Hunting for 200MHz+, 16bit, 4ch DSO -> What's good?

[rsjsouza]

I would also take a look at this other thread:
https://www.eevblog.com/forum/testgear/instrument-for-audio-signal-analysis/

For clean sinewave generation suitable for THD measurements, perhaps a Keithley 2015 would suit your needs.

I have also heard that a Krohn Hite 4402B sinewave generator is good for audio distortion measurements.

[Mechatrommer]

I've always had with sound from a PC is stray noise.

this applied to anything (PC cards and USB plugged devices), i guess including the $10K lecroy, rigol etc, when..... you have a turned ON PC (or high powered SMPS) right next to the measurement setup... thats why any serious lab measurement setup will bluntly rule out any USB plugged devices..

[nctnico]

I've always had with sound from a PC is stray noise.

this applied to anything (PC cards and USB plugged devices), i guess including the $10K lecroy, rigol etc, when..... you have a turned ON PC (or high powered SMPS) right next to the measurement setup... thats why any serious lab measurement setup will bluntly rule out any USB plugged devices..

For that purpuse there are USB isolators or you can use a seperate ADC which is then connected to the PC through optical fibers. A PC and a good audio card really are the best low cost solution for doing work on audio. You maximise the benefit of riding along high volume precision ADC/DAC chip development.

[CPitts]

I really like where this discussion has gone and keep it up!

I'm trying to avoid having racks of equipment.  I've been there and done that stuff with gear before and I don't have an abundant desire to just collect stuff to build up a big wall of dials, buttons and flashing lights.

I'm warming to the idea of fibre connected siggen (for EMI control) with a DSP or similar to drive a DAC and ADC with high quality output stage.

I do need something at the circuit end where I can put probes against pins and read the signal as it moves through a circuit board or set of components.  This WILL include a signal that's post amplification stage so greater than line level.  All conversation to date in other threads says this isn't a soundcard.

I'm trying to avoid building my own equipment but I can really see the advantage of what blueskull has done and am quite interested in that as an option!

I still can't seem to get past the need for a scope to see the signal at pins through a circuit board.

There must be something that I'm missing in this part of the process.  What's the obvious thing that am I missing here, or is a DSO the right tool in that part of the process?

[nctnico]

In general you work in stages: an oscilloscope can be used to check the shape and presence of a signal. The next stage is to use a different device if you need to measure particular signal properties which an oscilloscope typically can't do. Although more and more gets included into modern DSOs an oscilloscope isn't a very precise instrument. DC vertical accuracy can be as bad as 3% (0.26dB) and at higher frequencies all bets are off.