Using the AD844 as an I/V

[georgehifi]

Here is one measurement of AD844 used in I/V:

AD811
THD(+N) at 0dBFS is much higher than in OPA1611

Then a "tripple stack" of 844's "should" be better than the opa1611?, and done without the need of feedback?

Cheers George

​

 

[bohrok2610]

Your quote is not altogether correct as that text refers to AD844, not AD811.

Parallel AD844s should have lower noise, but THD improvement is doubtful although lower input impedance may help. Costwise hard to see the point especially compared to the discrete BJT IV.

 

[tonimxp]

It looks fine, good luck with your TDA1541 implementation!

Hmmm....should I be worried?

 

[batteryman]

I have eight unused 844s if anyone wants them for a small fee. I went down the Sowter I/V transformee route for my dual 1541 dac,

 

[abraxalito]

Hmmm....should I be worried?

Are you worried about becoming worried?

 

[tonimxp]

Hi Guys, here is my work of these days available to the community.
The dimensions are 62 x 69 mm and I have also planned the use of silver mica capacitors ith only two 1206 smd capacitors.
I hope I did everything right, obviously any advice is welcome.
You will also notice some strange and seemingly insignificant pads, don't worry, they are put there to be able to use the card in plug-in mode for my Philips CD960.
This is my gift for the epiphany, I hope it is appreciated.
Antonio

 

[tonimxp]

Are you worried about becoming worried?

Well...maybe because I read that more than three ad844 would be needed for TDA1541?

 

[georgehifi]

Your quote is not altogether correct as that text refers to AD844, not AD811.

Parallel AD844s should have lower noise, but THD improvement is doubtful although lower input impedance may help. Costwise hard to see the point especially compared to the discrete BJT IV.

Sorry didn't look hard enough. But yes things do improove for the better when the 844 are stacked "without feedback", Barrie Gilbert AD's designer of the 844 agreed with that 5 years ago.
Quote from 2019:I was conversing with Barry Gilbert the designer of the AD844, he was very chuffed to see what we're doing with it without feedback and stacked for I/V stage. He was going to send me the proper schematic of everything inside it if he could find it, but he never did.

Cheers George

 

[tonimxp]

Hi Guys, here is my work of these days available to the community.
The dimensions are 62 x 69 mm and I have also planned the use of silver mica capacitors ith only two 1206 smd capacitors.
I hope I did everything right, obviously any advice is welcome.
You will also notice some strange and seemingly insignificant pads, don't worry, they are put there to be able to use the card in plug-in mode for my Philips CD960.
This is my gift for the epiphany, I hope it is appreciated.
Antonio

 

[tonimxp]

Hi Guys, here is my work of these days available to the community.
The dimensions are 62 x 69 mm and I have also planned the use of silver mica capacitors ith only two 1206 smd capacitors.
I hope I did everything right, obviously any advice is welcome.
You will also notice some strange and seemingly insignificant pads, don't worry, they are put there to be able to use the card in plug-in mode for my Philips CD960.
This is my gift for the epiphany, I hope it is appreciated.
Antonio

 

[tonimxp]

Add trimmers set near 4k to remove out offset to remove output caps.