As far as I can see he's not calling anyone a poopy head, he's simply using that phrase as an example of what NOT to respond to.
Talk of libel is just silly IMO
What bothers me more is after reading this whole thread, my knowledge of DAC's (with or without a valve stage) has not advanced one millimetre.
Talk of libel is just silly IMO
What bothers me more is after reading this whole thread, my knowledge of DAC's (with or without a valve stage) has not advanced one millimetre.
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Just a Joke
Absolutely. It was my poor attempt at humorous sarcasm, with allusion to a previous post.
Absolutely. It was my poor attempt at humorous sarcasm, with allusion to a previous post.
I don't remember using the phrase, but I am guilty of thinking it.
Now as I am too simple to recognise a Valve IV stage...
The connection shown from the Digital board to the Valves is a single wire, now an IV stage as far as I know does:
So while you may think I am simple/daft/etc my questions were aimed at this concern but where totally ignored and not picked up by yourself or others. Now I don't know whether you understand how signals actually travel, but you cannot send signals that have not been low pass filtered to remove the very high frequency content down a single wire without the return wire in close proximity, otherwise you will get serious noise problems and signal integrity issues. Hence my questions regarding the function of the valves.
I bow to your greater knowledge having read your posts of the last year or so.
Now as I am too simple to recognise a Valve IV stage...
The connection shown from the Digital board to the Valves is a single wire, now an IV stage as far as I know does:
Now until this is filtered this line will have an ac content, carrying it by one wire and having the return signal follow the torturous path through the star ground is not the best option for noise free operation. You may want to look up some of the interesting stuff on loop areas.
So while you may think I am simple/daft/etc my questions were aimed at this concern but where totally ignored and not picked up by yourself or others. Now I don't know whether you understand how signals actually travel, but you cannot send signals that have not been low pass filtered to remove the very high frequency content down a single wire without the return wire in close proximity, otherwise you will get serious noise problems and signal integrity issues. Hence my questions regarding the function of the valves.
I bow to your greater knowledge having read your posts of the last year or so.
Any signal with almost square edges has a large content of high frequency harmonics, these need the return path to be in close proximity otherwise you are creating large loop areas (and coupling the noise to anything within the loop)and extra noise on the ground due to the return signal having to travel the torturous route, this is basic EMC and signal integrity, and avoiding this is standard practice in electronics.
Have I done the experiment, yes, I have seen it on various jobs I have worked on over the years where this has happened inadvertently, but even without doing the experiment you can draw out the loops created and see these are not good. This high frequency content follows the path of least inductance and so need a return in close proximity (preferably twisted) to provide this return.
Plenty of info on sites such as Henry Ott, Howard Johnson etc regarding such problems.
Have I done the experiment, yes, I have seen it on various jobs I have worked on over the years where this has happened inadvertently, but even without doing the experiment you can draw out the loops created and see these are not good. This high frequency content follows the path of least inductance and so need a return in close proximity (preferably twisted) to provide this return.
Plenty of info on sites such as Henry Ott, Howard Johnson etc regarding such problems.
Would you be willing to share some of the experimental details here? For example the rise time and rough amplitude of the signal, the loop area and how great the noise you encountered was in a specified bandwidth?
Questions are sometimes asked rhetorically, or because the questioner suspects that the other party involved has not asked the question of himself. There is no question in audio electronics which is so basic that it cannot be given the wrong answer by someone, including people who make their living from audio.Ryelands said:
I don't have to prove anything about anything. I just comment. People comment back. That is what happens on a forum. I have never claimed any great psychological insight; I thought you were doing that. It may be true that group Y likes device X because of its distortion. To demonstrate that this is a plausible proposition all that is needed is to show that some in group Y specifically ask for a device with distortion of a particular form (e.g. see this recent thread), and that device X probably delivers this form of distortion. If you demand proof of all statements made then perhaps HydrogenAudio might be a better forum for you.
Unnecessary. You would complain bitterly if I treated you so discourteously.
Details
Moving along, does anyone know or have any reasonable idea what dac chip and USB interface is being used in these dacs? The website says, " It is a genuine original design, based on chips previously not used together and in a configuration un- tried before . The chips are current production, latest models and not nostalgic 16 bit units. It is a multi bit top model with fully differential balanced outputs and 192 kHz capability." There is no further information or schematics posted, quite unlike Broskie and Pass.
Moving along, does anyone know or have any reasonable idea what dac chip and USB interface is being used in these dacs? The website says, " It is a genuine original design, based on chips previously not used together and in a configuration un- tried before . The chips are current production, latest models and not nostalgic 16 bit units. It is a multi bit top model with fully differential balanced outputs and 192 kHz capability." There is no further information or schematics posted, quite unlike Broskie and Pass.
I'm a big fan of multibit DAC chips but I've never come across one with a differential output other than the ones designed for communications applications, not audio. Those have the capability to go way beyond 192kHz though. They only go up to 16bits as far as I'm aware - most of them are 14bits or less.
http://www.analog.com/static/imported-files/data_sheets/AD1955.pdf
http://www.wolfsonmicro.com/products/dacs/WM8741/
If referring to R2R multi-bit your statement is probably true, but you did not preface the comment with that distinction so I am not exactly sure what you meant.
Texas instruments has a whole slew of audio dacs they label sampling advanced segment dacs with differential current or voltage outputs depending on device.
Granted, people don't generally post that they find some postings in a thread to be over the top and in poor taste. But I believe that it's allowed to do so.
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I saw some of these chips when I searched. However, the website asserts, "..chips previously not used together and in a configuration un- tried before . The chips are current production, latest models...". Maybe he is using several or more of one of these chips, together with other chips? It would be interesting to know more detail.
The parts you cited I term 'sigma-delta'. Whilst its true they have multibit modulators, I've never seen them referred to as 'multibit dacs' before. I was not only referring to R2R - that's a subset of multibit.
Those are also sigma-delta.
@marce - how about the details from the experiment you did? I'm eager to learn!
As soon as I get time I will provide as much detail as I can.
It was not an experiment as such though it ended up as one, it was an overdesigned auxiliary input, that you could say went a bit wrong. Basically to provide isolation the engineer decided to digitise the input transmit it as digital through a custom planar transformer (capacitavly screened) to provide isolation. This was then converted back and transmitted further as PCM (I will have to check details). Because of the crazy grounding scheme to combat noise and use of connectors to connect the isolated audio board, the return for this signal had to travel all the way round the ground connections through the PSU and back via the isolated audio to the source. This ended up with a nice 4-8Khz hiss. This was in a vey compact unit with numerous processors and analogue sections with op-amps and gain stages (120mmx120mmx70mm volume, 4 PCB's) so it was more extreme than in a commercial unit withy things spread out more.
I will draw out the diagram later, but was similar to the ground loops shown on JNeutrons page.
My 3 month old second hand car disintegrated a bit yesterday, and the company I bought it of is disputing the 4 month guarantee I paid for!!
It was not an experiment as such though it ended up as one, it was an overdesigned auxiliary input, that you could say went a bit wrong. Basically to provide isolation the engineer decided to digitise the input transmit it as digital through a custom planar transformer (capacitavly screened) to provide isolation. This was then converted back and transmitted further as PCM (I will have to check details). Because of the crazy grounding scheme to combat noise and use of connectors to connect the isolated audio board, the return for this signal had to travel all the way round the ground connections through the PSU and back via the isolated audio to the source. This ended up with a nice 4-8Khz hiss. This was in a vey compact unit with numerous processors and analogue sections with op-amps and gain stages (120mmx120mmx70mm volume, 4 PCB's) so it was more extreme than in a commercial unit withy things spread out more.
I will draw out the diagram later, but was similar to the ground loops shown on JNeutrons page.
My 3 month old second hand car disintegrated a bit yesterday, and the company I bought it of is disputing the 4 month guarantee I paid for!!
HELP ! I can't find the DAC inside my Technics SL PG 440A
It has a MASH MN6474 dac. But the PCB is very different than other Technics.
Here is my SL PG 440A open. As you can see , there isn't any square in the PCB where you could spot the DAC unbeneath it.
In comparison , here is the SL-PS700 which Lukasz Fikus lampizated
You can easily spot 3 squares in the PCB where the dac , digital filter with demodulator , and other chip are located. And if you flip the PCB , you can see the DAC indeed.
Could it be the case that the Mash DAC is located in the front panel control PCB?
It has a MASH MN6474 dac. But the PCB is very different than other Technics.
Here is my SL PG 440A open. As you can see , there isn't any square in the PCB where you could spot the DAC unbeneath it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
In comparison , here is the SL-PS700 which Lukasz Fikus lampizated
You can easily spot 3 squares in the PCB where the dac , digital filter with demodulator , and other chip are located. And if you flip the PCB , you can see the DAC indeed.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Could it be the case that the Mash DAC is located in the front panel control PCB?
cost + hype is blinding people
I have heard the level 5 dac and it is nice, unfortunately it was through the vac statement 450 (pair with statement line pre and perfect8 tech the force speakers I liked the dac but need to here it on a accurate system as that over priced work of art sounds fake as hell.The force has no realism in the reproduction of any mid-band power. They remind me of a mega line.
I have heard the level 5 dac and it is nice, unfortunately it was through the vac statement 450 (pair with statement line pre and perfect8 tech the force speakers I liked the dac but need to here it on a accurate system as that over priced work of art sounds fake as hell.The force has no realism in the reproduction of any mid-band power. They remind me of a mega line.
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