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-   -   First cycle distortion - Graham, what is that? (https://www.diyaudio.com/forums/solid-state/32758-cycle-distortion-graham.html)

bimo 16th December 2020 12:37 AM

Quote:

Originally Posted by nattawa (https://www.diyaudio.com/forums/solid-state/32758-cycle-distortion-graham-post6449705.html#post6449705)
……Yes, but not with straight Miller compensation, which is what petr_2009's amp being on topic is.

You can have relative high slew rate with only Miller compensation if use high current in LTP.

petr_2009 16th December 2020 03:22 AM

3 Attachment(s)
A colleague approached me and thanked me for bringing up the topic of vector distortion measurements using the Baksandall and Hafler methods.
Since Hafler's method is the simplest and does not require anything other than an oscilloscope, he decided to test his amplifier using a 1 kHz square wave signal.
By changing the correction, he managed to reduce the signal transit time by 4 times, which had a positive effect on the sound quality. But since he did not manage to lower it below 100 ns, he decided to make a new amplifier.
I also checked both models with this method, here are the test results

petr_2009 16th December 2020 04:55 AM

4 Attachment(s)
slew rate can be measured in two ways

jan.didden 16th December 2020 07:00 AM

Of course it can be done. Pretty much anything can be done - it's just engineering.

By the way can we agree to use 'compensation' for compensation rather than 'correction', and 'square wave' rather than 'meander' for a square wave?
I understand that we are not all native English speakers (I'm not) but a common vocabulary helps understanding. Thanks all.

Jan

jan.didden 16th December 2020 07:04 AM

Quote:

Originally Posted by petr_2009 (https://www.diyaudio.com/forums/solid-state/32758-cycle-distortion-graham-post6450686.html#post6450686)
slew rate can be measured in two ways

That 2nd and 4th graph doesn't look like slew rate but rather like rise time. Slew rate would look like a straight line.

Jan

chip_mk 16th December 2020 07:46 AM

Quote:

Originally Posted by petr_2009 (https://www.diyaudio.com/forums/solid-state/32758-cycle-distortion-graham-post6450652.html#post6450652)

Since Hafler's method is the simplest and does not require anything other than an oscilloscope, he decided to test his amplifier using a 1 kHz square wave signal.

The upper trace, what amp generated that trace? What amp was used as a Driving amp from the picture?

BTW really smart test setup

petr_2009 16th December 2020 10:18 AM

2 Attachment(s)
in fact, the basic version of the Self amplifier does not pull at 150 kHz without distortion, but only 125 kHz. So I repeated the measurements

scottjoplin 16th December 2020 12:28 PM

Quote:

Originally Posted by petr_2009 (https://www.diyaudio.com/forums/solid-state/32758-cycle-distortion-graham-post6450652.html#post6450652)
By changing the correction, he managed to reduce the signal transit time by 4 times, which had a positive effect on the sound quality.

What was the nature of that effect and can you explain it?

petr_2009 16th December 2020 01:46 PM

Quote:

Originally Posted by jan.didden (https://www.diyaudio.com/forums/solid-state/32758-cycle-distortion-graham-post6450738.html#post6450738)
Of course it can be done. Pretty much anything can be done - it's just engineering.

By the way can we agree to use 'compensation' for compensation rather than 'correction', and 'square wave' rather than 'meander' for a square wave?
I understand that we are not all native English speakers (I'm not) but a common vocabulary helps understanding. Thanks all.

Jan

Jan, square wave in Russian just "meander"
I don't know much English, I mostly use a translator

jan.didden 16th December 2020 01:52 PM

I understand, just want to help.
I can make the connection from meander to square wave, meander we also know in Dutch.

Jan


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