[alphaman]

Confused .... other than burnwaygta4, who are all others (at player.ru and elsewhere) offering (or have offered) mods for T51/Sflo2? "AlexMod" was mentioned but I can't find a "home" link for his mod page. Also Strob, Hardcorist, w357? Who are all these modders ... are they still active?
 
Used shoppers should avoid early sFlo2's -- very unreliable. So buy used, not new-old-stock -- either they stopped working after a few mos. after new, or they were the improved QC version that seem to last!
 
Yes, the T51/sFlo2 is still competitive. Mine is 2.5yrs old and doing well. I modded it myself, but not extensively as it is delicate work. So... It's good that modders can offer services at modest cost. When one sees the $$ of top models -- AK, iBasso, etc. -- a modded CK4 or T51 is a very attractive alternative to the $$ "elite" units. Maybe better I was at CanJam, RMAF and CES ... so I got to compare ...

 

[Berkovajazz]

Quote:

are they still active?

Yes, they are, all in Russia, some new guys from Ukraine.
Also there are some new mods for iPod Videos/Minis, old Irivers and Cowons plus all top-tier players like iBasso, Colorfly, Hifimans, AK etc.
This guys have made some very good little amps and puts them inside players. Very good results.

 

[Migou67]

I look forward to the return of my T51 that is currently in the hands of BurnwayGTA, Is doing an amazing job 

 

[alphaman]

Quote:

I look forward to the return of my T51 that is currently in the hands of BurnwayGTA, Is doing an amazing job 

Well, w357, earlier in this thread posted some very detailed and extensive tips for DIYing this device. The Strob/Hardcorist project is very good, too, and you don't need many special tools to complete a project. You will learn a lot and have much more satisfaction in the end. Of course, everyone has different priorities and time constraints.
A word of caution: Like w357 notes, the T51 (and CK4, IME) are cheaply made and fragile. The T51 can be killed by little things like not grounding the liquid solder. Mods by anyone can result in unrecoverable disasters. 
I wish some one could come up with a way to use these DAPs as USB DACs.

 

[burnwaygta4]

Well, w357, earlier in this thread posted some very detailed and extensive tips for DIYing this device. The Strob/Hardcorist project is very good, too, and you don't need many special tools to complete a project. You will learn a lot and have much more satisfaction in the end. Of course, everyone has different priorities and time constraints.
A word of caution: Like w357 notes, the T51 (and CK4, IME) are cheaply made and fragile. The T51 can be killed by little things like not grounding the liquid solder. Mods by anyone can result in unrecoverable disasters. 
I wish some one could come up with a way to use these DAPs as USB DACs.

CK4+ has a very high quality PCB and does not die just like that.
opportunity to do a quality USB-DAC I do in my project for HM-601.

 

[alphaman]

Anyone know  the specific type of stock LPF  caps (in green frame in image below)...
 

 
They seem to be decent-quality plastic films (poly). I don't know what brand they are (some generic Chinese brand, I assume), but they look very similar to some high-quality Panasonic caps in my kit. 
 
 
EDIT: The orig. Teclast sales literature notes: "CBB polypropylene filter capacitor". This seem to be pretty good IME. Modders seem to be replacing with Wima. Yes, Wima are well know and respected. But IMO, they can soften sound too much also.
 
EDIT2: Earlier, w3357 suggested removing in-line R and C for kit of headphone amplifier (two resistors and two capacitors in pairs for each channel). Not sure why they are used but hopefully they are not part of DC blocking. Any aftermarket upgrades by modders should either block DC via high-qual. caps or use servo. Otherwise, your expensive headphone may be damaged by the fairly loud thump I hear when this device is turned on/off.

 

[alphaman]

Quote:

 
Replacement / differences from stock: 
[...]   capacitors in the LPF replacement for ceramic NP0
 

Unclear as to why putative lower-quality ceramics are being exchanged for original/stock (which are decent-quality poly/film, albeit low-cost Chinese variety and not Panasonic or WIMA). Or did you o'scope stock vs. NP0 and noted improvements? Also, did you change (tweak) cap values to match replacement OPA, as originals were ideal for OPA2604?

 

[burnwaygta4]

 
 
 
Quote:

Anyone know  the specific type of stock LPF  caps (in green frame in image below)...
 

 
They seem to be decent-quality plastic films (poly). I don't know what brand they are (some generic Chinese brand, I assume), but they look very similar to some high-quality Panasonic caps in my kit. 
 
 
EDIT: The orig. Teclast sales literature notes: "CBB polypropylene filter capacitor". This seem to be pretty good IME. Modders seem to be replacing with Wima. Yes, Wima are well know and respected. But IMO, they can soften sound too much also.
 
EDIT2: Earlier, w3357 suggested removing in-line R and C for kit of headphone amplifier (two resistors and two capacitors in pairs for each channel). Not sure why they are used but hopefully they are not part of DC blocking. Any aftermarket upgrades by modders should either block DC via high-qual. caps or use servo. Otherwise, your expensive headphone may be damaged by the fairly loud thump I hear when this device is turned on/off.

These are the Chinese low-quality PET condensers, because of them the sound very strongly loses in quality, it without problems is audible at their replacement by high-quality condensers, for example murata NP0.
That Wima FKS that Wima FKP - the best representatives in the classes therefore they also popular. ΣΔ DAC has big high frequency noise at output, in LPF it is necessary to use only NP0 ceramics (because of the very small parasitic inductance smd their contacts).
Teclsat t51 have no coupling cap because DC it is cleaned by differential LPF.
 

 

[burnwaygta4]

 
 
 
 
Quote:

Unclear as to why putative lower-quality ceramics are being exchanged for original/stock (which are decent-quality poly/film, albeit low-cost Chinese variety and not Panasonic or WIMA). Or did you o'scope stock vs. NP0 and noted improvements? Also, did you change (tweak) cap values to match replacement OPA, as originals were ideal for OPA2604?

I counted the Filter of Low Frequencies for more best sound.
NP0 ceramics now this best decision for a filtration ΣΔ DAC.
Read for example a cycle of articles from Cyril Bateman (http://ru.scribd.com/doc/2610442/capacitor-sound). Here some quotes:
 
Note however it is crucial to use only close tolerance and low distortion capacitors for both these positions. Preferred types
being 1% Foil/Polystyrene or COG disc ceramic.

Obviously a good C0G ceramic capacitor would work almost as well as my first choice of Polystyrene, provided the COG capacitor is available selected to 1% tolerance.

C0G From my tests it has almost no measurable harmonic distortion. COG ceramic is more stable with time and temperature than mica capacitors and from my tests COG can produce less distortion.

For 100 nF capacitance we find the lowest distortions are generated by choosing either C0G multilayer ceramic, metallised film PPS or PP.

For example COG ceramic is probably the most stable, and most nearly perfect of all commonly used dielectrics. COG disc and
multilayer ceramic capacitors do not rely on pressure contacts or metal spray connections onto their electrodes. One maker’s
products should measure consistently and with remarkably low distortion. Those from a different maker may measure slightly
 
Many articles have been written about capacitor behaviour, mostly by authors having little knowledge of capacitor design and construction. As a result, many popular but false capacitor myths have emerged:
a) All ceramic capacitors distort.
b) Dielectric absorption causes smearing and compresses dynamic range.
c) Polypropylene is an inefficient material.
d) Capacitors are highly inductive at audio frequencies.
e) ESR of a capacitor has a fixed value.
differently, but again should be consistent from batch to batch..
 
alphaman I think to you still it is necessary to be gathered knowledge before writing posts with such contents. Read more technical literature, instead of foreign subjective opinions.
 

 

[AlexRoma]

My TecMod (burnawayGTA mod) is finaly on the way back... 

 

[Migou67]

Still waiting for mine, please let us know how the sound improve when you receive it 

 

[Migou67]

You're a Wizard, time approach, thank you 

 

 

[alphaman]

I'm too lazy to Google these lazy questions about T51 and CK-4
 
Teclast T51 or Nationite SFlo2:
1. What's the native operating system for T51 (e.g., if Linux, which version)?  [enter answer]
2. What's the native disk file system for T51 (e.g., FAT32, etc.)?  [enter answer]
 
Colorfly CK4:
Same two questions as above.
1. [enter answer]
2. [enter answer]
 
 
Thx in advance!!

 

[alphaman]

Quote:

 
 
 
I counted the Filter of Low Frequencies for more best sound.
NP0 ceramics now this best decision for a filtration ΣΔ DAC.

The electrical engineers at Teclast (the designers of this device) are aware of the topological (in)abilities of passive components. And they correctly selected decent-quality Chinese-made plastic caps (the stock caps). NP0 ceramics --even by best manuf. -- are not superior. But the bottom line is economics: high-quality NP0 -- as the Murata you've selected -- are as cost-effective as  stock Chinese plastics. Yet the original designers correctly selected plastics.
One can understand a budding DIYer like you, burnwwaygta4, using these inexpensive DAPs as hobbyist platforms or as means to earn extra income. I personally don't agree with many of your claimed benefits or the unsubstantiated "technical literature" you refer to (but never fully reference).  

 

[burnwaygta4]

Quote:

The electrical engineers at Teclast (the designers of this device) are aware of the topological (in)abilities of passive components. And they correctly selected decent-quality Chinese-made plastic caps (the stock caps). NP0 ceramics --even by best manuf. -- are not superior. But the bottom line is economics: high-quality NP0 -- as the Murata you've selected -- are as cost-effective as  stock Chinese plastics. Yet the original designers correctly selected plastics.
One can understand a budding DIYer like you, burnwwaygta4, using these inexpensive DAPs as hobbyist platforms or as means to earn extra income. I personally don't agree with many of your claimed benefits or the unsubstantiated "technical literature" you refer to (but never fully reference).  

Think that you want, I about you already understood everything. Trust in what you want, me absolutely all the same.
Migou67 and Sefelt10 - i'll be waiting from you reviews of my modification.