The Big Guitar Amp Sim Roundup + Review

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Dewdman42
KVRAF
1736 posts since 14 Mar, 2006

Post Mon Oct 14, 2019 5:49 pm

hi-z is the impedance. You are getting close by using that input for sure. A lot of people aren't using hi-Z at all, so they are way off already and need some kind of DI box and don't even know it.

with the AXEIO, the hi-Z input is adjustable and I personally I am notice an incredible improvement in sound over other hi-Z direct boxes I have used in the past.

Yes it matters... "AI" has nothing to do with it. How your guitar responds in the pickups will matter depending on the the way it interacts with the input on your audio device...impedance matching is very very important.
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audiojunkie
KVRAF
2917 posts since 19 Apr, 2002 from Utah

Re: The Big Guitar Amp Sim Roundup + Review

Post Mon Oct 14, 2019 6:03 pm

Dewdman42 wrote:
Mon Oct 14, 2019 3:37 pm
The point Craig is making is that when you go too hot into the A/D converter, you get bad digital clipping. And he feels that the meters are too slow to realize you may be getting some fast attack clipping prior to hitting the A/D converter. Perhaps.

Generally its true you want your level fairly optimized without clipping the A/D converter. So you can either just set the level conservatively or use some kind of analog limiter in front of the A/D which lets you feed it a little hotter and not worry about digital clipping, which his little cable hack does in some fashion, though myself I prefer to just get the level right and preserve the dynamics. But it would be interesting to build one of those sometime to see how it sounds.

The AXEIO has its own physical LED meter on the front of the unit which already gives me a pretty good idea whether I'm hitting the red or not before the A/D, and a gain knob to adjust it a little lower.

With 24bit encoding and 32bit processing inside the computer...there is a lot of room to handle stuff. Recording digital is not the same as recording analog where you need to get the signal as hot as possible without clipping. In those days we had to worry a lot more about tape hiss and other stuff. In digital the noise floor is so low, that you can generally just be a little more conservative with your gain setting to avoid digital clipping during A/D.

A nice natural analog compression before the A/D is not really such a bad thing...depending on what you're recording, but i just don't think its a necessity and I'd rather get all the dynamics from my guitar into the recording.
That makes sense--what you are saying. However, I wonder if that's really what Craig is saying, otherwise, wouldn't a software brickwall limiter do just as well to prevent the clipping? I gathered that there was a particular reason he chose the hardware route--chiefly to attenuate the initial transients. That's why I'm trying to understand why Craig chose a hardware route over an obviously more simple software VST route. :-)
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Dewdman42
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1736 posts since 14 Mar, 2006

Re: The Big Guitar Amp Sim Roundup + Review

Post Mon Oct 14, 2019 6:05 pm

no a software limiter happens AFTER A/D conversion. So if you digitally clip at the converter its too late.
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reggie1979
KVRAF
1879 posts since 26 Nov, 2018

Re: The Big Guitar Amp Sim Roundup + Review

Post Mon Oct 14, 2019 6:15 pm

Too late, folks it's too late.

Ummm, sorry, what were we talking about?

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Anderton
KVR Expert
140 posts since 4 Mar, 2004
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Re: The Big Guitar Amp Sim Roundup + Review

Post Mon Oct 14, 2019 11:07 pm

Mats Eriksson wrote:
Mon Oct 14, 2019 1:22 pm
For what is worth I think in order to make any interface cope with transients, initial peaks, you have to use lke 256 Khz sample rate at at least 128 DB headroom, for a short period of time.

And no, the dynamics of an electric guitar with magnetic pickup is not that extreme.
Then why do you say you need a 128 dB range?

The following image of a plucked guitar string speaks for itself. It is normalized to 0, which shows you just how strong the transient is compared to the average level.

Image
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Anderton
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140 posts since 4 Mar, 2004
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Re: The Big Guitar Amp Sim Roundup + Review

Post Mon Oct 14, 2019 11:09 pm

Dewdman42 wrote:
Mon Oct 14, 2019 11:42 am
craig, thanks for all the reviews. One suggestion would be to update your first post at the top of the thread with a link to each of the specific reviews that you wrote on each one.
Good idea. I'm doing the last review (a scoop - a preview of the next ReValver!) after TH-U, and then I'll add the links.
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Anderton
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140 posts since 4 Mar, 2004
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Re: The Big Guitar Amp Sim Roundup + Review

Post Mon Oct 14, 2019 11:14 pm

Dewdman42 wrote:
Mon Oct 14, 2019 3:10 pm
I personally don't think I would like having passive compressor built into my guitar cable, but never having tried it...maybe I'd love it!
I loved a review I read of the Les Paul Standard where the writer said he tried the transient control, but he couldn't hear any difference. That's exactly the point! You're not supposed to hear a difference, you're just supposed to be able to get a higher average level into your interface for a better signal-to-noise ratio, more predictable compression action, etc. The guitar sounds the same, because the transient that gets whacked is so fast your ear has a hard time registering it anyway.

Also technically speaking, it's not a compressor, it's a limiter. And because you can build it into a cable, it's not necessary to mod the guitar.
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Anderton
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140 posts since 4 Mar, 2004
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Re: The Big Guitar Amp Sim Roundup + Review

Post Mon Oct 14, 2019 11:32 pm

Overloud TH-U

Some amp sims products have specific goals, like the PRS SuperModels, STL Tones Tonality, or S-Gear 2. Others, like AmpliTube, Guitar Rig, Helix, or Axiom include a huge complement of components. They’re like your virtual pedalboard—or perhaps more accurately, like your virtual pedalboard if you had an unlimited budget and lots of space.

TH-U weighs in with 89 guitar amps and 50 guitar cabs, 4 bass amps and 2 bass cabs, 77 stompbox effects, 18 microphones (up to 4 on each cabinet), the ability to load two impulses, a looper, and over 1,000 custom presets. In addition to Overloud’s amp, there are “official” versions of Randall, Brunetti, DVmark, and THD amps.

For some amps, TH-U takes a page from Peavey ReValver, BIAS Amp, MOTU’s amp sims bundled in Digital Performer (which are surprisingly good), and others by providing the option to switch out different tubes (Fig. 1). There’s even a virtual Variac, which has the benefit of not being able to physically fry your amp if you set it incorrectly! There’s also plenty of MIDI control, with MIDI Learn. In addition, the TH-U Rig Player captures the sounds of specific rigs and seems somewhat Kemper-like. These are available as expansion packs; I tried out the American, British, and Vintage packs, and found them impressive.

Image

Figure 1: The Amp Tweaks section is where you can tubes, and dial in the virtual Variac setting.

Of course, this begs the question of whether Overloud includes all this stuff just to dazzle people and win the “amp sim arms race.” I take a different viewpoint. We all know reactions to amp sims are very subjective, so the more options there are, the more likely you’ll find sounds you like. I don’t think any company expects you to use everything they provide—a jazz player is unlikely to use a high-gain/metal amp. But they do hope you’ll find enough sounds you do like to want to purchase their software. Given that these “everything for everybody” sims tend to be pricier, value received is proportional to how many of the amps and effects you’ll use in your music, and how much you like the amps you do use.

THE HISTORY LESSON

Full disclosure: I was not a big fan of TH2. The only way I could get the sounds I wanted was by adding other effects (mostly EQ) before and after it. I thought their ReSPiRe cab technology, which was intended to simulate the sound of being in front of a physical amp, wasn't very effective. There were elements that had potential, like the splitter for doing bi-amp effects, and some of the effects were really quite tasty. It wasn’t so much that TH2 was bad; I just had better options.

Then Cakewalk added a lite version of TH3 to Sonar, which was my primary DAW at the time. There was a definite sonic improvement. The only issue was that while most TH2 presets could translate to TH3, some simply couldn’t. Then again, sometimes you have to give up the past for a better future, and TH3 was definitely a better future...so of course, I was curious if TH-U was going to be another leap forward, or an incremental improvement. Maybe at this point you’re curious too, so let’s fire it up.

THE PRESETS

So here’s the deal about the presets: there are a zillion of them.

Image

A preset, in all its glory. You can zoom out or in (and scroll along the effects chain) on the main window with the components, but I prefer to use the small navigator windows at the bottom to cut down on clicking and scrolling.

As I flipped through the presets, they fell into three categories: “I would never use this preset again,” “I would definitely use this preset again,” and “I can tweak this preset into something I’d use again.” Many of the higher-gain presets have that “fizz” I’ve alluded to in most other sims, but it’s easy to get rid of it: add the parametric EQ afterward, cut the gain back in Peak mode, set Q to maximum sharpness, then vary the frequency until the fizz goes away. If this makes the sound seem not as bright, use the EQ’s second stage to add a bit of a high-end boost with the shelf mode. It’s amazing how many times I could take a preset from “no” to “yes!” with this simple technique.

The ReSPiRe cab option was a big surprise. Overloud builds it into a lot of their presets, and with either TH2 or TH3, the first thing I did was bypass it. But in TH-U, it’s far more effective, subtle, and realistic. When creating presets from scratch, I leave it in almost all the time.

By far, I got the most out of TH-U when creating my own presets. That’s not surprising, because I’m pretty picky about sound. But the takeaway here is I could get the sound I wanted. The “construction kit” nature of TH-U justifies including all those amps, cabs, and effects. The sound you want is in there somewhere...you just need to find it. Because there’s no “Favorites” feature or tagged database, I highly recommend creating some custom banks so that when you either find, create, or tweak a preset into something you like, you can save it.

TH-U’s "character" is also worth mentioning. There’s a certain “raw” quality I find appealing, almost like it’s pushing the amp. There’s some girth to the sounds; sure, it’s possible to get thin sounds if you want, but that’s not TH-U’s default state. This also spills over into the clean sounds, which I like a lot. Yes, they’re still clean, but they have a certain authority that’s missing in some amp sims. As to effects, they’re uniformly useful. The reverbs are excellent, but then again, Overloud’s Breverb is outstanding. I assume they’re using a derivation in TH-U.

Finally, the Rig Player add-ons are solid. The basic ones with under 100 rigs cost 19 Euros each, which converted into American money, is four coffees at Starbucks (or $19 if that’s how you calculate exchange rates). Expansion packs with over 100 rigs cost $29...still reasonable. The rigs and Rig Player do add something to the party, and make TH-U a bit more of a “platform” that’s capable of expansion.

THE BOTTOM LINE

Sims on this level aren’t an "impulse price" item, and like other sims, you can go down a rabbit hole of expansion packs. So is it for you? As with other sims, you can download a demo, and decide for yourself. I suspect reactions would be polarized—some will love it, some not. I think a lot of that depends on whether you’re interested mostly in presets, which at least in my opinion are hit-or-miss, or prefer to construct your own sounds. For construction fans, there’s more than enough here to give you what you need. And if you have other amp sims, the character is sufficiently different that you’ll get sounds that aren’t exactly like other sims. I like the vibe, even though it’s quite different from my usual “CGI guitar” sounds. Sometimes I just want a bluesy, nasty sound so I can pull out my (magnesium) slide and wail, or a big—but clean—Fenderish sound to fill out a track. But of course, TH-U does more than that.

I doubt anyone will use everything that’s available in TH-U, but that’s not really the point—because every guitarist will probably have their own favorites out of the collection, which won’t be the same as other guitarists. Overall, TH-U is ambitious, sprawling, and comprehensive. I’ll be filling up the “Craig’s Faves” banks with quite a few presets in the months ahead.
My educational website has launched! Read articles, see videos, read reviews, and more at https://craiganderton.org. Check out my music at YouTube.com/thecraiganderton, and visit my digital storefront at https://craiganderton.com. Thanks!

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Anderton
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140 posts since 4 Mar, 2004
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Re: The Big Guitar Amp Sim Roundup + Review

Post Mon Oct 14, 2019 11:48 pm

audiojunkie wrote:
Mon Oct 14, 2019 3:27 pm
So, what would be the difference between using a physical/hardware limiter prior to I/O hardware vs putting a software limiter (from within the I/O hardware--like a brickwall limiter vst)? Would it be intent or what one is trying to achieve?
Anything in the software is post-A/D converter, so it doesn't solve the problem of sending spiky transients into the A/D converter....which requires you to turn down the input level, and thus sacrifice input level. But there's much more to the story than that:

* The LED has no overshoot, nobreathing, and nopumping. No active electronic circuit based on gain control can do that.
* The reaction time is instantaneous, so there's no need for look-ahead. The circuit lives in real time.
* The LED has junction capacitance, which increases with voltage. So the more level you put into it, the more capacitance there is (figure about 70 pF max, although that’s not an exact science). This not only shaves off the top, but does soft-, not hard-, clipping above the frequency of the guitar (i.e., where the spikes live).
* You can select an LED with a breakdown voltage to match your pickups. This is why the Gibson circuit worked so well - the pickups levels were a known entity. Luthier Jim DeCola went through a bunch of LEDs to find ones with the ideal breakdown voltage to shave off only the peaks. This is also why you have to use red LEDs. Other colors have too high a breakdown voltage.

Anyone who reads the Guitar Player article can see before-and-after waveforms, with and without the transient control circuit, as well as a chart showing the difference in average level that can go into an audio interface. The most dramatic difference was with the bridge pickup, which without the transient control circuit would peak out at 13.4V RMS before clipping the A/D converter. With the transient control circuit, it could peak out at 8.2V RMS. The neck and bridge pickups could deliver about 2 dB higher average level with the transient control circuit. It’s not as much, but still, 2 dB isn’t trivial.

It’s also not just about the A/D conversion. Eliminating that spike makes compressor and limiter gain control circuits soooo much happier. One of the people at Planet Waves who tested the cable said it made some amp sims sound better because they weren’t trying to deal with the spikes – similarly to how tubes “absorb” spikes.

Tom Scholz (the guitar player for Boston) is another red LED fan. We had quite a discussion about their distortion properties, when used instead of conventional silicon or germanium diodes in op amp feedback circuits. That was the secret of my hardware Quadrafuzz circuit (the one both Steinberg and MOTU virtualized).

I know, TMI...sorry. Back to the reviews.
My educational website has launched! Read articles, see videos, read reviews, and more at https://craiganderton.org. Check out my music at YouTube.com/thecraiganderton, and visit my digital storefront at https://craiganderton.com. Thanks!

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Grizzellda
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571 posts since 21 Feb, 2015

Re: The Big Guitar Amp Sim Roundup + Review

Post Tue Oct 15, 2019 3:12 am

I use a PreSonus audio box with an input impedance of 1 MΩ. That is referred to as a Mega Ohm.

It works well... I think that is the basic specification that is required to get a solid guitar signal into a computer. A stompbox compressor might help somewhat too.

And if you have a cool D.I. box, mic inputs can be used. I wanna try this!

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audiojunkie
KVRAF
2917 posts since 19 Apr, 2002 from Utah

Re: The Big Guitar Amp Sim Roundup + Review

Post Tue Oct 15, 2019 7:42 am

Dewdman42 wrote:
Mon Oct 14, 2019 6:05 pm
no a software limiter happens AFTER A/D conversion. So if you digitally clip at the converter its too late.
OK, makes sense. :-) Thank you for helping me understand this! I've misunderstood this for 20+ years! :oops:
Last edited by audiojunkie on Tue Oct 15, 2019 8:12 am, edited 1 time in total.
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audiojunkie
KVRAF
2917 posts since 19 Apr, 2002 from Utah

Re: The Big Guitar Amp Sim Roundup + Review

Post Tue Oct 15, 2019 8:10 am

Anderton wrote:
Mon Oct 14, 2019 11:48 pm
audiojunkie wrote:
Mon Oct 14, 2019 3:27 pm
So, what would be the difference between using a physical/hardware limiter prior to I/O hardware vs putting a software limiter (from within the I/O hardware--like a brickwall limiter vst)? Would it be intent or what one is trying to achieve?
Anything in the software is post-A/D converter, so it doesn't solve the problem of sending spiky transients into the A/D converter....which requires you to turn down the input level, and thus sacrifice input level. But there's much more to the story than that:

* The LED has no overshoot, nobreathing, and nopumping. No active electronic circuit based on gain control can do that.
* The reaction time is instantaneous, so there's no need for look-ahead. The circuit lives in real time.
* The LED has junction capacitance, which increases with voltage. So the more level you put into it, the more capacitance there is (figure about 70 pF max, although that’s not an exact science). This not only shaves off the top, but does soft-, not hard-, clipping above the frequency of the guitar (i.e., where the spikes live).
* You can select an LED with a breakdown voltage to match your pickups. This is why the Gibson circuit worked so well - the pickups levels were a known entity. Luthier Jim DeCola went through a bunch of LEDs to find ones with the ideal breakdown voltage to shave off only the peaks. This is also why you have to use red LEDs. Other colors have too high a breakdown voltage.

Anyone who reads the Guitar Player article can see before-and-after waveforms, with and without the transient control circuit, as well as a chart showing the difference in average level that can go into an audio interface. The most dramatic difference was with the bridge pickup, which without the transient control circuit would peak out at 13.4V RMS before clipping the A/D converter. With the transient control circuit, it could peak out at 8.2V RMS. The neck and bridge pickups could deliver about 2 dB higher average level with the transient control circuit. It’s not as much, but still, 2 dB isn’t trivial.

It’s also not just about the A/D conversion. Eliminating that spike makes compressor and limiter gain control circuits soooo much happier. One of the people at Planet Waves who tested the cable said it made some amp sims sound better because they weren’t trying to deal with the spikes – similarly to how tubes “absorb” spikes.

Tom Scholz (the guitar player for Boston) is another red LED fan. We had quite a discussion about their distortion properties, when used instead of conventional silicon or germanium diodes in op amp feedback circuits. That was the secret of my hardware Quadrafuzz circuit (the one both Steinberg and MOTU virtualized).

I know, TMI...sorry. Back to the reviews.
Fascinating information!! This has been very useful! I've lived under the false impression that a brickwall limiter would work just fine to prevent all clipping. It makes complete sense that clipping at the A/D converter input wouldn't work with a software limiter, but I guess I never even thought about it. I know that a brick wall limiter is great to prevent clipping in-track, but always assumed any clipping took place after the A/D converter. This discussion has corrected a 20+ year false impression! Very useful!!
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Shiek927
KVRian
519 posts since 14 May, 2014

Re: The Big Guitar Amp Sim Roundup + Review

Post Tue Oct 15, 2019 8:19 am

Here's a good question!! S-Gear is my go-to guitar amp sim because it's easy to use and sounds rock solid. What do you guys think are good resources to compliment it, to fill out the areas that it currently doesn't cover? I'm particularly focusing on effects since there's a lack of them in S-Gear, but an actual guitar amp-sim plugin with cabinets and amps would be okay as well if it has offerings that sonically stand up with S-Gear.

Mats Eriksson
KVRist
128 posts since 4 Sep, 2016

Re: The Big Guitar Amp Sim Roundup + Review

Post Tue Oct 15, 2019 8:21 am

Anderton wrote:
Mon Oct 14, 2019 11:07 pm
Then why do you say you need a 128 dB range?
The following image of a plucked guitar string speaks for itself. It is normalized to 0, which shows you just how strong the transient is compared to the average level.
Look, just do the maths or levelling and gain structure with:

1. The pickup choice of yours. Set at a non magnetic string pull level. In height distance from the strings.
2. The string gauge of your choice. Regularly, bread and butter is 010-046. Used by most.
3. Set your levels so the AD/DA doesn't goes into red even at as such as blinking red. With the sample rate and bit rate of your choice. Bread and butter 44.1 Khz 16 bits.
4. Play your "dynamics" with whatever pick of your choice. Ha. Stone pick, plastic thin Sharkfin pick

Now after you did that...and took measurements and gain structured whatever amp sim choice of yours:

1. Raise the pickup level distance to the strings. Or even better, change out to active EMG pickups or some really hot ones. To induce magnetic compression from the get go.
2. Change out string set: to 012-052 or larger. All Stainless Steel perhaps too, with very little nickel into them.
3. DO NOT TOUCH ANY SETTINGS AT YOUR AUDIO INTERFACE AT ALL.
4. Whack the strings with a drumstick. Give it a good whack...

Read the readings of the VU meter or level leds of your interface... :wink: Listen too...to the harsh digital clipping that occurs.

Do the same comparison with any tube amp and keep the settings. Come back here.

You're note even close to maximum dynamics, that am electric guitar can produce. All is dependent on what type of strings (gauge) you use as well as maybe weaker vintage pickups with perceived extra dynamics. I don't want any cable limiting or even hardware or software input limiting. The "natural" compression that virtually every tube amp has inherent, as well as some select magnetic pickups, we should not go into how much EMG active pickups are putting limits to the signal (the 9v battery is the ceiling here), is totally more than enough for me. And if any I/O Audio interface can cope, well then, poor build.

LEHLE Sunday Driver has a 4 mOhm impedance, too, their yellow box. Noisy as hell but upright bass players connects their onboard amplified basses (any pickup) into that one anyway. That's Hi-z.

- - - - - - - - -

I want the audio card to be able to accept all of my instruments without having to make concessions. My vintage weak output Tele with 009 strings, and my EMG equipped bass, with thick gauge strings. Without having to adjust for bit depth and sample rates. Your Mileage May Vary as always. Alas as I asked a FAQ on IK mulitmedia on their new Axe I/O unit I can't connect at the same time a passive guitar into input one, and another cable with my EMG bass into input 2 at the same time. Pity. I can...but... it doesn't work out.

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Anderton
KVR Expert
140 posts since 4 Mar, 2004
KVR Expert

Re: The Big Guitar Amp Sim Roundup + Review

Post Tue Oct 15, 2019 8:59 am

Mats Eriksson wrote:
Tue Oct 15, 2019 8:21 am
Do the same comparison with any tube amp and keep the settings. Come back here.

You're note even close to maximum dynamics, that am electric guitar can produce. All is dependent on what type of strings (gauge) you use as well as maybe weaker vintage pickups with perceived extra dynamics.
I think you're missing my point about dynamic range. Of course, if you put more signal into something you get more signal out. My point is dynamic range represents the difference between the loudest and softest levels. The transient of a guitar, the initial peak, is huge compared to the average level that it settles into shortly after the peak.

Of course, if you put more signal strength into the pickup, you'll get more output. That's not relevant to my point about peak transients, and why absorbing them provides more consistent performance with digital gear.
My educational website has launched! Read articles, see videos, read reviews, and more at https://craiganderton.org. Check out my music at YouTube.com/thecraiganderton, and visit my digital storefront at https://craiganderton.com. Thanks!

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