The 22mH is for Kubelik. I believe the part number you want is RL181S-123J for 12mH. @commstech may have compared the two types on his Kubelik though i dont have a link.
Vunce, yes please use the included L. I have tested the bourn part and it gives a different effect, probably due to a different dcr. The L in the kit is definitely a better one after some comparison.
Wow, this is great news. I just received a parcel today - a Dorati kit and set of monoAmps.
Calling in "sick" for the next week or two I guess.
Your Dorati looks great Ross!
I’ve had mine playing for past few days. A clone Salas Ultrabib shunt psu is setup to deliver 250mA@14vdc to feed power to Dorati. Initially, my TP4/7 readings were low. After consulting with Abrax he calculated the values for each channel SOT resistor. Installed these resistors and TP4/7 are bang on perfect! (4.90v/4.92v)
Dorati was built in stock form just to get started and confirm all works as it should. I was very pleased with what I was hearing, but after two days I felt the need to play with the output capacitors. I didn’t want to get crazy with offboard cap banks and added wiring so my experimenting was limited to what I could reasonably fit onboard. I ended up with BlackGate std 220uF, 16v elco’s with smd CDE FCA film bypass caps soldered between the legs underneath the board. Dorati now sounds wonderful!! And it’s dead silent between music tracks, no hiss or noise of any kind. I was concerned with the lower value cap negatively effecting the low frequency response, but that is not the case, all is still good. This is my first experience with a TDA1387 dac and it has a slightly different sound compared to my NOS R2R dacs. This is a nice change though and Dorati is definitely a keeper. If this is just a “starter” dac, I am intrigued by how the sound would improve going up the conductor name ladder.
Btw, Richard and his wife do a fantastic job packing these kits and their support is top notch! Well done Team Abraxalito
https://www.cde.com/resources/catalogs/FCA.pdf
I’ve had mine playing for past few days. A clone Salas Ultrabib shunt psu is setup to deliver 250mA@14vdc to feed power to Dorati. Initially, my TP4/7 readings were low. After consulting with Abrax he calculated the values for each channel SOT resistor. Installed these resistors and TP4/7 are bang on perfect! (4.90v/4.92v)
Dorati was built in stock form just to get started and confirm all works as it should. I was very pleased with what I was hearing, but after two days I felt the need to play with the output capacitors. I didn’t want to get crazy with offboard cap banks and added wiring so my experimenting was limited to what I could reasonably fit onboard. I ended up with BlackGate std 220uF, 16v elco’s with smd CDE FCA film bypass caps soldered between the legs underneath the board. Dorati now sounds wonderful!! And it’s dead silent between music tracks, no hiss or noise of any kind. I was concerned with the lower value cap negatively effecting the low frequency response, but that is not the case, all is still good. This is my first experience with a TDA1387 dac and it has a slightly different sound compared to my NOS R2R dacs. This is a nice change though and Dorati is definitely a keeper. If this is just a “starter” dac, I am intrigued by how the sound would improve going up the conductor name ladder
.Btw, Richard and his wife do a fantastic job packing these kits and their support is top notch! Well done Team Abraxalito
https://www.cde.com/resources/catalogs/FCA.pdf
Attachments
The best I can describe the difference I hear with Dorati is the music sounds closer (distance-wise) to me. (and I'm splitting hairs here)
Dorati is quite an excellent performer, especially when you factor in how wallet friendly it is. I'd say the easiest way to take Dorati up a notch is tweak the output caps.
Nice work Richard!
Dorati is quite an excellent performer, especially when you factor in how wallet friendly it is. I'd say the easiest way to take Dorati up a notch is tweak the output caps.
Nice work Richard!
Thanks again Vunce - the aim was to get satisfying sound but without the hit to the wallet, so I'm glad that goal has been reached at least for you.
As regards your interest in how the sound changes on 'climbing the conductor ladder' I see the primary weakness of Dorati is the fact that its LC filter isn't very steep. The filter's been kept simple so that it can be available as a kit - a more complex filter needs pre-selected capacitor values. The difference a steeper filter makes isn't always apparent, it rather depends on the kind of music. I notice the filter effect most on solo piano, especially close-miked piano which has stronger dynamic contrasts.
As regards your interest in how the sound changes on 'climbing the conductor ladder' I see the primary weakness of Dorati is the fact that its LC filter isn't very steep. The filter's been kept simple so that it can be available as a kit - a more complex filter needs pre-selected capacitor values. The difference a steeper filter makes isn't always apparent, it rather depends on the kind of music. I notice the filter effect most on solo piano, especially close-miked piano which has stronger dynamic contrasts.
Thanks for the interesting (as ever...) feedback, Vunce!
Nice to read this little DAC responds well to conventional cap tuning.
Hmm... as posted, I have quite a few cap tweaks in mind... I need to get my house ready and then get one of these kits
Inspiring... thanks again to both of you!
Claude
Nice to read this little DAC responds well to conventional cap tuning.
Hmm... as posted, I have quite a few cap tweaks in mind... I need to get my house ready and then get one of these kits
Inspiring... thanks again to both of you!
Claude
Had a quick look at the Dorati schematic
I guess there must be special reasons for the very high original 1000uF output cap. Perhaps to drive low impedance HP directly, perhaps designer's choice... There must also be a reason for the 27k resistor at the output (to ground, saving a short cut or too low output impedance?). Or am I missing something?
Whatever, my understanding is the following...
Should you want to keep the resistor but only to drive a preamp or an amp directly, then it is very likely the device you will drive won't have an input impedance lower than 10k. With the 27k in parallel, that gives us a 7.3k load. That is already a worst case...
Based on this load, a 5uF cap would be more than enough to enable less than 5Hz cut off frequency, which is enough to pass safely any 20Hz without any reasonable loss. In short, any 4 to 5 uF cap could do the trick in that case. There must be quality ones at affordable prices with small footprints...
Now, should you get away with the 27k resistor, something I can't recommend unless you know what you are doing, and have say an already lowish 20k "next device input impedance", driven through reasonable connecting wires, then you are likely to get away with a 1,5uF cap... preferably though one suited for audio with low ESR at low frequencies etc, well the ususal bits
Just thinking out loud, well noting that Vunce's solution is flexible and probably already 90% of what is sonicaly achievable on a device that is perhaps not meant to be used with real 20Hz closed LS
Claude
I guess there must be special reasons for the very high original 1000uF output cap. Perhaps to drive low impedance HP directly, perhaps designer's choice... There must also be a reason for the 27k resistor at the output (to ground, saving a short cut or too low output impedance?). Or am I missing something?
Whatever, my understanding is the following...
Should you want to keep the resistor but only to drive a preamp or an amp directly, then it is very likely the device you will drive won't have an input impedance lower than 10k. With the 27k in parallel, that gives us a 7.3k load. That is already a worst case...
Based on this load, a 5uF cap would be more than enough to enable less than 5Hz cut off frequency, which is enough to pass safely any 20Hz without any reasonable loss. In short, any 4 to 5 uF cap could do the trick in that case. There must be quality ones at affordable prices with small footprints...
Now, should you get away with the 27k resistor, something I can't recommend unless you know what you are doing, and have say an already lowish 20k "next device input impedance", driven through reasonable connecting wires, then you are likely to get away with a 1,5uF cap... preferably though one suited for audio with low ESR at low frequencies etc, well the ususal bits
Just thinking out loud, well noting that Vunce's solution is flexible and probably already 90% of what is sonicaly achievable on a device that is perhaps not meant to be used with real 20Hz closed LS
Claude
Great stuff Vunce and thanks for the feedback. I will start soldering soon, I hope.
I'm wondering why/what was the motivation to change the output caps from polarized 1000uF caps to non-polarized 220uF caps? And you are very happy with the results. What preamp are you using or are you also feeding a power amp directly from the Dorati?
Hi Jim,
Good eye! Yes, I replaced the silicon diodes with LT4320 active rectifiers. Very small size because they use a pair of dual mosfets and both sides of pcb are populated. JPS64 designed them to use with a revised Yarra preamp regulated psu. Dorati is the perfect "set it and forget it" component, the size, layout and components don't lend themselves to much tweaking. Enjoy it how Richard designed it, it really sounds great. MiroDac is a living entity that can be configured from "mild to wild", so it has potentially a higher level of performance.
Hey TC,
The BG caps installed are polarized. My motivation was driven by past experience with output caps in various gear. If significant capacitance is required I try to use the smallest size electrolytic cap without reducing low frequency response. This topic is a hotbed of differing opinions, but I fall on the side that different caps can make a difference in sound. My current audio chain is: Dorati-->SCG Preamp-->Big Mofo Class A amp =
https://www.diyaudio.com/community/threads/schade-common-gate-scg-preamp.380487/page-15
Yes that's the main reason. A secondary reason is I'm usually driving a trafo from my DACs and they tend to need a larger coupling cap to keep the LF resonance well damped.
The resistor is an attempt to pre-charge the caps so there's not such a huge thump on plugging in any headphones.
hello jimk04, I think the Miro 1862 are built with an experimenter spirit in mind. Like what miro said, he excluded psu on the board, with a few options eg. using separate supplies for the different stages, onboard glue logic or external and went to a textbook Opamp output stage. There were a few suggestions for output stages but Miro's aim is for the builders to embark on their own adventures, saying that the output stages do make more discernible differences that than the types of psu boards used (psu1 and 2). It has been interesting to see many who went the passive Iv to tubes, different op amp, discrete devices...
Abraxalito offers a complete design, tuned and voiced by ears of himself and wife. Like Vunce mentioned, of course Miro can be tweaked and the potential of a higher performance possibility is in the hands of the builders due to its flexibility. By default, using the textbook OPA627iv on the Miro 1862, i find myself more inclined to connect to Abraxalito's dac whenever i have the 'which one today?' question on my mind. I will spend some more time when i can on the output stages on the miro dac, and i do agree with Vunce, who has experimented with it long enough to realize its potential that it can be built to a good level. Abraxalito has provided a good sounding product at an incredible price that perform beyond my expectation that i will need to really explore what i can do on the miro ad1862. I have to admit i have to really work harder on this.