I have come to the end of my Tone Quest for the G-DEC. I have been able to "tune" the tone of the G-DEC amp cabinet to take out a considerable amount of the "thinness" and improve mid-bass response and overall tone.

I recently tried several materials (individually and combined) in my quest to improve the G-DEC tone without having to spend big bucks or complicated modifications.

The first material, Hollofil (a poly fiber stuffing for pillows and such) worked great. It was a noticeable improvement and only cost $2.11! This represents the cheapest and easiest single mod that you can do to the G-DEC

After looking at the G-DEC amp enclosure I realized that what Fender did was spec out an 8" 8 ohm dynamic range speaker. This type of speaker is similar to what you would find in a single driver studio monitor.

I have repaired several studio monitors and most of them use some sort of "dampening" material to baffle the air flowing in and out of the speaker cab.

So I decided that it couldn't hurt to try it on my G-DEC since there are only 4 screws holding the back cover on.

I bought a 10 oz bag of Hollofil poly fiber filling. I got it at the fabric store for $2.11

I used 1/2 the bag (5 oz) and carefully stuffed the Hollofil fibers into the G-DEC enclosure being careful not to "pack" the fibers. They should be loosely stuffed into the enclosure.

Just remember not to pack it in there tight! Just loosely "push' the clumps of fiber into place. The fiber is in big enough clumps to not interfere with the speaker movement. The poly fiber needs to just baffle the air moving in and out of the ports on the amp cab.

That's it. No problem. If you don't like the different tone, just *carefully* pop off the back cover (4 screws) and remove the poly fiber filling. You can also "tune" the amp cabinet to some degree by adding more or less poly fiber. Just remember not to push so much in that the fiber is touching the speaker cone. If it touches the speaker magnet or frame it's ok.



So..... How did it work?

It worked great. I think it added some more tone to most of the amp sounds (though on "buzzy" over distortion settings it was hard to tell). The Bass from the MIDI drum hits harder and I can hear more separation from the "Amp" sounds and the MIDI sounds.

Inside the G-DEC enclosure there are 2 ports that are 1 3/4". The Hollofil material helps slow the velocity of the air on the back side of the speaker before it leaves the amp cabinet. The fibers "trap" the higher frequencies and the lower frequencies pass out the port. Works like a charm.

I A/B'd the before vs. the after. I asked my wife to listen also and she said the "stuffed" G-DEC definitely sounded better. It won't make me give up my Hot Rod Deluxe, but better is better! Right?

It was worth the $2.11 and about 2 min to install.

Hollofil is just a brand name of polyester fiber. I used it because it has "hollow" fibers that help insulate you when you use if for a jacket. Regardless of which brand of "stuffing" you use, you want the loose fiber and not the batting on a roll.





The next material I tried is a dense foam called "Sonic Barrier". I installed the sonic barrier foam by cutting it to a size just slightly larger than the required dimensions and pressure fit it in (that way I can remove it with no trace of installation). The G-DEC tone was still better than stock but not as good as when using the Hollofil. I think the reason is because it doesn't change the air velocity inside the G-DEC cabinet. So it is better to combine the materials (Hollofil and "Sonic Barrier")





The last material I tried was some Dynamat. I had a much better success with the Dynamat. This is a dense rubber material on a foil backing used for dampening of vibrations.

I finally found and installed some vent tubes for the 2 ports on the G-DEC. This changes the port length and affects the tone.





Here is my total parts list and expense:

1 bag of Hollofil Poly Fiber Stuffing $2.11

2 Plastic (1 3/8") Port Tubes (with screw flange)
cut to 2" (top port length) and 3" (bottom port length). $3.00

1 (18" x 24" @ 1/2" thick) Sonic Barrier dense foam pad (attached to the back of the amp cab panel). $7.47

3 Sheets of Dynamat (or similar) (10" x 10") acoustic byutal rubber dampening material (lined the interior of the amp cabinet). $15.90



Total (USD) $24.48


I bought these parts from different locations, but you can get them all from Parts Express in a single order (except the Hollofil, get it at a fabric store).

Parts Express Website Linky![[http://www.partsexpress.com/|]]



All these items can be easily installed in a very short amount of time. You will need 8 small screws to attach the port tubes (make sure they are very short as to not poke out the front). I used some Dynamat to seal them against the wood.

The change in the tone was considerable. It was worth every penny of the $24.48 I have spent total. That is way cheaper than buying a new speaker.



The tone sounds very good for such a small amp. The definition and separation of tones is great. The bass hits hard from the MIDI and speaker doesn't break up like it used to when the volume is up.



The Dynamat keeps the G-DEC amp cabinet from resonating. The Sonic Barrier foam pad (glued to the back removable panel) makes up for this part’s lack of thickness and prevents resonating vibrations. The plastic port tubes helps "tune" the frequencies that are passed from the back side of the amp. Lastly the Hollofil changes the velocity of the air moving though the ports and inside the amp cab.

These are cheap mods that anyone can do. They are simple and will noticeably improve the overall “Tone” of the Fender G-DEC.

I will try to post some pictures and some sort of Step-by-Step guide soon.

~Mike R~