There is a lacquer called Incrylac or something close to that, that keeps copper based metals unoxidized, although regular lacquer works for a while..
3rd day work of my friend
To be continuous.....
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
To be continuous.....
After listern to O2 for a few days, I would like to write more about my feeling on it. This time, I want to compare the performance O2 to the AMP I am using (a DIY AMP made by me, and I call it HM-1).
Just share my work, HM-1.
The first impression of listerning O2 is, 'power' of it is enough, it can drive ER4S and HD600. But when compare with the performance of HM-1, for me, performance of ER4S and HD600 is better when using HM-1, and the sound details is more in HM-1.
However, it is not fair to compare O2 with HM-1. Because I am using 33.6V on HM-1, and the IC used is much more expensive. Once again, O2 is a very good AMP, performance of it is much much better than the AMP in same price level. It is not difficult to build such a wonderful AMP, everyone can enjoy it, especially for the newbie on DIY AMP.
P.S. O2 is quite hit in Hong Kong now, many people want to build their own O2.
Just share my work, HM-1.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
The first impression of listerning O2 is, 'power' of it is enough, it can drive ER4S and HD600. But when compare with the performance of HM-1, for me, performance of ER4S and HD600 is better when using HM-1, and the sound details is more in HM-1.
However, it is not fair to compare O2 with HM-1. Because I am using 33.6V on HM-1, and the IC used is much more expensive. Once again, O2 is a very good AMP, performance of it is much much better than the AMP in same price level. It is not difficult to build such a wonderful AMP, everyone can enjoy it, especially for the newbie on DIY AMP.
P.S. O2 is quite hit in Hong Kong now, many people want to build their own O2.
A fairly complete review of the O2 has been published by a former Mini3 and Schiit Audio Asgard owner. He rather liked it with all his headphones. His main criticism is it's too big to "wear" on your person (which unless perhaps you're wearing a winter coat I have to agree with). My idea of "portable" is something to have in my backpack for travel, airports, the cafe, backyard, park, etc. His review (sorry for linking to Head-Fi):
NwAvGuy's O2 DIY Amplifier
NwAvGuy's O2 DIY Amplifier
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RocketScientist, do you think there would be any issue with socketing the gain resistors? I was thinking of doing that for the people I am building for, so that they could change the gain at a later date depending on the headphones they are using. Using individual pin sockets would only raise the resistors up 2-3 mm..
MrSlim, that's an interesting idea for an optional upgrade.
As long as the pins will fit the 28 mill holes in the board, and grip the fine gauge 1/8 resistor leads, it would probably be OK. I've put some 1/4 watt values in vertically during prototyping and didn't see any notable change in performance. If any of those four resistors goes open circuit due to a bad connection, the O2 just drops to 1X gain.
If you have a Mouser part in mind for the pins, please share the part number and I'll throw some on my next order and check it out.
As long as the pins will fit the 28 mill holes in the board, and grip the fine gauge 1/8 resistor leads, it would probably be OK. I've put some 1/4 watt values in vertically during prototyping and didn't see any notable change in performance. If any of those four resistors goes open circuit due to a bad connection, the O2 just drops to 1X gain.
If you have a Mouser part in mind for the pins, please share the part number and I'll throw some on my next order and check it out.
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Sockets like this? 510-AG90D-10 TE Connectivity / AMP IC & Component Sockets
looks like you could break the strip apart and use the pins where you need them. Its also nice that if the resisters ever do fall out, the O2 will fail to a safe multiplier.
@sebash I can't seem to find a data sheet for that one. The mouser link goes to a product page and there are no drawings, etc. listed (but I might be blind).
There is a data sheet to Mouser part 535-10-0518-10 and it's specifically designed to be cuttable and says it accepts leads down to 0.015 in. The resistors are 0.016 so that should just work. I'll order one with my next order and check it out.
The no-solder solution is especially a good thing if the board is pre-assembled, as MrSlim is offering. Many of his buyers may not even own a soldering iron. But, if it works well, it makes experimenting with various gains much easier for anyone.
@MrSlim, were you planning on including a few extra gain resistors?
In my testing I can't say the expensive Mil Spec RN50 resistors have any real advantage to justify their higher cost. Even at 7X gain there's less than 1 dB difference in the noise performance (they are about 0.8 dB quieter but it's debatable if I can trust the dScope and my test set up to that sort of resolution when you're trying to measure a 3 uV signal to sub 1 dB accuracy.). At 12X they might be worth it but I haven't checked.
So I'm reworking the BOM to make the mil spec resistors optional to save everyone some money. They're also not RoHS compliant (lead free).
There is a data sheet to Mouser part 535-10-0518-10 and it's specifically designed to be cuttable and says it accepts leads down to 0.015 in. The resistors are 0.016 so that should just work. I'll order one with my next order and check it out.
The no-solder solution is especially a good thing if the board is pre-assembled, as MrSlim is offering. Many of his buyers may not even own a soldering iron. But, if it works well, it makes experimenting with various gains much easier for anyone.
@MrSlim, were you planning on including a few extra gain resistors?
In my testing I can't say the expensive Mil Spec RN50 resistors have any real advantage to justify their higher cost. Even at 7X gain there's less than 1 dB difference in the noise performance (they are about 0.8 dB quieter but it's debatable if I can trust the dScope and my test set up to that sort of resolution when you're trying to measure a 3 uV signal to sub 1 dB accuracy.). At 12X they might be worth it but I haven't checked.
So I'm reworking the BOM to make the mil spec resistors optional to save everyone some money. They're also not RoHS compliant (lead free).
@RocketScientist I can't find a data sheet for that one either but I dug a bit and found a page listing for the product line. It includes more information than whats on the direct link from mouser http://www.te.com/
Yes, after b0ck3n asked me if I would do custom gains, I figured why not put sockets in for them and provide some extra resistors to give them the flexibility.
The O2 Documentation Package has been revised. There's a new PDF, spreadsheet and the PC board files have been revised as well. This is hopefully the final version and what 200-some people will be receiving from the group buy and also the MrSlim builds.
The latest changes:
I don't think any of the above changes to the PCB are risky enough to delay things with a fourth prototype PCB. If anyone wants to look over the files, however, another set of eyes would be welcome
Hopefully the O2 is pretty much ready to leave the nest! The files, as always, are available here:
O2 Resources
The latest changes:
- The Parts List (BOM) has been substantially revised showing new alternate part numbers, correcting a few minor errors, and updating various costs.
- One hole on each of the positive battery terminals was made slightly larger.
- The MOSFET and IC regulator holes were made larger to allow all the specified part numbers to drop fully into the holes to stay within the maximum height for the enclosure.
- The top ground fill areas were sightly revised.
- The RF filter capacitor at the AC power jack has been removed
- R10 was moved slightly to provide more clearance for S1.
I don't think any of the above changes to the PCB are risky enough to delay things with a fourth prototype PCB. If anyone wants to look over the files, however, another set of eyes would be welcome
Hopefully the O2 is pretty much ready to leave the nest! The files, as always, are available here:
O2 Resources
I do not know if this is already mentioned. (not enough time to go through all the 22 pages). But is it possible to replace the input and output 3 pin (TRS) jacks with a 4 pin (TRRS) jacks? The 2e Ring should then go straight from output to input. This way you can keep using an iPod remote equiped headphone with the amp and just make yourself an 4 wire kabel from the iPod to the amp input. The remote signals and microphone would then be passed through by the amp.