Q17 - an audiophile approach to perfect sound

Hello,

I have built another Q17, this time a copy of the flatter one, but with soft start, speaker delay and speaker protection circuit, and radio controlled potentiometer.
Plays great.

Regards Tim
 

Attachments

  • DSCN7895 (Groß).JPG
    DSCN7895 (Groß).JPG
    74.2 KB · Views: 213
  • IMG_20211219_093926_i.jpg
    IMG_20211219_093926_i.jpg
    143.8 KB · Views: 200
Hello,

Just to let you know that the Q17-Mini's production PCB 1.1.1 works without a hitch. I built one and installed it in the cabinet.

One board consume 11.5W.

On the other hand, I have to order components for the second card again. With all my tests and burnt components, I am missing some now.

Cheers,

Stef.
 

Attachments

  • IMG_6554.jpeg
    IMG_6554.jpeg
    495.8 KB · Views: 175
  • IMG_6555.jpeg
    IMG_6555.jpeg
    212.6 KB · Views: 166
Last edited:
No, I would like to keep the prototype to tinker with and assemble a board with the final PCB to put in the cabinet.

I'm still going to tinker to use both cards at the same time to test in stereo.

Tibi, could you look on Mouser to find me a suitable Schottky diode? I am a little lost with all these references, the Fv which are given for different consumption and the out of stock problem.

Stef.
 


Sorry Tibi but there must be something I didn't understand.

The 1N5819 is given for a Fv of 450mV far away from 350mV.

Stef.


And this 1N5819 from ST?
https://www.mouser.fr/datasheet/2/389/cd00001625-1795544.pdf
Or the SB series from Vishay?
https://www.mouser.fr/datasheet/2/427/VISH_S_A0003154141_1-2568705.pdf
 

Attachments

  • 1N5819 -data.jpg
    1N5819 -data.jpg
    132.8 KB · Views: 91
Hello Tibi,

I built the amp because the first one
https://www.diyaudio.com/community/...approach-to-perfect-sound.374507/post-6776372
has already moved out to an excessive speaker hobbyist and I want to have that as a comparison, also to test the additional comfort functions. It is nearly the same, but with a 120VA 2x 24V Transformer (even less Current).
Currently I am building an amplifier based on the latest PCB creation of mine, which contains additional components and of course I want to know if these modifications somehow make themselves noticeable.

Regards Tim
 
Hello,

I can now make a comparison:
the one amplifier corresponds to this setup:
https://www.diyaudio.com/community/...approach-to-perfect-sound.374507/post-6776342This one plays especially airy, exceptionally natural.

With the new amplifier I have integrated more components to test their effects:
1. a subber link at Q12, this reduces the resolution, the stage becomes narrower.
I removed the subber at Q12 first, it disturbs.

2. resistors against ground at the signal paths to the end transistors, this has no audible effect (after the simulation should also only show an effect with some more end transistors).
The resistors against ground are also removed. They showed no effect in this variant.

3. R11 and R12 are 51 Ohm
This is also a stupid idea, contrary to the simulation the amp becomes more unstable, the DC offset increases to 56 mV. After it warmed up a bit it didn't find a DC operating point, only after reducing it to 47 ohms it works as usual.

4. R3 is 100 Ohm
I cannot say anything about this yet.

5. C-Q5 and C-Q6 is 470pF
This has a subtle effect, it takes away some airiness and leads to a more precise structuring of the acoustic stage, the amp tends to play more analytically.

6. the PCB is very much downsized and there are 2200 uF installed (cup electrolytic capacitor), on the other only 820 uF (low ESR). The cup electrolytic capacitor does not seem ideal, the bass is more controlled and therefore a bit more restrained.

My conclusion: Q17 tuning is nearly impossible - so I say: Tibi you did an excellent job.

Regards Tim