Looking for an active I/V stage for TDA1543-based DAC - diyAudio
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Old 14th June 2004, 04:38 PM   #1
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Default Looking for an active I/V stage for TDA1543-based DAC

Could someone recommend a high-end active i/v stage for TDA1543 using opamp or transistors? It has to be suitable for portable setups.

I found quite a few of them, but most use +-18V which is a bit too much. Something based on AD8620 or OPA627 would be ideal, i think.

Many thanks!
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Old 14th June 2004, 09:49 PM   #2
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Default Re: Looking for an active I/V stage for TDA1543-based DAC

Quote:
Originally posted by IpsilonSound
Could someone recommend a high-end active i/v stage for TDA1543 using opamp or transistors? It has to be suitable for portable setups.

I found quite a few of them, but most use +-18V which is a bit too much. Something based on AD8620 or OPA627 would be ideal, i think.

Many thanks!
Just see the datasheet of the TDA1543 and use a +/- 5V opamp.
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Old 14th June 2004, 11:05 PM   #3
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Default Re: Re: Looking for an active I/V stage for TDA1543-based DAC

Quote:
Originally posted by Elso Kwak


Just see the datasheet of the TDA1543 and use a +/- 5V opamp.
Ok, I'll be more specific....
The I/V section from the datasheet is very simple and uses a generic opamp. I'm sure that after spending a couple of weeks I'll develop something better. What I am looking for is a quality solution to start with and tweak too, something with a Class-A biasing, virtual ground, quality caps for bypassing and so on.

I searched on the forum and came up with this schematics, going to try it out soon and post the results:
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File Type: jpg ivstage.jpg (31.0 KB, 608 views)
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Old 14th June 2004, 11:08 PM   #4
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Smile Re: Re: Re: Looking for an active I/V stage for TDA1543-based DAC

Quote:
Originally posted by IpsilonSound


I'm sure that after spending a couple of weeks I'll develop something better.
IpsilonSound,
I am looking forward to it!
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Old 14th June 2004, 11:32 PM   #5
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Hi IpsilonSound
How are finding your dac thus far?
Did you connect it up to your amp successfully? [single supply]

I shall be interested in your ongoing active IV quest, been considering investigating something active myself.
Though space and power supply are also at a premium in my
application.

Cheers

Setmenu
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Old 14th June 2004, 11:56 PM   #6
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Check this thread: Tda1543=>opa2604
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Old 15th June 2004, 03:30 AM   #7
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Quote:
Originally posted by Peter Daniel
Check this thread: Tda1543=>opa2604
Thanks, Peter... I've seen the thread already and considered the chip for I/V conversion. The THD is just .0003%, it's unity gain stable and needs only one power supply which will facilitate biasing to ClassA. The OPA2604 would be a nice dual chip for this task, I'll order a couple of samples of them to try them out with my DAC.
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Old 15th June 2004, 03:43 AM   #8
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Quote:
Originally posted by setmenu
Hi IpsilonSound
How are finding your dac thus far?
Did you connect it up to your amp successfully? [single supply]

I shall be interested in your ongoing active IV quest, been considering investigating something active myself.
Though space and power supply are also at a premium in my
application.

Cheers

Setmenu
Hi Setmenu,

I haven't managed to solve this issue so far 100%. Omitting the ground or putting the bypass cap between the ground and the pot solves the single power supply issue for DAC and PPA. But the sound is not up to what I could live with. It's affected, not as smooth and dynamic. Using transformers will fix the problem and , but transformers are too large to be put inside the PPA case.
I guess, the only option would be active stage with opamps.
I would hate to reject the idea of PPA+DAC under a single case, the PPA is already large to be called 'portable'.
By the way, you got real talent to put so much into such a tiny case.
Cheers!
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Old 15th June 2004, 05:41 AM   #9
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I've seen some recommendations about THS4062 and THS4082 chips to be used for DAC. Anyone could share experiences with them?
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Old 15th June 2004, 12:03 PM   #10
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Hi IpsilonSound
I too found the shared battery less than satisfactory.
That said the added weight /bulk of duel packs is not too bad,
about 60 grams extra depending on capacity,I tend to allow for
about 10hours run time as a minimum.
The whole setup weighs in at about 570 grams + bag.
My previous outboard dac setup was more like 1000gram +bag
Mind all the above is insane compared to an Ipod + buds ,hehe.

So your is setup is intended as the above, for portable use?
If so, I am presuming you mean more for transportable rather
than something to be carried about when going for a walk!

So how is it all sounding thus far?
Do you like the sound of the passive dac?

I am pretty happy with mine , it is certainly is not perfect! But it has been pressed into service .
It also chucks out a fair bit of heat especially boxed up and inside a soft bag during warm weather..[1543 running at 8v]

It would be interesting to built something else , say delta sigma
based , [CS 43122?] but I have not done much studying of these
dacs as yet.
It would still have to fit into a tiny space , and I have a feeling
that things could be more 'tetchy' with this technology?

But at the moment being steeped in ignorance [compared to folk here!!] I am just pleased to have hit my target and completed a
project that is now actually being used


Cheers

Setmenu
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