[Anaxilus]

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.

 

[violinvirtuoso]

Quote:

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.

 
Quote:

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.

As far as I can tell, FW Version 2.3 improves the HO and LO.

 

[ClieOS]

Very interesting test Soomal has done on T51 / S:flo2. For what I understand, DAP from big companies (i.e. iPod, Sansa, etc) tend to reserve a little headroom (usually by firmware) so the player won't clip at max volume or on EQ so easily.Teclast is probably a little too eager in the T51 project and forgot some of the fundamental in firmware design. Not a surprise consider software is always a weak spot for the Chinese DAP maker.
 
Quote:

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.

 

[Anaxilus]

Yeah setting my EQ to user and making it flat cut the LO output by about half.  That was my physical work around after noticing the distortion.

 

[Bananiq]

 
Quote:

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.

I am not sure about this, I've installed 2.3 black n blue few days ago (thru Vista with success), and the hissing screen still annoys me, but I do notice improved SQ. Thats very good news. Olso responsivity of touchscreen is better as was said.
 
btw: for some dark psytrance lovers, this track sounds soooo mindblowing on s:flo2, its in FLAC http://tinyurl.com/333gxr6 

 
btw2: does anybody received the leather case yet? 
 

 

[headfone]

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!

 

[Bananiq]

 
Quote:

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!

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
 
 
 
I have a question for those who know: Does the defective pixel on screen apply for a warranty?

 

[headfone]

 
Quote:

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

V. cool --- thx!
 
A few questions:
 
I've noted that loading files to S:flo2 is VERY slow. I'm using the supplied USB cable and assume it's 2.0. IAC, none of my other DAPs are this slow to upload. What gives?
 
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:
 
http://www.wolfsonmicro.com/products/dacs/WM8741/
 
It can go as high as 32-bit and has supposedly better filters. Speaking of which...modern DACs like WM allow one to control a lot of stuff via software. MP4Nation players (or any other serious DAPs) should allow advanced users (customers!!) to control the DAC (e.g. different DF settings, dithering, etc.) this way. This could be via a FW interface or directly thru the DAP in some sort of service menu (like Rockbox).

 

 

[headfone]

Quote:

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.

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.
 
** 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 (indentifying orch. instr. positions, etc)

 

[ClieOS]

Quote:

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:

NTFS is a Windows' thing. In fact, the 'NT' comes from Windows NT, which is where the file system is first used. It is not much an industry standard as FAT.
 
Also, though WM8741 and WM8740 is pin compatible, they are not actually fully compatible. They operates on different voltage and as well as support different features. This is without mentioning that the price of WM8741 is several times higher than WM8740. You can get a WM8740 on Newark / Farnell for about $5 but WM8741 is priced at $15. The improvement you get for the price difference on a portable player might not be that significant especially since it is not a very expensive player to begin with.

 
Quote:

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 ..

Just FYI, MP4Nation didn't engineer or design (beside the logo on the back) the s:flo2, Teclast did. Teclast sells it as T51 in China, and MP4Nation rebrands it as s:flo2 for the international market. Teclast did say that they have plan for T51 / s:flo2's successor, and hopefully with better firmware and compatible / better hardware. A side note, one of the reason why Teclast chose Philips' opamp for the HO is probably because Philips' opamp has been fairly well received in the Chinese DAP market in the past. You work what you think you can sell.

 

[borrego]

 
Quote:

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...

 

[headfone]

 
Quote:

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...

2132 "actually cheaper than" 2604? Where are you getting your price quotes, dude!? TI's site does a nice job of listing/tabling all the vendors and their prices....in any qty, it is the 2604 that is cheaper, and by a pretty big margin:
http://focus.ti.com/docs/prod/folders/print/opa2132.html
http://focus.ti.com/docs/prod/folders/print/opa2604.html
 
As far as the lower-limit rail power (e.g., 5V) for an opamp ... well, just because the datasheet specs that does not necessarily mean the opamp will (always) misbehave/clip/etc. if one drops below that magic minimum. You've gotta listen to/measure the device ... in the circuit. Also see Tangent's comment on this topic in one of my other threads:
http://www.head-fi.org/forum/thread/483097/running-pimeta-v1-or-v2-on-single-9v-cell#post_6560002
 
You're correct about this unit -- & pehaps all DAPs made by this vendor or outsourced designer -- being a confusing mixed bag of component choices, topology and overall design. As far as the too-low voltage issue, I'd add another in-series 3.7V (or other) Li-ion poly cell. Besides limiting opamp choices/uses, electronic upconversion is not a freebie ... it can get messy and NOISY.
 
Speaking of the opamp (and/or Teclast's general topological design philosophy) can someone enlighten me on the following (sorry: haven't yet had a chance to really dig into the S:flo2's PCB topology -- or topically search this forum's archives):
-- is the opamp class-A biased?
-- what brand/type/value are the SMD bypass caps (the ones off the PS pins of myriad ICs used)
--  what brand/type resistors are used (e.g. metal film by Vishay, carbon by Panasonic, et.c)

 

[borrego]

headfone. Sorry for incorrect information. The OPA2134 is cheaper than the OPA2604. Not the OPA2132.
 
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.

 

[headfone]

Quote:

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.

In what way specifically does the FW control PS logic?
Also, can the FW control Wolfson DAC's parameters? The wm8740 does offer software control of parameters informed users (ourselves!) would find useful. This includes different types of digital filtering (oversampling) and analog output polarity reversal (same as reverse phase: and important option all-too-often neglected in audio gear. The sonic detection is sometimes a hereditary thing (a some-can-some-can't-hear type deal) BUT the folks who can comprise  probably around 50% of listeners. Recording engineers sometimes use one or the other phases. Also, I think stuff (software/hardware) from Japan is always negative output phase polarity. I can hear phase and getting it right makes a big diff.; alas, one is at the mercy of the recording and/or all the other gear -- but having just one phase-correcting/controlling component in the chain would solve the problem.
No, I can't write FW code. Can anyone write the above DAC commands into the this DAP's FW...is this even possible with MP4/Teclast's core infrastructure?

 

[headfone]

 
Quote:

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.
 
** 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)

Okay, folks, it's official. Solid-state guru John Curl just said the AD825 is the best. So, Teclast/Mp4 designers ... add an option for using two single output opamps (the 825 comes as a single only). Does anyone know of a dual-to-single SMD/SO8 adapter that will fit in the flo2?