Hello everyone,
I am pleased to announce the release of version 3.0 of the Q17-Mini, the result of several months of research and testing.
The Q17-Mini 3.0 is a complete redesign of the PCB component implementation. The objective was to increase the performance of the amplifier in terms of the signal-to-noise ratio and others technicals points. It is also much easier to solder (and unsolder).
The new PCB is built on star and zone ground topology to reduce noise and interference. Track lengths were greatly reduced and copper usage reduced by 70%. The PCB is also much less capacitive.
Here are the main new features
The Gerbers files, measurements and documentation are available on my Github repository in the Q17-Mini-3.0 directory.
Have fun.
Stef.
I am pleased to announce the release of version 3.0 of the Q17-Mini, the result of several months of research and testing.
The Q17-Mini 3.0 is a complete redesign of the PCB component implementation. The objective was to increase the performance of the amplifier in terms of the signal-to-noise ratio and others technicals points. It is also much easier to solder (and unsolder).
The new PCB is built on star and zone ground topology to reduce noise and interference. Track lengths were greatly reduced and copper usage reduced by 70%. The PCB is also much less capacitive.
Here are the main new features
- Complete new PCB design and components placement.
- Same PCB size, mounting holes and power transistor locations as v2.
- Removed all thermal brakes and VIAs.
- Removed R32.
- Removed C18 and C19. They are not needed with low ESR capacitors.
- Added D7 and D8 zener protection (MMSZ5245C).
- Merged GND / GNDPWR ground and built a new ground plane using GND zones and star topology.
- Better thermal management on the PCB.
- Updated diagram to 2.3.
- Updated iBOM Q17-Mini-BOM file.
The Gerbers files, measurements and documentation are available on my Github repository in the Q17-Mini-3.0 directory.
Have fun.
Stef.
Attachments
Hello,
I compared the THT and SMD version of Q17.
THT: Q11, Q111 = BS250P, Q7 = LKS170B
SMD: U2 = NDC7003P, Q7' = JFE150
The opamp is the same, namely an OPA1611.
The scope measurements, spectrum and bandwidth are identical. There is just a small difference on these two curves.
Distortion is slightly lower with SMD components. I don't think it's possible to hear the difference.
Stef.
I compared the THT and SMD version of Q17.
THT: Q11, Q111 = BS250P, Q7 = LKS170B
SMD: U2 = NDC7003P, Q7' = JFE150
The opamp is the same, namely an OPA1611.
The scope measurements, spectrum and bandwidth are identical. There is just a small difference on these two curves.
Distortion is slightly lower with SMD components. I don't think it's possible to hear the difference.
Stef.
Attachments
Hello,
I uploaded to the Github repository an updated version of the Q17-Mini 3.0 diagram with updated measurements and a new value for R6 of 196R instead of 182R for the 1.2V sensitivity.
Regards,
Stef.
I uploaded to the Github repository an updated version of the Q17-Mini 3.0 diagram with updated measurements and a new value for R6 of 196R instead of 182R for the 1.2V sensitivity.
Regards,
Stef.
Attachments
Hello,
I worked on a power transistor optimization table and tried to find new transistor couples more suited to the Q17.
The resistance values for R7/R17 allow the cut-off frequencies of the transistors to be correctly adjusted andand thus avoid overflow.
In red, this is the current configuration since the original FQA/FQP pairs are no longer available.
I plan to try some of the new pairs in blue in the table in a few weeks but if anyone already has these transistors in stock they can try them (a scope is needed to check the result).
Regards,
Stef.
I worked on a power transistor optimization table and tried to find new transistor couples more suited to the Q17.
The resistance values for R7/R17 allow the cut-off frequencies of the transistors to be correctly adjusted andand thus avoid overflow.
In red, this is the current configuration since the original FQA/FQP pairs are no longer available.
I plan to try some of the new pairs in blue in the table in a few weeks but if anyone already has these transistors in stock they can try them (a scope is needed to check the result).
Regards,
Stef.
Attachments
Hello,
Here is a new version v1.1.3 of the power transistor table for the Q17.
I added 2 new pairs of transistors and the Gfs and EOL columns.
I downloaded the PDF version of the file on my Github repository.
The 2SK3564 used for Q6 has been declared End Of Life. It therefore becomes urgent to find new pairs.
Regards,
Stef.
Here is a new version v1.1.3 of the power transistor table for the Q17.
I added 2 new pairs of transistors and the Gfs and EOL columns.
I downloaded the PDF version of the file on my Github repository.
The 2SK3564 used for Q6 has been declared End Of Life. It therefore becomes urgent to find new pairs.
Regards,
Stef.
Attachments
Stef
Why not IXTH44P15T:
www.mouser.dk/datasheet/2/240/media-3321593.pdf
It seems like the closest alternative to FQA36P15.
Only problem is probably the gate capacitance?
Why not IXTH44P15T:
www.mouser.dk/datasheet/2/240/media-3321593.pdf
It seems like the closest alternative to FQA36P15.
Only problem is probably the gate capacitance?
And what about IXTP36P15.
This is available in contrast to IXTH36P15. I know th P is in a TO220 house, but that should not be a problem?
This is available in contrast to IXTH36P15. I know th P is in a TO220 house, but that should not be a problem?
Hello,
IXTH44P15T: In my humble opinion, 35 Khz of bandwidth for an Ciss of 13nF with 330R. No need to even try it, it's way too low and out of step with Q6 variantes.
v1.1.5 with new pairs and some mods.
https://github.com/stefaweb/Q17-Amp...3.0/Q17-Power-Transistors-Selection-1.1.5.pdf
For now, the best pair seems to be the IXTQ50N20P / IXTQ52P10P. I ordered a few to try because until now, I lived with my stock of FQA46N15 / FQA36P15.
I tried the FQA46N15 / IXTH48P20P pair recommended on the forum, the result is not as good as the FQA46N15 / FQA36P15 pair.
I tried the Exicons in simulation. I can't get the Q17 circuit to work with Exicons under LTSpice at the moment. Whatever the combinations (R11-R12/R10-R13/R14-R15), I obtain a very nice machine with odd harmonics without even harmonics. I tried at 35V, 42V and 50v. 🤢
If you're interested, I can post the current LTSpice sim with the Exicons here. Someone else might have better luck than me.
Stef.
IXTH44P15T: In my humble opinion, 35 Khz of bandwidth for an Ciss of 13nF with 330R. No need to even try it, it's way too low and out of step with Q6 variantes.
v1.1.5 with new pairs and some mods.
https://github.com/stefaweb/Q17-Amp...3.0/Q17-Power-Transistors-Selection-1.1.5.pdf
For now, the best pair seems to be the IXTQ50N20P / IXTQ52P10P. I ordered a few to try because until now, I lived with my stock of FQA46N15 / FQA36P15.
I tried the FQA46N15 / IXTH48P20P pair recommended on the forum, the result is not as good as the FQA46N15 / FQA36P15 pair.
I tried the Exicons in simulation. I can't get the Q17 circuit to work with Exicons under LTSpice at the moment. Whatever the combinations (R11-R12/R10-R13/R14-R15), I obtain a very nice machine with odd harmonics without even harmonics. I tried at 35V, 42V and 50v. 🤢
If you're interested, I can post the current LTSpice sim with the Exicons here. Someone else might have better luck than me.
Stef.
Last edited:
IMHO the IXYS .....P10 has too low breakdown voltage . Cannot operate them safely with +/- 50 V
Complicated to make pairs for that circuit. ☕
Have a Vgs(th) in the same range.
Have a Gfs transconductance high and close.
Have a Ciss low enough to have a good bandwidth.
Have a Vgs(th) in the same range.
Have a Gfs transconductance high and close.
Have a Ciss low enough to have a good bandwidth.
That's right, but I still think IXTP36P15 have all these parameters correct, it is very close to the FQA36P15 except for the housing, but heattransfer is not that problematic in an amplifier like Q17. The output runs in class B so not very heat sensitive. I feel it is a much better compromise than reduced bandwidth or too low break down voltage.
Nice.
The Q5/Q6 heat up more than the Q14/Q15. 😉
I had seen the IXTx36P15P but I didn't take it into account since it is not available in a TO247 (IXTH36P15P) or TO-3P (IXTQ36P15P) package.
It looks like a clone or it may be the same ones that came from the same factory which seems to have stopped their production.
Stef.
The Q5/Q6 heat up more than the Q14/Q15. 😉
I had seen the IXTx36P15P but I didn't take it into account since it is not available in a TO247 (IXTH36P15P) or TO-3P (IXTQ36P15P) package.
It looks like a clone or it may be the same ones that came from the same factory which seems to have stopped their production.
Stef.
Excatly Q5/Q6 runs class A and Q14/Q15 runs class B
IXTP36P15 are apparently not out of production. Mouser has 63 of them and expect 550 pas in March 25 and 400 in april.
IXTP36P15 are apparently not out of production. Mouser has 63 of them and expect 550 pas in March 25 and 400 in april.
On the original Quad 405 there was 0.7v the class A circuit had to drive through before the outputs come on. With FETs there will be 6.5v to overcome. 5200 and 1945 BJTs may work better.