You're welcome.
The two BOMs differs for the composite opamp compensation.
The standard BOM uses the official My_Ref Fremen Edition compensation, which is very similar to the My_Evo (Evolution) original one.
Some time after releasing the My_Evo, Mauro Penasa (the original designer of the My_Ref) released an updated compensation for it, called Rev. A which offers improved performance and a sweeter sound.
That updated compensation is applicable also to the Fremen Edition with similar results.
From Penasa's My_Evo Rev. A document
- Improved stability on capacitive loads (the system now accepts the presence of any capacity directly at the output terminals without stability limits)
- Changing the decay of the damping factor versus frequency. The Rev A introduces more damping at medium and low frequencies.
- Change of the DC operating point active network integration. The high-pass third-order granted (Q> 0.7) is replaced with a previous "double-first order", or by an active integrator that works with the more classic high pass time constants next to the DC (> 0.1Hz) represented by the input coupling capacitor
- Change wiring of the chassis grounds ie chassis directly connected with the power ground sheet and no earth connection. (already recommended on FE build tutorial)
- Change of some wiring (pin 7 LM3886) (already implemented on FE boards)
An italian article which includes a My_Evo simplified schematic.
That article is published on the web by author, Claudio Negro.
That article is published on the web by author, Claudio Negro.
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All remaining boards shipped!
This morning I've shipped boards with SMD option.
No boards, apart one that will be collected and one delayed on request, left to be shipped.
All boards with SMD option have been populated according FE BOM, if you want to use the Evo Rev. A compensation one single SMD resistor must be desoldered (R39).
This morning I've shipped boards with SMD option.
No boards, apart one that will be collected and one delayed on request, left to be shipped.
All boards with SMD option have been populated according FE BOM, if you want to use the Evo Rev. A compensation one single SMD resistor must be desoldered (R39).
Important! (TH resistors orientation)
Until I update the tutorial with 1.5 and up images and notes one important thing.
When PCBs went to manifacturing R11 was a KOA MF1/4 resistor so on the PCB it's indicated orientation for that part.
In final BOM it's a Dale RN55, which have reversed orientation, so indication on PCBs for R11 is wrong, it should be mounted oriented this way (resistor is raised only to compare orientation):
Other resistors have correct orientation markings on PCBs since they were, initially, Dale PTF56 which have same orientation of RN55s.
Until I update the tutorial with 1.5 and up images and notes one important thing.
When PCBs went to manifacturing R11 was a KOA MF1/4 resistor so on the PCB it's indicated orientation for that part.
In final BOM it's a Dale RN55, which have reversed orientation, so indication on PCBs for R11 is wrong, it should be mounted oriented this way (resistor is raised only to compare orientation):
Other resistors have correct orientation markings on PCBs since they were, initially, Dale PTF56 which have same orientation of RN55s.
Attachments
No!the My_Ref RevA is the first version of the original My_Ref and it's inferior to the FE and the Evolution, all versions.
While the FE and Evolution are not identical a possible 'relation' would be:
My_Ref FE - My_Evo
My_Ref FE with Evo A mod - My_Evo Rev A
Problem with C9
Today I've finished my test build with the plain industrial BOM:
It obviously works perfectly but I've had the final confirmation that there's a problem with the Mouser cap for C9...
It sounds actually different from other KZs I've at home and that I used for BOM's tests.
In particular, after burn-in, it exhibit a strange midrange coloration which make it a bit too much laid back and with a larger than life soundstage, result is still good sounding but like you're in a room with excess reverb.
A tiny hint of that coloration was present also on the other KZs but not annoying at all, with Mouser part it's sadly different.
I'm sorry but I wouldn't expect such a different behaviour, I would suggest to use alternates in BOM like Black Gate STD & PK, Cerafines and Silmics Black/Gold (NOT Brown/White).
The amp sounds really good even with the KZ but when it's replaced by alternates the difference, and added enjoyment, is clear.
Today I've finished my test build with the plain industrial BOM:
It obviously works perfectly but I've had the final confirmation that there's a problem with the Mouser cap for C9...
It sounds actually different from other KZs I've at home and that I used for BOM's tests.
In particular, after burn-in, it exhibit a strange midrange coloration which make it a bit too much laid back and with a larger than life soundstage, result is still good sounding but like you're in a room with excess reverb.
A tiny hint of that coloration was present also on the other KZs but not annoying at all, with Mouser part it's sadly different.
I'm sorry but I wouldn't expect such a different behaviour, I would suggest to use alternates in BOM like Black Gate STD & PK, Cerafines and Silmics Black/Gold (NOT Brown/White).
The amp sounds really good even with the KZ but when it's replaced by alternates the difference, and added enjoyment, is clear.
Attachments
Temporary C9
I've updatad BOM and Mouser Projects with an alternate Mouser part, Nichicon ES which is colored too but without that 'bathroom' effect.
If mounted with the 'BP' side toward the LM3886 seem to work pretty nice.
I'll keep it mounted for the next days to fully burn-in the part, if it remains as is now it will be the new final Mouser cap for C9.
During the selection it has been the selected cap but was discarded since it has a slightly highlited midrange and KZ was more balanced (sigh!), now with the full burned-in KZ it's the contrary.
Please consider it temporary and if you didn't ordered already please wait a week, unless you already decided for an alternate C9.
I'll keep you informed, I'm really sorry about that....
BTW some good news now.
Only 6 hours on and a single IsoTek pass, without the KZ the new BOM works really well, really balanced, open sounding and sweet at the same time.
And it continue to improve so far, we'll see in the next days
I've updatad BOM and Mouser Projects with an alternate Mouser part, Nichicon ES which is colored too but without that 'bathroom' effect.
If mounted with the 'BP' side toward the LM3886 seem to work pretty nice.
I'll keep it mounted for the next days to fully burn-in the part, if it remains as is now it will be the new final Mouser cap for C9.
During the selection it has been the selected cap but was discarded since it has a slightly highlited midrange and KZ was more balanced (sigh!), now with the full burned-in KZ it's the contrary.
Please consider it temporary and if you didn't ordered already please wait a week, unless you already decided for an alternate C9.
I'll keep you informed, I'm really sorry about that....
BTW some good news now.
Only 6 hours on and a single IsoTek pass, without the KZ the new BOM works really well, really balanced, open sounding and sweet at the same time.
And it continue to improve so far, we'll see in the next days
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