Jimmy’s Junkyard

Custom Made Power Transformer for My Pre-Amp

Posted on Sunday, 22nd November 2009 by Auw Jimmy

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.

trafo_setiawan_2

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Tags: Aikido, preamp, transformer
Posted in DIY Audio | Comments (6)

Pre-Amp #26 Parafeed – Tweaked with Jensen Copper Foil Paper Tube

Posted on Sunday, 22nd November 2009 by Auw Jimmy

I visited my friend’s home few days ago. We planned to tweak his #26 Pre-Amp (with Parafeed design).

His Pre-Amp was a high quality pre-amp, in terms of parts and design. As you can see below, the high voltage section has Black Gate SKZ capacitor.

He just finished tweaking the high voltage section by adding 3 huge Russian Teflon capacitors (FT-3) and got significant improvement on the sound staging. He was poisoned by the VCap Power Supply trick as I did on my pre-amp, so he tried the cheap Teflon solution first, the Russian FT-3 before going down deeper with VCap

26-jensen

At first, his #26 used Jensen Capacitor Aluminum Foil. The overall sound is live, fast rhythm, and dynamic. A little bit less sexy on the vocal side for my taste and the top end detail was a little bit “flat”. Then we changed to Jensen Copper Foil Paper Tube. How did it sound? Keep reading.

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Tags: 26, jensen, preamp, preamplifier
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VCap TFTF on Power Supply Test

Posted on Sunday, 6th September 2009 by Auw Jimmy

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?

vcap

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Tags: Aikido, power supply, preamp, VCap
Posted in DIY Audio | Comments (13)

Another Aikido Pre-Amp Mods

Posted on Sunday, 23rd August 2009 by Auw Jimmy

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).

psu-divider

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
Posted in DIY Audio | Comments (4)

Aikido High Voltage/B+ PSU Mod

Posted on Monday, 29th December 2008 by Auw Jimmy

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