NAD - Fender Rumble V3 100

[steve_rolfeca]

In my case, I already had the hot glue gun out, to secure the dowels installed as bracing. It was a moment's work to spritz a couple of lines of glue on each pane (at the low heat setting) just to make sure that the quilt batting stayed put.

I used plywood ovals to block my ports. Put a carriage bolt through each oval, with a little crosspiece at the back. Tightening the bolt sandwiched the port tube between the oval at the front, and the crosspiece at the back, sealing the port.

Overly complex (why not screw or glue the ovals to the baffle and be done with it?), but I had only just bought the amp, and wanted to keep the mod reversible.

 

[steve_rolfeca]

So just curious how you're feeling about this amp now that you've used it with the mods for a while. Just picked one up on a pretty good deal and it's OK but really boomy for my tastes and I'm not able to dial it out. Thinking about doing the mods you listed here if it will in fact tame the boxy low end and tighten it up.

Totally worth it.

Nice sounding little amp stock, but the boom made it sound like a small amp that was trying too hard.

With the low mids tightened up, it turns out that there's a nice, complex growl down low. You can still dial in Astra bass if you want to smooth it out, but with the controls at noon, that growl makes it sound expensive.

I like it better now, than the AER amp that caught my ear at about 5x the price...

 

[Linnin]

Give that man a burger!

 

[Awesome Sauce]

I had only just bought the amp, and wanted to keep the mod reversible.

That's the only reason I didn't attach the batting in mine- the 'just in case' factor.

 

[ticol07]

I saw this thread and then applied your bracing method on my TC Electronic bg250 combo.
And I have to say, I am very impressed by the result.
Its sound is way nicer now especially in the lows and the mids. It sounds less boomy and more defined.
Thanks for your clear explanations !

Edit : I didn't glue the braces, I just screwed them because I wanted to be able to remove it if it didn't sound right. Is glue necessary or just an option to be sure nothing will move ?

 

[steve_rolfeca]

Priorities...

I didn't screw my braces in, because I didn't want to drill holes in a new amp.

Screwed without glue is more likely to buzz or rattle in the long haul. But if it isn't making noise now, I wouldn't worry about it.

 

[AstroSonic]

Steve,

What is the diameter and length of the ports?

My Rumble 40 was a little boomy and the bass was mainly 'harmonic' below A (E string). The overall tone was decent, with a really nice mid-band presence. I am sure that many will find the stock tone to their liking. I preferred the tone with one stock port, although sealed was also a marked improvement to my ears. I noticed that the sealed and one port tuning had a lot more excursion going on than the stock alignment, and that the driver could sound strained at moderate volumes - the stock tuning had minimal excursion and never sounded strained. The driver had a relatively small ceramic magnet for a bass guitar 10 inch driver (20 oz?). Its sensitivity was low to moderate, and its TS parameters were most suited to a sealed box. Modeling runs suggested that the stock tuning was the best all around ported alignment. The one port tuning sounded markedly better to my ear, but modeling indicated that excursion could be an issue - my experience bore this out. After a few weeks use I replaced the stock driver with an S2010 and retuned the enclosure, which took the combo's performance to a whole new level. Lining the back and two sides smoothed out the sound. No additional bracing was required as the stock cab exhibited minimal vibration. A big plus for the Rumble enclosures is that they are of adequate internal volume - they did not just stuff the largest driver they could into a small box, as many do.

 

[ticol07]

Priorities...

I didn't screw my braces in, because I didn't want to drill holes in a new amp.

Screwed without glue is more likely to buzz or rattle in the long haul. But if it isn't making noise now, I wouldn't worry about it.

Ok.
It's the first time I upgrade a cab, so I wasn't sure with myself
I had to exerce some force to put the braces in the good position as I cut them 1 or 2 mm longer than the internal dimensions of the cab. So I don't see them moving easily. And I used very long screws. But if I feel the screws get a bit loose in time I'll use some glue.
I could test it at rehearsal yesterday and I had a very beautiful tone. No more need to cut some bass to prevent boomy tone, and mids were way more musical.
It's so simple and cheap. It could have been done directly by the manufacturer...

 

[kringle77]

Im going to try out a 500 2x10 combo and had already thought about replacing the woofers with a pair of S2010 drivers as well as adding some batting. I may even try adding bracing too. How do you get the dowels in there? Seems like it would nearly impossible to get them in there at an angle and then get the flat ends to but up against the walls tightly.

 

[AstroSonic]

Im going to try out a 500 2x10 combo and had already thought about replacing the woofers with a pair of S2010 drivers as well as adding some batting. I may even try adding bracing too. How do you get the dowels in there? Seems like it would nearly impossible to get them in there at an angle and then get the flat ends to but up against the walls tightly.

For bracing I would try gluing 1/2 inch x 3 inch plywood, edge-on, across the large panels - easier and more effective than trying to fit dowels, though either is an improvement. The Rumble V3 boxes are made from 1/2 inch plywood. Joints have limited bonding area. Installing a dowel that either pulls panels inward or forces them outward may compromise those joints in the long run.

For the driver, check the internal volume. The S2010's TS parameters are optimized for relatively small boxes (under about 1.4 cf per driver). From about 1.3 - 2.2 cf the Deltalite 2510 II is optimum. Either will 'work' in larger and smaller cabs, but there are good reasons to design for the middle ground.

 

[ticol07]

There's something I don't understand: is there a risk for the speaker when plugging the ports or is it just a tone preference ?
I get it that by removing the low mid bump due to the port there's some perpection of volume diminution, but will the speaker more stressed or more sensitive to a push of the lows ?

 

[AstroSonic]

There's something I don't understand: is there a risk for the speaker when plugging the ports or is it just a tone preference ?
I get it that by removing the low mid bump due to the port there's some perpection of volume diminution, but will the speaker more stressed or more sensitive to a push of the lows ?

The ported cabinet loads the driver to a little below 'E', so cone motion is very well controlled. The downside is that there is a very strong upper bass peak - it makes the volume markedly uneven as one plays across the peak. The strong peak also alters attack and sustain as you play across the peak. this alignment was quite intentional, as on casual audition, the combo has surprisingly strong bass, and is very fart-out resistant. The sealed alignment greatly reduces the peak and actually has deeper bass (a lower f3). It also plays more evenly and sounds like it has stronger deep bass. The downside is that it has more cone excursion through the mid and low bass. The 40w combo amp can stress the speaker. I did not push it enough to get it to make a 'clack', but it can sound obviously strained. at least, you will clearly hear it being overdriven before any damage is done. Its pretty loud when this happens, so its more than usable sealed (or with one port - maybe try both).

 

[kringle77]

On thursday I will have a pair of s2010 drivers for ny rumble 500 which will flatten out the hump and give lower response as well as better power handling. Should be a big improvement. Combo has been totally lined with 1" foam.

 

[Britbonic]

Great explanation! I had one of these and really wanted to make it work. Added polyfil and 2 dowels to brace the cab. Temporarily blocked the ports with some plywood but still couldn't reduce the low mid bump enough. I completely understand why they design it this way. It demos very well in the showroom. It's a shame because the amp itself is really quite nice. I was really impressed with the sound through headphones. I'm sure they never would but if fender decided to do a Pro version of these amps with a better sounding speaker/cab they would sell a lot of them.
Btw isn't the Rumble 100 a 100 watt amp or it that just a 4 ohms?

 

[ticol07]

The ported cabinet loads the driver a little below 'E', so cone motion is very well controlled. The downside is that there is a very strong upper bass peak - it makes the volume markedly uneven as one plays across the peak. The strong peak also alters attack and sustain as you play across the peak. this alignment was quite intentional, as on casual audition, the combo has surprisingly strong bass, and is very fart-out resistant. The sealed alignment greatly reduces the peak and actually has deeper bass (a lower f3). It also plays more evenly and sounds like it has stronger deep bass. The downside is that it has more cone excursion through the mid and low bass. The 40w combo amp can stress the speaker. I did not push it enough to get it to make a 'clack', but it can sound obviously strained. at least, you will clearly hear it being overdriven before any damage is done. Its pretty loud when this happens, so its more than usable sealed (or with one port - maybe try both).

Thanks for your reply.
In my case it's not the same amp as yours or the one described in this thread, it's a TC BG250. But it's the same kind of conception. High tuned port and a strong hump in the 80/100 Hz area.
With the bracing it sounds less boomy with hump, and the bass eq is set to cut at 80 Hz : in the area of the hump (I figure it's done intentionally).
So by reducing a bit the bass I feel I can remove the hump, but there's still this straight cut of the lows below.
I've tried to put some pillow in the port (it's a large rectangular one), and it sounded a lot like with the bass knob cut a bit.
But as you mention it, sealing would help to add some lower bass, which could be nice.
I never push this combo at his max, so what you say makes me more confident to make some try with something more professional than a pillow to block the port and test my amp in a band situation.
That's nice !
I love Talkbass for that : any question has a reply

 

[AstroSonic]

Great explanation! I had one of these and really wanted to make it work. Added polyfil and 2 dowels to brace the cab. Temporarily blocked the ports with some plywood but still couldn't reduce the low mid bump enough. I completely understand why they design it this way. It demos very well in the showroom. It's a shame because the amp itself is really quite nice. I was really impressed with the sound through headphones. I'm sure they never would but if fender decided to do a Pro version of these amps with a better sounding speaker/cab they would sell a lot of them.
Btw isn't the Rumble 100 a 100 watt amp or it that just a 4 ohms?

I think the manufacturers know that they sell more combo's when they audition well on a short audition, and that, since most combo purchasers are beginners,a really bassy amp sounds impressive. I think these new Fender Rumbles are very well designed, and, with a 5 year warranty, are likely to be long lasting. The electronics perform very well: wide band, transparent, low distortion, versatile EQ. And the cabs are well made, if not as well finished (behind the grill) as some. IMO, they are a product line that begs for a factory driver upgrade like many companies used to do: 'Special Design' (or other OEM) as an entry level, with an upgrade to JBL, Altec, or EV as an upgrade. An upgraded driver and optimized tuning totally transforms these combos.

 

[ticol07]

I didn't find a way to block the port for real. It is a shelf port (is that the good name ? I mean, a rectangular port at the bottom of the cab. The bottom of the cab is the bottom of the port. The sides of the cab are the sides of the port. The top of the port is a rectangular piece of wood put on the top of it, at the bottom of the baffle). So, I can't fix easily something on it. I tried again with a pillow, heard the hump disappear, but it wasn't leak proof for sure. So I don't know how it really acted on the cab.

Following these experiments, I read several threads about ports, tuning, cab size,...
I measured the internal dimensions of my cab minus the port volume. I get 2.7 / 2.8 cu ft. I didn't substract the speaker and the tweeter volume.
The port is 14.6" x 2" with a 2" lenght (very short !!).
Then I played a bit with WinIsd. It gives me a cab tuning about 60/62 Hz with a 2.6 volume. But as I understood it, WinIsd doesn't calculate well with shelf port. There should be a factor of 1.5 on its length. When multiplying the port length by 1.5, I get a 58Hz tuning.
And when I send frequencies with a sinewave generator, the speaker clearly vibrates the less around 70Hz. This should give me the real tuning frequency, no ?
The difference is huge !!

Did I do something wrong ?

And if I want to lower the tuning frequency, it's better to block partly the port or to increase the port lenght ?

This science is very interesting but not intuitive for a newbie like me

 

[AstroSonic]

I didn't find a way to block the port for real. It is a shelf port (is that the good name ? I mean, a rectangular port at the bottom of the cab. The bottom of the cab is the bottom of the port. The sides of the cab are the sides of the port. The top of the port is a rectangular piece of wood put on the top of it, at the bottom of the baffle). So, I can't fix easily something on it. I tried again with a pillow, heard the hump disappear, but it wasn't leak proof for sure. So I don't know how it really acted on the cab.

Following these experiments, I read several threads about ports, tuning, cab size,...
I measured the internal dimensions of my cab minus the port volume. I get 2.7 / 2.8 cu ft. I didn't substract the speaker and the tweeter volume.
The port is 14.6" x 2" with a 2" lenght (very short !!).
Then I played a bit with WinIsd. It gives me a cab tuning about 60/62 Hz with a 2.6 volume. But as I understood it, WinIsd doesn't calculate well with shelf port. There should be a factor of 1.5 on its length. When multiplying the port length by 1.5, I get a 58Hz tuning.
And when I send frequencies with a sinewave generator, the speaker clearly vibrates the less around 70Hz. This should give me the real tuning frequency, no ?
The difference is huge !!

Did I do something wrong ?

And if I want to lower the tuning frequency, it's better to block partly the port or to increase the port lenght ?

This science is very interesting but not intuitive for a newbie like me

The tuning frequency will correspond to the frequency with minimum cone motion. Cone motion should increase above and below that frequency. I would not be surprised at 70 Hz.

You can effectively seal the cab by stuffing a towel tightly into it.

You can try changing the tuning by making a sliding port block:just a board that covers the port and has (in this case) a 2 inch right angle into the port. Make the outside board about 3 inches long, and make a couple 2-3 inch rectangles to block the port. That way you can block it in steps. Use small wood screws to fasten them.

Honestly, I wouldn't expect too much (though I could be surprised). The driver is most likely underdamped (relatively high Qts), making an improved alignment impossible.

If you like the electronics (power, sound quality and EQ), and the form factor, you can greatly improve the tone (and max spl) by upgrading the driver and retuning the cab. I would just block off the stock port and install tube ports: they are much more easily adjusted, and WINISD has a good understanding of them.

 

[ticol07]

Thanks for this explanations.
As I understood it, the internal volume of this cab is nice for a 15". So an upgrade of the driver could be very efficient.
I'll give some other tries to the port blocking and think about this driver upgrade. It could be nice.

 

[ticol07]

I put a towel really tight to black a small half of the port. It sounds very nice. Volume seems to be a bit lower on the amp, but not a lot.
If I push the amp to get strong volumes, I don't hear the cab struggling, so I guess it will be safe.
And the sound is way more even. As the amp of my combo is very flat, the result is more transparent, which is convenient as I like to use preamps to shape my tone.
I'll wait a try with my band before deciding if I do some hard work to keep the port closed a bit.
But I can tell my amp sounds way nicer (according to my tastes and my ears) than a week ago. Just have to pass the full mix test
Thanks for all the advices.