I know sowter is offering some transformers for current output DACs but they are too expensive for experimenting.
So here we are, has someone used something else? I am looking at cinemag CMOB-3 and CMMI-8B3 for example....
So here we are, has someone used something else? I am looking at cinemag CMOB-3 and CMMI-8B3 for example....
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I built my NOS AD1865 using the best parts i can afford. Using the sowter 9545 with OOC wire no less together with rhopoint passive i/v resistor to a tube output. The sowter 9545 is use as a balance to single but it can also use as balanced out.
No regrets... 🙂
No regrets... 🙂
I don't know of any hifi quality (amorphous or high nickel core) line level output transformers that could be characterized as cheap. You could save some cost, without quality sacrifice, the lower is the output impedance of the driving circuit, and/or the lower is the maximum trnasformer signal amplitude. Those two parameters greatly determine the cost of an audio transformer.
In your specific implementation, the passive I/V ressistors will mostly determine how low the driving source impedance will be. However, because you are using an active output stage (I'll assume it provides voltage gain) you should be able to find cost savings due to a maximum required undistorted transformer signal level that's reduced by a factor equal to the active stage's gain - compared to a transformer designed for direct line level output.
In your specific implementation, the passive I/V ressistors will mostly determine how low the driving source impedance will be. However, because you are using an active output stage (I'll assume it provides voltage gain) you should be able to find cost savings due to a maximum required undistorted transformer signal level that's reduced by a factor equal to the active stage's gain - compared to a transformer designed for direct line level output.
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Thank you for the info guys...I am aware of the fact that good stuf costs more money but
this thread should deal whit the dilema of finding cheaper solutions to experiment whit and
maybe sound similar....
On ebay there is something like this available: ST-20600-OB
Also from edcor maybe something available or as I pointed to were the cinemags...
this thread should deal whit the dilema of finding cheaper solutions to experiment whit and
maybe sound similar....
On ebay there is something like this available: ST-20600-OB
Also from edcor maybe something available or as I pointed to were the cinemags...
I wound my own DAC output trafos using ferrite PQ cores. Price of parts - around $2 each, lots of labour time though.
Perhaps, then, the first issue to be addressed is why exactly do you want to employ transformer coupling of the AD1865?
This way its better isolation from DAC to the output circuit,
also you get a step up of signal...I used only tube output stage and it wasnt the max what I
expected...I also tried a simple Jfet stage whit mosfet source follower and it wasnt bad at all
but something is still missing...
also you get a step up of signal...I used only tube output stage and it wasnt the max what I
expected...I also tried a simple Jfet stage whit mosfet source follower and it wasnt bad at all
but something is still missing...
Happy to oblige - what voltage levels do you want to interface? Then I can suggest particular cores and wire gauges and numbers of turns.
A few different ones. The first pair I made interfaced my TDA1387 DAC direct to IEMS - this meant a step-down ratio around 4:1 I think. About 500mV (unbalanced) to the 'phones and 2V (balanced) on the DAC side.
The second pair I substituted for the first when I modded the DAC to drive into active speakers rather than IEMS, so they went to just under 2:1. The third pair interface between a balanced JFET buffer and active speakers and these are 1:1, going 2V balanced to 2V unbalanced.
I used 60R but there wasn't much current, according to the seller these are actually designed for the pcm1794. In the end I used them with 4x parallel TDA1387, the sound is fantastic (150R iv resistors).
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