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#81
Posted to rec.audio.tubes
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Tube DACs??
Patrick Turner wrote:
Nick Gorham wrote: TT wrote: "flipper" wrote in message ... On Tue, 2 Dec 2008 13:26:05 +0900, "TT" wrote: "flipper" wrote in message om... Actually, other than Andy's style being perhaps more clever than yours, the only thing a "rational observer" could draw from it is that neither of you likes each other very much. The fact is, no one likes Arny very much at all anywhere ;-) BTW Arny is also a compulsive liar. Cheers TT I was going to question the validity of those claims but Arny is making your case for you. I failed to mention his sanity level is variable but you have already figured that out by now :-) Cheers TT Actually, A tube DAC would be easy, use a FPGA to convert from PCM to delta sigma (still digital), use that to drive a pentode with a low pass filter on its output, and there you are, the D to A is done by a tube. (ducks and runs) We might run right after you and blast your arse with buckshot. Talk about easier said than done. Where's your schematic for such a scheme? Patrick Turner. -- Nick Well if you will allow me to draw the FPGA as a black box then should be simple enough :-) You would run out of frequency response with a simple CD resolution, might manage a 8bit converter though. PCM - PCM to DSigma Converter - Glowing low pass filter -- Nick |
#82
Posted to rec.audio.tubes
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Tube DACs??
In article ,
Nick Gorham wrote: TT wrote: "flipper" wrote in message ... On Tue, 2 Dec 2008 13:26:05 +0900, "TT" wrote: "flipper" wrote in message ... Actually, other than Andy's style being perhaps more clever than yours, the only thing a "rational observer" could draw from it is that neither of you likes each other very much. The fact is, no one likes Arny very much at all anywhere ;-) BTW Arny is also a compulsive liar. Cheers TT I was going to question the validity of those claims but Arny is making your case for you. I failed to mention his sanity level is variable but you have already figured that out by now :-) Cheers TT Actually, A tube DAC would be easy, use a FPGA to convert from PCM to delta sigma (still digital), use that to drive a pentode with a low pass filter on its output, and there you are, the D to A is done by a tube. (ducks and runs) That was one of the three tube DAC techniques that I mentioned I was thinking of in my earlier post. Each method had a potential problem. The potential problem with this one is that it has been too long since I was involved in these things and I couldn't remember how to calculate what rate the one bit pentode DAC would have to run at in a third order delta sigma converter system to equal CD resolution. IIRC a first order delta sigma would have to run at about 3 GHz, probably a little fast for a pentode, to equal CD resolution but IIRC a third order delta sigma brings that down into the realm of possibility. Anyone know the actual number? -- Regards, John Byrns Surf my web pages at, http://fmamradios.com/ |
#83
Posted to rec.audio.tubes
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Tube DACs??
Andy Evans wrote:
I'm a university lecturer I have an exceptionally low opinion of those and that was at UCL. Graham At UCL in what capacity - lecturing or learning? Or neither? andy |
#84
Posted to rec.audio.tubes
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Tube DACs??
John Byrns wrote: IIRC a first order delta sigma would have to run at about 3 GHz, probably a little fast for a pentode No conventional tube can run that fast. Haven't you studied the subject ? Graham |
#85
Posted to rec.audio.tubes
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Tube DACs??
Andy Evans wrote: Andy Evans wrote: I'm a university lecturer I have an exceptionally low opinion of those and that was at UCL. At UCL in what capacity - lecturing or learning? Or neither? As a 1st year undergraduate. I knew more about real world electronics than the lecturers did. They were living in that fantasy world often called an 'ivory tower'. Graham |
#86
Posted to rec.audio.tubes
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Tube DACs??
flipper wrote:
On Wed, 03 Dec 2008 10:25:39 -0600, John Byrns wrote: In article , Nick Gorham wrote: TT wrote: "flipper" wrote in message m... On Tue, 2 Dec 2008 13:26:05 +0900, "TT" wrote: "flipper" wrote in message news:vft8j49gopmetv2515hq5ki6tf90fu1om9@4ax. com... Actually, other than Andy's style being perhaps more clever than yours, the only thing a "rational observer" could draw from it is that neither of you likes each other very much. The fact is, no one likes Arny very much at all anywhere ;-) BTW Arny is also a compulsive liar. Cheers TT I was going to question the validity of those claims but Arny is making your case for you. I failed to mention his sanity level is variable but you have already figured that out by now :-) Cheers TT Actually, A tube DAC would be easy, use a FPGA to convert from PCM to delta sigma (still digital), use that to drive a pentode with a low pass filter on its output, and there you are, the D to A is done by a tube. (ducks and runs) That was one of the three tube DAC techniques that I mentioned I was thinking of in my earlier post. Each method had a potential problem. The potential problem with this one is that it has been too long since I was involved in these things and I couldn't remember how to calculate what rate the one bit pentode DAC would have to run at in a third order delta sigma converter system to equal CD resolution. IIRC a first order delta sigma would have to run at about 3 GHz, probably a little fast for a pentode, to equal CD resolution but IIRC a third order delta sigma brings that down into the realm of possibility. Anyone know the actual number? I don't think it matters because, if I understood his brief description, the 'tube' would be simply the last stage filter and you don't want the filter 'responding' at the bit rate anyway... or else it isn't 'filtering'. Yep, the tube would form part of the low pass filter. I am forcing myself to read some docs though (it was only a off hand comment), I don't think it would need to. Looking at DSD 2.8MhZ will be enough, well within a pentodes area, and many triodes for that matter. -- Nick |
#87
Posted to rec.audio.tubes
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Tube DACs??
Patrick Turner wrote in
: LGLA wrote: "cipher" wrote in message 0... These seem to be popping up everywhere in audiophile circles.. what would be the purpose of such a device? Yes, I am young and ignorant re electronics. something about the whole thing seems counter intuitive to me. One thing I have noticed about stereo stacks... everything has an output in one way or another, even if it is the sound itself, from a speaker. And, the output stage of a DAC would be the point, just for that tube's worth of sound quality. Any output stage to another component, is an amplifier. This is my FIRST post, as a reply, in this NG. Alex SoCalifornia Welcome to our little group. I hope you have a wardrobe full of flame suits to protect yourself from the barbs, sarcasms, inuendo, and downright BS that this group generates like mushrooms springing up in compost. Between the lines of BS there is much to be treasured here, and if you increase the treasure then you'll get by better than some. If you did all the functions of a D to A converters using tubes, methinks you'd have no room to keep a wife at your house and you'd be horrified by the power bills. The Green Police would call to arrest you for causing so much greenhouse gas. Rather a lot of tubes are needed. However, their purpose would be to perform un-digitalling tasks which can be done better with zillions of transistors in a chip. But the tubes are very nice things to use as the fist device to handle and filter the audio coming from the DA chip. But soon the digital world will be rocked with DXD etc, so prepare to say tata to CDs. The world has always hosted a mix of the best and the worst in any product. MP3 is the worst, but the DXD could be the best but only for those who can afford it unless the DXD becomes a real cheap alternative due to parallel developments in data processing speeds, memory capacities and broadband data transfer rates. Put it this way, in 25 years time, will anyone remember how CD players worked? Will replacement lasers be available? Will anyone know how to install them? And won't 44kHz x 16 bit all seem even more primitive than vinyl? And will we have holographic porno online streaming? and film character / plot choice? and a host of other gee wizz ways of creating entertainment without actors, actresses, and orchestras? Hu nose? I don't. And the future might arrive and I'll be too old to enjoy it. Patrick Turner. There are several benefits to DXD(24 bit word @ 352,8 kHz sample rate) as a recording and editing medium(such as the allowance for a relaxed ADC anti-aliasing roll-off filter)but, I do not think it will make a big splash, personally...a couple of companies use it(Telarc and Lyndberg Lyd labels are a couple), but the software/hardware required is too expensive and propreitary..... it is a small niche format for small niche companies. im guessing it wont do any better than DSD..) tape and 24/96 etc will reign supreme for a very long time. |
#88
Posted to rec.audio.tubes
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Tube DACs??
Eeyore wrote in
: http://www.museumofhoaxes.com/hoax sir, those aint nothin... http://www.machinadynamica.com/machina60.htm http://www.machinadynamica.com/machina31.htm http://www.belt.demon.co.uk/product/bpaip.html |
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