I am new to this forum and hoping to find some guidance on where to start on a project I have been planning to do. I have no technical knowledge around speakers and their design but have an engineering background and can work my way around some electronics. Was hoping here might be a good starting point.
I have a 70's intercom / radio built into the wall of my kitchen / dining area which I would like to modernize to play music at higher quality as now it has lots of static and generally low quality. Not looking for a super HiFi system, but I would like it to be good not like just some alexa/google home speaker quality. I would like to keep the aesthetic of the device and all exterior features of the unit, but gut out the internals as the inside looks like a circuits lab, project bread board. It would be a plus for the knobs to be functional to some capacity as well. The unit measures at about 17 x 9 inches, and play into an area about 15 x 15 ft wide. I have added some images for reference of the unit on the wall.
I have a 70's intercom / radio built into the wall of my kitchen / dining area which I would like to modernize to play music at higher quality as now it has lots of static and generally low quality. Not looking for a super HiFi system, but I would like it to be good not like just some alexa/google home speaker quality. I would like to keep the aesthetic of the device and all exterior features of the unit, but gut out the internals as the inside looks like a circuits lab, project bread board. It would be a plus for the knobs to be functional to some capacity as well. The unit measures at about 17 x 9 inches, and play into an area about 15 x 15 ft wide. I have added some images for reference of the unit on the wall.
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Cool project! 
I don't think that turning it into a smart speaker would too hard, but keeping the knob functions may not be easy.
Does this on use the speaker as the microphone?
I don't think that turning it into a smart speaker would too hard, but keeping the knob functions may not be easy.Does this on use the speaker as the microphone?
On some units like that I preferred to listen to AM because the built in ferrite loop antenna was more successful than the random FM antenna. Then there is the possible incidence of other wiring in the wall. So that's where I'd look first to clear up the static.
I'd think it would benefit from having separate speakers if that's possible. How about building a new amp to fit, use same knobs to control it and use the selector knob to chose between internet radio, streaming or source of your choice?
Looks like a model 2561 or 2562. These guys have service manual downloads for this stuff, along with lots of other helpful material.
While I am not sure what fidelity on these units could ever be (maybe like a large radio of the time), I am quite certain that some pot cleaning and maybe the odd new electrolytic would improve performance quite considerably. Try finding out which chassis you've got in there, with some luck it'll be the version with silicon transistors instead of the older all-germanium circuitry at least. Looks like they kept bringing out new versions well into the '70s.
While I am not sure what fidelity on these units could ever be (maybe like a large radio of the time), I am quite certain that some pot cleaning and maybe the odd new electrolytic would improve performance quite considerably. Try finding out which chassis you've got in there, with some luck it'll be the version with silicon transistors instead of the older all-germanium circuitry at least. Looks like they kept bringing out new versions well into the '70s.
Not quite sure to be honest, need to open it back up to see the internals and where the mic is placed. Havent looked at the insides in a while. This was the inspiration to my idea, Intercom Project - Album on Imgur, and some what similar unit to mine. Though I have no idea the quality of speaker used in that project and what can be done to improve upon it.
when you say separate speakers, do you mean like using multiple drivers within the unit?
Well no, I'm assuming that behind the plastic or bakelite grille there's a driver like many found old radios. Separate, good quality speakers, placed outside the unit (because of limited space) could help deliver better sound quality.
You might prefer to keep the unit operating independently of course.
> I'm assuming that behind the plastic ...grille there's a driver like many found old radios.
It "IS" a radio, slightly customized. NuTone faceplate of course. Input/output taps for remote speakers and sources, a "microphone preamp" so a remote speaker can be talked into. I would bet NuTone solicited bids from the major good radio builders (NuTone could have built the electronics but other factories would be better/cheaper by adapting existing products to NuTone's need).
"Driver" is a fancy name for a loudspeaker. That dim jerky video gives a glimpse. A 4", 5" or 6". I've handled many dozen of these things. That one looks a bit better than the battery Sanyo in my barn, a little less than the nice Sony in my garage-- not bottom-barrel but nothing special. Since the buyer never saw it, the magnet was not as large as usually seen on "raw" drivers.
It "IS" a radio, slightly customized. NuTone faceplate of course. Input/output taps for remote speakers and sources, a "microphone preamp" so a remote speaker can be talked into. I would bet NuTone solicited bids from the major good radio builders (NuTone could have built the electronics but other factories would be better/cheaper by adapting existing products to NuTone's need).
"Driver" is a fancy name for a loudspeaker. That dim jerky video gives a glimpse. A 4", 5" or 6". I've handled many dozen of these things. That one looks a bit better than the battery Sanyo in my barn, a little less than the nice Sony in my garage-- not bottom-barrel but nothing special. Since the buyer never saw it, the magnet was not as large as usually seen on "raw" drivers.
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My suggestion would be to have it serviced by a knowledgeable tech familiar with the Newtone systems.
I've had these in the repair shop before, and they can benefit from some service - they actually don't sound bad after that.
Also, a better speaker(s) helps. - compatable replacements of better quality can be installed.
But as far as "changing" the guts, it's best to leave well enough alone.
Otherwise, a chunk of drywall can fill the hole in the wall.
So I found out the unit uses a 6" X 9" 45 ohm shallow diaphragm speaker cone. Having a hard time finding drivers of the same size, I think i might just keep the original one for now and scrap the idea to keep the buttons functional.
I am deciding to get a used google home mini, and cut the output lines into the speaker of the Nutone (similar to this, https://www.instructables.com/id/Google-Home-Mod-Into-a-Vintage-Radio/, but for now I will use the original speaker. If that works well I may stop there, but if you have any suggestions for loudspeakers that could be a good replacement that would be helpful.
Thing is I have no value for the intercom system as a whole other units in the house have been removed by previous owners. I like the aesthetic of this unit, but would prefer something more functional.I am planning to cut the speaker as an output for a google home. I may keep the current internal components in tact for the ability to revert my modification. But not sure just yet.
6x9 is common in car radio rear decks. You can get very good "3-way" 6x9s. But all 4 Ohm. The 45 ohm eases using the speaker as a microphone. If all the other stations have been scrapped, no matter. However a "line transformer" 10 Watt 25V would come close to 45 Ohms.
But personally, I'd put Velcro on the faceplace and keep my whiskey in there.
But personally, I'd put Velcro on the faceplace and keep my whiskey in there.
If i were to swap to an 8 ohm full range driver, would I have any issues with the original wiring for the 45 ohm speaker? And in reverse, would a google home mini which has a 4 ohm speaker have a problem if wired to the 45 ohm speaker of the intercom?
I have been doing more research came with the an idea to retain the original device function. I am thinking using a 4PDT switch, wire the original radio/intercom and a google home mini to the 1 output speaker (maybe 2 speakers, but not sure if this will then also require an amplifier or some other things). In the image attached, thinking to just cut that line and add in the switch there and wire in the google output into the switch as well. There is a hole at the bottom of the intercom, and thinking to stick the switch out from there to have the flexibility to swap output. I will test using the current speaker I think but not sure if there is something I am missing here, and on the fence for changing the speaker as well.
I have been doing more research came with the an idea to retain the original device function. I am thinking using a 4PDT switch, wire the original radio/intercom and a google home mini to the 1 output speaker (maybe 2 speakers, but not sure if this will then also require an amplifier or some other things). In the image attached, thinking to just cut that line and add in the switch there and wire in the google output into the switch as well. There is a hole at the bottom of the intercom, and thinking to stick the switch out from there to have the flexibility to swap output. I will test using the current speaker I think but not sure if there is something I am missing here, and on the fence for changing the speaker as well.
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Bad ideas all around.
There is no cut and dried solution with that system, sorry.
You're attempting to mix that google thing with old technology, and it's simply not going to produce acceptable results.'
Plus, the impedance factor is against you. - 4 ohms and 45 ohms is wildly different animals.
Can you clarify which part is it's a bad idea and why? From what I understood it is acceptable to connect speakers of higher ohm load to an amplifier. So in the case of the googles 4 ohm default should be fine when hooking up to the intercom 45 ohm speaker right?
I can understand there potentially being an issue in lets say swapping the intercoms 45 ohm speaker to an 8 ohm as it is lower. In that scenario would it be possible to wire in an amplifier or some device to match them together?
Your best bet would be to tap audio off the mini and feed it into the "phono" input of that intercom system.
I'm just starting on a plan to replace the guts of the nutone system in my 'new' house. It's an older model than yours, 1965 vintage, has only an AM radio, and is tube based. The difference for me is that I do still have all the stations around the home (8 of them plus the base station). My primary goal is to still use it as an intercom occasionally, but primarily as a whole home music system. Music is likely to be fed from a Raspberry Pi embedded into it (running as a Squeezebox client). The trick will be dealing with the speaker impedance of the remote stations, and each of them having their own volume control changing that impedance. A not only do I need to build the right power amp for it, i also need to have a mic preamp for when being used as intercom.