Studio Diary #31: Attenuators Colour The Sound

Attenuators are one of the reasons we can enjoy valve amps at home without upsetting the neighbours. I’ve never really thought about how they affect the overall tone … until now.

In this blog post, I’m going to look at the two attenuators that I have – the Two Notes Captor and the Fryette PS-100 Power Station – and work out what they sound like. And I’m including some sound samples, so that you can hear the differences for yourself.

tl;dr

I’ve got two attenuators / load boxes: the Two Notes Captor and Fryette PS-100 Power Station. Using either of them changes the overall sound. This is a combination of the attenuator and/or changes from turning the amp up.

Sound samples are included, so that you can hear the differences for yourself, and draw your own conclusions.

Table of Contents

• tl;dr
• Why Am I Doing This?
• A Quick Recap
  • What Is An Attenuator?
  • What Is A Loadbox?
  • Is The Captor An Attenuator Or A Loadbox?
• How I’ve Used The Two Notes Captor
  • My Regular Signal Chain
  • When I Need More Control Over The Attenuation
• How Does Each Attenuator Colour The Sound?
  • Methodology
  • No Attenuation
  • Two Notes Captor, -20db Attenuation
  • Fryette PS-100 Power Station, Volume Matched To The -20db Attenuation
  • Fryette Power Station Into Two Notes Captor
• What Have I Learned?
  • Everything Has A Sound
  • Attenuating Your Amp Is Going To Change The Final Sound
  • What Matters Is The Final Sound
• Are You Done With The Two Notes Captor?
• Final Thoughts

Why Am I Doing This?

It all started when I listened to this video:

In the video, John from the Sonic Drive Studio YouTube channel compares two load boxes in a straight A/B test: Fractal Audio’s LB-2 and Two Notes’ Torpedo Captor X. He demonstrates how each unit has its own sound; the LB-2 is more mid-scooped with more low-end, while the Captor X is more direct and mid-focused.

And that got me thinking.

While I don’t own the Captor X, I do have several of the original Captor units here, and I use them all the time. How does the Captor sound, compared to the Fryette PS-100 Power Station?

I realised that I have no idea. Kinda feel like I should, really.

A Quick Recap

For several years, the Two Notes Captor has been an essential part of my signal chain.

The Captor was the first reactive attenuator and load box to become affordable for home users like us. It was a complete game changer. Thanks to the Captor, we can enjoy valve amps either at home volumes, or as part of a completely silent recording setup.

What Is An Attenuator?

Valve amps sound much better when you turn them up. That allows the valves to go from simply amplifying your guitar to also adding harmonics, distortion and compression in a way that improves the overall tone. Unfortunately, a cranked valve amp is just too loud for use at home, and that’s where an attenuator comes in.

An attenuator is a device that allows us to turn down the overall volume of our amps. It sits between the amp’s speaker out and your speaker cab, and essentially it converts power into heat.

The best attenuators are called ‘reactive’: their circuitry is designed to mimic the electrical behaviour of a speaker. That’s important because it influences the way your amp’s output transformer responds, helping it act closer to the way it does when your speaker cab is plugged directly into your amp. In turn, this helps your amp sound and feel like you don’t have an attenuator plugged in at all – just quieter.

What Is A Loadbox?

A loadbox is an attenuator that you don’t need to plug a real speaker into at all.

They’re used for silent recording, where you take a signal from the loadbox, and then apply some sort of speaker emulation (normally an impulse response) later on.

Is The Captor An Attenuator Or A Loadbox?

The original Two Notes Captor is both an attenuator and a loadbox.

• You can use it as a -20 db attenuator.
• You can also have no speaker plugged into it at all, and use it as a pure loadbox.

When you use it as a loadbox, you can take a signal out of the Captor into your DAW, and then apply an impulse response to mimic the sound of a speaker cab. Or, you can do what I sometimes do, and stick a Two Notes CAB M+ between the amp and the Captor, and run your impulse responses there.

How I’ve Used The Two Notes Captor

My Regular Signal Chain

When I’m just playing guitar in the room (for fun, or when I’m trying out a new pedal), my signal chain always looks like this:

The Two Notes Captor sits between whatever amp I’m using and my speaker cabs, and I’ve always got the speaker cabs plugged into the -20db output on the back of the Captor.

I’m not just doing this for the attenuation, though.

Often, I’m using the Captor effectively as a junction box, so that I don’t have to find a longer speaker cable to go from my amp. If you’ve got more than one amp, it’s a really convenient way to easily switch between amps: just power one amp down, unplug it from the Captor, and then plug the next amp into the Captor instead.

So much so, that I’d forgotten that I was doing this 🤦‍♂️

When I Need More Control Over The Attenuation

Last year, I got a Fryette PS-100 Power Station attenuator & loadbox for my Tweed Deluxe amp. Where the Captor has a fixed -20db of attenuation, the Fryette Power Station (effectively) offers variable attenuation. It’s very useful for amps that don’t have a master volume (like the Tweed Deluxe), and for amps that sound best when properly cranked (like the Marshall Origin 20H).

When I use the Fryette Power Station, my signal chain now looks like this:

That isn’t a copy & paste mistake on the diagram.. I’ve been using two attenuators at the same time without realising it 🤦‍♂️

Coming back to the video … it was only when I sat down to cable everything up for a A/B test between the Fryette Power Station and the Two Notes Captor that I discovered what I’d been doing for the best part of a year.

Did it matter? Just how transparent is each attenuator? And what difference does it make when they’re chained together?

How Does Each Attenuator Colour The Sound?

Methodology

As the Two Notes Captor has only one setting – a reduction of -20db – that’s where I started.

• I plugged my speaker cabs into the -20db output of the Two Notes Captor.
• I set my amp to give me a comfortable home volume.

When I switched over to the Fryette PS-100 Power Station,

• I plugged my speaker cabs into the output of the Power Station.
• I adjusted the Power Station volume control to match the volume I’d had through the Captor.
• I did not change any settings on the amp.

For the guitar amp, I’m using my Synergy rig (Synergy SYN-1 enclosure + SYN-5050 power amp). I’ve gone with the Synergy OS module because it’s very revealing about changes to the mid-range. (Or, if you prefer, it’s less forgiving about the mid-range being messed with 🙂)

I mic’d up both cabs, so that we can hear the differences. The only processing I’ve done to the recordings is to try and normalise the volume levels in post, so that we’re not fooled into thinking one recording sounds better because it’s a bit louder. I’ve also kept a little before & after on each recording so that we can hear what noise each attenuator adds to the overall signal too.

Nothing was re-amped; I did a separate performance for each setup. Yes, there’s some variation in my playing as a result, but that also reflects how my playing changed because each setup sounded different. I think that’s important, and often overlooked. Many of us home tone players are confidence players, and the sound we hear out of our speakers affects how we play.

I’m listening back on both studio monitors and headphones. Some of the sounds I’m about to describe are far more noticeable through my studio monitors than through headphones.

No Attenuation

Let’s start with the sound of the amp with no attenuator at all. This is my reference sound that I’ll use to try and hear how each attenuator is colouring the tone.

To my ears, I’m hearing:

• a solid low-end: it’s not boomy, it’s just right for the higher notes to sit on top of
• a very chimey top-end, especially around the 0:40 mark: the top strings are ringing out nicely
• it’s quite squashy overall: the pick noise is coming through in a very plastic-sounding way

Apparently, this is the Dumble sound 🤷‍♂️

It’s a good representation of what I hear in the room directly through my speaker cabs. My cabs are open-backed 1×12’s, so the tone does fill the room in a way that isn’t captured by close-mic’ing the cabs. I think it’s close enough for this post.

For good measure, this is what the passthru output on the Two Notes Captor sounds like:

If the Captor’s passthru output colours the sound, I can’t hear it.

That’s good news: it means I can still use the Captor as a convenient way to chain speaker cables together, as long as I make sure that I’m using the passthru port.

Two Notes Captor, -20db Attenuation

Here’s a performance with the speaker cabs plugged into the -20db output of the Two Notes Captor:

Here’s what I’m hearing:

• there’s a low ‘thud’ that wasn’t there in the Direct recording above; extra low-end percussion when I’m palm-muting
• the top-end has lost a little bit of the chime, like it’s been rounded off a little

How much of this is the Captor, and how much of this is the power amp because I’ve had to turn the amp up to compensate for the attenuation? I don’t have the experience to know.

Fryette PS-100 Power Station, Volume Matched To The -20db Attenuation

Here’s a performance of the speaker cabs plugged into the Fryette PS-100 Power Station. I adjusted the volume on the Power Station to try and match the volume I got when I was using the -20db output on the Captor:

Here’s what I’m hearing:

• this recording does not have the low ‘thud’ that was present in the Captor -20db recording
• the top-end has lost more of the chime than the Captor did
• the recording is a lot more mid-forward than any of the others so far
• gotta love that transformer hum from the PS-100!

For comparison, here’s the original Direct recording again:

Hearing them back to back, the difference in the prominence of the mid-range is quite stark. I don’t think the mid-range itself has changed; I think it’s more that the Power Station has lost some of the top end and low end from the signal, which has brought the mid-range more forward to my ears.

And that hum … it’s clearly audible even while playing 🙁

Don’t take this as the definitive example of what the Fryette Power Station sounds like.

The Power Station has switches on the front for changing the sound of the attenuator. I recorded these using the ‘flat’ settings for the attenuator circuit, with both the Presence and Depth controls around the 4 o’clock mark.

In a home situation, all your gear is going to be in the one room: amps, cabs and the Power Station. I’ve found that makes it a little hard to hear whether or not I’ve found the right settings on the Power Station to match the direct amp. In the room, the differences are more subtle than in the final recording.

And, to be honest, I’m not even sure it’s possible to get a perfect match. Hold that thought; I’ll come back to it shortly. Before I do, there’s one last recording to share, and it’s the whole reason I started this blog post.

Fryette Power Station Into Two Notes Captor

To finish off, here’s a recording that uses the signal chain I’ve been using for most of the last year without meaning to: the Fryette PS-100 Power Station into the Two Notes Captor, with my speaker cabs plugged into the Captor’s -20db output:

What I’m hearing is very interesting:

• Even after normalisation, this sounds louder than the other recordings. That’s going to affect our perception.
• It sounds like the treble or upper-mids have been boosted, giving it a more vintage vibe to the slightly mid-scooped original Direct recording.
• There’s more energy in the low-end compared to the Fryette alone, but it doesn’t have the thud that going through the Captor alone had.

Once again … it’s the same guitar, same amp settings, and same attenuator settings as before. All I’ve done is changed the signal path so that both attenuators are active, and then turned up the Volume on the PS-100 to compensate.

What Have I Learned?

Everything Has A Sound

Every piece of gear in your signal path colours the sound in some way or other, and that most definitely includes our choice of attenuator.

Unfortunately, it doesn’t seem to be possible to create an attenuator that’s 100% accurate. As best as I understand it, the reactive circuit emulates the impedance curve of a speaker, so that the power amp reacts as-if it is ending power out to a real speaker.

Thing is, it’s not emulating your speaker’s impedance curve. The power amp isn’t directly connected to your speaker. The impedance curve was baked into the attenuator when the unit was designed.

As a result, there’s always going to be some mismatch between the direct (non-attenuated) sound, and the attenuated sound. I suspect that the more esoteric your choice of speaker, the larger that mismatch will be.

And that’s before we consider the effect of things like the Fletcher-Munson curve.

Attenuating Your Amp Is Going To Change The Final Sound

It isn’t just the attenuator that’s changing the signal. To get a loud signal that needs attenuating, I have to change my amp settings.

Guitar amps aren’t hi-fi clean amplifiers. That’s why we like them so much. The sound changes as we turn them up. In particular, power amps can start to add compression, and can also start to shave off some of the top-end.

That’s not always a bad thing. Overdriven and distorted tones can often benefit from the treble frequencies being rounded off, for example.

But for cleaner tones, or anywhere really where you want to capture a wide frequency response, you might be better off avoiding an attenuator altogether if you can.

What Matters Is The Final Sound

Your attenuator isn’t a standalone piece of gear. It doesn’t make sound on its own. It influences the overall sound that you produce. Don’t think of the attenuator as a much-needed volume control. Think of it as a tone machine in its own right, and you’ll find ways to treat the attenuator as a positive part of your overall sound.

And, at the end of the day, that’s what matters: the sound that comes out of your speaker cabs or the sound that you capture in a recording.

Are You Done With The Two Notes Captor?

No, I’m not.

Although I’ve got some lovely amps, I don’t use them that much. I tend to dig them out for special occasions. Most of the time I’m just playing pedals through my Marshall DSL 20HR. No particular reason, it’s just what makes me happy.

Since I started using it, I’ve always run the Marshall DSL 20HR through the -20db output of the Two Notes Captor, and I’ve been really happy with how those two sound together. My pedals have never sounded better.

As part of the prep for this blog post, I did move things around in here so that the Fryette Power Station is now next to all the amps. I can finally run the Marshall DSL 20HR through the Power Station to hear how that sounds. I will do this, out of curiosity, but I can’t see it being a permanent arrangement.

At the end of the day, the Power Station is a full-blown valve amp that happily guzzles 350W of extra power. That’s on top of the power that the Marshall is using. The Two Notes Captor is completely passive; it doesn’t draw any additional power at all. It makes a lot of sense to continue to use the Captor where possible, and limit the Power Station to those situations where it’s the only choice.

Final Thoughts

This was a day very well spent.

Tess and I are about to sit down and put regular time into recording our music; our first session is this coming Thursday. Inevitably, there’s going to be a lot of guitar in those recordings. Live, we’re an acoustic band (1 guitar + 1 vocals); for recording, we’ve decided to explore incorporate electric guitar too. The investigation I’ve done for this blog post is going to help me get closer to the sound that we want to capture.

I’ve also learned how to get a sound out of the Synergy OS module that I really like (hint: record a direct sound!) When I first got it, I really didn’t like what I heard. After changing my signal path for this testing, I’m really digging it. There’s a good chance that I’m going to use the Synergy OS module on the recordings that I’ve mentioned above. I’ll write up a very belated First Impressions shortly.

I’m also very pleased with the first attempts at recording my speaker cabs using microphones. I’ve fallen out of love with impulse responses recently, which was frustrating me a lot. Expect a blog post on this soon too.