Help setting up a vintage McIntosh system

phono leads to phono input C-20
phono ground wire to ground terminal C-20
C-20 Main output to MC240 input
MC240 left output COM and 8 ohm to the speaker
MC240 right output COM and 8 Ohm to speaker
Using any kind of lamp cord, speaker wire or whatever, the wire should have an indicator for the conductors such as one side is ribbed. Do both speakers the same. Hooking the COM to speaker Black would be the usual way but some use the red. Just both speakers the same or you will lose bass response.

phono power cord to c-20 switched or unswitched, your choice.
amp to either, too.

ALWAYS Preamp on first then you can turn on the amp. Give this one a few seconds to let the preamp settle down. I don't know if there is a delay in switching on the outputs. Manual should talk to this.

Always amp off first, then you can turn off the preamp

Don't want odd noises from the preamp switching going through the amp to the speakers.
 
Non of this has been serviced? How long has it been sitting? Good possibility that just plugging it all in will release some magic smoke and do some serious damage.
Go to the tube forum, they will guide you through bringing up long dormant gear.

BillWojo
 
Use the twin inputs on the 240. Set the master volume at one' o'clock on the pre-amp. Then start with the twin controls off and slowly advance the twin volume controls to 11 o'clock or until the volume is a touch louder than you like to listen with your favorite type of music.. If the sound is to loud back down the volume on the power amp equally, if not advance the twin amp controls toward 12: 0'clock position. . . When finished you should have the Master volume control between 10 and 12: o'clock for normal listening. And there should be no hiss coming out of your speakers. Week signals from some Classical recordings may require you to advance your volume control as high as 2 or 3 o'clock, and there may be a touch of noise in the back ground in that case. Its not unusual for settings to change with the recordings, your personal tastes, types of music or how you feel that day. . So we re looking for a pleasant compromise with the preamp control set around 12:00. Why 12: because that gives you the best performance when you want to use the loudness function, too when listening to music at very low levels with the master control set below 9:00.

There were so many different LP recording companies that each had their own idea as to what was perfect reproduction could also add to the issue. Its a lot easier today with digital formats. Home theatre is usually the easiest of all, though there are always exceptions. In analog the exceptions were the rule. Just look at the choices for EQ curve for different LP's . Signal to noise was a big issue in the 60's . Today we have plenty to be creative with, back in the 60's it was an important issue in all types of sources. So getting the settings just right for your listening space and choice of speakers is very important. for a great listening experience. Mcintosh was unusual in that they preferred using 2.5 volt sensitivity for their amps via the Stereo inputs. Other companies used 1.7, 1.4, 1.0 and .75 volt as normal operating levels. Today we have as much as 20 to 25 db more signal to noise ratio for phono inputs, and the new electronics can sustain higher peak levels increasing the the dynamic range.
 
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