Pars

Happy Birthday!

A couple of Brother laser printers in here, as well as flash drives, etc.: Find a Best Buy on Weekly Deals & Sale Items - Buy.com

Someone said Tango IIRC

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From what I have seen in deemphasis is normally handled in the output stage. This is from the stock output stage of a Rotel 855. The FET (T401?) either turns on or off according to the DEEM signal, and shorts out the 5.6M resistor feeding the upper portion of the feedback loop (the bottom portion of 1.5k resistor and 2.4nf cap would be normal 1st order filter stuff for a TDA1541a). I've never looked at the DEEM signal to determine whether the FET is on or off normally, but I would assume it turns on if the preemphasis flag is set. All discrete stages I have seen ignore deemphasis. Mine uses a simple 1st order filter (1.5k resistor, 1.2nf cap). I've wondered whether I needed to do anything more, but believed that CDs using this were quite rare?

What Dusty sez! Happy Birthday!

Wishing you a speedy recovery!

Another thing that I am definitely going to use in mine is an e12 board... actually the modified one I did up awhile ago and use in my Dynalo. This one uses a 555 timer, but more importantly has a manual mute switch; nice for changing headphones without worries LED drivers/outputs for normal and mute/fault states option to tie fault test ground (pin 2 of the opamp) to the amp ground Most of you seem to be planning on doing balanced DynaFETs; the ability to deal with 4 channels (or more?) must be addressed if any are interested in this. Since this is Amb's design, even though more or less open source, it should be run past him to see if he objects. I suppose pairs of standard e12s would work for the most part also.

There's always Dantimax... Dantimax (elektronik) - Kits I should stay out of these discussions as I plan on my SE set to interchange with a Dynahi under construction, I already have case, pot, etc. and plan a very simple rear panel as this will only be a headamp.

The D5 in the part number means a DIN-5 connector, which is what the TTVJ pic and your Elpac pic use. Interesting that clicking on the datasheet link goest to iccus corp. who it appears bought elpac. Looking at the commercial lineup, I don't see the WM071 listed anymore, though it is in the WM.pdf datasheet still, but that is an Elpac datasheet. Doesn't bode well for commercial gear using this PSU unless it is an oversight.

Elpac only makes one linear +/-15Vdc wallwart IIRC: WM071-1950-D5 Now I suppose that TTVJ could have had Elpac do a custom version, but I would doubt it.

That is a pretty ugly casing job. The power connector is marked +/-15V, so I would think a DPS should work. If it is using the same Elpac (WM071 something) then the pinout would be the same. If you try it, I would check output DC offset before I plugged anything into it.

I would think that digikey or mouser should have it. Allied also has it, and has a 250' roll of Olympic clear jacketed on clearance: http://www.alliedelec.com/Search/SearchResults.aspx?Ntt=lamp+cord&N=4294965379&sid=11F6A430333A&Ntk=Primary 4th or 5th item down IIRC for $67

I've looked this over a bit more and here are the comments I have. In general my viewpoint is geared towards making the board more tolerant of any rework required down the road, hence comments regarding pad and trace sizings (bigger usually is more tolerant of desoldering, etc.) Trace width seems rather small on a lot of the circuits. Pad size also is small for the thru hole components, particularly on the larger resistors (2 ohm I assume?) up by the output FETs. But really, on all components. Trimpot pads are minuscule (and I realize those are the stock library sizing). I see you have vregs in place to allow for +/- 15V opamp operation (ala Dynahi). Hopefully, this circuit does not require higher voltage swing on the servo (hence the original opa445)? Overall, very nice job!

Damn, I must of missed that I may have to get one cuz I wasn't looking forward to dealing with steel for an IEC, etc. cutout.

Had a brief look at it and from what I saw, it looks good. It appears you have provisions for 0805 SMD, 0.200" and 0.300" resistors? For the I/O boards, these would I assume be mainly geared towards the balanced builds (certainly the SE->bal transformers )? This is probably for Naaman: What jacks do you normally use for both XLR and RCA on such boards? If it would be possible to do a board that would suffice for both SE and balanced builds, that would be greaaaatttttt. Not sure how plausible that is though. Also, the rear panels on the hifi2000 Pesante Dissipante cases are painted steel, which FPE won't work with. I would suggest shipping the 10mm front panels to them, and then designing an aluminum rear panel that they would supply? Otherwise, find some place that would work the steel panels.

Pete: You'd be doing it (or the builder). 0805 SMD is the size used on the PINT for example (and perhaps the mini3?). Small but not really hard to solder. Marc and/or Jacob: For an amp such as this, what advantages do you see in using SMD resistors? This isn't a high speed device (digital), so I wouldn't think that the shorter traces, etc, would be a huge advantage. Matching? Probably not. Marc: Have you found anyplace that you can buy reasonable quantities of either the KOA or the Susumu 0805s? I saw your thread asking about that in 2007.

I was planning on Roedersteins MK3s, and PRPs. I've always liked the BC (now Phoenix/Vishay) MRS and SFR series (0.4W and 0.6W), but only the 0.4W would fit a 0.2" spacing. I just replaced a pair of 100 ohm MRS on an I/V board with PRPs and could hear the difference (PRPs were better). So, being time to speak up, I am less than thrilled with this option. I know it tightens the layout up alot, but the tradeoffs are unacceptable to me. Tombstoning is not really acceptable either. Do you know of any really good 0805 resistors that aren't an arm and a leg pricewise? I know that some of the stepped atten. manufacturers think the resistors they are using are better than the leaded ones they used to use, but I haven't seen anyone identify what they are using.

Just noticed a problem on the schematic. Per post 72 in the headwize thread, only one of the two FB points for should be used. On the schematic here, both are being used. I would think using the point between the two 5k resistors would be best? [url=http://headwize.com/ubb/showpost.php?fnum=3&tid=6584&pid=59968&fpage=4]HeadWize: View Post [DIY Workshop

Looks good. I assume that is ground plane (top) that is not rendered? What are the resistor package sizes? I guess I assumed when Marc (luvdunhill) asked for the 0.200" and 0805 SMD, that these would be in addition to an RN60D type footprint... guess not. That's alot of money to Texas Components... My only other comment at this point would be that it is my preference for an input connector that it be a Molex KK 0.100 rather than the Phoenix blocks, but that is minor. I would assume that the mounting holes match a Dynahi board, as well as the output device mounting holes? I measured 0.45" c-to-c on the output devices on a Dynahi board I had. Mounting holes were 4 9/16" and 3.5" c-to-c. You're pretty fast with Eagle, aren't you I was trying to recreate your previous layout this weekend and only got about halfway done with it. And was glad I didn't have to determine component placement...

BTW, Charles Hansen has been noting some interesting observations on MOSFETs: DIYHiFi.org • View topic - push and pull me back into the limelight

Yeah, I hear you. Marc: Your analogy to power amps should probably be change to preamp as a closer fit in terms of noise performance. But yes, I would think with a shielded trafo (or perhaps use of a split bobbin instead of a toroid) that single box should be fine. My dynalo (V2 headamp board) has an unshielded Amveco in there that was supposed to be mounted on the board (not a PCB trafo though). Mine is just off the board and I don't hear noise thru it. Granted, I dont have any IEMs to check it with.

No. The original Gilmore dynamic (i.e., dynalo) used a +/- 16.4V PSU, which is probably what your Gilmore Reference uses. The Dynahi, etc. use +/- 30V PSUs. One other thing regarding the boards. The offset adjustment pots present on the Dynahi were not in the DynaFET schematic, nor on the board layouts that I have seen (though I could hav missed them). The pots were present on the google spreadsheet BOM however. The (2) 500 ohm resistors should be replaced with 620 ohm with a 10K pot in parallel with each.

Yeah, I hope you make it home safely and get checked out in the hospital with no problems. Take care!