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The Stax SRM-001 mod thread - Page 2

post #16 of 402

Additional Mod

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post #17 of 402
Hey Richter, I'd like to know more about your tip modding. Can you elaborate? Can we also see some pics of finished work? Thanks
post #18 of 402
Quote:
Originally Posted by antonyfirst View Post
Hey Richter, I'd like to know more about your tip modding. Can you elaborate? Can we also see some pics of finished work? Thanks
And, AudioCats, any further conclusions on what mods to complete that can improve SQ while retaining all in the original case?
post #19 of 402
Thread Starter 
webbie, if you install 8599, everything packs into the Stax case, no question about it. Guarranteed to succeed.

The AD825 on the other hand, is a little tricky, it requires much larger caps if you use an AC adaptor, can be done but not nearly as straight forward as the 8599 (for pure DC operations, see the updated post #2, the green text contains more info). But to install AD825's you will have to make a SOIC->SIP adaptor anyway, which is a major pain in the axxx (creating a PCB program for an adaptor is easy and I have the eagle lite, I just couldn't bring myself to do it).



plans:

I am doing the capacitor burn-in right now. The next step will be the input/output cap test. Then I will provide a list of things to do and parts to use. To-do list only, there won't be a complete pictorial step-by-step tutorial anymore. ( I don't want to encourage first time DIY'er to attemp the mods since there is the 550v voltage present. If you have a little DIY experience you should be able to just look at the to-do list and figure out the details by yourself).
Three performence levels, pick one depending on your budget and your signal source quality.
1) The Fat Cat -- BlackGate/polyprop as input, 8599, BC component as output, and using larger capacity aluminum electrolytic for +/- power.
2) The Super Fat Cat -- BlackGate/polyprop input, 8599, Sonic I or Sonic II as output, install BlackGates whereever possible.
3) The Fat Cat Ultra -- BlackGates/polyprop input, AD825's on adaptor strip, Auricap as output. Install BlackGates whereever possible.
(Due to the super revealing nature of the electrostatics, I wouldn't recommand a mod level higher than the Super Fat Cat if you are using MP3 as your source.)


Anyway, I don't know if you guys have ever read the updated 1st post in this thread, I have one slot open for a SFC (super fat cat) mod.... with conditions attached though

Have fun
post #20 of 402
Thread Starter 
FatCat class output cap results: (top to button: BC component MKP , Panasonic ECWF Polyprop, Stax stock poly cap, Epcos MKP).



-- The best in the group: BC components, MKP420 series, 0.011uF/630v, digikey # BC2240-ND, $0.61 each.
The sound: Smooth, no harshness, clear highs, best details so far, good mids, strong bass.

-- 2n place, Panasonic ECWF metalized polyprop, 0.01uF/630v, digikey # p12109-nd, $1.33 each.
the sound: good treble, slightly smoother than stock caps; warm mids; Strong bass, but lack definition, the bass is also dryer than the BC.

-- 3nd place: Epcos X2 series (not shown in the picture above). The digikey # for 0.01uf/630V: 495-2317-nd, $0.32 each.
The sound:I was using 0.1uF but would expect the 0.01uf have the same sonic charactoristic. Larger capacity gives more bass for larger phones (see the ESP950 experiment), but there is not much difference when pushing the baby stax. Anyway, there is a lot of bass, but mids and treble are very soft. After long burn-in they will get nicer, though still not quite as sharp as the Panasonics. But the X2's bass is not as dry, a little more pleasant to my ears. Over all, it is rated very close to the Panasonics, won in some area and losed in others. If you end up going for the AD823 or TL082 (for power consumption reasons), this will be the cap to use. It may also be used for covering up harsh/cold sources.

-4th place: stock stax 0.01uf/630v poly(ester?) and Epcos MKP 0.01uf (digikey#495-1326-nd, $0.51 each). These two are rated about the same with the Epcos MKP slightly better than Stax poly. Good clear highs but has some harshness (quite noticable with the stock cap, MKP is a bit smoother); good mids; bass lacks both definition and strength.

Above polyprops are all the possible (due to the size limitation) candidates from digikey. You might be able to find other caps from other venders that might fit but in my oppinion the BC component is pretty good already, plus.... well, they are all super cheap anyway. One bonus when using the Panasonics ECWF though, is that they are the shortest in the group (the Epcos MKP is as short but obviously you wouldn't want to use it), and allows two 0.1uf/630v X2 series high voltage power cap to stay on top, as seen in the picture below. These three 0.1uf X2 caps in the picture will provide 0.3uf for high voltage power reserve, about enough if you are not a bass head. (bass heads should try to add more caps elsewhere and try to reach 0.5uf or a little higher, but there is no need to push above 1uf).




Boutique output caps and input BlackGates are still being burnt-in, result will come out in about a week.

Stay tuned.
post #21 of 402
Thanks for the update, audiocats.

Definitely staying tuned - each episode keeps building up the excitement (anticipation)
post #22 of 402
Thanks for the update!
I am watching this thread closely. Cause if the result turn out to be a major improvement I might end up buying the SR-001MK2 again and get it modified.

Keep us posted!
post #23 of 402
Thread Starter 

Shoot-out, AC / DC

while the blackgates and Sonic caps are still being bombarded/tortured by friendly musical electrons, lets talk about power.... Obviously the best power source is large capacity pure DC ( ie battery banks), but AC adaptors are (or can be) still great for desktop use, since they just keep on going 24/7. The most commonly found/used AC adaptors are the Sony and Panasonic 4.5V discman wallwarts. Here is a review on the sonic difference between these wallwarts. We will also take a look at higher power options, ie. regulated power supply.

(Left to right: Sony 4.5V/500mA; Panasonic 4.5v/800mA; modified 5V/1A, originally for external zip drives)



Test configurations:
Everything in the SRM-001 is done like what will be in a FatCat class mod, except the input electrolytics are still 22uf tantalum (since the blackgates NX's are still being burnt in). C17/18 are using 220uf/16v miniature aluminum electrolytics, C26/27 are 47uf BlackGates PK miniature (you can also use the same 220uf/16 as in C17/18 position, I installed PK because I am out of 220uf miniatures). The results below will be what happen with these power sources driving a FatCat SRM-001 (SRM-001-FC?).

Now the shoot-out:

* Panasonic:
--in previous posts I have mentioned this wallwart gave a hum.... that was during minimun cap size testing, and with the AD825 installed. In the FatCat/SuperFatCat mod we use 220uf +/- caps and 8599, with this configuration there is basically no hum from any of the wallwarts.
--The sound: a little layback and distant; has a emphasis in mids therefore showes vocal charactoristic very well, especially if the voice is "raspy and gritty". Some minute details don't stand out very well, possibly due to the mids emphasis, this gives a false sense of "cleaner" sound when playing vocal tracks. Strong bass, good texture. The sound stage is the narrowest of the group.
-- measures 4.61V under load.

*Sony:
-- the first thing you will notice is the sound is Soft. Showes details better than the Panasonic, larger sound stage. Bass is a little drier, and not showing bass texture very well. Kind of strange, all the details are there, but I sense a layer of haze.....
-- measures 4.67V under load.

*Modified 5v/1A regulated zip wallwart.
-- the zip wallwart requires quite some modification, first of all you will have to change the plug to fit the SRM's jack. In my previous posts I have mentioned when the zip wallwart (before mod) was plugged in, the sound was good for the first 2 seconds then got very bad. I first thought the slightly higher voltage (5V vs. 4.6v) caused the SRM's inverter to act up, but latter thought it could be the inverter's pulse spikes going back into the wallwart and confused the regulator chip. Now it seems that the pulse spike is indeed the cause. After adding a CLC filtering circuit (regulator -> 2200uf cap -> small coil -> 4400uf cap ->output), the wallwart now works very well. The purpose of the filter stage is mainly to prevent the high frequency inverter pulse from reaching regulator. The 4400uf cap also acts as a power reservoir, it might not have to be that big, I put it in simply because I had one laying around and it would fit into the case.
-- The sound is analytical, well, kind of. Showes lots of details clearly, great bass thump(relatively speaking) and texture. It manage to show the sounds a lot better than the above two without letting you enjoy a lot more..... Strangly wide sound stage, almost speaker like (again, relatively speaking), the sound field is diffused and doesn't allow easy instrument pin-pointing.
-- voltage is 5.04V, regulated, same voltage loaded or not.

* DC! Lithium batteries, 2000mAH capacity.
-- I used two 14650 in parallel, they are older cell phone pack batteries so the capacity is only 2AH total. If you use the newest ultrafire 14500 (AA size, 900mAH each) you will get 1800mAH with two in parallel, the result should be the same as my test setup.
-- The batteries are about 3/4 full when tested, at 3.85V.
-- The cleanest sound so far, crispy and clear; intimate vocal, even better than the panasonic. It has the best bass thump, though the texture is slightly less "visible" than the modified zip wallwart. Sound stage wise is slightly larger than the Sony.

It really surprised me that the power source actually made this much difference, I used to think since there is a step-up inverter inside the SRM-001 (all the actual amp power come from the inverter), the wallwarts should work the same as long as they provide enough current.... how wrong I was.
Here is a summary of this power source comparison:
(in the order of best -> not so great)
*Bass thump: Lithium -> modified zip wallwart -> Panasonic -> Sony
*Bass texture: Modified zip wallwart -> lithium -> Panasonic -> Sony
*Vocal/mids: Lithium -> Panasonic -> Modified zip -> Sony
*Details (high/mids fineness): Lithium & modified zip -> Sony -> Panasonic
*Sound stage(wide -> narrow): Modified zip -> Lithium -> Sony -> Panasonic
*sound locating: Lithium -> Panasonic -> Sony -> modified zip

As we can see, the DC power is indeed the best overall, and the regulated high output power source doesn't necesary do that well. I have no idea why the Sony and Panasonic sound so different, they are just transformer/diodes/capacitor, unregulated output, both at 4.6V level...

The conclusion:
-- Pure DC is the best, get a bunch of 14500 lithium rechargable batteries and call it good
-- If you already have a wallwart of some kind and want to "upgrade" to a big-axx bench-top supply, well the expensive and super-stiff bench-tops might not give the best results with the SRM-001. Meanwhile, the smaller/lesser/more-cheaply-made regulated supplies might not work(or not as well as it could be) due to the inverter spike situation, some modification might be needed.... well, might as well inverst the benchtop PSU money for lithium rechargables and keep the wallwart for warm up purpose.
-- or, if you have tax return $$ burning holes in your pocket/wallet/purse, get a bunch of different 4.5v-5v power supplies and do the experiment yourself, one will work best for a certain type of music while the other one best for another genre. Panasonic will be good for vocal (only), while a regulate supply, with that much details and good bass and super wide diffused sound stage will be the best for trence..... kind of like keeping different headphones you see


(I can't believe I put down this much BS just on power sources, it was supposed to be a short review.... )
post #24 of 402
Great, I have the Sony 4.5v on the left, and nothing to use it with. My SR-001 Mk2 will arrive Wednesday!

I await your review of the differences. I also have a 5v wallwart that was for some Plantronics bluetooth earpiece for cell phones.

Do we have to cut the cable and switch the tip to negative center, since my SRD-X 1/4" uses a 12v negative tip I thought maybe all STAX uses negative tip ?

I also have a $90 regulated PS but it only does 12v-24v in 1v steps (4.5A), and doesn't go down to 4.5v. It does a great job with the SRD-X though.
post #25 of 402
Thread Starter 
Quote:
Originally Posted by HeadphoneAddict View Post
Do we have to cut the cable and switch the tip to negative center.
No! don't do it.....the SRM-001 power jack is the "normal" center + type, Panasonic and Sony 4.5v discman wallwarts will work as-is
post #26 of 402
I asked the question because "I never do before I do ask" as my grandaddy always said.

Or, as Forest Gump would say, "Stupid is as Stupid does", and that wont describe me
post #27 of 402
Quote:
* DC! Lithium batteries, 2000mAH capacity.
-- If you use the newest ultrafire 14500 (AA size, 900mAH each) you will get 1800mAH with two in parallel, the result should be the same as my test setup.
-- The batteries are about 3/4 full when tested, at 3.85V.
-- The cleanest sound so far, crispy and clear; intimate vocal, even better than the panasonic. It has the best bass thump, though the texture is slightly less "visible" than the modified zip wallwart. Sound stage wise is slightly larger than the Sony.
I also use 14500 Li-ion AA batteries in mine (only one at the time with a piece of copper as dummy, so you don't have to open the case ; Its a direct replacement)
I gives me a few hours of runtime and I am very happy with the sound ;much better than normal batteries or the AC power sources I have tried.

Audiocat: great topic you have here!
post #28 of 402
How many hours is "a few hours"?
post #29 of 402
Thank you for AudioCat tutorial,it a very useful.
I just new entry to sr-001 for few week, the module still burning, as i like to listen the change of burning.

Previously, i only want to use this on my travel on night at hotel, but after use i thing this can be compare as to or better to my using K701 system.

The speed quick and not noticeable delay, when i come back to K701, the speed is so slow and sound push out some time. The bass is more better that entry level elec. phone such as 3030 and 2020

I do not want to mod the unit so much, i study the amp, good design.
I want to improve the speed and detail of sr-001.

I like to change the 10uf 50v cap to Blackgate and paellel as a PP, i buy two 10uf 50v Blackgate N cap, but can not find good PP fitted on the room, because two BG is too big, so that i just use two BG and no PP.
That mean the cap uf had been increase 10uf vs (10+0.15)/2 =5.075uf. Normal the speed become slow and bass increase

But after i install and run few hour after, the speed is so great and faster that before about 50%. The bass is not much deep and open before, i know that should be burn at least 300 hr, as our K701 head amp BG output cap already run one year but also can listen the improve.

As i use a DC-AC selectable transformer with noise reduce function, i can not listen the noise even to the higher volume, i have 400ma and 800ma, a 800ma transformer have better bass detail and more deep.
post #30 of 402
Quote:
Originally Posted by sclee View Post
Thank you for AudioCat tutorial,it a very useful.
I just new entry to sr-001 for few week, the module still burning, as i like to listen the change of burning.

Previously, i only want to use this on my travel on night at hotel, but after use i thing this can be compare as to or better to my using K701 system.

The speed quick and not noticeable delay, when i come back to K701, the speed is so slow and sound push out some time. The bass is more better that entry level elec. phone such as 3030 and 2020

I do not want to mod the unit so much, i study the amp, good design.
I want to improve the speed and detail of sr-001.

I like to change the 10uf 50v cap to Blackgate and paellel as a PP, i buy two 10uf 50v Blackgate N cap, but can not find good PP fitted on the room, because two BG is too big, so that i just use two BG and no PP.
That mean the cap uf had been increase 10uf vs (10+0.15)/2 =5.075uf. Normal the speed become slow and bass increase

But after i install and run few hour after, the speed is so great and faster that before about 50%. The bass is not much deep and open before, i know that should be burn at least 300 hr, as our K701 head amp BG output cap already run one year but also can listen the improve.

As i use a DC-AC selectable transformer with noise reduce function, i can not listen the noise even to the higher volume, i have 400ma and 800ma, a 800ma transformer have better bass detail and more deep.
1st POST! Welcome to head-fi, and sorry about your wallet!
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