Does anyone know the Mcintosh C20 diffs?

[clinic-audio]

Here is the project I've made 8 years ago for a customer request .
This front glass is with a very rare font
I have them in pictures in attached files
one is original front glass before I touch it (note that the 5 big circles are not clear on this model)
second one is the same front glass restored
thirst printed paper project

 

[clinic-audio]

and now a picture coming from C20 owner's manual : the font of the front glass is 100% identical to the one I've posted one minute ago !

 

[VintageMac]

"One of my C-20s has a main output pair of RCA jacks
The other C-20 with same appearance faceplate has two pairs of main output RCAs"

As best as I can determine units prior to 6L999 had just one main output pair. There was one switched and 3 unswitched outlets, and a dim/bright pilot switch.

After 7L001 the units featured a single L+R output and two main output pairs. There was one switched and 4 unswitched outlets. The pilot switch was eliminated.

Larry

 

[gmfgmfgmf1]

"One of my C-20s has a main output pair of RCA jacks
The other C-20 with same appearance faceplate has two pairs of main output RCAs"

As best as I can determine units prior to 6L999 had just one main output pair. There was one switched and 3 unswitched outlets, and a dim/bright pilot switch.

After 7L001 the units featured a single L+R output and two main output pairs. There was one switched and 4 unswitched outlets. The pilot switch was eliminated.

Larry

Thanks for the info

 

[number6]

I see this thread spans several years but there's some recent posts, so maybe someone can help.

I acquired a c20 early version that does not have the brass frame, the plastic, the volume plate, or the plates that attach the front panel to the chassis. I contacted McIntosh Labs, and Audio Classics and neither has the brass, but Audio Classics has the glass. I know I can also get the plastic or glass from Radio Daze. Is there a place that would fabricate the brass frame and volume plate? I contacted Larry from RR Artifacts, and he suggested fabricating an aluminum frame, but I am not sure of the exact dimensions to hold the glass and volume plate. I'd consider using rails and endcaps with the earlier version if the holes lined up, but not sure if they do.

Anyone help would be appreciated.

 

[s-petersen]

A few pics may help. There are a couple of ways to go depending on what your goals are.
IF you are just going to use it, not considering collector value, you can modify yours to fit a newer faceplate, if you are trying to restore as a collector, it's going to be hard finding exactly what you need. The upper and lower aluminum frame parts for the "late" unit are available from Audio Classics, they were $25 each a few years ago.(upper and lower are the same IIRC(you would have to modify your top and bottom cover to make them fit)(drill 3 holes each)The late side plates should fit your unit with the aluminum top and bottom frame parts.The available end caps should fit with the frame parts.The larger aluminum plate could be made in a trophy shop(out of brass)
If you need measurements of any parts, let me know.

 

[number6]

Thx for the reply. I'm keeping the c20 for my use to match with my mc240 and mc60s. All updated with new caps and sound great.

From the pics you can see the top black piece and bottom aluminum piece don't extend to the faceplate. Audio classics said the faceplate did not attach to chassis but rather the wooden box. I think it's like the mr55 tuner which also had a brass frame.

I like the brass frame but I like the newer glass over the plastic with the brass bar. Ive seen on radio daze that there are two heights for the newer versions 4.5in and 4.9, I think. Also, Ive seen someone on bay who fabricates volume plate for newer c20 but not early version with brass frame.

If I were to use the new glass what mods are necessary to fit this early chassis? Do the potentiometer wholes line up?

 

[s-petersen]

The newer faceplate attaches to the unit using the side plate and top and bottom cover, yours is another variation You may use an extension plate for the top and bottom,using longer screws to mount them to the preamp. Everything lined up on my 2 units, but I didn't have the brass one to compare it to.

 

[s-petersen]

If your unit measures 4.5 you would need the common side plates (R,L)the aluminum frame upper and lower(I think they are the same) ($25 EA)The volume plate ~5 inch Glass ~5 inch and fabricated upper and lower extensions

 

[number6]

The height of my chassis is 4 3/8in high and 14 1/4in wide. How long are the rails that hold the glass on yours?

 

[number6]

This is what my version should look like. As you can see the brass frame is a solid piece. The newer version uses rails and encaps. Do you know if the holes of the 4.9 inch glass lines up with holes of holes of the 4.5 glass?

http://www.hifirelics.com/Starsky10 Pics 3.13.13/mcintoshc20-A.jpg
http://www.hifirelics.com/Starsky10 Pics 3.13.13/mcintoshc20-B.jpg
http://www.hifirelics.com/Starsky10 Pics 3.13.13/mcintoshc20-C.jpg
http://www.hifirelics.com/Starsky10 Pics 3.13.13/mcintoshc20-D.jpg

 

[s-petersen]

The side plates, or the upper and lower aluminum rails? I am at work, I can measure tomorrow.

 

[s-petersen]

This is what my version should look like. As you can see the brass frame is a solid piece. The newer version uses rails and encaps. Do you know if the holes of the 4.9 inch glass lines up with holes of holes of the 4.5 glass?

http://www.hifirelics.com/Starsky10 Pics 3.13.13/mcintoshc20-A.jpg
http://www.hifirelics.com/Starsky10 Pics 3.13.13/mcintoshc20-B.jpg
http://www.hifirelics.com/Starsky10 Pics 3.13.13/mcintoshc20-C.jpg
http://www.hifirelics.com/Starsky10 Pics 3.13.13/mcintoshc20-D.jpg

The holes do line up.

 

[number6]

Yeah, the aluminum rails. At audio classics they have a universal rail at $60, end caps $66. Glass $199.

 

[number6]

Measurements for both the upper and lower rails as well as the side plates would be appreciated. This is really helpful. I'm getting a better idea how I'm going to finally put a faceplate on my c20.

 

[s-petersen]

Both rails measure 14 9/16", if you are using the larger faceplate, call it standard, the standard side plates measure 1 5/8 x about 4 1/8, it's an irregular shape there are pics earlier in the thread. You don't have to extend the upper and lower covers to support the faceplate, the side plates alone can do it, especially if it's in a cabinet.
Tomorrow I will be making the 4.5" end caps, A friend with a CNC shop is letting me play.
The only thing i have to figure out is how to do the surface treatment.

You are lucky yours came with the dial pointers, I had to 3D print them, another friend had a 3d printer, and we made them. The project was stalled until the 3D printer came along

 

[s-petersen]

Does Audio Classics have both sizes of glass? When I bought mine, they only had the shorter one,and the volume plate to match, which caused me to go in that direction,which is why I have to make the shorter end caps.

 

[s-petersen]

Now I understand what happened to your unit,apparently, originally the faceplate was mounted to the cabinet, before they started mounting them to the chassis. I found this pic online

 

[s-petersen]

I've been busy today at my friend's CNC shop. New end caps! I still have to polish and find a place to bright anodize them. The first one took several hours to make(program, setup)the others 5 minutes a piece.

 

[number6]

Wow, those endcaps looks great. I'll have to find out what sizes are available at AudioClassics.

Since I like the brass frame I did some research to see if McIntosh made any other product with the brass frame thinking I could salvage it from another product. The MR55 tuner has the brass frame with the same dimensions 14 3/4in wide and 4 3/4in high. Unfortunately, it cannot be used interchangeably because the MR55 faceplate is one solid piece and is not simply a frame.