The Objective2 (O2) Headphone Amp DIY Project

[lorriman]

Well blow me down and knock me over....

[lorriman]

I've been shock-proofing my O2. There's no give so if it dropped on to something hard then there is a real risk of damage, such as fracture, perhaps, of solder.

I filed down the edges and put electrical tape as the soft zone on each of the four edges. I've only put a little on front and back as there is limited usable space. Filing down also means that were one to do the double battery arrangement, as in the previous photo, then there will be space for a little anti-shock foam (or whatever material) on the top the the highest battery.

The ODAC also has a piece of cardboard on top of the coil filter as well as a large piece keeping it in place at the rear. I'm considering filing down some of the ODAC pcb as the USB jack area is too tight for anti-shock, and lead-free solder is even more delicate so I think it's a necessary adjustment.

(marvellously, I dropped the O2 on to stone just after doing this. The ODAC was already installed, but the force was lateral and merely moved the ODAC out of alignment).

[swalter]

Originally Posted by lorriman

Can someone remind me how many cells these batteries need. I remember that some aren't suitable due to too few or too many cells.

here the excerpt from NwAvGuy's Blog:
"TYPE OF BATTERIES - The O2 is intended to use Ni-MH “9 volt” (usually 8.4 volt rated) batteries. The Tenergy 8.4V batteries in the parts list are about 9.5 volts when fully charged and have 7 cells inside. There are also 6 cell (7.2 volt) and 8 cell (9.6 volt) batteries. While the 6 and 8 cell versions will sort of work, they’re not recommended. Alternately, you can also use disposable 9 volt alkaline batteries as you would in a Cmoy. Do not connect the AC power with Alkaline batteries installed (they’re not rechargeable)."

[Rockstar0215]

A lot of mouser parts are on backorder for the o2. I don't think I can wait till October...

[fenderf4i]

Check Digikey for the remaining parts. Here in Canada it only cost $8 shipping from Digikey for the remaining parts that I needed to finish a build.

[fenderf4i]

Oh, Digikey also has the nicer knobs if you're placing an order with them. ML-50-4-6MM Kilo International | 226-4003-ND | DigiKey

[digitfan]

Built into a Black Cube clone case.




The O2 board was piggy-backed on the Black Cube clone pcb, which is exactly the same width. The battery-related parts, gain switch, input/output sockets, LED, and volume control were left off the O2 board and wired up as required.

The original O2 volume control was replaced by a new Alps 10KAx2, and the output socket by two new gold-plated Neutrik ones. The O2 on/off switch was left in place and is operated via an extender through a new hole drilled in the front panel just above the LED.

There's an input switch at the back to select between the ODAC and one pair of rear phono sockets, the other pair of phono sockets being connected to the left-hand headphone socket to act as a switched output, as in the original (?) clone.

AC comes in from a socket at the rear via a short length of USB cable, with the cable screen grounded at the front end.

[Rockstar0215]

Originally Posted by fenderf4i

Oh, Digikey also has the nicer knobs if you're placing an order with them. ML-50-4-6MM Kilo International | 226-4003-ND | DigiKey

They definitely do have the better knobs. It still doesn't solve my problem because Digikey doesnt have Lelon capacitors...that's the part that has the longest backorder.

I would hate to place an order in 3 different places, shipping can get expensive for one part or two.

[swalter]

Originally Posted by Rockstar0215

I would hate to place an order in 3 different places, shipping can get expensive for one part or two.

Likewise. There are plenty of alternatives listed in the BOM: Nichicon UVR1V471MPD1, Epcos B41827A7477M000, Panasonic, EEU-FR1V471B, ECA-1VM471B
Else you could get the whole lot from me

Stefan

[brickj]

pby - thanks for the battery recommendation, I'll give them a try.

The Tenergy batteries don't seem readily available in the UK, hence the quest for alternatives (that fit, without interfering with the case.)