Martin Sigma GCR-7

Posted by Jeff Inglis on Sun, 09/10/00 - 04:01:50.

Greetings, I play a Martin Sigma model GCR-7, serial no. 7925, that is made in Japan. The new ones have different model names and are made in Korea. Could someone explain the GCR-7 and serial no. 7925 to me?

Thanx, Jeff

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Re: Martin Sigma GCR-7

Hi Jeff,
I have the same guitar also. I would like to know what the value is. I would like to sell mine, but have no idea what it is worth. It's in very good condition and was purchased back in the 60's.
If anyone out there has a ball park idea please e-mail me.
Thanks Gary

RE: Martin Sigma GCR-7

These early 70's Sigmas are rare and valuable. Grand Concert Rosewood. Solid spruce top with Rosewood sides back and neck. 7 is the highest grade wood you can get, and Japan just happened to have a large supply at the time. Very Good condition should bring you $650. But why would you want to get rid of it? Later ones made in Korea are just average crap. Ser# 7925 is a jackpot made in Japan.

Martin Sigma GCR-7

I also have a Sigma GCR-7 Serial #7634. I bought it at McCabes Guitars in Long Beach, CA in early 1973. I think I paid $140 for it. As far as the value of them, I see many Sigmas on ebay $400 to $700 all with 0 bids. Even some as low as $100 with 0 bids. The value of anything is only what someone is willing to pay for it. Mine has the value of nostalgia - my old hippy days. :)

Sigma martin guitar GCR-7 SN# 4933

I have a sigma guitar Model GCR-7 SN# 4933. When i was first learning i was using a very cheap guitar. I cleaned a house and the lady there had the Sigma She would let me borrow it often In 1987 she brought it to me and gave it to me for my birthday It has a beautiful sound My dad owned a Martin and he said this Sigma was very well made I would never get rid of it


Hi I just bought and original owner Sigma gcr-7
With case, factory string tag, and packet with truss rod adjusting wrench.
It is in very good condition, except few dings on the back of headstock.
But it is definitely laminate all around.
This has all of the indicators of 1970-1975. No zero fret, though so not first year.
5 digit serial #
The paper label is black on white background and a blue border, as indicated by any first generation sigma.
Proper gold sigma logo and the abalone m above it.
It does not have an adjustable bridge.
I'm just wondering if anyone has one with a solid top,
Please post a good photo showing the grain through
The sound hole.
It is to my understanding that all of the early sigmas are all laminate.
Are people jumping to conclusions, or are there any solid top models out there?
Thanks, Parry


I just got a Sigma GRC-7 recently with the low serial number 798*, a four digit number. Not sure about the year and such but the top is a solid spruce , the grain is clearly visible in the edges of the soundhole as a 'waterfall' effect with the grain dropping along the edges in a continuous fall. The back is solid rosewood and the grain on the inside of the back matches the grain on the outside....the sides might be a rosewood ply veneer, it's hard to get a good look, except to say that the inside and the outside of the sides are both rosewood so it's either a high quality furniture grade rosewood ply veneer or it might be solid. On the sides, with the curves needing to have more integrity with the bending process a good rosewood ply might be a better choice, but I don't know, I don't build them. and I can't tell. The instrument is in close to perfect condition ,looking like it was played in it's youth agressively with a few strumming type indentations at the bottom of the guard and then cased and closeted, which is how I found it. It's very light , beautiful neck with that slight edge that fits a hand so nice and the overall sound is comparable to my friends older Martin with just a tad less woodiness. I think that is because of the bridge having that metal adjuster deal, if the strings were in direct contact with a bone saddle instead of that adjustable thing it would sound as good,maybe better since the top is a tighter grained and higher quality spruce. As for build quality it is really good, the bracing could be trimmed but until I decide to put a new bridge on it it plays just fine. I have a newer Sigma also, a Korean one that almost replicates a Martin Dreadnought, but it is entirely ply veneer, even the top. It has a fine build quality, the finish is excellent with minimum checking and the interior looks like a real Martin with that center strip and the burnt in info but it doesn't have the same lightness in feel and that organic wood tonal quality is missing.

Sigma GRC-7

I have a Sigma GRC-7 that I got from a retired nun from the Catholic school I attended. I graduated 8th grade in 1975. Mine was made in Japan and has a five-digit serial number. It is definitely all laminated. I need to talk to the retired nun, who played in at least by 1972, but it could have been earlier. She took a vow of chastity, obedience, and poverty. I don't expect it cost much, even in 1972. The parish or her family could have bought it for her.

My first guitar was a Sigma 12-string, which I still have. All laminate, it cost $170 in 1978. It is of about equal quality as the GRC-7 I have.

I don't understand the belief that it could be valuable, or worth $500 - $700. No way. Guitars being made today with solid tops, selling for as low as $170, are far superior to the Sigma I have. The Blueridge guitars with solid tops/laminated sides have the same OM shape and are much more playable, sound better, and are very affordable. The BR-43 OOO-shape is $415 at Elderly Instruments. Guitar Center also has sales where solid-top Taylors can be bought for $400 (Taylor 100 Series). There are many companies making affordable, solid top instruments today--far superior to any budget imports being made before (about) the year 2000. I would never pay more than $100 for a used Sigma unless it had a solid top, but even then not much more unless it had spectacular sound and action because a new one would be minus the dings, dents, and the discoloration where Sr. Jackie's arm rested when she strummed at Mass and around the convent. I just use it to knock around with--take to the beach or whatever. It's fine for that. The action is fine, the neck is good. It sounds okay. It does not respond like solid topped instrument would.

Seagull, Blueridge, Recording King, and others make excellent guitars now. Somewhere along the line, companies learned how to mass produce better guitars, with solid tops being perhaps the greatest factor. But also, construction methods and details are just better now.

Solid top Sigmas do exist in some models and can be found, and they do improve in sound as they age, unlike laminated tops which will never sound better than the day you buy it, but very decent budget-priced guitars are now available in abundance.

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