[kahei036]

Hi all,
 
Not sure if it is appropriate to share here, as mine is such a small one compare to the biggies here (which all look very cool!).
 
I've recently made a pair of AAW W100 (CIEM). So I decided to pay a little to upgrade my gear (which was an iPhone). I bought a second hand iPod mini, and followed the guide on this board to have my iPod mini modded. Now I have a modded line-out bypass, why not making a dock cable and amp myself? I then made a dock cable with 3.5 out with micro USB for charge and data sync.
 
Get long story short, I decided to start with an old, but simple design - an A47. Here I would first of all thank Tangent's website, which helped me a lot on electronics basics. 
I've been making a few HPAs back in few years ago, those are "giant" (able to case 4x 9V cells in, you can imagine) and they are not portable at all. This time I tried to challenge myself to house it in a smaller case.
In terms of size I am quite satisfied  
 
There are few areas to improve though, it is running with 2 LiPo cells, but there is no charge nor protection circuit, I had a few bad experience of over discharge and damaged 1 or 2 pack of cells.
Next up I would like to challenge myself with MINT, with few modifications after digesting Tangent, as well as other materials, and understanding the circuit.
 

 

 

 

 

 

[HiGHFLYiN9]

Looks great! Nice job breadboarding

 

[2leftears]

Nice build, but:

There are few areas to improve though, it is running with 2 LiPo cells, but there is no charge nor protection circuit, I had a few bad experience of over discharge and damaged 1 or 2 pack of cells.

Best not use LiPo's then. Discharged below 3.0V They can get damaged. Below 2.5V most chargers will reject the battery as it is considered too dangerous to attempt charging (fire risk).

I don't quite understand why a lot of DIY-ers (and manufacturers for that matter) insist on using Lithium-chemistry based batteries. They are downright dangerous if not treated appropriately. Standard NiMh batteries are a lot safer to work with, and for the same power capacity are indeed bigger/heavier, but not disproportionately so... So for a phone, sure, but for laptops / cameras / headphone amps etc, why go through the trouble/risk of using Lithium chemistry? Remember all the laptop battery recalls over the years? And even Boeing have trouble to get that stuff working reliably :rolleyes:. Many airlines are now restricting the quantity and state of LiPo's you're allowed to take on board. Some are restricting LiPo batteries to only those inside the appliance, spare ones carried separately are sometimes prohibited. And with electric cars becoming more commonplace, expect a lot of burn-out wrecks at the side of the road over the next few years.

I also have a theory about the increasing number of fires happening at waste-dumps & recycle sites...

 

[kahei036]

 

 
Hi 2leftears, thank you for your comment. Yes before I start this project I indeed have read a lot about the cons on LiPo cells, however given my case is that tiny, there are not much choices left for me.
a 9V cell is slightly thicker than my case that I can't fit it in (Yes I used to use 9V batts for my portable amps)
2A and 3As are also out due to space in case and the voltage they can supply. With a pack of 4x 2A batts i can get only around +6V at most. Most opamps only run at +- 4V or above.. I also try avoid using DC step-up circuit, mostly due to, again, space issue within the housing; and personally I am kind of negative on such step up circuits.
 
These LiPo cells draw my attention, firstly of coz they are tiny enough to fit in my case; and they can be reused in my remote control cars (If one knows that well will probably notice it's actually a remote-con car battery!)
Also with 2-cell LiPo I can get +8V at most for a batt pack. Running 2 packs I can get +-8V, that can drive most opamps happily (Not MUSES01 tho, that needs at least +-9V)
300Mah per pack is releatively a low capacity one, but in my practical test my amp can run more than 10 hours. I am quite happy with that coz even my reborn iPod mini can't stand that long lol
They are also light in weight, 2 batt packs are slightly lighter than a 9V Alkaline batt, with similar physical size.
 
Anyway, thanks a lot for your input and I truly agree that one should strongly consider before they get on LiPo, they are dangerous and can easily die due to over discharge.
However, for myself, after above consideration and judgement I have chosen LiPo for good and using them with extra care

 

[99wombats]

Just finished this 12AU7 headphone amp (instructions), my first diy hifi project - got a bit of quiet hum I"m trying to get to the bottom of but pretty chuffed with it to be honest
Potentiometer knob and hex head screws to replace those cross heads are on the way
 
 

 

 

[skyhakuu]

 
 

 
 

musical fidelity combo + hd800 (house)
 
velvet+z3 in the street

 

[Vidal]

My modified DT990s - these have been recabled with 26AWG silver plated cable and have been fitted with a 4 pin mini XLR socket for use with a balance amp. I've added extra damping and the cable will have inter-changeable adaptors 3.5mm or XLR once the male mini XLRs come back in stock at Canford.
 

 

 

 

 

 

 

[kahei036]

Another attempt in a chocolate box. It's with a modified MINT circuit due to some parts restrictions. Running with gain opamp LME49710HA and buffer LME49600, it turns out to be the combination stated in NS datasheet lol.
 
I actually got the 49710s in hand for few years, but most of my projects are running dual opamp so it's hard to fit in. I decided this time to build a dual mono amp to have that in. Luckily after some opamp rolling it doesn't let me down, really a good one.
 

 
Close up
 

 
Did quite a few opamp rolling, maybe i will share later in the opamp thread.
 

 

[FallenAngel]

  Another attempt in a chocolate box. It's with a modified MINT circuit due to some parts restrictions. Running with gain opamp LME49710HA and buffer LME49600, it turns out to be the combination stated in NS datasheet lol.
 
I actually got the 49710s in hand for few years, but most of my projects are running dual opamp so it's hard to fit in. I decided this time to build a dual mono amp to have that in. Luckily after some opamp rolling it doesn't let me down, really a good one.

 
Very nicely built. Simple, elegant and a good design.

 

[gilency]

Nice little amp.

 

[Sunshine55]

After building my avatar amp, a Millit-Maxed. I had the tube bug and extra wood left over so built more.
The amp OTL 6dj8 / 6as7 / 5v4. Headphone Amp. (first)     Then i built a 5-in / 2-out audio switcher with
iphone, ipad, dap, dac, etc,,,,, perch. The perch folds down for transport. Switching is done using touch
sw's made of stainless steal rods taken from old CD player. I used the finished end as sensors to drive
a small pic which also controls the indicator leds and, the relay's contained in a metal cab also holding the RCA's.
All in all i am pleased with the way it turned out. That great looking high/low volt connecting cable cost
me $1.00 at junk shop for European (220v) travel iron. Cool the way things turn out sometimes. I do
love DIYing. Cables will get shortened when they find their perch. Cabs are 6"Wx8"Dx2 1/2"H. Sound is
better than my ears are used to so this unit will be with me for a while.

 
 
The Switcher

Touching left sensor advances to next input (led only) and the right sensor selects (led and relay).
Doing the opposite way round (within 250msec) selects the outputs, (front or back). Makes it handy
for front access of stereo 3.5mm input and output.

And if you think i may have a few grey hairs after cutting out, sanding,
and spraying that musical note stand. You'd be right. Again, the piano
hinge, and the back rest support (both solid brass) just turned out to
be the perfect size. Luck not design, just pure dumb luck as well as the
last peice of 3/8" walnut i had, which made the stand/rest. Go figure.

The banana jack and switch allow me to connect the metal cab to either cir/sig gnd or earth gnd.
All internal wiring is silver. Just a little audiophile touch.

 

[silvrr]

How did you join your corner posts to the sides and front? I am looking to do something similar and can't decide between biscuits, dowels or just a tenon type joint.

 

[Guidostrunk]

BRO! Your work is FANTASTIC! I do carpentry, for a living, and love the simplicity of the design. I would seriously buy for looks alone. Contemporary/Rustic.

After building my avatar amp, a Millit-Maxed. I had the tube bug and extra wood left over so built more.
The amp OTL 6dj8 / 6as7 / 5v4. Headphone Amp. (first)     Then i built a 5-in / 2-out audio switcher with
iphone, ipad, dap, dac, etc,,,,, perch. The perch folds down for transport. Switching is done using touch
sw's made of stainless steal rods taken from old CD player. I used the finished end as sensors to drive
a small pic which also controls the indicator leds and, the relay's contained in a metal cab also holding the RCA's.
All in all i am pleased with the way it turned out. That great looking high/low volt connecting cable cost
me $1.00 at junk shop for European (220v) travel iron. Cool the way things turn out sometimes. I do
love DIYing. Cables will get shortened when they find their perch. Cabs are 6"Wx8"Dx2 1/2"H. Sound is
better than my ears are used to so this unit will be with me for a while.



 

The Switcher


Touching left sensor advances to next input (led only) and the right sensor selects (led and relay).
Doing the opposite way round (within 250msec) selects the outputs, (front or back). Makes it handy
for front access of stereo 3.5mm input and output.


And if you think i may have a few grey hairs after cutting out, sanding,
and spraying that musical note stand. You'd be right. Again, the piano
hinge, and the back rest support (both solid brass) just turned out to
be the perfect size. Luck not design, just pure dumb luck as well as the
last peice of 3/8" walnut i had, which made the stand/rest. Go figure.


The banana jack and switch allow me to connect the metal cab to either cir/sig gnd or earth gnd.
All internal wiring is silver. Just a little audiophile touch.

 

[Sunshine55]

 Very kind words Guidostrunk thank you. That is the last of the walnut
and maple from building my main system. OK maybe a few small desk lamps.
I love the smell of wood, the texture of it, the warmth it radiates. Hence the
orange soft led's on the front and the glow of the heaters is a perfect combo
and perfect for relaxing and listening in the eve's quiet hrs.
 Of coarse i had to chop down one walnut tree and one maple tree to get it.
Truth be told there are 5 pieces in total, the other two are pwr sply and
phono-preamp designed by Bruce Heran which are about 95% done before
I got sidetracked. Have all the parts no time.
Silvrr,,,, the box is small enough to carry in one hand and made of 1" walnut
and 3/4" maple. It stands 2 1/2"H x 6"W x 8"D. Granted if you threw it against a
rock or boulder it would break. But, you could drive a truck wheel over these
boxes and scuff-up the 600 grit sanding. Butt joints all the way. Strait, clean
cuts and tube clamps for a day per stage. <24 hours no cheating>>. Very good
to scuff up the mating surfaces though.
 
Always use wood between clamp and cabinet surface.
Keep moist cloth rags near to wipe all joints of glue that seeps out. Do it
immediately after clamps are tight and secure. Any glue let soak in will not
allow any finish of any kind to penetrate the wood surface. Which translates
Eewwwww when the final stage of the varnishing starts and WT.....oh noooo
I used a 18" table saw with 8" blade,and a kitchen blender motor for power.
1- clamp 2 side panels to top.   Do this step first and use the back panel between
the sides so when clamping the sides to the top they are 90deg
2- clamp 2 front posts to front panel. Flush with each other on the inside surface.
3- clamp 2 back posts to back panel. Same flush surfaces on the inside.
4- clamp front to top and sides.
5- clamp front, top and sides to back group and you are done.
It is not going to break unless deliberately done. Then even biscuits
won't mend a broken heart.

 

[Sunshine55]

In this set the wood boxes are each covering
aluminum Hammond chassis for shielding due to
the high gain stages of the phono-amp.
Here the wood "feels" best.
 
 
This is when the color and warmth set in. After spraying
with varnish.
 
 
Here the pwr spply is done and tested under load but
preamp is about 90 to 95% done. Good job i can work
with wood cause i can't take a pic to save me. Sorry.