Studio Diary #18: Recreating The Sound Of My Speaker Cabs Using Celestion Impulse Responses

Now that I’ve added the Two Notes Torpedo CAB M to my setup, the next challenge is to set it up to sound like my actual speaker cabs do.

One day, I want to make my own impulse responses of my speaker cabs. I want to be able to share them with you, so that you can recreate the signal chain I use for yourself. That’s something I can’t do with any impulse responses that I buy.

I’m going to be using Celestion’s official impulse responses on the CAB M, until I can replace them with my own impulse responses.

What Am I Trying To Achieve?

Have you ever watched or listened to a pedal demo, and found it didn’t help because it was made using gear you don’t have and can’t get?

I want to avoid that.

I want to make sound clips using common gear, and I want those clips to sound as close as possible to what you’d hear if you ran the pedal into the same amp yourself.

That, and I really like the sound of my rig, and I want to capture that sound for recording my own original music.

Being Realistic

There are practical limits on how close I can get the recorded sound to match the in-the-room sound.

The microphones used to record impulse responses colour the sound. Many folks who make impulse responses use preamps and channel strip effects to make their IRs “mix ready”.

And I’m using open-back cabs that are up against the wall of an untreated room. There’s a bass response in the room that isn’t going to reproduced on a professionally-made IR.

Why Use Impulse Responses From Celestion?

I’ve got a collection of 1×12 open-back cabs made by Victory Amps, and all of them are fitted with speakers made by Celestion:

  • 15 ohm Celestion Blue
  • 16 ohm Celestion A-Type
  • 16 ohm Celestion G12M-65 Creamback
  • 16 ohm Celestion V30

My Blackstar Studio 10 6L6 is a combo amp, and it’s got the stock 16 ohm Celestion Seventy80 speaker in it.

Celestion don’t just make speakers any more. They’ve been making really high-quality impulse responses of their speakers in various generic cabs for a few years now.

What Are The Trade-offs?

Unless I’ve missed it, Celestion doesn’t say whether or not their impulse responses are of 8 ohm or 16 ohm speakers. They also don’t document the cabs that they put these speakers in.

The end result? Celestion’s IRs won’t sound identical to the speakers and cabs that I have.

The second trade-off is that Celestion doesn’t publish a comprehensive library of IRs for each speaker and cab. They don’t publish details of microphone placement (distance from the cab, position relative to the dust cap or cone). Instead, they publish IRs labelled by ‘tone’, such as ‘bright’, ‘balanced’, ‘dark’, ‘dark 2’ and ‘fat’.

I’m not a fan of that. I’d much rather have a larger library of IRs so that I’ve got control over the microphone placement. It makes it a lot easier to pair two IRs together, in my experience.

As well as IRs made using single microphones, each speaker/cab IR library also includes some captures made using a blend of two microphones. And there’s some rear-of-cab and room mic captures too.

How Do You Buy Celestion IRs?

I’ve just been going to their website, and buying their impulse responses in bundles of 5 as and when I’ve needed them.

You pick which cab types (1×12, 2×12, 4×12, etc etc) and speaker types you want, and add them to the bundle. When all the slots in the bundle are full, there’s an “Add To Cart” button at the very bottom of the web page.

At the time of writing, you can only buy one IR bundle at a time. If you want to buy IRs for ten different cab/speakers, you need to buy the first bundle, and then go back to choose your second bundle.

When you complete the checkout, you don’t get an automatic download or a download button on the screen. Go to the “My Account” page, and there’s a Download option on the left hand side of the screen.

Your purchases don’t always appear immediately. The bundle I bought this evening took about half an hour to appear in the Downloads section.

What Am I Using?

In real life, I’m always running two cabs at one, wired in parallel. The cab with the A-Type speaker is always on, and I pair it with either the Celestion Blue or the Creamback depending on the amp I’m using. (I never use the V30. I’m not a fan.)

Best way I can describe it, the Celestion Blue or the Creamback defines the character of the sound. The A-Type is a quieter speaker, and it adds weight or body to the sound without overpowering the other speaker.

It’s a setup that I’ve grown to really like.

On the Two Notes Torpedo CAB M, I’m running two IRs at a time in each preset. One IR is of the Celestion Blue or Creamback at 0db volume, and the other IR is of the Celestion A-Type at -9db or -12db to taste.

After a bit of experimenting, I’ve settled on Celestion’s combined ‘Low Gain’ SM57 / Royer R121 IRs for each speaker. They’re not quite right – they’re both adding something that my cabs don’t, and they’re missing something that we hear in the room – but they’re the closest I can get. And they do sound good. Really good.

I’ve tried both the 1×12 open cab IRs and the 1×12 closed back IRs, and so far I much prefer the open cab IRs. The closed back ones feel stiff to play through and sound a little darker.

I’ve made some presets with the A-Type IR from the closed back IR library, just in case they prove useful. With the CAB M, it’s easier to make the preset first and then test it later!

Building The Collection

I’ve got my core tones (Celestion Blue / A-Type, and Creamback / A-Type) sorted. The only other physical speakers I could really do with would be a pair of really good Greenbacks (a 75 Hz and a 55 Hz for classic Marshall and Vox tones). I don’t have anywhere to put the cabs though!

It’s much cheaper – and much easier – to get more IRs instead. At the moment, a bundle of 5 speaker cabs costs less than £30 GBP. The real speakers and cabs would cost close to £2000 GBP. And I still wouldn’t have anywhere to put them.

I’m planning on getting all of Celestion’s 1×12 open-back cab IRs eventually.

Why am I getting them? Curiosity, mostly. I want to find out what they sound like, what they can offer. Maybe there’ll be times where I prefer them to my core tones.

I’ll never know if I don’t get them.

Footnote: V30 / V-Type Speakers

I do have a good reason to get the Celestion IRs of V30s and V-Type speakers in 1×12 cabs. For some unknown reason (I’m really not a fan!), amp manufacturers keep using these speakers in their products.

I think it’d be nice to record demo clips using these speakers, just to give my audience the chance to hear the difference between V30s, V-Types, and something much nicer.

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