# '62 -ish Gibsom GA-8, 16 ohm speaker, question



## bolero (Oct 11, 2006)

hey, I have one of those cool old Gibson GA-8 amps, replaced the stock speaker with a great sounding alnico Bell & Howell but it's 16 ohms

I usually only play the amp cranked, it's a little 2xEL84 powerhouse....but I'm more concerned with the 16 ohm speaker load on the amp, think this'll be ok, longterm?



thx!!


----------



## bolero (Oct 11, 2006)

pics:

ps does anyone know how the "monitor" and "echo speaker" jacks are wired up on these things?



I'm guessing echo speaker is for an external speaker, monitor is a line out?


----------



## bolero (Oct 11, 2006)

bump....

has anyone ever used the monitor jack on these?


thx!


----------



## WCGill (Mar 27, 2009)

My gigging amp was a GA-14RVT, I love that amp! Of course I messed with it a bit. Tube amps are usually forgiving of a 100% mismatch, although I'd prefer to see a 4 ohm speaker in there instead of 16. You pays your money, you takes your chances. 
Bill


----------



## nonreverb (Sep 19, 2006)

I would suggest against the 16 ohm speaker. That amp has a small output transformer and may not handle the mismatch so well.


----------



## WCGill (Mar 27, 2009)

Small?!? I can't imagine how small as my 14 had one of the smallest opt's I ever saw in a guitar amp. I replaced it with a Hammond (proprietary) 6.6k, and put 5881's in the amp. I'm surprised that they didn't cook the also-very-small power transformer, but I gigged non-stop for 5 years with that baby. I also found if you ran a clean boost into the front end it sounded even better. My harp player also liked it for harp-double the fun! And, the lousy Jensen C12R was the best-sounding speaker in the amp too. I tried many.


----------



## nonreverb (Sep 19, 2006)

I thought we were talkin' output impedance here...I his case with a stock, old and probably close to max rated transformer, there's a chance that the impedance mismatch may lead to a quiet conclusion...I've seen it before and I'm sure I'll see it again....


----------



## madkatb (May 14, 2009)

*Gibson Discoverer*

Searched for a schematic for this and came up with the Epiphone version, EA 35T, the Devon. It shows the "Echo" speaker as a speaker extension jack and the "Monitor" as a preamp out after the first preamp and the EQ (or as an "in" after the EQ- low gain?). Shows a 8 ohm speaker but if you had another 16 ohm cab in to the "Echo" you'd be at 8 ohms.
BTW your Bell&Howell speaker is a Jensen, probably 1962.
If you're really worried about the impedance mismatch, get a 10W, 15 ohm resistor and parallel it across your speaker.


----------



## WCGill (Mar 27, 2009)

[QUOTE
If you're really worried about the impedance mismatch, get a 10W, 15 ohm resistor and parallel it across your speaker.[/QUOTE]

I think not.


----------



## nonreverb (Sep 19, 2006)

A twin would handle or any number of other high powered amps with robust trannies it but when you get into old and budget amps there's always the risk. Sure, it may never happen but giving advice to that end and it DOES happen...people get cranky. I guess I'm just one of those fraidy cats who plays it REALLY safe!


----------



## bolero (Oct 11, 2006)

hey thx for the input guys....I have a spare 16ohm speaker here, what I may do is just run that as an external & it'll balance out


the original speaker was 8 ohms so I assumed a 4 or 16ohm mismatch would be ok...but 2 or 32 would not


but, better safe than sorry!!




also do you have a link for that schematic?


thanks again!!


----------



## madkatb (May 14, 2009)

*Epiphone Devon*

Schematic is at:
http://schematicheaven.com/gibsonamps/ea_35t-devon-trem.pdf

I think this must be the same as yours as it shows the monitor and echo jacks.


----------

