Fender Rumble Club

[M-Mittlesteadt]

Ports. They are there to tune the cab. That's all they are for. Doesn't matter where they point, their shape, length, etc. (aside from the tuning function). They are the way they are to work with the speaker in that cab design. They aren't replicating what speakers are for. No one hears the tone of a cab from the ports (except for an extremely limited frequency).

I used to design and build speaker cabs and I get why people enjoy experimenting. But the importance bestowed on ports for tone (partially stuffing or sealing them) is somewhat misguided, even though circumstantial evidence and personal belief says it work for them. Hey, if you like it when you mod the ports, go ahead. All you are doing is retuning the cab to less than ideal (given the speaker/cab parameters), even if you do end up liking that more.

 

[ValerieK]

Speaking of ports, has anyone already measured/modeled the stock tuning or tuning change for the Rumble 100 by blocking 1 port? Or changing the length of the stock size ports?

I saw a lot of discussion about it on the 40 watt cabinet but haven't found it for the 100. (I'm testing a Celestion BN12-300S in my 100, so far without touching the ports. Would like to get an idea of what to try if I want to mess with the tuning)

Cheers

 

[toughluck]

Ports. They are there to tune the cab. That's all they are for. Doesn't matter where they point, their shape, length, etc. (aside from the tuning function). They are the way they are to work with the speaker in that cab design. They aren't replicating what speakers are for. No one hears the tone of a cab from the ports (except for an extremely limited frequency).

I used to design and build speaker cabs and I get why people enjoy experimenting. But the importance bestowed on ports for tone (partially stuffing or sealing them) is somewhat misguided, even though circumstantial evidence and personal belief says it work for them. Hey, if you like it when you mod the ports, go ahead. All you are doing is retuning the cab to less than ideal (given the speaker/cab parameters), even if you do end up liking that more.

I mean, plugging ports is essentially sealing the sub. A lot of speakers come with port bungs. I had a subwoofer that specified frequency extension for all three ports working, two ports plugged and all ports plugged (essentially sealed). Bass was extended at the expense of max SPL. With EQ, it was possible to flatten the frequency response to get it even and take advantage of the bass extension.

I'm just wondering whether it's sensible to plug ports that are advertised as two-function (cabinet tuning and speaker cooling). I don't even own a 5-string bass (yet), I'm only considering that when playing a 4-string loudly, port chugging is audible.

??? Are you having a problem hearing low frequencies from your Rumble Studio 40? Mine seems to do quite well with the low notes on my BEAD-tuned basses, without reinforcement, even at acoustic gig volumes.

Perhaps this thread will help you some.. I found The Elder Equine's first post there, of many, very helpful to me, personally. In fact, he had me at "I have designed custom cabinets (cabinet systems) that will in fact capture the low B at better than -3dB for some touring players who wanted to go to that place, the were fairly large, they were fairly expensive and in the end the low frequency extension wasn't as musical as the concept suggested. ... I found that the bass signal fit into the mix better, with more tonal definition when high-passed around 40-45Hz." That's when I stopped worrying about the very low fundamentals. I just go with my ears and it sounds good to me.

But, maybe that's just me.

Nah, it's not just you. I went ahead and made more tests with my Hi-Fi and subwoofer. A simple equal temperament C Major scale from C2 upwards sounds musical.
C1 to C2 sounds distorted and needs to be played very slowly to even sound like a scale. G Major from G0 to G1 is unrecognizable as a scale.

I'd still like to get at least some of the fundamental for the seismic value, but you're right that it's not necessary for the music.

 

[M-Mittlesteadt]

Speaking of ports, has anyone already measured/modeled the stock tuning or tuning change for the Rumble 100 by blocking 1 port? Or changing the length of the stock size ports?

I saw a lot of discussion about it on the 40 watt cabinet but haven't found it for the 100. (I'm testing a Celestion BN12-300S in my 100, so far without touching the ports. Would like to get an idea of what to try if I want to mess with the tuning)

Cheers

Why do you want to alter the tuning? The tone controls on the amp are your best method of altering the tone. If it's not to your liking (and many people just don't like the baked in stock tone of the Fender Rumbles), there are tons of other cabs available.

The ports tune that cab, specifically for that speaker. Nothing more, nothing less. Every change made to the stock ports require a change elsewhere and it's all by guessing.

If you want to get an idea of what to try...Start with something like WinISD (or any cab tuning software) and get the T/S parameters for the speaker you want to try. The cab size and ports of the Rumble may not be anywhere near what you need. But you need to know what the speaker parameters are first., and build from there. Plug the numbers in and you'll know right away without even touching the cab itself.

Personally, after years of designing and building bass cabs, I'd rather reinvent the wheel than to jump into that rabbit hole again.

 

[M-Mittlesteadt]

I'm just wondering whether it's sensible to plug ports that are advertised as two-function (cabinet tuning and speaker cooling).

Ports aren't enough of an opening to cool the speakers as speakers don't get hot. Speakers have (as part of their T/S parameters) the thermal ratings of the voice coil, (e.g - watts used before melting them). Ports won't change that.

EDIT: The Rumbles are full range speakers cabs, not subs.
EDIT: It's "chuffing", not chugging.
EDIT: Trying to audibly reproduce any low notes at the fundamental frequency in a bass cab is not worth chasing after.

 

[ValerieK]

Why do you want to alter the tuning? The tone controls on the amp are your best method of altering the tone. If it's not to your liking (and many people just don't like the baked in stock tone of the Fender Rumbles), there are tons of other cabs available.

The ports tune that cab, specifically for that speaker. Nothing more, nothing less. Every change made to the stock ports require a change elsewhere and it's all by guessing.

If you want to get an idea of what to try...Start with something like WinISD (or any cab tuning software) and get the T/S parameters for the speaker you want to try. The cab size and ports of the Rumble may not be anywhere near what you need. But you need to know what the speaker parameters are first., and build from there. Plug the numbers in and you'll know right away without even touching the cab itself.

Personally, after years of designing and building bass cabs, I'd rather reinvent the wheel than to jump into that rabbit hole again.

I'll take that answer as a no.

Thanks for the help.

 

[M-Mittlesteadt]

I'll take that answer as a no.

Thanks for the help.

I was serious. Get the T/S parameters of the speakers you want to use and plug those numbers into WinISD (or similar software). You'll know immediately what size box they should go in and give you different graphs for different tuning via the ports and what to expect over the frequency range. Everything else is just a guess and about as fruitful as throwing darts at a dartboard.

It's not rocket science. But it is speaker/cab science.

 

[ValerieK]

To be more clear, I'm asking this same question in part (also curious to know if anyone has measured or modeled the stock tuning or the tuning with one port blocked):

Post in thread 'Best 4 Ohm Driver for a Fender Rumble 100 Combo'

Jul 20, 2025

Let's put the info in one post and see if anyone feels motivated.

Request Modeling for:
Celestion BN12-300S (4)

Box Properties:
Internal Volume: 1.3 Cu. ft
Two Ports: 3" diameter x 2.25" length

• Wasnex

• 

I wasn't asking how to do it, but whether anyone had already done it and was willing to share the information. Maybe I'll do it myself and also refuse to share in the future?

 

[M-Mittlesteadt]

To be more clear, I'm asking this same question in part (also curious to know if anyone has measured or modeled the stock tuning or the tuning with one port blocked):

Post in thread 'Best 4 Ohm Driver for a Fender Rumble 100 Combo'

Jul 20, 2025

Let's put the info in one post and see if anyone feels motivated.

Request Modeling for:
Celestion BN12-300S (4)

Box Properties:
Internal Volume: 1.3 Cu. ft
Two Ports: 3" diameter x 2.25" length

• Wasnex

• 

I wasn't asking how to do it, but whether anyone had already done it and was willing to share the information. Maybe I'll do it myself and also refuse to share in the future?

Old school method...

You can take the stock cab, lie it on it's back, take the speaker grill off and sprinkle some salt on the speaker. Run a sound generator through the cab, sweeping through the frequencies. When you see the salt stop moving, that's the tuning frequency.

Block one port and do the test again. The tuning frequency will be different. But, keep in mind, the tuning frequency has little to do with it's overall tone/sound or whether anyone likes that sound. The tuning frequency for a given cab is just the manufacturer's idea of the ideal tuning of that speaker in that cab.

All I'm doing is sharing what I know from past experience. It can be fun to experiment. It used to be fun for me. I'll never do it again. I'd rather spend my time playing and buy what works for me stock. But that's me.

 

[ValerieK]

Old school method...

You can take the stock cab, lie it on it's back, take the speaker grill off and sprinkle some salt on the speaker. Run a sound generator through the cab, sweeping through the frequencies. When you see the salt stop moving, that's the tuning frequency.

Block one port and do the test again. The tuning frequency will be different. But, keep in mind, the tuning frequency has little to do with it's overall tone/sound or whether anyone likes that sound. The tuning frequency for a given cab is just the manufacturer's idea of the ideal tuning of that speaker in that cab.

All I'm doing is sharing what I know from past experience. It can be fun to experiment. It used to be fun for me. I'll never do it again. I'd rather spend my time playing and buy what works for me stock. But that's me.

It's OK to just say that you don't know the answer - or not even reply at all - if you don't know. Thanks for continuing to treat me like a brain dead child though.

 

[M-Mittlesteadt]

It's OK to just say that you don't know the answer - or not even reply at all - if you don't know. Thanks for continuing to treat me like a brain dead child though.

I don't know the answer because I don't have the time to do what I suggested you should try.

Best of luck. Hope someone replies to you in a helpful way.

 

[toughluck]

Ports aren't enough of an opening to cool the speakers as speakers don't get hot. Speakers have (as part of their T/S parameters) the thermal ratings of the voice coil, (e.g - watts used before melting them). Ports won't change that.

EDIT: The Rumbles are full range speakers cabs, not subs.
EDIT: It's "chuffing", not chugging.
EDIT: Trying to audibly reproduce any low notes at the fundamental frequency in a bass cab is not worth chasing after.

Chuffing, duh

Thanks for the correction

As for cooling the speakers and "speakers don't get hot", well, they do:

Power Handling Vs. Efficiency

Elliott Sound Products - Loudspeaker Power Handling Vs. Efficiency. What are the tradeoffs? Flux modulation and thermal compression effects in dynamic drivers

sound-au.com

We get at least 95% of energy delivered to the speakers as waste heat. At 100 watts, the speaker is dissipating 95 watts constantly and it will get hot. As the coil gets hotter, resistance increases, limiting the power somewhat, but it's still enough to keep it hot.
A lot of sealed powred subwoofers (with plate amps) from between roughly 1995 and 2015 died a premature death from heat when the combined waste heat from the Class-AB amplifier and dissipated by the speaker heated up the air inside the cabinet enough to boil the capacitors. Ca. 2015 is a watershed moment because since about then solid state capacitors and Class-D amplifiers became ubiquitous.

With no plate amplifier (and it being class-D anyways), and with the fairly large volume, I would hope the speaker doesn't get too hot, and I'm aware ports only help so much (especially since they're at the bottom), but I'm somewhat risk-averse.

 

[G-Dog]

Speaking of ports, has anyone already measured/modeled the stock tuning or tuning change for the Rumble 100 by blocking 1 port? Or changing the length of the stock size ports?

I saw a lot of discussion about it on the 40 watt cabinet but haven't found it for the 100. (I'm testing a Celestion BN12-300S in my 100, so far without touching the ports. Would like to get an idea of what to try if I want to mess with the tuning)

Cheers

posted in another thread: ... ... I'm just a dumb guitarist, but I started playing bass this year and am now playing it out with 2 bands. Everything is direct with IEM's so I didn't even own a bass amp for 6 months... Recently starting to turn down playing opportunities, I shopped around and bought a cheap used Rumble 100 last week... and today ordered a cheap used 4 ohm Celestion BN12-300S for it. ... ... ...

posted in that other thread: ... ... playing afro-jazz and started with a Rumble 100 recently. It's... fine?

It looks classy and makes enough noise. I'm still working on getting an inspiring tone out of it. It's the only real amp I have ever owned, I run DI and IEM in other bands. ... ... ...

Yo, Val! @ValerieK, you are now member #1880 in the Fender Rumble Club. Congratulations and welcome. Please put that number in your TalkBass Signature for safe keeping. Then make yourself at home here and on your Rumble Club Wiki page, the repository of all Rumbling wisdom and knowledge.

See the Rumble Speaker Replacements sub-section of your Rumble Club Wiki page for some tales that may be of interest to you. Hope this helps. Please let us know here if you find what you're looking for.

Are those two excerpts from the other thread a good representation of your bass experience in general, and your Rumble journey in particular? That's cool, if so. Otherwise, we'd be glad to hear more from you. You're gonna fit right in here since we have all kinds. But we all love to ... ... ...

Rumble On!​

 

[John D Harris]

Sooo... I tried my Rumble 40 Studio and my Rumble 1×15 cab with a 100 W head and see how low they go before they bottom out and no longer play the fundamental. I used Szynalski's Online Tone Generator to play a pure sine wave through the speakers.
And here's what I found.

The Studio plays A1 (55 Hz), but it struggles a bit. It can almost play E1 (~41 Hz) at a significantly increased volume but it doesn't make any sense to do it live.

The 15" cab can play A1 effortlessly, but the ports are tuned somewhere between E1 and A1, so at E1, there's port chugging, which obviously gets worse at B0 (~31 Hz). Now, if you plug the ports, it plays E1 effortlessly and you can hear B0 with some distortion.

I figure with 30 Hz port tuning, it could play B0 perfectly, but I didn't do calculations for cab volume whether it will still be large enough after making the ports longer.

Bummer.

So here's what I'm wondering: Does the 2×10" cab have lower frequency response than the 1×15"? Which Rumble goes the lowest? Does any of them actually play B0 at a reasonable level in the mix? It almost feels like chasing the ultimate LF extension of those cabs makes no sense if a small 10" dedicated subwoofer in my home setup easily plays back 40 Hz and with EQ, it handles down to 35 Hz.

Alternatively, I could play back with the ports plugged, but then there's loss of ventilation and the speaker is no longer as effectively cooled which may be a problem at 100 watts.

Any advice?

Sine waves (except for maybe bass synth stuff) is not what bass guitars produce.

The second harmonic is much more important than the fundamental (except possibly for Reggae or EDM).

The human brain fills in the fundamental on the lower notes from the second harmonic.

If you try to adjust the ports to go lower than the driver(s) are designed for, you are much more likely to damage the driver(s).

There are cabinets designed to go down to 31Hz or lower, but they are generally fairly expensive.

Barefaced, Bergantino, Mesa, Genzler, GR Bass, GK make cabinets that will get you in the neighborhood.

Or you could go with an Electro-Voice’s Evolve 90 Active Column PA system.

Another thing about systems that go that low, they can really muck up the sound of the band both on stage and out in the room.

 

[ValerieK]

Yo, Val! @ValerieK, you are now member #1880 in the Fender Rumble Club. Congratulations and welcome. Please put that number in your TalkBass Signature for safe keeping. Then make yourself at home here and on your Rumble Club Wiki page, the repository of all Rumbling wisdom and knowledge.

See the Rumble Speaker Replacements sub-section of your Rumble Club Wiki page for some tales that may be of interest to you. Hope this helps. Please let us know here if you find what you're looking for.

Are those two excerpts from the other thread a good representation of your bass experience in general, and your Rumble journey in particular? That's cool, if so. Otherwise, we'd be glad to hear more from you. You're gonna fit right in here since we have all kinds. But we all love to ... ... ...

Rumble On!​

I mostly play and teach guitar, so getting into the specifics of bass playing and gear is new to me. I've been working on afro-jazz like Richard Bona, plus reggae tunes with one band - and indie rock in another. It's all IEM in both so I don't really know much about amps specifically.

I also coach for a rock camp type program and we use Rumble 25's and Champion 20's with Squier basses and guitars. It's impressive how good the whole package sounds for how cheap/small/light everything is - across the board it's all solid enough gear. That's why I started with the Rumble 100 - it's light and cheap and might be a good base for simple mods.

I'm itching to try fretless bass next to see if I can replace the guitar as my primary instrument. So far I haven't been able to really achieve, find, or honestly even define exactly what I want in an expressive lyrical tone on the bass. I'm sure most of it is in my hands.

 

[John D Harris]

Speaking of ports, has anyone already measured/modeled the stock tuning or tuning change for the Rumble 100 by blocking 1 port? Or changing the length of the stock size ports?

I saw a lot of discussion about it on the 40 watt cabinet but haven't found it for the 100. (I'm testing a Celestion BN12-300S in my 100, so far without touching the ports. Would like to get an idea of what to try if I want to mess with the tuning)

Cheers

Generally, when you don't get replies to a question, no one knows the answer or they have not seen the question yet (things seem to move a bit more slowly on talkbass than I remember back in the day, which seems like it should be the opposite of that).

Does your R100c have an 8 Ohm or 4 Ohm driver?

Mine has a 4 Ohm driver and !!!***you should only replace the OEM driver with a driver that has the same impedance***!!!.

I put a Celestion BN12-300S (4) in mine and it is smoother in the upper midrange, louder, and (slightly) lighter - unless you are needing the extra volume, I'm not sure it is enough of a difference to be worth the retail price of the Celestion (I got mine used at a decent price).

I haven't figured out how to plug the T/S parameters into BoxSim, yet (I looked at it a little bit, but didn't spend enough time to sort it out as it doesn't seem very user friendly), but it performs well enough with the existing ports that I'm not sure it matters.

I did not try stuffing one of the ports - seems like the designers of this level of equipment usually know what they are doing.

I can push the combo harder at lower frequencies without it losing its composure (I also use a HPF).

 

[John D Harris]

I mostly play and teach guitar, so getting into the specifics of bass playing and gear is new to me. I've been working on afro-jazz like Richard Bona, plus reggae tunes with one band - and indie rock in another. It's all IEM in both so I don't really know much about amps specifically.

I also coach for a rock camp type program and we use Rumble 25's and Champion 20's with Squier basses and guitars. It's impressive how good the whole package sounds for how cheap/small/light everything is - across the board it's all solid enough gear. That's why I started with the Rumble 100 - it's light and cheap and might be a good base for simple mods.

I'm itching to try fretless bass next to see if I can replace the guitar as my primary instrument. So far I haven't been able to really achieve, find, or honestly even define exactly what I want in an expressive lyrical tone on the bass. I'm sure most of it is in my hands.

Very cool!

Listen to "Tribal Tech" album by Tribal Tech; or "No Sweat" or "Bent" by Gary Willis band - Gary Willis on 5 string fretless bass guitar.

BTW, the parameters are different between the 4 Ohm and 8 Ohm BN12 drivers, so they will sound somewhat different.

 

[tom-g]

To be more clear, I'm asking this same question in part (also curious to know if anyone has measured or modeled the stock tuning or the tuning with one port blocked):

Post in thread 'Best 4 Ohm Driver for a Fender Rumble 100 Combo'

Jul 20, 2025

Let's put the info in one post and see if anyone feels motivated.

Request Modeling for:
Celestion BN12-300S (4)

Box Properties:
Internal Volume: 1.3 Cu. ft
Two Ports: 3" diameter x 2.25" length

• Wasnex

• 

I wasn't asking how to do it, but whether anyone had already done it and was willing to share the information. Maybe I'll do it myself and also refuse to share in the future?

The T/S parameters for the stock speaker are unknown. That‘s why you didn’t get an answer.

 

[shirojiro]

Hi folks,
I couldn't remember if I had posted this or not - I searched and couldn't find a post about it...

Anyways, I finally got around to attaching a Bag End S15 cab to the Rumble 500 combo.
I had been eyeballing the Fender 210 matching cab because I like the stacking and magnetic feet and the whole stack looks super cool.

BUT the Bag End + rumble 500 sounds pretty great. I am wondering if the Rumble speakers are less sensitive than the Bag End 15" because my perception is that a lot or most of the sound is coming from the Bag End, despite it being underneath the combo amp.

But either way, it sounds great with a very clear high end and is very loud. Maybe too loud for my practice room. I'm often a little confused when people say that the Rumble amps are muddy. I haven't found that with the Rumble 500, but I do boost the mids and cut the bass an treble a bit. (About 10, 2, 2, 10 o'clock on the dials)

Anyways, for those who hadn't tried this combination of 500 combo and a Bag End 15 - it sounds great as one might expect.

 

[ValerieK]

The T/S parameters for the stock speaker are unknown. That‘s why you didn’t get an answer.

It's my understanding that the box tuning itself is not dependent on the driver. Example from the Rumble 40 discussion:

Post in thread 'Fender Rumble v3 40 - First Impressions'

Mar 22, 2016

I have a used Rumble 40 incoming and will try out some other drivers and port tunings like you did. Do you still have your notes concerning net internal volume and the tuning of the stock ports with both open and with one closed? If you have those I can start the simulations even before the combo gets here....

Here is the info: 1.12 cf, 74 Hz w. 2 ports, 55 Hz w. 1 port. Note that once you have your amp, you can back calculate the tuning knowing the box volume and port dimensions (inside diameter and length).

I found that while modeling allowed me to determine if a...

• AstroSonic

• 

Here is the info: 1.12 cf, 74 Hz w. 2 ports, 55 Hz w. 1 port. Note that once you have your amp, you can back calculate the tuning knowing the box volume and port dimensions (inside diameter and length).

Is AstroSonic wrong or lying here?

Before you lecture me, I'm aware that the -preferred- tuning of an enclosure might be dependent on the driver and other parameters (use case), but simply calculating the existing port tuning doesn't require any driver parameters. No?