Posted on Sunday, 30th January 2011 by Auw Jimmy

Indonesia High End Audio Club or in short, IHEAC, held an blind test (or maybe I would prefer to call them as blind scoring) for tube pre-amp. The session was  started on the afternoon, around 11am. Some equipment used shown below.

We can see some stuff like Quadral Platinum M4 speaker, Consonance Droplet CD Player, Air Tight Reference Pre-Amp ATC-3, and KT88 tube amplifier (I believe in Push Pull configuration).

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Tags: Blind Test, iheac, pre amp, Pre Amplifier, preamplifier
Posted in DIY Audio, Indonesia | Comments (3)

Posted on Sunday, 7th December 2008 by Auw Jimmy

Last week, located at Audio Lifestyle Magazine office (also known as TubeLover showroom), held a Pre Amplifier Blind Test Session. If I could recall my brain correctly, we have 38 contenders, from Aikido 6SN7 Pre Amp, to antique #26/#27 Pre Amp. Well it was so nice and crowded session, from 10 am to 10 pm. Over 12 hours, 8 preliminary sessions (5 Pre Amp each) + 1 final session. I was sooo tired to judge in all those sessions (except session III where I need to receive some phone calls). We have 5 judges and some audience to pick favorite/people’s choice Pre Amp.

Enjoy some pics here. So many Pre Amp, so many design! The equipments was Consonance CD Player 2.2, Jadis Defy 7, and Tannoy Stirling full range speaker (with extra Fostex super tweeter).

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Tags: Audio, Blind Test, pre amp, Pre Amplifier, tube
Posted in DIY Audio | Comments (7)

Posted on Monday, 14th July 2008 by Auw Jimmy

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
Posted in DIY Audio, Personal | Comments (0)

Posted on Monday, 23rd June 2008 by Auw Jimmy

Well, this is a surprise news for me (at first). A “Made in America” PCB? Seriously?

Few months ago, my friend introduced me to TubeCAD (and finally led me to John Broskie). Actually, I knew his TubeCAD Journal and even his famous TubeCAD software 1-2 years ago (or more). But at that time, I didn’t have any interest on such technical things (like Broskie’s journals). Until finally, I heard his Aikido pre-amplifier and quite stunned how come a simple pre-amplifier (with cheap components) could lead into magical sound! Then I changed my mind and started to read some of Mr. Broskie’s journal.

My interest in some of his articles led me into a personal communications via e-mail (well, I do enjoy the modern technology, I wonder if I should send him an ordinary air mail to ask about his article – it will take years before I can get myself answered! With e-mail, within a night – due to different time zone, almost all of my questions could get the answers).

Finally, I decided to order his Aikido 9pin Mono PCB. John sent the package via express mail. It arrived around 2 days but due to custom issue, I accepted in around 5-6 days. Still quite a fast delivery

Here is the PCB. Dual sides, plated-through 2 oz copper traces. Don’t forget that both sides are silk-screened.

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Tags: 9pin, Aikido, DIY-Audio, PCB, Pre Amplifier, tube
Posted in Collectible Stuff, Personal | Comments (9)