Posted on Saturday, 19th May 2012 by Auw Jimmy

Please go back here if you haven’t read the first article. On this second part, I’m about to create the potting ingredients to pot my Lundahl choke. I have several experimental ingredients, so some of them might not be exposed in detail as the result is still beyond my imagination.

One of important thing that we have to remember is beware of the chemical and its effect. Some of this chemical could be dangerous if exposed with fire. The solution is to use temperature controlled electric stove or for a ‘poor man’s tools’ – I would prefer a simple double boiler. You can use candles (note the ‘s’, means you need more candles to reach your needed temperature) or you can use gas based stove. FYI, double boiler would be safer (if you can’t get a temperature controlled stove) as the temperature mostly would not exceed 100 degrees Celcius.

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Tags: Alcohol, Choke, Double Boiler, Potting, Shellac, Wax
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Posted on Monday, 14th May 2012 by Auw Jimmy

It’s been a while since this idea came to my head few months back. Now it’s time to make it happens. As you might also know that Lundahl is one of the good transformer maker. They use their own C-Core most of the time for their production, included this Choke.

Though I believe they don’t have issue with their “open” design, some people prefer to have it potted to minimize any vibration possibility (included me). So here I come, a potted choke project with this Lundahl.

First problem came to me few weeks back was how to find appropriate enclosure to house this choke. Definitely not easy. Doing custom made housing would be my last resort. After spending few weeks searching, I found a chassis from Hammond which was quite OK for my purpose. I tried to contact nearest Lundahl agent which located on Malaysia (Octave) but they didn’t have it. I also planned to give a visit to Martin Electronics located in Singapore as they carried quite a lot of Hammond stuff, but unfortunately, I was so busy in other thing and have no schedule to fly to Singapore. And last resort, I gave an email to Chris (Partconnexion) and his assistant as usual quoted me with best pricing. Well, I hated to spend almost the same with my goods price for shipping, but got no choice this time. Canadian post is always too expensive for me

After the Hammond came few days ago, it’s time to start drilling…

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Tags: Choke, Lundahl, Potting, transformer
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Posted on Monday, 19th March 2012 by Auw Jimmy

As usual, local audio DIY group in Indonesia held a routine group meeting and gathering. This time, the topic is DAC. There were several contenders joined this session.

Below is the setup used on that session. CD Player was CEC. Preamp were solid state (Pumpkin-Shunty Balanced Preamp) and tube (Aikido). Power was Aleph J2 ‘clone’. Speaker was 3-way floorstander with Vifa drivers.

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Tags: AD1865, AKM, Bintaro, Blind Test, DAC, J2, Pumpkin-Shunty, TDA, Yaqin
Posted in DIY Audio, Indonesia | Comments (11)

Posted on Sunday, 4th March 2012 by Auw Jimmy

It comes upon a time when my DACT Stepped Attenuator needs a clean-up. Well, if you see below picture, the connectors are getting rusty. I could hear significant noise when changing the volume. Although some external cleaning spray has been used, but it seems they only solve the problem temporarily. I do need a serious overhaul on this stuff.

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Tags: DACT, Stepped Attenuator
Posted in Collectible Stuff, DIY Audio | Comments (4)

Posted on Sunday, 26th February 2012 by Auw Jimmy

I never ever think what is circular connector before – and what it’s all about. But when it comes upon a time when I decide to split my power supply from my preamp, then I start to think how to connect them.

Well, we have several options, but the most common one is by using a connector which commonly called circular or cylindrical connector. I would rather say it’s similar like a DIN connector, but with a lot of option in the size and pin counts.

Before, I plan to go with Amphenol Military Grade one (with extra protection in the harsh environment). But it’s quite difficult to find as my needs is minimum 4 pins @ 2 mm diameter at least. Almost a lot of online store doesn’t have any stock – even if they have, the price is quite high.

So eventually I find this one, Nanaboshi circular, at quite reasonable price and could fill up my requirements.

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Tags: Circular Connector, Nanaboshi
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Posted on Sunday, 26th February 2012 by Auw Jimmy

Indonesia High End Audio Club (IHEAC) arranges a ‘grand prix’ to encourage DIY community to build and show their best product. There will be several blind test and each session will have 3 winners with different points rewarded. At the end of the year, the highest point accumulated shall be the first winner, etc (just like F1 race which will have the winner at the end of season).

The first session was DAC, which quite interesting as not much DIY touched this part. Probably because it’s not too easy to play with digital circuit.

Not too much photos in this session as most of the contenders are similar (silver or black boring box, without any interesting part to be shown).

Below wass the main stage. We could see Vienna Acoustics Mozart Grand as main speaker.

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Tags: Blind Test, iheac, Indonesia
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Posted on Monday, 6th February 2012 by Auw Jimmy

This article, for most people, considered as ‘snake oil’ or made by ‘retarded audiophool guy’ (could be me). I just throw a little bit idea in this post, but feel free to try. During this stage, I will not share too many thing (still on experimental stage). But if you are interested to find out more, ‘MDI’ and ‘Pierre Johannet’ could be your next keywords at Google. Feel free to dig more.

At some parts, air is the most natural insulation, but has very low breakdown voltage. Although some people claim Teflon as the most superior insulation with very high breakdown voltage, but at some point, I would rate Teflon as slightly analytical sounding. In order to have ‘just enough’ protection and ‘good sounding application’, we can go with things just similar spec with air (a little bit better, I think). Well, name it cotton, paper, natural fiber, silk, etc. Feel free to experiment with them.

For the conductor, off course, pure material is a must. Either pure copper or pure silver. I would choose for pure silver whenever possible (I mean, whenever I can afford it).

As we are picking an insulation with lower breakdown voltage, then it also means lower protection from environment outside. Then another protection is a must. After several experiments, I come up with a block of wood with specific distance to separate or isolate them (the cables in this context). Sometime I also combine with a tinned copper rod as separator or insulator to prevent oxidation.

The wood block was made by my good friend, Mr. AS from somewhere around West Java, Indonesia. It was a very nice wood block with very accurate cut (machine made for sure). Thanks a lot for such a good work, bro!

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Tags: Cable, Copper, MDI, Pierre Johannet, silver
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Posted on Tuesday, 24th January 2012 by Auw Jimmy

It’s been a while since my last capacitor comparison review was done. Not much changes actually (not much new ‘interesting’ products also I think). But I was quite tempted to try the Alexander series from Duelund. The reason was simple, it’s quite affordable but having Duelund popularity on it. We’ll see if it’s worth to try.

As usual, I put one of my favorite ‘affordable’ reference capacitor, the Jensen Paper Tube and the ‘premium’ reference capacitor, the Duelund CAST Cu. I kept my ‘ultimate’ reference capacitor, the Duelund CAST Ag, as this was a different beast.

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Tags: Alexander, CAST Cu, Duelund, ELMA, jensen, mundorf
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Posted on Saturday, 7th January 2012 by Auw Jimmy

After the Part I has been done, now I continue to the Part II. On this 2nd part, I will see what’s wrong with the Marantz PM400AVK.

Simple testing method is to try it on other speaker. Initial diagnosis is the volume control problem, as I could hear some cracking and intermittent no sound on the speaker. But sometime the problem could be solved after turning the volume up and down. Definitely, initial problem is on the volume control. So let’s take a look inside.

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Tags: ALPS, Capacitor, Fake Capacitor, Marantz, potentiometer
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Posted on Wednesday, 4th January 2012 by Auw Jimmy

If you have read this previous article, probably you got my point when reading this one. Now, I’m doing the modification for the speaker. After several serious examination (well, you know me, I can’t be more serious than this time), it seems that there is no hope for the tweeter. So let’s find a good replacement. After googling around for several hours, I stick to the Vifa XT25SC90 tweeter. I use the ‘older’ brother XT25TG30 on my other DIY speaker and quite convinced with its sonic quality (despite its poor off axis performance). Price wise, you can get a pair less than $50. What a bargain?

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Tags: Bennic, Cable, inductor, Mission 762, Siemens, speaker, Tweeter, XT25
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Posted on Monday, 2nd January 2012 by Auw Jimmy

My wife knows and supports my hobby in audio. I think she even knows almost all of my expenses. Well, ‘almost’ means maybe there are some that she doesn’t care or aware of – not my intention to hide from her .

Once upon a time, when we were on her mother’s living room, I stumbled upon an audio system used there. It was quite old and sounded ‘ultimately’ bad. She jokingly asked me how do I rate this system. Honestly I said, maybe around 20 from 100 scale. Well, it’s true. Even maybe 20 was still slightly over rated. Then she challenged to improve it. After checking them for few minutes, I decided to give further examination as the condition was ‘terrible’. OK, I could bring this home for some new year’s fun. Then the adventure begun…

Now, let’s start with the speaker. The speaker is Mission 762. Quite good on its era (20 years back). But now, it sounds so bad. The woofer seems fine, but the tweeter I think already running out of his life. Too much noises and ‘too smooth’ (means no treble or detail) .

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Tags: Marantz PM400AVK, Marantz Receiver, Mission 762, Mission Speaker
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Posted on Monday, 26th December 2011 by Auw Jimmy

For most of my soldering life, I still use what we call as ‘Flux’ or ‘Soldering Paste’ (or also known as ‘Lotfett’). Although some people say that the use of Flux for soldering is for newbie work , but I don’t really care actually. What I do want is a perfect soldering quality.

Below is the frequently used Flux. It’s cheap (indeed, very cheap) and enough for most of us. I bought this long-long time ago and never can finish it although has been used hundred (if not thousand) times.

But few weeks ago, I started to think a better replacement. I saw a Rosin Flux made by Cardas (to be honest, not many brand makes such Flux any longer as most of the newer solder already incorporates Flux inside to simplify our soldering job). But again, in most of the time, a separate Flux still needed. As the price was quite reasonable (though still multiple times compared to the Lotfett), I decided to grab one.

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Tags: Cardas, lotfett, rosin flux, soldering paste
Posted in DIY Audio, Personal | Comments (11)