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Tuesday, July 15, 2008
AMB Labs Mini3 Review
[ZOMBiE CyGiG] ranted at 12:08 AM --- Post#3460544275259206524

Introduction

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Among the sea of portable amp, lies this low profile gem - the AMB Mini3. AMB Labs design audio productions, ranging from amps to buffers to power supply. Unlike conventional brand, they dun manufacture and sell the product. They sell only loose components, meaning u got to assemble the parts yourself.

A usual DIY kit cost maybe $110 to $130, from hohodiy or amb audio shop or local supplier. I got mine at a much lowered cost for special reasons.

A little search in head fi yields this link. Numerous ppl claim that the mini3 is better than the state-of-art Hornet that cost nearly $600! WOW! Too bad i dun have a Hornet to test it out.

Specification and Technical Highlights

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Opamps: AD8397ARDZ (left and right) and OPA690ID (ground)

- In addition to the left and right channels, the "ground" wire of the headphone is actively driven by a third channel. The ground channel amplifier sources or sinks the return current from the transducers. This results in lower output impedance, greater linearity and reduced stereo crosstalk.

- Precised Virtual Ground. The TLE2426 ensures that as the battery drains down, the power supply rails to the opamps remain evenly-split.

- Fully direct-coupled. There are no signal-degrading coupling capacitors at the input, output or negative feedback loop.
This is a true DC amplifier. Care should be taken to ensure that the input source does not have DC offset at its output.

- Built in battery charging circuit, NO auto cut off though.

- Mine is the high performance, gain 5 set.

The DIY Work

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Definitely not easy for a noob like me, it took me 2.5 hours to assemble the set. Luckily the resistors are already labeled, so it saves me time looking for the correct value. The PCB itself is quite self explanatory, with reference to the AMB webby, you should get all the info that you will need.

The hardest part is obviously the surface mounted opamps. Another harder part is to sand away part of the casing to allow the ground strip of the PCB to make contact. Aligning the LED to fit the hole requires a few tries as well. The voltage regulator's bolt and nut is not included in my kit.

I found that the default jacks aint very good, they have problems with the neutrik's. When i insert the plug i can feel the contacts awkwardly placed in the way, and feels a bit flimsy. I went to Bell's to get another pair of jacks to replace them, they come with exposed screw on heads. A little precisely cut heat shrink tube solve the problem with ease. Much firmer and tighter now.

Sound Signature

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D2 > SilverMAX Quad Braid > Mini3 > Triple Fi/ ESW9

One word: CLEAN. A rather analytical cold sounding. Well balanced sound, with lots of accuracy and transparency. May be a bit too neutral for some.

The highs do not have harsh, crispy and a bit bright.

The vocals is interesting, sounds like a typical AD8397, its sunken into the music and does not stands out brightly or warmly (neutral). Dun get me wrong, its still in its tip top form of clarity and accuracy.

Bass, LOTS, esp with the quad braid SilverMAX IC. Nice controlled bass that wun make u fatigue.

It really put my ESW9 to life, never knew it can sound so nice!

Overall the mini3 sounds rather unbiased and very analytical, to a point of what i call "coldness". Untainted sound and transparency is its ultimate weapon. No wonder it can put up to a good fight with the Hornet.

Let's Compare!

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Poor, me, I only have my Petite to compare. The most recently heard amp is the Magnum. Both the Go Vibes portray one similarity - muddy bass with lots of dynamics. Magnum wins in clarity and accuracy in the highs and mids over the Petite. This is opposite of what mini3 offers.

For me i like coloured dynamic sound, it will take some time to adjust to the analytical Mini3. But the clarity and cleanliness made me abandon my Petite. It would be harder to choose between Magnum and Mini3, though the mid bass of Magnum is a bit too much, it does put lots of punch into the music. Another down side is the price.

Side Track: Go Vibe Petite Sexposed!
After soldering the mini3, it got me interested to strip the Petite. Here are the pics of the PCB.

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The opamps are spray painted. I see lots of unoccupied spaces on the PCB, why are they missing? I even see a space allocated for another opamp.

It may be that the circuit was simplified from the original design to cut cost or cut power usage or cut space or just to create a lower end product to target another user group.

This original design may be one of the previous Go Vibe products or a newer one (Magnum?). A common PCB was made to save cost and trouble.

Another possible answer is that those missing components are meant for the DAC version.

Conclusion
For such a price, mini3 is DEFINITELY worth it. Looking for a high end portable amp and cannot afford the RSA's? Try your luck with Mini3. But first u got to learn soldering :)

Actually there are some ready made mini3 in the market for u to purchase. Also i can sense the urge to start modding the components already...hehehee..

All photographic materials in this review are by the authour, me, ZOMBiE CYGiG himself. No unauthorized usage or linking.

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