eBay class A zero feedback amp

[batteryman]

Reads as perpetuating the 'Scottish ' stereotype: Frugal to foolishness .
Chi Fi is typically Crap.. and ebay variety is deservedly so.
Look elsewhere.
The DIY shoppe's Pass 'stuff' is not that much more $ and is a whole world of better quality

Scottish stereotype - I'll have you know I am 100% English!🙂

I have just rebuilt an A5 twice due to having had problems with mosfets getting too hot. It worked and sounded great on saturday; on sunday, it literally went up in smoke after 30mins. I will revisit it later as I never admit defeat. (I have a theead about it on the Pass forum)

I also checked my ML Aeons and they are 4R dropping to 1.32R@ 20Khz so I need to use a lower psu voltage with higher current so I planned to use the existing +-34v one with a different amp and chose that Ebay one from the choice of rip-offs, eg Krell KA50, etc. It's pot luck I know but £50 was as much as I wanted to risk.

 

[batteryman]

NO feedback = no stability

Tried these amps. All okay as regards quiescent current and output offset. But connect a screened cable to the phono sockets and rail to rail clipping occurs. Fortunately I did not connect my speakers, just my 'scope.

I think the Chinese have taken the phrase 'No feedback' literally and just omitted the usual feedback network so the gain is so high the whole thing has marginal stability.

Needless to say the seller won't provide a return address, won't pay the postage and won't supply a schematic so I can locate the issue. Their only comment was to say an Alps pot has to be connected to the input - without actually recommending a value.

Ebay will refund me in full in due course.