You don't need to use any DC-offset for 1541 using my transformers as the DCR of primary coil is very small and will not lead to any sufficient DC offset presence on it from 1541.
Anyway it is safe even if it will be presented for a few seconds
Hi!
Sorry for my very beginner question...🙁
I intend to build a tda1541 dac using the Analogmetric board (called GreenDac by Lukasz Fikus from Lampizator), Im thinking about using 2 x tda1541 in parallel, and would like to understand if the transformers replace the i/v resistors, or should it be used after the i/v conversion with resistors.
I'm analyzing 2 output stages (both with the AD1865 dac, but if I'm not wrong, the output stage could be the same...), and I would really appreciate your opinion:
The first is the Dac End from Andrea Ciuffoli, which uses i/v resistors and then an e182cc tube to amplify the signal, followed by transformers to adjust the impedance.
The second is the Audio Note Dac2.1, which apparently made the i/v conversion with transformers (without using i/v resistors), and then the signal is sent to 6922 valves in the analog stage.
What seems to be the best choice in your opinion? And which of your transformers do you recommend for 2 x tda1541 and parallel?
Thank you very much!!
Hi.
The one only correct way in terms of transformers to use with any current output DAC type like 1865 or 1541 is to force the DAC chip itself to work on to a very low impedance like 1-20R, because the best case to work for any current source is on to a Zero impedance, i.e. 0 Ohms. So any impedances like 100R and more are simply will be too far from the predicted by the DAC's specs SNR/THD/DR/SINAD parameters. AN 2.1 in this terms uses very high impedance seen by 1865, thus far from the best initially. Low value resistor as IV is the best case. Resistor type is very urgent. I recommend to use resistors like AN tantalum, Vishay Z-Foil, wire-wound like mils and other audiophile types. Step Up Transformer after low IV resistor doing the impedances transformation for hundreds times (or even thousand+) depending on its turns ratio - aka doing a voltage amplification (power amplification is not happening due to proportional current decreasing). The impedance (reflected from iv resistor) after transformer is very high for a normal signal transferring over the cables, thus you need to lower the impedance after SUT using current amplifier. It can be a tube follower or transistors follower. I like jfets due to their better clarity and resolution. There is no need to use any DC-blocking circuits then like in tubes (caps or output trafos) as well as the PSU is simplier as for me. I prefer to deal with jfets follower based on 2SK170/2SJ74 pair which works in A class (SE mode for RCA or 2xSE aka BAL for XLR). 1541 signal is 2 times stronger than 1865: 4mApp vs 2mApp. Means that you can achieve the needed voltage swing on 1541 using 2 lower seen impedance (lower iv or lower turns ratio).
So best case I found is: IVresistor->SUT->Follower.
I recommend to use 1:40 D60 trafos+jfet follower.
Thanks.
Ivan.
Silver version (OCC 5N) is available for ordering. Initially designed for LOMC cartridges, thus suitable as an after-DAC transformers as well.
Actual prices: https://ivxformers.com
Actual prices: https://ivxformers.com
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Hi Bisesik
After some years of enjoying the music with your transformers using 4K resistors on the secondary coils only, I was interested to read recently that a combination of resistors on the primary and secondary coils has proven worth while, providing the primary is of high quality.
I have an old version 3 Ian Canada board with1:22 transformers over Ian's 9038Q2MPi Dual Mono Dac.
My question, like so many others, is regarding the value of those resistors with the following amp having an impedance of 47K.
Given the cost of foil resistors and my lack of ability to do the math I would just like confirmation that the primary is 100R and the secondaries 13K.
Or not.
Cheers
After some years of enjoying the music with your transformers using 4K resistors on the secondary coils only, I was interested to read recently that a combination of resistors on the primary and secondary coils has proven worth while, providing the primary is of high quality.
I have an old version 3 Ian Canada board with1:22 transformers over Ian's 9038Q2MPi Dual Mono Dac.
My question, like so many others, is regarding the value of those resistors with the following amp having an impedance of 47K.
Given the cost of foil resistors and my lack of ability to do the math I would just like confirmation that the primary is 100R and the secondaries 13K.
Or not.
Cheers
Hi,
4k across secondary is 4000/22/22=8.26R across the primary. Use 18R across primary and 18*22*22=8.7k across secondary (to get the same level as you have with 4k across the secondary only)
Ivan.
4k across secondary is 4000/22/22=8.26R across the primary. Use 18R across primary and 18*22*22=8.7k across secondary (to get the same level as you have with 4k across the secondary only)
Ivan.
I have got a pair of D60 transformers for sale. Please check the Swap Meet section or drop me a PM.
Have someone tryed different resistor on V out trafo 1:1 this are R1 and R2 .. i use now 5kohm .. and it sound also good .. my Dac is Ak4493
1... someone tryed without those resistor
2,,, if i like to try Joe Rasmussen Zobel filter on output trafo, shall i still use R1 and R2 on the Trafo output (parallel over Bisesik trafo V out )
1... someone tryed without those resistor
2,,, if i like to try Joe Rasmussen Zobel filter on output trafo, shall i still use R1 and R2 on the Trafo output (parallel over Bisesik trafo V out )
i can give a update on resistor
i have now tryed with and without resistor on output , trafo
they mesure distortion nearly the same ,,,,i measure on output on my preamp
but i prefer the sound without the resistor ( i use Joe R zobel)
so, can it be, that the impedance the Dac ak4493 see , is better with only the 20kohm balanced from the preamp input..... i must try to figure this out
i have now tryed with and without resistor on output , trafo
they mesure distortion nearly the same ,,,,i measure on output on my preamp
but i prefer the sound without the resistor ( i use Joe R zobel)
so, can it be, that the impedance the Dac ak4493 see , is better with only the 20kohm balanced from the preamp input..... i must try to figure this out
Hi Ivan, I'm building a DSC Dac at the moment and I know others have had great success using your transformers and I'm keen to do the same.
Could you let me know what would be the best of yours to order and what options there might be that would work? Also, I believe I've seen an output circuit board that would fit the DSC 2.5.2, would that be possible as well?
Thanks
Elliot
Could you let me know what would be the best of yours to order and what options there might be that would work? Also, I believe I've seen an output circuit board that would fit the DSC 2.5.2, would that be possible as well?
Thanks
Elliot
My D60 SUT trafos will work just fine with any DSC version. I have no PCBs with D60 trafos that can be fitted to DSC 2.5/2.6 boards as you saw versions that was done for D46 trafos which I have discontinued.
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Great thanks for that, my feeling is I'd be looking at either the copper:copper or the silver:copper, from your experience with others, what would be the best turns ratio for this do you think? Would that be possible on both of those?
For the board, would it be workable / feasible if I were to "scale up" the D46 board? Perhaps it would need redoing the pinning as well...
For the board, would it be workable / feasible if I were to "scale up" the D46 board? Perhaps it would need redoing the pinning as well...
I think there is no real limits for the turns ratio and I would go for from 1:16 to 1:24. But, but... The output impedance in this case will be high and better to lower it down using a jfet buffers.
I can share the PCBs layouts (sprint layout SW files) and you can make all you want to prepare the needed gerbers, you are welcome in this terms if you can do such.
Ivan, do you a still make the smaller transformers? I am interested in a pair 1: 0.5-0.5. If you have them, how much are they?Thanks!