Selasa, 29 Desember 2009

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.

Senin, 23 November 2009

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..

Jumat, 20 November 2009

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 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 lets swing!

Minggu, 11 Oktober 2009

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...

Minggu, 13 September 2009

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 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.

Jumat, 24 Juli 2009

Sony CDP950 Tweak Part 2

Now I'm not feeling very well today, and just rest at home, let continue with my CDP950 tweak story. After changing the standard opamp to OPA2134, now is the turn for heavier tweak operation. My reference is a site called Lampizator run by Mr. Lukasz Fikus, I respect this Polish guy works. He is a no BS's just do it yourselfer type. It took me about 1 month on-off to study his stuff & my actual Sony PCB. Some work to reach 'little' audio nirvana eh?.

The operation is to bypass the TDA1541 DAC output from the first OpAmp (OPA2134 is now permanent), from first opamp output a wire is soldered to a set of coupling capacitor then to extra set of RCA plug. Sounds simple, but when you look at the PCB?..confusion is assured :-). Things getting better when I got a CDP950 schematic explaining connections in the DAC-Audio ouput area. Why this operations? the old CDP950 will sounds much better!, less parts & damage to the signals, Mr. Fikusz said. And after more than 1 year doing DIY Audio & hearing friends CDP hard for me not to agree. Now is my turn to hear the tweak my self.

step 1 , identifiying pins on PCB (opamp output & ground)

step 2, soldering wire to first opamp output
step 3, soldering ouput capacitor (phillips MKC 2.2uF) , RCA plug & ground. I like to keep the original fixed RCA for comparison

step 4, Now I can test the new sound!, and ? ...wooww..all I can say is that I could not believe that I have spent >17 years listening on this garbage CDP. I never liked the CD sound anyway, that is why I never upgrade to new CD player. Liked the old vinyl best. Now this almost trashed garbage player is my tweak darling.

I'm not just stop here, I know the sound can always be better and there are another steps to CD audio nirvana : making this 4 fold oversampling DAC to a non-oversampling or NOS DAC, then add a pair of tube buffer..long way..
But first just experimenting with coupling caps, better wiring, and variable output also bypassed. Coupling caps of the DAC also a tweak target using salvaged mylar caps from thrashed Blaupunkt Bremen car set. Another ways of reusing parts & save mother earth. Below, trying the sound of Russian Paper in Oil 2.2uF K75y-24 (the green thing).

above : harvesting result & Blaupunkt PCB, the mylar caps are 100nF, just the right value!

Final selection of coupling caps, I settled with paralleled yellow Phillips MKC 2.2uF, Blue metalic EroFoli 0.22uF, Back to back unknown electrolite 47uF (guess them Epcos?), in total of ~26 uF. These caps, especially after adding the electrolite, sounds very open-transparent , balanced low-mid-high. Overall the new sounds are very sweet, fluidic & analogue, now my Thorens TD320MK2-BlackPearl MM Cartridge-Cambridge Audio Azur Pre-MM have to fight very hard I must say.

final selection

Other tweaks are changing the diode rectifier to a ultra fast ones (BYV27), changing the old motorized pot to the sweet sounding little 50k ALPS green, replacing PSU Caps of DAC to Elna Cerafine, also a mishap of my tweak frenzy..a lesson learnt on my account. Changing DAC coupling caps the original 100nF ceramic cap//100nF mylar to Wima// mylar & a pair of (Auri?) MKT at the MSB pins. Theoretically the sound must improve since the Wima's and the MKT are better parts, the resulting sounds are worst. Details are lost, far from airy..well, once you get the correct sound, you must restrain yourself, except if you've got 14pcs of Black Gate NX of course!. Off with the wima's!, luckily I still able retain the sound I liked, just clean the solder pads thoroughly with acetone. I heard scary stories that you may not be able to go back to 'original' sound.

Diode, ALPS & tweak mishap

I'm completely astonished by the sound, and it's not even using 'better' op-amp than OPA2134, not NOSed yet & no Tubes. Thank you to all my DIY friends & cheers to Mr. Lukasz Fikus. Do not believe me, just try it yourself!.

Kamis, 16 Juli 2009

Sony CDP950 Tweak

After a friend recommends a bypass operation on my CDP and reading a site called Lampizator, I decided to do just that. The CDP output is bypassed from DAC-first Opamp, to coupling cap then to RCA output. But first, before executing this heavy surgery, I just change the cheapo JRC NE5532 opamp with audio grade Burr Brown OPA2134. Steps are quite easy, removing the opamps, resolder a good pair of IC socket, install the OPA2134..thats about it & enjoy..

How does now the CDP sounds?, quite surprising, it just sounds like a more expensive player such as Nakamichi CDP1 which I have heard for several days at home, vocals are warmer with touch of 'air'-singer's vibrato are now more pronounced, overall my CDP sounds less harsh & more enjoyable for long listening sessions..hmm, couldn't wait for next tweak.

Minggu, 07 Juni 2009

power point, good design until it's broken

Before I plan to continue my tweak story on my old Sony CD Player, lets us see this power point problems.

Like other people, I like to plug in those power cables to one hub. But beware of the rating. No more than 1PC and 1 LCD monitor, plus bunch of wall wart adapters. I bought this one some 4 years ago, no problems until now. I have selected this one from bunch of others.

Things I've looked from what was visible underneath the packaging :
  • wire thickness or gauge, the thicker the better
  • available ground connection (3 prongs connection), safety reason
  • thickness of brass receptacle & ground contactor in the socket, for durability & contact firmness
  • plastic housing quality, choose heavy one that easy to clean & does not change color
Conclusion: this power point is a good one!, good designed & made, it lasted 4 years

Just a couple days ago, the red lamp switch just gave up. It made a sparkling noise. That was no good for my daughter's PC and LCD monitor. In fact, the LCD went in to protection mode. No picture at all. One of the mains pin is I have to cut the cable & hiks...throw away the plug..sorry mother earth..

When I tried to replace the switch, it turned out that the manufacturer used special screws, that need a special tool to unscrew them. Well...screw the maker!..they just want us to throw away the thing & buy new thank you..not me! the planet you know?..

Here is what I do to open the case & replace the fragile switch (no lamp this time). Lamp gave heat, heat is the enemy of plastic..they went broken because of long time heat exposure.

I just cut the screw head with mini grinder wheel, along with plastic casing , just deep enough to create a thin groove for unscrewing, but still retain the screw bosses on the casing. The rest is history. This power point will go for another 4 years and I feel good saving it for the trash!

How about the design?.. Its good up to the switch durability. On the end product life cycle? such as design for servicing & for environment protection? I'll give the maker zero out of 10 for making us throw away things and buy another.

Kamis, 09 April 2009

Sony CD Player Laser/ Optic change

Finally I have replaced the old optics of my very old Sony CDP950 CD Player. That is after many weeks of frustration due to weakened laser optic (type KSS150A). Many hours I've spent to adjust the small trim pot (just below the lens assembly, on the back side), tracking & reading is getting worse every time. Hmm, it time though to look for new optic. Asked around some shops..there are no KSS150A everywhere.

the kss150A

No wonder, this little guy is older than my daughter!!, bought around 1988, one of the second generation of CD Player. In one shop one guy advising me to use a newer type, the kss210, he is a honest man, told me that some player can be replaced some not..price? less than USD 4. What the heck, I'll try that along with a new disc motor with long shaft (mine is wobbly), availability is very good here. Old motor is made in Taiwan, the new one is Malaysian made.

old disc motor

Got home and soon the Sony is in pieces.., removing the motor you'll need to desolder the board. I've marked the + and the - of the motor. Next is removing the old optic assy & install the new guy. Whew..that was easy!. The new motor is also installed as marked in the PCB.

bottom view of tray

See the green board? That's the motor PCB. The right side motor is the tray motor, the middle one is the disc spinner. Just below is the optic, the one with wires and red connector. Here is the top view.
Also the variable output capacitors are replaced, see below.

Now comes another lengthy frustration, everything re connected, turn the power on, put a CD..well it's spun very well..but, where is the music? reading? time on display?. Well..its might be not as easy as I've thought, I remember the shop owner words.

I noticed that the CDP main board has many trim pots, wonder what they do?. Before I tried to trim the pots I marked them. So I know their original positions. First the trim pot on the luck. Then the rest of the pots on the mainboard. Yes, they have some thing to do with the optic head & motor speed (the servo things!), still no 3 AM I thought I'll have to say good bye to my CDP950.., pity though, they have many quality components. Nichicon Muse & Elna Duorex electrolytic capacitors, nice resistors & ceramic capacitors, there are also high quality silver mica ones. And most important..the now sought after TDA1541 DAC/ digital analogue converter.

I thought I'll go to sleep then. The next morning I need to listen to some music (I'm still felt frustrated all right), I picked up a DVD player below our TV set, hooked & put a CD and..blah!!..the sound is very harsh, tiring to hear... I thought that some tweaks will tame this USD 20 player...I really missed my CDP950..

Again, the cheapo DVD is in pieces, changed the capacitors on the power supply board, they've used a switching one, with very small transformer. One capacitor near the trafo is bulbing on the top side, waiting to burst open..who to blame? Ok. everything is re installed, put a CD and hooked back to my system without top cover. Hmm..the CD sound's stabilized now..but WAIT!!..why is the disc turns the other way as my CDP950?, this DVD turns the disc clockwise viewed from front side...could it be?..that my CDP?..or this DVD is wrong..or?

I rushed back to the Sony, desolder the motor, marking is ok, + on PCB is + on the motor (red dot)..ok, now resoldered the other way around, + on PCB is - on motor, put all things back..MAGIC!! CDP reads the disc flawlessly, tracking is excellent, track changing is lightning is my tweaking DIY audio story..really full of surprises. Next, this CDP will get custom top loading!. The tray system is not working well. But for now..welcome back my old fellow!!

Jumat, 20 Februari 2009

Bad, Bad Hammer, Bad..

I thought this post should be about DIY audio..until a couple days ago I found a smallish (broken) hammer. This hammer was new, bought by a friend because we do not have a small one.

Well this post is going to a BAD Design Case again, or to be exact..bad material selection, bad manufacturing process..bad quality control (doesn't seem it has any)..God know what else..

Ok, here is it..

I'm kind of speechless when I saw this pretty hammer. The material used is bright cast iron instead of a forged one which is a standard in the (good) hammer industry. Also the head is broken right at the most critical area and happen to be less material there. Have you seen a (good designed) hammer bulged around the hole of handle attachment?..Exactly! Here, some more pics.

The label says "Target" Contractor Grade ..Graphite..whoaa!!, what contractor? house of cards for sure ha ha.., another look how the attachment hole looks like, far from smooth, just waiting for a small crack to emerge (this material is kind of brittle) and then...thwak..broken

The only good design here is the color selection, it's pretty & catchy, makes my friend bought it, ..also the wooden handle is stronger than steel ha ha...too bad I didn't saw his expression when it happen. I'm still you?

Kamis, 29 Januari 2009

Check your Loudspeaker Crossover

It was last week, when I brought my 'analogue arsenal' to my Dad's home. He want to listen to old vinyls he discovered lately in the house. All set up, all LP's cleaned (washed to be exact), put an LP from Tony Bennett..this great guy voice's sounds great..but why is the right speaker sound more pronounced?..aah..the old Technics left tweeter did not work..why?..

Took the box home and off the grill, ups..the woofer dust cap did not look right, off then with the tweeter, the mid (it is a 3 ways system) and the crossover. Checked the tweeter with a multimeter,'s dead all right. Those cheapo crossover !, they use a very cheap bipolar electrolytic capacitor (small cylindrical thing). They have a limited life, and when it did went bad even the speaker protector can not do anything. There goes the culprit, and I have replaced it with two quality film capacitors, now you'll have extra 10-15 years of listening pleasures.

So, please check your 'expensive' JBL's, Bose's, Sony's, Phillipses, etc. If you see this kind of capacitor, replace them immediately with film type, the same value of uF and same or higher Voltage of course. Do this before your tweeter goes in to smoke, and if you planned to go the DIY way make sure the warranty time is out.

When I took off many parts of the speaker (it's an old Japan design), I have noticed that I have to use 2 types of screw drivers, found many types of screws, each different in size and form..what??..

In term of mechanical design, this is a BAD design practice. Too many parts, too many items, one too many tool, way to many part bins during assembly, storage, purchasing-inventory management..on and on..(you get the drift..).

I have counted 6 types, plus another 2 on the crossover assembly, oh yeah, another one on the speaker protection PCB in total : 9 types of screws. This is too expensive. Is Technics still around this day?

Thanks for reading