Hi Diyers,
I have an old Korean made DAC based on CS4397-KSZ chip, which has differential voltage outputs, and Im wondering about giving him a tube output stage.
I liked both BCF-2 and ACF-2 circuits from Tubecad.com (for sale at Tube-Based Buffers) , but Im not sure about which one is the more suitable for my DAC, since according to Balanced and Differential , Differential and Balanced outputs are not the same thing.
So, my doubts are:
Are the differential outputs from the CS4397 also balanced?
If so, the best option should be the BCF-2 since it has + and - inputs for each channel (dual triode, connecting pins 23 & 24 to V1 and pins 19 & 20 to V2) ?
If ACF-2 is the best option, how should the dac outputs be connected?
All help is welcome!
Tks and rgds
Nilton
I have an old Korean made DAC based on CS4397-KSZ chip, which has differential voltage outputs, and Im wondering about giving him a tube output stage.
I liked both BCF-2 and ACF-2 circuits from Tubecad.com (for sale at Tube-Based Buffers) , but Im not sure about which one is the more suitable for my DAC, since according to Balanced and Differential , Differential and Balanced outputs are not the same thing.
So, my doubts are:
Are the differential outputs from the CS4397 also balanced?
If so, the best option should be the BCF-2 since it has + and - inputs for each channel (dual triode, connecting pins 23 & 24 to V1 and pins 19 & 20 to V2) ?
If ACF-2 is the best option, how should the dac outputs be connected?
All help is welcome!
Tks and rgds
Nilton
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Need more information.
The DAC chip output is differential, but that doesn't mean the board output is. I see an 8 pin socketed chip. Is that an op amp? Is the board output XLR or RCA?
The DAC chip output is differential, but that doesn't mean the board output is. I see an 8 pin socketed chip. Is that an op amp? Is the board output XLR or RCA?
Hi leadbelly,
Yes, it is an opamp Muses8920, which I used to replace the stock LT1364. Outputs are RCA.
Yes, it is an opamp Muses8920, which I used to replace the stock LT1364. Outputs are RCA.
Well then the board outputs are neither balanced nor differential, as is expected. The opamp is buffering the DAC chip. You don't NEED anything more. If and which tube buffer you choose to add is purely up to you.
My idea is exactly to replace the opamp by a tube stage, which will also work as a preamp since I would add a volume control to it.
In this case, can I only lift up the dac output pins and connect them to the tube´s grids, then connect buffer outputs to RCAs?
If I choose the ACF-2 buffer ( the fourth image) which has only 1 input per channel, what would the connections be since dac has 4 output pins?
tks
In this case, can I only lift up the dac output pins and connect them to the tube´s grids, then connect buffer outputs to RCAs?
If I choose the ACF-2 buffer ( the fourth image) which has only 1 input per channel, what would the connections be since dac has 4 output pins?
tks
Well, you can try that, but it is a lot of effort and expense and may simply not work well at all.
The op amp section is likely not just a bare op amp stage, it likely is also one or more filters. If you are handy with a meter it would be best to make a schematic of the analog output stage. If you connect the tube buffer to the op amp pins, the filter(s) will behave differently because the impedance has changed.
The DAC chip has little drive, and asking it to drive a cable's capacitance all the way to another board may result in audible HF rolloff.
The op amp section is likely not just a bare op amp stage, it likely is also one or more filters. If you are handy with a meter it would be best to make a schematic of the analog output stage. If you connect the tube buffer to the op amp pins, the filter(s) will behave differently because the impedance has changed.
The DAC chip has little drive, and asking it to drive a cable's capacitance all the way to another board may result in audible HF rolloff.