Why Are Guitar Amps Open in The Back? – History Explained

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This question has come to my mind again and again: why some guitar amps are open in the back? The first time was probably in 2009 when I bought my first amp. I decided to dig deep…and after some digging, I found answers. And now I’m about to share these answers with you.

Quick answer:

Why are guitar amps open in the back?: There are 2 main reasons:

  1. Open back gives amps with vacuum tubes ventilation and prevents the tubes from heating too much. 
  2. Open back is also used because of the different sound it provides (more open and room-filling). 

But I’m happy to share more cool info with you. We’ll look cool stuff like::

  • Why open-back guitar amplifiers were used in the first place?
  • Why closed-back amps were invented?
  • How open-back and closed back amps sound?
  • How to get more direct sound out of the open-back amplifier?
  • Which one should you choose?

Let’s get started!

photo reveals owner of guitaristnextdoor.com

Author: Teemu Suomala

I first grabbed guitar in 2009. I started this website in January 2020 because I couldn’t do window installation anymore due to my health problems. I also noticed that most guitar websites don’t do a really good job, so I decided to just go for it! I got lucky and managed to get awesome people to help me with my website. I also got lucky because I have you visiting my website right now. Thank you. I do all this for you guys. If you have any recommendations, tips, or feedback, just leave a comment, I would love to chat with you. I have been fortunate to produce content for several large guitar websites, such as Songsterr, Musicnotes, GuitarGuitar, and Ultimate Guitar. I spend my spare time exercising and hanging out with my wife and crazy dog(I guess that went the right way…).


Why Open-Back Guitar Amplifiers Were Used In The First Place?

Old open-back guitar amplifier

Back in the day, big amps included both the amplifier and the speaker. These big boxes also included the vacuum tubes which were used to increase the power of the sound signal. And oh boy, those tubes heated when used. With the open back, air could flow in easily and give the tubes ventilation and prevented them from heating too much. This is the reason for the use of the open-back in the first place.

Without the open back tubes could heat too much and break or tubes could even start a fire. So the open-back was and still is a smart and safe invention.

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What Is The Difference Between Open-Back and Closed-Back Amp?

image reveals how speaker cabinets design (closed vs open-back) affects speakers behavior
You can see that the back panel design affects speakers behavior.

Open-back

In open-back amps, vacuum tubes are usually used to increase the power of the signal and amplify the sound. This gives the amp a different sound than a solid-state amp. Many guitarists share a common opinion that the valve/tube amps sound the best when the volume is on the loudest. 

But sometimes solid-state amps have open-back too. The reason for this is the different sounds that the open-back provides.

When you strum your guitar and the cone of the speaker pushes out, the speaker sucks air in. With the open back, the speaker can get unlimited amounts of air, and the cone of the speaker can move a lot looser. And that helps with low-end frequencies. That’s why the open-back guitar amp has more bass than a closed-back amp.

The sound of the speaker can radiate from the front, back, and even from the sides. Because of that, the sound is soft and open. For example, if you play in your room the sound of the open-back fills the room nicely. 

Why Closed-Back Amps Were Invented?

Closed-back amps sounded great but there was a leaking problem…

When the band was performing on the stage, the open-back amp leaked sound from the back and sides. And if the drummer, for example, used mics to amplify the sound of the drums, those mics could register too much noise from the open-back guitar amp. And that could make drums sound bad. This is why closed-back amps were invented.

Basically because no one wants to mess up with how the drums sound and deal with an angry drummer after that.

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Closed Back

With the closed-back, the sound of the speaker is more directional. These amps are really tight and the sound comes only from the front. When the back of the amp is closed, the speaker can get less air in. Because of this, the cone of the speaker moves less. This makes the amp sound tighter and brighter. And in my opinion, the sound of the closed-back amp is more aggressive ”in your face sound”.

Closed-back amps use transistors to convert electric signals to sound waves and amplify the sound. This system is called “solid-state”.  Solid-state amps give great clean sounds, but some players prefer valve/tube amp when heavy distortion is used. In my opinion, this depends on your personal preference. Personally, I can’t deny that tube amps sound awesome, better than solid-states.

Note that some solid-state amps have open-back too, the reason for this is the different sound it provides.

Semi-Open Back

There are also semi-open back amps. With these, the back of the amp is slightly open, but the air doesn’t flow so freely and there is less sound leaking. Sound-wise it sits in the middle. 

I bet that you want to hear this: in this video, a solid-state amp is used to demonstrate how the type of the back panel of the amp affects the sound:

YouTube video

How to Get More Direct Sound Out of The Open-Back Amplifier?

As you saw in the previous video, you can make your amp sound different by removing or adding panels to the back. It looked that in the video plywood was used to make the amp a close-back. This might be handy in some situations, for example when you need to play with a miced drummer.

Caution: If you own a valve/tube amp don’t make it a closed-back. Those tubes need air to cool down.

Valve/Tube Open-Back Amp VS. Solid-State Closed-Back Amp Sound Comparison

As I said earlier, open-back amps usually use vacuum tubes to power up the signal. Closed back-amps use the solid-state/transistor system. This video helps you to compare the sounds of these amps(valve/tube amp is played at the left side and solid-state amps on the right side):

YouTube video

In my opinion, when the clean channel was used, both were equally great. But with distortion, the valve/tube amp had a slightly better sound on it. Really sweet and natural distortion.

Note: Valve/tube amps are more expensive and harder to maintain than solid-state amps.

Should You Buy a Closed- or Open-Back Guitar Amplifier?

The most important thing is this: which one sounds better in your opinion?

Do you want that room-filling open and soft sound of open-back? Or do you want direct, tight, and bright sound of closed-back?

In my opinion, it’s nicer to listen to soft and calm playing from the open-back amp. But when the sound needs some tightness, closed-back can give you that. I love both! But, I prefer the open back slightly over the closed-back amp. For example, the super affordable Vox Pathfinder 10 I recently tested had an open back and I just love how it sounds.

Conclusion

This video was a great help for me when I crafted this post, it also reveals one of the biggest misconceptions related to guitar amps:

YouTube video

So that’s it. I hope that this post gave you the answers you craved. Leave a comment down below and feel free to share this post too. I wish you all the best and keep rocking!

Teemu ‘’the open-back’’ Suomala


Here’s Our Favorite Gear Right Now!

Our Favorite Guitars:

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Electric guitars:

For beginners and tight-budget guitarists, Ibanez GRX70QA was the winner after hours of testing. If you are a metalhead, Jackson JS22 Dinky is our favorite.

If you have more room on your budget, Yamaha Pacifica 112V gives you a great bang for your buck, and Fender Player Telecaster HH will serve intermediate Players well.

Our favorite Electric guitar of 2021 was the PRS SE Custom 24-08. It gives so much versatility, comfort, and good tones that it’s impossible to ignore.

Acoustic guitars:

For beginners, Yamaha FG800 is our go-to guitar. It offers more than any other guitar in the same price range.

For intermediate and beginners with bigger wallets, Gretsch G5024E Rancher offers so clear and detailed tones, plus easy playability that I had to include it here.

Seagull S6 Original is the best acoustic around the $500 mark. It has the construction, sound, and feel that many more expensive guitars don’t achieve.

Our Favorite Amps:

For beginners, Fender Mustang LT25 offers the most. It’s versatile, sounds good, and is simple to use.

For most home players, Boss Katana 50MKii is the amp that serves you in any situation. From country to metal.

If you are searching for a tube amp for home use, Blackstar HT-5R MKii is my go-to option because it sounds so good, and you can adjust the wattage(power).

When it comes to acoustic guitar amps, Fender Acoustasonic 40 will serve most people really well. But our favorite is Fishman Loudbox Mini BT. It offers a professional level tone and volume with a price most people can afford.

This Post Has 2 Comments

  1. Brianphone

    Passion the website– really individual friendly and lots to see!

    1. Teemu Suomala

      Thanks for the positive feedback and keep rocking Brian!

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