[vidsan]

For creating an external battery pack to connect to the 4,5V plug -- how much can the voltage deviate? Will 4,8V be too much? 3,7V be too little? Are there other considerations I need to take into account? mAh? Should the mAh be as high as possible?
 
How do I modify the battery bay to paralell?
 
Another thing -- regarding the mods in this thread: Having only skimmed it, how much soldering must I have done and how much electronics knowledge do I need? Can I simply  follow the recipe and expect it to work?

 

[Student_Driver]

Quote:

Is anybody willing to sell their modded SRM-001 or mod mine? Thanks in advance...

I have the same question. Have the SRM-001 but don't use very much. Might like it better with the mod. Thanks.

 

[ecodoppler]

Hi AudioCats
I read with great interest your threads on Stax SRM-001headphones and I wish
to modify mine but there's a problem; I bought my Stax from Japan one years ago
but soon I noted a great distortion on the right channel. So I decided to send
the headphone to Japan  to repair it; after one month, I received
the stax but, again, I noted the same distortion. I complained to the Japanese dealer
about Stax Industry's behavior, but, obviuosly, I couldn't ship it again. Well,
the question is: by modifying the headphone following your suggestion, could I
solve the problem of the distortion and improve the sound as well?
thank you
Best Regards
Ecodoppler

 

[AudioCats]

 
ecodoppler, if the problem is indeed in the amp, the mod might not solve your problem. These mods are just parts upgrades, your amps might have bad output FETs, which is not touched in the above mods.
 
vidsan, if you are using a stock amp, anywhere between 3 and 6V will be ok. If you are using a modded amp the voltage should not be higher than 4.5V, or the Q15 can get hot really fast. Modding the battery bay to parallel is a major pain in the a, it is difficult to find room inside the case to add li-ion protection circuit board.
Soldering skill-wise, you need to be able to solder surfact mount IC's.
 
Is there a release date for the new amp yet?.

 

[spritzer]

Quote:

 
Is there a release date for the new amp yet?.

I haven't heard anything

 

[ecodoppler]

AudioCats
thank you for your explanation. And If I change the output FETs? At this point I cannot to ship again to Japan and I could give a try to this amplifier. What you propose?
Thank you
Ecodoppler

 

[pbandstefanwich]

What do you guys think about using a USB port as a power source? I believe it provides 5V and 500mA, but you could also string together two USB ports in parallel to get up to 1A like they do with some portable hard drives. Please correct me if I'm wrong, but I would assume it would be a cleaner power supply than most wall warts because it's coming from the DC laptop battery?
I think I am going to mod my Baby Stax and put it into a slightly larger case to allow room for some bigger batteries. How hard do you think it would be to work in a USB charging circuit so all you'd have to do to charge the batteries would be to plug your SRM into a USB port? If that won't provide enough power it might also be possible to work in a Firewire charging port, as I think that puts out 12V and up to 1.25A.

 

[vidsan]

@AudioCats: Thanks for the answer. I've bought normal rechargeable AA's, 2500 mA, and a pair gives me more than eight hours of continual use. Having an extra pair always at hand, running out of juice is no problem.
 
A question on static: My right speaker sometimes gives off a sort of crackling noise but then disappears. I am holding my right ear as a suspect as it is slightly larger than my left ear. Are there other possibilities? Warm-up time etc.?
 
Thirdly: I've shrink tubed the amp connector for more durability, but I'm still really worried I'll break the cable somehow. Is there a way to change the cables with something sturdier? Other DIY cable mods?

 

[rlmoss]

Google is increasingly useless, Search audiocats and it returns anything but your url. Search on audiocats.url and it returns youtube array. What is your url? One reviewer noted your mod of portable amp in former SR-001 better than one in SR-003 package. Big price bump from SR-001 to SR-003, quoted on Black Friday at $750
 
thanks,
 
Richard
 
rlmoss@penguinmail.com

 

[MrTom]

Quote:

Please correct me if I'm wrong, but I would assume it would be a cleaner power supply than most wall warts because it's coming from the DC laptop battery?

Hello,
 
I'm almost certain that the 5 V will not be wired directly from the battery as most laptop batteries are in the magnitude of 12-16 V. I'm guessing that it would be a DC-DC class D power supply due to the efficiency afforded and relatively low cost of implementation. If anyone knows any differently please say so as I'm interested!

 

[pbandstefanwich]

Quote:

Quote:

Please correct me if I'm wrong, but I would assume it would be a cleaner power supply than most wall warts because it's coming from the DC laptop battery?

Hello,
 
I'm almost certain that the 5 V will not be wired directly from the battery as most laptop batteries are in the magnitude of 12-16 V. I'm guessing that it would be a DC-DC class D power supply due to the efficiency afforded and relatively low cost of implementation. If anyone knows any differently please say so as I'm interested!

I'm not completely familiar with the class D rating, but after a brief google search it seems that class D use PWM and a high switching frequency to lower down the voltage. Is that correct? If that's really what they use in most laptops, then it certainly doesn't sound like a clean power source for this application! Is there an easy way to measure this or to measure how stable the USB power supply would be? i.e. if I hooked up a simple voltmeter to my USB ports, would I be able to detect fluctuations small enough to actually make a significant impact on the audio quality?
 
If most USB ports are actually PWM, then it probably wouldn't be suitable to run the amp directly off of the port, but it would be fine to use the USB to charge the batteries, correct? It would probably take longer than using a wall wart, but I think it would be a nice feature because of the convenience factor... instead of having to carry around a wall adapter when you travel you could just carry a simple USB cord that could also be used by many other devices you might have on you.

 

[ecodoppler]

AudiCats
I changed output Fets and Transistors but unfortunately I didn't solve the problem; after three minutes I hear an annoying distortion on the right channel. Do you think the replacement of the output Opamp could solve the problem?
Thank you
Ecodoppler

 

[AudioCats]

If the amp is stock, I don't think the opamp can cause problem, they are running at moderate voltage there is no reason for them to distore.
 
The only thing I can think of right now is to try another set of phones just to make sure the phones/cable are not the problem.

 

[kiromn]

Dear AudioCats,I have just made the FC class MOD and it sounds fantastic. The only issue is that i could not find the 0.1u 630V, so used only the stock output caps in paralel for this task. Can you recommend some replacement that can be found in stock? Conrad has WIMA caps, but there are several 0.1uf 630v available and i am not quite sure what is the difference.Thanks in advance and admirations for the hard work you have done, so all of us can do the mod.
 
 

 

[Robot Metal]

I have a broken SRM-001 here. The original owner apparently went over the volts it's supposed to take. Is it possible to fix it by replacing parts, and if so which ones? I'll dump money into mods, I just want to at least see it work first before any serious money gets put into it.