Time to DIY like it's 2009! (hobby has changed, man)

Discussion in 'DIY' started by Beefy, May 29, 2021.

  1. Philimon

    Philimon Friend

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    @purr1n Strong with the force this one.
     
  2. insidious meme

    insidious meme Ambivalent Kumquat

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  3. Beefy

    Beefy Friend

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    The next project I have been working on is my AMB γ2 DAC. There is a great SBAF thread on this DAC from just a few months ago, with excellent measurements and listening impressions, that I would encourage everyone to read.

    From a DIY/historic perspective, the preceding AMB γ1 DAC was released in 2008, and it was the first mainstream DIY DAC that I became aware of. Everything about the project was brilliant. Ti Kan’s amazing documentation and instructions made it eminently achievable for idiots like me. The board sandwich was incredibly compact, cramming USB, coax, and optical inputs into a credit-card sized box. The lovely little multicolor selector switch gave great functionality and pre-made panels made it look professional. But above all, it offered incredible sound quality for the price and size.

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    Ti released the γ2 in 2009. It used the all the digital side from the γ1 but added an entirely new DAC stage built around the Wolfson WM8741, and it even had an optional 24/192 ASRC. In terms of sound, it never quite hit the detail and punch of my big ESS9008 DAC, but for the size and price, the γ2 was amazing. I designed my own minimalist panels, and I still think it looks stunning. My γ1/2 has seen almost daily usage for over 12 years, serving as the DAC at my office desk. It fed my M3 and Millett Hybrid headphone amps for many years, then some Audioengine A5+ speakers for many more. A true workhorse.

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    Unfortunately, the γ2 is starting to show its age. I replaced all the electrolytic capacitors with new Elna Silmic II because why not. But real issue is that the PCM2707 USB interface is simply obsolete. When all my listening was my own FLACs using foobar and ASIO4ALL it was fine, but with a much heavier dose of Spotify and other sources I get random hitches in the audio stream. My new laptop docking station also dumps a HEAP of digital noise into the USB line, which is audible at high volumes. I tried a whole heap of things to fix this, but a synchronous UAC1 interface and USB power just does not cut it anymore.

    This took me down the rabbit hole of modern transports, and a big decision needed to be made about how I wanted to ‘serve’ my digital music across all my different rigs. Ultimately, I decided against something like the Pi2AES and Roon despite the obvious benefits; my headphone rigs are right next to my home and work PCs, and network access at work is problematic. So I decided to go with a modern USB transport to just use my PC as source, and settled on the JLSounds I2SoverUSB. This is a well implemented XMOS XU208 USB interface that comes with galvanic isolation, low-noise isolated power supplies, and re-clocking all on one board. I am drawing SPDIF from the board to feed the JLSounds coax/TOSLINK output board and powering the USB-SPDIF box and the γ2 with a couple of cheap-but-good switching wallwarts. To make this at least somewhat resemble DIY, I designed and 3D printed a case using some spare nylon filament I had lying around. Nylon is far from the prettiest 3D printing material, and it is nigh on impossible to post-process, but it is tough. You could drive a car over this thing and it would be fine.

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    So where does this DAC sit against the competition? Well, the whole setup works perfectly, I now have flawless digital music coming from my γ2, with zero audible background noise, and it will live to fight another day. But there is no way I would build another γ2 today because it has surely been surpassed in price/performance by commercial gear. Using Schiit as a metric, you could buy a Modi for the price of the I2SoverUSB board alone. For the price of the whole γ2 setup, you would be more than half-way towards a Bifrost. The value is just not here like it was in 2009. I do intend to keep this for now, but I am well down the path of building a replacement DAC to upgrade my office listening rig. The γ2 will probably get demoted to become the DAC for my TV, where it will be a huge improvement and continue to be loved for many more years.
     
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  4. atomicbob

    atomicbob dScope Yoda

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  5. Cspirou

    Cspirou They call me Sparky

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    What are the DIY DAC options out there? Last I checked it was really thin and all that was available were modules or eval boards. Beezar has some boards including some USB jitter/noise blaster but otherwise can't find too many.
     
  6. Hrodulf

    Hrodulf Prohibited from acting as an MOT until year 2050

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    I wouldn't DIY a dac today. There's TPA, ACKO, Beezar and bunch of Chinese stuff. Lately much advancement has been made into filtering and that's largely out of reach for DIY.
     
  7. Beefy

    Beefy Friend

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    Yes, it's not easy. DIY DACs, in terms of buying a board you can solder your own DAC chip onto and have a competitive end result are definitely thin on the ground. Obviously the AMB γ3 is an option after the γ2, but I didn't really want to go that way.

    So that does just leave you with modules, which reaaaaaaaly stretches the bounds of what you can call DI*Y*. And then, same problem as all the other DIY gear, where's the value proposition versus commercial gear? But there are a couple of gems out there.

    Spoiler alert, I'm planning a build with a Soekris module. If I can ever get someone to answer my emails about buying the f@#$ing boards.
     
  8. Hrodulf

    Hrodulf Prohibited from acting as an MOT until year 2050

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    Check DIYAudio forums. They pop up from time to time for good prices. Just make sure you get the latest revision. Not sure when output pop protection was implemented. The early stuff was pretty brutal.
     
  9. Beefy

    Beefy Friend

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    Yeah, there was a new revision announced in late April with some nice improvements to the power supplies and the R-2R ladder itself. Definitely gunning for this one. It was supposed to be ready to ship through official channels, but not yet.
     
  10. JeffYoung

    JeffYoung Friend

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    I still plan on building a DIY DAC at some point, but I have yet to finish all my amplifier projects.

    If you want a nice headphone amp / preamp, my Pass HPA-1 clone is a fun build....
     
  11. Beefy

    Beefy Friend

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    Found the thread. Your metal work and board design skills are epic!

    To be honest, even if the the HPA-1 is significantly better, it still seems a bit redundant considering my M3. And if I was going to build something bigger, more powerful, discrete with MOSFETs, I think I would be more inclined to go balls deep and build a fully loaded B22.

    In a similar vein, I did find the Whammy on diyaudio, which is the smaller sibling of the HPA-1 in full DIY form, with OPAMPs instead of discrete voltage gain. It looked like a really neat little project that showed a lot of promise as a modernised M3. But rather than focus on achieving the best possible performance from the design, the diyaudio thread sort of devolved into how cheaply people could make it. Finding whichever <$1 BJT OPAMP would work without audibly oscillating, and celebrating when DC offset was under 20 mV (atrocious considering the design has DC blocking caps on the input). I'm sure it can still be a great little amp, but it really sapped my enthusiasm.
     
  12. Beefy

    Beefy Friend

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    Next up is my Cavalli Exstata electrostatic amp. The website is no longer functional, but it is archived in the wayback machine. There are also extensive development and build threads on Head-Fi. I have mixed feelings about this project. The design goal was to build a relatively good, relatively cheap electrostatic amp with widely available in-production parts. Basically, it was meant to be for people who could not or did not want to build one of Kevin Gilmore’s designs using hard-to-find JFETs. There were gushing reports of amazing sound quality from respected community members, and the outward view was that the design was being heavily vetted and refined. I was an extremely enthusiastic participant, and I completed one of the first ‘production’ solid-state builds.

    I could not describe the design very well 10 years ago, let alone now! But I do know that the power supply is a CCS-fed shunt regulator at ±300V. The solid-state design has a differential JFET input cascoded with high-voltage BJTs (removes need for a low voltage power supply for the input stage), and the output stage is a Wilson current mirror. Gain is nominally 1000x, but I only measure about 500x in my amp, which might come from a combination of low JFET transconductance and a shitty multimeter that does not measure AC properly. My amp was finished with a dual/balanced PGA2320 volume control and machined Teflon Stax Jacks both courtesy of luvdunhill. It also had a custom magnetically shielded SumR transformer, AMB E24 relay driver, HiFi2000 Pesante case and FPE panels. I can summon no humility, I still think this thing looks f!@#ing gorgeous.

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    But there are some problems here that need addressing, because in some respects the design goals were met, and in others the project did miss the mark. There were reports of measurements that put distortion at 1% THD into 100V P-P, which is not great for a solid-state design meant to output 900V P-P, although I never saw the measurements myself. The amp was prone to oscillation that was only partly fixed by grounding the heatsinks. The power supply liked to self-immolate; if something happened to the load the entire CCS output would go through the shunts without any mitigation/protection, and insufficient heatsinking meant the shunt BJTs would pop in under a minute. My power supply and several others would physically buzz during cold starts, an issue that was never properly identified. The ‘in-production’ benefit ended up being highly questionable because you needed heaps of the JFETs to get a matched quad, costing considerably more than if you just bought a set of 2SJ74.

    It all became a bit melodramatic. There were unfounded accusations of copied design elements, and it seems some feedback on circuit performance and safety was not incorporated. People who previously loved the amp distanced themselves, there were obvious shills trying to drum up interest to sell their DIY builds for profit, and at at least one novice builder offloaded a poorly built amp on an unsuspecting rube. There were talks of a V2, but the design never went further, Cavalli moved to his commercial ventures, and all the DIY pages are no longer there.

    This is where I really started to lose my tolerance for the hobby drama, which made it hard to love the amp. I wince every time I turn it on, because this might be the time that the buzz finally kills the power supply. Or perhaps an amp board might finally oscillate itself to failure, causing the PSU to commit sympathetic seppuku. In my mind it is a ticking timebomb that I cannot in good conscience sell.

    You want to know the most annoying part? When combined with a pair of Stax SR-Lambda normal bias (fully restored by me in 2010 with NOS drivers, new cable, and new pads) the amp does sound gorgeous, almost certainly my best sounding rig for any music where the comfortable warmth of the Crack/HD650 is not appropriate. This makes it hard to hate the amp. A huge part of this is due to the SR-Lambda being incredibly easy to drive, and my normal listening being at about 20 VRMS where distortion (real or imaginary) is not a problem. But in terms of revisiting this gear? This is probably a dead end for me. If the Lambdas die, I'm not sure that the amp could drive modern Stax well. If the amp dies, I will not pay electrostatic amp money just for the Lambdas. With huge advances in dynamic and orthodynamic headphones, I cannot see how the cost and limitations of electrostatics make sense.

    All that said, I am a stubborn SOB, so I am going to string this gorgeous beast along for as long as possible. The amp has always run hot, using every single mW offered by the 30 VA transformer. So I moved the amp onto a perforated steel insert, and switched out the partly-perforated covers for fully-perforated covers. With better airflow it runs quite a bit cooler now, which will hopefully increase longevity. I also reckon the perforations make it look even better; leaner and meaner. But ultimately, if and when this amp dies, it dies, and that's that.

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    Last edited: Jun 4, 2021
  13. gepardcv

    gepardcv Almost "Made"

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    I arrived on the DIY electrostatic scene after the Exstata, so haven’t run into one. Is there at least a 5M ballast resistor on the output bias line from the power supply? There is evidence that Cavalli didn’t put that (absolutely critical) safety measure on at least one unit of the Liquid Lightning.
     
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  14. JeffYoung

    JeffYoung Friend

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    I have a first-generation Vanquish. The thing is cantankerous as hell with appalling reliability. But boy does it look great.

    When I get tired of fixing it I'm just going to drain all the fluids and park it in my front hall.

    At least you won't have to drain the fluids. ;)
     
  15. Beefy

    Beefy Friend

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    Yep, R19 and R22 on the PSU schematic are 4M7 resistors for the pro and normal bias respectively.

    HA! That is such a great comparison. We have these 'things' in our life that we love despite their faults, and hate despite their merit. It would be so much easier if we weren't human.
     
  16. dBel84

    dBel84 Friend

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    Tread carefully, I am open minded but baseless claims are just that.. dB
     
  17. Beefy

    Beefy Friend

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    I'm just reporting what happened as I saw it. But if I've got anything wrong, please let me know. I'm still inside the edit window, and will gladly fix anything that is incorrect.

    I want the melodrama from 11 years ago to stay there. This whole thread for me is about moving forward.
     
  18. Fallenangel

    Fallenangel Friend

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    Holy shit guys! I just had to install a TTS app to read everything. This is awesome balls!

    Hi @TomB, hope you remember me. I already said hi to the others, I hope.

    This is beyond awesome to read.

    I honestly might just get my soldering station out of storage because of this thread.
     
  19. Beefy

    Beefy Friend

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    Well, that would make my day.

    I'm still not sure whether DIY like we remember makes sense, but you can still get a lot of mileage out of nostalgia!
     
  20. dBel84

    dBel84 Friend

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    I think there is still hope. A lot of DIY was experimentation - an attempt to see what worked and what didn't. Perhaps a museum to failed projects would be "fun" - some failed because they were unstable, these could be rethought, some because they were not any better than other circuits and some sounded great and were inspirational (I thought) but never gained any traction. One of the reasons that I have been slowly working through the First Watt inventory is to try different things to see how they sound. The M2 is a great example. I loved Doug's transformer coupled mosfet amp ( don't recall what it was ) but had passed on a steal to pick up an M2 before I heard it. The idea of using a cheap transformer ( not Doug's the M2) as a VAS just didn't make sense but now that I have head it, it might well be the FW amp that I return to most often and has spent the most time in the system.

    anyway , getting distracted and railing off topic as always but I would love to see the DIY "bug" thrive in our community again.

    ..dB
     

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