[borisov57]

Maybe someone has sr-001 headphone connector pinout?

 

[sclee]

We changed the opamp of the sr-001 amp to NE5532FE Philips ceramic, i thing i can direct solder a DIP8 on the PCB surface but it don't have enough room for do that, so that i solder the NE5532 and connect the other four pin by wire.

I changed the four power supply 10uf cap to 100uf Nichicon HD cap and shorted R33,R34,R35 i change the 1uf 50v C3 cap to BG PK.

When i first operated, i can not see any red or green LED light up, only listen the startup transformer sound.

I check all of the circuit and don't found any problem

i disassemble of R33 R34 R35, the green light up. We short those again and i work.

I also make a super cap box with 1 diode reduce the 4.5v power supply to 3.8v, 2x 10000uf Rubycon 16v and 1x ELNA AUDIO 3300uf 42v to provide the earphone power supply from a 400ma multi-usage AC-DC Adaptor.


The NE5332 provide more warm but also more detail of for all range sound. The bass enhance but thing that no texture. But no radio translate sound more.

After use the super cap box, the bass become more texture (some bass amount), and more detail provided. The speed and control had better that no cap, we can listen almost all detail of piano sound like sit in front of piano that i can not image SR-001 can do that.

Please caution that i close the system and not plug out the DC supply, it also have 630v electronic excite (

), it hit my heart

, so that any connect or test must plug out the DC power supply first.

 

[sclee]

Here is the photo of mod sr-001 amp and super cap box

 

[AudioCats]

the output Wima caps are of different size?

 

[sclee]

Quote:

Originally Posted by AudioCats /img/forum/go_quote.gif the output Wima caps are of different size?

The output wima both some value but wima have two different size, so that i use the small side on medium.

The blue one also wima 50v 3700pf bypass.


After i try install the super cap box, do not found any different between 400ma and 800ma dc adaptor, so that i just use the 400ma.

 

[AudioCats]

Quote:

Originally Posted by borisov57 /img/forum/go_quote.gif Maybe someone has sr-001 headphone connector pinout?

the plug: < -a-b-c-d-e-f- ]

a: not connected, serves as a switch so the amp will turn off when the cable is unplugged.

b: right side outter stator

c: right side inner stator (toward your ear)

d: left side inner stator (toward your ear)

e: bias

f: left outter stator



by the way, here is a failure mode of the 001 cable, I suspect it is the common type.(Thanks Catscratch for sending me this cable.) No broken wires, what happened was the bending actions at the plug weakened the silicon insulation, then the pulling (on the cable) caused the silicon to break at the weak point and exposed the copper wires. Since the signal is running at high voltage with little current, any moisture or dust or whatever can kind of short out the wires and cause an intermittern problem.

 

[sclee]

I replayed a pair of OPA2134 and found the current is 400ma
No heat generated from the opamp but i found most heat for this amp from high voltage.

The dynamic is better that NE5532, the speed is faster and the sound clearer that NE5532. But the bass amount of NE5532 is more that OPA2134, but may be the OPA2134 is new one and need some time for burn in.

The OPA2134 have more smooth high frequence response such as the saxphone is not hard.



Overall, i found OPA2134 is much better NE5532 when using in this amp.

 

[AudioCats]

Test 2, flea powered portable amp for driving full sized electrostatic phones:

So I was finally finishing recabling my ESP950 to silver/teflon/silicon, now the wire capacitance is about the same as the Stax ribbon cable's. Before putting on Neutrik 7-pin, I thought..... might as well try it on the 001 and see how it sounds.

In this test the 001 board has AD825 and Russian FT-3. Sound is loud enough, plenty of details, but not as juicy so not as realistic as the full sized amp. A bit cold and hard. Will let it run for a few hours and see if anything improves.

 

[borisov57]

Thank you AudioCats for pinout. I would like to roll my own amplifier for Staxes.

 

[AudioCats]

no problem borisov57, please let us know how your amp project goes. I assume it is also a battery-powered portable amp, right?

 

[borisov57]

No, I am thinking of full size home amp. I am very satisfied with sr-001mk2 for portable use. I used SR-80 for that purpose before, but staxes are completly different league for me.I will try amplifier with sr-001 because of absence of full size Staxes and funds for them. Of course, I will let you know, if it will be good.

 

[chi2]

Hi there!

I've got a SRM-001 MKII (since today early in the morning

) Great little beast! But it ate a pair of fresh alkalines in no time. That's why I tried some of my NIMH batteries. All of them have been freshly charged. The result leaves me puzzled: Of the six types of NIMH AA batteries only two are working; nonfunctional are among other Sanjo Eneloops and Duracells. The voltage is not different from those accepted by the baby Stax amp. Does anyone have an idea what causes the little amp to refuse some types of rechargable batteries while it happily accepts others?

Thank you, chi2.

 

[AudioCats]

it depends on how new your NiMh is. The NiMH deteriorates over time, the average acceptable service life is about 3 year, whether you use it or not (of course, it will get worse faster if you do use it).

When you measure the batteries, you measure them outside of the amp, no? that will be a no-load voltage. Once installed and turned on, the amp will ask for a bit of current and the battery voltage will drop. Even for the new batteries, 2x NiMH is already pretty low, if the battery is old the voltage can easily drop below the "no-go" line (when the amp is on) and the amp will give you the red light.....

 

[chi2]

AudioCats,

Thanks for your reply. Amazingly the never used Eneloops and the still very new Duracells don't work while some old Swissbatteries and a no name type work well. To complicate things even more, I found out that when mixing types of batteries (just to experiment - no standard practise

) things work if a certain type of battery is in the right bay, but it doesn't work when it's in the left bay. "Not working" actually means that none of the LEDs is on - also the red one stays dark. Could there be some sort a sensor that responds to the surface of the battery as those that are working seem to share a blank metal case??

 

[borisov57]

Hi chi2,

Did you bought new srm-001mk2 or used one? New ( unmodded unit ) should work for at least 4-6 hours. It draws cca. 300mA from batteries.