JBL 15" Speaker

Jim Gaines · Post by **Jim Gaines** » 8 Apr 2010 4:18 pm

Gentlemen, and Ladies,

I have a Model number "M31-4" JBL 15" speaker that was taken out of and old SG Gibson amp that was made in the 70's. Believe it or not it is a 4 ohm speaker.

Has anyone ever heard of this model speaker, and have an opinion on it? Also would anyone know of a good repair shop to recone it if it would be needed?

I thought I might use it with a Twin (external jack)along with the 2 JBL 12's to add just a little more bottom end.

Thanks for your time,

Jim Gaines

Jerry Overstreet · Post by **Jerry Overstreet** » 8 Apr 2010 5:36 pm

I had an M 30 in an old Sho-Bud Amp. I think that one and the M 31 are very similar if not the same as the D130. Mine sounded great, but wouldn't handle a lot of power. It was 8 ohm and had a grey frame and alum dust cap. 4, 8 16 ohm coils all were common in JBL's.

Yours should sound nice. Woody Woodell, Nashville has a great reputation for doing fine repair work on the old JBL's.

John Jeffries · Post by **John Jeffries** » 9 Apr 2010 6:52 am

I have two Sho-Bud "Christmas Tree" steel amps.....one has a 15" JBL D-130F 8 ohm speaker and the other one (mid to late 60's vintage?) has a 15" JBL M31 8 ohm speaker. Both amps work great & sound very similar....the M31 speaker seems to be just a tad "warmer" sounding to my ear. I know that JBL speakers were used in the old "Kustom" amps (60"s & 70"s), perhaps the M31, but I'm not sure. I think that the Baldwin Co. owned Kustom for a time back then, and maybe also owned Sho-Bud during that period as well....hence a possible connection.

Dave Grafe · Post by **Dave Grafe** » 9 Apr 2010 7:12 am

Is the Twin wired to accept a 4-ohm extension speaker? I'm no expert on Twin Reverbs but you want to be very careful about impedance matching with a tube amp, it's even more critical than with a SS amp.

Perhaps one of our Fender gurus will chime in here with more detailed information...

Jim Gaines · Post by **Jim Gaines** » 10 Apr 2010 8:38 am

Thanks to all who responded and hope others will as well.

Thanks again,

Jim Gaines

Larry Moore · Post by **Larry Moore** » 12 Apr 2010 9:52 am

Hello John, or Jerry can you help me to get a year date on my Christmas Tree amp S/N 1068???
I'm gussing because the S/N# is stamped on the back side of the chassie It might mean Oct.of 68.
What do you think?
It also has the M-31 8ohm 15" JBL.
Also how would a 15" BW do as a replacement?
Thanks
Larry

John Jeffries · Post by **John Jeffries** » 12 Apr 2010 1:32 pm

The numbers stamped on my two Sho-Bud amps are "0649" and "1172". I'm not aware that these numbers are significant in regards to a particular month/year of manufacture. I was given to believe that the amp stamped with the number "1172" was of "mid-60's" vintage, but I have no way of knowing for sure. If anyone knows of a contact or resource through which the year of manufacture could be ascertained through these numbers, I would certainly be interested.
I have not considered changing the stock speakers in these amps, as I am pretty happy with the sound.
Cheers, John J.

Larry Moore · Post by **Larry Moore** » 12 Apr 2010 1:40 pm

Thanks John
I am not going to change the JBL out unless something go bad. After the work Ken Fox did on mine it is like a different amp, lots of more power. I have been playing a Derby thru it, but the Emmons LeGrande II sounds good in it too.
Larry

Jerry Overstreet · Post by **Jerry Overstreet** » 12 Apr 2010 2:31 pm

Sorry Larry, I know nothing about dating these amps.

As to the speaker swap, If necessary, I would think a Black Widow would work just fine. Should be no problem. Just try to replace with one of the same impedance. [4, 8 ohm, etc.]

I'd hang on to that Lansing though if I were you.

Mike Flick · Post by **Mike Flick** » 12 Apr 2010 2:35 pm

My '74 session 400 has an M31 4 ohm in it and I'm reasonably sure it's the original speaker. If you search the old forums' electronics section for jbl m31 you'll find some interesting info.

Jim Underdown · Post by **Jim Underdown** » 12 Apr 2010 2:57 pm

I believe that the Kustom Sidewinder 100 amp had a 15ins JBL as I owned one back in 1972. Sold it when I moved to Spain but it was a great Amp. I know it was grey in colour and most Kustoms at that time were 4 ohm output. Hope this helps some
Jim from Spain

Dan Murphy · Post by **Dan Murphy** » 13 Apr 2010 7:45 pm

I was told the M-31 is the code JBL used back in the day for the Peavey speaker aplication. I too have one , and it cane from an old peavey amp.