Posted on Sunday, 22nd November 2009 by Jimmy Auw

I ordered custom made transformer to replace my old Aikido Pre-Amp transformer. Before, I rarely ordered a “finished” transformer (but prefer doing DIY one with my colleague). But now I’m thinking to try a “proven good” transformer (and considering doing some comparison of its effect).

Finally it’s done. The transformer consisted of few secondaries, to supply my main high voltage, the rectifier, and the tubes.

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Tags: Aikido, preamp, transformer
Posted in DIY Audio | Comments (4)

Posted on Saturday, 26th September 2009 by Jimmy Auw

It’s a weekend holiday and it’s time to scratch my laziness and doing some audio DIY mods. This time, I will try a capacitor from Jensen, the 4-Pole Electrolytic.

What makes it different from standard electrolytic? Well, it has 4 poles instead of 2 of standard electrolytic (that’s why they call it Jensen 4-Pole capacitor - I wonder why 4-Pole instead of 4-Poles?) But that’s simply out of our discussion here.

Again another question, why it has 4 Poles instead of 2? Keep reading.

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Tags: Aikido, Choke, jensen, power supply
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Posted on Wednesday, 23rd September 2009 by Jimmy Auw

I dig my parts bin and found some resistor values which I needed to upgrade my Aikido. I used three brands here, Riken RMG “Metal Film”, Shinkoh “Tantalum”, and Kiwame “Carbon Film”.

Lets fire up the soldering iron

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Tags: Aikido, DACT, resistor
Posted in DIY Audio | Comments (6)

Posted on Sunday, 6th September 2009 by Jimmy Auw

Yes, you might call me crazy! A Teflon VCap TFTF on Power Supply section?

If I need to make myself clear, this 0.47uF/600VDC VCap TFTF Teflon capacitor will cost you around US$ 150 each (depends on quantity). So we will spend near US$ 300 only for two VCap TFTF here!!!

And eventually, you will ask why do I put those caps there? Actually this is an “accident”. I bought those VCap few months ago, but it just didn’t match right with my current system (it prefers Duelund CAST PIO) - check the article here, here, and here. So what should I do with them?

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Tags: Aikido, power supply, preamp, VCap
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Posted on Sunday, 23rd August 2009 by Jimmy Auw

Never ending tweaks and mods? Yes I think so. Actually, my Aikido Pre-Amp already sounds good. But as a DIY, I think the journey never ends. Tomorrow always comes with another mods. After completing the PSU mods with Mundorf MCap Supreme 3.3 uF/800VDC and ASC X386S 40 uF/440 VAC here, I decide to go further with some other components.

First, I still hear small hum. This is mainly caused by the Filament/Heater Center Tap of my DIY transformer is not exactly on the center. So the 1/4 B+ isn’t injected on the correct Center Tap position. The only solution is to create a Virtual Center Tap with a pair of 100 Ohm resistor. I use 100 Ohm 5W Kiwame. Some people may say that you can use any cheap resistor for this purpose, but I always choose the best price/performance. At US$ 2 each, Kiwame fits this job perfectly. Make sure you use an accurate resistor (metal film should fit best, carbon film also ok).

I fire up my Aikido and ta-da… no more hum, even when my ear next to the speaker! But I need to confirm later with high-gain amplifier. With a normal/standard gain amplifier, the hum is usually less noticeable.

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Tags: Aikido, DIY Audio, Duelund, Kiwame, mundorf, preamp
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Posted on Monday, 17th August 2009 by Jimmy Auw

I just change my old “Aruki” Korean oil-can capacitor to ASC and Mundorf MCap Supreme. The configuration before is 60 uF and 40 uF Aruki Capacitor, now changed to 3.3 uF MCap Supreme and 40 uF ASC X386s.

The effect? The mid and high are getting more liquid. Background is even darker, with better separation and richer timbre. No surprise some people love the film and oil capacitor on the Power Supply section, and this MCap + ASC combination also proves such theory.

For cheaper solution, I usually go with Solen or SCR.

Tags: Aikido, ASC, mundorf
Posted in DIY Audio | Comments (1)

Posted on Saturday, 15th August 2009 by Jimmy Auw

Still remember my Aikido project? Until now, I’m still using Octal socket (since most of my rectifiers are Octal based, like 5U4, GZ37, etc).  Few weeks ago, I was poisoned with RGN Rectifier. Well, I knew this tube for long time, but just that time was poisoned badly. Have no choice, got to get one at eBay.

How do I use it on my Aikido? I’m too lazy to modify the socket, I decide to create a DIY Socket Converter, from B4 to Octal.

Most European tubes use this Socket. But in this project, I will specify the usage for RGN Rectifier tubes. Most of my RGN will use 4 Volt heater, while the standard Octal will use 5 Volt. What should I do? Piece of cake, just put 2 Resistors in both heaters line. Considering the RGN will consume around 1 A current, then 0.5R will do perfectly to drop from 5 Volt to around 4 Volt (I prefer to use 0.33R each to drop to 4.3 Volt, in case my main line drop a little bit at night).

Below is the necessary parts

An empty Octal socket, B4/B5 Socket, and two 0.33R resistors.

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Tags: Aikido, B4 Socket, DIY Audio, Octal Socket, RGN
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Posted on Saturday, 4th July 2009 by Jimmy Auw

Still remember the extreme capacitors battle? Well, we need to break-in those capacitors first for a fair judgement. So here it is. I don’t have much time to break-in those capacitors. Around 2-3 hours/night for next 2-3 weeks. I think this should be fine

All those capacitors stacked together:

• Duelund CAST 1uF/630V
• VCap 0.47uF/600V
• Jensen Copper Foil 0.47uF/630V
• Jensen Copper Foil Paper Tube 0.47uF/630V
• Mundorf Silver/Gold/Oil 0.47uF/1200V
• Mundorf Silver/Gold/Oil 1uF/1200V

All soldered together with WBT Silver Solder, connected to my Aikido via Silver Teflon interconnect. I use white cable heat shrink to cover all the leads (and for safety reason). This leads carry half of B+ or around 130VDC. Enough to shock you if touched.

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Tags: Aikido, Break-In, Duelund, jensen, mundorf, VCap
Posted in Collectible Stuff, DIY Audio | Comments (14)

Posted on Sunday, 28th June 2009 by Jimmy Auw

Just returned from a tired yet “deadly poisonous” DIY Gathering. We held an extra session with RGN 1054 Mesh Plate Rectifier and Duelund Capacitor installed on Aikido Pre-Amplifier (6N1P and 6N6P tubes). Before, the Aikido used Obbligato Capacitor bypassed with K72 Russian Teflon and 5U4G-B Sovtek Rectifier.

The result of this “simple” modification? A deadly Aikido Pre-Amplifier, even dare to compare with DHT Pre-Amplifier. Sweet, liquid, transparent, tight bass, and excellent speed. If before you have to choose between speed/dynamic (Aikido) and sweet vocal (most DHT), now you can get both on this!!!

Absolutely amazing. The test system supported with Audio Aero Capitole CD Player and 17W Class A MOSFET DIY Amplifier.

Tags: Aikido, Duelund, RGN Rectifier
Posted in Collectible Stuff, DIY Audio | Comments (3)

Posted on Tuesday, 31st March 2009 by Jimmy Auw

It was a nice session at DWA’s house located at Bintaro. We held a long session, from morning to night, from amplifier, preamp, DAC, to speaker. The event was started with a lunch ;)

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Tags: Aikido, Audio, Blind Test, clio, gainclone, solid state, speaker
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Posted on Monday, 29th December 2008 by Jimmy Auw

From my previous Aikido project, I’m still thinking of improvement of my B+ PSU. Well, I still hear a small hum. There are several possibilities to be tried, but I’m thinking of improving my B+ PSU first. If it fails, then I will think another way

From the LC-LC filter used before, I’m moving into a more filtering. Well, I’m talking about another stage of LC, creating LC-LC-LC filter. Previously, I used two Samhwa 220uF/500VDC capacitors. It’s a nice price/performance capacitor - I have to admit that. But, I need to change into a higher level (to see how much the improvement).

First I remove two Samhwa capacitors. It was a tiring job to remove those two capacitors (phewww). Then, I change the first capacitor with Korean “Motor Run” Oil Capacitor (60uF/400VAC), second capacitor with Mundorf M-Lytic 560uF/400VDC, then finally with another Korean “Motor Run” Oil Capacitor (40uF/400VAC).

Well, don’t ask me why I use this Korean “Motor Run” Oil Capacitor. It’s simply because I have no budget. If you have enough bucks in your pocket, go with ASC Oil Capacitor then

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Tags: Aikido, Capacitor, HV, power supply, preamp, PSU, tube
Posted in DIY Audio, Personal | Comments (2)

Posted on Monday, 8th December 2008 by Jimmy Auw

Finally, I put my Aikido Pre Amp on the chassis. Well, was a tough job since normally I didn’t do such thing (e.g. putting my DIY work on “little bit” neat chassis).

I separated inside the chassis into 3 chambers. The first one was for the main transformer, the second was for the power supply unit, and the last one was for the Pre Amp parts itself. I used 5 mm MDF wood covered with thick aluminum foil. The foil then grounded to minimize the interference.

Actually, I planned to put this Pre Amp to the Blind Test Session last week. But, the White Cathode Follower used in my Pre Amp seemed have some trouble when connected to higher impedance load (e.g. the input volume control on amplifier). I need to check it to find and confirm the problem later.

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Tags: Aikido, Audio, chassis, DIY-Audio, pre amp, tube
Posted in DIY Audio, Personal | Comments (8)