luvdunhill

Let's see.. 20K in the middle and 10K on the sides. I think that's right :/ I use two types of solder. Johnson IA-423 ternary eutectic (4.7% silver, 217C melting temperature) solder with various fluxes and WBT 8020 (4% silver, 180C melting point). The Johnson is much "slower" solder, making it ideal for certain types of uses, where the WBT is "faster".. I think you're probably seeing some of both on this board, heh. The Johnson is harder for me to get a hold of, but now it seems that PcX sells it with a different flux than I'm using now. You can buy direct from them in 1 lb spools and get just about any diameter / flux combination. I think it runs around $25 / lb from them direct, but I bought 3 lbs from them 2 years ago, so it might have gone up, who knows. Nice stuff. You can make it flow faster by adding extra flux, and I do this quite often, as you can see from the top of the boards there... I really want to look into getting a more aggressive flux cleaner, as on larger boards alcohol + air can doesn't work so well, but haven't gotten around to looking at the Johnson site to see what they recommend.

try woo*********** edit: fail

ok Jacob, everything fits. No need to move the JFETs, they are perfect. Still need to double check the orientation of the TO-92 parts, but it will have to wait until tonite, unless someone else can look. The jumpering for the regs is a bit annoying (pin 1 to 3 on one and pin 1 and 2 on the other), and given how slick the feedback jumper is, could a similar SMD jumper be added to the bottom of the board for the regulators?

Gotta head out, and will be busy until tomorrow night Maybe I can get another set of eyes to double check the transistors? I'm most worried about the orientation of the 2SC3381/2SA1349 and JFET "singles". I double checked it, but you never know. From top to bottom, left to right I have: JJJJ KKKK (not populated yet) ACC CAC ACA AAC AC CC AA AC AA JJ KK CC ... and pics to show orientation of the "duals"... zoom all the way when you view the pic, as the light made things hard to capture, and seems to make it look like there are some flaws in the dual assembly, which are pretty much smooth when looked at straight on... oh well, just a bit self conscious I guess Tomorrow I need to jumper the regs, jumper the feedback and install the MOSFETs. Then have to bolt my sigma22 to the heat sink and get things ready to flip the switch. I'll probably load test the sigma22 first, assuming I can find enough power resistors around here.

nope, never heard anything on Andromeda, that seems to be the other sale label? Last thing bought includes the following from Amazon: # 1 of: Windows Debugging: Practical Foundations Sold by: Amazon.com, LLC # 1 of: The Unofficial Guide to California with Kids (Unofficial Guides) Sold by: Amazon.com, LLC ... and a Squeezebox Classic from a member here!

cool, I like Pentatone. Any good deals?

yup, air

meh, but can it hit 1 Hz at 3 miles away like the one I posted? http://www.rotarywoofer.com/KING_IS59_Summary.pdf ... that U-Haul has some serious bump.

heh, nice one Those are the only parts I'd want to salvage out of Mikhail's amps. I have some of the older Vanderveen (sp?) design stuff, and they are quite excellent.

Not for these frequencies. 1W 1m is the standard for SPL. There simply isn't a standard for measuring Xmax, see my article above. SPL also accounts for Sd, so you can compare different diameter drivers directly. I've measured this many, many times. Hell, microphone calibration doesn't even come into play at this sort of measurement. I'll give it a rest.

because, it's a rather bogus parameter. The resulting SPL would be more appropriate comparison in my opinion.

meh, go with this: Eminent Technology: home

Xmax is a crock. I mean, what distortion to you define? I could define Xmax = Xphysical, why not.. I'd have a ton of distortion, but hey. If you think everyone uses a 10% number, you'd be wrong... It's just like Watts... without clarification, it's rather meaningless. edit: just found this link, good read: http://www.aespeakers.eu/knowledge-base/the-deal-with-xmax.html

nope. What about difference between underhung and overhung voice coils? Different topology means you cannot compare the numbers directly.

geez, are we going the have the "my Xmax is bigger than yours" worm-hole discussion? edit: heh, posted at the same time as Tkam

Please dispose of those two, large round canisters properly by sending them to me. Thanks!

one thing to do at a minimum is work a way to add a test point in somewhere, so we can easily measure across the output resistors to set the bias. This has PPAv2 type slip ups written all over it. I started installing the transistors, but thought better of it after 6 or so. I want to verify the schematic to make sure I get the polarities right.

one other option.. you could easily make the two paralleled transistors before the buffer face each other (flat side would mate on the silk), as well as the two transistors in the CCS so that their faces could be bound together with a zip tie and some thermal grease. (so, all the non buffer transistors could be bound together in pairs, three pairs total) I've done this and it works very well. You can move a single trace to the top and do this quite easily. I think I'd slightly prefer this. What do you think? Then you'd need a way to mark the polarity, maybe a dot or shaded version of the outline? What other TO-92 silk patterns does EAGLE have? Look at the photo. See how the second row output resistors are almost right up against the Dale resistors? The PRP are a bit fatter in the worse case (their body seems to have a looser tolerance) I think as well. Just a bit more room here would be nice, if you cannot also separate the two output resistor rows. It's really tight in there... what about a hair more pitch, say 0.5mm? This is probably more important, as the PRP resistors are kinda fragile if you slam the leads against the body like we need to here. The larger pads seem very doable, as I'm looking at the silk now and would be greatly appreciated. perfect! I think we can safely remove C32B. The other input capacitor is basically equivalent, and this way is better given the feedback capacitor. The mica option for the feedback cap doesn't quite fit. I dunno why CDE has odd pitches, but I'd look at the datasheet for the one in the BOM and make the distance from the second hole from the bottom to the top hole this exact pitch, as I had to really shove it in to get a good fit... If you look at my pics, I'd move in the 2SA1139/2SC3381 pairs towards the middle of the board about 1mm or so (I'll measure to be exact, but look at the one on the right in the pic, you'll see how much room you have). The fins of the heat sinks are very close to the resistor leads. We will almost assuredly have to move the two JFET pairs closer. I didn't have time to build and document how to put these together tonite, so perhaps tomorrow I'll get to it. edit: so you see why the silk is confusing for the regulators by looking at the pics.. alternatively / in addition, we could put surface mount parts on the bottom of the board, but I think just using the TO-92 parts and scrapping the TO-220 silk is fine... Anyways, things are looking like I'll power it up on Friday late or Saturday evening.

Sorry, the Audio-gd Phoenix design looks like shit.

A few pics that illustrate some of my points above:

Tickets from Austin to San Francisco and Vegas to Austin for the whole family! Now to attend to other planning details I suppose.

eh, you lost me after the drill part

I'll check tonite, but these should fit fine for the 7zip packages. Would that suffice? Mouser 575-410322010

well, I have the boards and have started working with one and getting the other ready to send to Kevin. Not an easy board to stuff so far... A few initial suggestions, in random order: 1.) The silk is sort of messed up in places. Kinda like printing on a bad ribbon, for those that remember those days, it's offset at points. I'm assuming this is an issue with the fab, not the files? 2.) The output transistors I think could be better labeled using "2SJ" and "2SK" rather than Q27-Q34. I'd remove that A17,5mm text as well (whatever that means). 3.) The top ground plan extends too far and will be under my aluminum angle, which I'm uncomfortable about. I'm not sure if this will be the case for everyone, but I'd like to move back the ground plane to the most northern edge of the pads. This will cause some of the ground plane in the middle of the output devices to be unconnected and thus removed, but this is okay. 4.) The "1145 / 2705" legend will be partially hidden by the bracket. I'd move it down a bit. Also, perhaps another legend would be more appropriate, as there are four transistors in the middle that are at a 90 degree angle and have no reference designators that I need to track down on the board files to see what polarity they are... maybe add a dot to all the 2SA devices right above the center pin? That way you could accommodate the mystery devices in the middle of the board that are currently at a 90 degree angle from your legend. 5.) If at all possible, there needs to be more room around the output resistors. Especially between R53,R54,R49,R50 and the row below it (R44,R46,..). The bodies on these three rows of resistors practically touch. Any more room would be greatly appreciated. Looking at the layout, you can create some more room at the bottom quite easily. Move the JFETs toward the power connector and move the regulators around a bit and move up R57,R58, etc. You get the idea. More room between the first row and second row of the output resistors, as well as more room between the second row of the output resistors and the R44,R46... row. I think we definitely need to do this. 6.) R33 and R32 actually touch the caps. These should be moved out a bit, you have plenty of room. 7.) On most the caps, I'd remove the "A" and "B" nomenclatures. It gets confusing. Less text is better. Also, I'd remove the smaller silk screen and just keep the larger outline on C11B, C12B, C13A, (and the unnamed capacitor to the right of the power connector), C32B, etc. It's clear enough with the single large outline with the four pads inside and helps the silk look less busy. 8.) The resistor between R28 and R32 has no printed reference designator, that I could find. 9.) On C1B, the south hole could be enlarged a tiny bit, as I cannot quite fit my capacitor in there. I can give the component dimensions, but my guess is as large as the IN connector holes would be great. While everything fits, it is tight in there. I'd move C11B to the left a bit and then C1B to the left as well, since currently everything touches. *10.) In my opinion, the resistor foot print is just too small. I know it will be hard to enlarge it, but I think a lot of people aren't going to like the fact that you have to slam the leads against the body and then the ring gauge on the board is so darn small. I realize it's work to fix this, but I think it will be worth it, as it's very, very tight. I'm just preempting Pars complain on this matter I dunno what to say... it's very, very tight. 11.) I'd add a silk layer to the bottom to explain the rather clever jumpering system and a note to the top of the board explaining that the bottom jumper must be populated. I didn't even notice it myself until I looked at the EAGLE files. 12.) For the four 7zip patterns, I think this will be confusing to stuff, since we're using the small device heat sinks. I know mistakes will be made and people will have to consult the data sheets as is. See attached image for what I'd recommend to do here for the silk. 13.) Depending on the connector you want to use for the 4 pin SIP to the left of the power connector, I'd recommend putting a bit more space between here and the cap. For example, you might want to use a Molex KK connector that has the retention clip, and currently it wouldn't fit. 14.) For the two regulators, I'd use the TO-92 silk pattern. Since the higher voltage parts aren't available in TO-220, I think we should just use this pattern and emphasize this on the silk. The polarity needs to be marked somehow as well. Ok, more tonite after I finish stuffing the boards. Simply a gorgeous design, by the way... hats off!

I think I heard that phrase last time I was in London, and it wasn't a good thing...