DIY resistor for DAC current to voltage conversion

June this year is my zero writing month. Don't want to skip July so here it is another DIY audio adventure.

My tweak darling, the Sony CDP950 is almost weekly being changed. I used it for learning both digital & analogue wise. At DIYAudio I came across a strange resistor made by John a.k.a EC Design. It is quite complex to be made- although fully doable in my workshop. Here is my 'dream' Ri/v - the resistor that convert current out of the DAC to voltage that goes to the tube grids. In my case its valued 33ohm.

A beauty isn't? (hopes John wouldn't mind I use his pic.). Why all the troubles? well this DIY resistor promises low capacitance - non inductance - and high wattage. All good for tiny current out DAC.

What I can not get are a coated resistance wires & patience for winding it.  Being a naughty DIYer like me,  I have once hammered several of those white bricks, just to see what's inside :). It turned out that for low R value the R is wire wound. Higher value some kind of carbon film. Hmm..this brings me to an idea..

So, armed only with double tapes and 2 pairs of white bricks 39R/5W here we go :

The tools are 1 hammer, 2 pliers, cello-tape, double tapes (thick & thin semi transparent), scissor or a cutter, a tweezer.teflon tape...thats it.

Take care not to break the wire from the end cap. Tape the wire to the cap & legs for strength

Thick double tape both end stripped & glued to the table and start making zig-zag pattern of the first wire lay up about half of total wire length (my case 28cm ~ 1ft). plan for the double tape length.

Cover the first lay up with thin double tape, next lay up

The first lay up is now 'insulated'. Start now with a second layer, now you know why I need a semi transparent tape :).

Measurement shows a lower R value than the original 39ohm. This happen once you unwind the wire from the ceramic center piece. Not to worry & its closer to my 30ohm target :).

Cut both ends, add another thin double tape, peel wax paper on both sides & start rolling

Two DIY Resistors :)

Rolling & teflon taping. measurement shows quite acceptable 'tolerance'. After rolling the tapes the R value goes higher a bit.

In action :)

The sound? well the 'cocoon' beats my Philips metal film for sure, and about a 'tie' with the pink Takman's, not yet decided though ;). Highs of this DIY Ri/v are quite breath taking...

But...hold your horses, recent discussions on DIYAudio with EC reveals that this DIY Ri/v is not completely non inductance yet. But it can be made non inductance, using a so called Ayrton-Perry_winding and for this I need to insulate the wires using a proper lacquer. Not so hard to do compared with 5m long EC's wire :).

So ..my adventure is to be continued...thanks John..

Don' buy just a faucet - buy a heavy one!

Did you ever change any of your water faucets at home? How often and how many already?. Well I'm kind of lost my count here, and add another count last long weekend..sigh...

There..the bad faucet number XX..totally new, bought in a well known hypermarket (c4), a well known brand (k**m****r), hyperlight, hypershiny and last but not least, hyperItaly as shown. This thing cost about 1.5USD, comes complete with thick lovely blue hanging plastic tag and a teflon tape, nice bonus..o is it?.

The usual routine: closed the central water tap, removing the old bad faucet number XX-1, happily wrap the teflon tape (my favorite thing to do)  laa..di dam..di dam..put and turn the number XX to the wall socket, there goes the wrench..laa di dam...la..di..WHACK..what the...? Is this faucet that bad? It's just can not took even the light twist of my light wrench..whaaa...!!.

Did I need to comment on the design - material - fabrication? No..not a bit. Even the fluorescent colored plastic faucet is doing better than this hyperItaly. This is an outright robbery...where is the Ombudsman here? Hellooo?..knock knock!.

Do me a favor. Just buy a heavy real brass nickel chrome plated faucet. It will cost you 10 times more but will safe you 10 years of not using those red plumbing wrench...while I left here with very expensive teflon tape...thanks for reading..

Good, and not so good design, Plastic Clip & Microphone Jack

I've thought that after posting mainly DIY audio stuff, its time again to look at design things. First, a 'sorry' microfone jack for my son's electric guitar and second a deceptively simple clip.

I've bought these poor jacks to replace low quality cable that comes with the guitar. Just rush to nearest small electronic shop around the corner & found very low quality jack, asked for another but to no avail :(, My son just want to play (read: make noises..) so I grabbed a pair knowing I can fix them temporarily.

So whats wrong with these sorry jacks? See pic below, the paired one. Built is very poor, thin and flimsy solder prongs, cable grip that's too short to fully clamp my light brown Canare mic cable.

But the biggest problem is that the ground shank (negative) does not stay fixed to the threaded body, in fact you can easily turn the shank relative to the body. Now that's a good design or what ?. I can imagine my son will make more noises - pops and cracks all the time due to poor ground contacts...

The temporary fix?, I've soldered the prong to the body - so that's solved. The Canare's sounds cleaner and more full bodied against noisy giveaway cable :)..

Since I know this is a temp-fix, I bought another pair, a much better build and sturdier thicker metals and you can not turns any of the shanks. The clamp just can grip the cable nicely with slight overlap. Just a week ago or so the sorry jacks gave up, so 10 minutes jobs with this new jacks and my son can make more noises...sigh..

What I don't understand is why on earth you make things so badly? You'll do badly on the market, you've spent at least the same amount of money and effort to produce them and what a waste of resources? Think about the shiny metal plating process that pollutes river?. Beats me..that's why we need industrial standards, in our case SNI-short for Standar Nasional Indonesia

Now to the good executed design..a simple plastic clip shown below. What are they used for? It's used originally for bread plastic wrapping, yes to tighten the 'bag'. I always hate the green tapes - while they are a breeze to apply for the store clerk but not to us the user.

Now somebody very smart have made both the store clerk and us happier. this clip is very easy to apply and to detach. All plastic design philosophies are used..in short, one piece, integrate all functions in one single part.

Lets see, there is a hinge, a toothed ribs for better grip, there is a lock that function very well, easy to lock, not easy to open unintentionally but easy to unlock ..now..this locking things sound familiar to me? an echo of my past..yes it is one of the design requirement for an aircraft door - even after crashing !...how about that!.. for a simple plastic clip?

None of  any car doors in the world even come close to this clip! Now don't get me started on public transport doors in Indonesia ha ha....(this one is unique..you can throw garbage and yourself in and out the door while driving....)

And the best part of this 'simple' clip is...see for yourself....:), my 4 thumbs up for the clip designer

iPod Mini alive again!

Last year sometime in November we got lightning strike at home, just when my daughter sat in front of her (and our family) PC..She told me blue light appears accross the main board. The PC is dead, so does the cable modem, the printer and my daughters iPod Nano..sigh..but thank God she is OK.

The Nano got so hot she put it in the freezer!.I wasn't at home. Alas it was over then with it. So with no budget after buying new motherboard-second hand-Phenom X4-cable modem, her dead iPod mini is my target operation. Thought that only the battery needs replacement.

Spend a half afternoon to read how to open the thing-and finally have luck to change the battery after admiring the Wolfson DAC-Phillips chips-no wonder people like the sound of this 1st gen mini. Apple just wants only  the best for their products that time. But the display shows discouraging message..a frowning face appears then followed by an URL..bah..., must be the mini drive that gives up..so did I..throw a towel.

But with luck and persistence of a DIYer-I found this link..of the late Mark Hoekstra, who back then in 2007 have already done it!..replacing the venerable minidrive with 4GB compact flash memory card. A couple month later and it's just yesterday I found a 4GB Transcend CF card that known to be working well with iPod. I've spent a couple of hours and yes..it works, here are the pics. Veel dank Mark..you've leave us wonderful knowledge..

The mini drive-new batt-and  CF card

This thing makes the old iPod mini to a cult status..(Wolfson 8711 DAC) and yes there are people out there tweaking this little guy !

after restoring with iTunes....

With backlit ON & the busted Nano..Apple proprietary chip in there and a korean memory chip..:(

This morning I've made my daughter happy, also my son who got new iPod shuffle for his birthday to day..not to mention my wife who otherwise will spent more money!..So, please throw away then your iPod 1st gen...to me :).

Sony CDP950 hardware mod-wooden transport

After modding this Sony CDP950 heavily, these are the results.
Electronic wise, well never ending tweak that is :). Found during a recent blind test with a poor result ha ha..It turns out that the R value for current to voltage is very important, and you need really second-third even fifth opinion to judge the sound when you're constantly modding and didn't know anymore of 'correct' sound. So it was my take for another lesson.

Hardware wise I consider it finished..yihaaa!. Acrylic plates does wonder and also a quite difficult task in taking care of the old transport. It's all wood now :)..not the famous Phillips VAM or something like that , I dubbed it Sony WAM :), short for Wood Augmented Mechanism..just kidding :). here is the tranny cover

The 'new' Sony CDP950 'Lampized'..thanks again for your mail Mr. Fikus..
A broken beam of my workshop roof, or a part of it :) & a design drawing
Made some noises..
Fitting & mating plastic, wood & the CD player..

Adding a nice old teak top layer
underside of the 'WAM'..
Nice gold plated springs..(guess where the h**** I've got it..)
Fits well..
fastened & adding brackets..
Well..more pictures this time. As February was a really busy times. Also recently this CDP yet again showing another sickness. The CD just turns very fast counter clock wise. After cannibalizing my 'spare' Pioneer LD player for few chips, particularly the spindle motor driver chip. this old guy just runs well again. Now back to that never ending tweak again...thanks.

Sony CDP950 TDA 1541 NOS ed and Tubed

I have to confess. I'm really excited with my Sony CDP950 with 20years old TDA1541 DAC. Several tweaks & heavy modifications resulting upgrades in sound each and every time. I always set my mind towards the final tweak-a tubed CD player- since last year and starting to spare my money for collecting tubes, HV transformer and other component. And of course continuing learning how tubes works.

Last tweaks were the opamp change, the bypass operation here and the non-oversampling things.

At the end of last year I've heard that a Blind Test for CDP and/or DAC going to be held in January 2010, so it's time to put the effort. Top cover is cut for tube base plate and top loading system. Also 2 left over 8mm thick acrylic plates for beauty and tube protection were made with my own hand :).

Schematic is as always..from Mr. Lampizator himself, a SRPP with 2x 6N2P-EV, for this I thanks Pak Dino. I plan to use hybrid tube rectifier - AC heaters all the way and 6X4 tube-USA origin I got as a gift from Pak Ado. HV tranny, sockets and resistors were from Pak Alex. Thanks to these good people! I can keep the mods at low cost, in term of materials that is :).

Socket, components & wiring were planned, sketched & routed. Keeping with my Reuse-Reduce habit, wiring and, diodes and the capacitors are all used ones.

The simple plan is you tap the Iout signal from the TDA1541, route them to the 6N2P grids. There is a 60-100R from grid to ground which convert the current to voltage. Here is the I out wire, doesn't have to come out of PCB bottom this time :)

Piggy bagging the HV tranny..

Refinished top covers & tube base
Now the messy, tiring & fun parts...no..not that fun anyway..
I blew my cheap compo speakers-I think the tweeter just gave up-they got 75VDC for a second or so..sigh...stupid me. Also I've got 255VAC on my right hand fingers..boy..felt the jolt up to my arm pit..the hairs there felt smoother now :). How about the sound?...there is music..very low level..even I have cranked up the volume..lots and loud hum, check and recheck everything..no result, de solder & resolder the R's..also not helping. changed the AC heaters to DC with 7812 regulator..even worst..I gave up, just pull out the tubes- de solder the 220VAC from HV tranny and get ready for the next day Blind Test just with Non Oversampling tweak.

I have said the NOS tweak is a leapfrog compare to Bypass tweak. The blind test result confirmed this..at least the for Jury, session 3 got number 3 out of 5 players. This old CDP-loses to would be winner-CDP333esd nosed-reclocked-BGed and external tube buffered CD960..interestingly 4 out of 5 players using TDA1541 !. The non Jury said other way..last position for my old CDP..so..I have to make my CDP really sings or else...

In order to understand what is going on, I've made a simulation in orcad, yes there is 6N2P Spice model out there. Simulating the SRPP with Iout of 1kHz at 0.4mA (TDA1541 datasheet) shows nice high Vout :0... So what might happen? Searching the Lampizator site for (hidden) clue..no result--Mr Fikusz hiding something? nhaaa!... My tubed CDP very low Iout-Vout signal indicates that the Iout from DAC is being corrupted a great deal, like everything here in Indonesia :).

I can only point that the BB OPA2134 as the I corruptor !. Gothca...the opamp pair on temporary detention now. Turn on the CDP next the HV switch...yes..a big YES...Ingram Washington sings loud and clear!..almost no hint of hum..this AC heater tubes!..

Ingram Washington sings :"...What the difference a day make...." this day for me was 1 week after the blind test. The OPA2134 now permanently out of my CDP..too bad though as I can not directly comparing NOS-OPA2134 and SRPP. Or is it necessary?..No it is not necessary.

The difference is very clear right away. I will spare my comments for later :)..my wife just shortly said.."empuk"..means (maybe) "smooth" in English..that with up to now unbearable to hear CD from David Foster & Friends..

Wiring & sound testing this way :) with Gainclone amp and 2 samsung small speakers.
Bunch of resistors to try. And finally testing in my system..with a C out coupling rig for finding the right caps. I'm tired but fully satisfied. There are some minor tweaks must be done on the HV PSU, R values & types, Cout and last but not least the CD transport itself..maybe a Phillips CDpro2 transport Clone..:). Thanks for reading my DIY audio adventure.

Rice Cooker, Good ones?

Last year I have started this blog with a design case. Inline with 'tradition' here we go again. This time you may ask, what the h*** is that stone doing on top of my rice cooker?. Are we (God forbid) so poor that we eat stone?. No..please no..

The answer is here, no stone-the cooker cover won't close, I eat no rice, so does my wife & kids, o yeah..the cats as well :), what has happened?

I've seen too many cases of plastic products used in the wrong way. Plastic and heat do not go together see here . The same goes here. The blue hook is intended for locking the cooker cover to the lower part. After few months, yup, it just lost the grip and hence come the stone. I have once broken a plate full of rice because of my slippery hand :(.

Maybe, just maybe, the designer have calculated the hook well, but the maker just want to have cut the cost by using recycled plastic. Or its just another bad design..gosh..

My wife has learned, she bought a new cooker..no..not the same brand..ever!, see here the good solution? Yes..a steel hook, you can go very very far with steel in 110 centigrade..lets just hope it will not corrode too fast, as the hook is galvanized..bravo C*****S