How To Get A Katana To Sound Almost Like A Valve Amp

(Ingredients: a BOSS Katana, a 10-band EQ pedal or 10-band EQ effect in a digital effects board (DEB), guitar of your choice. Has been tested with humbuckers, not yet with single-coils.)

Valve amps have that sound. It pops and snaps, it's clean and clear and as crisp as fresh winter frost.

Which is no-one's description of the sound of a BOSS Katana.

Well, I'm here to tell you how to make a Katana sound like a valve amp. Nearly.

On the 10-band EQ control, add at least 10dB to the 2kHz, 4KHz and 8kHz bands. (Unless you are a bat or a teenager, you will not hear the 16kHz stuff, but change that if you want). I find the 2kHz and 4kHz bands are better at +12.5dB, but your ears may vary. 

The EQ control should be the last one in the chain (except for a compressor). 

Connect the output from the EQ pedal or DEB into the POWER AMP IN socket on the back of the Katana. This by-passes all the pre-amp and effects and sends the signal straight to the power-amp. The only controls that affect the sound are the power selector and the MASTER volume control. Put the power selector to 25W and the MASTER volume at 12:00. Alter to taste later - according to how much oomph your pickups provide.

Turn the guitar volume and tone pots to 7 or so. (I turn the volume up on the  McCarty SE, because the lower the volume pots are set, the less audible the effect of coil-splitting, tone-adjustment, and distortion effects from the HX Effects.)

Strike a note.

It should be whoa, that was sudden, or something similar. It should also sound a whole lot more like a valve amp. 

Tweak the volume on the amp to make it more neighbour-friendly (but not so much the sound hides away in the speakers. I find that happens before 10:00 on the dial.)

What's going on? 

The frequency response curve of a 12-inch Celestion Gold (available on the Celestion website), the kind of speaker used in valve amps, is

 (All their speakers have a broadly similar curve. Actually, so do all guitar speakers.) 

It comes on song around G on the low E-string, is reasonably consistent all the up to the 18th fret of the high E-string, and then has strong(er) area between 2kHz and 5kHz, after which the response drops off a cliff. 

Guitars produce a trail of harmonics, many less than 10 dB down from the base frequency. Reproducing the sound of a guitar properly means making sure those harmonics are amplified equally. Up to 5kHz, the Celestion Gold is giving good treatment to the first, second and third harmonics of all the notes on the guitar, and to at least the fourth harmonics of notes below middle-C (concert pitch - 2nd string 1st fret) - except for the harmonics between and 1kHz - 1.8kHz, where it's a bit soft.

The Katana speaker is not a Celestion. BOSS say it was designed to match the amplifier. My guess is that the Katana speaker remains flat up to 2kHz and then drops about 10dB - 15dB to 5kHz, when it too drops off a cliff, as all guitar speakers will. (Google can't find anything under various variations on "Katana speaker response curve", so BOSS will have to live with my speculations.)

To correct for that slump between 2kHz and 5kHz, we need to boost the frequencies in that range, which is what my suggestion does.

Give it a whirl.

(Edited 6/11/2024)

Recording With The Focusrite Scarlett 2i2 and Helix Effects

Regular readers will remember the problems I, and everyone else with a Katana, had with recording and playback through the thing. I gave up in the end.

I’ve been trying recording on the iPhone / iPad, using the Lexis Audio Editor, which is intuitively easier to use than the iOS Garageband. For my simple mind, anyway. Record with the mic, playback via the Apple dongle and the Katana Aux In. It kinda worked, but not inspiringly.

Then I got the Helix HX Effects. I’ve been playing with it exploring its functionality for a while. I had registered that it treated the SEND and RECEIVE ports as blocks that could be put in the signal chain. I had got as far as using a RECEIVE port / block to receive music from the phone and pass it on to the Katana.

That works because the Helix software lets us create two logical paths (A and B) between the device inputs and outputs. It’s actually easier to see-and-do on the control software than it is to explain (which is how it should be). Put all the guitar-related effects on one path, and use the other path to take the play-along music. Join the paths together at the end, so the play-along music is unaffected by the guitar effects. Works nicely.

One afternoon, I started thinking about recording again. I don’t want to use headphones, and I want to hear the sound of the guitar from the amp. That was always a problem in the past, because I was getting the guitar effects from the amp. Ever since I got the HX Effects, the amp has been set to the Clean channel and all the effects turned off. EQ’s at mid-day. It’s almost tonally transparent.

The following question now makes sense. Can I use a SEND port on the HX Effects to send a copy of the signal to an interface? The interface connects to the laptop via USB and a recording program can use the USB as an input. Also, can I take the audio out from the laptop and plug that in to the Aux In of the Katana. The HX Effects is connected to the Katana via the L/Mono output socket as usual.

I have one signal path from the guitar to HX Effects to the amp; a separate path from the HX Effects to the laptop to the recording software; and another from the recording playback to the amp. So there’s no feedback loop.

And even better… there’s no way background noise can get into the signal chain because there are no microphones!

I’m using Audacity. It’s recording software with some extras, rather than a full-featured DAW, so it will do nicely for my simple mind. I made sure it could record one track while playing back another, which is kinda key to the whole thing. I can.

All I need to be able to do is send one copy of the signal to the L/Mono output, and another copy to a SEND socket. Which is kinda the reverse of bringing in a signal from the RECEIVE port.

I tested everything I could without actually getting the interface. Everything worked the way I needed it to.

Pull the trigger. The interface of choice for the amateur is the Focusrite Scarlett 2i2, which has two inputs: either instrument jack plug or mic three-pin. (Mics need a lot more signal boost than guitars.) I need one short guitar cable (male-to-male jack plugs) to connect the HX Effects SEND to the Scarlett instrument in.

Arrives within 24 hours thanks to Amazon Prime. Took about fifteen minutes to set up, including an online firmware update. Another five minutes to set the recording volume for the guitar.

Now I have to deal with the well-known phenomenon of “recording klutz”, where hitherto fluent playing suddenly misses the beat, because someone turned the red light on. Also with the fact that my playing is, well, not quite metronomic.

Which is why we record ourselves. It’s one thing to know you’re a bit clunky while playing, but another to hear it in playback. It’s so much more embarrassing in playback.

HX Effects - Effects and Sounds

There are a whole load of pedals out there, and some can cost hundreds or even thousands of pounds (Klons). All of them do one of these eight things: 

Drive (Overdrive, Distortion, Fuzz); 

Compressors / Limiters / Noise Gates; 

Reverb / Echo; 

Delay; 

Modulation (Wah, Chorus etc); 

EQ; 

Looper; 

Volume / Effects level control. 

Guitar output and amp Master volume affect the tones, especially the Drive tones.

Even back in the 1960’s, when life was simple and Jim Marshall made you an amp while you waited (well, ok, not quite), studios had a number of effects: reverb, EQ, compressors, filters, as well as a bunch of special effects that the electronic music people had invented. The ultimate piece of electronic music of the 20th century, the Doctor Who theme, was made in a 1960’s sound lab on magnetic tape that was hand-edited.

The processor in the HX Effects can handle up to nine effects (or “blocks”) in one Preset, and has six switches for each pre-set. So I can build an effect out of nine others.

None are compulsory, and some play better with others. A tone based on Drives usually doesn’t work well with anything else except a simple-ish Reverb, but I understand that shoegaze bands started with a metric tonne of distortion and added more effects. So there’s that.

The one effect that hasn’t been transferred to pedals is the resonance that an acoustic guitar has. It’s a mixture of sustain (caused by the momentum of the vibrations of the wood) and reverb (of the sound waves in the hollow body). This is different from the sound of an electric being strummed with the power off, where the resonance comes from the continued vibration of the strings. Take your fingers off the strings on an acoustic and there’s still a lingering sound. Do that on an electric and the sound stops dead.

My unconscious was looking for that acoustic resonance, and I’ve been finding it something like it in combinations of delay and reverb.

Then there’s the most divisive drive pedal there is: the Tube Screamer. Apparently if you use 11’s and a Tube Screamer, you will automatically sound like Stevie Ray Vaughan, but without, you know, the talent. I have 11’s and have tried the Tube Screamer effect, and even allowing for my lack of talent, I still don’t sound like Stevie Ray Vaughan, so there must be something more to it.

Any tone I get under these circumstances is an amp in the room tone, as opposed to guitar in the mix tone. Get a neat tone in-the-room and then use it play along with a backing track: chances are it won’t blend in. At all. For a long time now, the original sound of the instruments has been merely a starting-point for the final sound. If I do get a tone - usually by randomly messing with the pots - that blends in, often it sounds thin and unconvincing in-the-room.

So here’s the pay-off.

In one session recently I was tweaking one of the ready-made presets in the Effects: it had a delay, reverb, chorus, boost and maybe some distortion. I took out the distortion, experimented with the chorus, reverb and delay, and started playing some triads. Twenty minutes later, I stopped.

That’s when I realised what I was really looking for. A sound that makes me want to play more and more. That I can get lost in. Usually that means something ambient-y with delays and reverbs, but it needn’t. So far I’ve found a couple, not counting neck-pickup-clean + a sprinkle of reverb.

HX Effects + Katana Set-Up

I bought an HX Effects at the end of March, from those nice people at GuitarGuitar Camden, where you can buy any guitar you like as long as it’s a Strat and costs £2,000+ (I am exaggerating only slightly. It is cheaper than Denmark Street where the prices start at £2,000 and ascend very quickly.) Since then I haven’t written anything about my endless Tone Journey.

Imagine being dropped in a guitar shop, given the keys to the pedal cabinet and told to play around all your like. That’s what getting an HX Effects is.

I’m playing it through the Katana, (edit: 9/6) using the Instrument In, pre-amp gain at zero, pre-amp volume nearly dimed, Mid-EQ dimed, Treble and Bass at 12:00. The power amp is set at “0.5W” (/edit) and I control the output with the Master volume.

I’m playing mostly between 65-75 dBA, and have made the following very important adjustment to the amp positioning.

I sit on a barstool about two metres away, on a chair about a meter away, depending on whether I’m using the HX Edit program.

Brief acoustics digression. When the wavelength of a note is less than the diameter of the speaker, that note and those above it will start to “beam” out of the speaker. For a 12” speaker, that frequency is around 1100 Hz, which is about the highest note on the guitar. BUT, guitar strings produce a lot of overtones - fifths and octaves - which are not a lot quieter than the fundamental tone - so that playing A440 produces second harmonics of 1,760 Hz, which will go out like a lightbeam from a big speaker (okay, there are lobes to the side, but only if you’re doing a science degree). Stand to one side or above the speaker and those higher harmonics will pass you right by: the sound will be smoother and lack bite. What I heard over at my friend’s place, where we sit with our heads at speaker level, were all those higher harmonics, which gave the impression of bite and air. This is why mic-ing speakers is more of an art than it should be: where you put the mic affects what exact mix of overtones and bass notes you get.

Chasing tone is to acoustics what cooking is to chemistry: there’s a science underneath it, but mostly it’s applied magic.

The towel under the front of the speaker means I get the overtones beamed at me, so I hear a sound with more air and snap than I would if the speaker was pointing parallel to the floor. This makes a BIG difference to my appreciation of the “tones” I’m setting up on the HX Effects.

I have one Preset with nothing in it, to send the guitar output unchanged to the amp, but despite that the sound through the HX Effects sounds a little tighter and snappier. I’m assuming that the ADC-in / DAC-out conversion, plus any other system circuitry in this “empty path” through the HX Effects, creates some compression. I’m not complaining. It has given me back the neck pickup, which sounded too snarly and nasal through the Katana.

Okay… set-up over. Actual tone-chasing next.