Anaxilus
Headphoneus Supremus
- Joined
- Mar 12, 2010
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So does the new FW only alter the HO SQ? If the LO sounds the same from 2.2-->2.3 then I'll pass.
You can get all the customized T51/S:flo2 firmware from the Teclast user forum: http://www.teclast.com/bbs/forumdisplay.php?fid=7. People post their works at there first
With the V2.3, Teclast fixes the harmonic distortion caused by too high internal digitally controlled volume (from RK2806/WM8740 DAC chip) overdriving the OPA2604. The problem was first found by the Chinese review site Soomal: http://www.soomal.com/doc/20100001292.htm .
After finding the distortion probelm, Soomal declared the T51 was a s*#% player that Teclast should recall. It was quite an hot topic in the Chinese forums. V2.3 firmware is supposed to be Teclast's response to the Soomal accusation.
The first thing you'll notice after the V2.3 upgrade is the sound volume becomes lower, and you have to turn up the volume wheel a bit to get the same sound volume you got with V2.2. I perceived a bit less bass, with better treble, and a bit smoother sound and instrument positioning (less distortion?). Overall I like the improved sound.
The v2.3 firmware affects both the HO and LO. I also mostly listen through my Arrow through the LO so my comments on the "changes" were referring to LO.
You can get all the customized T51/S:flo2 firmware from the Teclast user forum: http://www.teclast.com/bbs/forumdisplay.php?fid=7. People post their works at there first
With the V2.3, Teclast fixes the harmonic distortion caused by too high internal digitally controlled volume (from RK2806/WM8740 DAC chip) overdriving the OPA2604. The problem was first found by the Chinese review site Soomal: http://www.soomal.com/doc/20100001292.htm .
After finding the distortion probelm, Soomal declared the T51 was a s*#% player that Teclast should recall. It was quite an hot topic in the Chinese forums. V2.3 firmware is supposed to be Teclast's response to the Soomal accusation.
The first thing you'll notice after the V2.3 upgrade is the sound volume becomes lower, and you have to turn up the volume wheel a bit to get the same sound volume you got with V2.2. I perceived a bit less bass, with better treble, and a bit smoother sound and instrument positioning (less distortion?). Overall I like the improved sound.
This issue is fixed in firmware version 2.3, it's not hissing either it is a slight crackling at the start and end of most tracks and probably happen during the tracks as well it is just covered by the music. Dithering may actually be what is happening here but it is hard to properly describe cause it is not just standard background noise.
My late-July-2010-built S:flo2 came with v2.2 so I would like to try 2.3. The links to 2.3 given above go to pages in Chinese lang. I don't know Chinese nor do I trust Google/other translate tools. IAC, I'm very careful about non-U.S. servers (sorry, nothing personal intended, but I've had my share of bad luck with sites from China, Russia, etc.).
What I would like is:
- a direct link 2.3 and/or other firmware
- clear instructions on how to install -- and (if needed) how to revert back to older FW version
Thx!
V. cool --- thx!Bananiq said:
fw 2.3 black n blue: http://narod.ru/disk/23368699000/Sflo2T51%20Theme%202.30%20firmware%20black%20n%20blue.rar.html
guide: http://www.mp4nation.net/forum/viewtopic.php?f=43&t=17834&p=188068#p188068
The problem with AD8620 is its minimum supply voltage is +-5V, which is higher than the S:flo2 can supply. May be the AD8622 is a better option?
The power supply of the S:flo2 is its another weaknesses. So I think the suitable opamp replacement will be another low power FET opamp like yours OPA2132 or the OPA1642.
One fellow in the Chines forum did swap in a LME49722 and claim getting excelent result. But I just won't believe the S:flo2 circuit is ready for any bipolar opamp with much greater input bias current.
I actually quite like the sound from the stock OPA2604. I think it keeps the best quality balance for listening low bit rate MP3 and FLAC/APE.
The native S:flo2 file fmt is FAT32, which is ancient and inefficient. Can one use (re-fmt to) NTFS (is this fmt even possible with the S:flo2?)?
Also noted newer, better Wolfson replacement wm8471 has been out for some time. It's pin compatible with wm8470, so a switch to this new/improved model would be wise choice:
What are the battery metrics (voltage, pwr, maH) for the S:flo2? I find it difficult to believe that MP4Nation engineers chose to operate the opamp at the min voltage ..
What are the battery metrics (voltage, pwr, maH) for the S:flo2?
According to what I read from the Chinese forums: The two 3.7V Li-ion batteries are connected in serial to give 7.4V, then voltage is up-converted to 10V (drops to around 9.5V after a few minutes of usage...), then go through a rail splitter to +-5V (+-4.7 V after a few minutes).
So your +-5V AD8620 will not get enough voltage before the 1st song has finished playing...
I am not sure about the mAh out. But I think swapping in any opamp which usea less mA than the OPA2604 should be fine.
I puzzle why Teclast would go through all the troubles to run dual WM8740 (using the reference Wolfson circuit), and voltage upcoversion (the main cause of the T51/S:flo2's short battery life) just to use the OPA2604. It would be much simplier to use just 1 WM8740 (or WM8741) and 1 OPA2134/32. The circuit will be simplier (no voltage upcoversion) and cheaper (OPA2132 is actually cheaper than OPA2604) to make. Someone in Teclast must love how the OPA2604 sounds running at +-4.7V...
I don't think you can do much further than opamp and capacitor mods with the S:flo2. The firmware itself has some control over the power supply logic. Unless you can rewrite the firmware, you cannot do modify the power supply parts.
What are the battery metrics (voltage, pwr, maH) for the S:flo2? I find it difficult to believe that MP4Nation engineers chose to operate the opamp at the min voltage -- I mean 5V is NUTS for an opamp in an audiophile product. Many opamps are at their best toward their MAX voltage range.
You noted bipolars ... carefully implemented LM6171/2's do well in portable audio gear I've DIY'd. As far as JFETs, my fave is AD825 and would pretty much chuck any other opamp model (regardless of $) to solder-in one of these guys (** see below). It's a single so you need 2 (anyone know of a very low-profile & compact 2-to-1 SMD opamp adapter that'd work in the S:flo2?). The 825 is a bit of a power hog, so more-frequent recharges will, alas, be needed.
Â
** AD825 pro: pace, rhythm, timing dynamics, bass slam, smooth midrange
AD825 con: lacks detail and acoustic-image focus
The AD825 pros easily, IMHO, make it the best opamp for portables/automotive: you need a sense of "driving pace" and rhythm while biking, jogging/walking, driving. The noted 825 cons are an acceptable compromise in the portable environment; e.g., while biking/driving, one is usually not concentrating on acoustic-image focus (identifying orch. instr. positions, etc)