Q17 - an audiophile approach to perfect sound

[iTiberius]

The best way, is to measure parts before mounting. However, in this case, you may measure Vgs on each BS250 with circuit power on. The value is less important. What matter most is that Vgs to be very close on each other.

Regards,
Tibi

 

[ed linssen]

The best way, is to measure parts before mounting. However, in this case, you may measure Vgs on each BS250 with circuit power on. The value is less important. What matter most is that Vgs to be very close on each other.

Regards,
Tibi

Hi Tibi,

I am still not sure about the next values:

R29/30: 10 Ohm or 100 Ohm- or 10KOhm? (The pcb says 10K, the Bom says 10 Ohm)

R23 ;10K Ohm or 8K2Ohm?

Q3 : KCS 1845?

Q2 : 2SQ970/KSA992?

C3 : 100mF 10Volt Bipolair? (Preferably)?

C16 : is it oké to use the higer temp (105C) version iso the 85C version? This one is in stock at Mouser's atm.

Thank you
Ed

 

[iTiberius]

R29=R30=10ohm You may use up to 100ohm.
Q3=2SC2240=KSC1845
Q2=2SA970=KSA992
C2=100uF/10V bipolar
C3=C6=100uF/25V
For C16 use normal 85C capacitors, not low ESR or ESL.
Physically bigger caps sound sensible better.

Regards,
Tibi

 

[ed linssen]

R29=R30=10ohm You may use up to 100ohm.
Q3=2SC2240=KSC1845
Q2=2SA970=KSA992
C2=100uF/10V bipolar
C3=C6=100uF/25V
For C16 use normal 85C capacitors, not low ESR or ESL.
Physically bigger caps sound sensible better.

Regards,
Tibi

Thank you Tibi! That will do it.

 

[manniraj]

Hi Tibi,

I am still not sure about the next values:

R29/30: 10 Ohm or 100 Ohm- or 10KOhm? (The pcb says 10K, the Bom says 10 Ohm)

R23 ;10K Ohm or 8K2Ohm?

Q3 : KCS 1845?

Q2 : 2SQ970/KSA992?

C3 : 100mF 10Volt Bipolair? (Preferably)?

C16 : is it oké to use the higer temp (105C) version iso the 85C version? This one is in stock at Mouser's atm.

Thank you
Ed

Did you get a response on R23 ;10K Ohm or 8K2Ohm?

 

[iTiberius]

I settled at R23=8k2
Will work just fine with R23=10K.

Regards,
Tibi

 

[smk7]

Took measurements. For comparison, I made measurements of the Nikitin amplifier. The load is 4 ohms.

 

[iTiberius]

Thank you for your measurements, smk7.

Regards,
Tibi

 

[stef1777]

Thanks smk7.

Same PSU for amps measures?

Regards,

Stef.

 

[smk7]

The load is 4 ohms. The first picture is 5V amplitude, the second 10V amplitude. Frequency 1 kHz and 20 kHz, respectively

 

[smk7]

Power supply voltage +/- 35V

 

[smk7]

 

[ejp]

Power supply voltage +/- 35V

Why? A real 405 has +/-50V.

 

[iTiberius]

Q17 was designed to run at +/-50Vdc, but If you run Q17 at lower voltage +/-35Vdc, than R25 must be adjusted to ~2k2.
Even the measurements are done at +/-35Vdc these show impressive performance.
There are few amplifiers that may reach THD 0.00X% and from my knowledge none in class B.
What matter most is how Q17 sound, because I have designed this amplifier with the goal of a high dynamic and top resolution sound.

While I appreciate measurements, I would like to see your words about amplifier sound. This is all that matter in the end.

Regards,
Tibi

 

[smk7]

than R25 must be adjusted to ~2k2.

it is done

 

[smk7]

Why? A real 405 has +/-50V.

The real QUAD has a different scheme.

 

[smk7]

While I appreciate measurements, I would like to see your words about amplifier sound. This is all that matter in the end.

No time yet to put together a second channel. But even one can hear that it sounds interesting. It's worth building.

 

[iTiberius]

This to announce that I have updated zip file in the very first post of this thread with new source files and gerbers. This include a Q17 version with two pairs.

Enjoy !

Regards,
Tibi

 

[stef1777]

Hi Tibi,

I don't see update on your Github repository?

Stef.

 

[iTiberius]

I want to update documentation too and I'm a bit slow with words.

Regards,
Tibi