Gibson GA25RVT 210 Combo

The serial number for my amp is 727875. It is often referred to as a late version GA-25RVT Hawk. It has a different tube lineup and totally different feel from it's earlier version Hawk which uses 6V6 output tubes and a tube rectifier. This amp has lush reverb and a tremelo to die for. But it also has the punch of a solid state rectifier and the unique sound of the 7591 output tubes.
It has two channels with reverb/tremelo available only on channel 2. There are no extra frills here. I bought two of these amps to experiment and discover the mysteries of the Crestline early/late changes. Needless to say, I find them both fascinating.

I use single-coils and humbuckers to test this amp. It sounds a bit thin with singles but I attribute this to the dreaded Sprague network which shows up on the schematic and unfortunately affects the amp. It can be removed/altered to remove the shrills. It has the deep response of a larger tube amp but can make good use of the expanded tone controls to adjust treble and bass response. It is not noisy and can be quite loud in my music room studio. The voltage on the output tubes is quite high and it responds to volume surges very quickly with no sag or hesitation.

I bought this amp as a restoration project and had to replace all the electrolytics and cathode bypass caps. Doing so gave me peace of mind and boosted the volume considerably.
I don't know if it has the volume to gig with. It is not a thrash rock amp.

The Gibson company attempts to provide schematics for their amps but this one was a real pain to find. After searching online for weeks and hitting every forum I finally gave up and bought one from an online service. It cost me $15 but I finally had a definitive copy of the guts of this amp. The amp was made in the 60's and service will be where you find a competent tech(don't get me started). This amp has the interstage transformer of the later White Panel amp family and utilizes a light dependent resistor for the tremelo circuit. You need to archive an applicable schematic.

I have been playing at playing since I was 12 years old. I am now 55. If this amp was lost (how?) or stolen I would seek another. I borrowed one from an older gent when I was in my twenties and I absolutely loved it! Fender has the clean twang corner and those amps go for a king's ransom. Gibson amps are overlooked and that's just fine with me. They are different but not necessarily weaker sisters. They are point to point and the components are readily available to repair them. Comparing and repairing the two Hawk amps is like attending an amp school. What a hoot!

Vintage Gibson amps are notoriously ambiguous when it comes to dating, but I believe this is a '65 because it uses the 7591 power tubes rather than the 6V6s.

I got hooked on the old Gibson sound after buying a '63 Gibson GA-5 Crestline. I walked into a music store and lo, there was a near mint GA-25RVT Hawk sitting there. My gears started grinding and after about an hour of tossing it around, I offered to trade my '65 Twin Reverb -REISSUE- for the Hawk plus a flying V case from the $14k mid-90s Gibson reissues. The shop owner agreed and off I went. I want no flack from this: hundreds of thousands of Twin Reissues were made, 1700 or so GA-25RVTs were made in '65.

The amp has two channels: clean and reverb. Both channels have a dual inputs labeled "Guitar" and "Accordion." Both channels also have Treble and Bass control. The second channel has Reverb using a dual spring tank similar to a Twin Reverb. The second channel also has Tremelo, but I am currently having the amp serviced to get this portion working, so I can't comment on the depth and quality of this feature. There is also a Monitor output jack which I have only briefly used to make certain that it worked. The power switch is labeled Off - On - On. While it seems funny that an amp can be even more "On," or as we like to say, "Onner," this really has to do with the fact that it has a two prong plug. This setting switches the polarity of the prongs in case you plugged it in backwards. Yes, this does matter and -does- change the sound of the amp.

With regards to what this amp is missing, I can say very little. I knew what I was getting when I bought this. When compared to a Twin Reverb, it has all the same characteristics physically minus the midrange tone knob. I don't wish for this because I most often play a G&L Asat with Fullerton P-90 style pickups. This guitar's range in tone is very versatile, despite its "telecaster" shape. I want for nothing in this amp, and if anything I am a happier man because I no longer have to lug the 80 pound monster to shows.

I use this amp everywhere I play my guitars. Home, shows, practice. Depending on what I want to do, I either play this alone or split the signal and play through my two GA-5 Crestlines Skylarks. The amp has 25 watts of output and breaks up around 6 or so. I typically use an Electro-Harmonix Line Power Boost to increase the signal strength and help get that overdriven sound of well cooked tubes.

The amp has two ten inch Jensen speakers with paper cones. As the other review says, these speakers are quite solid for being 41 years old. I am surprised they survive the harshness of my fuzz pedal. I do expect that I will have to recone these eventually, but for the time, I will use them until they are shredded. As stated before, the amp is tube driven. It has a 12AU7 phase inverter, two 7591 power tubes and for reverb and tremelo it has two more each of the 12AU7s and 6EU7s.

This amp sounds only like a vintage Gibson amp can sound. I have a sickness and its cured by Crestline Gibson amplifiers. The volume of this amp changes drastically when rotating the volume pot. It sounds beautifully clean up until 4ish then starts to break up like a bad girlfriend. Still, unless I boost the signal, the amp sounds like a mildly dirty overdrive. Absolutely perfect for blues and rock. There is a reason B.B. King swears by Gibson amps...

I play in a rock back with similar style to Pixies, Ween, Weezer, or various other things you want to compare us to. (I hate that previous sentence, but I need to give some sort of musical reference point, I guess.)

The amp sounds good from the time you turn it on, but after about an hour of play, it has such a sweet, rich and raw sound that very little compares in my humble opinion.

I am fairly certain that this amp is in good enough condition to be relied upon for gigs and whatnot. My Fenders always seemed to break down at the wrong times, usually for various reasons not in my control.

This amp is currently getting maintenance done: recapped and tremolo repair. Perhaps I will recomment about this in a year or so, but I am going to say I hope for the best and expect good things, but won't be burned if it gets shady.

Please. Its 41 years old.

I've been playing about 15 years or so. I play mostly through Tele style guitars, my main guitar being an Asat. I also have a Fender Mexican Tele from '94 and a '58 Flying V reissue.

My other amps are also Gibsons, a '63 and '64 GA-5 Skylark. They are very simple, volume/on amps with a huge sound for 5 watt amps.

If this amp were stolen, I'd be heartbroken. I love it very much. I traded my Twin Reverb Reissue which I paid about 1100 for, but the TRRI needed work on the tremelo channel and had been in use for about 4 years. In return for the trade, I also received a case for a Flying V which when it was being sold by Gibson was priced at 500 dollars. In the end, I think I got a very good trade: common for rare and vintage.

If you run across one of these Hawks in either the 6V6 or my 7591 variety, play it. You'll be very happy, I guarantee.

This GA25-RVT '64 version is with the more powerful 2 x 7591 output unit that has practically the same schematics as the GA35-RVT with excactly the same power and output transformers. The power tubes are transformer driven. The older (and less powerful) version had 2 x 6V6 ouput tubes that were directly driven by an inverter tube. This later version has also more versatile tone controls, the input, tone, reverb and tremolo configurations are similar to those of, for example, Fender Vibrolux Reverb.
The speakers are 2 x 10" CTS with ceramic magnets and they are connected in series giving a load impedance of 16 ohms for the amp. These old CTS units seem to have a very durable cone paper, maybe because they were made out of pressed sheet paper rather than using wet molded pulp mass that tends to deteriorate with time more easily.
I measured the amp output to give 24.5 Watts RMS at clipping limit into a 16 ohm resistive load, which is a good value for a nominally 25 Watt specification. I guess one could easily pull some more power out into an 8 ohm load like Gibson made with the componentwise almost identical GA35-RVT.
The reverb tank is a Gibbs two-string unit basically the same as used in most Fenders, though the coil impedancies differ somewhat.
The tremolo has been made using an optoresistor (like in Fenders) and has a depth and intensity control.
The cabinet dimensions seem to match a '69 Twin pretty closely.

I used a '67 Gretsch Tennessean, a single coil miked Tele, a Strat and a Les Paul to evaluate the sound quality. What can I say - the overdrive was gradual, smooth and rough - all at the same time. It never became piercingly metallic, chords sounded warm and very harmonic. All of the used guitars came through with their own characteristic tone, the amp never masked this. The speakers have a great deal to do with it as they seem to break up quite early with power.
I compared the GA25-RVT to a mint '69 Fender Twin with 2 x 12" Oxford speakers and found out that the Twin was cleaner and had more "twang" and power but was more difficult to use at the overdrive range while the Gibson was there all the time.
But everybody that tried the Gibson I saw a wide smile coming on their faces after a few bars of playing.

Many vintage amps suffer from hacks and poor service carried out by unprofessional amateurs. This is the main single cause for poor reliability.
This unit has been running for almost 40 years now with a couple of new tubes and caps and still with the original CTS speakers which have survived ashtonishigly well. No severe service damage had been done to the amp. Maybe it'll just keep on cranking...

I recently bought another one of the kind. For blues and rock&roll I can't think of a better combo but for country&western it will not quite deliver enough clean power. This is definitely not an amp for somebody who's not familiar with vintage sounds and doesn't know how to live with it.