SHEK DAC lampy mods ?

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pre65
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#1 SHEK DAC lampy mods ?

Post by pre65 »

My first DAC was a Shek non o/s TDA1543 model. Since DAC number two (in a WD series 3 case) is in the main system I thought the Shek might be ripe for Lampy mods, inspired by Richards latest project.

The Shek has a CS8412-cs digital audio interface reciever and a Phillips 74HC4040n 12 stage binary ripple counter.

From what I have read, the Lampy stage is taken from the resistors after the DAC chip. On the Shek there seems to be a 2K7 resistor for each channel after the chip, so is the feed taken before, or after the resistor ?

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Nick
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#2

Post by Nick »

Depends where the resistor is, I would expect its the I/V resistor after the dac, so the other side of the resistor will be ground.
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pre65
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#3

Post by pre65 »

This is a close up of what I think is the DAC output.

Shows two resistors and two caps + a variable resistor.

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#4

Post by Nick »

Ok, and?
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#5

Post by pre65 »

Nick wrote:Ok, and?
I was hoping to find where to take the DAC output from for the Lampy output stage.

Looking at the first picture there does not seem to be an op-amp on the output ?
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#6

Post by Nick »

Resistance isn't futile it's V / I.
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pre65
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#7

Post by pre65 »

Aha, thanks for that Nick, I should have thought of that myself. :oops:

Seems in my ignorance I was right, those 2K7R resistors are on pins AOR and AOL which is the output.

Another thing, I did not know that TDA1543 was an "economy" DAC chip.

So now I know where to take the signal out. Magic. :D
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#8

Post by pre65 »

After reading about Richards noble efforts I have decided to have a go on a valve output stage on my Shek DAC which has the TDA1543 chip.

I too, was looking at the Thorsten circuit, and for stage one will give that a go.

One thing I'm not sure about, is where to take the DAC output from, is it straight from the DAC, before the (in this case) 2K7 resistor ?

Another thing, these 6n2p valves, are the cheapie Russian ones OK or are there better ?
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#9

Post by pre65 »

Sort of progress.

I've ordered 4 6n2p valves.

I found this article about a DIY DAC using the TD1543 chip, and was interested to see how they have coped with the falling output above 20K hz by a parallel resonant circuit.

So, one of them into Richards version of the 6n2p output stage and whizzo, we have a plan. :wink:

http://www.diyparadise.com/rm20dac.html

If this works I can be a bit more bold and try modding the Honkers DAC in the main system.
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#10

Post by al newall »

pre65 wrote:
Another thing, these 6n2p valves, are the cheapie Russian ones OK or are there better ?
They should be ok, unless there are any with the EV suffix available.
6n6p-EV and 6n1p-EV are supposedly more desirable than the standard tubes, but i can't hear any audible difference.
Much to learn there is.
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#11

Post by pre65 »

al newall wrote:
pre65 wrote:
Another thing, these 6n2p valves, are the cheapie Russian ones OK or are there better ?
They should be ok, unless there are any with the EV suffix available.
6n6p-EV and 6n1p-EV are supposedly more desirable than the standard tubes, but i can't hear any audible difference.
The 4 I ordered are 6n2p EV. :wink:
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#12

Post by al newall »

The 4 I ordered are 6n2p EV.
Jolly good.
May as well start off with the best.
Might have a look at 6n2p myself, while the prices are low.
They might get popular like 6n6p did.
Much to learn there is.
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