The goal was to build a portable and durable amplifier with rechargable batteries. I chose a Rose-Bopla enclosure which isn't made for opening and closing so I had to do some thinking when it came to charging the batteries. The RJ12 jack allows me to charge the batteries with an ordinary 2x9V charger as well as power the amp externally with an extra batterypack or wall wart. The final unit is about 110x32x80mm and weighs about 340g, equivalent to a soda can. It doesn't have crossfeed yet, I think I can fit it above the META board but need the exact dimensions of it.

The some what poor quality pictures (click for larger pic):

Out of Focus wide shot:


Front:


Back open with Dongle disconnected:


The wiring of the RJ12 jack:


Case open:

Pretty slick looking. Only problem I see is some kid or imbucile trying to incorporate it into their telephone system!

That's a very nice case.. dare we ask how much it cost???

Very nice
How does it sound?

I just had the front off mine , so I measured the crossfeed board. It is 1 1/2" by 1 1/2".

Th case was approximately 55USD, It's a US brand so it should be a lot cheaper over there. It's made by Rose-Bopla and is Called Alubos 800. It's extruded aluminum with cast Al sides so it's easy to work with, all you need is a drill and a set of needle-files.

It sounds great, Been driving it off both computers and my Yamaha RX-V630RDS and it makes a lot of difference on my Porta Pros. I intend to get a pair of Etymotics ER-4P's and that's what it's mainly going to drive, adding a 75Ohm resistor in R9's position instead of modding the cable to get the S model, possibly with a switch.

If I do it will probably be another amp since I'm gonna have to find much smaller switches, preferably a Panasonic pot (anyone know where to source these in Europe?) and not use DIL-sockets for the resistors to save space above the board. I'd also move the 3.5mm plugs to the back and would probably have to find an alternative to the RJ12-connector, maybe RJ45 and find a way to use it for audio as well to save some space.


I'm also planning a maxed out META42 in a larger Alubos enclosure to feed off my HT-setup.

cj.9 thanks for the measurements, that should fit nicely above the board, problem is I have no idea where to fit the switches for it

Quote:



You could make it a permanent low-level crossfeed. Make it low enough in level that it doesn't hurt sound quality too much, but still helps with the hard left/right panning you get in some recordings.

cj.9's measurements aren't precise, but they're close enough. The actual board will differ from that by just a few tens of mils either way. One I just measured is 1.495 by 1.530 or so.

In that case, you'll want to use custom standoffs or no standoffs at all. Also, you may have to use polyester film box caps in order to fit them in that tight space; polypropylenes are probably too big.

I've considered that Tangent but since I've never done one before I'd like to be able to try some different settings. A DIL-socket might fit in there but I think I'm just gonna settle with this one for now and build a maxed out META when you release version 3. The enclosure also comes in 150mm and 200mm lenghts so an option is to buy a longer one and then cut it to length when everything is fitted.

Took some new pictures of the case and the chargercable. I had originally planned to solder the cable on to the chargers PCB but it would have been a pain to open the charger so I settled for a simpler solution. The cable just extends the battery poles out of the enclosure so I can charge them without opening it.

Click the thumbs for a larger picture:



Back:


Better overview :


Plugging it in to the telephone system won't hurt the amp atleast, pins 1 and 6 aren't used in swedish telephone system. I don't know how the system it self will react to being connected to 2 9V batteries though