These guys? I don't think they're even being made any more. They date from when transistors cost much more than tubes.
My last projects have been quick and painless. I am always seeing various components in our local Goodwill store. Some just need some TLC, polishing and cabinet work. One component just seems to surface over and over, the little Sony DVD/CD player, an inexpensive little unit, but sounds very nice, so I decided to sand that top and give it a mirror Steinway black top, it just dressed up so nice! My other small project was a Marantz receiver, with lots of surface scratches. I used some really great car poslish and now look at it, good as new, small projects but fun to tackle. The polishing on the side wings of the Marantz piece, gave it a gloss finish, much like the Sony piece above, both turned out so nice and work beautifully in a small bedroom system. The Sony was I believe $4 and the Marantz $19
4 B4 C7 DFB D04 F 4 BDE 8853 C939 EC419475 — Postimages Above is the link to my tweaked spare Xerxes top board featured earlier on page 5 of this thread being filled and repainted, now fitted to my deck. I fitted my Rega RB300 as it was sat on the shelf with cartridge fitted and is so easy to slot in. I know from experience that if I can get my Rega arm to perform well that my Tabriz arm will perform even better when it replaces the Rega arm.....usually! This is the first time I have had a Xerxes arm board with no sag. The first thing I noticed is that the Xerxes outer platter is riding about a millimetre higher than before. This in turn meant that the Rega arm was a fraction too low at the rear reducing VTA. This rolled off the highs a bit making SQ harder to assess. No matter, I could just insert a 1 MM shim, but my local dealer only had a 2mm minimum shim at £10. My favourite hardware store had bags of assorted copper washers for only £3.99. As luck would have it the largest copper washer in the pack is just the right width and only 1.31 MM thick, perfect for the correct VTA or near as dam it! So what does it sound like? Well filler, even high performance wood filler is not wood. The sound had a slightly muted or closed in upper frequency over the standard all MDF board. I fitted a mass damper which is screwed into the underside of the board mid point between the main bearing and the start of the cut out slot to the arm side. It is apparent that the noise floor of the board with the mass damper and pocket of rocks near the arm socket has been reduced slightly, but this does not overcome the slightly pinched HF sound. Plastic derivative filler with mix in catalysts might be ok on budget plastic decks I used to attack with ‘plastic padding’ * back in the early 1980s. I used this to fill the voids in moulded plastic head shells and arm mounts, but resolution of those decks was low enough and the sound signature would have been that of plastic anyway. I leave the SQ of acrylics and substances like Corian to those who are expert in their application. I could still drill out the board from the underside to remove the rocks and replace them with lead shot. I suspect though that a better solution for the early Xerxes MDF Top board is either complete replacement with a better material. I can also envisage having the arm mount area reamed out to form a larger circular socket into which smaller round arm boards of a material of choice could be inserted as with later Xerxes 20 and TMS decks. * Plastic Padding is what we used for filling the rust holes in our old cars during the 1970s. American hot rod TV shows appear to refer to this material as ‘bondo’. We love those shows and the ‘can do.....will do’ attitudes! I guess that I aspire to be more a ‘Foose’ type man and strive to modify my record decks in the same spirit.........
3 A8 F753 F 9 C0 D 4 C26 A7 B4 000 DE941 B419 — Postimages Not quite a Foose, but here is my proposed ‘Rokler’, a deck made from a mix of Walker CJ55 plinth, DIY sub chassis and Roksan turntable running gear, fitted with my old Ittok LVII arm. Sadly this is not a runner yet as I need a bespoke stepped main bearing sleeve to mount the Roksan bearing. The Xerxes bearing is just mounted in a large rubber grommet to check the ride height. My usual go to engineering company are too busy with bulk contracts these days to help me with this part. On the plus side a friend has acquired a lathe for his workshop and has offered me free reign to use his facilities to make stuff. Time for some more fun!
Starting to work on repackaging my DAC in a new full size chassis. I've had the chassis for a couple years, but haven't got around to moving it before now, previously it was just in kind of a half chassis made from some aluminum panels. Mainly just drilling some holes for the RCA connectors and board mounts, cutting a rectangle for the power entry module, and wiring it back up in its new home. This is an old design, especially in the digital world, it was a late 90s project, my attempt at a very low jitter DAC, something where the transport didn't matter, and it was mostly a success. Really nice sounding unit, no electrolytic capacitors in the audio circuits or power supplies, all choke filtered, lithium referenced shunt voltage regulators, discrete transistor I/V conversion and single-ended output stage with no feedback, polypropylene and paper film capacitors, etc, etc. The key to the design is a highly isolated "dirty" input section that communicates across barrier isolators to the "clean" clock domain via an integrated sync pulse (around 1Hz) to stay in phase with the incoming clock derived from the S/PDIF. Anyway, no need to go into much detail on the inner workings, this is mainly about the packaging. I'll add some more pictures later showing the progress and finished job, the ones below just show the initial circuit board fit check in the new chassis ...
Well, the DIY part was really just intended to be about the steps to move the DAC into a new chassis, the rest was just some background info. The original design was kind of a production prototype, though I only built three units and didn't go beyond that stage, too much uncertainty. The one in the pictures doesn't have all the parts installed, and has quite a few little mods, it was a test bed, but it's still my main DAC (when working).
That’s was my immediate thought too. I’m always wowed by @Davey ’s technical prowess, but this is next level.
Quick afternoon project on my Khozmo passive preamp. I changed the series resistors from Amtrans AMRG to Audio Note Tantalum. I plan to let it run for a while before I do any serious listening, but I just needed to know what the where all about. I’m considering a silver wire upgrade on the signal path in there too.
I got a new integrated amplifier, a Denon from 1991. Of course the first thing to do is to model it's phono pre (with DC offset servo circuit) ... and then plan the mods before I even measure. It's got NJM2043DDs (like a Nakamichi). Crank up the gain and fix the loading. Make the MC button (which had strange frequency response) do something more useful. Ring the servo feedback with an inductor to fix what it does and doesn't do to the bass. Also, found a continuing investigation of phono loading noise, presented at a conference in 2018. Current noise of input devices matters due to cartridge inductance and its high resistance at high frequencies (not the spec manufacturers give, when the RCA inputs are shorted); the phono stage almost needs to be optimized for the particular cartridge (the 1500 ohms and 650mH shown is far above an Audio Technica at 400/410), deciding how to place the noise spectrum. --
Tonearm re-wire on a Pro-ject Xtension 10 turntable. I never liked the cheap tonearm wire and chap connectors included with my Pro-ject Evolution tonearm. So after accidentally bending a connector during a recent cartridge change, I decided to re-wire the whole tonearm with some quality third-party product. I never attempted anything like this previously, so I tried to do some research on the innerwebs, but directions of how-to are remarkably scant. Nevertheless, after buying a $16 solder kit on Amazon, I dove in. Everything went well, surprisingly, and now the table is singing again. The hardest part was the soldering, as the pins were microscopically close together.
My Current DIY Project: Building a modified version of an already modified Dynaco ST70 I have been planning this for awhile now, I just want to throw this out here and let some more eyes look at things. I hope I am not overlooking something before I order the PCB's. Amp and power supply schematic. The above PCB The regulated heater board schematic.
The PCB of the heater board. The Front Panel Express rear panel. and the front panel well...maybe not. FPE is fighting me on the front panel. Have to head to work. I will try again later.
Respect to anyone who's willing to have a go at tonearm wiring. Mad respect to the guy who jumps in and does it without previously owning a soldering iron!
Should the left and right be reversed from what it is here? When the amp is in position, do you want the left in/outs closest to the right speaker and vice versa? Maybe I'm crazy because everything's upside down here.
Hmmmmm. Good point. I hadn't even thought of that. Already fixed. See, these are the extra eyes catching things that I missed.
I am reposting the picture at the suggestion of a forum member here. He mentioned that they were small and hard to read if anyone actually wanted to dig into the schematics or PCB's. So here they are again.
