mini Aleph hum

[Gregje]

Hi there,

Recently I have moved speaker gnd and input gnd to the star gnd point.
The speaker ground seems to make no difference (as I kind of expected - ie no difference if the speaker negative terminal goes to the gnd on the pcb or to the star ground). Moving the input gnd to the star point improved the hum issue considerably. In fact the amp is dead quiet (connected to the system). The hum gets worse when the preamp is powered. I will look there now.

 

[Gregje]

The preamp hum has been resolved as well. I increased the regulation in my linear psu. 1V more drop and an extra capacitor and I seem to be sorted ;-)

 

[skiroe]

I am the owner of the Bengali amp and wanted to input here and thank Bengali for all the time and energy he put into the hum issue. Initially, the amp indeed had quite a bit of hum which could be heard at times even with music on depending on what type of music was played. It could be heard from even farther away than 5 ft on a quiet evening with no ambient noise. The initial speakers that were used were Decware 944 @4ohm although I was told that isn't really a 94db speaker if its 4 ohms. Currently the amp is driving Hoyt Bedford 97db@8ohm full range monitors.. These were in house "budget" line from Omega Speakers. When I first got the amp back from Bengali I did notice an improvement with reduced hum... What is interesting is that the hum has further reduced over time and that is what prompted me to search out this thread and report. I had the amp hooked up to a hum buster for awhile (not initially!) which will potentially only work for hum at speaker and not mechanical hum so I thought this application might help. So the hum buster did not seem to make any difference. I went back to plugging directly to a power strip .. I have noticed that speaker hum is lower than its ever been -- ear has to be directly inches from the driver so that is quite fine for me. Certainly dont hear anything with volume @ O or with music on as could happen in the past. Im not equating this lower hum with deleting the hum buster from the chain-- I dont know for sure. Haven't really been checking for hum for awhile until just recently. So, whatever Bengali did --it helped and the mysterious part is it has seemed to further improve with time and usage. Hope it stays that way!