Fender Rumble 15 Mod

I've had a Fender Rumble 15 for about four years and I was getting very tired of the sound. I use it strictly for practice.

I tried to get rid of it... posted it for as low as $25 on Craigslist and didn't sell. GC wouldn't give me even a lollypop for it.

Then. I stumbled onto some threads by people buying Ampeg BA-108's and replacing the speaker with the Eminence Alpha 8a, which sells new for $49.99.

So I could buy the Ampeg BA-108 used (about $60 if you can find it), or new ($100), and then replace the speaker (another $50).

So, I ordered the Eminence and put it in the Rumble.



Then I said, what the heck, I'm going to port the little thing and see what happens. So I ordered one of those flared 2" port kits from precision.

After doing some calculations, I "thought" I was shooting for 45Hz... but I measured wrong... and after cutting the hole on the side I found out that the inside flare would not fit because it bumps into the speaker.

So I had to extend the tube... right now it's about 11.5"... I forgot, so it's tuned to around 35Hz, if my calculations where right. (I estimated the volume of the enclosure at .574 ft^3.)

I also lined some of the sides of the speaker with AC filter foam (I had some and it was a last minute decision). And if it matters, the foam is black.

Ok, I put everything back together. Here's how it looks like now.



Results? Less distortion. More clarity. The notes on the B string on my 5er sound better. Overall I'd say it sounds better.

Before I just hated the sound going straight into the amp so I always ran a BDDI in front of it. Now I just plug straight into the amp.

I's say the mod was a success. Was it worth it? Well, that's subjective. But I did learn a thing or two in the process so that was definitely a plus.

 

Thx Astro and Thunda for your comments.

I initially thought of tuning to 50. Per your (Astro's) analysis the B string would have benefitted more from that 2nd harmonic boost. But it's pretty good as it is... And I suspect primarily because the Eminence is so much superior than the stock speaker in every way. Considering that this is a practice amp I'm going to leave well enough alone, that is, until the time I feel the itch to tinker with it again. Right now I'm set.

Vanilla, some people are buying Ampeg BA108's and replacing the speaker with the Eminence. I found a thread where someone put a 10" speaker in the BA108. If I was starting from scratch, I'd probably go the Ampeg route, but since I already had the Fender and I couldn't get rid of it I was willing to bear the risk of thrashing the amp. But it turned out nice and I think it would do fine in an acoustic setting.

I would do it again if I found a Rumble pretty cheap... Perhaps someone even has one that is not using it and would be willing to give it away.