Mr.Sneis

The Koss is smoother and less bright than the 207 which in turn supposedly is supposed to be more neutral than the 407 model. The 207 tended towards brightness with better than 252s amps, I personally founnd the ESP950 to scale better than the 207 as well so slapping it on the 007tii should reap some real benefits. The koss is no slouch even next to the L700. Don't pay Darin Fong what he is asking for his stax adapter cable, it's just way too expensive for what he is asking. The extension cable was about $15 before the Massdrop run; I think these are hard to come by at present. The Amphenol plug is about $15-$20 via ebay sources or even Moon Audio. The solder work can be a little tricky and the fit and finish will be a little awkward due to the cable shape and connector form factor but it is what it is.

It's a long story this DAC but I can try to PM you later on with impressions.

Well it turns out I only needed to expand my skillset; touched up the chip by hand with a few passes of drag soldering technique and it is in business. Learned to not be too loosey goosey with the wick removal as well, bent some pins when I made a false move which could have been a quick job but more like an extra hour.

Hot air rework needed on a pmd200... Any advice for a guy who's just OK with a regular old iron? I'm local to a shop called circuit specialists that sells some lower end tools like this one for about $60: https://www.circuitspecialists.com/csi8786d_digital_hot_air_rework_station_with_soldering_iron.html Also frys locally has super chintzier looking stuff for $100: https://www.frys.com/product/6389401?site=sr:SEARCH:MAIN_RSLT_PG I do have a large supply of junk older gear to practice on as well thankfully.

Justin, any chance of interior shots?

That 3.0 schematic on their site but is awful resolution!

Been up with them for about a month. No progress made yet but when I spoke to their tech last he had said he needs to get the schematic from some guy in NL who may or may not have had it. He was pretty sure the problem lied in the digital board at least. Should probably try to hit them up again.

R2R is ultra popular again, manufacturers seem to be building them but vintage stuff also. Schiit and Metrum I think should be credited for a bit of this resurgence and making the cost somewhat affordable. I think Audio-GD is still big pimping pcm1704. USB is still crapshoot, it's gotten a lot better but the use of $$$$ expensive converters has gotten even more insane (like audio over ethernet). PS Audio really jumped the shark IMO with their super expensive Directstream DAC upgrade since the perfectwave days. Not too sure what happened to the cetoole analog upgrade board mods for older opamp based dacs, I think they disappeared or dried up. I've relegated myself to the vinyl realm and tried to look back but then got super screwed so I'm pretty much 98% out of the dac games now.

I'm not too familiar with how VMP works exactly but looks like I missed the train on the gorillaz album; I would join if I could but is it possible for you guys that are already members to buy a second ?

I'm done giving him the benefit of the doubt. I bought this DAC from Dreamwhisper and would not recommend anyone giving him any sort of trust in the future. He's been zero help and has been awful at any sort of reply. I love this hobby but stuff like this really just kills the enthusiasm. Will be going through the motions with PCX.

Without a doubt NoNoNoNoNoNo did this one. Why the heck is his name censored.

Yeah, trying to give him the benefit of the doubt so to speak trying to do what I can with what i have. Just sent a pm pleading to work out a return even though its across country and shipping is not insigificant. It's more likely the shoddy workmanship of NoNoNoNoNoNo that caused this than anything, very sad and stressful situation.

Unfortunately it didn't come to me for free! Purchased from a reasonably trustworthy member with a MO across countries, he hasn't truly gotten back to me either.

I purchased this DAC from another HC'er in Canada down to the states but it looks like maybe he didn't get around to testing it out before selling it to me as it locks onto digital signals but provides no useful output otherwise. I only have a glimpse of the history of this thing but it's lived a rough life. I am positive old forum favorite NoNoNoNoNoNo is the previous previous owner and the work here is very very bad. Lots of WTF and cold solder joints everywhere and bonus scorch marks on some box caps, that odd white wire is a jumper used after he lifted a pcb trace... As a novice I have since cleaned this thing up as far as I can get it, at least at my skill level, which includes removing all of the crazy bypasses and dexa regulators for 7805//7905 still no joy. Also looked to be a bit of soda or coffee spill near the power board and switches but it cleaned up OK and all regulators actually seem to test out fine. Have reached out to partsconnexion but no real schematic seems to exist. If anyone's willing to help me out with this thing or work on it for reasonable sum I would be greatly appreciative, otherwise I may have to suck it up and ship it to pcx. No magic smoke or obvious damage. The opamps are getting proper +/- 15v and a passive IV test seems to be no output as well. When locked on and powered up I can hear some intermittent static noises. And here it is currently all cleaned up.

https://www.audiogon.com/listings/amplifiers-stax-srm-252s-portable-amplifier-for-stax-009-2016-12-29-headphones-07853-long-valley-nj Hahaha, WHAT? Lots of wtf on quite a few levels.

Heard one of these at a meet on a few different setups, sonically didn't do anything that I liked. The owners however were smitten with them even with the harder to drive headphones, it seems these are really popular.

F*ck yeah! Well that was a lot easier than I thought. Something in my lead arrangement for the bypass cap that runs across the plate resistors must have been causing a short for the 18k resistor so the tube was only seeing 1k resistance on pin 1. What in the hell, 3 very long nights down the drain!!!!!

Thanks Doug. Speaking of. I just set the dmm on the plates for the right tube... looks like 105vdc and 88vdc Left tube looks normal 62vdc and 59vdc. What's my next step?

Waxing nostalgia? Wanted to get my feet wet into the amp years ago but never got around to it! I know I done f'd up.

Dear HC crew, I'm getting desperate and could really use some input on troubleshooting... First off I've been plugging away at this old thing for a while now, was always afraid to post up here for various reasons but at this point I don't have much to lose anymore. I do recognize I am still relatively new to DIY but I've been doing what I can with what I've got. I have a long winding thread with chronicle of the madness while it was working great; more than happy to remove the link if the admins do mind. There are links somewhere in there to the original schematic but it won't be of much help. http://www.superbestaudiofriends.org/index.php?threads/melos-sha-gold-2016-project-long-post.1745/ The TLDR without going into excruciating detail here's what I've done/changed on the amp, it has taken a lot of manhours on my behalf: Silicon Carbide Schottky Rectifier bridges to replace the HV and LV bridges Replaced all electrolytic caps and Sonicap film caps on the pre-amp out replacing the 6uf MKP's Sonicap for inputs and the bypasses Big honking 100uf 400v Solen PB to replace the "last" power supply electrolytic Left-Channel mod/reroute Remote locate TL783 regulator from pcb to chassis for heatsinking Swapped JRC NE5332N for a Signetics NE5332N Add a miller cap to darlington mosfets as seen on other Melos amps Rewired DPDT to Headphone mute Replaced Photentiometer with Tortuga LDR3x v 2.1 board Swapped out resistors on the tubes for the plates, heaters, grid stoppers and cathodes. Cut traces and relocated some resistors closer to tube pins Removed relays for warmup timer and Pre-mute when HP is plugged in I believe that about covers it, the amp worked GREAT with all of the above up until I got restless and then the latest round of futzing around and ended up with a big roadblock. Right now I can only get sound out of the left channel (both headphone and pre-out) and I've already sunk some heavy hours into troubleshooting! Here's what I wanted to do at first: Re-wiring for thicker gauge wiring for amp board inputs and outputs (16ga teflon to match the stock wiring) Re-glued final pre-amp caps with GC electronics silicone rather than hot glue Remove VU meter lamp wiring -22db passive attenuation resistor network on pre-out jacks Powered it up and boo, no right channel. My observed notes are as follows: No smoke, no smell Thought I might have over-heated a diac sharing the R headphone out pad, replaced with a new part L and R and no change Tried adding back in the VU wiring, no change Removed passive attenuation resistors no change Triple checked input output wiring no change Removed ground wire from amp to dpdt Mute switch; it seems to work the same with or without the ground wire Disconnected and re-soldered all transformer wiring Touched up/reflowed nearly every solder joint on the backside of the board HP jack checks out OK when just wiring Left channel directly to L and R poles, the DPDT switch seems OK too Tortuga volume board in passive configuration works OK, grounding to the board seems OK Amp board right hand MOSFET lights light up like clockwork Continuity of RCA input wires to rotary switch seems fine, especially considering the volume board in passive mode is OK Continuity of input and output wires on amp board seems fine, grounding seems fine Tubes light up like normal but I need to check the voltages. My next thought is to remove/refit the preamp film caps, maybe try running without them but I don't think they have any bearing on the headphone out. I'm tired and frustrated to have gotten too far invested to be taken out like this. Thank you for any help you guys can give!!

Arnaud, I just used 1/4 watt RN60 resistors like Birgir had originally shared. I don't recall if he states it in this way anywhere else but the stock resistors are glued onto the PCB and the leads are tightly spaced, I think I ended up desoldering the original resistors with a pump or braid and then snipped the resistors off the board with a flush cutter. After that is a piece of cake.

VMP is using the same plates from the Mofi release and pressing at RTI. I have the damn MFSL release already but tempted just to sign up to triple dip. It's pretty sickening actually now that I am typing it.

The for sale listing you got those from clearly had the driver crooked to begin with. Stax used black double sided adhesive for both the driver and earpads. Over time it weakens and gets really nasty to deal with, and yes it seems to me to be very common, When you separate the baffle from the housing you've got to do so carefully as stated above, it is simply too easy to puncture the driver dust covers. Doing this will also probably destroy the outer facing open cell foam. Cleaning all the old adhesive off is time consuming and nasty. Buy some polyeurethane glue, probably best to order online as hardware store guys are clueless.

But everyone at HF thinks it's SUCH a great amp, 009 + 007t ooh lala. (tons of sarcasm implied!!!)

I don't mean to make this post as a slam on the 007a but once upon a time I heard a brand new pair pretty much straight out of the box and it was one of the worst Stax experiences that I have ever had, terrible fitment (I suspect this was the major problem?) and something about the bass was a mess. That said, I would totally give them another try if I could but at the same time I have had maybe 3 pairs of o2mk1 in my life and never an issue.