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View Poll Results: Would you like a valve based DAC?
Yes, with multiple inputs. 29 60.42%
Yes, with only one input 16 33.33%
No 3 6.25%
Voters: 48. You may not vote on this poll

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  #1  
Old 8th December 2007, 11:36 PM
tomtidswell tomtidswell is offline
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Default Valve based Digital Analogue Converter

How about it?

I have 4 optical output sources, an iRiver (nonApple mp3 player), a CD player, a DVD player and an Apple Laptop. Having a valve based optical digital to analogue converter would be ideal (and even save on an upgrade of the CD player).

Tomtidswell
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  #2  
Old 8th December 2007, 11:45 PM
pre65's Avatar
pre65 pre65 is offline
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Default Re: Valve based Digital Analogue Converter

Hi-what about a valve buffer and DAC ? (as 2 separate components)

It has been said a valve buffer can give a CD player a more "analogue" sound and even improve the "drive" of a passive pre.


Philip
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Philip.

Everything in this post is my honest opinion based on what i thought I knew at that very moment in time.

Last edited by pre65; 9th December 2007 at 12:10 AM.
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  #3  
Old 11th December 2007, 05:25 PM
NickW NickW is offline
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Default Re: Valve based Digital Analogue Converter

Quote:
Originally Posted by pre65 View Post
Hi-what about a valve buffer and DAC ? (as 2 separate components)

It has been said a valve buffer can give a CD player a more "analogue" sound and even improve the "drive" of a passive pre.


Philip
Hi Philip,

I've heard the same but surely all the added valve buffer can do is "alter" or mask what is going into it (?). I started to build my own DAC with valve output stage some time ago, but got hoplessly diverted in building the WD88 and Pre3/Phono3 etc, etc. However, that phase is coming to an end, and I'm looking to resurrect the DAC project.

I had baselined the Burr Brown PCM1704, being the last word in parallel multibit DAC technology. I got as far as getting the basic DAC functioning, but not the valve output stage. Since then, up-sampling techniques seem to have come along with some favourable reviews. The hybrid BB PCM1794 DAC also seems to have been widely accepted. The next challenge is then to have a properly integrated valve output stage in place of the traditional op-amps.

The point of this reply is that I would agree that a DAC kit would be really good to have, but "specing" it might be quite challenging. Some will want no oversampling, others will want bells and whistles.

Nick
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  #4  
Old 12th December 2007, 02:33 PM
robinhelen robinhelen is offline
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Default Re: Valve based Digital Analogue Converter

Hi,
Why have an output stage???
I use a TDA1543 NOS DAC using 12 stacked chips. This provides plenty of output using passive I/V i.e. 2 resistors. This is connected straight to my amp input with no coupling capacitor (as the amp input uses one). I originally thought about a valve buffer, and with just 1 chip it would be necessary I think, but 12 chips does the trick perfectly. Virtually nothing in the signal path, no oversampling, no filtering = very good sound it seems. The DAC came as a modular kit and you can have as many multiples of 12 chips as you like. The more chips the greater the effective bitrate achieved.
Rob
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  #5  
Old 12th December 2007, 05:12 PM
Dik Dolan Dik Dolan is offline
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Default Re: Valve based Digital Analogue Converter

Why use chips.... how about a fully valve dac? How hard could it be?=)





*That just proves my ignorance*
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  #6  
Old 4th January 2008, 11:06 AM
david beard david beard is offline
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Thumbs up Re: Valve based Digital Analogue Converter

I'd be interested for sure!

didn't HFW do avalve DAC years back - I seem to remember something along such lines - does anyone else remember this and better still have any details of what it was all about?

Cheers
Dave
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  #7  
Old 1st February 2008, 12:39 PM
little eddy little eddy is offline
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Default Re: Valve based Digital Analogue Converter

I'm all for this. My AN DAC kit has always bettered any intergrated valve output CD player that I have tried in the past, (although I have not tried any of the newer entrants). The power supply, descrete component and valve options available together with an appropriate DAC that a new kit could consider and offer, should prove to be a very impressive performing unit.

What about including an AES/EBU input given the increasing number of US equipment supporting balanced digital outputs? Even my old modest Cambridge Audio DiscMagic transport has a balanced output and from the listening tests I did, this was preferred to the unbalanced RCA output, (possible because my AN DAC has switchable RCA and XLR inputs).

Although not of interest to me, AN DAC kit also has a USB input option.
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  #8  
Old 2nd February 2008, 09:13 AM
Black Stuart Black Stuart is offline
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Default Re: Valve based Digital Analogue Converter

Robinhelen,
have you had a look at NOS DAC thread on diyaudio, fascinating and that Dutchman takes on board all suggestions. The intensity of investigating all possibilities is mind blowing. BTW he also sells a PCB which is supposed to be top class.
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  #9  
Old 11th February 2008, 03:38 PM
Tourmaline Tourmaline is offline
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Default Re: Valve based Digital Analogue Converter

Quote:
Originally Posted by Black Stuart View Post
Robinhelen,
have you had a look at NOS DAC thread on diyaudio, fascinating and that Dutchman takes on board all suggestions. The intensity of investigating all possibilities is mind blowing. BTW he also sells a PCB which is supposed to be top class.
I heard the audio note NOS dacs in action; no harshness whatsoever and very lifelike, touchable sound. Now is that a trade mark of audio note but i can imagine that most NOS dacs share that common feature...

I also read that alot of people comming from multi sampling dacs/oversamplings dacs cannot go back once they took the step to go NOS.
The other side i hear is that NOS dacs might not as detailed as the oversampling/multi sampling dacs.

In the end, it's all about preference and taste.
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  #10  
Old 11th February 2008, 08:19 PM
NickW NickW is offline
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Wink Re: Valve based Digital Analogue Converter

Hi all,

Just to add to the debate....I recently ordered a RAKK DAC-2 with passive output board. It uses the BB PCM1794 DAC with asynchronous upsampling - the modern school I believe? - and the opposite end of the spectrum to the NOS DACs with zero upsampling/reclocking (?).

I have to say it blows my old Meridian 606 DAC out of the water!, and I had thought that the 606 (coupled with the 602 transport) was pretty good. I'm told an active valve output stage will make things even better, but I can't stretch that far yet. However, all in all, the passive output RAKK DAC-2 has more "music", detail, etc than anything other than the best CD player I've heard to date which was/is the Krell Evolution 505 at ~ £9k at Oxford Audio Consultants in the the process of buying near speakers.

The RAKK DAC-2 has so far cost me ~ £350 (the current US Dollar rate really helps), and I'm chuffed to bits with it. It works really well with the Meridian 602 transport, but I suspect any other transports would be ok too due to the asynchronous upsampling.

Ok, I shall now keep my head down amidst the barrage of offended Forum readers that truly believe the NOS side is best.....

NickW
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