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Need some info on the ROLAND GA-120

Started by camelman, December 26, 2010, 09:43:48 AM

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Is there someone who knows the Roland GA-120 guitar amplifier ?

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camelman

Happy Holidays to all,
I just bought a guitar amplifier, it is a ROLAND GA-120, which is in excellent condition. In fact, it resembles the JAZZ CHORUS 120, but with an equalizer, while the JC-120 does not. I am seeking information about this amplifier: technical specifications, user manual etc. ...
Does anyone know this amp?
I tried it yesterday and it sounds amazing! Really terrific, especially in clear and light tones.
Thank you for your help.
camelman

joecool85

#1
Have you tried contacting Roland?  That might be your best bet.

Good luck  :tu:

**edit**
I didn't see your manual here, but maybe it is listed under another model name as well? 

Check it out: http://www.rolandus.com/support/product_manuals/?group=3
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

teemuk

#2
Ha! You found one of Roland's best kept secrets.

They were introduced in about 1977, just few years after the first Jazz Series amps. There was also a daughter series, GB, for bass guitars. Basically, I think the GA's are very much like the -early- (and a strong emphasis on that detail) JC-series amps, with the exception of having the chorus replaced with a graphic EQ. So, they likely feature a crude overdrive channel, (non-user-adjustable) soft clipping limiter before the power amp, and possibly some current feedback to make the amp interact with the speaker load. All features that were stripped off from the later versions of JC-series amps (only the early versions had them).

Like the JC-series there also was a re-issued R&P version of the series featuring Roland's special R&P speaker technology. In GA-series of amps that revision also meant addition of some kind of "power compression" control, which the basic version lacked.

You might get the manual from Roland, but nevertheless they are pretty straightforward amps so you don't really -need- one: What it says in control or rear panel is what it does. The 120W in the model is the output power, GA-120 might be a stereo (60Wx60W) amp - or not.

J M Fahey

Quoteaddition of some kind of "power compression" control, which the basic version lacked.
Interesting, any info on that?

teemuk

#4
Unfortunately no.

I can only find some Japanese manuals but, since I can't read nor speak any Japanese, they don't help at all in shedding light into what this "power comp." feature was . Nevertheless, the R&P version has one potentiometer more (next to Master Vol) plus an additional footswitch jack.

Anyway, the feature is likely just a plain compressor circuit.




camelman

#5
Teemuk thank you very much for the details that you provided me. Actually I was wondering whether the 120 watt (GA-120) are in RMS on a single channel or in 2 times 60 on two channels. This amplifier has two inputs: a high and low, and I do not think I can plug into both inputs. Personally, I tried to push the amp at full power and although it sounds very strong, I do not think either of 120 watts. In this test of strength "overdrive" was not engaged.
By the way, do you have an email address where I can send my request to Roland, as I have already written the site address on "contact us" and I have not been answered yet.
Thanks again.

camelman

The two pictures shown above are the AG-60, here is the picture of the AG-120:



teemuk


J M Fahey

The *net* pages, written in HTML can be translated by Google or other services; I'm using Firefox and have an add-on which does exactly that.
Now, on .PDF files, you're on your own  :'(
PS: automatic translations can sometimes be very funny, but usually still help a lot.
My Son Alberto speaks and reads very good Japanese, but problem with ideogram based languages is that you have to know many thousands of them, and from that specific area.
He often translates for me, say, "(electric)ray + red metal + woven silkworm nest" and I understand he refers to "power transformer winding".
I just made this up but it's not too far from the truth.
Of course if he had studied *technical* japanese he would have recognized such a combination of Kanji characters at once.
Not an easy language to master.
Wish me luck, I'm starting *Chinese*.

camelman

Thanks to you J M Fahey,
I've tried .............unfortunately it does not work.
Perhaps Alberto can give us a hand ?

Good luck, by the way, for your Chinese studies ?
Good wishes and regards

camelman 

J M Fahey

Hi camelman.
really it does not say much, if at all.
It's not even a user manual but a brochure.
It tells you nothing you don't already know:
"plug the guitar here ... bass adjusts low frequencies ... the footswitch footswitches ... 120W ... 2x30cm speakers ... do not expose to rain and moisture ... " and so on, plus some cheesy 80's suggestions to get "Jazz/Country/Rock sounds".
If you really need it, these guys have a reproduction 16 page Service Manual, *much* more than just the schematic, for only U$9 + U$2 Mail.
http://www.stereomanuals.com/man/rep/roland/
*I* would definitely buy from them !!!!
Someday I will need it.