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Old 26th February 2009, 01:48 PM   #1
atcgreg is offline atcgreg  Luxembourg
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Thumbs up NON-OS DAC 8xTDA1543

Hi
I would like to share my experience with the mods I did on the Chinnes made LITE DAC-AH. Got it on ebay for less than $70 bucks with shipping(lucky buy). Fitted in a nice metal box the DAC-AH sounded a little flat harsh and undynamic from new, only to improve over the space of a month. The worst in this respect was still the smeared sound stage less detailed sound. So I ripped it apart to see what could be done. Not much space to make radical make over so I concentrated on the power supply and buffer this seems to be always the weakest link. I had no schematics but it turned out to be almost 100% clone of TNT Convertus DAC NOS it differs that TNT uses 4 TDA1543 and LC filter buffer. The Chinnes dac has OPAMP stage with OPA627BP it is a good opamp but the sound was just not good a bit harsh at top and dull bass . So simple solution I replaced it with favorite opamp LME48720 it is the single version of LME49720 ( dual opamp).
The dynamics are the first thing to strike you, then the greater space between the instruments and the increased level of detail. All this by just replacing the OPAMP!!!
Next the supply it had 3 elcheapo rectifier brigdes (noname)so took them out one was for digital (dac 5V) others for the"analog" side(-/+12v) Replaced by BYV27-100 ultrafast diodes. Also it is very crucial to change the I/V resisters to good low noise like VISHAY or Caddock . Now the sound got more concentrated focused with even greater details.
The caps were increased to 2x4700uf/16 with a bypass of 0.47uf/100v WIMA. I can enjoy music with pure delight. I am thinking of putting it in a bigger box with complete makeover bigger toroide trafo and better power supply with shunt regs.etc

My friend got the same DAC and funny enough his had AD847JN at the buffer stage it gave good sound but compared to mine with LME49720 is like night to day. There are companys (USA) that resell the DAC with modifications like without the buffer stage just a coupling transformer and other mods but the price is $1.200 usd WOW . I did mine for 200usd. I do not know if i have achieved the same result but I am sure it was worth it and I
enjoy music.When I'll finish doing the digital output of my CDP302ES this dac will be the first to be hooked up to it.
GREG

PS I also found this dac with an tube output mod. Mr.Fikus that made it claims it the sound is great as well. might check it out and do it someday.
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Old 6th April 2009, 10:06 AM   #2
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hi, thanks for sharing the useful dac ah mod. do u have any ideas about modifying the output stage to tube stage? I went to Fikus's website but i cant udnerstand as im still a DIY amateur. Any ideas where i can find step-by-step guides to build a, lets say, cathode follower tube output stage? Thanks.
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Old 6th April 2009, 01:11 PM   #3
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so your parallel TDA nos dac sounds best with the slowest slew rate opamp, yeah what a great mod indeed it even worths a topic
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Old 28th April 2009, 08:15 AM   #4
atcgreg is offline atcgreg  Luxembourg
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Exclamation Slew rate????

Quote:
Originally posted by tritosine
so your parallel TDA nos dac sounds best with the slowest slew rate opamp, yeah what a great mod indeed it even worths a topic
Slew rate helps to identify what is the maximum input frequency applicable to the opamp such that the output is not distorted. Thus it becomes imperative to check the datasheet for the device's slew rate before using it for high frequency applications.

that's a reminder to you what does "slew rate" mean.

Well I do not know where did you get your technical info about LME49720 but you are wrong it is one of the BEST op amp and made to work in such designs as the output buffer with open loop gain / high freq and not only. Campare it to OPA ones or even the AD ones

And don't knock it if you have not herd it. I know that the best solution would be to get the opamps out and use 1uF PIO direct from the TDA1543 outputs to the sockets but the ones i have won't fit because of size. So it had to be a compromise to a good opamp.

So maybe next time give a worthy reply and check your source

:
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Old 28th April 2009, 08:25 AM   #5
atcgreg is offline atcgreg  Luxembourg
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Quote:
Originally posted by kennykong
hi, thanks for sharing the useful dac ah mod. do u have any ideas about modifying the output stage to tube stage? I went to Fikus's website but i cant udnerstand as im still a DIY amateur. Any ideas where i can find step-by-step guides to build a, lets say, cathode follower tube output stage? Thanks.

Hi
i think that LAMPIZATOR does give a step by step DIY tube ouput please check his site again or click on this tube output

or thistube output in pics

If this does not help email me and i will try to make a tutorial for you.

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Old 28th April 2009, 08:58 AM   #6
DUC985 is offline DUC985  Germany
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i do not get why this Finkus guy is doing all this SRPP tube output stages no matter what DAC is used at the input.
This makes no sense at all if you use 8XTDA1543. They have enough power without an active I/V. For what would you need 20 Volts at the output ???

Check the webside of DDDAC what can be done with paralleled 1543 chips.
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Old 28th April 2009, 09:09 AM   #7
atcgreg is offline atcgreg  Luxembourg
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Exclamation Tube output

Quote:
Originally posted by DUC985
i do not get why this Finkus guy is doing all this SRPP tube output stages no matter what DAC is used at the input.
This makes no sense at all if you use 8XTDA1543. They have enough power without an active I/V. For what would you need 20 Volts at the output ???

Check the webside of DDDAC what can be done with paralleled 1543 chips.

Yes I agree to that above this Fikus method is wierd

But if someone wants a tubed version then it could be lowered to the 2V but like you say the TDA1543 is powerful enough without need the opamps or tubed.

maybe he's deaf needs extra power to hear!!! just joking no offence meant.
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Old 28th April 2009, 09:34 AM   #8
atcgreg is offline atcgreg  Luxembourg
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Default LME49710 used in TDA1543 nos DAC

Hi I came across this upgrade of the circiut with the opamp
to lower the DC voltage at the output of opamp LM4562 aka LME49710 in the NOS DAC.
click on the link . upgrade of opamp in NOS dac

I did not measure my dac's output but I will post a message after i wil check this out. I know that there was a thread on the forum about DC voltage on the outputs of poweramps but it is the same issue with opamps. Guess we tend to forget about. that.

enjoy the music
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Old 28th April 2009, 05:27 PM   #9
Zoran is offline Zoran  Serbia
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peolpe,
I have respect to every diy-er
BUT
the lampizator is wrong design...
*
see what value of output signal You will have
applyaing that circuits...
about 20V, or more
to totally overload preamps
or keep the, usualy crappy pot, at close to zero...
*
If You want decent tube out from dac
use 6SN7 at high voltage in plain anode mode config.
or JFET...
not high transconductance tube in srpp, with high gain
just because it is easy to implement for low Vb...
*
please...
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Old 11th May 2009, 07:41 PM   #10
Tolu is offline Tolu  Germany
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Hi atcgreg,

could you please post the circuit of your output stage?
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