spritzer Posted April 18, 2015 Author Report Share Posted April 18, 2015 (edited) The transformer will add noise. Only way around that is to switch to an R-core and isolate it. Won't be perfect but it will help. Edited April 18, 2015 by spritzer Quote Link to comment Share on other sites More sharing options...
sorenb Posted April 27, 2015 Report Share Posted April 27, 2015 Finished two sets of Dynalo this weekend and two sigma22 psu's. The offset seems to drift a lot; without the servo's it's within a range of 40mV on all boards - fluktuate the full range within a couple of min or so.With the servo in place it's within a range of 0,5mV Is that normal behavoir? Using +/- 18V for rails I get approx 22-28mA through the output transistors across the four boards. Would that be running those trans too hard? should I lower r38/39? Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted April 27, 2015 Report Share Posted April 27, 2015 yep, wave a piece of paper over it, the thermals change and the offset drifts. for 18v rails, that is a good current. Quote Link to comment Share on other sites More sharing options...
sorenb Posted April 27, 2015 Report Share Posted April 27, 2015 Ok. I'll leave them as is, and give a listen to hear wheather the effort was worth it ( I guess it was ;-) Many, many thanks Kevin for making and sharing your design. Also thanks to Spritzer, mypasswordis, GrindingThud, gepardcv, Pars, JimL, mwl168, and others sharing/contributing to the thread. Pics, or i didn't happen: Quote Link to comment Share on other sites More sharing options...
UFN Posted April 27, 2015 Report Share Posted April 27, 2015 Looks good! Still haven't actually powered mine up - must get round to that soon... //UFN Quote Link to comment Share on other sites More sharing options...
Pars Posted April 27, 2015 Report Share Posted April 27, 2015 Finished two sets of Dynalo this weekend and two sigma22 psu's. The offset seems to drift a lot; without the servo's it's within a range of 40mV on all boards - fluktuate the full range within a couple of min or so.With the servo in place it's within a range of 0,5mV Is that normal behavoir? Using +/- 18V for rails I get approx 22-28mA through the output transistors across the four boards. Would that be running those trans too hard? should I lower r38/39? Did you have the inputs grounded for this? Mine was < +/- 5mV, normally +/- 2mV without the servos in place. Quote Link to comment Share on other sites More sharing options...
sorenb Posted April 28, 2015 Report Share Posted April 28, 2015 Did you have the inputs grounded for this? Mine was < +/- 5mV, normally +/- 2mV without the servos in place. good one Pars ) No, did my measurement with open input .... inputs grounded its within 4mV (+O - -O) I haven't put the servos back in, but spend some time listning. My Sennheiser HD800 have never sounded better ) Done my listning using my Tact Mill. mkIII, and the Dynalo is clearly better than hooking up the HD800 directly to the speaker terminals ....much better. Thnx Kevin and Pars! Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted April 28, 2015 Report Share Posted April 28, 2015 its definitely my favorite amp for hd800 not even close. yep offset currents open input cause trouble. Quote Link to comment Share on other sites More sharing options...
nopants Posted May 4, 2015 Report Share Posted May 4, 2015 For those using the haa15 supply, is it possible to remove the transformer+board from the metal on which it's mounted? I have a case but it's only 2in tall- the sheet lists the height as 2.1 Quote Link to comment Share on other sites More sharing options...
gepardcv Posted May 4, 2015 Report Share Posted May 4, 2015 The transformer is just held in place with four bolts, should be easy enough. The board might be trickier. The Mouser picture shows the bottom accurately, and I'm not sure how to remove and replace the two metal pieces on the bottom. Not sure what they are, actually. Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted May 4, 2015 Report Share Posted May 4, 2015 (edited) the pass transistors go thru the bottom, so you would have to remount them on the new chassis the transformer is 2.04 inches, so the 2.1 inches is right Edited May 4, 2015 by kevin gilmore Quote Link to comment Share on other sites More sharing options...
Pars Posted May 5, 2015 Report Share Posted May 5, 2015 (edited) Wasn't sure where to put this, so here seemed fine, though applicable to a bunch of amps here. Balanced-SE input jack board with switch. I was playing around in Eagle (after having to manually wire one of these up). This is set up to use either a 4PDT switch (for isolating all 4 signals) or a 2PDT if you only want to switch the - signals to ground for SE, but leave the + signals connected to the RCA jacks. Pads are provided to connect RCAs. I haven't verified the heights of the Neutrik NC3FAV jacks versus the switch height. My goal would be to have the board mounted to the faceplate via the Neutrik jacks only, with the switch sitting behind the faceplate and the toggle only extending through a slot. Might need a standoff or two as well. Switches this is designed for are the NKK M2042 (633-M2042SS1G03) 4PDT or M2022 (633-M2022SS1G03) DPDT. Board outputs are set up for either Molex 0.100 KK connectors, or you could use the pads as wirepads and solder the wiring in. I know Birgir has a balanced input jack board, but his is for including a pass-through connection, and not for balanced and SE. Any comments welcome. Edited May 5, 2015 by Pars 1 Quote Link to comment Share on other sites More sharing options...
Kerry Posted May 5, 2015 Report Share Posted May 5, 2015 (edited) Looks nice. You might want to switch the output connectors to the back side of the board. If I understand it correctly, the inputs and switch face the back side of the amp and the outputs would face inside the amp. Edited May 5, 2015 by Kerry Quote Link to comment Share on other sites More sharing options...
Pars Posted May 6, 2015 Report Share Posted May 6, 2015 (edited) Kerry, Thanks for the comments. Actually, the Neutrik XLRs and the switch are on the back side of the board. The Molex connectors are on the front. The switch is intended to protrude through the back panel (slot). As I mentioned, I haven't checked the mounted heights of the XLRs vs. the switch to see how that would work out. And for support, it might need a standoff or two on the back side. EDIT: Actually you are right in that the XLRs were drawn from a front perspective. Corrected now (not in image above). Edited May 6, 2015 by Pars Quote Link to comment Share on other sites More sharing options...
sorenb Posted May 7, 2015 Report Share Posted May 7, 2015 Having read the SRX-revisited thread by JimL and the referenced articles by W.Jung I decided to replace the current sources in the one Dynalo I've built. From the 1st article by Jung, it seems as if that the CCS design used in the Dynalo has indeed a very good performance. However as JimL has pointed out the cascoded CCSs seems to offer even better performance. Looking at the very simple LM334 with one resistor demonstrates 20db better rejection than the LED CCS although the performance rapidly degrades past 10kHz; the cascoded LM344/2N5486 however maintain the performance above 10kHz. So, based on that I decided to try it out. First I have implemented the non cascoded LM334. At first hand it sounds like an improvement. However, not night and day difference; the sound is a bit more refined/detailed, and the soundstage as gained a bit more depth. Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted May 7, 2015 Report Share Posted May 7, 2015 (edited) the current sources see the tails of the differential inputs. So really its very close to a dc level that does not change with input signal. maybe microvolts if that much, so the current sources really have very little difference. changing the current sources may change the current a bit which changes the output stage current, so you may be hearing that. Edited May 7, 2015 by kevin gilmore Quote Link to comment Share on other sites More sharing options...
sorenb Posted May 7, 2015 Report Share Posted May 7, 2015 Can't argue that, and you may be right, that it is rather the change in current than the CCS itself that I am hearing Though I did try to match the existing current as close as possible. Anyway part of the fun doing DIY is also trying out stuff, and maybe realize that it didn't matter that much. For now In rgrds to the current in the output stage I haven't seen you recommend a sweetspot, other than commenting that one might 'get away' with 18mA ...is 18mA the sweet spot ? Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted May 7, 2015 Report Share Posted May 7, 2015 for the surface mount version which can handle a bit more heat, 20ma per transistor 160ma on each rail per board Quote Link to comment Share on other sites More sharing options...
nopants Posted May 7, 2015 Report Share Posted May 7, 2015 Is the SMD version in sync with the through hole version? I've been reading about regulators and this looks like a nice platform to conduct some tests with the power supply side of things Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted May 7, 2015 Report Share Posted May 7, 2015 identical. pzta56 silicon exactly the same as mpsw56 only difference is package and heatsinking the silicon to the tab Quote Link to comment Share on other sites More sharing options...
nopants Posted May 8, 2015 Report Share Posted May 8, 2015 Sorry I was referring to the PCB not the part. I'm probably going to put in an order to Bay Area Circuits soon Quote Link to comment Share on other sites More sharing options...
sorenb Posted May 8, 2015 Report Share Posted May 8, 2015 @nopants, can I ask to join your PCB buy for Dynalo SMD? @Kevin: whats your opinion on adding a degenerated current-mirror to the input stage? Quote Link to comment Share on other sites More sharing options...
nopants Posted May 8, 2015 Report Share Posted May 8, 2015 I found boards, and even if I was doing my own I would have only gotten 2 or 3 boards, literally Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted May 8, 2015 Report Share Posted May 8, 2015 kgdynalobal7 is the all surface mount version. no one that I know of has made this one yet, so maybe check for errors. will look at the current mirror later, but the board would probably have to get bigger as its stuffed. Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted May 8, 2015 Report Share Posted May 8, 2015 finally updating my test equipment... with a 30db attenuator and 50 ohm load... http://gilmore.chem.northwestern.edu/ssdynalobalthd.jpg surprisingly close to my 30+ year old antique Quote Link to comment Share on other sites More sharing options...
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