HL-DT-ST BD-RE BH40N - Slow UHD Read Speed

[theflock]

Hey everyone,

I've been testing an internal desktop LG drive and wanted to share some data points and ask for some guidance on cross-flashing.

I have an HL-DT-ST BD-RE BH40N running stock firmware A1B0 (MT1959 platform). Interestingly, MakeMKV reports that LibreDrive is fully enabled out of the box on this stock firmware, and it successfully reads 4K UHD discs.

However, when ripping or reading the UHD disc, the speed is locked right around 2.0x (~8.9 MB/s), accompanied by occasional L-EC uncorrectable read errors on certain offsets.

Here is my drive info block:

Plaintext
Drive Information
OS device name: G:
Current profile: BD-ROM
Manufacturer: HL-DT-ST
Product: BD-RE BH40N
Revision: A1B0
Serial number: SIK93G38J391
Firmware date: 2115-10-13 14:46
Bus encryption flags: 1F
Highest AACS version: 82

LibreDrive Information
Status: Enabled
Drive platform: MT1959
Firmware type: Original (unpatched)
Firmware version: 0.A1B0D
DVD all regions: Yes
BD raw data read: Yes
BD raw metadata read: Yes
Unrestricted read speed: Yes

Disc Information
Label: INDIANAJONES_LAST_CRUSADE
Timestamp: 2021-03-30 19:08:29
Protection: AACS2.0/C v76
Data capacity: 60.19 Gb
Disc type: BD-ROM UHD
Number of layers: 2
Bus encryption flags: 80

Even though LibreDrive status shows "Unrestricted read speed: Yes", the drive refuses to ramp past 2.0x on UHD layers.

I'm considering cross-flashing this desktop drive to unlock proper performance, but I want to make sure I use the right path.

Which exact firmware version/variant should I target for this MT1959 BH40N drive? (I've seen mentions of WH16NS60 variants, but want to confirm the safest/best build to use).

Is this 2.0x cap a limitation baked into the stock A1B0 microcode that a cross-flash will successfully resolve, or is this hardware just prone to throttling on UHD?

Appreciate any advice or flashing recommendations!

[zittrig]

Flash to WH16NS60 1.02MK. The ripping speed should increase.

[theflock]

I'll give that a shot, thanks.