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Gieseler Audio

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  1. Hi guys, I was thinking about developing a in house XMOS-based asynchronous USB to I2S interface. EBay is full of them so I’m obviously not trying to compete in that area but it would be good to have my own version to use in GIESELER products. We could probably do a stand alone version as well which may be of interest for DIY projects. Rather than just a basic unit I was thinking of including full galvanic isolation plus re-clocking on the I2S outputs. Say similar to the Singxer F1 but without the S/PDIF output. The XMOS chip UX208 that most manufacturers are using is the XU208-256-TQ64. It cost the huge sum of $16 & is available from DigiKey. https://www.digikey.com.au/product-detail/en/xmos/XUF208-256-TQ64-C10/880-1112-ND/5358025 XMOS supply development firmware. I have a good coder so he will handel that side of things. The main issue will be the Windows USB driver. Thesycon have a free evaluation driver (with the beep) so I need to investigate a production version. I have done a few four layer boards laterly, have a new reflow oven & my C++ coder is confidant - how hard can it be? Well what do you think or am I dreaming!
  2. Multichannel DAC

    Hey guys it takes me forever to build two channel DAC's - Eight channels would be a deal breaker for sure. I do like the buying beers part though!
  3. DAC as a Pre Amplifier.

    I think Trevor is spot on - some how the un- selected input is loading or shorting things out. Ditch the Y-cable adaptor & just use a standard lead & then try each input separately.
  4. GIESELER Groß DAC official release

    It certainly looks like a interesting device. I will do some investigation.
  5. DAC as a Pre Amplifier.

    The power supply can have a big effect on sound quality so with the Gross DAC I went overboard in that area. There are twenty independent regulated internal supplies. Just for supplying the DAC chip alone I use four 800ma ultra low noise regulators. Also diode & capacitors choice will influence the sound so I’m using special parts in that area as well.
  6. DAC as a Pre Amplifier.

    Hi Guys, I think Stereophilus summed it up petty well in that a DAC is not ideal to drive multiple inputs. When you parallel up inputs your impedance will keep going down making it harder to drive. Some DAC’s have a beefy line output stage & will drive lower loads with out a problem but that is not the norm in DAC output stages.
  7. Klein DAC II owners thread

    The sample rate is only displayed if using the USB input. The Amanero USB board outputs this info which I use to control the display. To add the S/PDIF sample rate info would need quite a bit more complexity in the design so I gave that a miss.
  8. GIESELER Groß DAC official release

    I am still planning on sending one to Melbourne for demo purposes but I need to fill the current orders first. It would certainly be good to see how it compares to the Mola Mola Makua. Ouput transformers; Actually there were several reasons but the first was sound quality. Ages ago and just on a gut feeling I ordered a pair of entry level Jensen’s line out transformers from Parts Express. I jerry rigged these up to a Klein II DAC & the result was a serious step up in sound quality. This was a big surprise as the Klein II has an excellent class A output stage & I really wasn’t expecting an improvement but there certainly was. Then after some research I discovered that the PS Audio Direct Stream & Linn Klimax both used line output transformers for the audio out. Now these are seriously good sounding units so that certainly helped confirm that line output transformers was a good way to go. Also the Direct Stream was actually using Jensen transformers. I also wanted to a try a direct out approach from the DAC chip and a transformer is an ideal way to do this. There were some hurdles on the way though as the transformer needs to be well matched to the DAC output & you also need a reasonable drive level. Fortunately the AK4497EQ chip has some special heavy load mode options that can be implemented from the registry. Anyway to cut a long story short I had some helpful suggestions from a AKM engineer & by experimenting with a range of Jensen transformers finally got a great result. I did need to move up to the top PC mount transformer to get two volts RMS out though & this bumped the cost up a bit. The other bonus is by using a transformer output stage I can offer balanced or standard RCA out as well as full galvanic isolation if required. Phew! A need another coffee after that explanation!
  9. GIESELER KONVERTER (DAC/Preamp) Official release.

    Hi Guys, small update. We have put a massive amount of time into the Groß DAC firmware & as a result some of the new features will be able to be incorporated into the Konverter. Things like “heavy load mode” , DSD filter roll off & sound quality select mode. Some off these features will be switchable in the menu & others are behind the screen stuff. Bottom line is they all add small improvements to the sound quality so I definately what to incorporate them into the Konverter. As soon as the work load backs off a bit I will get on to it. The firmware upgrade is dead simple. Just a matter of replacing a plug in chip. Stay tuned.
  10. GIESELER Groß DAC official release

    Hi Guys, well I’m steadily building these but it is still a slow process with me doing all the work. I lost a little time tweaking the firmware a bit but it was well worthwhile. The menu structure has been improved a bit & also the clicks/pops with mixed DSD/PCM playback now removed. I will thoroughly test it over the weekend & if bug free will send out upgraded chips to current owners. The firmware upgrade is dead simple - just a matter of replacing the plug in chip with the new one. I’m also trying to source better custom packaging. The demo unit for Victoria is still on but I have to complete current orders first - now twelve - four finished & eight to go. As they say - no rest for the wicked!
  11. Groß DAC owner's thread.

    The official release thread is quite long so I thought it best to start a separate one where owners can leave feedback.
  12. MQA on non-MQA DAC

    OK just tried a couple of tracks & in both cases the DAC displays the same sample rate indicated in the app. eg with Norah Jones 96k I don’t have a bit rate info on my DAC so can’t check that.
  13. MQA on non-MQA DAC

    No - I think the only DAC’s that will indicate any MQA info will need to be MQA certified. On the Auralic Aries when playing all Master tracks the App (Lightning DS) displays bit rate/sample rate & that it is MQA.
  14. MQA on non-MQA DAC

    Actually that is very interesting because I just happened to check out Tidal Masters tonight while testing a different DAC & noticed quite a bit of new content. Being a Norah Jones fan I immediately fired up the “come away with me “ album” & also the new Jack Johnson album. Both were MQA & sounded exceptional good. I’m using a Auralic Aires which although not MQA licenced may have some sort of unofficial MQA decoding. I tried some more MQA/Masters stuff & it all sounded very good to the end result where I was told to please “turn it down” by the rest of the house hold.
  15. GIESELER Groß DAC official release

    Hi Joe, no I have not forgotten about the demo unit for you guys. The slight hold up is I have now sold ten so quite a lot of work ahead of me. I have brought Snoopy8’s home for a quick listen in my system. OMG it really does sound amazing. I haven’t herd the Groß DAC in my system for a few weeks & had forgotten how good it sounds. At work I compared the USB only version to the three input version & did not notice much difference but on my home system the USB only is a little better. Hi Cameron - glad you approve - yours should not be too far away.