw... maybe it's a M5 hole? Anyways, could we enlarge these a tiny bit so #6 would fit without "threading" the through-hole plating? 10.) You might want to make the screw on the center pot point to the right of the board, as that way the value will be visible when it is installed and hooked up to the heat sink, since this is a rather important value for determining the bias range. I had the hardest time trying to read this value once it was installed on my heat sink Obviously people can swap the part themselves, but the silk is a good reminder 11.) I'd line up R57-R58 with R7,R8,R10,R12 and line up R1-R4 with R59, if possible. I like resistors in nice neat rows I suppose Finally, what PCB fab are you considering? I'd sort like black solder mask, with gold plated pads, with 2 oz copper Depending on where you get the boards made up, these aren't really all that expensive. Check Phoenix Gold for example, who even offers colored solder mask and gold plated finish for free for larger orders, and at a nominal cost for smaller orders. I wasn't so impressed with the silk screen from PCBFabEx, but everything else was top notch... However, I'm not sure that their quantity pricing is very competitive, compared to some of the other places, hence the question... oh, and black boards FTW.

digger945: cool! Can I also get the Vf for the LEDs in the buffers, so I can finish calculating the dissipation there? j4cbo: I'll sit down and print a copy of the boards out and look over them tomorrow, but on first glance things look perfect!

Kevin discussed this in posts #1001 and #1076. I did as well in a few more posts.

bah, wasting all my matching efforts and raising output impedance? madness!