Why use opamps ??

[clausdk]

For start lets say that i do not know anything about electronics, maybe a little less...

Today I removed the connection between the DAC and amplifier in my Zero, I was thinking that I maybe would get more power and less distorted power for the DAC, but I could not detect any difference..

As I was doing the above I removed the GDopamp in the zero and when I reconnected it, I forgot putting it back in much to my surprice it played anyway but with a sligtly different signature than with the opamp....

So for me the million $ question is why use does opamps at all ??

Because if I have learnt in my life it is that, the fewer the ingrediens the lesser mistakes is made underway..

And how much surplus of electronincs is there in our DAC/amps and so on ??

I have read that opamp just amplified the signal, but it also colours the result..

Is all DACs using opamps ??

What about Amps ??

I have about a 1000 more things I like to know but for now I will settle with this, I do not want to abuse the forum

[PinkFloyd]

Apr 5, 2009 20:30:10 GMT @clausdk said:

For start lets say that i do not know anything about electronics, maybe a little less...

Today I removed the connection between the DAC and amplifier in my Zero, I was thinking that I maybe would get more power and less distorted power for the DAC, but I could not detect any difference..

As I was doing the above I removed the GDopamp in the zero and when I reconnected it, I forgot putting it back in much to my surprice it played anyway but with a sligtly different signature than with the opamp....

So for me the million $ question is why use does opamps at all ??

Because if I have learnt in my life it is that, the fewer the ingrediens the lesser mistakes is made underway..

And how much surplus of electronincs is there in our DAC/amps and so on ??

I have read that opamp just amplified the signal, but it also colours the result..

Is all DACs using opamps ??

What about Amps ??

I have about a 1000 more things I like to know but for now I will settle with this, I do not want to abuse the forum

COST and SIZE.

[clausdk]

How is it cheaper and smaller than nothing ??

[Deleted]

Apr 5, 2009 20:30:10 GMT @clausdk said:

For start lets say that i do not know anything about electronics, maybe a little less...

Today I removed the connection between the DAC and amplifier in my Zero, I was thinking that I maybe would get more power and less distorted power for the DAC, but I could not detect any difference..

As I was doing the above I removed the GDopamp in the zero and when I reconnected it, I forgot putting it back in much to my surprice it played anyway but with a sligtly different signature than with the opamp....

So for me the million $ question is why use does opamps at all ??

Because if I have learnt in my life it is that, the fewer the ingrediens the lesser mistakes is made underway..

And how much surplus of electronincs is there in our DAC/amps and so on ??

I have read that opamp just amplified the signal, but it also colours the result..

Is all DACs using opamps ??

What about Amps ??

I have about a 1000 more things I like to know but for now I will settle with this, I do not want to abuse the forum

clausdk
To put it VERY simply,(also ignoring whether the DAC has a current or voltage output) opamps are normally used after DACs to isolate the DAC from cable capacitance and load impedance. DACs are not designed to drive cable and loads directly, and may also need among other things an increase in output level. Without the buffering opamp, the DACs will also become very sensitive to cable capacitance, and the sound will be markedly different sounding with different cable lengths.

I have read that opamp just amplified the signal, but it also colours the result..

So that statement is obviously incorrect.
Very few commercial DACs wouldn't use opamps, although some more upmarket ones may use a transformer instead.

SandyK

[clausdk]

So it is a kind of device that makes the output the same, so that I do not have to pay an insane amount of interest in the output from the dac.

And also something that protects the DAC against interference from "the outside world"

Have I got it right ??

Thanks

[Deleted]

Apr 5, 2009 23:55:52 GMT @clausdk said:

So it is a kind of device that makes the output the same, so that I do not have to pay an insane amount of interest in the output from the dac.

And also something that protects the DAC against interference from "the outside world"

Have I got it right ??

Thanks

Basically, yes.
Some DIY DACs may bypass the opamp section, but they usually are then best used only with short and low capacitance interconnects. The output level will often then not meet standard output level requirements, which MAY cause a few problems elsewhere.
SandyK

[rickcr42]

Basically, yes.Some DIY DACs may bypass the opamp section, but they usually are then best used only with short and low capacitance interconnects. The output level will often then not meet standard output level requirements, which MAY cause a few problems elsewhere.SandyK

all comes down to system matching and individual need so for instance in my case I rarely if ever have the need for the full scale digital 2V signal having in the signal patch a +20dB preamp and my power amps/headphone amps built to have a sensivitity of 500mV to 1V so i can eliminate the active output stage of just about all of my digital sources they being replaced with an output coupling capacitor (DC Blocking) and a line matching transformer (digital ground blocking,gentle slope passive single pole anti-aliasing filter) but as alex has stated this means I need to pay close attention to analog interconnect cable length and capaticance or I would be adding another pole of low pass filtration which could lead to audible signal attentuation at the high end.

The simple "fix" for me personally is to use a High-Current Buffer/ Cable Driver after the trafos for long cable runs,something that to me always sounds better than any monolithic op-amp (the old open loop buffer vs. feedback amp thingy) be it a monolithic or discrete buffer circuit with my personal faves being either the Linear Technologies LT1010 (with JFET front end) or a single ended mosfet with the former allowing for DC coupling while the latter requires a DC blocking cap at the output and if i DO need any additional gain,and that is a rarity,a simple class-a FET stage is my personal choice over again,the monolithic op amp choice for the reasons mentioned above

There are no absolutes in these things only personal needs to fit individual systems so you need to consider voltage and current'impedance drive needs then addres the solution on those parameters alone