Washing Machine and Mosquito Hitter

I'm feeling like writing today :) but not yet about DIY audio though he he. Recently my wife complaining about our washing machine, the centrifuge just don't work. This machine is less than 1 year old. Here it is.

Opening the front cover reveals this, hmm...another plastic failure case..man....just hire me to do your design :), or pay me to check your design and products...

The broken thing is safety switch housed in plastic casing. When the lid is open the centrifuge stops. Consequently when this switch is broken you can not turn on the centrifuge, since it is a 'normally closed' switch. What went wrong? well, the switch housing is kind of poorly designed, small footprint of attachment and cross sectional area, with lots small and sharp notch. Perfect recipes for failures waiting to happen.

I 

Here is another details of the switch housing. Blue marker indicates cracks that originated from sharp notch.

I reckon only about 2mm X 15 mm square of area that must withstand cantilevered housing of 60mm long. If the force required to close the hard copper leaf switch is 0.1kg then the root suffers 0.1kg X 60mm of bending load plus 0.1kg vertical load reaction, small loadings? maybe..but that small loads repeated over 200 times and with that sharp notch? exactly!...for quick fix I just hardwired  & isolates the leads...at least the centrifuge works now, without the usual 'safety' feature though :)..


Another product  I've observed is the famous mosquito hitter. We have used and throw away many of them, they're cheap and short lived :). The green one here last a month. Most annoying is that the switch of the lamp is on the wrong side, so when you put it on that side, you will unintentionally switch the lamp on, emptying the battery...yes the mosquito's is laughing at  me :)...

Now we got another one, sturdier, better looking and ergonomics, very powerful, until I got that high voltage - low current power right on my leg..I screamed the **** off...yes the mosquito's are laughing even more louder ...sigh...ze power never the same again..absorbed by my leg I think :)

So in one evening with nothing to do, I opened both hitters..1350VDC mylar capacitor?..no wonder :)..

and 2 A3 rechargeable battery...now I know how NOT to buy another hitters...:)...watch out you mosquito's...!!

CD Jewel Case, CD "perfect sound forever" vs good old Vinyl

I guess when it come to audio format I'm one of the lucky ones. During my childhood I have listen to old but very good sounding tube radios and mono's black vinyl in 78 and 45 rpm. Later on my dad bought a Lenco turntable and bunch of  33rpm black discs, Paul Mauriat, Frank Sinatra, Demis Rousos, Nana Mouskouri that I still remembered, oh yes and Koes Plus  :).

Then comes the bulky Philips Compact Cassete and the final compact cassete. Yea, one of my cousin prefer Teac tapes reel while I played with cassetes and vinyl. . My kids and many younger generations knows only MP3's, Ipods and for sure never heard of Walkman and Discman either.

It is now about 30 years after CD introduction. There were Laser Disc, Beta, VHS, S-VHS, DVD's in between. SACD, blueray, MP3, AAC, Flac, and bunch of other 'transferable' digital formats. Me? I prefer to hit my brake soon. It's CD, Vinyl and one of those 'bit to bit perfect'  digital format out there.

When the silver disc first came out I remembered one of the marketing hypes - "perfect sound forever", after 30 years let us see what happened to my old -early CD collection and of course similar aged vinyl ones.

But allow me to whine for a while :), the jewel case of CD's. For me it is irritating. The hinge breaks off very easy, it happened just after every time you buy new one. This is a bad design case for me and sure for others and after very long time no one cares. They even selling empty cases :). What is going on?

 

Hinge of the case is the most heavily loaded section. Although the case is made of though polycarbonate (and later, cheaper polystyrene) there is one problem here, stress concentration. Because of the geometry around the hinge the stress there is much higher than in other area. The location is at the root of the hinge. There is a sharp corner and to make things even worse, people add ridges there, further weakening already flimsy thing.
The stress there is at least 3 times higher so no polycarbonate and polystyrene is tough enough. First cracks will develop and then.....

Actually it can be prevented by adding a stress relieving geometry, such as adding a round in the corner. Mysteriously this never happened, maybe it's good to have many broken jewel cases for the producer

Luckily in recent times there are several better CD packaging in the market, but I think this new packaging is what I called 'cost driven' designed. Just because world oil price is hiking- so virgin plastic pellets are more expensive, particularly the transparent ones that the music producer need to show off the cover. Here are some of them. I loved the paper ones. Never breaks , have a nice booklet that do not need to take out and put back again :) and makes little noise when it falling down...

So there is my whining and now what happen with the perfect sound forever ? I have here one of the GRP CD, Chick Corea Electric Band (1986). I did nothing wrong except playing it occasionally and most of the years just sitting in the box. Some years back I started to saw holes through the disk, and the holes are getting bigger and more holes appears...so much for a perfect sound forever.

Another CD, Chick Corea ' Light Years' (1987) album stays fine, just as fine as the vinyl one below. I guess it depend how lucky you are with your CD's. I have many more CD's damaged by it self than vinyl damaged by my worn needle. I do have some scratched and warped vinyl. But the vinyl do not change it condition during all that years!. At most finger prints gets moulded and fungi  growing in it and after washing the disk it plays perfect as it gets. I do have some pristine old CD as well after storing it more that 20 years.

So, does CD gives perfect sound forever? No, I don't think so, Vinyl is? no it's not either but it's closer ;)). Thanks for reading


in the pipeline :
my 'new' TDA1541A NOS DAC, single, parallel, reviewed together with on board DAC and 8x NOS TDA1543 DAC

Entry to wonderful world of tube audio

When we first think about this 'ancient' amplifying device, at least 2 things comes into beginners mind, lethal high voltages and expensive tubes. Both of them drives many first time DIYer away. I must admit it's not easy for most of us to start with glowing tubes after the comfort of making a Gainclone or chip amp.

Well there is an answer in this, a cheap tube and low voltage supply or what we call as B+. To add some warmth in clinical sound produced by CD player and our gainclone, a topology called buffer is all we needed. Buffer does not amplify, it's just make driving your amp easier by providing better impedance matching, also the gain of this buffer is actually less than 1.

About a year ago Mr. Arif from Tubelover introduces tube buffered Gainclone, he gave us the schematic during DIY audio Blind Test gathering at Mr. Didik W.  home. There are high voltage tubes that can sound very nice in low voltage, such as 6DJ8, 12AU7, and the Russian 6N1P. This 6N1P is the cheapest and widely available so I started to think about this buffer when friends at Solfegio Forum are looking for cheap and 'safe' tube gear. So here are the story.

Schematic from Mr. Arif (many thanks for sharing pak !) it is his hand writing :)

My translation of the schematic and board layout

But before I built the buffer I would like to see how it's perform by simulating it, I want to know what is the 'harmonic distortion' figure say at 1kHz sinusoidal input signal. Fisrt the input-output figure,

Traces : green is input signal 2Vpeak -peak (just like most CD-DVD player output), yellow is the buffer output, note that it's not 2Vpp anymore. Now let's see the harmonics of the same signals,

Green is the input signal, yellow is the buffer output. Clearly the tube does something to the original signal, it's adding harmonic peaks at 2kHz (even harmonic), 3kHz (odd), 4kHz (even) , 5Khz (odd) and 6kHz (even).

What does this means, it's means that we get distortion on the output. Notice the higher 2nd harmonic at 2kHz relative to the other, people says that this is the 'nice' sounded even order distortion, just like what happen in nature, so we tend to call it pleasant sounding. The not so pleasant sound are the odd harmonics.

So simulation show quite promising figures. Will the simulation results reflected to real build? I don't know so let's build this buffer and fast forward to the final one after days of tweaking :)

My buffer is using 6N1P tube, 6.3VAC heater, why tweaking? after initial listening using a DVD player it's really needed that, the buffer sounded mediocre but it have potentials. First the output capacitor, final value is 6.6uF, then power supply electrolytic, also the type and brand of the drop resistor for heater (from 12VAC) has significant influence to sound.

I did tweaking after hearing and 'measuring' the DVD with and without buffer. I've found a nice software called AudioDiffMaker , its do the comparison of reference signal against a 'tweaked' signal. In this case I compared direct DVD out to Buffer out. I did 2 signals, a 500Hz 0dB sinusoidal from my Denon test CD, and music signal. Here are the screen shots.

AudioDiffMaker form

500Hz direct DVD out

500Hz Buffer out

500Hz Difference DVD-Buffer

Here we see again the harmonics of 500Hz signal, what to understand? first check out 2 small peaks after large 500Hz peak. Direct from DVD shows 2 small peaks upwards, out of buffer 2 small peaks one upward (even 2nd harmonic) and the next downward (odd 'bad' harmonic), so at least the tube somehow alters the peaks. As for the rest the AudioDiffMaker sort out the difference and in term of signal it is very large difference and you can hear it!.

 I did another signal, this time a real music signal. here are the differences, and yes you can hear them as well

the form

the difference, both channel

So finally Bill Waslo, the developer of AudioDiffMaker gave us the tool to check whether you have 'improved' your system using new cable or 'voodoo' tweaks :). As for me, the software will not tell you how good the sound is and I have tweaked my buffer to a level that I missed something when I'm not using it :) some day I'll measure it again with AudioDiffMaker.

Check here for details & friends building their first tube buffer. Thanks Bill, thanks pak Arif. And to my friends..built it, tweak it and enjoy it

Cheers

DIY Audio pot pourri 2 : Woody film capacitor

Long time ago I came across a Dutch web site explaining electrolyte capacitor modification. Recently a fellow (senior) DIYer Mr. Paul also have done similar mod with paper in oil capacitor, DHT Rob reports improvements on replacing aluminum can with wood filled with beeswax. Also mixed results from Pak Paul from what I've heard.

A longtime DIYer friend said that you'll get sound improvement just by lightly sanding the caps. Nothing but subjective result analysis though, but I've found a freeware just for that, detecting difference of the same music signals one as a reference- the other may be through a different cable - more about this in my next post.

I've got 4 Solen MKP capacitors belong to a friend ( Hi pak Johny..) so I'll give a shot. I've made mahogany tubes, soft wood cover. I've broken in the caps before for  very long time on the bench. So here are they. The tools are small PCB drill for the caps leads through the soft wood cover and a tweezer. This soft wood is press fitted to the mahogany tube.

I still have some space left in the tube, so the Solens are wrapped with the tissue and pressed in to the tube. The input and output leads are marked, they do make sound difference how you connect them even the Solens are non polar.

Wrap like this, plenty of excess on both ends, they can be removed easily.

Excess tissue paper removed with tweezer

 

There you go!. A pair of Woody Solen :). Notice that the leads are not centered. Good idea if you marked them before drilling

 

I did a comparison in my Sony CDP -M75 - looks awesome!. There are difference in sound - not much but the Woody tend to sounds smoother. Definitely better than the original CDP ouput (with Elna Duorex 2 electrolytes).

 

 Here my  friend Aphinx using the Woody for input coupling on his D class amp. Originally his input coupling was the Russian MBM 1uF we found the woody sounds better. Below the Woody tested against Ampohm MKP, he likes the Ampohm better . 

  

So there are differences in sounds when you do this kind of modification, whether the sound is better or worst is another matter. Any explanation on this phenomenon? Let me guess, first the skin effect - greatly influenced by surrounding material or dielectric- nowadays 'we' prefer natural materials - hence the the sanding, beeswax, natural fibre like wood, cotton, silk and paper. Silk? I think one electrolyte maker used it on Elna Silmic...

Secondly vibration - with tight clamping the caps are protected from it. Lynn Olson told stories about 'microphony' effect of vibrated capacitor - it wasn't pretty picture - he said . I believe them because I've heard the mod my self. My Spica TC-50 crossover is placed outboard , guess what? the caps vibrates like crazy there. So, at the very least we should tie, damped and fixed our caps very well. Good luck !

DIY Audio pot pourri 1 : Spica TC50 crossover tweak

During several months I've carried out many small audio tweaks. Not full blown projects though but I think it's maybe quite interesting sharing them :).

First is my Spica crossover tweak, continuing effort IMO still necessary to replace those old ECI lytics. This time I like to tackle the high frequency section. On September 2002 the Spica designer John Bau was interviewed by  Enjoy the Music.com and asked what to do to improve his Spica, one of his answer is to change all the electrolytic caps to Film.

So here are the pics, some caps, made some 'risers' for easy soldering and quick caps change.

first on the board are Wima MKC 4.7uF, Green Nichicon Muse's 10+22uF, Black Nichicon BP-S 4.7uF. Left them for 3 days about 12 hours on play, sound? me not like :). So instead of waiting for another 3 days I just pick - place - listen - change. An advantage of working with broken - in and old caps...

 

The Wima MKC can stay, it sounds well for coupling capacitor on my CDP-M75, so next on the board is 0.1uF K42y Paper in oil bypassed the BP-S, still not liked it, then I went to my garage pick some big 22uF Solen MKP - the last pair I have, this in parallel with poor small 10uF green Nichicon Muse, sit and listen...man!..the bass is like I never heard out of this Spica..I wonder though..I'm working here in the high freq region and I get that bass?..well the Solen and the Wima stays!.

Now the job is much easier, that what I've thought and I was wrong. I got better bass & high, same and maybe better staging, but some tracks still give sibilance. Swapping the BP-S to Evox MMK did not help, same with 'old' Yellow Rubycon.

The last 4.7uF film cap I have is a pair of el-cheapo yellow Audiophiler..yuck.., nonetheless I've soldered them and ...its sounds ok, no, they sounds quite well indeed..and  totally acceptable to me, much better than the Evox.. So the Audiophiler stays! After 2 months listening I tend to let this setup freezed and change the 10uF Muse to MKP and maybe another Wima MKC replacing the Audiophiler, I miss the high notes timbre of acoustic piano sometime. 

My lessons here, tweaking the sound for Mid is very difficult, many times proven cheap parts perform well in combination with other. Thanks again for reading guys..

In the pipeline : 

-Part 2 :  film cap gets woody jacket..

-Tubelover 6N1P tube buffer in depth..

Electric Fan, MMC holder

Now, some design cases recently I've observed as always - at home. A memory card holder and an electric fan. Nowadays you can barely escape from plastics, everything we use almost certain contains plastics - one form or another. Let us begin with another well executed design first.

A plastic holder made from PP of polypropylene. Very nice, compact and functional. This one comes with my digital camera. It's function is to hold a pair of memory cards, MMC. Lets try to see how such a design took place. 

First is surely the design requirements to function. It needs to hold MMC's, must be transparent or a bit see through so that we can see what cards inside, light, very cheap, not easily breaks, the card must be secure enough - not falling down by itself, easy to use etc.  These are just wordings, no design concept or design sketching whatsoever. 

Now comes the Task. Task comes after function. Tasks are whatever you need in the design in order your design to function properly, still no real design yet at this stage :).

To cut the story short, take one of the design requirement, lets say " easy to use", now let see the 'design' below. What features coming from the 'task' of the holder supporting this requirement?. 

 

There are several, as this 'easy to use' requirement is the most vague and hard to implement. We can see small recesses on both side of  the holder. Curved recesses on the sides are for your, say left hand thumb and middle finger. Also on the top where you can pull the card inside using your thumb and index finger...smart eh..?. Last thing you want is to be able to insert a card and can not pull it out....

What else?  yup, easy to use often means easy fabrication as well. Hence the two parts, mate both half, press clicks..you're done. Why not one part? well it can but the metal mold will not run very long. Lots of small thin 'cores'. Easy to break with high molten plastic pressure and you production will be ruined.
See small slit and a bulb on the right sides? It is an integrated spring, it task is to push the card to the left wall. This creates enough friction, preventing the card from falling down..another smart design.

Such a simple thing like this are full of hidden smarties, which greatly contributed by systematic thinking in terms of Function and Task. Most of innovations are made by thinking hard this way, rather than 'eureka' thing..., smart!.

Now, a saying that says A Chain is as Strong as the Weakest Link is really well said. Look at this beautiful small electric fan. Same brand as my problem rice cooker. Their products have the bad habit of early broken up..sigh..watch out!.

All the parts, plenty of them laboriously made. The styling is not bad either. The fan cost less that $15, last less than 5 month just because of ..weakest link!. see below.

The weakest link in this case is the transformer wire. It gets hot, even there is thermal protector- the wires are broken somewhere in the winding. So all the labor, effort and resources just wasted. Really? not much though.

Buying this fan keeps the factory workers get their salaries. The seller get profit and can take care of their family. What about I'm throwing this fan in garbage bin then?
Hmmm..there comes the most environmentally friendly job in the world...the Recycling Man!. Yes they live from our garbage, they will sort and pick all the plastics and metals for further recycling. They get money paid for that. To me, the Recycling Man is my Super Man!.

What do you get? Next time you buy new product please don't be surprised. 80% of that product was indeed once your garbage :))
And what did I get? just a lousy transformer bobbin with 30ish gauge enameled copper wire from which I planned to make something like this see below and several hours of Audiophile-foolishness fun :). Thanks to broken fan and Bud Purvine and his DIYAudio postings on ground side electrons..what ever that means..

This is the first time I can relates design stuff with DIY audio thing. Thanks for reading my foolishness.

TDA1541A , more than I can handle!

Actually I've planned to write about yet another good design bad design thing, this in waiting my mood to finish-tweaking my Spica TC50.
During visit to my audio part supplier friend just before a long Eid el Fitr holiday,  I in all a sudden being blessed by a chance of trying out a bunch of the legendary TDA1541A DAC chips from Philips, not one or three pieces, but 4 tubes with about 8 to 13 chips each!. plus a pair of TDA1541 (non "A")..More than I can handle..so I've postponed the Spica tweak and design thing...

My friend is just one out of many victims around the world of TDA1541A frenzy that still on going even today!. It's the Fake or Genuine TDA1541A debacle that started out around 2004. This chip is so high in demand that some people just make  fake ones and sells them. Just read this thread about it in DIYAudio.com. My friend have tested the chip randomly some 6 years earlier, none working he said..

Being a TDA1541 fanatic (see my Sony CDP950 tweak stories starting here ) I took the challenge of testing all 4 tubes, may be, just maybe I can get one or two working chip. As a positive thinking guy I assume there is always some good thing out of even bad guy!. I even told my friend if I can find a good chip I will let him know. So here is the chips, my story & the pics..enjoy!

The tubes, yes in the 90's and early 2000's Philips made the chips in Taiwan, many says even with better production process than in Eindhoven Holland. The highest grade, the TDA1541A/S2 (so called 'double crown') is made in Taiwan.

Testing all the chips here in my salvaged Non Oversampled Sony CDP-M75 with Sennheiser PX100 headphone. This player was totally wrecked and non functional. I've got it from a good friend (thanks mas Yuda!). I planned to take out the DAC only for spare and piggy bagged to DAC in my Lampized Sony CDP950 for higher current output. It turned out that I have the luck to bring it to life :) so here we go..


After testing the chip halfway? Guess what?.. there are 5 chips or so that completely working! But beware!, and I know from the DIYAudio thread later on, there are some chip that can blow your CDP!. Here are the 'test result 'modes' :

1. the CDP just doesn't want to turn on, no display at all when powered up - the chip felt cold and is busted
2. as above but the chip felt warm- busted as well
3. the CDP and the display turns on, the disk spins and ...HEY..it worked!....yippee!
4. the CDP turns on, the display also, the disk spins, chip is very hot and I can hear some music-heavily distorted and interrupted often..then I heard loud DC signal through my daughter's  PX100..frantically  switching off the player.......what... was.... THAT??..

Tried to turn on the player no luck...sigh...yep..sometime you gains..and other time you just loose..within a fraction of a second! This 'mode 4' is by far very dangerous. What I did was repeatedly switching the player on and off during this mode 4, a big No-No, learned later.

After checking the M75 for supply voltages on DAC pins, I found that pin 15 reads -34VDC..woow..it should be -14.9 or so... Luckily the other day I got schematic from Mr. Jeffry, thanks Pak!..read them, testing some components & yes one transistor is surely went busted.

Late in the evening and no electronic shop open for sure, I just browsed my old PCB's junk collection, looking for equivalent replacement, yup, found a better equivalent, 2SB734 in place of the fried 2SA1015. Fit the B734..aah..yes..the player worked again, so I continue testing, until my left hand thumb felt numb putting and removing those 28 legged little monsters...this time I'm very careful, no more switching in on and off again. No display- no disk spin -the chip is simply busted, and yes I recalled another 3 or so chips with 'mode 4'..

At the end of this tense testing session I can smile, BIG TIME :)...the TDA1541 non A worked very well, and hmmm let just say ~20% out of 50 TDA1541A chips are working too. My positive thinking and all the effort paid off well...the harvest? here are they..:)

My conclusions are that these chips were : original and working well (mode 3), the original damaged-rejected ones (mode 4) , original totally damaged rejected ones (mode 2) and the rest is just plain fakes (mode 1)

Me and my friend strokes a win-win deal. I think I'm getting closer to my dream, a dedicated DAC......so much about these and our audiophiles earthly needs...sigh..., thanks for reading my friend..