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.
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.
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.
In the service manual, the wires are labeled "E, R, NFR" for the right channel and "E, L, NFL" for the left channel.
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.
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.
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.
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-
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-
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'.
The LNF and RNF are the FB connections 😉
You can easily trace them on page 9 in the SM
http://www.audio-circuit.dk/Schematics/Yamaha-M80-pwr-sm.pdf
You can easily trace them on page 9 in the SM
http://www.audio-circuit.dk/Schematics/Yamaha-M80-pwr-sm.pdf
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.
Thanks for the responses.
Sorry, this is a bit new to me - what does FB stand for? I traced the leads on the main board... it looks like they run to part# C104 and C103... which in the index is labeled as a 'mylar cap'. I couldn't trace it beyond that.
So I should just run this wire to my positive speaker lead?
Thanks-
Sorry, this is a bit new to me - what does FB stand for? I traced the leads on the main board... it looks like they run to part# C104 and C103... which in the index is labeled as a 'mylar cap'. I couldn't trace it beyond that.
So I should just run this wire to my positive speaker lead?
Thanks-
I know this is a DIY board, but why are you bypassing the relay? You may get some nasty turn on/off noises without it (maybe not), and you will probably loose whatever protection is offered by the circuit driving it, yet the circuitry will still be there - just no relay, correct?
If there is something wrong with the relay, replacing it may be a better option. If the relay is interrupting your music, the problem may not be the relay - it might be protecting your speakers from massive DC.
If there is something wrong with the relay, replacing it may be a better option. If the relay is interrupting your music, the problem may not be the relay - it might be protecting your speakers from massive DC.
I know it seems crazy, but this is actually a somewhat common modification for these amps. Apparently they made a switching board to save on costs - they are known to crack commonly as well as add a small amount of noise to the signal. Also, the stock binding posts are bare-wire only and aren't of the highest quality. These parts of the M80 aren't up to specs with the rest of the amp, which is excellent.
The Yamaha M series were designed to have binding posts for 3 sets of speakers. I'm eliminating this and installing quality posts for just one set. I have an M40 that was modded by someone else and they took the entire board out as well, hard wiring the speaker leads to the binding posts. It works and sounds excellent.
It looks like, judging from the schematics, that the M80's wiring is slightly different from the M40, but the same principle applies - sooooo I'm hoping that removing the relay board will have no ill effect.
The Yamaha M series were designed to have binding posts for 3 sets of speakers. I'm eliminating this and installing quality posts for just one set. I have an M40 that was modded by someone else and they took the entire board out as well, hard wiring the speaker leads to the binding posts. It works and sounds excellent.
It looks like, judging from the schematics, that the M80's wiring is slightly different from the M40, but the same principle applies - sooooo I'm hoping that removing the relay board will have no ill effect.
That's cool, sometimes people just want to bypass things or remove/improve parts without any idea what effect it will have or why they are there in the first place. If it is an accepted upgrade, go for it.
Yes, the NFL lead should be connected to the L+ post and the NFR lead should be connected to the R+ post. This assumes that the two channels grounds are the same and that it is not a balanced or bridged amp. I have seen other amps like this where the connections are made at the farthest possible point inside the amp but before any switches or relays. On amps with no relays I have seen them connected right to the back of the posts. Make sure the amp is not operated without those leads connected, it will quite possibly oscillate into self destruction if the connection is bad. That self destruction would likely take out your tweeters as well. I would test it with some sacrificial speakers before hooking up your beloved speakers.
Yes, the NFL lead should be connected to the L+ post and the NFR lead should be connected to the R+ post. This assumes that the two channels grounds are the same and that it is not a balanced or bridged amp. I have seen other amps like this where the connections are made at the farthest possible point inside the amp but before any switches or relays. On amps with no relays I have seen them connected right to the back of the posts. Make sure the amp is not operated without those leads connected, it will quite possibly oscillate into self destruction if the connection is bad. That self destruction would likely take out your tweeters as well. I would test it with some sacrificial speakers before hooking up your beloved speakers.
The difference is, that with the relay out of the circuit you have NO protection for your speakers. Blow up the amp, and wave goodbye to your woofers (keep a fire extinguisher handy too).
Thanks for the info CBRworm!
Echo - Really!? Are you sure it doesn't just act as a switching board for the three speaker sets? I have an M40 with the relay board removed, and it still kicks into protection mode on startup, whenever there is a power drop, when speaker wire is crossed, etc...
Originally, speaker sets A and B were run in parallel, and set C was run in series, so the wiring was easier for Yamaha to do with a circuit board I think.
How can I tell if there is a protection circuit on the relay board? I'm looking at it now and it all just looks like speaker switching circuits... but I am pretty new to this, so I could be missing something.
Echo - Really!? Are you sure it doesn't just act as a switching board for the three speaker sets? I have an M40 with the relay board removed, and it still kicks into protection mode on startup, whenever there is a power drop, when speaker wire is crossed, etc...
Originally, speaker sets A and B were run in parallel, and set C was run in series, so the wiring was easier for Yamaha to do with a circuit board I think.
How can I tell if there is a protection circuit on the relay board? I'm looking at it now and it all just looks like speaker switching circuits... but I am pretty new to this, so I could be missing something.
Hey again everyone,
Another question here. I just spoke with a relative who is circuit savvy. He said the experience he has seen with negative feedback loops has been in OPamps. He said that the signal being fed back to the negative feedback circuit was usually attenuated to something around a tenth (1/10) of the actual amplified signal being fed to the speakers.
This made me nervous, of course. Yet, I don't see anything in the schematics of the relay board that would attenuate the signal being fed to the feedback wires...
Could it be that the attenuation happens on the main board? Or could it be that the feedback signal is built to be equal to the actual output signal? What do you guys think?
Another question here. I just spoke with a relative who is circuit savvy. He said the experience he has seen with negative feedback loops has been in OPamps. He said that the signal being fed back to the negative feedback circuit was usually attenuated to something around a tenth (1/10) of the actual amplified signal being fed to the speakers.
This made me nervous, of course. Yet, I don't see anything in the schematics of the relay board that would attenuate the signal being fed to the feedback wires...
Could it be that the attenuation happens on the main board? Or could it be that the feedback signal is built to be equal to the actual output signal? What do you guys think?
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