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[Frank]

Hi!

Just picked up a Yamaha G100 top and 4x12" cab. It is a much better sounding amp than I expected.

30+ years ago, my dad bought me my first amp - a brand new Yamaha G50-112 - and it served me for many years. But I never liked its sound. My guitar back then was a copy of a Gibson Melody Maker model D, with single-coil pickups, and the combination of the two was just so glassy bright and shrill. The distortion was awful too. I sold that amp when I got my first Vox valve amp, and stayed clear of Yamaha solid states for years.

Then I found this G100 in a garage sale. I checked it out, and was very surprised to find out how good it sounds! I played a lot of classic rock stuff on it with a tele, and it just kept sounding good.Nothing like my memories of the G50-112, though it is the same series of amps. The G100 distortion seems to smoothen the sound, unlike how I remember my old G50-112 distortion, which had a raspy fuzzy sound. It has much richer lows that the G50 too, but that is probably due to the 4x12 cab. (I once ran my G50 through a 4x10 cab, and that sounded a lot better). The G100 has a nice tremolo too. The reverb on this particular head is very weak. Must be some failing components, as I remember the G50 had a loud clean reverb. I wonder if there are design differences between the models in this series that can explain the difference in sound between G50 and G100? It certainly sounds better.  

I remember the G100 very well from the catalogue (that I still have), and our bass player used to play the B100 head. It is suppose to have been designed by Paul Rivera, and the ads at the time boasted valve-like frequency response. With the G100 this is almost believable. Another thumbs up to a solid state amp, and the G100 really gives these old Yamahas a bit of vindication in my book.

Frank

[teemuk]

Reminds me of a funny story that I’ve seen repeating itself a few times with different amps…

Solid state sounding??? I can see 2 tubes in the back and could smell them cookin while I was playin. The tubes have covers and I was too lazy to take them off but from the size they look like 6L6.

…

Look, SS can't POSSIBLY sound this good and be touch sensitive and have such a smooth drive. If that is so then the tube amp Gods have been lying all along and my life's quest for tone is all for nothing.

…Needless to mention, the guy who posted the quoted rants about his G100 to some forum saw two big filter caps that were sticking out of the chassis and made a mistake thinking they were tubes. If it looks like a tube amp, it sounds like a tube amp.

But shheeeessshhh, does Yamaha have a history of making EXCELLENT amps that either fly under the radar or go totally unnoticed. I mean, aside to G-series, their VR-series slayed Roland’s Jazz Chorus amps, and then they had the SR-series, which was also nothing but awesome but so rare that you can’t even find a manual for them in English language, then the DG-series, which was everything Line 6 at those times should have been, and so on.

I wonder if there are design differences between the models in this series that can explain the difference in sound between G50 and G100? It certainly sounds better.

There are. The preamp designs in series I and II are very different from another. For example, in series II they went from single-channel discrete design with simple tone control stack to creating a dual-channel (in some versions) op-amp based circuit with that parametric mid-range control. The distortion circuit was also revised from being a simple diode clipper to being a diode clipped + overdriven FET. All that made a ton of difference.

Note that the speaker configuration also made huge importance: G50-112II and G100-112II had a single-channel preamp (which was naturally revised) but G100-115II, G100-210II and G100-212II used a dual channel preamp board with individual tone controls for clean and overdriven channels.

So aside from series, there's also this aspect to judge them - not to mention they would have had speakers that sounded different too. Very important!

The series III was quite close to ser II but they made modifications to the power amp design and managed to loose some of that nice soft clipping the first versions of the design had. Likely some other changes were made too since reputedly the tone wasn't anymore that good with them... but I've never A/B'd the ver II and ver III designs in close enough detail o find all details that were changed.
Few minutes with google search should however locate complete service manuals for G50 and G100, and for all three versions I, II and III too.

[Frank]

Reminds me of a funny story that I’ve seen repeating itself a few times with different amps…

Solid state sounding??? I can see 2 tubes in the back and could smell them cookin while I was playin. The tubes have covers and I was too lazy to take them off but from the size they look like 6L6.

…

Look, SS can't POSSIBLY sound this good and be touch sensitive and have such a smooth drive. If that is so then the tube amp Gods have been lying all along and my life's quest for tone is all for nothing.

…Needless to mention, the guy who posted the quoted rants about his G100 to some forum saw two big filter caps that were sticking out of the chassis and made a mistake thinking they were tubes. If it looks like a tube amp, it sounds like a tube amp.

I found that quote on the web too. Hilarious. Reminds me of my first band. I played my G50-112, but my buddy played a big Vox amp. It sounded so much better than mine. I looked for a long time inside it, to spot the valves, but there was nothing glowing in there. Turns out his amp was a Vox Dynamic Bass solid state amp! The british Vox ss amps of the late 60'ies just sound better.

I wonder if there are design differences between the models in this series that can explain the difference in sound between G50 and G100? It certainly sounds better.

There are. The preamp designs in series I and II are very different from another.

Yeah, but both my old G50 and this G100 are series I, single channel amps in black and silver. I remember just one or two years later, Yamaha started using a brown design, and two channels, but I never played any of those.

Few minutes with google search should however locate complete service manuals for G50 and G100, and for all three versions I, II and III too.

I already found the G100 service manual. I'll try and track down the G50 and compare.

Frank

[teemuk]

Yeah, but both my old G50 and this G100 are series I, single channel amps in black and silver.

Likely just a difference of higher headroom and different speaker then.

[Moby]

I had a yamaha 2x12 combo many years ago.  I forget the model but it was (something)100.  It had a parametric EQ that I loved.  Does the G100 have a parametric EQ?

I had to give give up the amp.  I borrowed a friends PA monitors and they got stolen and I didn't have a dime to cover it so I gave him the amp.

[Frank]

I had a yamaha 2x12 combo many years ago.  I forget the model but it was (something)100.  It had a parametric EQ that I loved.  Does the G100 have a parametric EQ?

Yes and no. It depends on which series G100 we talk about.

I have learned this much, that the Yamahas came in three generations, commonly called series I, II and III respectively. The series I amps were black with white lettering and silver on the knobs. They were single channel amps. This is the G100 head that I have. My memory is that these amps came on the market around 1978. I know I have the original colour brochure for this series somewhere, but I couldn't find it.

Series II came with a brownish colour grill and panel and were two channel amps. These amps came pretty soon after the series I. My memory dates it somewhere around 1980-81. I remember both these amp series from back then, as I had a series I G50-112.

I know nothing about the series III, except that it exists. (I had lost interest in Yamaha amps at that time).

The series I amps did not have parametric EQ. There were simple bass, middle, treble and bright tone controls. Internally these amps were made with discrete transistors. The distortion was a classic two diode clipping design, much like those found in old fuzz pedals.

The series II i believe came with the EQ, but were made with op-amps. They are another design.

One of the series is said to have been designed by Paul Rivera, who also designed amps for Fender. But I can not find any conclusive answer on the web to whether it was the series I or II that he designed. I suspect it was probably the series one, with the descrete transistors.

[teemuk]

G100-212 (not called Series I back then)
These actually came in two different striped tolex colours, black and brownish


G100-212 II
These again appeared in two different striped tolex colours, same as the early one, but new features were a revised preamp with eg. parametric mid control, and in many models a dual channel setup. Even the single channel amps, G50-112II and G100-112II, still did have a revised preamp circuit. A crude short circuit proetection was also added to power amp.


Note that around the time that G-series (both I and II were introduced) there were also parallel series labelled "J", "F", and "B". B was a series for bass amplifiers but the F and J series are actually very close to G-series amps. F-series amps I've seen include the parametric mid control.


G100-212III - GII Series
This was what Yamaha labelled as the successor to G-series, the GII-series. Totally revised look no longer using the old Yamaha striped grille and with coloured knobs. The preamp design is very similar to G-series II, but as far as I know, now all models came in dual channel configuration. Power amp circuit was modified quite extensively. These amplifiers were also manufactured in USA.

[Moby]

Hi Teemuk,  That was my amp!  The G100 212 II with parametric EQ!  I used to plug my guitar into a pan pedal and run the pan pedal into the yamaha and a peavey heritage.  With the pan pedal in the middle and using both amps it was an awesome layered tone.

Cheers

[RichardM]

G100-212 (not called Series I back then)
These actually came in two different striped tolex colours, black and brownish


G100-212 II
These again appeared in two different striped tolex colours, same as the early one, but new features were a revised preamp with eg. parametric mid control, and in many models a dual channel setup. Even the single channel amps, G50-112II and G100-112II, still did have a revised preamp circuit. A crude short circuit proetection was also added to power amp.


Note that around the time that G-series (both I and II were introduced) there were also parallel series labelled "J", "F", and "B". B was a series for bass amplifiers but the F and J series are actually very close to G-series amps. F-series amps I've seen include the parametric mid control.


G100-212III - GII Series
This was what Yamaha labelled as the successor to G-series, the GII-series. Totally revised look no longer using the old Yamaha striped grille and with coloured knobs. The preamp design is very similar to G-series II, but as far as I know, now all models came in dual channel configuration. Power amp circuit was modified quite extensively. These amplifiers were also manufactured in USA.

First post here, sorry to drag up an old thread, but where does my model, G100B-212, fit in?

Is it like a series 1.5?

Some pics.











 
 

[probodger]

I guess you saw the other G100 thread? It's a Japanses market only version of the G100 - read it online when I got mine, but can't for the life of me find the page with the info on again.

[RichardM]

I guess you saw the other G100 thread? It's a Japanses market only version of the G100 - read it online when I got mine, but can't for the life of me find the page with the info on again.

Thanks for that. 

Though, in Australia this model is quite common, perhaps the 240 power saw some imported to here. 

 

[probodger]

CAn't remeber what the power switching on the rear of mine is, but its something like 110/210/230volts I think.

Another mystery to me is why does mine have a different style knob to any other G100 212 II I've seen, I guess it's possible somone may ahve changed them in the past.

[probodger]

I also need some castors/wheels for mine.
Any ideas where I can get some from?

[J M Fahey]

Well, to Australians Japan is not "the Far East" but the "very close North".

As far as wheels, forget originals 30+ years later, but you can buy good general purpose ones at a hardware store and fit them.

[probodger]

Ok better way of posing the question would be, what size are the cators for anyone who has a G100? As they are the pop-out type, so if I can get some that will retrofit then life will be easy.
I don't really fancy redrilling the old box unless I have too.