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T2 First Use - Very Low Volume on both channels

Hi there, I've just powered up my T2 for the first time and the volume is very low on both channels (only just audible when turned all the way up). Voltage: 26.5V DC (lead acid batteries) Speakers: 8 Ohm (measured at 6.5 ohm at amplifier output) Source: Headphone level output (iPhone) - L/R channels properly isolated - Both LED's light up (one when powered on and the next shortly after as the relays are activated) Any ideas? Thanks

Check the input cabling, as this would be the most common cause for problems.

Also, the iPhone output level is not very strong, so you will not get full output from the T2 with an iPhone. But make sure the iPhone level is set to max (including any setting in the program you use). If possible try another source with higher output.

That makes sense - I used an XLR socket for the input on the amplifier housing and must have connected the T2 to chassis ground instead of the wired ground from the source. I'll check later and report back. Many thanks for the quick response!
That seems to have done the trick - thanks! The level still isn't a loud as expected so I'm going to replace R3 and R5 with 40k resistors. They look like 0603 - is there any reason why I can't replace them with 0402 as I only have these to hand? Thanks.

We use 0805 actually, but yes you can use 0402. 

I've just had another look at this. The level is still very low. Note: I've haven't swapped out R3 and R5 yet so the board is currently still unmodified. The grounding issue appears to be on board itself - the track between connector J1 pin 2 (SGND) and the through-hole via is open circuit. I can't tell whether its a production fault or if the track burnt out. Am I okay to wire between R6/R7 and the connector to reinstate the SGND connection?
I think the track may have burnt out (can feel a slight indentation with my multimeter probe).

Hi Toby, the topside of the board is filled with SGND plane, so no need to wire to R6 or R7. You can wire to potmeter pin1 or 4.


I've connected between the connector SGND to SGND on the potentiometer and it is up and running. Thanks.
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