GA-79 RV volume boost?

[Mr. Rhythm]

I love this amp but I'd like to get a bit more volume out of it. I play a Guild X170 through it and although it is a perfect amp for small combo work I was wondering if swapping out the 12AU7A for a 12AY7A or 12AX7 would give it more punch.

My Blues Jr. at 15 watts seems to have twice the loudness of the GA-79's 30 watts. However the GA-79's sound is more open and much less boxy than the Blues Jr. All it seems to need is a little boost.

 

Any recommendations would be greatly appreciated.

[Mr. Rhythm]

I appreciate the curiosity expressed by those who have browsed my post. My concern about its lack of volume punch has lessened since the original comment and question. I've learned to just dime out the volume on the amp and control the dynamics on my guitar. It works out well for my purposes.

 

I use it primarily for rhythm guitar in a jazz big band setting. The guitar I use for this is a (Westerly) Guild X170 made in 1988.

[Versatile]

Interesting post.....

 

IMX perceived volume can vary widely, particularly with EQ adjustment

 

And 'traditional' vs 'modern' amp designs

 

There is a spectrum of rhythm guitar sounds from the unamplified Freddie Green style to the syncopated 'comping' fingerstyle

 

Each requiring different approaches regarding being heard...

 

V

 

[stein]

The speaker you use has a LOT to do with how much volume it will put out. Generally, the higher power speaker it is, the more sensitive it will be. A speaker that is 89db in sensitivity will be MUCH louder in the same amp as a speaker that is 85db sensitivity. Older amps tend to have speakers more appropriate to the amp, while nearly all modern ones have high power speakers.

 

I am not sure this is all of it for you though. That amp runs off 4 el-84's right? If I remember correctly, that amp is a stereo? I think it should be two 15 watt amps (2 el-84's) into one speaker each, wHich I imagine even with the stock speakers should be at least the same in volume as the BJ.

 

I would check to make sure you are using the right settings (I think there may be a way to run it mono at 30 watts) and then see what you are using for speakers.

 

EDIT: SUPPOSING i AM RIGHT ABOUT THE AMP)

[Mr. Rhythm]

Thanks to you both for your observations and suggestions.

 

I currently plug my guitar into the center (accordion) input and set the output setting to "mono". From your comments I get the feeling I owe it to myself to get all the tubes checked for any quality issues.

 

The amp is wonderfully quiet even under harsh (heavy fluorescence) conditions.

[stein]

Good idea to find a good amp tech to be able to keep your amp in good shape. If it hasn't been serviced in years, it might be time to replace the filter capacitors (they require replacement every so many years, and when they start to dry up, usually the amp still works, but will not sound its best).

 

If a tech suggest having the tubes replaced, KEEP THE OLD TUBES! The tubes are worth something, at the least having a record of what the amp likely came with. At best, they are still fully working and sound better than what you can buy new (try looking up what a tested, NOS RCA tube will cost you). The tubes could be worth a lot of money, AND the amp is worth more if you have the original tubes.

 

When a tech chooses to recommend new tubes, the reasons may vary from putting fresh tubes to remain on the safe side (to keep the amp in good shape), or he could not have the equipment to fully test your tubes, or he could think they are questionable. In many cases, he may not know or care what exactly the value of the tubes are, or he may recommend a service SO HE CAN GET HIS HANDS ON YOUR TUBES.

 

If you are still reading, a little more about tubes: in most of the el-84 amps I have experienced, they tend to go through power tubes faster than other types. But, nearly all vintage amps will go through power tubes faster than preamp tubes. Preamp tubes about half the time seem to last a lifetime, the other half they seem to be wore out. I might tend to pull the power tubes and run cheaper ones, just to preserve the tubes.

 

If you are still reading, you might check what the speakers are to see if they are original and consider pulling them for the same reason. IF they are original, (and especially if they are Jensen) they will be VERY valuable, and add greatly to the value of the amp. They will also be very old, and just by age alone, will likely blow within the year if you play it often. Vintage jensens sound significantly better than "reissue" speakers, but they even in times they were new, had a tendency to not be able to last long in the amps they put them in at full volume. If they have survived this long, the glues used are ready to give ANY MOMENT at worst, and not able to take what they could when new at best.

[Mr. Rhythm]

Many thanks for your thoughtful comments on my issue with the GA-79. Although I wouldn't describe myself as an impulse buyer, I couldn't help buying this amp for $960. after playing through it at a used guitar shop in the Minneapolis suburbs.

 

I had tried the same model a few years ago at the Chicago Music Exchange and was taken with the quirky design of the cabinet and electronics. However their price of $2,200. dampened my enthusiasm at the time. When I saw it again I couldn't pass it up.

 

Your advice is well taken but I don't have a clue as to where to take it for a thorough check up in the Chicago area. I know many guitar technicians but not many amp techs.