Express 1.5K pin 5

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DaveWell
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Joined: Wed Feb 25, 2009 9:59 pm

Express 1.5K pin 5

Post by DaveWell »

Hi !

The 1.5K 2W on power tube Pin 5, is they have to be right on the socket or can be under the board ?

or ... Why not using 221.5k 2k resistor to join pin 5 and board ?

Thanks
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martin manning
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Re: Express 1.5K pin 5

Post by martin manning »

Grid stopper resistors are always best placed on the sockets. That is where they are most effective at preventing oscillations.
Bob S
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Re: Express 1.5K pin 5

Post by Bob S »

Sage advice from Martin. The Express circuit is on the edge of stability as is.
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Stevem
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Re: Express 1.5K pin 5

Post by Stevem »

Another concideration with any build or in making a production amp better is the lenght of the overall distance the signal travels from the plates of the PI section to the grids of the output tubes.
Sometimes anything over 2.5" is asking for a osscilation issue, or instability if the amp uses a feedback circuit.
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