Hi all, its been a while since i finished my 6 channel compact amp, with minidsp built in.
I started dozens of threads and got loads of help.
The system (which includes some lovely translam speakers/subs),Is working like a charm.
Amp uses a connex smps 800w psu, and two tpa3255 reference boards.
The signal ground is isolated from the chassis ground.
Today i was shifting the amp a bit on the shelf, while it was on. i touched both the aluminium chassis and the speaker negative terminal. I got a "tingle". I dont remember it ever happening before..
Is that normal? Assuming not, what can i look for/check?
Thanks all!
I started dozens of threads and got loads of help.
The system (which includes some lovely translam speakers/subs),Is working like a charm.
Amp uses a connex smps 800w psu, and two tpa3255 reference boards.
The signal ground is isolated from the chassis ground.
Today i was shifting the amp a bit on the shelf, while it was on. i touched both the aluminium chassis and the speaker negative terminal. I got a "tingle". I dont remember it ever happening before..
Is that normal? Assuming not, what can i look for/check?
Thanks all!
Although there are several modes possible for the TPA3255 I believe you have just discovered that yours is operating in bridged topology. That means BOTH (+) and (-) are actively driven. You touched an active point (the speaker connector) and a ground point (the chassis), and got a shock.
Next time try turning the amp OFF before touching the speaker terminals...
Next time try turning the amp OFF before touching the speaker terminals...
The danger with a shock is also dropping what you are carrying.
I find about 90VDC is when I start getting a shock.
Get a mild one when brdging +/-45VDC across output transistors.
800W speaker wires carry voltages above 35Vrms and are thus subject to different rules in the UK regulations for instance, counting as "hazardous live" for domestic equipment.
Commercial equipment in the UK regulations is allowed upto 120Vrms before being considered "hazardous live".
(According the the testing and safety section of Doug Self's book).
Basically you should be using SpeakONs or powering down before fiddling with speaker connections. In a domestic environment any speaker connection at these voltages must be child-proof, ie inaccessible to small fingers (the UK regulations dictate particular tests for this).
Commercial equipment in the UK regulations is allowed upto 120Vrms before being considered "hazardous live".
(According the the testing and safety section of Doug Self's book).
Basically you should be using SpeakONs or powering down before fiddling with speaker connections. In a domestic environment any speaker connection at these voltages must be child-proof, ie inaccessible to small fingers (the UK regulations dictate particular tests for this).