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

LM3886 Gainclone, My Fisrt DIY Amp

Exactly this month last year in 2008 was my first step into DIY Audio. Full of doubt I've started with the popular LM3886 chipamp a.k.a. Gainclone which gained enormous popularity among do it your selfer around the globe. Never good in electronics, don't understand a thing, but out of love for my daughter I've tried it anyway. So first I made 2 'bird nests' and I'm surprised with the sound. I have decided since then never to buy branded amp anymore, make them yourself. Its cheaper, educating, fun with many friends and most importantly much better price to quality ratio.



2 proper casings was designed & crafted in our workshop, for power supply and the amp itself. Here is the 2 PCB's and a solid aluminium heatsink.

A 'see-through' amp casing, to date contains different and better components.

The pairs behind and front.


Wonders happen when you love your family and friends..long live DIY audio.

MP3 USB-MMC Reader

This is my recent DIY audio thing. I found this USD 7,- little handy MP3 player that fits me and my family needs. My car audio head unit, a Sony cdxGT700d has lost its CD mechanism for quite a while, so no CD or MP3 anymore.

I'm also tired of using my old Sony discman as source in car. Sounds quite ok though, after some blue- tack tweak, but I have to put it on my lap when driving or the player just sputter, cough and more when I hit road bumps. Here is the 'replacement', a simple cheap USB-MMC reader, feed with 5VDC. Add a 5Volt regulator such as 7805 off you go.


There is an Aux in, it can only reads MP3's put on the root directory of your MMC/USB. Read the file in sequence only, no shuffle thing, its ok for me and many motorcycles rider who use it. At the beginning of each track the volume increased to full level in a second or so and gradually soften when track skipped, one at a time. It also memorized the last track it plays after shutdown.

For my kids, there is another version, bit more expensive but still below USD10 :). Provided with a remote control, FM tuner, display, EQ function, maybe shuffle thing as well...

Some tweaks are needed after listening familiar MP3 ed tracks. Four very small electrolyte caps, 10V, 100uF replaced by good Elna Cerafine, 16V, 100uF I have on hand. Boom...the sound goes to higher level!. Add blue tacks on top of the chip, the crystal and the sounds settles in orderly manner. Definitely it sounds better than my brother stock Simbadda MP3 player.
I have learned though, that how you rip the CD is very important for the sound quality. My first test rip is using Cowon Jet-audio. The result is quite OK, but after comparing with the original CD you missed quite a lot, especially in staging. Even I have ripped in dual stereo. Then a friend told me about EAC, Exact Audio Copy. I have read it in 6moons some month back..I'll try this for sure..

After a few days of use, I decided to give this cute player a cute casing, a beautiful solid teak one!, finished just with..teak oil...hmmm..

Analogue Volt Meter, Revived

Sometime, we in our workshop just throw away damaged things into a drawer. The same goes with this cheap Heles AVM, after a few use it's just don't swing anymore, goes into one drawer some years back. When I bought old capacitors recently, I need to see needle swing on the meter, Digital Volt Meter is no swinger :). So, in line with my principle 'use whatever you have' , old Heles is my operation target.

The problem turns to be a loose copper wiper and wobbly shaft of the disk. Thewiper was just fastened by 2 plastic pins that was melted by a solder to clamp the wiper down. Well, this is a good plastic design practice for non moving part, for moving part you need larger pins or a long rib.

So here are the fix, add a screws to the shaft and wiper. Now the needle swings !.

But the fix brings new problem..as always, a solution creates new problems :(. There is no room for the screws, so a 30 minutes fix became 1.5 hours... Bottom of the casing is drilled, then cut a jelly cup bottom (remember..use whatever on hand..), epoxy-ed them..voila!..


Another problem, the meter just does not want to stay put , so add 4 rubber pads, cut from black foam I have in my garage-double tapes them..


finito..and still fit in the old box ..., mother earth and my wallet is saved again, just 2 things I have to throw away..the casing cut out and a jelly cup with no bottom..now lets swing!

Sony CDP950 Tweak Part 3 : NOSed

After enjoying my last tweak on CDP950, its time to see 'What NOS is means to me'. I've got info from The Lampizator site a while ago and made a plan on real PCB, here it is on bottom side.


This operation needs careful surveying of actual pins on the PCB. The job is really bypassing the digital filter chip CXD1088 who does the oversampling. The 1088 got its inputs from CXD1125 then outputs to TDA1541. NOSing is going direct from CXD1125 to TDA1541 with the help of shifter 74HC164, more details please check Mr. Lukasz Fikus site.

The first step is lifting the jumpers and resistors on the far side (from the 1125 & 1541), I use solder suction to do that. Then the 74HC164 soldered and glued to PCB, I've bent flat all its pins for easy soldering, see below.


Second step is to insert the wires (UTP) into pin holes of lifted jumper-resistor to the top side of the PCB & soldering them


Woow..looks easy, but I've made one mistake, it has cost me my brother in law amp..hiks.. :(. No sounds at all came out from the RCA, then I tried to short the R's...yep, some music (Andrea Bocelli-Amore CD) then silence...the amp is dead. Then I checked the plan, yes a mistake. Wire from 1125's pins 76 and 78 is the other way around, the wrong one it is, shown on the last two pictures.

Fixed them and YES...I heard Andrea singing through my throw away cheapo earphone..I knew the sound is already very good even with this horrible earbuds.

How is NOSed CDP950 sounds?..well, I think I'm closer now to my goal. It is a leapfrog from my last tweak, here are my early personal review :)

My systems : source CDP950, PreAmp Aikido DIY-6CG7-6DJ8 tubes, Power Amp DIY Aleph J clone, Speaker Magnepan SMGa.

Ze Sound : Wide and Grand, all the details & ambiance, effortless, not one bit tiring at all, you can follow each instrument easily. Timbres are really more correct. I'm not listening to lows, highs and mids anymore everything are there.

Surprises, compared to second tweak :
Some fast beat & complex tracks I usually have skipped due to unbearable & tiring sound now just opened up, no more congestion--newest CD from Dianne Reeves, Renee Olstead are full of them, hey its not the recording! Its YOUR CD Player!..

I hear many clicks and ticks and garbles during track change, pause and stop. I think I will live with them, or I have to look for muting schematic later on :)

Conclusion :
Don't blame your Pre Amp, Power and Loudspeaker just yet. It turns out that they are more capable than I've ever thought of, given the best possible source, that is, my CDP950-NOS..(..soon to be tubed ha ha hah...)

Now I urged everyone I know to NOS their old TDA1541 CD Player. Last but not least, really BIG thanks to Mr. Lukasz...

Really Good Designs

Here are two good designs in the house. Used them frequently as good example for my students. First, my daughter's first iPod, now no longer functioning and needs battery change, and an ice tray.

Where are the good design aspect on this nice iPod, beside the styling & functionalities?. Well, they're the little grey spot at the center of the holder and the holder itself. Why?. The grey spot is made of silicone rubber. Without it the iPod just drop-off the holder to the floor...bang!..

Why again?. One of the reason people using rubber is because of they increases friction, things dont slip easily, think of your car tyres , underneath your desk foot or under yours!. Other function is fluid-gas tight sealing, that bring us to birth control or health issue, but its completely off topic here :).

Now it's the holder turn, it has to be engineered correctly to push the iPod against this rubber spot. Not to firm so its too difficult to put in the iPod, and also not to weak so the iPod stays put in it.

How does it works?. The friction works if we put a force perpendicular to the friction surface. So we know now why the holder has 'wings', they're there to generate clamping force against the grey spot.

This design aspect requires deep tought in ideas, design, engineering and manufacturing. Only a talented designer will came with this. Oh yes, I can imagine how the 'American' engineers going very tough and uncompromising against Chinese Manufacturer on plastic materials and holder dimensions ;). My hat's off to the designers!.


The humble ice tray.


The second example is my 10 years old 'Korean Made' refrigerator Ice Tray. The trays repels ice cubes by twisting the tray handle, so a shearing deformation occurs between the ice and the smooth plastic wall container..then the cubes fall.

Very clever, just what we have to do to get ice cubes out back in the 80's. Take the tray out, put under running water and bangs and twist the tray :) to get the ice.. in short, making some noises.

Also heavy engineering must be involved here, and prototyping for sure to check whether the design works. Plastic material used must be of high quality..there must be no too critical area on the stressed tray...here are some numbers.

10 years x 365 days x 2x twists = 7.300 times and still going (I bet the manufacturer aims for at least 100.000 twist action..). Now add same amount of stresses in the container, because water expands little bit when frozen, also add temperature change from 25deg C to 0 deg C repeatedly. Whew!..that's a lot to be considered. Even the collector tray below has cracked its bottom, the test of time is unforgiving. That's what it takes for a good design, reliable functioning.