Hello,
I'm thinking about giving a tube output stage to my little CS4397-based dac.
I found the attached Lampizator 300b scheme for V-out dacs, but I dont know how to connect dac outputs to the tube, since the cs4397 chip has differential outputs, and 300b is a single triode.
I found another schemes, e.g. Broskie Cathode Follower, which uses a dual triode per channel, which allows you to connect + and - channel outputs to each triode.
So is it possible to have differential outputs with a single triode tube? How should the connections be in this case?
I'm currently using a 9 volt walwart supply to power on the dac, but I plan to make a choke-regulated power supply.
Thank you all!
I'm thinking about giving a tube output stage to my little CS4397-based dac.
I found the attached Lampizator 300b scheme for V-out dacs, but I dont know how to connect dac outputs to the tube, since the cs4397 chip has differential outputs, and 300b is a single triode.
I found another schemes, e.g. Broskie Cathode Follower, which uses a dual triode per channel, which allows you to connect + and - channel outputs to each triode.
So is it possible to have differential outputs with a single triode tube? How should the connections be in this case?
I'm currently using a 9 volt walwart supply to power on the dac, but I plan to make a choke-regulated power supply.
Thank you all!
Attachments
Hi,
By a LTP did you mean a line transformer?
I really would like to build the project with the tubes. In fact, I Already have a pair of type 45 tubes, wich are well suitable for this project.
Tks!!
Nilton
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A split-load would do it but it has a single ended input. For diff in diff out have a look at the backend of the RTP3 from VSE.
Most of the easily available tubes (let’s not forget the replacements in future) are indirectly heated.
The Dac chip has a differential output. With a dual triode (ie two single triodes in a single glass envelope) this would work as a differential amp.
What you will need todo is work out the gain required, impedance matching etc. it looks like you probably want a buffer with a little voltage amplification but not much. A single ended amp and cf could be done with two dual triodes tubes (triode amp+cf). If you want to use the differential output then a LTP+cf pair for each channel will result in four tubes. If you just take one single ended output from the LTP the. You could do it I. Three tubes but with a SE outout. A final alternative is use a audio diff-to-SE transformer.. but then the cost will be rivalling a tube.
Personally I would do the differential output. Then I would only connect one or the signal pins if you want an SE output.
Lastly power supply to the tube. You have a massive 19H choke - is that is for both channels? That’s going to be a big block of iron. So my question here is - how are you keeping the channel separation free from cross talk via the B+?
To give you an idea, I have a 320V rail using 45mA class A and two 3H 500mA capable chokes in CLCLC arrangement after a solid state rectifier. Ripple is stupidly low. Another alternative is using something like Tom Christians Maida regulator. It’s floating so will regulate to ludicrous levels (for a tube) but just be weary that once you start regulating everything needs it..
The Dac chip has a differential output. With a dual triode (ie two single triodes in a single glass envelope) this would work as a differential amp.
What you will need todo is work out the gain required, impedance matching etc. it looks like you probably want a buffer with a little voltage amplification but not much. A single ended amp and cf could be done with two dual triodes tubes (triode amp+cf). If you want to use the differential output then a LTP+cf pair for each channel will result in four tubes. If you just take one single ended output from the LTP the. You could do it I. Three tubes but with a SE outout. A final alternative is use a audio diff-to-SE transformer.. but then the cost will be rivalling a tube.
Personally I would do the differential output. Then I would only connect one or the signal pins if you want an SE output.
Lastly power supply to the tube. You have a massive 19H choke - is that is for both channels? That’s going to be a big block of iron. So my question here is - how are you keeping the channel separation free from cross talk via the B+?
To give you an idea, I have a 320V rail using 45mA class A and two 3H 500mA capable chokes in CLCLC arrangement after a solid state rectifier. Ripple is stupidly low. Another alternative is using something like Tom Christians Maida regulator. It’s floating so will regulate to ludicrous levels (for a tube) but just be weary that once you start regulating everything needs it..
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