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tomb  Headphone Council Joined: Mar. 1, 2006 |  Message [#60] posted on: 10-17-2006 11:17 AM CST (US).   |  |  The 5-pin BUF634 is a TO-220 version, and is often available at the same sources as the DIP-8 version. Pete Millett's original Millett used TO-220 BUF634. That was all before we knew they didn't pull that much power in headphone amps. Peak current - yes, but not constant. A DIP-8 case only gets mildly warm, even when biased into Class A, as in the PIMETA. I would love to see this produced with DIP-8 sockets, so that we could stack the buffers (said that a few times already |
gewa HeadWizer Joined: Sep. 22, 2006 | Message [#61] posted on: 10-17-2006 12:32 PM CST (US). | |
Thanks. I can always ask digi01 to help us out with this.
I once got them from RS. (236-8572) Attached 2 other designs. The DIL version is 35mm wide and therefore will touch C8. And now a question from me! Would it be insane to use a BG-N for C1 and C13? Regards Attachment: C2165.jpg,C2166.jpg |
| jtbarclay Member Joined: Aug. 1, 2006 | Message [#62] posted on: 10-17-2006 03:47 PM CST (US). | | Just wanted to know a few things that beeah used, what are those blue terminals called and where can I get some? Also what is the difference between the little square caps and the big orange ones? P.S. Digi01 clear your inbox it is full... |
beeah Member Joined: May 17, 2006 | Message [#63] posted on: 10-17-2006 04:40 PM CST (US). | |
The blue things are called terminal blocks, IIRC - I got them at Radio Shack, along with a whole mess of other parts in the picture (a local RS store went under, and I waited until the prices got ridiculously low and bought a whole mess of parts that I thought might come in handy some day...  ).The little square caps are Wima MKP, either metallized polypropylene or pp film & foils. They're so small, in fact, that the leads barely reach the closest opposing holes. If you look closely you can see that they lean a little bit due to the lead being bent and protruding out the side rather than straight down. The big orange ones are film & foils known as "orange drops", and are larger due to their higher voltage capacity and different construction. Both are available through various DIY vendors as well as through Mouser. While some might debate the fact, both are fairly neutral caps that don't have much of a sound of their own (a good thing) and are well suited to a simple app such as the SOHA. I have some in expensive Dayton film & foils in my junk box that I might try in place of the Wimas. Bottom line is that the sky's the limit as to how much you can spend on coupling caps - the limiting factors are what will fit the board (and your wallet). |
| tomb Headphone Council Joined: Mar. 1, 2006 | Message [#64] posted on: 10-17-2006 04:58 PM CST (US). | | Gewa, Outstanding little boards! I'll take 10. (Is there room for a bandwidth resistor for the Buffers?) |
Ferrari HeadWizer Joined: Apr. 29, 2006 | Message [#65] posted on: 10-17-2006 05:14 PM CST (US). | | [quote ... And now a question from me! Would it be insane to use a BG-N for C1 and C13? Regards I use BG-NX for C1 and C13 on my one SOHA without any regret. |
| paladinman HeadWizer Joined: N/A | Message [#66] posted on: 10-17-2006 07:30 PM CST (US). | | I recently bought these boards. Someone mentioned earlier that BOMs would be put up for digi, mouser, etc. Does anyone have a BOM for digi that based off 'standard' specs. That would be great--else, i guess I might end up making one. |
| stevodude Member Joined: Oct. 9, 2006 | Message [#67] posted on: 10-17-2006 08:12 PM CST (US). | | damn you headwize for making me spend money :-) hehehe anyway, built my cmoy last week, but just not quite what I want, so I'm going to build a soha/stoopid. I've almost got a complet BOM list from mouser - minus a vouple of components I'll get locally, but total cost is going to be a little bit more than I anticipated. Has anyone done a BOM with components sources from australia? if not I'll have to order from mouser I spose. Cheers, looking forward to the challenge. |
| gewa HeadWizer Joined: Sep. 22, 2006 | Message [#68] posted on: 10-18-2006 06:19 AM CST (US). | |
Hold your horses tomb!  If digi01 is prepared to have them manufactured I will supply him with the necessary files because I simply don't have the time to organize and handle GB's.
That won't be a big problem. Either through hole or smd is possible on all the boards. Depending on the type of resistor the PCB will slightly increase in size, but not much. Let's wait and see what people need, or want, to get a final design up. Or a scored board with a couple of each design, to keep everybody satisfied. Regards |
| tomb Headphone Council Joined: Mar. 1, 2006 | Message [#69] posted on: 10-18-2006 10:36 AM CST (US). | | Gewa, Didn't scare you, did I? |
| rreynol Member Joined: Oct. 13, 2005 | Message [#70] posted on: 10-18-2006 12:47 PM CST (US). | | On a similar note, here's a layout I've been playing with for a similar adaptor board. I'm new to Eagle and PCB making in general so who knows if i'll ever have some protos made. |
| gewa HeadWizer Joined: Sep. 22, 2006 | Message [#71] posted on: 10-18-2006 02:18 PM CST (US). | |
Not scared, a bit surprised
Well we all have to start somewhere. Once you get the hang of it everything will work out fine. Try to avoid 90° bends of the traces and start with the power supply traces first. Attached are three rouch versions with the bandwidth resistors. On a sidenote; MY BOARDS ARRIVED! Regards [Edited by gewa on 10-18-2006 at 02:22 PM.] |
| gewa HeadWizer Joined: Sep. 22, 2006 | Message [#72] posted on: 10-18-2006 02:23 PM CST (US). | | Euuh...here they are [Edited by gewa on 10-18-2006 at 02:25 PM.] Attachment: C2173.jpg,C2171.jpg,C2172.jpg |
digi01 HeadWize Fanatic Joined: Dec. 3, 2002 | Message [#73] posted on: 10-18-2006 07:21 PM CST (US). | | gewa, they are smart design!thank you  would you like to have them manufactured by me?I have 2 solid buffer design,so I can make them together as a group buy. P.S. Zang |
| tomb Headphone Council Joined: Mar. 1, 2006 | Message [#74] posted on: 10-18-2006 09:15 PM CST (US). | | Gewa's little boards look great, Digi - count me in on a Group Buy. |
GregVDS HeadWizer Joined: Oct. 25, 2005 | Message [#75] posted on: 10-19-2006 02:26 AM CST (US). | | rreynol, I had something like this in mind, but my case will be so tight I was planning to have the four IC touching each other. I should try to design this into Eagle too. Did you find the buf634 and opa627 in Eagle libraries? What is the use of the bandwidth resistors? All the best, GregVDS ps Digi01, please, wait somehow to produce IC buffer board, as there are a lot of design at the mo, and no consensus at all. All the very best, GregVDS |
| digi01 HeadWize Fanatic Joined: Dec. 3, 2002 | Message [#76] posted on: 10-19-2006 03:21 AM CST (US). | | I have draft a layout based gewa's design. [Edited by digi01 on 10-20-2006 at 03:44 AM.] Attachment: C2177.pdf,C2175.GIF |
| gewa HeadWizer Joined: Sep. 22, 2006 | Message [#77] posted on: 10-19-2006 05:34 AM CST (US). | | digi01
Thanks Zang. Tonight I'm going to try to make them even a bit smaller.
Yes ofcoarse!!
If you don't mind,yes please. GregVDS I will see if I can get a design done for the use of OPA's Regards |
| kristleifur HeadWizer Joined: Apr. 10, 2006 | Message [#78] posted on: 10-19-2006 05:56 AM CST (US). | |
They make the BUF634s a) use more current, and b) sound better. (I'm not sure, but I believe that it's similar in principle to biasing opamps into class A.) An overview can be found in the Pimeta documentation: |
| GregVDS HeadWizer Joined: Oct. 25, 2005 | Message [#79] posted on: 10-19-2006 06:01 AM CST (US). | | thanks, My SOHA is already soldered, and I don't plan to desolder things. I would like to know if the standard power supply will suffice for two OPA627, two BUF634 (dip8 ) stuffed with those bandwidth resistors? I feel it will depend the value of the resistors, right? Hence this one: What value for the resistors would be ok to use without blowing the power supply parts? All the best, GregVDS [Edited by GregVDS on 10-19-2006 at 06:02 AM.] |
| tomb Headphone Council Joined: Mar. 1, 2006 | Message [#80] posted on: 10-19-2006 06:33 AM CST (US). | | Several things guys: 1. My preference is for Gewa's BUF634 DIP-8 version. Those are much easier to use in many different amps - Millett, PIMETA, etc. Not able to afford dozens of BUF634's, I regularly transfer one stack to the other during multiple build-ups. It works great, but that would obviously be difficult (impossible) with the TO-220 version. 2. A Brown Dog adpater to utilize two single opamps for the dual opamp socket will fit right over a pair of stacked BUF634's. That is the same method used in a PIMETA for OPA627's and stacked BUF634's. Even so, stacking an extra DIP-8 socket underneath the Brown Dog should take care of any concern with clearance. We should probably not implement a two-single opamp layout, since the Brown Dogs are so readily available. 3. Gewa is partly right about the bandwidth resistors. However, the ratio is inversely proportional to 200ohms/BUF634. Here is what Tangent says:
So, one buffer - 200 ohms, 2 stacked buffers - 100 ohm (per channel, of course). Too much resistance, and the current is reduced. Lesser resistance will not increase the current after that, but will introduce distortion. BUF634's without bandwidth resistors are not optimum. That is the important conclusion. Greg: [Edited by tomb on 10-19-2006 at 06:34 AM.] |
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