[MisterX]

Not exactly headphone related but they have some pretty nice looking kits:
http://www.ampslab.com/products.htm

The question that begs to be asked..... has anybody ordered from them before?

 

[peranders]

I haven't ordered anything but have been in contact with concering using a patented design from Analog Devices. This design is protected by the US patent 5097223 but Analog Devices gives permission to build this amp for personal use so I think it's OK for to do what he does. Besides, the patent is only for US.

http://www.ampslab.com/bi300_schematics.htm
http://www.analog.com/UploadedFiles/...17334AN211.pdf
Better quality here:
http://www.sjostromaudio.com/hifi_fi...etter_text.pdf

Despite this Alexander amp I think his stiff is pretty OK.

None of the designs (except for the Alexander amp) aren't exactly rocket science but I don't see any wrong to do good stuff which hs to be proven to work good in the long run.

This Ampslab gentleman has also the ability to communicate depsite the fact that he is asian. Some other asians have been prone to answer "yes" to everything no matter how wrong they are. Loosing the face is harder than have a mature discussion about things where the answer sometimes not is "yes".

 

[Dougigs]

(duplicate post see below)

 

[Dougigs]

I'd forgotten about the Alexander amp -- I was really taken with the design when I first saw it a couple years ago. The current-feedback approach works really well with op amps -- my favourite solid-state preamp is one I built using CF op amps inside a Jung loop.

Has this topology been used much in power amps by DIYers? I wonder if anyone has made up Eagle files for Alexander's PCB design... it seems like an ideal ready-to-build power amp circuit that would make a very high-end amp.

 

[peranders]

How things are built is a kind of fashion and not very many design really. Sonny Andersen http://mirand.dk did some work with current feedback at the same time I did but building powerful current feedback amps have it's challenges and also designing a good Alexander amp.

So... the Alexander amp is rather forgotten and/or not fashion.