Negative Feedback Question

a DIY, modified Mullard 5-20 monoblock design

Negative Feedback Question

Postby Toobgeek » Wed Dec 29, 2010 8:34 pm

This forum does not look too active and I hope someone can help me. after building a number of guitar amps, I've decided to try a stereo. After a lot of searching and going back and forth on which one, I stumbled upon this site and have decided that this is the one for me. I'm building from scratch. I've got my chassis, almost all of my parts and I have started drilling and soldering. However, the schematic show that the negative feedback come off the 8 ohm tap and then to the ground side of the input jack before continuing on to the circuit? It seems like this would just ground the feedback. Is this the way it should be done. It just doesn't make sense to me.

Thanks!
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Postby DeathRex » Wed Dec 29, 2010 9:04 pm

Well the signal goes from the 8 ohm tap to the ground tap because "12. Connect Rx53 in series with Cx21 from the ‘8 ohm tap’ to ground. This
provides a constant load for the amplifier even into inductive loads." I havn't done this before but I might try it.

The signal from the 8 ohm tap also goes to a parelleled 2Kohm resistor and 220pf capacitor then to the junction of a 1Kohm resistor and 100ohm resistor to the 12AX7.

The Eiclone is an improved version of the Eico HF-87/89. You can find the schematic for the Eico-89 and compare.
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Postby 20to20 » Sat Jan 01, 2011 10:41 pm

However, the schematic show that the negative feedback come off the 8 ohm tap and then to the ground side of the input jack before continuing on to the circuit? It seems like this would just ground the feedback. Is this the way it should be done. It just doesn't make sense to me.


I think it's just a bit of drawing imprecision. There is no dot to signify a connection.
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