Slones 11.4 'Blameless'

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#141
5th element said:
I assume you are referring to these. As I am in the process of getting a higher powered version of these built, I certainly want to make sure that the same thing doesn't happen again.😀
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they'll do fine, but actually I more thought of Thru' Hole, like these

or another possibility would be to use two 5.1k 1206's in series to divide the voltage. of course this way the gain would be slightly increased...

thanks for the ADC/DAC tip!
 
#143
soundcommand said:
Great thread and great work. Very informative.

A question - it may be in the thread and I missed it but what set up are you using to measure distortion? What is signal generator/analyzer set up? PC Based?

Thanks,
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Hello, thanks for the kind words and sorry about replying late to this.

I used an Maudio revolution 7.1 soundcard. I tapped the I2S lines and fed them into my own DAC and ADC boards. Two PCM1794s in mono mode and one PCM4202.

Recently however I purchased an Asus Xonar Essence ST. This card in itself gives superior performance with regards to distortion and noise to my construction. It is well worth the £150 or so, even if just for distortion measurements.

The Xonar uses Cirrus Logics top of the line ADC the CS5381, which is better then the PCM4202 when it comes to pure specs.

The Xonar also uses the PCM1792, which is identical to the PCM1794, the only difference between the two is how they are controlled. One uses a micro controller, the other is hard wired.

Chip and Spec wise the Xonar has rather excellent performance. It does not however, as it's advertised to, deliver audiophile performance when it comes to the sonics.

It sounds good, but nothing exceptional. Feeding the I2S lines out into my Dual mono PCM1794s, powered by super regulators, whoops the Asus' behind when it comes to sound.

I only got the Asus card yesterday, but I'm thinking of posting a review of it somewhere on DIYaudio, outlining its measured performance.
 
#144
Voltage coefficient of resistors

5th element said:
Eureka!

And what solved the problem? Changing the 10k resistor in the feedback network.

I was browsing Farnell and I noticed that the normal super saver 1206 1% 0.5 watt buy 50 a time, surface mount resistors that I buy were rated at 50 volts. This hadn't even crossed my mind as being a source for the distortion. I didn't figure that resistors really cared about the voltage they were given - unless they were going to be exposed to very high voltages.

Anyway, attached are two pictures showing the distortion with no load and then with the 9.4ohm load at almost 80v p-p.

I'm glad it turned out to be something like this, because quite frankly it wasn't making much sense.
Click to expand...

Thank you for the very useful information. It never occurred to me that
this component could have such a large effect.
 

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