Posted on Monday, 19th September 2011 by Auw Jimmy

Last week, we held a simple DIY Blind Test session. The contenders were all Class A amplifier (we can see F5, J2, Aleph, TUMOS, and some others…)

This was a hot session. Not just because the contenders were very good and serious, but the Class A itself means high current (=hot) and big heatsink (=heavy). So? You can imagine the rest

Below is the preparation of the session. The speaker was DIY 3-way with Vifa driver (XT25, P17, and PL26). The CD Player was CEC, while the Preamp was Aikido. Enjoy some photos below!

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Tags: Aleph, Amplifier, Blind Test, Class A, F5, J2, TUMOS
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Posted on Sunday, 18th September 2011 by Auw Jimmy

As  my Sowter Choke Input was acquisitioned by my friend. Then I have to consider some replacement. Actually my friend was interested with Hashimoto or similar, but as most of the Choke Input was designed for power amp, instead of preamp, so the specification and requirement (especially for minimum current demand) were different.

Luckily, as my preamp uses quite big current, then I can consider some Choke Input for power amp usage. One of them is the Hashimoto C-25-150CH. This choke is designed for Input application, rated at 25 H and 200 mA maximum current. DCR is claimed around 205 Ohm. Spec wise, it’s all very good to best. As material, Hashimoto is quite confident with its Orient High B core (forget Permalloy or Amorphous). Internally, this choke should be a C-Core type, with extra electrostatic shield. Oh, Hashimoto also put extra work to make this choke as a magnetic shield type. I think they do understand that Choke Input could radiate enough flux and/or electromagnetic things. Definitely, a magnetic shield design will be a nice addition. Build quality of this choke is also quite superb. With around 2.4 Kg weight, this is a heavy weight championship (remember, this is only a choke!)

The second one is a Tamura A-4004. Although it’s rated only 10 H and 200 mA maximum (or 2.5 H at 400 mA), this choke only around 10% lighter than Hashimoto Choke Input above. Physically size, this Tamura also a little bit smaller than the Hashimoto. Before, I was considering A-4006 (Amorphous) also. But due to some other consideration (as my Aikido Preamp already has Duelund CAST Ag Silver Capacitor inside), then I think non-Amorphous core will give a nice combination with it. Right or wrong? We shall prove it later…

Tags: Choke, Choke Input, Hashimoto, power supply, Tamura
Posted in Collectible Stuff, DIY Audio | Comments (3)

Posted on Friday, 16th September 2011 by Auw Jimmy

“USB On-The-Go” is not really a new thing actually. But since I have ‘exiled’ myself from the glamorous gadget world, probably I have missed this one. So, I just acquire a Nokia E7, featured with USB On-The-Go. Basically, you can plug a standard device like keyboard, mouse, or flash drive on it (and get a flexible control over your supported device). But I would like to try a different approach. How if I plug standard USB Audio Device (USB sound card)?

I read somewhere that the maximum power supply current supported is 200 mA. Well, probably some USB sound card could take more. But, no risk, no gain, right? I check several of my USB sound card collection and start playing around. Btw, I also plug my Samsung MP3 Player. The idea is to copy some music file from it. But eventually it starts to charge the device itself (damned, charging from battery to battery?). My Nokia E7 “screams” by showing a warning message that the connected device is consuming a lot of power (or similar warning – sorry, forget the detail).

I plug my MAYA EX5 USB sound card. Nokia E7 recognizes the device, but it says ‘limited function’. I think because MAYA EX5 uses non-standard USB audio device (it’s multi channel which is not common in USB audio peripherals). Since I think it needs special driver, then the Nokia E7 couldn’t redirect the sound into this sound card. So, we remove this from our list.

Then I find out a standard USB sound card, the ASUS Xonar U1 USB. This sound card is quite nice, with adequate headphone output quality. Nokia E7 recognizes this device with no problem and suddenly the music is redirected into the ASUS Xonar U1. I plug my headphone then start to enjoy the music.

FYI, the ASUS Xonar U1 used on this and shown on the photo below has been modded completely, especially on the capacitor side with Black Gate and Elna Cerafine. Click the link to find out the modification detail. The sound has improved in quite significant margin.

Below is the Nokia E7 connected to the heavily modded ASUS Xonar U1 via “USB On-The-Go” feature.

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Tags: DAC, E7, MP3, Nokia, sound card, usb, USB On-The-Go, WAV
Posted in DIY Audio, IT/Gadget | Comments (7)