What is an 'NFR' and 'NFL' lead?

[fallbalance]

Hey everyone,

First post here.

I'm modifying a Yamaha M80 amplifier by removing the relay board and running the channel leads direct to one set of binding posts.

In 2 sets of a bundle of three wires, there are a left and right lead, 2 negatives, and an 'NFL' and 'NFR' lead.

I was told that these may stand for 'Neutral Front Right/Left'. What exactly do they do?

Sorry if this is a redundant question, but I couldn't seem to find the answer through searches.

Thanks.

[burbeck]

hi
could be Negative Feedback Left and Negative Feedback Right ? best to get a diagram to check

[fallbalance]

Would a diagram be different from the service manual?

In the service manual, the wires are labeled "E, R, NFR" for the right channel and "E, L, NFL" for the left channel.

[burbeck]

the service manual would have the information

[fallbalance]

It's strange, there's no mention of it. I've looked through multiple times and tried to trace the leads as well.

I just looked up your suggestion of 'negative feedback left / right'. The article I stumbled across described that in amplifiers specifically, this is used to stabilize the output voltage of a circuit by connecting the negative output with the negative input. I don't quite understand it fully... bbuuuut it sounds like this is probably what these wires are, right?

I mean, they were running to a circuit board (the speaker relay board) which seems like a perfect fit for the description I read of a negative feedback circuit.

So, having removed this relay board, I should be able to cap off this negative feedback wire and just run my positive and negative signals directly to my binding posts, right?

Thanks for the help.

[DigitalJunkie]

Assuming they are indeed for negative Feedback -No.If you leave them disconnected you will be running open-loop,without any negative feedback. They should be connected to the speaker output (+) leads/terminals.

[fallbalance]

Hey,

Wow, I'm glad you mentioned that.

Do you think that they most likely are indeed negative feedback leads? For some reason the M80 service manual mentions nothing about what this abbreviation stands for.

Thanks-

[fallbalance]

I don't get why I would connect them to the positive speaker terminal and not the negative...? I only say this because of the title 'negative feedback loop'.

[Jan Dupont]

The LNF and RNF are the FB connections
You can easily trace them on page 9 in the SM
http://www.audio-circuit.dk/Schemati...M80-pwr-sm.pdf

[Enzo]

Feedback is positive or negative depending upon its phase relationship to the circuit, not whether it is the positive or negative terminal of the speaker.