Curtis-Mathes HiFi

[roivett]

I recently picked up a Curtis-Mathes HiFi console and wondered if it would be worth restoring. The cabinet in satin Walnut finish and minimum scratches/blemishes. It will clean up nice. I do not know how to determine the type of chassis but it had the numbers 648210 stamped on the frame and the numbers 33B8MX painted on the side. Output tubes are 6BQ5. All tubes are C-M. It also had a date painted on a part of the cabinet frame (1964). There are Two HUGH side firing speakers (12" plus) and four 5 inch mids facing forward. The TT in Curtis-Mathes brand (Made in England). I hope this will be worth the effort to restore as my hope is that it will kick out some jams. Am I fooling myself? Also, where can I obtain a Variac cheaply?


Roivett

 

[Tom Bavis]

The Sams index lists a 33BMX (#700-7) and a 33C8MX (#815-5) - probably one is close. Your library may be able to get these for you. Soemone here may have them - I have mostly pre-'64.

 

[Thatch_Ear]

Sounds like the TT is a Garrard. Popping something better in there should be easy if it isn't a real nice ones. Garrard made millions of TT over the years that were basically the same size and might have had the spring loaded feet in the same place so pulling out one and popping in another that has a beter tone arm and you can change cartrides on. Consoles tended to have pretty cheap TT in them.

If you can't find a variac local you can get then on Ebay. They are pretty heavy so shipping might cost as much or more than buying it.

Here is one made by Calrad. I used to have on like it and it is a good variac. If you can get it for 20 to 25 $$ after you pay shipping it would still be less than half of a comparable new one. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=71391&item=7515350299&rd=1

I just happened to see it a couple of days ago when I checking to see how Hot Gas' auction was going.

I have the OPTs from a SE 6BQ5 CM that I put into a DIY. They are of a good size and have good bandwidth for SE in a console. I don't know what the number was but the thing was a reciever. It was trashed when I got it, only the transformers worth keeping, so I don't know the model number or what the console looked like. I bet it sounded good though.

 

[roivett]

Thanks for the information to all that responded thus far. I have taken the unit out of the console and made a map of the tube locations and numbers. I live in rural Alabama and I guess my next step is to find someone to test the tubes (right?). I have to admit to being brand new at this restoration stuff. I'm also trying to find a site that has Sams photofax schematics, if anyone has any suggestions. I'm really anxious to get this thing fired up and into action. It looks like I should be able to connect my current TT (Sony PS-X600 w/ Micro Benz cart) through the "Tape" input.

Other Stuff:
Sequera MET7
TDL RTL3 transmission speakers
McIntosh MR77






Later
Roivett

 

[Thatch_Ear]

You can put some light sockets on a board in parallel and the higher the wattage bulb and the more that are in the sockets will result in greater voltage drop. A quick trip to the lumber and hardware store and a bit of time you can build something that will do the same job as a variac. Just put the sockets in a chain and wire up a plug at the other end. With a voltmeter you can adjust the voltage through the number of and wattage of the light bulbs.

Not as easy to use as a variac, the result is the same.

 

[Thatch_Ear]

And yes, testing the tubes would be the 1st step. Make sure that the tubes go back in the same sockets so you don't mess up the allignment of the tuner. The preamp and power tubes don't matter much, but the tuner section needs this. Hopefully they are all good and often changing out a 6AU6 or two won't change the allignment and you can use it without taking it to a tech.

 

[outlawmws]

You can put some light sockets on a board in parallel and the higher the wattage bulb and the more that are in the sockets will result in greater voltage drop. A quick trip to the lumber and hardware store and a bit of time you can build something that will do the same job as a variac. Just put the sockets in a chain and wire up a plug at the other end. With a voltmeter you can adjust the voltage through the number of and wattage of the light bulbs.

Not as easy to use as a variac, the result is the same.

You don't use the bulbs in parallel, and you only need one.

The other thing is the lower the wattage the higher the resistance.

Get your self a light socket, A duplex receptical, and a power cord, some wire, and I added a GFIC in front to make it as idiot proof as possible. possibly better than a light socket is an old fashoned screw in fuse holder. Yes they still make them! :yes:

Wire the power cord to the GFIC, (white to solver screw, Black to gold) or if you choose not to use the GFIC, Wire the black to one post on the light socket (Or if using a GFIC, use a wire from the side of the GFIC that goes to other circuits to be protected to the lamp socket). Wire the other light socket post to the gold screw on the duplex (putting the lamp in series). The white wire on the power cord (or the White side of the GFIC) goes to the silver screw on the duplex.

Now anything plugged into the dupex has the lamp in the socket as a resistor in series. I like having the GFIC as it also give me a handy full power outlet where I'm working. Be sure to mark the recepticals so you know what your plugging into. :yes:

You will also find the lower the voltage the less power a tub amp puts out. :scratch2:

Low lamp values give high resistance and lower voltage. high lamp values give low resistance and higher voltage,

I measured some at load and got these results:


Dim bulb tester - Bulb ratings and results.
Load Motorola Mono Tube amp, .62 @ 117VAC

bulb wattage ohms resistance resulting Voltage @121VAC input
40 26 67
60 19 81
100 10 91
150 7.5 100
240 5 110

This wont line up in colums but you get the idea...

I'd start with the 40 to begin.

 

[outlawmws]

Don't know if this will show properly, if not I'll delete it

receptical(gold screw)------Lamp socket---------Black 110 wire---------power plug

receptical(Silver screw)-------------------------White 110 wire---------power plug

OR

receptical(gold screw)----Lamp socket---GFIC out|==| GFIC in----Blk 110 wire--pwr plug

receptical(Silver screw)---White 110 wire----GFIC white/silver neutral post----pwr plug