Help with Spectrum ll

[flythair1]

Hello Community,

This question might belong in the Sunn section, but this area looks to have more traffic.
My Sunn Spectrum ll uses the 8 ohm tap on the OT (OT has 4, 8 & 16 taps) for the feed to the NFB circuit. The schematic I have from Schematic Heaven shows the 16 ohm tap being used for the NFB. The 16 ohm tap was unattached to anything when I got the amp.
I had this amp to a shop and pointed out the difference to the tech and when I got it back repaired, they had attached both the 16 & 8 ohm taps to the NFB circuit. This does not seem correct to me but I am a novice, especially with Sunn amps. I have not tried the amp yet and wanted to check with great knowledge-base here to see if it is safe to do so as is.
Thanks for your comments.

Scott

[Twist]

You may not notice the difference but I would go ahead and hook the feedback to the 16 ohm tap. You could disconnect the feedback completely and see if you like it. Just don't run the amp without a speaker load.

[Enzo]

Unless I don't know how they did it, connected both to the NFB would tend to short the two together wouldn't it? Pick one and use it. it is not like picking the "wrong" one will hurt anything.

[flythair1]

Thanks for your replys Twist & Enzo.

That's what I needed to hear Enzo, I hoped you would comment. I wish I could pick your brain for a few weeks.

The wiring with the 8 ohm tap connected to the NFB looked like it was factory, the 16 ohm tap was dead-ended on a terminal strip and the wire from the 8 ohm tap to the NFB matched other obviously original wiring.

Is it possible to hook the taps & NFB lead in conjunction with a switching jack so-as to detach the NFB from the circuit with the correct jack plugged into?

Anyhow, thanks again. I'll return the wiring to what it was as I know that works.

Scott

[Enzo]

The NFB is a voltage signal back to the circuitry. it does not have to be tapped off the same place the speaker taps off, it doesn't care where the speaker is. No need to switch it around with the load.

If you just have to though, then take the NFB from the output jack and use a selector switch for the impedance. Then whatever tap you select will get the speaker and the NFB line.