Has anybody seen these tube output stages for dac usage?
SPDIF output tube stage,6S31B | eBay
Tube output stage for cd player or dac upgrade | eBay
I have a gigaworks big dac but with transformers in the output stage not opamps. I was thinking about a universal tube output stage available elsewhere but these are cheaper (although I'm not sure about compatibility etc).
Just asking if anybody else had implemented either of these boards in their diy dacs.
Best
If the links dont work for some reason then of course "tube output stage" will work (make sure "international sellers" is enabled)
SPDIF output tube stage,6S31B | eBay
Tube output stage for cd player or dac upgrade | eBay
I have a gigaworks big dac but with transformers in the output stage not opamps. I was thinking about a universal tube output stage available elsewhere but these are cheaper (although I'm not sure about compatibility etc).
Just asking if anybody else had implemented either of these boards in their diy dacs.
Best
If the links dont work for some reason then of course "tube output stage" will work (make sure "international sellers" is enabled)
No audio
thank you very much for reading this post and helping me out.
I brought 3 of these board and 1 of them has no sound
I had check :
thank you very much for reading this post and helping me out.
I brought 3 of these board and 1 of them has no sound
I had check :
- solder joint
- component values and orientation
- Opamp is ok
- and supply voltage +/- 18VDC and 13VDC
Attachments
thanks for the pic:
now i order the cm6631 kit which have spdif and I2S, but i think use only the spdif.
about the coupling transformer, the price is high so i use 0.22uf cap for coupling between the DAC and power amplifier.
i think to move to cd player instead the pc, maybe the quality is higher.
thanks
Use an ordinary divider at the output of the opamp... about 1/3 of the output voltage will do.
I want to make a tube buffer output for this DAC and I settled on a Broskie Cathode Follower or Unbalancer circuit. Now, I'd like to know if I need the Unbalancer circuit over the BCF as I read there's an extra voltage amplification stage in the Unbalancer. Is that needed? I am driving a small TA2020 amp at the moment, and I'll be experimenting with a tda7297 chip amp and maybe a lm3886 gainclone. Would I need the extra gain from the Unbalancer?
This is probably the AF section.
For example, an amplifier or preamplifier with:
1u input cap, 100k feedback resistor, 2k7 feedback-shunt and 220u nfb-shunt cap.
The bass error does not exist in that case.
Let's screw it up for the sake of understanding. . .
10u input cap, 22k feedback resistor, 680R feedback-shunt and 22u nfb-shunt cap.
That setting results in foldback because constipated. It does *more in than out* so you get epic 2nd harmonic distortion at the bass.
On this very bad, yet commonplace, example, if one added a bass booster, then turning up the bass knob would be met with the defeat of getting a lot of booming and almost no low bass clarity.
A little bit of this error is necessary for practicalities because. . .
If we arrange the feedback-shunt RC to actually reach 0hz, then it will do thud-only bass, which is a problem opposite of the boomer, but still has the problem of monotony. Indeed we will need to carefully choose a compromise or sort of make/break point in between the two problems so that there will not be monotony of any sort.
This is the H1/H2 balance of audio systems and it is critical that it be brought to an even balance rather than an extreme of one or the other.
For example the diyaudio.com Honey Badger amplifier has 220u||100n for feedback-shunt coupler cap, and with the given resistor values, this results in a great deal of loud booming and harsh loud treble that is totally suitable and vitally necessary for Outdoor prosound; however, for indoor home use, you should replace that 100n with a 220u, resulting in 220u||220u (hopefully identical models) and the lovely deep bass notes that are quite good Indoors. That, correctly, does not remove the error entirely, but it does deepen the bass and it quickly defeated a DC tracker alternative. Anyway, if the same pro amplifier is used both indoors and out, you'd probably want to install a switch so that both options are available. That would be a sort of h1/h2 or indoor/outdoor switch. This matter also applies to preamplifiers of any sort.
Anyway, before blaming the dac itself, we really should inspect the analog AF section to see if it is set for desired output or not. Albeit slightly more difficult to see, any small signal power decoupler cap is also an audio cap because your signal will go through the power decoupling caps the moment *before* you hear it, so those may also need inspected and the values adjusted when necessary. The decoulpers have a lot to do with midrange, but would probably not cause bass foldback 2nd order harmonic distortion. Necessarily, the capacity does exist (this is not impossible); however, it is far more likely for the AF (audio frequency) section is not adjusted for a favorable H1/H2 balance of bass.
The datasheet examples of most chip audio amplifiers of any size are usually inaccurate and indeed it is a fantastic and epic prank when they're accurate because I'd try everything else first. These things are probably at the output of your DAC and will definitely need inspected. Some DAC's have a high voltage output then followed by a chip amplifier set for maximum negative feedback so that it will perform as a buffer, which is a most grievous error and the rare case where you should not use a chip amplifier but rather a purpose made buffer instead. Or the alternative of using a diode clipper to protect the DAC from surges and then TWO audio amplifiers, allowing the differential DAC to facilitate a bridge amplifier will be much more entertaining than a quality blockade. Almost all audio amplifiers contain a phase splitter, but it is really crazy to have a balance to unbalanced converter at the output of your DAC and then a phase splitter, which is an unbalanced to balanced converter in the amplifier. That's bonkers. It could be nicer to bypass that whole section and allow the differential output DAC to drive the large signal amplifier without the redundant conversion processing.
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Sorry that I disagree with you on this point. A good amplifier for PA usage should be designed for excellent sound quality wherever it is used. Good PA amplifiers can be used in a good hifi system and sound wonderful. Example: Crest CA series amps - Linear power supply, huge transformers. Quality resistors and capacitors all over the boards. These amps dont compromise on sound quality. I know from personal experience that these amps are used in video post production houses, and as monitor amps in recording studios.
There are plenty of nasty PA amplifiers, as well as nasty PA speakers.
I dont think anyone is fooled into thinking that this sort of nasty gear is good, or that PA audio is meant to sound this way.
I tend to see the cheap nasty gear used in places that are too cheap to buy the good stuff, or the system has been designed by an idiot.
There are many nice sounding PA speakers and amplifiers - even good enough to use at home.
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It is neither cheap nor nasty. In fact it is designed to be easily adapted for your specific needs. I did not intend to make any sort of insult. However, the needs of indoors versus outdoors are different because of the presence or absence of walls, and it is really excellent that the Honey Badger amplifier can be adapted for either cause by swapping only one capacitor.
I was attempting to (and apparently failed) to address the issue of H1/H2 balance in analog audio. And the only compromise on sound quality is if you didn't do it. Therefore, it is not appropriate for the first move to be in blaming the DAC for it. My one and only point is that we should inspect the AF section first. It can be glorious, and that will not be in the datasheet, except for the very rare surprise.
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I wasnt insulted. But I still disagree with you. The point I am trying to make is that proper quality outdoor PA systems do not sound bad. A well designed PA system is designed from the microphones through to the speakers and everything in between. The system will be equalised for flat frequency response by the system designer and the FOH engineer will place his mix and perhaps some EQ on the overall sound, and sound quite wonderful if done properly.
If you are trying to say that most outdoor concerts are too loud, I agree with you on this point. Audio played too loud can be very objectionable. In which case move yourself to the distance away from the speakers that sounds best to you.
Some PA systems get run too loud into clipping and the compression drivers start to sound bad = harsh. This is more to do with an inadequately specified system or bad mixing by the FOH engineer.
I dont know who was blaming the DAC chip? I wasnt me.
Othewise I understood your comments in relation to H1/ H2, and agree.
If you are trying to say that most outdoor concerts are too loud, I agree with you on this point. Audio played too loud can be very objectionable. In which case move yourself to the distance away from the speakers that sounds best to you.
Some PA systems get run too loud into clipping and the compression drivers start to sound bad = harsh. This is more to do with an inadequately specified system or bad mixing by the FOH engineer.
I dont know who was blaming the DAC chip? I wasnt me.
Othewise I understood your comments in relation to H1/ H2, and agree.
Discussion: dont you think this can be rather involved process converting an amplifier with only unbalanced input to accept a balanced input?
Well, all of those things do contain a phase splitter, which is terribly redundant in the case of the DAC on this page.
EDIT:
I should have said: detrimentally redundant
EDIT2: That DAC was apparently made by an idealist and we have only to hook it up like that to realize the performance. It must replace the phase splitter. And if you do that, I suppose that you will be impressed. But otherwise the circuit doesn't make much sense and there could be some hardship in inserting the duplicate stages since the quality control effort may be both extreme and unnecessary.
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I've never thought that a phase splitter had very much detriment to the sound quality.
Tell me which phase splitter is worse for sound and why.
An unbalanced input balanced line driver. Eg. SSM2142
Two op amps configured as phase splitter.
A single transistor phase splitter.
?
I should wait for your reply, but I believe that there are more important things to worry about than the sonic effects of a phase spitter in my amplifier.
Tell me which phase splitter is worse for sound and why.
An unbalanced input balanced line driver. Eg. SSM2142
Two op amps configured as phase splitter.
A single transistor phase splitter.
?
I should wait for your reply, but I believe that there are more important things to worry about than the sonic effects of a phase spitter in my amplifier.
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Yet again, we don't have any disagreement. However, my point is that a phase splitter is detrimental when it is unnecessary. The DAC's on this page output much like bridge amp. That makes a phase splitter unnecessary because the output of the DAC is already split phase. This is probably a fundamental difference that should be used rather than processed twice.
I am unaware of any amplifier design with balanced input that does not use a phase spitter?
Can you suggest one?
The phase spitter serves many purposes.
Think about the situation when either hot or cold pin of the balanced input becomes open circuit.
What happens to the amp?
What happens to the ouput signal of the amp?
I think you will find that in real world situations you need the phase splitter.
Can you suggest one?
The phase spitter serves many purposes.
Think about the situation when either hot or cold pin of the balanced input becomes open circuit.
What happens to the amp?
What happens to the ouput signal of the amp?
I think you will find that in real world situations you need the phase splitter.
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I think you are forgetting one thing about AK4393/6. It is only a single DAC per channel and uses a built in op-amp on its output to generate the balanced signals. It is using a phase splitter!
If you really think phase splitters negatively affect sound then you should consider single output DAC chips with single end class A amplifiers. I don't think phase splitters hurt the sound at all. I think you are proposing a solution to a problem which does not exist.
Yes, you're right of course. My suggestion would only work with an amplifier that doesn't require feedback. Either that or an especially designed amplifier with 2 pairs input transistors instead of the single pair.
That is not so interesting because it is so much more fun to drive pairs of amplifiers with the differential output dac, and that is a really easy and highly practical way to get a bridge amp for big lively realistic dynamic punch. Perhaps an overdo, but not boring.
