DC-300A Pops / Clicks

[mynamegerg]

Hello All!

I recently acquired a DC-300a primarily to operate my 15" subs (potentional drive the whole 3way system) I have being built for a custom hi-fi / speaker system at home. While everything has been fine and dandy I've noticed that on both output channels of this DC-300a there is a small popping / clicking noise that emits when there's audio being played through this amplifier. Currently operating this amp through standard bookshelf speakers but I'd like to get this situation resolved before I go any farther with this project.

As far as I can tell the issue is consistent across both channels, which does not have a mono bridge switch leaving them seemingly entirely separate. I've tested two different speakers (both 8ohm) and the problem still is consistent. I understand with these older amplifiers I am to expected degradation in the caps and transistors, my question is has anyone seen this issue or diagnosed it before? Looking for guidance on where to start. Thanks

 

[JohnRoberts]

Hello All!

I recently acquired a DC-300a primarily to operate my 15" subs (potentional drive the whole 3way system) I have being built for a custom hi-fi / speaker system at home. While everything has been fine and dandy I've noticed that on both output channels of this DC-300a there is a small popping / clicking noise that emits when there's audio being played through this amplifier. Currently operating this amp through standard bookshelf speakers but I'd like to get this situation resolved before I go any farther with this project.

is it silent when the music is quiet? Do the pops and clicks change with the level of the music.

As far as I can tell the issue is consistent across both channels, which does not have a mono bridge switch leaving them seemingly entirely separate. I've tested two different speakers (both 8ohm) and the problem still is consistent. I understand with these older amplifiers I am to expected degradation in the caps and transistors, my question is has anyone seen this issue or diagnosed it before? Looking for guidance on where to start. Thanks

capacitors in amplifiers that old are suspicious, transistors are generally good, until they are not.

JR

 

[mynamegerg]

Yes the unit is silent when the music is quiet. I believe this is more of a capacitance issue more than anything. I just tested the unit again with a different input chain and had some oddities present itself. The first one I noticed is that when the unit is powered down the speaker will resonate an audible tone for roughly 15-20secs until it goes silent.

When I tested the second channel it was completely distorted now and could not drive the signal properly. In addition to that issue when I powered the unit off it continued to play the music at a much lower level until it faded out which took well over a minute. This is not an issue with the first channel or at least it has not presented itself just yet.

 

[JohnRoberts]

could be bad switch contacts, bad solder connections, or bad capacitors.

JR