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Understanding the Valvetronix EQ and using an external EQ

Here is a compendium of the most frequently asked questions (FAQ), tips and tricks, and common troubleshooting solutions

Moderators: Voxman, laurent_56, Valvetronix Expert Users

Understanding the Valvetronix EQ and using an external EQ

Postby Voxman » 27 Oct 2006, 00:38

(Although written with users of the AD60/120 range in mind, most elements of this post will still be relevant for users of the AD15/30/50/100VT range.)

I constantly read about folk struggling to get good tone with this or that amp model - it's too trebly; it's too bassy; it's too muffled etc etc. So, I hope this FAQ post (with appologies for it's length) is of some help to those of you that might be struggling to find your tone.

As a regular to the various Valvetronix forums, it's become increasingly evident to me that many AD60/120 Valvetronix users do not:

1. Properly understand the nature of these amps...and their physical limitations!
2. Understand and set the on-board EQ properly
3. Appreciate the value of using an external EQ pedal
4. Appreciate the importance of positioning the amp correctly
5. Properly understand 'tube saturation'; the master volume, & the power-attenuator
6. Understand that with 'Gain' (& effects) sometimes less is actually more
7. Think laterally!

1. The nature of the AD60/120's
First thing to understand is that these amps were specifically designed as GIGGING amps, and NOT bedroom practice amps. The internal EQ is geared for the amp models to shine at volume, not at quiet bedroom settings. For those of you who can't sound like Slash, Brian May or (the late) SRV at quieter bedroom volumes, I've got news for you....neither can they!... even with the original gear.

If you compare the Valvetronix amps with say Line 6 gear, you'd be forgiven for thinking that the Line 6 gear sounded fuller & richer at bedroom volumes and in the store. The truth is that the internal EQ has been set that way so it encourages sales...but at gigging volumes its a different story, with the Valvetronix responding like an all-valve amp. And that's the key difference...the Valvetronix sounds better the louder you crank it.

And if you only have an AD60VT/VTX 1x12" speaker combo, don't expect it to sound like a Marshall 4x12 (or even 8x12) stack. The Valvetronix is a compromise...if you want it to sound more like a Marshall 4x12" cab, you need to play it through 4 x 12" speakers - not rocket science, but an obvious fact of life that's often overlooked!

A further limitation of these amps is that in many cases they are only modelling a specific channel of a particular amp and the modelling is based on one variant of that amp. It's also modelled on a 'straight' non-modded version of the amp.

You also need to remember that what you hear on records is often after a lot of complex studio mixing and EQ-ing. Your guitar hero's tone is also most often using an amazingly complex mixture of equipment, stomp boxes, mixers, amps, echo units etc. So, you need to appreciate that as versatile as your Valvetronix is, you can't expect one £800 amp to sound exactly like £30,000 of gear!

So, your idea of what a Marshall JCM800 or Mesa-Boogie dual rectifier sounds like might be quite different to reality. For example, there are so many mods to JCM800's and so many are used with tubescreamers etc that you might not realise just how low gain the original is, or how 'fizzy' a Mesa Boogie can be.

Check out here to listen to some original straight amps, & it will help you appreciate just what a good job Vox has done on the modelling. ... eAmps.html

2. The onboard EQ

Unlike a conventional amp, the V'x amp modelling also models the way the EQ on the 'real' amp works...often with some extra parameters available. It is essential to understand that the EQ works quite differently with each amp model. So, READ THE MANUAL ! - there are lots of good tips on EQ setting in there within the description of each amp model.

For example, on the AC30TB, the Presence is the 'top-boost' control. On some models, the mid/treble/bass are actually interactive eg raising the mids and lowering the treble can actually give a brighter tone; on others the mids and treble may be cumulative, and on others again the EQ works as a 'regular' amp.

With some amp models, e.g. the Marshall's, Recto, and US High Gain (Soldano) just like the real amps these will often sound best with the EQ maxed to give a fuller, richer tone. So if you always set all your EQ at 'noon', you're often going to be disappointed with what you hear! On other models, eg the 1x12" Tweed, maxing the treble but keeping the mids and bass at 9:00 O'clock will often give the right 'twang' typical of that model (with the Presence adding some extra sparkle as needed).

And at gigging volumes, raise those MIDS (see the FAQ on this theme, which explains about the Fletcher Munson effect).

3. Using an external EQ

For those keeping up with the posts here, you'll know that I'm a great advocate of using an external EQ to get the best out of certain models. An external EQ, can be used direct and*/or through the effects loop - but for the EQ to work most effectively particularly on higher gain models it is essential that the EQ unit be placed in the Effects loop. Chrome amps other than the AD100VT/VTH, won't get as good results because these amps have no FX loop.

The reason for this is because in the Valvetronix amps, high-gain amp models have the onboard EQ tone set post gain, whereas low-gain models have the onboard EQ tone controls set pre-gain. Where the external EQ is positioned 'direct' it is not controlling overall EQ for the high gain models, only gain characteristics - which is NOT what is needed by most users.

The amptone article below is not worded as clearly as it might be, but it does try to explain the above. However, when it is talking about using 2 external EQ's (one direct & one through the loop) and using the term 'redundant' for one EQ at any time, this is ONLY from the perspective of affecting GAIN characteristics - it is NOT talking about overall tonal EQ control - & it is THIS which is needed, and why the best results for tonal EQ control on all models is through the loop.

An external EQ provides far wider EQ control than is available from the amp direct. It can tighten up a 'flubby bottom' (read the thread on this theme) and accenuate the top end at the same time. It should be used in addition to (ie not in place of) the onboard EQ, - some folk like to leave it on pretty much all the time (as I tend to do) whilst others use it selectively when needed. But rest assured, it can be like taking a blanket off your amp!

I also now use a BBE Sonic Stomp Maximiser after the EQ in the FX loop, for even better tonal performance, clarity, and a more '3D' sound. It's not an EQ; it works by altering the speed that different frequencies reach your speaker so that the signal is processed more efficiently by your speaker, giving a much clearer, more defined sound.

Reading is no substitute for hearing, so I've prepared a brief clip recorded direct using the line-outs of my AD120VTX. I've used the 'Recto' model (Mesa Boogie Dual Rectifier) because it's notoriously muddy & overly fizzy when used at normal volumes. I used my 1969 Fender Stratocaster which has stock single-coil p/ups because it's harder to get a beefier sound with than my Les Paul. The onboard EQ was completely 'maxed' & the Boss EQ settings were as per the 'flubby bottom' thread. Gain on about 12:00 O'clock first time round, and then 3:00 O'clock. The straight amp tone is first, and then the EQ is kicked in - absolutely nothing else on the guitar or amp is changed.

AD120VTX Recto with & without Boss GE-7 EQ

More recently, I've recorded some You-tube videos. Everything is through my AD120VTX with a Behringer EQ700 stomp EQ in the FX loop, including these 2 vids demonstrating the difference an EQ makes 'before and after': -

If you look on the Roland/Boss site, and the Stomp-box forum, (plus the 'flubby bottom' thread) you'll find details of EQ settings to try out.

The level control on an external EQ confuses some people. It is not a conventional volume/gain control - it accenuates the EQ settings you've selected. So, by raising the level slider although the volume is increasing, you'll also hear a more pronounced affect of the EQ settings you've made (& vice-a-versa)

IMPORTANT: - see update FAQ for details on how to connect a mono EQ to the stereo AD120VT/VTX/VTH Valvetronix amps

4. Amp positioning

If you keep your amp on the floor, you have two problems that will kill your tone: -

A) A lot of your tone (& volume) will simply vanish into the floor, muffling your tone, and
B) Your ears (& those of your audience) won't be hearing your amps frequency range properly. You need to raise the amp up so that sound is being projected at 'ear height'. Ideally, your amp needs to be 3 feet off the floor - but at the very least it needs to be raised a good foot and then angled up.

5. Tube saturation, MV & the power attenuator

By far the largest contributor to giving your tone a more tube like quality is the Master Volume control (which unfortunately is not programmable). If you raise the MV, you'll increase the level of tube saturation (ie the 'amount' of valve power-stage distortion). This is simply a matter of personal taste - for some tones you may want to crank the MV, but for others you may want to wind it down for a cleaner response.

But to get the best & most 'natural' tone from your Valvetronix, ideally you should run it at 60w (or 2x60w on the 120's) ie with the 'throttle' fully open.

However, in real life that's not always practical. So, the V'x amps have a power-attenuator on the back that lets you lower the output power rating, which lets you crank the MV higher (for more tube saturation) whilst keeping listening volumes sensible.

Sure, the power selector is helpful... the 1w (2x1w on the 120's) can be great for playing softly at 1 am in the morning. But just like an all valve-rig run with a power attenuator such as a THD Hotplate you simply CANNOT get the same tone at low volumes with a low power setting. The power-attenuator is a useful tool, but the reality is that it will sap tone to varying degrees. It does not affect tube saturation levels directly though.

The gain is effectively the pre-amp gain, and the normal volume (both gain & normal volume are programmable) allows you to set the patch volume you want to recall relative to other patches. The MV then controls the overall volume but also the overall level of tube saturation. It's a shame that the MV is not programmable - because of this most folk tend to leave it set at a particular level for gigs - eg 2:00 or 3:00 O'clock on the dial is often a popular compromise.

For those of you who are interested in reading more technical articles, this one is particularly good:

6. Gain - less is often more

With the high-gain amp models (especially as you raise the overall volume), if you overdo the gain you can actually muddy your tone and it will become indistinct. A lot does depend though on your guitar and whether you're using an external EQ. Humbuckers will be fatter & darker sounding than lower-powered brighter single-coils. So you may be able to get good results by maxing gain at high volumes with a Strat or Tele, but your tone may muddy with a Les Paul. A lot of this is down to experimentation & experience. The same is exactly true even on the 'originals'. So, drop the gain level down for greater 'clarity' of the distortion you're hearing. And ditto with effects - you need far less reverb/delay etc at louder volumes than you might think.

7. Thinking laterally...

If you're having trouble cutting through the mix with high-gain models, try a different approach with cleaner amp models. For example, try the 2x12 Blackface with gain & MV both on about 3:00pm, and then add Tube O/D or Fat O/D. The Blackface will cut through anything - simply use the EQ (onboard and external if needed) to help give a 'fuller' tone as per your taste.
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