Marshall TSL602 bias settings


Can anyone tell me the correct bias settings for a Marshall TSL602? There is conflicting info out there.

Tthe TSL range have 3 pins under an inspection cover on the back. Some people say that the bias should be set to 40mv between the middle pin and the outer (total 80mv). Others say that it should be 80mv per side.

I’ve had the amp for 18 years and always have it set just short of 80mv, but I never seem to get much life out of my valves – probably half the 1,000 hours you’d expect. And the sound always seems to lack a bit of treble. Whenever I have it serviced, it always seems to come back set at around 80mv per side but it always seems to run a bit hot to me.

 Should I be lowering the bias?

asked 20 Mar 2019 at 11:52 AM

Phil Hitchman
Answers: 1


Hello Phil,

The bias on the TSL602 is 80mv the meter needs to be connected from the center pin to either side and set to 80mv. 

Kind Regards


Marshall Support


answered 22 Mar 2019 at 11:54 AM

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