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Thursday
Aug092012

A Brief History of NuTone Intercom Systems

Part 1

In order to understand NuTone intercom system designs you need to understand how the systems fit onto a time line. NuTone system designs were evolutionary, meaning that new models were based on the previous models, but with new features and better technology.

NuTone would design a “platform”, which was the fundamental building block that every model would use. By adding features to the platform, new and different models would be created.

NuTone intercom systems can be divided into different groups based on the type of wire each platform uses. There are two main wire types: 3-wire systems and 6-wire systems. These two wire types comprise about 80% of all NuTone intercom systems.

There are a few exceptions with regard to wire types. NuTone has also made 5-wire, 8-wire and 4-wire systems.

Another design consideration with NuTone intercoms systems is how the wiring is laid out and installed. There are two types of wiring schemes that are used with NuTone intercom systems. They are Home-Run systems and Loop-Wired systems.

Home-Run Systems: In a home-run wiring layout each remote station (entry door, inside and patio) has its own individual cable with the appropriate numbers of wires in the cable (3,4, 5, 6 or 8 wires) and these cables all run directly back to the master station. As an example, if there are 9 remote stations, there will be 9 cables behind the master station. Home-run systems comprise 80% of all NuTone systems.

Loop-Wire Systems: In a looped-wired system, there will be multiple stations on a single cable of wires. As an example, if there are 9 remote stations, these may be grouped onto 3 cables. Cable #1 may have 3 stations, cable #2 may have 4 stations and Cable #3 may have just 2 stations. Behind the master station you will only find the 3 cables. NuTone loop-wired systems use either 6 or 8 wire cable.

One thing to keep in mind is the following rule: NuTone intercom models that were designed to be Looped-Wired systems can be looped-wired or home-run, either layout or a combination of both will work. NuTone intercom models that were designed to be Home-Run systems can only be installed with Home-run wiring, no exceptions.

All of the original NuTone intercom systems were vacuum tube designs, and all vacuum tube models are 3-wire systems with one exception (model 2400, which is a 5-wire, home-run Stereo Music Intercom System).

The first model to use solid-state electronics (transistors and diodes) also used a different wire type. It was the model N2561-2562. This revolutionary model was a huge design step forward for NuTone and was an 8-wire, loop-wired system. The N2561-2562 was in production from 1957 through 1974, that's 17 years!

A quick note about early NuTone model numbers: In the early days, NuTone used model numbers like 2011-2012. The 2011 and 2012 are basically the model except the finish (color) of the model was different. For example, the 2011 had a silver faceplate and the 2012 had a copper-tone faceplate. This is the way NuTone labeled their Intercom models until the mid 1970's. After 1974, NuTone added letters to the model number to denote the finish of the intercom. For example a IMA303T (traditional) was a dark walnut finish, and an IMA303L (light) had a light maple finish.

The last year of production for vacuum tube models was 1966. Since then all models have solid-state electronics.

Vacuum Tube 3-Wire Models:

1954 – 1966: 2011/2012 2013/2014 2015/2016 2053/2054 2055/2056 2057/2058

 

Vacuum Tube 5-Wire Model:

1957 - 1962: 2400 Stereo Music Intercom

 

Solid-State 3-Wire Models:

1966 – 1971: 2067/2068

1968 – 1975: 2090/2091 2063/2064

1975 – 1983: IM203/IMA203 IM303/IMA303 IM323/IMA323 IM313/IMA313 + B,C,D

1984 – 1994: IM2003 IM3003/IMA3303 IM3103/IMA3103

1994 – 2006: IM3303/IMA3303

 

Solid-State 5-Wire Model:

1966 – 1972: 2071 Stereo Music Intercom

 

Solid-State 8-Wire Model:

1957 – 1974: N2561/N2562 2500

1975 – 1983: I600 SM428

 

Solid-State 6-Wire Models:

1965 – 1975: 470

1968 – 1975: 2540/2541 2542 462

1975 – 1985: IM406/IMA406 IM806/IMA806

1986 – 1995: IM4006/IMA4006 IM5006

1996 – 2006: IM4404/IMA4406 IM5000

 

Solid-State 4-Wire Models:

1997 – 2004: IM3204/IMA3204 SR9000 Stereo Music System

 

Finally we have to include the rarest NuTone Intercom model ever made, the IM6106. Originally the IM6106 was scheduled to be released in 1988 but due to design and manufacturing problems, the release was delayed many times. There were about 400 pre-production units released to dealers and installed in homes. For the next 3 years, everyone struggled to keep these units working until finally the model was dropped and all of the 400 units were replaced at NuTone's expense. If you have an IM6106 you have a rare and unrepairable unit.

 

Reader Comments (105)

Chris,
Thanks for the guidance. I really only expected T9 would be bad if it was a common defect found in the field over the years. Based on your statement that you've never replaced one, I changed my approach. I fed 1KHz from the collector of T10 and compared it to a direct connection to the speaker and T9 certainly looked good- I should have done that instead of bothering you.
I hope I caught you before you desoldered one to check the primary reading.

Anyway, it was C53. The master station appears good on the bench. I'll install it to test in the house, then I plan to modify it; remove the cassette and affix a Sirius receiver and ipod base. The power transformer (T10) is also blown, I've been testing with a bench DC supply, so that's next.

Again, thanks for your website, this would have been 10 times more difficult without the service manual. I'll put an entry in your guestbook after I get this system reinstalled and completed.

A Thousand Thanks,
Ed

February 28, 2015 | Unregistered CommenterEd

Hi Ed,

I'm glad that you found the source of the problem, a full recap is usually in order for these models.

The can capacitor should be restuffed and opposed to replacing it with individual components.

Chris

February 28, 2015 | Registered CommenterCindy & Christopher

Chris-
We have a home built in 1992 that has a working IM-4006. We had the same model at our last house and I replaced it with a IM-4406 unit in order to get a CD player and more modern appearance. I'd like to do the same in this house, but Nutone no longer makes the 4406. The replace kit they do offer through Home Depot is way too expensive (I have 12 satellite speakers and 2 door units). Any idea where I can pick up a working IM-4406?
Mark

March 2, 2015 | Unregistered CommenterMark

Hi Mark,

If you're looking for a 4406, you would want to look for an IMA4406 (not a M4406). You will also need a IR105 Rough-in kit and since you have 12 remote stations you will need a IAA440 Expansion Kit.

Finding all of these items will be a lengthy project since all of them are discontinued items.

I will caution you about buying a used Master Station from a private seller. The IMA4406 are not without their own specific problems and many of them will need some repair (perhaps sooner than later). The biggest risk are Master Stations that may have Micro-Controller problems, these units can be very expensive to repair (if repair is even possible),

As for Masters that are being sold as NOS - beware and make sure that the units can be returned if they do not work. Many of these so-called NOS units are actually units that were defective when they were new out of the box and after they were replaced under warranty by NuTone, the defective units were never returned.

If you're buying a "refurbished" unit, you need to ask exactly what was done to refurbish it. If the Power Module was not rebuilt for the common failure issues, then the unit will likely not be reliable into the future. A "refurbished" Master should have at least a 1 year warranty against any problems, including the CD Player.

Finding a IR105 is not to difficult, they seem to be around if you look. Finding a IAA440 Expansion Kit may be difficult because it was not an item that most dealers kept in stock, so there are less of them left over today.

Thanks
Chris

March 3, 2015 | Registered CommenterCindy & Christopher

Is Airking a brand or model of intercom. It is in a 1963 house. It has separate music speakers and intercom speakers. The main unit will not power on.

April 27, 2015 | Unregistered CommenterCeORY

Will a nutone N2561b retrofit an n2651/2.

April 27, 2015 | Unregistered CommenterDennis

Hi Dennis,

All Model N2561 & N2562 are interchangeable. The N2561 "B" you asked about is just a common way of referring to the Master Station itself.

The Wall Housing was packaged in the "A" carton and the Master Station was packaged in the "B" carton when the equipment was new and in production.

Thanks
Chris

April 28, 2015 | Registered CommenterCindy & Christopher

Hi CeORY,

Yes, there was a company called Berns AirKing and they made a few models of Radio Intercom systems. I've never seen one in person and I don't know much about them.

Thanks
Chris

April 28, 2015 | Registered CommenterCindy & Christopher

Dear Chris:

I got a few more questions regarding the long lasting 2560 series:

1.- How does the 2575 Clock Speaker mutes the music ? How does it silence the music throughout the system ? Does it turn the entire system to Stand-By Mode ?

When the alarm is "set", the radio mutes without affecting full-time use of Intercom, however, does it affect the Electronic Chime sound throughout the speakers ? The electronic chime can be heard throughout the speakers only on Radio/Intercom Mode, it does not play on Stand-By Mode nor Monitor Mode. So, when the speakers are on Radio/Intercom Mode, will the Chime play on them when the alarm is "set" on the 2575 Clock Speaker ?

2.- Chassis A to D are heavier, made of germanium based transistors. Chassis E to L are lighter, made of silicon based transistors. Does it affect the sound quality ? Is it true that germanium transistors bring a "finest" vintage sound that is difficult to obtain nowadays ?

3.- The long-lasting 2560 series permits at least 16 speakers. Does it make a difference whether all these are 8 inch speakers or 5 inch speakers ? Do larger speakers consume more power than smaller ones ? The more quantity of 8 inch speakers installed will cause a decrease of the System Volume of the Master Station N2561/62 ?

4.- "Built-In" speakers are the best speakers because the walls act as an "infinite baffle" bringing the highest fidelity sound. The 2576 Outside Surface Mounted 8 inch Speaker is exactly the same as an ISA-77 with a 45 ohms speaker cone. The 2574 Surface Mounted Horn Speaker is a 5 inch Speaker with a horn attachment that amplifies the sound, the horn would act as a baffle too, I guess ?. I think that the 2576 (or ISA-77) doesn't have a baffle. Does this make the 2576 (or ISA-77) a lower quality speaker ? Which sounds better, 2574 or 2576 (ISA-77) ?

5.- The 2560 series is an 8 wire system. The black and black/white wires are the ones that manage the outside (door) communication. My patio speakers are out of reach and located about 20 feet away from their remote controls. That's why I find completely useless to connect the black wires on their remote controls. Everything seems to be alright with the black wires disconnected on them. Is this OK to do ?

Thank-you very much.

May 22, 2015 | Unregistered CommenterLouis

Hi Louis,

1. There is no technical information about the Model 2575 Alarm Clock Station and I cannot find a schematic of the station itself, so I have no detailed information about how it actually works. I do not have a 2575 here, so I have no answers for you about it.

2. Whether Germanium or Silicon transistors produce "better" sound quality is a matter of personal preference and belief.

3. The maximum number of remote stations on a 2561 System is 16. An 8" speaker cone will require more current because it is working harder to move a greater volume of air. Since the 2561 was designed to accommodate this number of stations, it is unlikely that there would be any noticeable decrease in volume

4. Since I have no way to test these speakers side-by-side, I have no idea which 'sounds better". The notion that some speakers use in the 2561 system are "higher" or "lower" quality is splitting hairs.

5. I see no reason to leave any wires disconnected anywhere in an installation.

Thanks
Chris

May 26, 2015 | Registered CommenterCindy & Christopher

Hi Chris:

Thank-you very much for your guidance.

1. Since we don't have information about the 2575 of the 2560 series, the closest model that might operate the same way is the Clock Timer of the magnificent ultra-rare Nutone 2542. Please, any info that you know about how the 2542 clock silences the music and whether or not the Electronic Chime operates on the speakers when the alarm is "set", would help me solve the mystery of the 2575 since the mechanism and operation probably might be the same.

2. Thanks for your response.

3. Thank-you very much !

4. Well, in my experience I can tell you that the best speakers are the early 8 inch "built-in", that is the 2572, 2573 and the Master 2561 9x6 inch, then in second place the early 5 inch "built-in" speakers: 2570, then in third place the 2574 Horn Speaker and in last place the later 5 inch speakers made in Mexico. In my opinion, "built-in" speakers sound better than surface mounted.

5. Thanks.

Thanks indeed !

May 26, 2015 | Unregistered CommenterLouis

Hi Louis,

I have already looked through the 2542 Manual, there's no specific information or schematic for how the clock control works

Thanks
Chris

May 26, 2015 | Registered CommenterCindy & Christopher

I have a Nutone IM-203 system in the house I purchased and need to replace the master unit. Would the Nutone IM-3103 Be a compatible replacement? I see they are both 3 wire systems> Thanks.

John

October 29, 2015 | Unregistered CommenterJohn

Hi John,

No, the IM3103 is not a suitable replacement for your IM203.

Your remote stations are designed to work only with a IM203 or IMA203.

If you installed a IM3103, you would have to replace all of your remote stations with IS305 inside remotes, IS309 Patio remotes and the door speaker with a IS67

What is wrong with your IM203?

Please let me know

Thanks
Chris

October 29, 2015 | Registered CommenterCindy & Christopher

Dear Chris:

1.- A part of my home intercom wiring is unfortunately a kind of "Thermostat cable". This cable does not reach my 2570-B speaker located on my kitchen. So, I "extended" this cable using "choc blocks" joining it to an original 8-wire Nutone cable. Is this Okay to do ? I tried the smallest choc blocks I could find. This incomplete Thermostat cable has always brought me issues. Before using "choc blocks", I tried extending it with "electrical tape" but after a year of clean sound I started to listen interference and noises so I changed to choc blocks. Should I connect it with "choc blocks" or electrical tape ? What is the best way to do this connection ?

2.- Nutone says: "Up to 5 speakers may be jumpered together". This is not clear to me. Does this mean that no more than 5 speakers may be connected from each cable that connects to the 2561 Master Station ? Or just do not connect more than 5 speakers to any satellite speaker ? My wiring diagram is kinda weird. Only one 8 wire cable is connected to the 2561, but it connects directly to a 2570 (1 speaker) located 60 foot away which splits in 5: one for the kitchen (4 speakers), one for the dining room (2 speakers), one for the bedrooms (2 speakers), one for the patio (3 speakers). I want to add 2 more speakers to the kitchen section but it would be 6 (or 7 if you count the 2570), maybe should I add these two using the cable from the bedroom section instead ?

Thank-you.

November 28, 2015 | Unregistered CommenterLouis

Hi Louis,

Answer to question #1: I prefer soldering wires together over mechanical connectors. I would simply twist each wire together, solder the joint and cover it a small low-voltage wire crimp connector. After you have soldered and covered all of the splices, fold all of the splices back onto the cable and use electrical tape to cover over the bunch of wires.

Answer to question #2: First you have to be careful when using the Term "Speaker" and "Remote Station" interchangeably. The 2561 was designed to allow loop-wired or "daisy-chained" Remote Stations. The limitation is no more than 5 Remote Stations per cable run. If 1 or more of the Remote Stations on the cable are Wall Mounted Remote Controls (without a built-in speaker) it is allowed to have 1 Speaker connected the this type of Wall Remote Control.

I cannot tell from your description how many complete Remote Stations you have and how many Remote Controls (with separate speakers) you have on your single cable run.

Chris

November 30, 2015 | Registered CommenterCindy & Christopher

Dear Chris:

1.- Please can you show me what crimp connectors would you recommend ? Is there any chance of a video tutorial regarding this issue (soldering & wire splicing) in the near future ?

2.- Now it's all clear to me.

Thank-you.

November 30, 2015 | Unregistered CommenterLouis

Hi Louis,

Here's a link to the type of connectors I suggested: http://www.amazon.com/Dolphin-DC-100P-Super-Connector-Pcs/dp/B000JP7FIQ

I won't have time to make you a Video any time in the near future

Chris

December 1, 2015 | Registered CommenterCindy & Christopher

Dear Chris:

I have a minor problem with my N2561. It is the top control (Power and System Volume Control). Music turns On when I turn it to maximum (highest) level. At half or 3/4 level the system is dead.

Do you have any hints to solve this issue ?

As always, thank-you.

May 21, 2016 | Unregistered CommenterLuis DC

Hi Luis,

Your N2561 may simply have a failing control, or it may indicate a larger problem with the Master Station.

Typically a properly working N2561 will have more than enough volume when the System Volume Controls is set between 25% - 30%

You can try using just the littlest bt of cleaning in the control to see if that improves it.

Chris

May 23, 2016 | Registered CommenterCindy & Christopher

I have a music intercom nutone Scoville in the condo I move in the radio works all the room once the main one that is on the kitchen is on. Now am trying to see the intercom talk button works I push n it don't seem to work at all...what can I do so it work again. Also the front door one it seem like 2 wires r out not sure if when I open it is part of it or do it belong to a door bell....is not coming from the system is just out from a hole next to it..

December 20, 2016 | Unregistered Commenterana

Hi Ana,

I will need some more specific information about your NuTone system to answer your questions. The most important information is the actual Model Number of the system in your condo,

If it's easier, you can take some pictures of the Master Station, Remote Station and Entry Door Station and email them to me at: nscompany@msn.com

Thanks
Chris

December 21, 2016 | Registered CommenterCindy & Christopher

I have a Nutone IMA-4406 and am trying to connect a tablet or raspberry pi with a touch screen. I want to replace the front end of the Nutone so only the tablet or touch screen is mounted to the wall. I'd like to connect directly to the audio amplifier through the mini plug on my tablet or raspberry pi. I've searched the internet for a schematic with no luck. Do you know where the best place is to inject the signal or have a schematic?

Thanks for the help,
Rob

(Different Rob than the previous post; odd coincidence. Also, hoping this site is still monitored.)

August 11, 2017 | Unregistered CommenterRob

Hi Rob,

Your project is complicated and I am unclear about what you're trying to do exactly. If you wan to contact me directly I will try to answer your questions

Chris
925-743-8236

August 11, 2017 | Registered CommenterCindy & Christopher

Dear Chris:

After many years of nice work, my 2574 Horn Speaker went kaput due to low temperatures and high humidity in my country. Unlike other speakers from the N2561 series, it wasn't completely dead, actually it still played music but in a very weak shape, like a little 2 inch speaker.
I disconnected it, checked the impedance using a multimeter and read nothing. I found it very strange. I always felt very curious about what was inside of it, so I thought it was the perfect time to disassemble it.
I found out two things: It is a fantastic piece of vintage american engineering and the second thing is that Schematics are completely wrong.
Inside I found a unique 7 inch 45 ohms Cone Speaker, the negative pole is connected to a black wire that connects directly to another little speaker unit assembly located in front of the horn, the positive pole is connected to a Condensor or Capacitor (axial Capacitor NP Callins 3uf - 50V NP) and the negative pole of this is connected to the green wire of the little speaker unit assembly using a wire crimp. So, I found out both speakers are interconnected to a capacitor. I don't quite understand how that works.
My knowledge of capacitors is 0%.
So, I unsoldered the 7 inch speaker poles, checked the impedance using a multimeter, and Bingo, found out the speaker is dead. That's why the Horn produced a weak sound, only the little 2 inch speaker unit was working.
Fortunately, fixing 45 ohm speaker coils are not a problem to me. I fixed it successfully, soldered it back and now the whole Horn impedance show 45 ohms.
It looks perfect but I feel my job is incomplete. I feel tempted to leave the capacitor unchecked for another 50 years but I think it is not the right thing to do.
How do I properly check the capacitor using a multimeter ? Is it necessary to unsolder it ? I'm afraid of the 50 volts causing a shock. How do I avoid ruining the capacitor ? In case the capacitor is ruined, do I simply buy another axial 3uf -50 V capacitor and replace it ? Or do I have to charge it with 50 volts first ? My knowledge of capacitors is 0%.

Thanks for your time.

September 4, 2017 | Unregistered CommenterLuis DC

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