Forgive my ignorance, I do not quite understand what exactly are "voltage transformers and current transformers" . When a voltage is applied on the primary side of a transformer, an induced voltage will appear on secondary side. When a load is placed on the secondary side, a current will flow. That's the the whole idea of a transformer. Both voltage and current will be induced on the secondary side of the transformer.
For a real world transformer, there are three kind of losses, copper loss, iron loss and loss due to eddy currents. The DC resistance of the coil is mainly responsible for the copper loss. Higher the copper losses, more signal is "wasted". More turns in the secondary coil of the transformer, higher the inductance. Higher the inductance, higher the reactance ==> higher the impedance. For efficient energy transfer (the signal), the impedances of the output of the secondary coil and the input of the device (which is connecting to the secondary coil) should be within a certain range. Definitely that's something one has to watch out. What exactly is this range, it depends on the transformer and the device it connects to and can be determined experimentally.
Regards,
Agreed, transformers are transformers. The term current transformer usually refers to a transformer that is optimized and characterized for current measurements, such as described here:Current transformer - Wikipedia
But, they are still transformers and standard transformer models apply to them.
EDIT: Corrected Link
But, they are still transformers and standard transformer models apply to them.
EDIT: Corrected Link
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The output current of the DAC is part of its design parameter and not much we can do about it, am I right?
I am baffled by this current/voltage mode thing
. There are always voltage and current present at the DAC output. I guess one can manipulate the amount of current wrt voltage. How does one know how much current output is good, how little is bad? It seems to me (correct me if I am wrong) that matching the output impedance of the DAC with the input impedance of the device to which the DAC is connected to is more important. Regards,
Regards
Transformer is transformer, you are right. Transformer - is a device that transforms impedances. But the source can be current or voltage, right? Let's going away for a minute from this kind of DAC with its "hybrid" output (ES9018, I don't really understand how it can provide pure current mode) but let's refer to the old one R2R DAC. PCM63 for example (http://www.sowter.co.uk/dacinfo/PCM63.pdf). It has only current output of +/-2mA, there is no voltage mode at all. Say, if you will short the current output to the ground, you will not get any Voltage, right? But the current of signal is still there, at full scale it is +/-2mA with the best SQ. Question - is how to grab it and bring to the consumer device without affecting to the output of DAC. It is necessary to force the DAC to work on the ground but it is still necessary to take somehow the whole signal. 1465\9545 is a good choice I guess. But. The more pure (without noise in small signals) dynamic range or the higher the volume of the signal at the output, the better. In this regard, to save small signals from the noise of PSU, I prefer to get the maximum possible volume level from the DAC. Compared to Sowter's transformer I have better choice I hope. But to be honest, if it will be possible in future, I would like to get possibility to compare SQ with such branded devices like LL or Sowter...
One more thing about this board\DAC. It is may be some kind of joke... But I can not force it to play square signals lower than 7kHz within 384k SR (through I2S). I have a file with the squared signals swept from 0 to 24kHz. And the DAC simply keeps silent untill the freq get up to ~7kHz. After that point it plays without problems till the end of file, till 24kHz. There is no problems when it's playing similar sinusoidal signals from 0Hz and higher. But for square signals lower ~7kHz (for 384k SR) DAC periodically loses the sync (Lock led starts "flashing"). But everything is OK with 192k SR.
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It seems that you have other things going on on that boards that probably has much more effect than I or V out.... ?
My bet is that of you do two implementation identical except for the I & V thing, you don't have much aural difference left... I have done my share of testing with a 9016...
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There is a 10k pot doing better job
It's funny to regulate Volume by fingers. First finger of one hand is on VOL pin, and second finger on +15V for decreasing or on the GND pin to increase.
I have mentioned earlier, see my post #28 (and check the circles), all the consumers are on the very same 3.3V, and shared with all the power legs of the DAC chip (digital and analog). Very bad...
From my point of view, try better power supply, better regulators (i will have one soon...) i will try to change capacitors (I dont expect any change...) ans opamp makes small change especially if you try better ones (LME49720, OPA627, MUSES8920 - this one i will try this week) , this card bested more expensive cards for Rpi like Mambo LS, Kali 2.1 or Audioph. 9028q2m so I am satisfied , only dont like (sometimes) too much transparent sound in highs...but this also depends on quality of record.. best option will be wait for better implementation of 9038q2m...from Allo or another company...
We have been testing our card for over one month and optimized the components and filters.
Hello, now i am building discrete HDAM differential circuit with its own diamond buffer onto output to replace simple buffer LPF which is now used onto DAC. Waiting for dual FET transistors 2SK389... so hope it would help... discete solution would help...
