Computer-Based Distortion Analyzers

[1audio]

I have used them for years. The Juli@ interface is a very good one. The ADC and DAC are not the best available but close. You can use an external DAC and ADC to get even better performance. Typical price is between $100 and $125.

 

[thimios]

I have used them for years. The Juli@ interface is a very good one. The ADC and DAC are not the best available but close. You can use an external DAC and ADC to get even better performance. Typical price is between $100 and $125.

Thanks for reply.
use an external DAC and ADC to get even better performance
more datails please,give me an example

 

[1audio]

The lowest distortion ADC I have been able to find is the AK5394A. I have one of the AKD5394A boards I have made a few changes to. I couple it to the SPDIF input of the Juli@ for critical measurements that I can't make other ways.

 

[thimios]

The lowest distortion ADC I have been able to find is the AK5394A. I have one of the AKD5394A boards I have made a few changes to. I couple it to the SPDIF input of the Juli@ for critical measurements that I can't make other ways.

Thanks ,Esi Julia is enough for me now ,i can't afford the cost of this expensive ADC.

 

[thimios]

distortion measurements.

Someone having experience with this?thd-measurement

 

[altor]

Someone having experience with this?thd-measurement

10-15 years ago, this might be good...

 

[thimios]

10-15 years ago, this might be good...

An oscillator THD down to 0.0005% is something old for today?

 

[altor]

An oscillator THD down to 0.0005% is something old for today?

Yes

If it will be for full frequency range - it will be nice, but for a fixed frequency - not.

For example, Victor's oscillator:
Ultra Low Distortion 0 00001 1kHz Sine Generator Assembled and Tested PCB | eBay

this is much simple, and THD is 50(!) times better.
Schematic is not a "top secret", if to "DIY" it is not more expensive then TurnerAudio's design.

What is really worth in Victor's design - is 35v power. I'm really tired to charge every time 5x9V NiMH batteries

 

[thimios]

Yes

If it will be for full frequency range - it will be nice, but for a fixed frequency - not.

For example, Victor's oscillator:
Ultra Low Distortion 0 00001 1kHz Sine Generator Assembled and Tested PCB | eBay

this is much simple, and THD is 50(!) times better.
Schematic is not a "top secret", if to "DIY" it is not more expensive then TurnerAudio's design.

What is really worth in Victor's design - is 35v power. I'm really tired to charge every time 5x9V NiMH batteries

That is really good!

 

[Kastor L]

Ultra Low Distortion 0 00001 1kHz Sine Generator Assembled and Tested PCB | eBay

Very nice looking thank you for the link.

 

[1audio]

Yes

If it will be for full frequency range - it will be nice, but for a fixed frequency - not.

For example, Victor's oscillator:
Ultra Low Distortion 0 00001 1kHz Sine Generator Assembled and Tested PCB | eBay

this is much simple, and THD is 50(!) times better.
Schematic is not a "top secret", if to "DIY" it is not more expensive then TurnerAudio's design.

What is really worth in Victor's design - is 35v power. I'm really tired to charge every time 5x9V NiMH batteries

I use 4 disposable 9V batteries and I hacked the resistor in series into a current source using an LM317. I can get 10 hours at least from it, probably more. But you don't need to leave it on.

 

[altor]

I use 4 disposable 9V batteries and I hacked the resistor in series into a current source using an LM317. I can get 10 hours at least from it, probably more. But you don't need to leave it on.

I know this solution, but disposable batteries are too expensive, so I use rechargeable, which have the lower loaded voltage (~8v) and higher open circuit after the charging (~10.5v). I use simple linear regulator (lm317).

It is a difference - to use oscillator for periodically testing, or to develop ADC and run oscillator continuously.
Sometimes I run it from the Lab.Power Supply (btw - have not seen the difference).

 

[1audio]

You should still replace the series resistors current limiter with an LM317 strapped as a current source. It will extend the battery life considerably.

 

[31697B]

I just use a nice little, clean bench supply.


THx-RNMarsh

 

[altor]

You should still replace the series resistors current limiter with an LM317 strapped as a current source. It will extend the battery life considerably.

Yes, you are right. Which value of these resistors you use?
The current is 30-35mA?

I should modify it, now I use 317 as 34.5v voltage source, but I think to replace the batteries with AC power supply with small transformer.

 

[1audio]

Here is how I set up the oscillators: http://www.diyaudio.com/forums/equi...n-audio-range-oscillator-357.html#post3905078 I have three so a bench supply would be impractical and I wanted to really isolate from the line since even a little bit of leakage could be indistinguishable from supply problems in the DUT. Three supplies and defective batteries from eBay pushed me into the disposable batteries. Not shown was bypassing the onboard resistors.