My current DAC is based on two pairs of D60 transformers.
I use a separate chassis with Power Supplies (first stage PSUs) which acting like a charger for cells (second stage PSUs) of the DAC.
All the PSUs inside the DAC chassis are: 10 lines of LTO PSUs and one line of LifePo4+UCs. Full chain of the DAC is:
1. BeagleBoneBlack (BBB) is the EndPoint (via ethernet/LAN NAA protocol) for the HQPlayer Embeeded.
2. iancanada's fifopi+reclockpi
3. Andrea Mori's DRIXO 45/49MHz clocks + squarer/selection board -> is the SINGLE mclk for BBB' I2S initiation and for the fifo stage.
4. My I2S-PCM board
5. My PCM1704 DAC boards
6. i/v resistors (handmade) ->D60 SUT->JFET SE buffer->D60 SUT->JFET SE buffer
Short spec of my DAC:
1. LAN input: up to 32bit/384kHz or 16bit/768kHz (current is 16/768)
2. Output level: 0.35Vrms (adjustable by i/v resistor up to 1.4Vrms)
3. Output BW(-3dB): 0.7Hz-120kHz (LF depends from the output signal voltage level)
4. Output impedance: 9 Ohm (next amplifier stage is 300R of input impedance)
And here is the recording on to the ribbon mics of my DAC in my room/stereo sysytem.
I use a separate chassis with Power Supplies (first stage PSUs) which acting like a charger for cells (second stage PSUs) of the DAC.
All the PSUs inside the DAC chassis are: 10 lines of LTO PSUs and one line of LifePo4+UCs. Full chain of the DAC is:
1. BeagleBoneBlack (BBB) is the EndPoint (via ethernet/LAN NAA protocol) for the HQPlayer Embeeded.
2. iancanada's fifopi+reclockpi
3. Andrea Mori's DRIXO 45/49MHz clocks + squarer/selection board -> is the SINGLE mclk for BBB' I2S initiation and for the fifo stage.
4. My I2S-PCM board
5. My PCM1704 DAC boards
6. i/v resistors (handmade) ->D60 SUT->JFET SE buffer->D60 SUT->JFET SE buffer
Short spec of my DAC:
1. LAN input: up to 32bit/384kHz or 16bit/768kHz (current is 16/768)
2. Output level: 0.35Vrms (adjustable by i/v resistor up to 1.4Vrms)
3. Output BW(-3dB): 0.7Hz-120kHz (LF depends from the output signal voltage level)
4. Output impedance: 9 Ohm (next amplifier stage is 300R of input impedance)
And here is the recording on to the ribbon mics of my DAC in my room/stereo sysytem.
Hello Ivan, Happy New Year. I am lead to your post from watching the Gabster D11 dac/streamer video. Tempted to build the model. My system today consist of a Innuos entrylevel streamer with a optinal linear power supply. This is connected to a dac from MHDT Labs. It use the PCM1704 chip followed by a buffer tube and coupling capacitior. While I like the sound of the PCM1704 and have fun rolling some tubes I know that I dont use the full potential of the converter chip. The psu could be better and infact the tubes make more noise than good are. My idea is to build a better psu and skip the tubes for replacing them with a transformer or active buffer stage. The MHDT runs without filter etc. Now reading your post and especialy the lates one where you show your dac I would like to ask if you sell similar versions? Please PM so we can have a quick talk. Secondary you could maybe advise me which transformers of your I should use to replace the tube buffer……? Br Mike
Vivaldi. Four Seasons. L'Inverno the Winter Allegro Non Molto.
Here is the direct recording from my DAC to Zoom H8 recorder. I have added 300R resistor right across the input inlets of the recorder to imitate how my DAC can work on to a high impedance headphones. BTW this recording sounds great in the headphones (kind of binaural recording). The Drottningholm Baroque Ensemble plays on original Baroque instruments so enjoy the special emotional atmosphere which was created using the instruments of Vivaldi's time.
Here is the direct recording from my DAC to Zoom H8 recorder. I have added 300R resistor right across the input inlets of the recorder to imitate how my DAC can work on to a high impedance headphones. BTW this recording sounds great in the headphones (kind of binaural recording). The Drottningholm Baroque Ensemble plays on original Baroque instruments so enjoy the special emotional atmosphere which was created using the instruments of Vivaldi's time.
Hello Ivan,
here is my review of your transformers:
My DAC configuration is PCM56 (personal design)->Transformer 1:10 (D60 - bigger ones)->6SN7 grounded cathode gain stage + 6080 grounded cathode gain stage.
Your I/V Transformers are very linear, not accentuating any frequency range. Also very very transparent. Any change in PSU, resistors, capacitor or any other component on DAC is clearly heard. Sound is very fast, music have more tonal colours than using transistor I/V stage. Also there is clear improvement in scene rendering in comparison with transistor I/V... musical scene with transformers is much more extended to depth and much clearer.
I have had experience with using MC transformer as I/V transformer in past, and there was exactly two problems... little bit of slowiness of sound and not enough of deep bass. So this was my primary concerns when considering your transformers. Fortunatelly, your trafos have great bass, on par with transistor I/V, and also I didn't experienced slowness of sound.
So after 5 month of use I can say, that your trafos are fantastic, and I'm not regretting my investment. Even though they wasn't cheap
Kamil
here is my review of your transformers:
My DAC configuration is PCM56 (personal design)->Transformer 1:10 (D60 - bigger ones)->6SN7 grounded cathode gain stage + 6080 grounded cathode gain stage.
Your I/V Transformers are very linear, not accentuating any frequency range. Also very very transparent. Any change in PSU, resistors, capacitor or any other component on DAC is clearly heard. Sound is very fast, music have more tonal colours than using transistor I/V stage. Also there is clear improvement in scene rendering in comparison with transistor I/V... musical scene with transformers is much more extended to depth and much clearer.
I have had experience with using MC transformer as I/V transformer in past, and there was exactly two problems... little bit of slowiness of sound and not enough of deep bass. So this was my primary concerns when considering your transformers. Fortunatelly, your trafos have great bass, on par with transistor I/V, and also I didn't experienced slowness of sound.
So after 5 month of use I can say, that your trafos are fantastic, and I'm not regretting my investment. Even though they wasn't cheap
Kamil
Hello Ivan,
using your smaller Transformers (1:7.7) for IANs Dual Mono DAC is very pleasing. Like it better compared to Buffalo IIIpro (9038pro) with mercury I/V stage.
The DAC is playing to a Tube-Preamp with 44 kOhm input impedance (for balanced input). As per recommendation from the manufacturer of the Preamp it would be better to use the volume setting of the pre amp in the middle positions. So I tried to vary the resistor values on the older transformer board for Ian DAC to get there. I started with 4 kOhm (your recommendation) lowered it to 2 kOhm (still to loud) an then to 1 kOhm. 1 kOhm is still a bit loud, but I did not go further down as you said the transformers might start oscillating.
Now my question here: If I change the resistors to the primary side for the same output I would go 1/60 of 1000OHM = 17 OHM. Could I go further down on primary side (say 10 OHM) or is this bad too (oscillation?)?
Regards
Branko
using your smaller Transformers (1:7.7) for IANs Dual Mono DAC is very pleasing. Like it better compared to Buffalo IIIpro (9038pro) with mercury I/V stage.
The DAC is playing to a Tube-Preamp with 44 kOhm input impedance (for balanced input). As per recommendation from the manufacturer of the Preamp it would be better to use the volume setting of the pre amp in the middle positions. So I tried to vary the resistor values on the older transformer board for Ian DAC to get there. I started with 4 kOhm (your recommendation) lowered it to 2 kOhm (still to loud) an then to 1 kOhm. 1 kOhm is still a bit loud, but I did not go further down as you said the transformers might start oscillating.
Now my question here: If I change the resistors to the primary side for the same output I would go 1/60 of 1000OHM = 17 OHM. Could I go further down on primary side (say 10 OHM) or is this bad too (oscillation?)?
Regards
Branko
Hello Branko,
Not oscillation but overdamping (mechanistical sound). But in case of i/v resistor at primary side there should be no harm of use low value resistors across the secondary. You can use as low i/v resistor value (across the primary coil) as you can (possible in terms of loudness). For 10 Ohm i/v you can use down to equal value resistor across the secondary - 600R. Impedance seen by DAC itself will be 10||(600/59)=10||10=5 (Ohm). Or you can use 10 Ohm across the primary (or lower) and 1/2/5/10k across the secondary - it is up to you. But the quality of the i/v resistor across the primary coil is very urgent I recommend to use a wirewound resistors. Sound will be formed mostly by this low value resistor self sound signature.
Good luck!
Ivan.
Not oscillation but overdamping (mechanistical sound). But in case of i/v resistor at primary side there should be no harm of use low value resistors across the secondary. You can use as low i/v resistor value (across the primary coil) as you can (possible in terms of loudness). For 10 Ohm i/v you can use down to equal value resistor across the secondary - 600R. Impedance seen by DAC itself will be 10||(600/59)=10||10=5 (Ohm). Or you can use 10 Ohm across the primary (or lower) and 1/2/5/10k across the secondary - it is up to you. But the quality of the i/v resistor across the primary coil is very urgent I recommend to use a wirewound resistors. Sound will be formed mostly by this low value resistor self sound signature.
Good luck!
Ivan.
Hello Ivan,
thank you for your patience.
But to clear thing out little bit more: do I then have to use resistor only on primary side (lets say 10 Ohm) or also corespondent resistor on secondary (in this case 600 Ohm). Or if I should use resistor on primary an secondary how should the relation be best (7.7*7.7 ?) or higher?
Because at the moment I use only resistor (1000 Ohm) on secondary side. As your older version of pcb for Ian Dac which I use has only one place for resistor.
What I want to do is to find a value setting in terms of loudness (middle setting of volume knob from preamp) with „cheap“ resistor. And then to buy the right values of better resistors. But I do not want to sacrifice sound for lower volume. As with cheap resistor of 1000 Ohm on secondary it sounds very pleasing.
Branko
thank you for your patience.
But to clear thing out little bit more: do I then have to use resistor only on primary side (lets say 10 Ohm) or also corespondent resistor on secondary (in this case 600 Ohm). Or if I should use resistor on primary an secondary how should the relation be best (7.7*7.7 ?) or higher?
Because at the moment I use only resistor (1000 Ohm) on secondary side. As your older version of pcb for Ian Dac which I use has only one place for resistor.
What I want to do is to find a value setting in terms of loudness (middle setting of volume knob from preamp) with „cheap“ resistor. And then to buy the right values of better resistors. But I do not want to sacrifice sound for lower volume. As with cheap resistor of 1000 Ohm on secondary it sounds very pleasing.
Branko
Its OK. 1000 ohm means that your DAC sees ~17 Ohm. So it is the main point: what value is seen by the DAC. 8 Ohm means -6dB in your case from the existing volume point. 4 Ohm means -12dB. So if -12dB is wanted then you can use 8 Ohm across the primary and 8*59=~470R across the secondary. In this case the impedances at primary and secondary sides will be equally splitted on two parts. Or you can use 6R across the primary and 700R across the secondary. Or 5R and 1k2 and so on... It is up to you and the sound (signature) you will prefer.
1000 ohm means that your DAC sees ~17 Ohm. So it is the main point: what value is seen by the DAC. 8 Ohm means -6dB in your case from the existing volume point. 4 Ohm means -12dB. So if -12dB is wanted then you can use 8 Ohm across the primary and 8*59=~470R across the secondary. In this case the impedances at primary and secondary sides will be equally splitted on two parts. Or you can use 6R across the primary and 700R across the secondary. Or 5R and 1k2 and so on... It is up to you and the sound (signature) you will prefer.Thank you once more. Will try.
As you later seem to prefer resistors at both primary and secondary coil: would for my momentary solution (only 1000 Ohm on secondary) be “better“ to use 1000/60 Ohm on primary and 1000 Ohm on secondary with same loudness level?
What is the price for your resistors (i.e. 8R)?
Regards
Branko
As you later seem to prefer resistors at both primary and secondary coil: would for my momentary solution (only 1000 Ohm on secondary) be “better“ to use 1000/60 Ohm on primary and 1000 Ohm on secondary with same loudness level?
What is the price for your resistors (i.e. 8R)?
Regards
Branko
1000/60 with 1000 means that you will get -6dB from existing level as 1000/60 across the primary is already means 1000 across secondary even without resistor across the secondary. To be at the same level you will need to double both values. 2000/60:2000 then.
I do not selling them separately. Sometime I offering them with D60 transformers.