Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: jrc111 on June 23, 2021, 06:41:28 pm
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I have a Hot Rod Deville 212 overdue for a recap, and I’d like to put a multi-tap Output XFMR in it while it’s down, to take advantage of some extension cabs I have. In the circuit below, the gray wire is the “feedback” lead, tapped into the 4 ohm XFMR output. Any problem leaving that as is, and putting multiple jacks: 2, 4, 8, and 16 ohms, and power off, just plug in what I’m using, and leave the feedback wire where it is?
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leave the feedback wire where it is
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The feedback wire should always connect to the 4Ω output, regardless of which impedance jack you connect speakers.
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Thanks! I’m going to use the same scheme for a Hoffman Princeton Reverb I’m collecting the parts for, and thought I’d try this first.
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just adding this so you know the why: https://www.aikenamps.com/index.php/designing-for-global-negative-feedback
long story short, you could attach it to a different tap, but then would need to change the nfb values to achieve the same sound/response
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..., you could attach it to a different tap, but then would need to change the nfb values ....
And since the several taps are coupled to give 99.8% the same signal (at different voltage), only rabid hi-fi fans could care. Yes, keep the same NFB tap as designed even it you put speaker on another tap.
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Awesome stuff. Thx!