Posted on Saturday, 26th July 2008 by Jimmy Auw

After Elna, BlackGate, and M-Lytic, now it’s time for the Obbligato. My order just arrived yesterday. I bought three types of Obbligato available on the market.

The picture above is the Obbligato Copper Case Aluminum Film Caps. The case is solid copper with soldered copper lead out wires and individually wrapped. The aluminum film is imported from Germany. All measure very close to rated value, max 5% but typically 1-2%. Wound tight, no voids gives a very transparent, smooth sound.

This capacitors looked beautiful with the solid copper case. Looked expensive, heavy, and well designed capacitors.

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Posted on Wednesday, 23rd July 2008 by Jimmy Auw

Yesterday, another component arrived. This is one of the most important component for my B+ power supply. Welcome the Mundorf M-Lytic High Voltage “Special Custom Edition” 560uF/400V.

This special capacitor made by well known high end capacitor manufacturer, Mundorf from Germany, is probably one perfect candidate to replace the Black Gate era. Well, I just can’t afford the Black Gate WKZ, so this M-Lytic should be a perfect replacement. I might try the Unlytic also someday… If I can afford it

Enjoy the zoomed detailed version of the capacitor below.

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Posted on Monday, 14th July 2008 by Jimmy Auw

Usually, I never care about the theory behind all of my DIY project. Just plug it, hear it, like it, and finish it. But now, due to some reason (though somehow I also don’t know the exact reason why), I want to do it from scratch and want to be backed-up with some theory and calculation behind it.

My next project (again could be the last one) is a high end power supply for my Aikido pre-amplifier. I think I’ve mentioned about this project before.

This is the first part discussing about the theory behind my next DIY project (about the tube rectifier IFRM and capacitor/choke input). Next part will come soon.

Prologue:
I’m considering the usage of tube rectifier (I have Svetlana 5U3C or 5U4-GB on hand). So far, I only used to play with silicone rectifier where I don’t have to care about the size of filtering capacitor. Now, with tube rectifier, I have to learn the theory back again.

Tube rectifier, in this case my 5U3C or 5U4-GB, has only 1 Ampere of IFRM (Repetitive Peak Voltage Current) and 99 Ampere of IFSM (Peak Forward Surge Current). FYI, most silicone rectifier like IN4007 has both 99 Ampere of IFRM and IFSM. So any size of capacitor will be ok for this silicone rectifier (it won’t stress the rectifier, 99 Ampere is a huge number!).

The low capacity of IFRM of the tube rectifier makes the usage of big first capacitor is impossible. If you use big size of capacitor on the first stage after the rectifier, then this capacitor will stress the rectifier due to high load of current. Bigger capacitor will pull a lot of current. If this amount of current is bigger than the rectifier limitation (IFRM), then you probably could damage the rectifier. Please check the rectifier datasheet before you plug any big size capacitor (over 30uF) as your first filtering.

As you can see from the picture above (I use PSU Designer II from Duncan). With a too big first capacitor (errrr, 220uF is not that big, right?), you will put too much stress on the rectifier exceeding its IFRM. The big capacitor will need a big current to charge itself. If it exceeds your rectifier maximum IFRM value, then it may cause trouble. The result? I don’t think you want to know (or see) the effect

But I need a big capacitor to give smoother filtering… Then continue reading

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Tags: DIY-Audio, power supply, Pre Amplifier, theory
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Posted on Monday, 7th July 2008 by Jimmy Auw

After here and here, well seems not enough, I have ordered some more components for my next DIY project. Just arrive today. The target is clear. This could be my last so should be my best DIY project. So, I’m gonna be serious… gotta be…

A bunch of Elna Silmic, around 16.000+ uF each channel for heater power supply? Are you serious, Jimmy?

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Tags: Capacitor, DIY-Audio, power supply, resistor
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Posted on Sunday, 6th July 2008 by Jimmy Auw

My custom power transformers have just arrived. Like on my previous post, I plan to use 4 power transformer for my next Aikido project (two Heaters and two High Voltage). So here is the stuff

The first line above is the High Voltage power transformer (primary on 220V, secondary on 200V, 220V, 230V, 250V, 5V , and 7.5V). I have extra heater’s secondary in case I don’t want to use the additional transformer. The High Voltage itself rated at 200mA, while the 5V/7.5V rated at 3A.

The second line above is the Heater power transformer (primary on 220V, secondary at 5 and 7.5V). Rated at 3A. So, I completely separate the Heater and High Voltage power transformer, resulted in 4 power transformer for this project. (more…)

Tags: B+ supply, DIY-Audio, heater supply, transformer
Posted in Collectible Stuff, Indonesia, Personal | Comments (7)

Posted on Sunday, 6th July 2008 by Jimmy Auw

The time has come… Saturday, 6 July 2008… The Aikido Blind Test session at Tubelover, South Jakarta, Indonesia. Total we have 11 contenders today. All with John Broskie Aikido Pre-Amplifier design. Some use the original PCB ordered from here and some prefer their own point-to-point design. Various tubes are here, small 9 pin tubes, Octal, and also the miniature like 6111WA and 6021.

Here is some snapshot from the event.

We use the Jadis Defy 7 Push Pull Power Amplifier rated around 100 Watts RMS (twelve 6550 tubes). The speaker is Tannoy Stirling with Fostex Super Tweeter. The CD Player is Audio Research CD3 MkII.

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Tags: Blind Test, BT, DIY-Audio, tube
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