Pars

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Pars last won the day on February 27 2013

Pars had the most liked content!

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About Pars

  • Rank
    High Roller
  • Birthday 05/16/1954

Profile Information

  • Gender
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Converted

  • Location
    Chicago
  • Occupation
    engineer (telecom mktg)
  • Hobbies
    golf, music, cycling
  • Headphones
    AKG K601, Shure SRH840, Modded Fostex T50RP
  • Headphone Amps
    Gilmore dynamic (headamp v2 PCB), Dynahi (still proto stage)
  • Sources
    � Rotel RCD-855 modified (clocking, discrete output stage) � Rotel RCD-991 THS4031 I/V, AD8599 buffers
  • Other Audio Gear
    ? maybe Classe preamp, Odyssey Stratos poweramp, Von Schweikert VR4 Gen.II speakers

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  1. Dontcha love marketing? I was laughing reading some of the article titles and thinking how self-serving these were "Television Replaced With Black Gates is Superior to Any Ordinary TVs"... I didn't realize you could watch blackgates?
  2. Of course the 2nd board was too good to be true. Put the 2nd pair of outputs in, oscillating to beat hell now without volume up, nothing plugged in. 70+MHz (0.7 div @ 0.2us/div). Board was acting strange even before I powered it (wasn't even plugged into AC). When I put the scope probe on the R output, it showed some fuzz on the trace. Board was plugged into all I/O. Strange. When powered, the oscillation was independent of volume setting, and with no phones plugged in. Varied at times by just approaching the bench, moving hands, etc. Fun. I'm going to try Cordell's zobels on this one first. Probably use some 100pf Wima FKPs I have with 90.9R or 120 or 150 ohms to gnd. Or I have some 33pf Mica caps. Also had noticed that I hadn't gotten the devices all the way onto the angle brackets (drilled like my dynahi ones), and recalled getting pissed at not being able to accurately hit a good center punch (Starrett) dimple with my drill press, so bought some cheap center bits from Harbor Freight. Redrilled the angle bracket for the good channel. Much better. I'll redo the other one presently. Also discovered my load box is broken; Lorlin rotary switch wasn't working correctly.
  3. Happy Birthday Naaman!
  4. RIP Bill Paxton... http://www.cnn.com/2017/02/26/entertainment/bill-paxton-dead/index.html?adkey=b Wow... 61 way too young.
  5. Speaking of older electrostats, anyone recall the Marantz ones from the '70s, ES1 or something like that? My brother and I used to have a set; he may still have them. Were these any good? I can't say I recall being impressed with them.
  6. Not running any load right now, just straight into an maudio fw box. I do have a load box from tangent's plans (https://tangentsoft.net/audio/hp-dummy.html ) that I could toss on there. It has 33, 330 and I can't recall what else on it. EDIT: it has input and output jacks on it. Its been so long since I built it and used it that I forgot what all is on it
  7. Ran RMAA on the 1st board (R ch). Everything looked fine. Re-ran it with the output zobel on, looked about the same, so my conclusion is it is working. I think for safety I will put on zobels ala Cordell. Need to find a near enough ground on the bottom. Set up the 2nd board with one pair of output devices. It biased right up, offset adjusted and looks good. I could not get this one to oscillate. No zobels or anything other than the stock configuration that I've settled on. I'll document what that is later. I'll add the 2nd pair of output devices and see what happens then. RightMark Audio Analyzer test : Dynahi-L DynaFET-R.pdf
  8. Looks nice Michael! Only a 25VA transformer? I guess it is 700mA per secondary,
  9. Started working on the other board last night, re-configuring it to match the first. I plan on bringing this up without the ferrite beads, but add the gate zobels to it, which I haven't tried yet. These seem more like a snubber than a zobel (cap -> resistor -> gnd). Cordell uses 39pf -> 100R; I don't have any 39pf but do have 33pf, so will probably increase the resistor a bit (120 or 150). The one Cordell uses seems to sim out at -3dB of > 10MHz. I may increase the cap to 100pf, but I'll try it with the 33pf first. I'll report back on how this behaves without the ferrites. I also plan on running RMAA on the first board, with a Dynahi board in the other channel. If things look amiss, or even if not, I will re-run this with the Amb zobel on the output and see what that looks like. If that looks better/different, I may put the Cordell zobels on this board and see what that looks like.
  10. I would. Lately, orders from Arrow have been using fairly large antistat bags for everything. You can also buy them with ziploc-type closures. Places like OfficeMax or staples carry them I believe. Sent from my iPhone using Tapatalk
  11. The best way that I have found is to use heavy stock and number in rows. I use 3M double sided tape to stick the devices on, then put it in an antistat bag. Add the measurement key, or just have that in a spreadsheet. Sent from my iPhone using Tapatalk
  12. Brave man plugging good phones in [emoji4] The ones I am using are real crap Sony something or other. $5 and you overpaid... I would bet that the output zobel would take care of that for sure, the gate zobel (Cordell) probably, and the ferrites probably. Some people do quite involved zobels with inductors etc. from gate to drain. Sent from my iPhone using Tapatalk
  13. Ahh, so that's what the software is for... now onto the maths! Very cool!
  14. One other thing, some of the transistors in the diamond buffer section are running quite warm: Q26, Q23, Q18 and Q17 (purple ovals). Q26 is running ~60*C, and this is open air. I have some of the EDM sinks, but they push the transistor leads closer together than I like them. I also have some To92 heat sinks that I might try. DynaFET_schematic_marked.pdf
  15. Katz may be very successful and experienced, but I've never heard of him, other than innerfidelity. Then again, I don't really listen to jazz, which going back to his reference recordings, seems to be where he exists. This isn't the first of his articles that I have read; guess he's just not my cup of tea. My undergrad is in music (percussion performance) and I spent quite a bit of time playing with symphony orchestras. I'm well aware that different examples of the same acoustic instrument sound different. My idea of a natural sounding recording would be this one, which in my opinion (and my brother's (trumpet)), is a recording that sounds to both of us like the CSO in orchestra hall, back when they had a phenomenal brass section (Herseth/Jacobs, et. al.). That said, I would rather listen to a so-so recording of a great performance than a SOTA recording of a so-so performance.