AMB Mini3 Portable Amp Detailed Review

[NwAvGuy]

I gave the AMB Mini3 (a DIY portable amp that's also available assembled) the full bench test treatment and it did respectably well in a few areas, but failed to meet many of its published specs--some by a wide margin. It's not very suitable for low impedance loads where it has relatively high distortion at most any output level.

A lot of its problems can be traced to using a virtual ground ("3 channel active ground" in AMB lingo). Such grounds work around having only a single battery in a portable amp, but in this case, it comes with significant side effects. I ended up writing a second article just about virtual grounds and 3 channel designs.

AMB Mini3 Review & Measurements

3 Channel Headphone Amps & Virtual Grounds

Questions and comments, as always, are welcome!

[The Larch]

Could you stop "water marking" all you photos?

[NwAvGuy]

Originally Posted by The Larch

Could you stop "water marking" all you photos?

So people can steal them? Sorry if it's annoying but entire articles on my blog are being ripped off and "repackaged" onto those spamfest websites that work the google algorithms to place high in search results. Without the photos watermarked, it's easy for them to strip out where the article even came from.

Here's an example of my review on a site apparently selling "MAX GXL":

http://www.whatisthemax.com/2011/04/...pro-80-review/

[Satellite_6]

Originally Posted by NwAvGuy

So people can steal them? Sorry if it's annoying but entire articles on my blog are being ripped off and "repackaged" onto those spamfest websites that work the google algorithms to place high in search results. Without the photos watermarked, it's easy for them to strip out where the article even came from.

Here's an example of my review on a site apparently selling "MAX GXL":

http://www.whatisthemax.com/2011/04/...pro-80-review/

Woah, that's pretty F'd up. :-/

[dfkt]

Scumbags steal the articles anyways, no matter if watermarking or not. The only thing that's relevant to them is that their ads get hits. Our ABI front page articles get stolen all the time, but there's nothing one can do about it. The guys behind these rehashing blogs are in India, Pakistan, and so on - and Blogger or Blogspot don't care in the least about protection of intellectual property.

[NwAvGuy]

Yeah, it's not good. But, at the least, the watermarks help identify the original source and probably discourage at least some theft.

[Adub]

I didn't really think about it as this is the 2nd time i saw this thread and the first time it was only the op. I didn't click on the blog initially because of the annoying watermark on the photo, and it was completely subconscious.

[hazza_t10]

Back to the actual article ... :P

I'm really glad to see a review of this amp, I've often been intrigued by how it would perform. I certainly agree with your conclusions about the 'three-channel' topology. Overall, a review that should certainly be read by anyone looking into a headphone amp IMO. As an engineer I also really appreciate the section with the extra technical bits

I saw some comments about the Fiio E5 design in there, that's something I would definitely be interested in. I find the E5 a very impressive bit of kit for its size, but I find it suffers very badly from mobile phone interference, which can be very off-putting.

Again, great stuff, and hope to see more where this came from!

[NwAvGuy]

Thanks for the kind words Hazza_t10. The cell phone problem might be solved by getting some clamp on (or loop through) ferrite chokes of the right size and placing one on the headphone cable near the plug and the other near the input plug for the E5.

The Mini3 is likely even more prone to cell phone problems because it has no RF filtering on the input at all and it's rather prone to interference problems in general due to the grounding scheme used.