arthurli Posted February 9, 2022 Report Share Posted February 9, 2022 Kevin, Apart the input device That 340 , do we need match the transistors? If use jets input like 2sk170 and j74, are there any change to the resistor values of the input stage circuitry? Thanks Quote Link to comment Share on other sites More sharing options...
Pars Posted February 9, 2022 Report Share Posted February 9, 2022 You might try reading the thread before asking questions... Quote Link to comment Share on other sites More sharing options...
JGergo Posted February 16, 2022 Report Share Posted February 16, 2022 On 1/11/2022 at 5:09 PM, Pars said: Would there be any problems with using BC556B parts with BC546C? Both On-Semi? I'd be buying 100 of each. Vendor doesn't have the 546B parts in stock (on-semi). If this question is still relevant, try TME, they have the OnSemi 546B on stock Quote Link to comment Share on other sites More sharing options...
JGergo Posted February 17, 2022 Report Share Posted February 17, 2022 On 2/7/2022 at 2:05 PM, kevin gilmore said: so split versions of the cfa3 board. stack the boards together and put on the heatsink (minimum heatsink vertical dimension 83mm) stack the boards together, use angle bracket mount horizontally for low profile chassis etc cfp3smt2splitamp - CADCAM.ZIP 61.71 kB · 24 downloads cfp3smt2splitpre - CADCAM.ZIP 77.07 kB · 26 downloads Do I assume it correctly, that the pre board is intended to be flipped along the Vcc axis in order to have the 3way posts aligned on the same side with the shortest possible connections? Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted February 17, 2022 Author Report Share Posted February 17, 2022 that is one of the ways of building it. Quote Link to comment Share on other sites More sharing options...
RudeWolf Posted February 17, 2022 Report Share Posted February 17, 2022 On 3/26/2021 at 3:04 AM, Kerry said: Work in progress... I should be able to test soon 🤞 Did this make through the testing? I love doing smt just to spite people! Quote Link to comment Share on other sites More sharing options...
Kerry Posted February 17, 2022 Report Share Posted February 17, 2022 I've been pulled away from this to launch our Aeras e-stat amp, but will be getting back on this after the launch. SMD is not done to spite people I'm trying to meet get specific size requirements and it seems to be the way the world is going. 2 Quote Link to comment Share on other sites More sharing options...
audiostar Posted February 17, 2022 Report Share Posted February 17, 2022 6 minutes ago, Kerry said: I've been pulled away from this to launch our Aeras e-stat amp, but will be getting back on this after the launch. Hey Kerry, what is the Aeras e-stat amp? Quote Link to comment Share on other sites More sharing options...
Kerry Posted February 17, 2022 Report Share Posted February 17, 2022 I'm launching a new company and this is our first product. Here's the announcement: 9 Quote Link to comment Share on other sites More sharing options...
audiostar Posted March 13, 2022 Report Share Posted March 13, 2022 Look what the cat just dragged in 🙂 1 Quote Link to comment Share on other sites More sharing options...
audiostar Posted March 13, 2022 Report Share Posted March 13, 2022 Prior I start desoldering any components from my other boards, I thought I'll ask if anyone might need two fully populated (except Opamps and JFETs) wider boards. Not trying to make any profit, will sell at BOM cost, DM me if interested. Those have never been powered up, build to specs, MJF devices tightened to 0.8Nm using stainless steel hardware, 105°C Panasonic FR electrolytics and WIMA/Kemet/Murata caps used as well as Bourns 3296W trimpots and Mill-Max IC sockets. All BC556B/BC546B onsemi devices were selected from 100 and are matched to Idsss. Quote Link to comment Share on other sites More sharing options...
Helium Posted March 13, 2022 Report Share Posted March 13, 2022 If not sold, are you going to transfer most components to split boards? Out of curiosity, are split boards so much better than wider boards to justify hard work of desoldering and soldering a lot of parts? Quote Link to comment Share on other sites More sharing options...
audiostar Posted March 13, 2022 Report Share Posted March 13, 2022 1 hour ago, Helium said: If not sold, are you going to transfer most components to split boards? Out of curiosity, are split boards so much better than wider boards to justify hard work of desoldering and soldering a lot of parts? To be honest the only reason for me moving to split boards is pure cosmetics, because I can fit them better in my case which is taller but same 32cm width as my external dual GRLV PSU. If I was going to use a standard 43cm case I would not switch, no reason to. Originally I planned to use the wider boards in the same case with the left board on top and upside down and right board on bottom, leaving space in the middle for the rod coming from the back where the input selector board would be holding the pot as well. But this is not as nice as using the split boards. I would not move everything, probably only the MJF devices, the Bourns trimpots, some caps and maybe the 1R CMF resistors. Quote Link to comment Share on other sites More sharing options...
audiostar Posted March 13, 2022 Report Share Posted March 13, 2022 @kevin gilmore would there be any benefit in using low inductance resistors like Caddock or Fukushima MPC74 for the 1 ohm resistors? Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted March 13, 2022 Author Report Share Posted March 13, 2022 the inductance is going to be really low in any case. 1 Quote Link to comment Share on other sites More sharing options...
audiostar Posted March 16, 2022 Report Share Posted March 16, 2022 Has anyone any adapter boards left or gerbers for using 2SJ109/2SK389 in the 14-pin JFET socket? I am sure I was looking somewhere at these, unfortunately can't find anymore. Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted March 17, 2022 Author Report Share Posted March 17, 2022 there are gerbers for the k489/j689 and the 2sc3381/2sa1349 pretty sure the 2sj109/2sk389 is compatable with the 2sc3381/2sa1349 board you are looking for that340.zip 1 Quote Link to comment Share on other sites More sharing options...
Pars Posted March 17, 2022 Report Share Posted March 17, 2022 Kevin, The pinout of the bipolars is not compatible with the 2sj109/2sk389. I did boards for those and can supply the gerbers. They should also be in one of the dynalo, etc. group buys that Steve ran (sbeylo) some time ago. 1 Quote Link to comment Share on other sites More sharing options...
audiostar Posted March 17, 2022 Report Share Posted March 17, 2022 (edited) Thanks, Kevin, found it. The pinout for the 2SA1349/2SC3381 do not line up with 2SJ109/2SK389 though, despite being the same package. Will make a new one and post it. 5 minutes ago, Pars said: The pinout of the bipolars is not compatible with the 2sj109/2sk389. I did boards for those and can supply the gerbers. They should also be in one of the dynalo, etc. group buys that Steve ran (sbeylo) some time ago. Great, Pars. Could you please post here. Thanks mucho! Edited March 17, 2022 by audiostar Quote Link to comment Share on other sites More sharing options...
Pars Posted March 17, 2022 Report Share Posted March 17, 2022 Here they are. THAT340-J109-K389-JFET.zip 2 Quote Link to comment Share on other sites More sharing options...
audiostar Posted March 29, 2022 Report Share Posted March 29, 2022 On 3/17/2022 at 2:09 AM, Pars said: Here they are. Thanks, Pars! Which pins are you using on the lower side, that go into the 14-pin socket, do you have the p/n handy? Thx Quote Link to comment Share on other sites More sharing options...
Pars Posted March 29, 2022 Report Share Posted March 29, 2022 (edited) I actually got them from ebay. I think Kevin had posted a link in one of the threads, probably the Dynalo thread. Ebay isn't showing me who or what these are (only goes back to 2020 purchases). I'll keep looking. EDIT: it was something like these: https://www.ebay.com/itm/254636284745?hash=item3b49815b49:g:CGIAAOSw8s1gnfky Edited March 29, 2022 by Pars 1 Quote Link to comment Share on other sites More sharing options...
ang728 Posted March 29, 2022 Report Share Posted March 29, 2022 49 minutes ago, audiostar said: Thanks, Pars! Which pins are you using on the lower side, that go into the 14-pin socket, do you have the p/n handy? Thx the pin header I use is 127-1-4010-8002-310 made by Nextron. Or you can search "Nextron 2.54mm round pin" on Ebay 2 Quote Link to comment Share on other sites More sharing options...
audiostar Posted March 29, 2022 Report Share Posted March 29, 2022 (edited) Thanks, guys! I am looking for something that is not too long and does not stick out too much of the IC socket. Also most of the pins I got are square. Edited March 29, 2022 by audiostar Quote Link to comment Share on other sites More sharing options...
audiostar Posted April 3, 2022 Report Share Posted April 3, 2022 (edited) On 11/29/2017 at 7:50 PM, kevin gilmore said: Newest version of the current feedback amplifier with the servo not in the audio circuit so that you can use cheaper opamps. But if you run 30v, you still need 30v capable opamp. Like opa551. what the noise difference if any, I don't know yet. I was checking old messages in the thread and found this. As I am running 30V dual GRLVs (with the new split boards), do I need to change from standard OPA445 to OPA551? Looks like... still not powered on for the first time. Looking through the specs, the OPA445 goes indeed up to 45V, confused. Edited April 3, 2022 by audiostar Quote Link to comment Share on other sites More sharing options...
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