Made with KiCad.
I used Sprint-Layout 5 about ten years ago.
I'm going to be out. I'll resume testing in a few days.
Stef.
I used Sprint-Layout 5 about ten years ago.
I'm going to be out. I'll resume testing in a few days.
Stef.
Hello,
I updated the transistor table for you.
I had time to finish testing the FQA46N15 / IXTH48P20P pair. In the end, the only thing that changes to remove the small overshoot is R15 which goes down to 150R instead of 330R. I updated the various documents on the Github repository.
I also tested the FQPF3N80C in Q6 instead of the 2SK3564. It works better with the FQPF3N80C. There is no longer this small oscillation on Q6 when we arrive close to the clip (which can be seen at the output). This is good since the 2SK3564 is EOL. We didn't have this oscillation with the original FQP3N30. I will update the information on the Github when I come back.
Regards,
Stef.
I updated the transistor table for you.
I had time to finish testing the FQA46N15 / IXTH48P20P pair. In the end, the only thing that changes to remove the small overshoot is R15 which goes down to 150R instead of 330R. I updated the various documents on the Github repository.
I also tested the FQPF3N80C in Q6 instead of the 2SK3564. It works better with the FQPF3N80C. There is no longer this small oscillation on Q6 when we arrive close to the clip (which can be seen at the output). This is good since the 2SK3564 is EOL. We didn't have this oscillation with the original FQP3N30. I will update the information on the Github when I come back.
Regards,
Stef.
Attachments
Last edited:
Hi All
Finally got time to do some measurements 😀
This is a 10 Khz square wave 7.75 V into 4 Ohms .
One channel with original FQA36P15 and the other with ITXP36P15.
Both channel driven simultaneously.
First scope photo is with the 2 channels shown separately with offset on the scope screen and the next with no offset on the screen - the to traces is on top of each other.
Absolutely no difference between the 2 channels!!
And I didnt even change the gate resistor : All gate resistors 330 ohms
Finally got time to do some measurements 😀
This is a 10 Khz square wave 7.75 V into 4 Ohms .
One channel with original FQA36P15 and the other with ITXP36P15.
Both channel driven simultaneously.
First scope photo is with the 2 channels shown separately with offset on the scope screen and the next with no offset on the screen - the to traces is on top of each other.
Absolutely no difference between the 2 channels!!
And I didnt even change the gate resistor : All gate resistors 330 ohms
Attachments
Hi,
Thanks for the measures.
I'm back and I received the IXTQ36P15P to try.
I still haven't found (understood) why I have this difference with the gate resistor and the overshoot (and the spectrum).
The problem is that I don't use the same circuit as the original circuit so it's difficult to compare.
Here a an example. The only thing that changes is Q16.
Config S1: FQA46N15 + FQA36P15
Config S5: FQA46N15 + IXTQ36P15P
I tried with the driver config D1, D2 and D3. No difference.
No spectrum difference with gate resistor with the default 330R.
See table. I posted a new PDF version of the Github repository. I also enclosed a zip file with all the curves.
Regards,
Stef.
Thanks for the measures.
I'm back and I received the IXTQ36P15P to try.
I still haven't found (understood) why I have this difference with the gate resistor and the overshoot (and the spectrum).
The problem is that I don't use the same circuit as the original circuit so it's difficult to compare.
Here a an example. The only thing that changes is Q16.
Config S1: FQA46N15 + FQA36P15
Config S5: FQA46N15 + IXTQ36P15P
I tried with the driver config D1, D2 and D3. No difference.
No spectrum difference with gate resistor with the default 330R.
See table. I posted a new PDF version of the Github repository. I also enclosed a zip file with all the curves.
Regards,
Stef.
Attachments
Hi Steff
Those measurements also confirms , that ITX(x)36P15 is a fully compatible substitute for FAQ36P15 and that is good news for all DIY audiophiles.
They can now make this wonderful😛😛😛 amp.👍👍👍
Those measurements also confirms , that ITX(x)36P15 is a fully compatible substitute for FAQ36P15 and that is good news for all DIY audiophiles.
They can now make this wonderful😛😛😛 amp.👍👍👍
Most probably the FQA46/36 are more complementary than the FQA/ITX combo.
This will lead to a worse/poor THD spectrum
This will lead to a worse/poor THD spectrum
Try to do a Spectrum, just to confim. No hurry. 😉
I'll eventually find out where it comes from.
The FQA46N15 / IXTH48P20P pair is not bad too. The 32/36 siemens for Gfs is good for push pool. I listened to it quickly in comparison to Farchild. It's drier and faster subjectively. At first glance the slightly less good spectrum does not seem to be heard. I have not yet listened with the IXTQ36P15P.
I ordered the N version IXTQ36N30P to see too.
Stef.
I'll eventually find out where it comes from.
The FQA46N15 / IXTH48P20P pair is not bad too. The 32/36 siemens for Gfs is good for push pool. I listened to it quickly in comparison to Farchild. It's drier and faster subjectively. At first glance the slightly less good spectrum does not seem to be heard. I have not yet listened with the IXTQ36P15P.
I ordered the N version IXTQ36N30P to see too.
Stef.
Attachments
Tried another pair - > IXTQ36N30P / IXTQ36P15P (config S4)
This is the pair with the worst measurements but the hottest sound. I need to listen again to the FQA46N15 / IXTH48P20P and FQA46N15 / IXTQ36N30P pair to refine.
I started to put listening comments in front of the configurations in the table.
I have 2 boards. One with the original configuration in all Farchild FQA / FQP. On the second board, I change Q15 and Q16 accordingly. I switch from one to the other board in mono on a high sensitivity speaker.
Stef.
This is the pair with the worst measurements but the hottest sound. I need to listen again to the FQA46N15 / IXTH48P20P and FQA46N15 / IXTQ36N30P pair to refine.
I started to put listening comments in front of the configurations in the table.
I have 2 boards. One with the original configuration in all Farchild FQA / FQP. On the second board, I change Q15 and Q16 accordingly. I switch from one to the other board in mono on a high sensitivity speaker.
Stef.
Attachments
Hi Steff
There must be something else different between your 2 modules besides the two P-Mosfets.
Attached is the FFT measurements I made on the two modules, one with the FQA36P15 and one with ITXP36P15 and again there are absolutely no difference in performance.
My measuring system is not as good as yours, just a soundcard and a free Visual Analyzer on a PC, but the differences should be visible on this too!
There must be something else different between your 2 modules besides the two P-Mosfets.
Attached is the FFT measurements I made on the two modules, one with the FQA36P15 and one with ITXP36P15 and again there are absolutely no difference in performance.
My measuring system is not as good as yours, just a soundcard and a free Visual Analyzer on a PC, but the differences should be visible on this too!
Attachments
Thanks. it is very good. My measures are took at 1W (2.83Vrms).
I will think about it.
Many odd harmonics in the curves?
Stef
I will think about it.
Many odd harmonics in the curves?
Stef
Probably some of them are spuriouses. The change depending on sampling frequency and sample points, so don't put too much into that. The main thing is that the spectrum is the same no matter what P-Mos I use.
Yes, the principle is that it does not move.
To have a "standard", I took out a Q17-Mini 1.3 prototype from the archives. That is to say the same circuit and component as you (but with only one pair).
I just passed C7 to 2.2uF to have a flat bandwidth. Ok with the scope.
S1 config (FQA46N15 / FQA36P15) with D2 config.
I will try the IXTH48P20P in Q16 later to see if it moves.
Stef.
To have a "standard", I took out a Q17-Mini 1.3 prototype from the archives. That is to say the same circuit and component as you (but with only one pair).
I just passed C7 to 2.2uF to have a flat bandwidth. Ok with the scope.
S1 config (FQA46N15 / FQA36P15) with D2 config.
I will try the IXTH48P20P in Q16 later to see if it moves.
Stef.
