Side-Ported Push Back Speaker Cabinet

You. Guitarist. You might have that sound you proudly call ‘My Sound’, and like all of us you want the recording engineer put the perfect mic on it and capture it the way you hear it. But there is something you should realize before you go shilling out some money for a studio and expecting your majik to appear on tape. Microphones are only your friend if you respect them.

All microphones are going to change your sound. They may pick up something unwanted, or instead remove that special something you liked, or they are just going to color your sound. Very much in the same way that expensive pre-amp you love adds almost nothing – but it really is there, so it is also with microphones.

You. Guitarist who gets pissy when an engineer starts trying to fuss with your ‘My Sound’. No matter how many or what mics are used, or where you want to stick ’em, your ‘My Sound’ is only going to be translated to tape (or 1s and 0s) through a small membrane and some electricity. No mic is like the human ear and should not be considered as such.

Instead, consider that they are part of the musical chain, an instrument no different from your choice of germanium in that stomp box you stuck in your signal. The engineer making suggestions (if she or he knows enough) is playing the mic very much the same way a musician plays an instrument.

Just as you might respect a proficient cello player, and you would never suggest how a cellist should play one, you should treat your engineer with the same level respect. Don’t tell them where you like to have the mic. Chances are she (or he) has been involved with a lot more musicians trying to capture their sounds and knows all about the options for recording. So ease back and enjoy the experience of being in a studio. Don’t try and fight the engineer. You might learn something new and find even better mic placement.

All that said, I am not a great engineer. A great engineer can dial in the perfect side chains on the fly. And they can tell which mic (and have lots of them) is perfect for your voice or rig. And as I said, they record a lot of people playing with other people. I pretty much only record me playing with myself… Wait. That sounds weird.

Mostly, I’m not a great engineer because I am a basicalist, meaning I stick with the basics. Clean signal, the best mics and prees I can afford, and quality playback.

I never compress during recording any more, which means I have to pay close attention to dynamics as I play, which means I have to pay attention to how things sound after each take, and that means that I am able create my sound using the playback as reference – making adjustments to the guitar sound after each take so that ‘My Sound’ gets on the actual recording and not what it sounds like to my ears when I play it in that space. Often the guitar amp in the room sounds kind of sucky while I’m making the take, but I capture the sound I want to tape because I understand that getting the right sound is a union between the microphone and the speaker (or any other instrument).

And, I am changing gears now – hold tight.
My recording experience brought me on an interesting journey which brings us to the actual subject of this now rambling essay.

I needed a new speaker because speakers reveal or hide so much of the sounds I try to capture. I wanted a 12 inch and had given away my 150 watt 2 channel Carvin because the damn thing was made in China and it buzzed often. My tube guy rebuilt the thing and couldn’t find the buzz. But man, that amp sounded good when it worked. Oh. I go side tracked. So I needed a new speaker and a cabinet.

I ordered a Jenson 35 special and still needed something to put the thing in. So I went to the local Go-‘Round and got a $20 cab with two blown speakers in it. Tossed those out and cut the 2 by 12 cab in half to make a 1 by 12 open back. But The sound bugged me.

Oh, I loved breaking in the Jenson, but, the speaker being inside the cab really bothered me. It sat behind the wood, where all speakers tend to sit, which is the stupidest thing! Why hide a speaker?

Why hide a speaker? Oh, probably for some logical reason. Probably. All cabs and combos have the speaker inside the dang things. Not only are they screwed to the back of a plank of wood with a hole cut in it, they cover the speaker with some sort of material like cloth or metal. And then, as if that destruction of tonal quality wasn’t enough, they almost always go and build an inch tall edge around the opening, just to be sure the sound waves get tripped all over itself.

So I did this thing where I took out the speaker, cut some particle board with a nice cherry veneer and then cut a hole in it, and pushed that over the cabinet face to fill in that space inside the rim of the edge I talked about earlier. THEN, I put the speaker on the outside of that, so it sat on a flat wall of veneer and no edge.

Yes, it made a big difference. And not only did it sound better playing it in the room, during recording I found so many more options to how to find new and better sound tones. Also, I found that when I tipped it back it sounded even better, more true, I could control the sound better by mic placement.

The more we play with our tools, the better we become at using them, and then one day we realized our tools are holding us back. The speaker was still limited.

I like the sound of an open back speaker cabinet, and it makes it easy to place a mic on the back of a speaker. But any attempt at that always failed for me. I never like the way that sounded (even mixed in with a front mic).

Instead, I made a design for a prototype pine wood speaker that closes the back of the speaker but opens the sides to force all the speaker energy out and forward. Not only where the sides ported open, external baffles were created to direct the sound forward (I was sure to keep these walls behind the face of the cabinet to allow room for the sound waves). Again I placed the speaker on the front, but this time I recessed the speaker so that the sound waves roll out of the cone and onto the face of the cabinet even better. Lastly I built the cabinet so that it looks like it has been pushed backward and seems about to fall (but it is stable).

I was stunned by the difference. This sounded very bright yet solid in the core. The thing just sizzles. Mic placement makes a huge difference in sound, but there were some things that still bothered me about it. One, it looks kind of junky.Also, the side baffles are just so wide and angled. It is a prototype so it did what it is supposed to do.

I wanted to know what would happen if I gave the entire box a tapered shape. So I made number two… I mean a second one:
Unfortunately, due to some learning curve about dealing with a piece cut with three different angles, I had to sacrifice height to keep from starting over. The lines are much smoother and it sounds fantastic but it is still different. It is still pine so it has some great life to it, I don’t use EQ but I would be interested in seeing how and eq pedal would work with this.

Still, the second speaker cabinet doesn’t have that same vibrant raw energy of the sloppy-cut prototype. The second has a more polished and refined sound that mimics its design and craft while still allowing it to brim with tone. It is my preferred cabinet right now, easily beating out the speaker cab of my combo and the other two cabinets I have now laying around and taking up valuable space.

I am realizing how much is ‘almost’ possible with a great speaker and cabinet situation. I do have model three in mind, but more importantly I am realizing what amazing things 150 tube watts can deliver that 5 or 18 just can’t get close to. That is the power of a great speaker situation; it shows you where your sound is lacking. It reveals your true weaknesses, kind of the way an amazing lover does. She doesn’t have to state it directly, but you can tell when something is missing, even if she’s really good at acting.

That’s where I am now, and how I got from point B of cabinet building to point H about how guitarists need to work with their engineers without any real obvious connection between the two.
But all things are interconnected.
The trick is to find all the connections and put them to use.

Maybe after model three… well, we’ll get there first.

5 thoughts on “Side-Ported Push Back Speaker Cabinet

  1. Really interesting. I was researching side ported cabinets when I found this. Seems you have intuitively taken it to the next level even though your design is actually front ported. The idea of side porting is to create what some folks call a “3D” sound. Big and wide might be more accurate. Seems your design would be pretty darn big as well. I might try extending the baffle (front) out more to the side perimeter and rather pull the side short of the front to make a similar sized opening. Maybe that won’t make any difference in dispersion to the sides.The laid back trapezoidal shape has basic inherent advantages in terms of inhibiting internal standing waves I think. but also in the way it must tend to direct the sound back out towards the openings. I might just put a sort of false flat top on it to allow for the amp to sit up there. Would also allow for also tapering down the inside lid creating a pyramid on it’s side internal shape. Even better projection towards the openings? Did you experiment much with the size of those openings? Really cool stuff.

    1. My experiments ranged from an empty speaker in the room to various fronts and sides. But there weren’t any real iterations of construction except for the prototype and this second and final product. I really like the observation that this is a front ported speaker not a side ported speaker.

      When I first started to build the second speaker cabinet I had wanted ports to be more to the side & back, with the ability to aim forward. However, I did not like the idea of creating a corner between the front panel and the side wall, having those standing waves kind of bounce around before coming back out one of the side openings. It just seemed too unpredictable and potentially ugly. It may be worth considering just shaving down the boards on the sides of the cabinet to make it pyramid shaped and side open.

      My use is for recording and not playing out, but having side ported for a show does sound pretty fun.

      I too had thought about a flat top, but then I rejected the idea because
      A) I was worried someone would put a drink up there and it would spill, and being that the speaker is mounted flush to the outside front it would be more exposed to damage from such a thing and
      B) I was concerned that by creating a box on top of the speaker it would vibrate at an unpleasant frequency. Microphones pick up that kind of stuff.

      If you decide to build one I hope you post a link to it here. I would love to see it.

  2. I think I’m going to try a 15′ cabinet first. I have an Eminence Deltalite 2515 that’s looking for a home. Eminence calls for a ported cabinet with 4 cu.ft. internal volume. Probably will use Baltic birch ply. Maybe 5/8″ and maybe experiment with some internal bracing side to sided. laid flat in the middle of the walls to help stiffen? I do want to be able to take this out to gigs so weight would be a concern. By the way I already figured out I could just run the sides up through the top and cut the top of them at the top like a parallelogram. Then just lay a top on for a flat surface. Despite being the guy who would put a drink up there ! If the back of that top space was open, or stuffed full of foam, do you think it’d vibrate ? Since I’m building it more for live playing it probably wouldn’t be as critical. Now to figure out how to calculate the volume of a pyramid?

    1. I tested a small amp head on the cabinet. Somehow it clung to the top and the whole thing started to topple over backward. A shelved model would need a kickstand or foot for balance.

  3. You have already gotten much more scientific than my (by gut) approach. I really hope you can share your progress. Feel free to leave a web site or link. I’d be interested in any of your projects.

    I wanted vibration, I was hoping for character from the wood. Supports are a good idea But you could add them later if you wanted.

    Please post a link

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