I recieved my kit very quickly - just a couple of days, and it is a very easy kit to assemble.
Everything is very high quality and the kit can be assembled in a couple of hours if you have some solder experience, and installed in half an hour on a PC. One tiny remark though: Unisolated not so high quality output bushings - only usefull for non conducting cabs.
I have tested the DDDAC with 3 output options, and Doede does not want us to discuss ´not qualified´ transformers in this thread, so we could move that to new threat if someone is interested.
But I suppose that a short evaluation will be ok. I tested it with my Sowther 3603z low impedance trafos - a lot of detail, lots of bass, but a little aggressive mid/highs. After having read TriodeDicks evaluation I guess it is because i didn´t load it with anything else as the preamp on the output, which gives a lift in the upper end. Next test was the intended capasitor coupling, also without other loading than the preamp (The DDDAC looks directly into a 50K pot). Lots of details and bass like the trafo, and also a little agressive in my system. Last I tried the Sowther 3575z that TriodeDick didn´t manage to get delivered in time for testing. They sound very good, with a subjectively tiny loss of detail, and some loss of bass with a 10K load. I havn´t used the RF caps yet, but intend to try 5 nF. I may also try some Pass designed active IV solutions later.
One question: A user earlier asked if he could use a slightly higher resistance than the 133 ohms, and you answered ´not more than + 10%´. I have seen a Portoguese testing the 1794A very detailed in another thread. He found that the optimal loading seemed to be 50 ohms pos. to neg. That gives a much lower output and a lower THD, but would that be true for your design also ?
Best regards
Arthur.
Everything is very high quality and the kit can be assembled in a couple of hours if you have some solder experience, and installed in half an hour on a PC. One tiny remark though: Unisolated not so high quality output bushings - only usefull for non conducting cabs.
I have tested the DDDAC with 3 output options, and Doede does not want us to discuss ´not qualified´ transformers in this thread, so we could move that to new threat if someone is interested.
But I suppose that a short evaluation will be ok. I tested it with my Sowther 3603z low impedance trafos - a lot of detail, lots of bass, but a little aggressive mid/highs. After having read TriodeDicks evaluation I guess it is because i didn´t load it with anything else as the preamp on the output, which gives a lift in the upper end. Next test was the intended capasitor coupling, also without other loading than the preamp (The DDDAC looks directly into a 50K pot). Lots of details and bass like the trafo, and also a little agressive in my system. Last I tried the Sowther 3575z that TriodeDick didn´t manage to get delivered in time for testing. They sound very good, with a subjectively tiny loss of detail, and some loss of bass with a 10K load. I havn´t used the RF caps yet, but intend to try 5 nF. I may also try some Pass designed active IV solutions later.
One question: A user earlier asked if he could use a slightly higher resistance than the 133 ohms, and you answered ´not more than + 10%´. I have seen a Portoguese testing the 1794A very detailed in another thread. He found that the optimal loading seemed to be 50 ohms pos. to neg. That gives a much lower output and a lower THD, but would that be true for your design also ?
Best regards
Arthur.
I'm not Doede, but my 2p....
Have no fear about using lower value I/V resistors. Heed the advice about not going much higher than 133R per phase, but no issues going lower. I use 16R2 I/V resistors with a single deck and an active (Broskie Unbalancer) output stage. Lower value I/V will reduce distortion. but you'll probably be adding back whatever you gain there by distortion produced by the active output stage, unless using op-amps with massive quantities of feedback.
I don't think Doede was trying to totally quash any discussion about transformers, just not in this thread, please. (He does offer a transformer output option so 3'rd party options are probably best discussed in another thread rather than in his "official" thread, anyway, out of courtesy.) I think Doede was a little frustrated about misinformation on transformers and the "blind leading the blind"..... eg. measuring the resistance of transformer primaries, resulting in them becoming magnetised.... That sort of thing. Someone should start another thread, where people can discuss their experiences and the virtue of 600R:600R vs 10k:10k, cheap (relatively speaking) Cinemag, vs expensive (relatively speaking) Lundahl or Doede's Sowter option.
I have completed a lot of work on the power supplies and the cabinet, but I missed an important point: the DDDAC has both an I2S and USB inputs, but if does not have a classical SPDIF (44.1/16bits) RCA input.
I have been told that there are SPDIF To I2S conversion cards available for sale on the dddac Web site , but I have not found it.
How can I do To connect a CD drive to the dddac?
Thanks
I have been told that there are SPDIF To I2S conversion cards available for sale on the dddac Web site , but I have not found it.
How can I do To connect a CD drive to the dddac?
Thanks
Beardman thank you,
the system has been running all day, and I am very satiesfied with the sound, so no more changes right now
And a Happy Holiday to all of you.
Best regards
Arthur.
the system has been running all day, and I am very satiesfied with the sound, so no more changes right now
And a Happy Holiday to all of you.
Best regards
Arthur.
It seems that there are no SP/DIF boards on Doedes site anymore, and I really hope that I am correct, but I read somewhere that Doede had recommended the TP SP/DIF solutions, and they are here:
The S/PDIF Transceiver Module
S/PDIF 4:1 Receiver/MUX Module
I have used both, and they work fine.
The S/PDIF Transceiver Module
S/PDIF 4:1 Receiver/MUX Module
I have used both, and they work fine.
on spdif, all correct! thanks guys for jumping in
on the Rload, well my design goal was to get max output at low distortion, hence I use 8 Volts supply voltage and 6k Bias resistor, where ALL other 1794 designs use 5 Volt and datasheet 10k...
I get 1,2 V rms single ended, 2,4 Volt balanced. (no apamps, no transistors, no extra power supplies etc... )
Therefore no comparison between other designs in regard to optimum Rload is possible. More then 133Ohm is realy not advicable. Lower is OK, but you loose output voltage. Distortion is like -60dB, so mission completed I would say
on the Rload, well my design goal was to get max output at low distortion, hence I use 8 Volts supply voltage and 6k Bias resistor, where ALL other 1794 designs use 5 Volt and datasheet 10k...
I get 1,2 V rms single ended, 2,4 Volt balanced. (no apamps, no transistors, no extra power supplies etc... )
Therefore no comparison between other designs in regard to optimum Rload is possible. More then 133Ohm is realy not advicable. Lower is OK, but you loose output voltage. Distortion is like -60dB, so mission completed I would say
My Twisted Pear spdif "transceiver" (WM8804) is working fine here with a DDDAC having 2 dac boards.
If I upgrade to 4 dac boards, should I be worried about it?
I'm using TP Otto II I2S switch between spidf board (and waveIO) and DDDAC.
Don't know if it matters...
DDDAC1794S (note the "S")
Tomorrow is test day with my Audio friends. Just wanted to share latest Info on the SPDIF input and multiple decks. Did some final in-house tests with the following Setup (see Image):
Double power supply, the latest 384 kHz WaveIO with Version 2.15 Drivers, the new DDDA1794S (s for spdif ) and.... a preview of a TVC, based on my own Sowter transformer
So far everything works 100%. USB up to 384kHz, the spdif up to 192kHz and all with 8 decks and no HF compensation
The standard DDDAC 12 Volt power supply can feed as expected 8 decks, but it is the limit. Current is aprox 950mA when playing high resolution Music. Tranformer and Heatsink become like 45 degrees.
Will report back over the weekend on the sonic side of things
I will also publish the first circuits PDF, so you can see how I implemented the WM8804...
Tomorrow is test day with my Audio friends. Just wanted to share latest Info on the SPDIF input and multiple decks. Did some final in-house tests with the following Setup (see Image):
Double power supply, the latest 384 kHz WaveIO with Version 2.15 Drivers, the new DDDA1794S (s for spdif
) and.... a preview of a TVC, based on my own Sowter transformer So far everything works 100%. USB up to 384kHz, the spdif up to 192kHz and all with 8 decks and no HF compensation
The standard DDDAC 12 Volt power supply can feed as expected 8 decks, but it is the limit. Current is aprox 950mA when playing high resolution Music. Tranformer and Heatsink become like 45 degrees.
Will report back over the weekend on the sonic side of things
I will also publish the first circuits PDF, so you can see how I implemented the WM8804...
Attachments
no pot... a TVC (Transformer Volume Control). In this case 12 secundairy windings. Specially at normal listening levels, this results in very low output impedance, driving the next stage with extreme ease. Result is very detailed Sound
on the price, still need to calculate a bit
I hope no surprise, that a board with spdif functionality and plenty more SMD parts will not have the same cost... hence will cost more. But no worries, the other board will still be available for those who have no need for SPDIF