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tangent  Headphone Council Joined: Aug. 27, 2001 |  Message [#140] posted on: 03-18-2009 05:29 AM CST (US).   |  |  The board footprints are for 5mm LEDs (as it was on PIMETA v1), so your 3mm LED won't sit down on the board. Not that I'd want it to. When I board-mount the LED in a PIMETA, it's because I'm using it to illuminate the interior of a clear case, so I want it about half an inch above the board, to better cast its light around the board. When panel-mounting it, you can just use hookup wires to the pads. |
| kristleifur HeadWizer Joined: Apr. 10, 2006 | Message [#141] posted on: 03-18-2009 10:14 AM CST (US). | |
For what it's worth: I'll be using as many SMT parts as I can. Local availability is limited so I doubt it'll be 100% SMT. |
Mister X HeadWize Fanatic Joined: Jul. 23, 2003 | Message [#142] posted on: 03-19-2009 01:23 AM CST (US). | | How wide is the board? (Are 7343-20 tant caps going to fit between the Serpac enclosure and the bottom of the board?) |
| joneeboi Member Joined: May 4, 2007 | Message [#143] posted on: 03-19-2009 08:38 AM CST (US). | | I can go all SMT. It would be nice practice. |
| tangent Headphone Council Joined: Aug. 27, 2001 | Message [#144] posted on: 03-19-2009 12:53 PM CST (US). | | The dimensions are 3.1" x 2.4". If not, you can certainly go thru-hole here. As to the offers to build all-SMT, thanks. I don't want to push everyone to build it that way. I just need to be sure that all SMT pads get tested at least once, by someone. I'll be going all thru-hole except for the buffers, for this first build. |
| joneeboi Member Joined: May 4, 2007 | Message [#145] posted on: 03-19-2009 05:28 PM CST (US). | | One of the cool things about the SMT/through-hole duality is it gives the builder convenient test points for troubleshooting when things go sour on an mostly and all-SMT build. I also like that it will be a four-layer board with mostly complete power planes in the middle. PIMETA v1.1c is already a great amp, and reducing the impedance on those signals should prove to help make a great amp even better. Another great thing is how there is a relatively clean layout despite how busy it is. It was quite neat how the previous iteration had the resistors and outputs all neatly lined up, but I'm a bit more biased to the layout-er's perspective given my first jump into board design. One thing I'd be wary of is the placement of C2A right next to OPAG. I'm guilty of not owning an opamp removal tool, so I've gotten used to grabbing the chip from the socket with my fingers and pushing my power caps off to the side slightly. I think there will be less tolerance for such behaviour with this new board. Nevertheless, that is still a really clever setup of the three capacitor slots, and there's always the possibility of using the scratchpad to even remove that problem from the previous board revision. I feel like I've said this before, but I'll say it again anyway. I really enjoy that there is the SMT option on account of beginners. After the CMoy, they can come to the PIMETA and have the option of building a substantially better amp either with SMT or through hole, extending the scope of learning available in this project. Some builders don't even get into SMT unless it's with something like an AlienDAC/BantamDAC, not a lot of the mainstream amps have SMT (they're probably more mainstream owing to that fact). I think it's a valuable bit of experience, and the sooner you can get into it, the better. Nevertheless, I think it's an excellent addition to an already great amp, and it will definitely be very valuable to the community on the beginner's front. I really like the layout in this board, tangent. We'll see how it stands up to the test run, but I'm quite certain it will fair very well. I'm excited to see the finished product. |
| tangent Headphone Council Joined: Aug. 27, 2001 | Message [#146] posted on: 03-19-2009 08:56 PM CST (US). | | I've tried a few different tools made for the purpose, and I don't like any of them. They give you too much leverage, or not enough control. It's just too easy to bend pins with them. What I use, and have found amazingly effective, is a simple right-angle pick:
The one I use doesn't quite fit in the trough of the socket under the chip, but the taper is so gentle that a little bit of a push lifts the chip a bit on that side, so right from the start it's lifting the chip. You could immediately move it to the other side, having loosened the one side. You have enough control to pry gently upward on the chip by pulling the handle away from the socket. A gentle move or two on each side, and it's easy to pull the chip out by hand. I've never significantly bent a pin this way. Especially helpful in this instance is that it's so slim, down away from the handle, that you can get it in almost anywhere. If you can get your fingers in somewhere to put the chip in in the first place, you can get the pick in afterward. I hadn't really thought about it, but yes, I guess it does give someone an unthreatening intro to the subject. You can always just give up on the SMDs and go thru-hole. The only mandatory SMDs are the buffers. No, even those are optional: you can jumper the buffer easily, by tying one side of R7 to the extra output pad. Thanks! Now we wait. In case someone's curious, while waiting, I'll be back on the YJPS finalization effort. I hope to get it buttoned up before the PIMETA v2 prototypes arrive. I'm not yet sure if I will do another proto run, or go straight to production. [Edited by tangent on 03-19-2009 at 08:57 PM.] |
| Mister X HeadWize Fanatic Joined: Jul. 23, 2003 | Message [#147] posted on: 03-20-2009 11:19 AM CST (US). | |
No need, looks like even 7343-28 and 7343-31 caps will be OK. |
| tangent Headphone Council Joined: Aug. 27, 2001 | Message [#148] posted on: 03-20-2009 04:01 PM CST (US). | | Don't forget that when using the RK097 knob, you want it to be centered on the front panel, which means the board doesn't rest in the lowest possible position in the case. Also, something I overlooked in this redesign is moving the RK097 pot forward a bit to allow the board to sit low and level inside the case. I expect PIMETA v2 to tilt upward toward the back end of the case, as PIMETA v1 does. This might get fixed in the production run, though. |
| kristleifur HeadWizer Joined: Apr. 10, 2006 | Message [#149] posted on: 03-21-2009 04:56 AM CST (US). | | I was thinking of doing a virtual-ground-less dual-rail PIMETA, to sate my curiosity and to have it serve as an occasional preamp. This is still possible with the v2, yes? |
| tangent Headphone Council Joined: Aug. 27, 2001 | Message [#150] posted on: 03-21-2009 09:45 AM CST (US). | | Sure, no problem. |
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