Updated by Bobby
Updated on March 21st, 2022
Added the Two Notes CAB M+, the Tone King Ironman II, and the Universal Audio OX Reactive. Three attenuators in this roundup have been discontinued and have been moved to their own product table.
Best Guitar Amp Attenuator (our top pick)
Rivera RockCrusher Power Attenuator
The Rivera Mini RockRec is the highest-value amp attenuator for basic tube amp recording and playing at lower volumes. It's pricey, but since the Mini RockRec is harder to find these days, we default to the RockCrusher which is more expensive, but provides a better roster of features and all the functionality we need out of an attenuator.
You cannot use a tube amp without connecting a speaker cab to the power amp.
Without a speaker load, tube amps will burn out and then you'll be out an amplifier.
This is a problem is because, while a lot of guitar players prefer tube amps, it isn't always ideal to have to use a speaker cab or to play at high volumes (where tube amps are often at their most optimal tone quality). This is especially true when you're dealing with combo amps or tube amp heads. What if you want to record or go straight into a PA system? In order to do that, you need something to - in a sense - shoulder the speaker load.
This is where grabbing an attenuator can really help you out.
These devices can replace your speaker cab while also allowing you to send a signal directly into a recording device, PA system, or USB interface. Some of the nicest attenuators even have headphone outputs for direct monitoring. In this article, I'm rounding up a few amp attenuator reviews based on the following features:
Features Considered
- Can bear the ohm load of tube power amp
- Allow you to run a combo tube amp without the speaker cab
- Allow you to send a balanced (or unbalanced) signal directly from your tube amp into a recording interface
If you're trying to record your tube amp's tone without having to mic it or without having to blast a combo speaker when you need to play quieter, an attenuator will do the job for you.
Here are the four attenuators I'll recommend:
Best Guitar Amp Attenuators (top 4 picks)
ATtenuator | Details | OUR RATING | Browse |
|---|---|---|---|
 | Tone King Ironman II Attenuator | n/a | |
 | Two Notes Torpedo C.A.B. M+ Speaker Simulator | n/a | |
| Rivera RockCrusher Attenuator | 83.2 | |
 | Universal Audio OX Reactive Amp Attenuator | n/a |
Past Entries in this Article (mostly discontinued)
ATtenuator | Details | OUR RATING | Browse |
|---|---|---|---|
 | Rivera MiniRockRec Amp Attenuator | n/a | |
 | Two Notes Torpedo Professional Digital Loadbox | n/a | |
 | Two Notes Torpedo Reload Attenuator | n/a |
1. Rivera Mini RockRec Amp Attenuator
Discontinued, though available in used marketplaces. Section is primarily for reference.
Amp attenuators are generally expensive, which means the Rivera Mini RockRec - at a far lower price point than most - is an attractive option, and easily my favorite loadbox recommendation.
All of the following features are included:
- Balanced DI out (XLR cable)
- Unbalanced TRS out (instrument cable)
- Impedance selector (16, 8, and 4)
- Headphone out for direct monitoring
Here's a look at the connections on the back panel of the Mini RockRec:
Your tube amp connects to the back of the RockRec which then allows you to choose a load impedance (should match that of the power amp rating) and then sends a balanced or unbalanced signal out.
While nicer loadboxes might have more in the way of emulation and cabinet simulators, the RockRec does have six cabinet voicings and covers all the basic i/o functionality. Personally, I'm content to let my tube amp do the heavy tone lifting and rely on less emulation from the loadbox.
In my opinion, this is the best-value attenuator by far, considering cost and value added.
Buy confidently.
IDEAL FOR: Recording tube amps without a speaker cab
CONNECTIONS
95
EMULATION
75
MONITORING
90
COST/VALUE
99
THE PROS
THE CONS
2. Two Notes Torpedo Digital Loadbox
Discontinued, though available in used marketplaces. Section is primarily for reference.
While the Rivera box is a simpler, more straightforward solution, the Torpedo Live by Tow Notes is a stacked, professional grade loadbox that does a lot more than just shoulder your speaker load.
It has all the inputs and outputs you would expect, while also providing a wealth of recording and emulation features, along with an entire software package that you can use to customize everything.
Here's a quick look at what you get:
- 8 different power amps
- 32 cabinet simulations
- MIDI connection
- USB connection
- Onboard EQ
- Headphone out
It's one of the best amp attenuators I could recommend for recording. I also happen to know that the fellow doing Living Room Gear Demos uses this loadbox (or at least has in some of his videos).
The issue that most people will run into is cost.
It hovers around $800 - $900 in most markets, which is more than you might want to spend if you're just looking for a way to quietly practice or record.
If you do want something with the added customization, emulation, and versatility, the Torpedo is a powerful piece of gear that'll do those jobs without cutting any corners. It's also worth noting that it has an extremely low noise floor, making it a good loadbox for handling high gain or heavy tube distortion.
IDEAL FOR: Pro-level recording
CONNECTIONS
96
EMULATION
90
MONITORING
93
COST/VALUE
68
THE PROS
THE CONS
3. Rivera RockCrusher Loadbox
The primary difference between the RockCrusher and the RockRec is the 11-band EQ you get with the RockCrusher. It also has a Studio level option for using a speaker at a lower volume with an extra speaker jack (output) and a main level control in the EQ.
However, it's more expensive than the RockRec, which means your value goes down to an extent.
If you don't really want/need the 11-band EQ and extra recording features, stick with the RockCrusher's younger cousin.
IDEAL FOR: Pro-level recording
CONNECTIONS
92
EMULATION
85
MONITORING
82
COST/VALUE
74
THE PROS
THE CONS
4. Two Notes Torpedo Reload Attenuator
Discontinued, though available in used marketplaces. Section is primarily for reference.
Our second recommendation from Two Notes is the analog offering that goes lighter on emulation options but loads up on additional DI features like a Hi-Z instrument input and re-amping options.
Like the digital Torpedo, the Reload is a fantastic tool to have in the recording studio, as it makes the process of adding a DI and amplified signal together extremely easy.
This is a feature that might appeal to bass players more than electric guitar, but in either case it can be good to have.
IDEAL FOR: Pro-level recording
CONNECTIONS
95
EMULATION
92
MONITORING
72
COST/VALUE
67
THE PROS
THE CONS
Best Options for Combo Amps
Though I've already used combo amps as an example, I wanted to address it specifically since the question seems to come up a lot.
Attenuators are meant to be used with tube amps which would include any combo or tube amp head.
As long as you set it up to go between your amp and speaker it'll do the job and actually works particularly well with combo amps.
Here's a quick summary of the process:
- Amplifier (preamp and power amp) are plugged directly into attenuator
- Attenuator replaces the speaker and handles the ohm load of the amplifier
- Signal can then be routed into an audio interface, PA system, or back into the speaker
The point is to let you play at higher volumes, where tube amps tend to sound better, without having to blast it through your speaker. It's a fantastic tool for any combo amp owner.
How do I match impedance?
The best amp attenuators should have impedance selection, meaning you'll need to know the ohm rating of the speaker output on your amplifier.
Usually it will be one of the following:
- 4 ohms
- 8 ohms
- 16 ohms
In parallel wiring, the math of an ohm load works out like
- Two 16 ohm speakers equals 8 ohms
- Two 8 ohm speakers equals 4 ohms
If you're just going straight from your power amp to your attenuator, it's fine to match the ohms of the existing speaker. In other words, if you're using a tube combo amp and it has an eight-ohm speaker, simply use an 8 ohm setting on your attenuator.
Selectable 16, 8, or 4-ohm impedance setting on the back of the Rivera RockRec.
Most will have a selectable load impedance.
Power Attenuation VS an Amp Mic
The alternative to grabbing an attenuator is to simply mic your amplifier and keep using the speaker cab. In my experience, this is less efficient and doesn't sound as good as the direct connection you get from an attenuator.
Part of the benefit of attenuation is that you can get the tone quality of higher tube amp volumes without the overwhelming volume itself. This is no longer the case when you're simply adding a mic to your amp. Furthermore, it can be hard to get mics to capture the same level of quality that you get from a direct, balanced output.
This is especially true for recording scenarios.
While it's accurate that an amp mic is usually going to be less expensive than an attenuator, it's just not as much of an ideal solution.
If you do decide to mic your guitar amp, one thing I would recommend is an isolation box, like Weezer's Rivers Cuomo uses here:
A mic'd tube amp in an isolation cabinet.
If you go this route, you can see how the expense starts to pile up. A cab like this one and two high quality microphones will probably cost around the same price as a mid to high-end attenuator.
It's up to you, but my personal recommendation would be the attenuator route.
What is an amp power soak?
In the context of electrical attenuation, you might hear the term "power soak." This is simply a technical term given to one of the most common ways that power attenuation works. Power soaking means that all or a portion of the power coming from your amplifier is absorbed by the power attenuator in the signal path.
Will an attenuator damage my amp?
When used properly, a power attenuator poses no danger to your amplifier. Though problems can arise when people use them without reading instructions and understanding how to hook everything up.
Even the high-end attenuators are subject to user error.
To avoid damaging your amp when using an attenuator, I recommend adhering to the following best practices:
- Never, under any circumstances, use a tube amp without a speaker cab or load-bearing attenuator
- Regardless of the attenuator you end up using, always read all the instruction and best-practices documentation provided by the manufacturer
- Always make sure that the ohm load setting on your attenuator matches the ohm load of your speaker output
Understanding the full breadth of best practices will be a situational issue. Make sure you understand the technical properties of your amplifier before you choose an attenuator to compliment it.
Which features matter the most?
The features involved with a guitar amp attenuator are fairly straightforward and include the following:
- Ohm rating or selectable impedance options
- Direct monitoring or headphone outputs
- Balanced and unbalanced outputs (DI out for recording)
Other features like amp emulation, EQ tweaking (at the attenuator level), re-amping, and additional speaker connections would - in my opinion - be considered secondary.
Conclusion
Attenuation is a fantastic tool for guitar players using tube amps. Even if you're happy playing at lower volumes, the ability to record through a balanced direct output is a huge benefit to even the casual musician. I'd recommend prioritizing the crucial i/o features and then letting your amp do most of the tone-related heavy lifting.
If you're more concerned about speaker cab emulation, go with one of the more expensive Two-Notes boxes.
I hope our amp attenuator reviews have been helpful to you in the decision-making process.
Questions about Amp Attenuators
If you have questions about guitar amp attenuators, feel free to leave a note in the comments section below and I'll do my best to help out.
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Written by Bobby on Amps and Roundups
Written by Bobby on Amps and How-tos
Good article, with useful information. But, it appears to be leaning entirely towards the recording features, and is missing the most important reason to review power attenuators, which is how does each given attenuator sound (out of your amp’s speaker) once the attenuator is dialed significantly down? To what degree does it remove highs, presence, articulation, bass response, and most important.. the overall tonal character of the tube amp a person so carefully bought because they like the tone with that amp’s vol on 5-7. Is the given attenuator only very good at getting you from a small hall, to a club. For those of us that don’t play out, that’s not helpful. I’d like to take in a review that compares how each attenuator handles not damaging your tone, with the speaker at ‘loud talking’ volume levels (Living room, wit a handful of people present). So, not apartment bedroom level playing. Double that volume. That.. is the volume I bet 80% of the world’s guitar players want to play at.
Also, Weber Speakers power attenuators are not in the review, which is what I’ve used for 15 years. I’d like to learn how the other attenuators stack up for tone when dialed down.
Thanks
Thanks, Rowan – this is helpful. I’ll look at this for future updates, or perhaps even a second write up.
Hi Bobby
I a fender blues deluxe reissue amp. No phono. Do i need the expensive attenuator or can i use something else? hk redbox?
Thanks! Great article. Greetings from Denmark