Any good TDA1541A DAC kit?

[abraxalito]

Originally Posted by SoNic_real_one

You want to convince me that TDA1541 with max 4x OS capabilities will swing faster the outputs than the BB DAC's (rated at 8 and 16x) and the Phillips datasheet is wrong when it says the settling time is 1 micro second?

I think nowadays people use TDA1541A which has a plot of distortion vs freq at 8fs (fig4). Also what's the DNL spec for your beloved BB DACs - do you have it to hand?

[regal]

Originally Posted by SoNic_real_one

Well, to give you credit for something, I become curious to test the new, fast, low noise ADA4897-1 in my PCM61 DAC. I need an adaptor single-dual now...

Would this ADA4897-a make the issue of high input impedance of opamp I/V's with the dac rise time. Ie, would its input impedance not start to rise so far into the mhz that a DAC would never see it ?

[SoNic_real_one]

Originally Posted by abraxalito

I think nowadays people use TDA1541A which has a plot of distortion vs freq at 8fs (fig4). Also what's the DNL spec for your beloved BB DACs - do you have it to hand?

You made a funny
I was using BB DAC's as examples just because... they did build lots of r-2r dac's. BB developed many DACs in the ladder configuration - 16, 18, 20, another 20, 24 bit. Phillips developed... two r-2r: 14 and 16 bit.
And when BB was laser trimming their resistors, Phillips decided to continue their development of r-2r with TDA1543 - 16 bit with performance below 13 bit (-75dB)...

Originally Posted by regal

Would this ADA4897-a make the issue of high input impedance of opamp I/V's with the dac rise time. Ie, would its input impedance not start to rise so far into the mhz that a DAC would never see it ?

The DAC current is 1...2mA. Voltage 2V. That means 1..2 kohm resistance. I think the output impedance of the OpAmp that can drive 100 ohm at 1MHz and 80mA will be just fine. BTW it's a SiGe CMOS part...

[abraxalito]

Originally Posted by SoNic_real_one

You made a funny

I'm always hopeful that I can entertain as well as educate

I was using BB DAC's as examples just because... they did build lots of r-2r dac's. BB developed many DACs in the ladder configuration

Yep, but you missed out PCM53.

Phillips developed... two r-2r: 14 and 16 bit.

To borrow a phrase from Thorsten - this is patently untrue. You're as bad as him at digesting datasheets.

And when BB was laser trimming their resistors, Phillips decided to continue their development of r-2r with TDA1543 - 16 bit with performance below 13 bit (-75dB)...

You're talking full scale THD figures here? What's the relevance to audio? Oh and yet another patent falsehood

[SoNic_real_one]

Sure, has no relevance when it stings
I guess you did read the fable with fox and the grapes?

[abraxalito]

Yep I've read it - did you notice incidentally that my chosen I/V converter has worse specs than -75dB at full scale? Regal's given me some stick about that

[ThorstenL]

Hi,

Originally Posted by SoNic_real_one

You want to convince me that TDA1541 with max 4x OS capabilities will swing faster the outputs than the BB DAC's (rated at 8 and 16x) and the Phillips datasheet is wrong when it says the settling time is 1 micro second?

I never claimed that the Philips Chip settles faster than the BB ones. Nor have I indeed made any of the other claims you attribute to me.

The BB chip is rated to settle to +/-0.0006% of full scale, which is +/- 2LSB for 16 Bit and +/- 4LSB for 18 Bit. As for 1uS, this is TDA1541, I was referring to the later and by far more common TDA1541A which is specified to settle TO +/- 1LSB (+/-0.0003%) in under 500nS. It is anyones guess what the settling time to +/-4LSb would be like...

Past that, settling time TO +/-1LSB is much longer than the RISE TIME. And the rise time is what may cause a feedback amp to slew. It is also important to note that almost all I/V circuits are integrators, placing additional demands on the op-Amp to charge/discharge the integrator capacitor.

Originally Posted by SoNic_real_one

Well, to give you credit for something, I become curious to test the new, fast, low noise ADA4897-1 in my PCM61 DAC. I need an adaptor single-dual now...

Why?

According to you (post 186) 12V/uS slew rate is all that is needed. Maybe you should try a TL072 instead?

Ciao T

[ThorstenL]

Hi,

Originally Posted by SoNic_real_one

Phillips developed... two r-2r: 14 and 16 bit.

Philips never build R2R DAC's.Philips DAC's have always used active switched current sources and multi-emitter transistor dividers.

Ciao T

[ThorstenL]

Hi,

Originally Posted by abraxalito

You're as bad as him at digesting datasheets.

What part of which datasheet did I get wrong? My quip about the Fet switches in you favourite VGA? If they do not use switches, what do they use, do you have any reference that shows what is used?

Ciao T

[abraxalito]

Originally Posted by ThorstenL

What part of which datasheet did I get wrong? My quip about the Fet switches in you favourite VGA?

Yep. Incidentally it was a little more than a 'quip' but we'll let that slide for now

If they do not use switches, what do they use, do you have any reference that shows what is used?

Why would you believe what I say when you don't believe what ADI says? I'd only be quoting from that - that DS and the related parts using the same architecture plus ADI's design support materials are my only source.

Even if you didn't read the explanations the fact that the attenuation vs control voltage plots are smooth without step jumps might tell you something which undermines your FET switch opinion.