Gibson G30 amp

[BluesRider]

Hi everyone,new here,and new to amps. I have some really simple questions that I'm sure everyone will laugh at,but I'm used to being laughed at,so here goes......

I've got an old Gibson G30 amp that I've had about 25 years.I think it's quite a bit older than that,but I don't know for sure.I played it a few times back in the day(with a borrowed guitar),but it's been stored rough ever since.It seems to be in fairly decent shape,except most of the knobs are missing.

I know squat about amps,I've always played accoustic(Poorly.I've been a beginner for 35 years  ).Soooo....I need some help with what all these controls,and so forth,actually do.

I should mention here that I have my very first ever electric guitar on order,a gold top Les Paul wannabe,but I haven't got it yet,so I haven't had a chance to experiment.

First,I guess,where can I get replacement knobs? I see Fender ones all over Ebay,but no Gibson ones.Will Fender knobs fit?

Second,there are two inputs on the front,"low" and "high" What does that mean?

Third,there's an input on the back for a foot switch.What in blazes can I switch with it?

Fourth(and I don't have the amp here,so I'm doing this by memory),there are a couple of tone and volume pots,plus a reverb pot,and these are self explanatory,but there are a couple of others over toward the right,one says "speed". I can't remember what the other says.What do these things do? Is it tremolo?

Thanks for your patience with a rank beginner.And,thanks in advance for any help/advise you can give me.

Err....Except,maybe,chuck it all,and buy a Twin Reverb.That'll have to wait until I relearn that pentatonic scale again.Let's see...That's the fifth fret on the third string....No,wait..Ahh....  

Cheers!
BR

[askwho69]

I think most of knobs are standard size so it will fit even cheap knobs at local store.

about the other question about low and high try them both what fit most to your ear

hope this will help

A2

[BluesRider]

Well,it sure won't hurt! Thanks for the info on the knobs.

[joecool85]

If you want to order knobs, smallbearelec.com has a good selection.  The big thing to check for is whether the pot shaft is round, knurled (toothy) or D shaped and then get the appropriate pot from there.

[LJN]

the spped knob is either for trenolo or vibrato. the other knob should say intensity or strength. That's a very hard to find amplifier. so it will be very hard to locate knobs that look anything like the original ones. the footswitch is for the reverb and tremolo, to turn them off and on. that way you can use them as if they were effect pedals. my advice to you about the knobs is to find some you like and put them on it. hang on to that amp, you'll probably never find another one like it. I know how frustrating it is to try to find out about an old amp that keeps bringing you to a dead end with your research. I've had the same problem trying to find out about my amp. But, I've realised, if it works, and you like the way it sounds, that's plenty good enough. you can find out all you need to know about it just by simply plugging your guitar in and playing some of your favorite tunes, also by turning all those knobs one way or the other. They're right about smallbear. I ordred some parts for my amp from them not too long ago. they're a little slow on shipping, but they're a great company to order from. I hope this helps you, and that the amp brings you many years of enjoyment.

[awbass]

Hey all. I just got a G 20 today (a friend gave it to me for helping him move), and it's got some issues.  It has what I'm pretty sure is a blown Radio Shack speaker in it, and the trem effect doesn't seem to work.

What speaker should I get to replace the blown one, (and how much do they cost) and is the trem not working because the pot is bad?  (It sort of worked for a bit, but now it doesn't seem to do anything).

Also, whoever put in the Radio shack speaker, screwed it in through the front mesh/grill 

Any info would be greatly appreciated-the webernet has very little info on this amp.

Cheers.

[J M Fahey]

Get a Jensen MOD speaker , of the same size.
They sound very good and are inexpensive.

[joecool85]

Get a Jensen MOD speaker , of the same size.
They sound very good and are inexpensive.

Agreed.  Musiciansfriend.com has them cheap.

[awbass]

Thanks!  I know it was free, but will this amp be worth having the speaker and other electronic issues addressed?  Apparently, there is only one person in this region of the country (DC area) who will even look at a solid state amp.

Also, how do I figure out the right type of speaker.  The back says "120 VAC 50/60 HZ 30 Watts"

Finally...how do i get a footswitch for it...?\


don't mean to be a complete noobie, but I've just had my head in acoustic instrument land for years.

thanks again!

[joecool85]

One question at a time.

Yes, I think it's worth fixing.

It will take a 12" speaker with an 8ohm rating.  I was thinking with only 30w it would take an 8 or 10 which is why I agreed on the Jensen Mod series speakers.  Since it takes a 12, something like this: http://www.musiciansfriend.com/accessories/weber-speakers-signature-series-ceramic-12s-25-watt-12-speaker/660020000612000 would be good for a cheap option ($35).  

OR something like this: http://www.musiciansfriend.com/accessories/eminence-legend-1258-75w-guitar-speaker/667702000000000 if you don't mind paying $70 and you want your amp to sound AWESOME.

As for the footswitch, it looks like it controls just the tremolo and you could get any single button foot switch for it and plug it in.  Or you could build one.  It just shorts tip to ring when clicked off.

Here is the schematic for your amp: http://www.gibson.com/Files/schematics/G10,G20,G30.pdf

[awbass]

Awesome.  Thanks for the wisdom!  I'll post again once i've made some improvements to let you all know how it worked out.

[awbass]

Just updating-after a good long while!  This has been on the back burner for many reasons (children being the main one).  Last night, I pulled this amp out again, and have some more forensics to report.  It appears that when they replaced the original speaker with the radioshack thing, they went with a bigger speaker, which obviously wouldn't slide into the hole from the front.  So, they put it in through the back, and bolted it in through the front, mesh and all.  Oh, and they took a hacksaw to the original speaker mounting bolts.

So, it looks like it took an 8 in speaker?  Do you measure the speaker diameter from the size of the hole, or from the distance between opposite bolts?  I want to order the right thing since I apparently only work on this thing every two years.

Also, since I'm going to have to take the mesh off to get the original mounting bolt  fragments out, should I just replace the mesh completely when I'm done?  I'm assuming there are other threads about that.

As always, thanks for the wisdom.

[Roly]

Just to clarify, that "30 Watts" is power input, the power output (to the speaker) will be about half that, still plenty loud.

Speakers are measured by the diameter of the cone, 8, 10, 12, 15 etc., but however you measure it you should get closer to one of these diameters than the others.

Look forward to hearing back from you in a couple of years.   :lmao:

[J M Fahey]

The speaker size will be close to opposite bolt distance +1/2" or wood panel hole diameter +1" .
Accurate enough, because you only need to decide whether it's closest to 8" , 10" , or 12".