CMI Electronics SG 215 Power Amp

Some facts on the SG Systems amps:

Made generally in 1974.

Made at the old Standel plant in El Monte,California when Chicago Musical Instruments (CMI) purchased Standel.

Because Gibson Guitars and CMI wre both owned in 1974 by Norlin, Gibson has inherited the old SG Systems documentation.

Gibson customer service can provide owner's manuals, schematics, parts lists, and service manuals. See Gibson's website.

SG Systems really only made three amps. They made a PA system, a bass head (100B) and a guitar head (100G). The speaker cabinets were just different sizes. The SG-215 was a cabinet with one Eminence 15" and two Eminence 10" speakers. My SG-215 has the 100B bass head.

The bass and guitar heads have a "notch shift" feature that was used to simulate other amps. For example, the 300 setting was for Fender and the 450 setting was for Standel.

The guitar head has a Maestro phase shifter built into the amp.

All the SG Systems amps sound great because of the pair of 8417 output tubes. These tubes were mainly used in very high end audiophile amps. The tubes operate at unnecessarily high voltages. (My amp has had apower transformer and choke replaced). The great part about these tubes is that the two output tubes put out 100 watts.

The there are only two bad points about the SG amps. The first is that they use the 8417 tubes. They are very rare and are only available as NOS U.S. tubes. (My SG originally came with RCA tubes, two 8417's and one 12AX7A. All the original tubes are still good). The second bad point about the SG Systems amp is that they are very heavy. The cabinets are made out of 3/4" particle board with steel edging. All cabinets therefore came with casters.

I basically love this amp. It has been good to me for over 28 years.

See above. I use my SG as a keyboard amp.

See above. The 8417 tubes put a lot of strain on the amp's transformers.

See above. Gibson customer service has been great for a product they didn't even make.

See above.

This amp rocks it was made around the time punk rock was introduced.I dont use the amp features but I use a effects processor through it and it sounds perfect.

It has a perfect mix I use a high gain effect that sounds similiar to a marshall tsl 100 stack.This amp realy gives you good treble and stuff.It puts out what you need.

I can depend on it it really sounds awesome.I accidently knocked it over once and it didnt do a thing to it so I see it as a versitile tube amp.

I was given this amp.My dad knows everything about these kinda amps so hes made the repairs on it and I repainted it and rewired it.

I am Will Newberry I am 16 years old and I lead a youth worship team.I use my SG-212 guitar amp every Saturday and Wednesday when we play and everyday at home.I play a lefty fender standard strat with normal single coil pickups.I use a Digitech Rp 200 as my sound.It makes a great duplication Of a marshall tsl 100 watt amp.It makes a great punk sound.

SG System ?? 2 seperate channels with one Master Volume both having seperate Tone and Base adj. Front Pilot Light, LO and HI inputs for both channels. Channel #2 has Reverb and waveform. There is a seperate area for Notch and Shift ajd. ( 300,450,600,700 ) There is a MID and ACCENT control as well. 3 seperate Phase Shift selections for LOW, MED and FAST. Label above this section states " DYNAMIC VOICING " ***** My Amp actually says model SG-212.

All I can tell you is that today I was hit with a blast from the past. I acquired this amp 4 years ago in a trade for tools ect from my oldest brother. He had picked it up in 1980 as a friend owed him money. It has been UN USED for over 24 years -- No B.S. It sat in the corner of a storage unit in Colville WA. I needed money for business taxes and took it into Green River Music of Auburn WA. This thing is so heavy you can barely get it out of the vehicle without requiring a quick stay in the hospital for getting a hurnia. The guy I spoke to earlier over the phone was happy to see me bring it in. He quickly took it to the back and I finally got to where he was, he was just plugging in his electric guitar. He started out real mellow playing a couple cords to see what did what. Within 3 minutes this guy was induced with excitement. He progessively kept getting louder and louder and this AMP sounded better and better. I got lost in the music as this guy was good !!!! I then noticed we had the entire store of people within 3 feet of us. With each adjustment came more power and different sounds. I felt like I was back 24 years at the Eastern University campus where I was just 9 years old watching FAST WAY play trying to sneak a drink of beer from the people next to us. I am not kidding you -- THIS THING ROCKS BIG TIME !!!!!!!

As mentioned it has sat for a very long time. The guy who played the guitar stopped, looked up at me as if to say " HOW MUCH DO YOU WANT ". Instead, he turned all controls down, unplugged everything shut it down and said " Sounds O.K. " I said bullshit -- that sounded awesome. He asked if I was going to want them to sell on consignment. At that time, another store clerk came over and said " That looks like an OLD one ya got there ". Best we could do is about $ 100.00 I was going to say what I actually had on my mind, then decided to do otherwise. " I will need to think on that - Maybe I will be back next week. " The guy who played the guitar followed me all the way to the door and watched me through the glass as I put the monster in my 1996 Ford Minivan. He was still looking at me as I drove away. I did slip him my business card to have him call me if he found someone who was interested in paying $ 300.00 I have a feeling that I will hear from him soon. I also think he may end up as the buyer.

I was not able to find anything about the company. They were located in EleMonte California.

If there is anyone out there who ever reads this message, you to can smile knowing that this is a very rare Amp with only a limited production of units made. Why it sounds so good is beyond me. I am now beginning to consider storing it for another 20 years. It should then be worth a lot more at that time. It is flawless right now.

(NOTE: I do not intend this to be a "for sale" post, but I would like for it to find a good home if it's worth anything to anyone.)This is a tube amp, with a sticker inside the chassis "April 17, 1974 SG100B". I picked it up for parts at a flea market. It was a bare amp, obviously removed from the case / speaker. It was missing the two output tubes (chassis unmarked) but had the driver tube (12AX7). I was really only interested in it for perhaps the transformers, as I am not a musician, rather, a tube amplifier repair hobbiest. I tried a set of 6550 output tubes, but it was immediately obvious that they were not correct because of the rather low bias voltage. Checking my tube manuals, I correctly deduced that it used 8417 output tubes. I had several new ones, so tried them. The silly thing came right up and works fine, much to my surprise. All the capacitors are original, but would not be too difficult to replace them. Operating at 675 volts on the tube plates, this thing should do a very solid 100 watts or more!!

The amp features are similar to the 415 reviews submitted here: Two input channels, each with a hi and lo jack and individual volume / bass / trebel. There is "Master" volume. There is a "Notch Shift" with four selections: 200 - 300 - 400 - 500, a variable "Wave Form" and a variable "Mid". On the back is a jack for "wave form", external speaker, and signal line. There is a short pigtail wire with a standard RCA female jack for the cabinet speakers. The pre-amp / affects section is all solid state. As far as I can tell, the inputs all work.

Sadly, I doubt the amp is worth the cost of a new set of 8417 tubes. They are quite rare, and similar to another post here run about 80 bux IF you can find them. I'm not sure I want to let a set go.

I hate to junk this amp if it has any value to anyone, but I sure don't need it either.

Judging from it's brush with the junk yard, I'd say it must be pretty good to only need output tubes!