Cabinet Damping

[kidA]

Okay, so as the title suggests, i'm going to bring up cabinet damping.

First though, the inspiration for my idea.

In loudspeakers (of the music reproduction kind) the goal is to isolate the driver as much as possible by solidifying the cabinet to reduce resonance and essentially let the speaker speak for itself. the cabinet material resonates at a certain frequency and it will vibrate at those frequencies, muddying the sound because the entire box will act like a speaker of sorts. simple enough.

So my question is this: Is this a concern addressed with guitar speakers as well? I know solid wood is preferable over particle or chip board. What about MDF? most all loudspeakers are made from some sort of mdf as it proves to be the best for the application. Why is solid wood preferable for cabs apart from the fact that its real wood/its more solid?

So if a cab is made from particle board, then has anyone considered damping the cab by mass loading it to reduce the resonating frequency? I'm thinking specifically of roofing stuff called peel n seel. it's thin sheets of rubberized asphalt with an adhesive side and a foil backed side. this could also double as shielding maybe? In a pair of my speakers at home i lined the cabinet with several layers of this stuff and it really cleared out the mid bass muddiness i was experiencing prior and also resulted in overall clarity. I also added some to the speaker basket to prevent unwanted resonance from the thin steel.


So, would this work/be desirable in a guitar cab? in a guitar amp application, several layers of the stuff would significantly reduce resonance in a given cab, and i would tend to think this is a good thing, but i could very well be wrong. you could also mount this on a chassis to reduce vibrations from the speakers and have less jarring... though you might be concerned about the heat from tubes...

though it might look ugly inside, it could really clear up the sound of a cheaper , or any cab for that matter. what do you guys think?

 

[voided3]

Dampening is very common in bass and PA cabs as it can make the bass deeper and sometimes reduce port flutter. I remember reading that it "tricks" the speaker into thinking it's in a larger cabinet. Guitar amps are different beasts, but the same principles apply. I think an open back cabinet would have very little if any benefit from dampening (might even be a detriment), but I have seen dampening used in sealed guitar cabinets; I have a Sonic 4x10 cab that has some in the back of the cabinet.

That said, you know how guitar amps are when it comes to things like this: things that in the pro audio world would be considered to be a terrible idea can be considered an enhancement of the tonal characteristics of an amp. Guitar amps are designed to heavily color the sound with distortion and speakers designed for the instrument's range of fundamental pitches (or even narrower in the case of small amps) and give the guitar a voice, often with the cabinet construction playing a vital role. Pro audio gear, on the other hand, is meant to be flat and have a clean sound with no distortion and good projection to accurately reproduce whatever goes into it.

This also would probably answer your question as to why plywood, solid wood, and other tone-woods are used in guitar cabs: they give a desired tonal color in addition to being more durable. Ever notice how most budget guitar extension cabs are MDF or particle board? It's a more consistent construction method, but it's heavy, not very durable, and leaves a flat sound or UNdesireable resonances because of it's density. Perhaps cabinets like these would benefit from dampening to reduce their acoustic influence on the speakers, but typically guitar amps seem to favor woods that have a positive influence on the tone without any intervention other than the shape, size and design of the enclosure. Also remember that tube combo amps can't be sealed up for ventilation reasons and having some kind of insulation come loose around hot tubes would be a bad situation.

 

[11 Gauge]

The best advice I can give is to try it - it's a relatively cheap and interesting experience.

Guitar speaker cabinets kind of counter home audio setups in every aspects...

With an audio speaker, you do want to isolate it in an attempt to remove coloration. You will probably also want to port it, to increase efficiency and limit cone movement at certain low frequencies...

With a guitar speaker, you typically want some coloration from the enclosure. Solid wood isn't a prerequisite, but it makes it easier to achieve the effect. Plywood can actually have a stronger effect, since you can typically go with a thinner piece of wood.

An open back cabinet can make things sound bigger, but typically with less projection and looser bass. While porting (a closed cab) isn't unheard of, it's fairly rare. If you know the spec's of your speakers, you can tailor the cab to resonate at a certain frequency - this has been done.

I've found particle and MDF to be excellent choices for baffle boards, where it's really critical to control what's going on with the two sides of the speaker cone. By playing with the thickness, you don't remove all of the liveliness of the speaker.

You can also cut to the chase by picking the right speaker - one that has the damping characteristics that you prefer. Some speakers are round, some are punchy, and so on. But obviously, the speaker and cab are a team, and should be designed to accomodate each other.

 

[Shnook]

You know, I've often wondered why there isn't more focus on reducing vibrations and colorations with amps/cabs in the guitar world they way there is in the audiofile world. I've seen $200 'feet' to go on a Turntable to reduce vibrations and always thought something like that for a head sitting on a cabinet would be a good idea. I know it's extreme to some but still...

The best advice I can give is to try it - it's a relatively cheap and interesting experience.

Guitar speaker cabinets kind of counter home audio setups in every aspects...

With an audio speaker, you do want to isolate it in an attempt to remove coloration. You will probably also want to port it, to increase efficiency and limit cone movement at certain low frequencies...

With a guitar speaker, you typically want some coloration from the enclosure. Solid wood isn't a prerequisite, but it makes it easier to achieve the effect. Plywood can actually have a stronger effect, since you can typically go with a thinner piece of wood.

An open back cabinet can make things sound bigger, but typically with less projection and looser bass. While porting (a closed cab) isn't unheard of, it's fairly rare. If you know the spec's of your speakers, you can tailor the cab to resonate at a certain frequency - this has been done.

I've found particle and MDF to be excellent choices for baffle boards, where it's really critical to control what's going on with the two sides of the speaker cone. By playing with the thickness, you don't remove all of the liveliness of the speaker.

You can also cut to the chase by picking the right speaker - one that has the damping characteristics that you prefer. Some speakers are round, some are punchy, and so on. But obviously, the speaker and cab are a team, and should be designed to accomodate each other.

 

[4 Strings]

Interviewer: Your cabinetwork is outstanding. Aside from their vintage appearance, what part does the cabinet play in the tone of these amps?

Victoria Amplifier founder Mark Baier: The cabinet in a Fender tweed amp is an integral element of the overall tone of the amp. It's a very resonant cabinet with lots of vibrations going on, for better or for worse (laughs), and pine is a very light and resonant wood. First-time users of our amps are always impressed by the fact that they don't miss reverb...there is a natural, subtle, resonant reverb thang happening in those cabinets. When you consider the difference between the Tweed and Blackface amps, the best difference is the cabinetry. The BF amps are really stiff and tight and those speakers are locked on, man. You need reverb to open up those BF mutha's. I think they're real tight and lifeless compared to a tweed cab, which is very loose and lively-almost vocal in character. They do have a drawback however-lots of cabinet buzz. Comes with the territory, I guess. That potential problem causes us more headaches than anything, and I'm convinced that Leo Fender changed the design of the tweed cabinets in part because of their tendency to resonate too much for their own good. Ying and Yang, baby! The whole tweed package is so coupled to itself structurally that everything plays a part. Consider the Bassman reissue Fender put out-it doesn't quite have The Tone, does it? One key element that's missing is the cabinet they chose. They opted for a denser, cheaper wood and they eliminated the box joints at the corners. Those cabinets just don't breathe and interact with the chassis the same way, in my opinion.

Read the entire article at (link removed), it is quite interesting!

 

[11 Gauge]

It's a very resonant cabinet with lots of vibrations going on, for better or for worse

I guess that one needs to decide if it's for better or for worse, and then design the cabinet appropriately.

I concur with Mark that for tweeds, a twitchy, bouncy cab is probably just the ticket - you're generally talking very low power and the crudest of circuits, so you want the enclosure to have a big impact on the overall vibe.

Mark refers to BF cabs as tight and lifeless, but just as many guitarists revel in the design. To write off Fender's tube reverb as almost a necessary afterthought because of going to a different cab is almost ludicrous. AFAIK, tube reverb was pretty much created for guys like Dick Dale, who if you made them play through a pine cab, would pulverize it to splinters in 10 minutes...

I definitely see the tweedheads points for a very bouncy cab. I can also see the BF/SF freaks' desire for a tight cab, free of buzzes, potentially farty bass, and honking resonances that can't be dialed out at higher volumes...

...Unless you are content with building straight up clones, or find yourself chained to one cabinet design method over the other, I think that the best most flexible enclosures embrace both philosophies - you can go with a thinner wood for the sides and top, and play with the baffle to get the level of control that you want.

Neither way is right or wrong, and it's really dependent on your playing needs.