Hi all! A very nice person has given me his (deceased) father's bass amp. It's a Fender Rumble 100 v3. It works fine. However, I have read some suggested ways to improve the original Rumble, to increase clarity & clean headroom. I don't know if they apply to the V3, which (by contrast) has one speaker and no porting. So this might all be moot. The particular mods I'm considering are:
1) sealing all around the internal baffle with plumber's putty. Why plumber's putty? Seems messier than caulk or construction adhesive. FWIW: I haven't pulled the speaker or chassis, so I don't know if such a baffle is in there.
2) Seal the speaker frame to the mounting hole with plumber's putty. Doesn't all this airtight sealing prevent the cone from moving freely? The original Rumble apparently was ported, mine is not. And what if I later wish to replace the speaker after it's glued to the box? See #5 below.
3) line the speaker cavity with fiberglass insulation. I have some Corning 2" thick acoustic fiberglass batting. How does one adhere this to a cab interior? I've only previously used this insulation for studio wall/ceiling panels, where I wrapped muslin around the fiberglass and stapled the fabric to plywood.
4) replace electrolytic caps. The amp is about 10 years old, but still working. Why not wait until the caps blow?
5) replace the stock speaker. I'd rather try free/cheap improvements first. Or should this be the first thing to do?
Do 1-3 apply if the cab isn't ported? Any suggestions on a 12" speaker?
Thanks!
1) sealing all around the internal baffle with plumber's putty. Why plumber's putty? Seems messier than caulk or construction adhesive. FWIW: I haven't pulled the speaker or chassis, so I don't know if such a baffle is in there.
2) Seal the speaker frame to the mounting hole with plumber's putty. Doesn't all this airtight sealing prevent the cone from moving freely? The original Rumble apparently was ported, mine is not. And what if I later wish to replace the speaker after it's glued to the box? See #5 below.
3) line the speaker cavity with fiberglass insulation. I have some Corning 2" thick acoustic fiberglass batting. How does one adhere this to a cab interior? I've only previously used this insulation for studio wall/ceiling panels, where I wrapped muslin around the fiberglass and stapled the fabric to plywood.
4) replace electrolytic caps. The amp is about 10 years old, but still working. Why not wait until the caps blow?
5) replace the stock speaker. I'd rather try free/cheap improvements first. Or should this be the first thing to do?
Do 1-3 apply if the cab isn't ported? Any suggestions on a 12" speaker?
Thanks!
Just my 2 cents. Your approaching this musical Amp as if it were a hifi speaker app. I would look at original design on web and make sure that is correct first. Guitar amps are not meant to be "flat" but be colored by tone
Plug it in and play. How does it sound for the music you play? Is it loud enough for your band?
Best ways to decide if it is worth keeping.
Best ways to decide if it is worth keeping.
That's all great advice, thanks.
Definitely keeping the amp. But, I can't resist tinkering with gear. That's why I'm here.
I'd appreciate it if anyone can direct me to info about how/why bass guitar speaker cabs/combos differ from those for electric guitar.
Definitely keeping the amp. But, I can't resist tinkering with gear. That's why I'm here.
I'd appreciate it if anyone can direct me to info about how/why bass guitar speaker cabs/combos differ from those for electric guitar.
Open back/open baffle is more guitar cab style. Its a long time trend from 30s and 40s when early guitar speakers where
just typical underhung High Qts speakers from console radios. Not much has changed they are still usually underhung and have light cones
for high spl or sensitivity which trades off for very high distortion.
Bass guitar extends lower. So for controlled cone movement and lower frequencies expect typical sealed and ported.
And more modern type overhung speakers from the pro sound or live audio selections. With larger voice coils for power
and more heavy reinforced cones for low frequency and lower distortion from having to go lower in frequency.
Assuming the fender cab is small, youd be looking for a live sound driver with low Qts around .3 to work in a small box.
Improvement would be if sensitivity was higher to be " louder" or if linear distortion at 70% BL was higher AKA more Xmax / Cone travel.
We have no idea what the factory speaker specs are so no idea if another model would be better or worse.
Fiberglass is horrible to handle and breath. Use normal poly batten to line it. Its mainly effective at midrange frequencies where it can calm down
spikes in the frequency response from cabinet reflections. Dont expect miracles other than knowing it is there.
Long as the cabinet doesn't rattle the extra time to seal it is not useful, these are usually M roll treated cloth edge speakers and any leakage
will be the speaker cone / surround itself.
just typical underhung High Qts speakers from console radios. Not much has changed they are still usually underhung and have light cones
for high spl or sensitivity which trades off for very high distortion.
Bass guitar extends lower. So for controlled cone movement and lower frequencies expect typical sealed and ported.
And more modern type overhung speakers from the pro sound or live audio selections. With larger voice coils for power
and more heavy reinforced cones for low frequency and lower distortion from having to go lower in frequency.
Assuming the fender cab is small, youd be looking for a live sound driver with low Qts around .3 to work in a small box.
Improvement would be if sensitivity was higher to be " louder" or if linear distortion at 70% BL was higher AKA more Xmax / Cone travel.
We have no idea what the factory speaker specs are so no idea if another model would be better or worse.
Fiberglass is horrible to handle and breath. Use normal poly batten to line it. Its mainly effective at midrange frequencies where it can calm down
spikes in the frequency response from cabinet reflections. Dont expect miracles other than knowing it is there.
Long as the cabinet doesn't rattle the extra time to seal it is not useful, these are usually M roll treated cloth edge speakers and any leakage
will be the speaker cone / surround itself.
Hi - from what I find, V3 is not like the original V1 when images are viewed online. V3 is sealed, V1 ported as you noted. My view is that attempting mods based on V1 discussion is not advised.
Do you have a specific deficiency (use case) you are trying to address with the amp? Also, maybe give us an idea what instruments you are using with it, and where being used.
Do you have a specific deficiency (use case) you are trying to address with the amp? Also, maybe give us an idea what instruments you are using with it, and where being used.
Thank you all!
WhiteDragon, all the manual says about the speaker is "One 12 in (30.5 cm) 8Ω Eminence® Ceramic". I assume this doesn't address sensitivity & cone travel. And thanks for mentioning poly fill. I would much prefer to handle poly! [FWIW: the guy who gave it to me also gave me a SWR Big Ben and looking in the back ports I thought it was stuffed with quilt batting. I wish I had a head to drive that beast!] And thanks for explaining why bass speakers are housed in so opposite a manner as guitar speakers. Adding poly fill (if there's none already) seems like plan A, cheap & easy.
And jordheis, poly fill might address my only real beef about the amp. It's very light and smaller than a 1x12 extension cab. There does seem to be either a midrange wolf resonance or mud issue. I zero the upper-mids knob or else certain notes on the D string give the ice-pick effect. My only bass is a P-bass I made myself, with a Quarter Pounder (Duncan?) pickup and flatwound strings. I'm not really a bass player. I play for my own recordings and I'm used to playing thru an Apogee Duet & KRK VXT6 monitors, uncolored. I need to learn how to adjust a bass amp and the instrument setup. Playing on direct, the string-to-string response was relatively equal, with the pickup height only ramping up a little, from bass to treble. Pretty much a factory setup. Since getting this amp, I have had to lower the E string pickup almost flush to the body, just to keep the lows from completely overpowering everything else. I like to feel a thumpy E, but this is mushy. Maybe it's noise I'm not used to hearing because my studio monitors lack a subwoofer. Or it could be my strings. Flats are comfy to play & there's no scraping, but everything else about them is inferior to round wounds, IMHO. Poor intonation, less equal mass from string to string. Somehow, these artifacts never rose to a bothersome level before I got the amp. I guess, as I write this, I have decided to try round wound strings. Perhaps that will make everything else better.
WhiteDragon, all the manual says about the speaker is "One 12 in (30.5 cm) 8Ω Eminence® Ceramic". I assume this doesn't address sensitivity & cone travel. And thanks for mentioning poly fill. I would much prefer to handle poly! [FWIW: the guy who gave it to me also gave me a SWR Big Ben and looking in the back ports I thought it was stuffed with quilt batting. I wish I had a head to drive that beast!] And thanks for explaining why bass speakers are housed in so opposite a manner as guitar speakers. Adding poly fill (if there's none already) seems like plan A, cheap & easy.
And jordheis, poly fill might address my only real beef about the amp. It's very light and smaller than a 1x12 extension cab. There does seem to be either a midrange wolf resonance or mud issue. I zero the upper-mids knob or else certain notes on the D string give the ice-pick effect. My only bass is a P-bass I made myself, with a Quarter Pounder (Duncan?) pickup and flatwound strings. I'm not really a bass player. I play for my own recordings and I'm used to playing thru an Apogee Duet & KRK VXT6 monitors, uncolored. I need to learn how to adjust a bass amp and the instrument setup. Playing on direct, the string-to-string response was relatively equal, with the pickup height only ramping up a little, from bass to treble. Pretty much a factory setup. Since getting this amp, I have had to lower the E string pickup almost flush to the body, just to keep the lows from completely overpowering everything else. I like to feel a thumpy E, but this is mushy. Maybe it's noise I'm not used to hearing because my studio monitors lack a subwoofer. Or it could be my strings. Flats are comfy to play & there's no scraping, but everything else about them is inferior to round wounds, IMHO. Poor intonation, less equal mass from string to string. Somehow, these artifacts never rose to a bothersome level before I got the amp. I guess, as I write this, I have decided to try round wound strings. Perhaps that will make everything else better.
I installed round wound strings and that improved the string to string volume disparity & the intonation, such that instrument sounds alright with the pickup adjusted to factory height. I rashly set it up with the action too low. Buzzy.
The amp sounds ok with all the EQs at center. Not fantastic, but good enough for now. The E string still sounds somewhat overhyped to me. Based on my own playing; I've never taken a bass lesson. 🤔
The amp sounds ok with all the EQs at center. Not fantastic, but good enough for now. The E string still sounds somewhat overhyped to me. Based on my own playing; I've never taken a bass lesson. 🤔