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PostPosted: 05 May 2020, 19:40 
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Are the transformer secondaries out of phase on one of the amps?

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PostPosted: 05 May 2020, 19:47 
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Was just listening to the 6EM7 Vertical amp playing a wide ranging mix from my computer music library and the Eagles' "One of These Nights" started to play. This track has some great bass lines at the front end and this amp, with it's great bass extension, really did them justice.

Even now it sometimes surprises me how great a good SET sounds. :sing:

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PostPosted: 06 May 2020, 03:12 
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I would replace the 100ohms with high wattage 2 watt ones.
I suspect this to be the prolbem


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PostPosted: 06 May 2020, 04:35 
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ILoveHiFi wrote:
I would replace the 100ohms with high wattage 2 watt ones.
I suspect this to be the prolbem


I'm a little concerned with this approach. Isn't that a bit like putting a bigger fuse in a piece of equipment because you don't know why the correct size fuse keeps blowing?


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PostPosted: 06 May 2020, 04:44 
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Suncalc wrote:
Are the transformer secondaries out of phase on one of the amps?


Just rewired the secondaries on the problem amp and will run it for a few hours to see if the problem is solved.
It does make sense as it is the only possible difference between the two amps. With a 50/50 chance, I could have got lucky, but it seems I didn't.


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PostPosted: 06 May 2020, 05:15 
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The 100R resistors consumes allot of power, you can come back to me and tell me your estimation of the power consumption after visiting the ohms law formula wheel to do some calculations.


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PostPosted: 06 May 2020, 06:29 
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I reckon just under 200mW (6.3v squared over 200 ohms), but my maths are always a bit dicey. If they're wrong could you correct me?
As one monoblock works fine with 0.5W resistors it seems logical to assume there is incorrect wiring in the second monoblock.


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PostPosted: 06 May 2020, 08:24 
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john55 wrote:
I reckon just under 200mW (6.3v squared over 200 ohms), but my maths are always a bit dicey. If they're wrong could you correct me?
As one monoblock works fine with 0.5W resistors it seems logical to assume there is incorrect wiring in the second monoblock.


True!

Are you using elevated DC bias for the heaters? There might be an error and some current flowing through the resistors?


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PostPosted: 06 May 2020, 11:57 
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I would double check that you are getting 6.3 volts across you filaments and a balanced 3.15 volts to your center tap.


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PostPosted: 06 May 2020, 12:57 
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mike567 wrote:
I would double check that you are getting 6.3 volts across you filaments and a balanced 3.15 volts to your center tap.


Yep they're both spot on.


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