PL14_20 Revision D Control Board Assembly now available

[laatsch55]

Damn Joe and Lee - it seems you guys are taking some tremendous strides here


Remember Dennis, I'm just the shop rat here...

 

[NavLinear]

Here's a new avatar for you. (Not as good as the one's your using)

I like it - but I must agree that the present avatar is pleasent on the eyes.

 

[NavLinear]

Well I can see this thread heading for the ditch

Didn't take long - did it? We're good - really good - at hijacking threads (aka thread crapping).

 

[Gibsonian]

Great teamwork guys. It's pretty exciting stuff for freaks like us that are into the ole PL's. Sure makes me damned glad I got stuck on these amps a long time ago, but I sure never expected this!

Am interested in hearing more of sound and measurement comparisons between C and D. Also, is this going to eventually lead to Series 1's being capable of converting to fully complementary circuit? Is that what I heard? (I mean read). Also would be nice to know what components (and their values) that can be changed on C series to get as close to D as possible.

Thanks again Joe/Lee!

 

[fitz43]

Am interested in hearing more of sound and measurement comparisons between C and D.

Ditto that. Seeing that I have 2 C's.

 

[Gepetto]

Hi guys, the relevant changes for the RevD board that are possible to change on the RevC board are as follows:

1. R62L and R62R from 390 ohms to 270 ohms, Mouser part # 271-270-RC. Improves the adjustability of the bias pot in most amps.
2. C20L and C20R from 0.01uF to 1uF/63V, Mouser part # 505-MKS21.0/63/5. Improves the lower end frequency response flatness by doing a better job countering the ESR of C6.
3. C8L, C8R, C9L, C9R from 0.047uF to 0.15uF/100V, Mouser part # 505-MKP20.15/100/5. Slows down the bias changes with change in output signal level, making the bias current more consistent with loading.

The other changes are to enable future use of the RevD board to replace the very late editions of the Series 2 amps with full complementary output stages in them. We were getting requests for this from full comp Series 2 owners that could not be addressed with the RevC board. This has not been accomplished yet so the RevD is only being offered with the quasi-comp Bill of Material at this time and will remain the case until this new configuration has been fully tested.

Let me know if any additional questions.

Joe

The complete release notes for RevD are below:

Release notes for PL14_PL20 RevD PCB

1. Move silkscreen legend for R23R that was clashing with Q10R silkscreen.
2. Eliminate unused option resistors and diodes to free up space for additional changes. Components removed from RevC are: R70L,R70R, R71L, R71R, R72L, R72R, R78L, R78R, R79L, R79R, D3L, D14L, D14R (note some of these reference designators are reused in different applications on the RevD PCB, R70L, R70R, R71L, R71R)
3. Change lead spacing for C1L, C1R, C7L, C7R, C10L, C10R to more appropriately match the 0.234” spacing on mica CM05/CD15 type capacitors.
4. Enlarge pads on all mica and film caps to improve board durability.
5. Move components farther away from Q6 bias transistor connections to allow installation of the Phoenix Contact connector on the back side without hitting other pads.
6. Change Q3L and Q3R to MPSA92 and make circuit symmetrical with Q4L and Q4R for better behavior during turn on and off as well as bandwidth improvement. Provision for original 2N5087 circuit is retained with a resistor population option on the board. Added new heatsink requirement for Q3 same as the one used on Q4 in previous versions
7. Provide connection from Q3L/R collector through R78L/R to the B- rail to improve the symmetric current drain on the B+/B- rails. This improves power supply load symmetry and ensures that both supplies power on and decay at very similar rates, improving turn on and off control.
8. Increase the value of C8L/R and C9L/R to improve stability of the bias voltage during active operation. C8L, C8R, C9L, C9R from 0.047uF to 0.15uF/100V, Mouser part # 505-MKP20.15/100/5. Slows down the bias changes with change in output signal level, making the bias current more consistent with loading.
9. Increase the value of C20L/R to better offset the ESR of C6 and provide more consistent and flat response at higher frequencies. C20L and C20R from 0.01uF to 1uF/63V, Mouser part # 505-MKS21.0/63/5. Improves the frequency response flatness by doing a better job countering the ESR of C6.
10. Change vertical mounting hole spacing from 4.0625” to 4.00” to match actual PL chassis mounting hole spacing.
11. Add new lower edge I/O pad to allow use of the RevD board to replace the original PL36 board version in the fully complementary versions of the PL400/PL700 Series 2 amplifier (the last PL36 board artwork added these extra pins). Resistor options and wiring options now enable the RevD board to be used in this application.
12. Increased space around C23L and C23R to allow the use of the same capacitor as C3L and C3R in all locations.
13. Added C21L and C21R as lead network across R15L and R15R in the global feedback path.
14. Added C22L and C22R as Miller capacitors across the collector-base junction of Q5 to tailor/optimize the gain bandwidth and slew rate of Q5.
15. Added R78L, 79L, R78R and R79R in series with the collector of Q7L and Q7R respectively to provision for RevD board use in the complementary configuration.
16. Create new library pad stack for R20L and R20R to properly show the action of the trimmer with respect to CW rotation. The symbol showed CCW rotation on prior revisions.
17. Move connection pads 16L, 17L, 16R and 17R out from underneath C11L, C11R, R77L and R77R respectively to allow simultaneous access to both the static and dynamic bootstrap boost features.
18. Move lower edge connection pad silkscreen numbering upward to increase visibility when Phoenix Contact connectors are installed.
19. Overall, improved upon the already high quality of the RevC board in the creation of the RevD artwork by making small moves of components to improve assembly clearances, shorten and widen traces, increase trace clearances and improve signal integrity to maximize audio quality.
20. Change the value of R62L/R to provide better centering of the bias timmer on most amps. R62L and R62R from 390 ohms to 270 ohms, Mouser part # 271-270-RC. Improves the adjustability of the bias pot in most amps.

Release Notes Revision G
White Oak Audio Design Proprietary Information

 

[Gibsonian]

Thanks for the possibe C rev change details Joe.

 

[laatsch55]

Yeah Scott, damn good at that ain't he??


But WAIT!! THERE'S more!!

 

[laatsch55]

Ditto that. Seeing that I have 2 C's.

Doug, if you changed components as Joe suggested AND went with the new figures for R38,39 and kicked the bias to 510, AND went with the new Zoebel components, that would be damn close to what a full "D" wqould sound like.
Anybody got the new oebel figures??

 

[Gibsonian]

Doug, if you changed components as Joe suggested AND went with the new figures for R38,39 and kicked the bias to 510, AND went with the new Zoebel components, that would be damn close to what a full "D" wqould sound like.
Anybody got the new oebel figures??

No sir I do not. Said info on R38/39 and new zoebel components would be good to have for us C users.

More comments on the "D" sound also would be most appreciated.

 

[Gepetto]

Yeah Scott, damn good at that ain't he??


But WAIT!! THERE'S more!!

We will throw in the Ginsu knives...

 

[laatsch55]

LMOAO!!

 

[laatsch55]

Gotta go start a sub, went down on "low loss ride thru" and now won't start due to motor stall. Time for the shake and bake.

 

[Skratch]

Hi guys, the relevant changes for the RevD board that are possible to change on the RevC board are as follows:

1. R62L and R62R from 390 ohms to 270 ohms, Mouser part # 271-270-RC. Improves the adjustability of the bias pot in most amps.
2. C20L and C20R from 0.01uF to 1uF/63V, Mouser part # 505-MKS211.0/63/5. Improves the lower end frequency response flatness by doing a better job countering the ESR of C6.
3. C8L, C8R, C9L, C9R from 0.047uF to 0.15uF/100V, Mouser part # 505-MKP20.15/100/5. Slows down the bias changes with change in output signal level, making the bias current more consistent with loading.

The other changes are to enable future use of the RevD board to replace the very late editions of the Series 2 amps with full complementary output stages in them. We were getting requests for this from full comp Series 2 owners that could not be addressed with the RevC board. This has not been accomplished yet so the RevD is only being offered with the quasi-comp Bill of Material at this time and will remain the case until this new configuration has been fully tested.

Let me know if any additional questions.

Joe

The complete release notes for RevD are below:

Release notes for PL14_PL20 RevD PCB

1. Move silkscreen legend for R23R that was clashing with Q10R silkscreen.
2. Eliminate unused option resistors and diodes to free up space for additional changes. Components removed from RevC are: R70L,R70R, R71L, R71R, R72L, R72R, R78L, R78R, R79L, R79R, D3L, D14L, D14R (note some of these reference designators are reused in different applications on the RevD PCB, R70L, R70R, R71L, R71R)
3. Change lead spacing for C1L, C1R, C7L, C7R, C10L, C10R to more appropriately match the 0.234†spacing on mica CM05/CD15 type capacitors.
4. Enlarge pads on all mica and film caps to improve board durability.
5. Move components farther away from Q6 bias transistor connections to allow installation of the Phoenix Contact connector on the back side without hitting other pads.
6. Change Q3L and Q3R to MPSA92 and make circuit symmetrical with Q4L and Q4R for better behavior during turn on and off as well as bandwidth improvement. Provision for original 2N5087 circuit is retained with a resistor population option on the board. Added new heatsink requirement for Q3 same as the one used on Q4 in previous versions
7. Provide connection from Q3L/R collector through R78L/R to the B- rail to improve the symmetric current drain on the B+/B- rails. This improves power supply load symmetry and ensures that both supplies power on and decay at very similar rates, improving turn on and off control.
8. Increase the value of C8L/R and C9L/R to improve stability of the bias voltage during active operation. C8L, C8R, C9L, C9R from 0.047uF to 0.15uF/100V, Mouser part # 505-MKP20.15/100/5. Slows down the bias changes with change in output signal level, making the bias current more consistent with loading.
9. Increase the value of C20L/R to better offset the ESR of C6 and provide more consistent and flat response at higher frequencies. C20L and C20R from 0.01uF to 1uF/63V, Mouser part # 505-MKS211.0/63/5. Improves the lower end frequency response flatness by doing a better job countering the ESR of C6.
10. Change vertical mounting hole spacing from 4.0625†to 4.00†to match actual PL chassis mounting hole spacing.
11. Add new lower edge I/O pad to allow use of the RevD board to replace the original PL36 board version in the fully complementary versions of the PL400/PL700 Series 2 amplifier (the last PL36 board artwork added these extra pins). Resistor options and wiring options now enable the RevD board to be used in this application.
12. Increased space around C23L and C23R to allow the use of the same capacitor as C3L and C3R in all locations.
13. Added C21L and C21R as lead network across R15L and R15R in the global feedback path.
14. Added C22L and C22R as Miller capacitors across the collector-base junction of Q5 to tailor/optimize the gain bandwidth and slew rate of Q5.
15. Added R78L, 79L, R78R and R79R in series with the collector of Q7L and Q7R respectively to provision for RevD board use in the complementary configuration.
16. Create new library pad stack for R20L and R20R to properly show the action of the trimmer with respect to CW rotation. The symbol showed CCW rotation on prior revisions.
17. Move connection pads 16L, 17L, 16R and 17R out from underneath C11L, C11R, R77L and R77R respectively to allow simultaneous access to both the static and dynamic bootstrap boost features.
18. Move lower edge connection pad silkscreen numbering upward to increase visibility when Phoenix Contact connectors are installed.
19. Overall, improved upon the already high quality of the RevC board in the creation of the RevD artwork by making small moves of components to improve assembly clearances, shorten and widen traces, increase trace clearances and improve signal integrity to maximize audio quality.
20. Change the value of R62L/R to provide better centering of the bias timmer on most amps. R62L and R62R from 390 ohms to 270 ohms, Mouser part # 271-270-RC. Improves the adjustability of the bias pot in most amps.

Release Notes Revision G
White Oak Audio Design Proprietary Information

Is the 1uf cap part # suppose to be 505-mks21.0/63/5 I looked up part# 505-mks211.0/63/5 and nothing comes up?

 

[Gepetto]

Hi Mark
Yes it is the MKS21.0/63/5 Sorry for the fat finger.

 

[Gepetto]

Fixed the original post.