Last Updated on April 29, 2023 by Teemu Suomala
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 my findings with you.
Quick answer:
Why are guitar amps open in the back?: There are 2 main reasons:
- Open back gives amps with vacuum tubes ventilation and prevents the tubes from heating too much.
- 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 at cool stuff like:
- Why open-back guitar amplifiers were used in the first place?
- Why closed-back amps were invented?
- How do 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!
Author: Teemu Suomala
Why Open-Back Guitar Amplifiers Were Used In The First Place?
Back in the day, big amps included both the amplifier and the speaker. These big boxes also included vacuum tubes which were used to increase the power (amplify) 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 prevent 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.
What Is The Difference Between Open-Back and Closed-Back Amp?
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 at 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 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.
Our Favorite Music Store in The World!
Why?
– Excellent Customer Service (4.7/5 Trustpilot Score)
– Fast & Free Shipping
– Gear is Inspected, Tested, & Ready to Play When it Arrives to You (We love this)
– Fair Prices
Visit Sweetwater:
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:
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 on the left side and solid-state amps on the right side):
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.
If you are in search of a budget level amplifiers, these guides can come handy: under $100 amps & under $200 amps.
If you are a beginner, you can check out some great beginner amplifiers here.
Conclusion on Why Are Guitar Amps Open in The Back
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:
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
You might also like:
5 Best Taylor Guitars in 2023 – Get Value for Your Money
5 Best Martin Guitars in 2023 – Get Real Value for Your Money
5 Best Acoustic Guitars With Thin Neck in 2023 – Plus A List of 28 Runner-Ups
6 Best Acoustic Guitars Under $1000 in 2023 – Versatile & Sweet Tones
5 Best High-End Acoustic Guitars in 2023 – The Only Guide You Need
Passion the website– really individual friendly and lots to see!
Thanks for the positive feedback and keep rocking Brian!
Here are a few engineering facts that might help.
1. If there is a wall separating two rooms then if 10% of the wall is open, 90% of the sound will move from one room to the other. Applying this, it would seem that a back that is open 10% or more might as well be removed as far as transmission of sound is concerned. On the other hand, if what you are really going for is shaping of the sound in some way then experimenting with backs of different diffusions/dispersions, even depths, might get you a new sound you like.
2. The response of guitar speaker drivers typically fall off at lower frequencies. The open back cabinet is one of a number of methods to try and compensate for it since open-back gives the sense of more bass. Of course, manufacturers and players alike have developed different other ways of compensating.
3. With respect to solid state or tube amps the issue is what happens when they are overdriven? As long as the amplitude of the sound going through them is within the designed range then they should sound the same. However, when overdriven (as most all rock players are want to do) it is harmonics produced in the electronics that gives the nod to the tube amp. When overdriven tube produce harmonics that are much more pleasing to the ear whereas the harmonics produced by overdriven solid-state amps are less pleasing. So, it is not the case of which one more faithfully reproduces what’s played on the guitar. It is simply a case of which amp sounds better when overdriven.
Hi Paul! Thanks for taking the time to reveal your insights 🙂