[threedee]

Bye bye my lovely Philips HD1505. It's been fun for three years. Day in, day out, sometimes all day long... etc...
Broke completely due to heavy use and pretty crap build quality. Didn't hold long term...
 
Here's my first impressions three years ago:
http://www.head-fi.org/forum/thread/288393/my-philips-sbc-hd1500u-impressions
 
So, i've been searching for somehing to replace wireless digital amp, didnt find anything.
And since i like to wash my car with quality sound on my head, decided to try something new:
Rip out innards from headphones themselves and make a standalone portable amp/receiver
into which i can plug anything i want. And transmitter being a DTS/DD/DH digital thing its nice,
it still works just fine, so does other end, if not for build quality...
 
Also busted one driver (on that later).
 
So, here's my big question: how do i proceed ?
Theory is easy - build a box to house two boards (60x60 and 50x55 mm). Control board has buttons
(power/volume/bass/trebble/tune) so has to stick out somehow. Also needs to be powered by 2 x AA
batteries, but i think i may want to increase that to 3 or 4 AAs, 2AAs net about 8-13+h of continuous
operation (depends on mAh).
 
I'm thinking perspex/plexiglass. Would look nice.
 
Need advice on tools and or methods used working plexi (joining, milling drilling etc...Wil not be bending
folding). What sort of tools will i need ? Glue or screws ? Etc.
 
Will be posting pics of the boards, bits and pieces shortly, if anyone is interested....
 
At this point i'm still at planning stage so any input/advices would be welcome.
It was a looooong time since i did something like this..... Should be fun...
 
#UPDATE1#
 
Went from this
 

 
to this
 

 
#UPDATE2#
 
Added photos of disassembly (or more precisely "assisted falling apart" )...
 
Album here (29 pics)
 
http://imgur.com/a/DkLA4#0jQbt
 
Also, please help me identify this 50mm driver used in these phones. No markings whatsoever...
 

 
 

 

[bcg27]

Very interesting project. I think it will be quite a challenge to fit an antenna, decoder, DAC, amp, and batteries in such a small amount of space but I look forward to seeing how you approach it. 

 

[threedee]

Done some preliminary CAD work for housing.
 
General diagram and board dawings (still missing correct thinckness, dont have vernier caliper to measure(its in a post somewhere now))
 

 
...And housing versions exploration. May try to 3D it later to see how it looks...
 

 
Also, how do i place antennae in the gousing ? Can i lay them parallel to each other ? Any interference considerations etc ? Someone with electronics background - feel free to butt in now

 

[bcg27]

It depends what kind of antenna they are, what frequency they operate at, what kind of modulation they are using...
 
Why are there two antennas?

 

[threedee]

According to http://www.dealersupport.se/imagebank/pdf/1233.pdf
863.3 to 864.5 mhz.
 
No idea why there are two antennae, however the stupidest thing in design of placement was to insert one
of them into one of the earphones housing, which flexes. It probably broke within months, because the wire is fairly thick (0.75-1mm?).
 
One antenna wraps around the plastic bit on radio board, the other one inserted into driver compartment and hot-glued there.
 
Check the gallery of photos, its all shown there. Fault as well.
 
 

 

[bcg27]

Hm, I suppose it could be that one is send and one is receive and they operate at different frequencies so they shouldn't interfere with each other much as long as they aren't touching (see iphone 4). Any way you can get a fairly accurate measure of the length of each of them?

 

[threedee]

I don't think it transmits anything back. There is no point to. Should be a passive receiver, like a radio, methinks.
Doesn't DD/DTS have some sort of error correction in the transmission already ? Plus, transmission is digital, not just FM.
Upon reaching transmission limit (too long distance) sound starts breaking up, but the quality doesnt degrade as in FM (there is no noise whatsoever)...
 
The one intact measires exactly 65mm.
 
#Edit1# Ah, it uses GFSK, which is what bluetooth uses as well... digital...

 

[bcg27]

65 mm seems a little short for a quarter wave antenna @ ~864 MHz. You are probably right about the passive receiver.  Unfortunately antenna design is not really my strong suit. Are you planning to use the existing receiver/transmitter and decoder? I haven't heard of DD or DTS being overly friendly to DIYers. They really like their licensing fees.

 

[threedee]

Well, the two thick wires are the most resembling antennae from all the parts i've seen come out of housings.
However, the 2 wires connecting both sides of headphone and electronics (one board on each ear) are a separate braid (twist) over the power and two speaker wires (+/-).
 
Will post pictures later today.
 
As for DD/DTS non-DIY-ability ? whatever do you mean ? License has been paid when i bought the set. I only reshape the receiver by moving it out of the original housing.
I wont be messing with electronics, its way over my head anyways

 

[bcg27]

Quote:

Well, the two thick wires are the most resembling antennae from all the parts i've seen come out of housings.
However, the 2 wires connecting both sides of headphone and electronics (one board on each ear) are a separate braid (twist) over the power and two speaker wires (+/-).
 
Will post pictures later today.
 
As for DD/DTS non-DIY-ability ? whatever do you mean ? License has been paid when i bought the set. I only reshape the receiver by moving it out of the original housing.
I wont be messing with electronics, its way over my head anyways

I think you misunderstood - I am sure those are the antennas, I am just not sure why the length is what it is. As for the DD/DTS, that's what I was asking, if you were using the exising receiver. Sorry if my post didn't make much sense.
 
 

 

[threedee]

Ok, got some tools that i've been lacking for small things like this.
A dremel (model 300), rotating table mini vice (50mm jaw), some other bits and pieces.
Vernier caliper, one thing i lacked in precise sizing of things, drawings made using good ol' ruler...
 
Stocked up on old scratched plexiglass yeah, i'm cheap. Still its the first go at plexi.
How do you properly weld plexi ? Will pure old acetone work for welding plexi ?
If not, what will ? I'm UK located, so have to be specific, cant really get weld-on here...
Also would like to try the welding apporoach instead of superglue/gluing...
 
 

 

[bcg27]

I have bought stuff from TAP plastic before, they have some great tutorials on their site: http://www.tapplastics.com/

 

[threedee]

Sorry for delay.
 
Got 250ml bottle of DCM (Dichloromethane). The stuff is amazingy good at sticking plexiglass (welding actually).
Apparently, you can get DCM on ebay in UK.
 
Today was cutting bits off, sanding/polishing and sticking them together just for fun.
Also finishing housing designs. Still need to get a 3.5mm socket.
 
Looks like final design will be a box of 105x75x36mm. Could save 4-5mm by removing partition between boards (3mm plexi), however it becomes messy to mount things inside....
Dont know, its late, will decide in the morning...
 
Tomorrow will be doing loom shortening. As it stands the loom is 45cm long, needs to be either ~6cm or ~3-4cm, depending on how i go about mounting boards inside (back to back or plain stack face to back...)...
 
Hit the sack in 3...2...1....
 
ZzZzZzZzZzZzZ..........
 
#Edit1# Ooooh... Also learned that Trichloromethane (DCM's brother), better known as Chloroform can be used to weld organic plastics, not just knocking people out... However THAT cant be obained freely... Must be nice working with it - start. then wake up for time to finish work and go to bed