Axe FX II with real cabs - cab sim off -> gain structure is completely different

[sprint]

I know this thread is stupidly old, but I always had this problem with my axe fx standard and just bought an axe fx iii. I figured out the issue finally.

I'm using a Mesa 2x12 with V30s in it, and i couldn't figure out why bypassing the cab sim sounded like a chainsaw (as you described). However, turning cab sim on made it sound a little too dark through my cab. The issue is that V30 speakers have a frequency response range of 70-5000hz (according to celestion's website). The axe fx was sending the full frequency range to the cab, and the speakers were trying to put out stuff in the 10000hz+ range. All I did to fix this was add a filter to roll the highs off starting at 5000hz. It sounds exactly like my real triple rectifier head now. I'm not sure if there's a better way to do this. Maybe Cliff can chime in. Basically just figure out what the upper range of your particular speaker's response is, and filter out anything above that.

Now my patch sounds pretty consistent. I have the chain split before the filter. Part 1 goes to that filter and then into output 1 going to my real cab (no cab sim) and i have part 2 going cab sim and then into output 2 (into my audio interface). I'm using the legacy 4x12 Metal cab sim that i used to use on the axe fx standard so the cab characteristics are slightly different, but it sounds very consistent now. The reason I wanted to do this is that I like to jam out through my real cab while i'm recording. My studio monitors have a subwoofer, so monitoring through my monitors without my post-EQ sounds very woofy and not fun. This is also probably a good method for people who record and also gig. You can have one patch that is consistent for both applications. The only thing you should do differently than me for the sake of consistency is use a cab sim that is similar (if not identical) to your real cab.

I do the same on my real cabs but I'm not sure I quite understand logically why it is necessary as I would expect the Axefx amp model (pre cab) to be sending out a frequency range similar to what would come out of a real equivilent amp head. My best guess is that a cab IR may roll off more high end than a real cab because the IR represents a mic'd cab including mic and mic pre coloring where as the real cab does not include any mic / mic pre coloring - so, if I'm used to hearing the IR alternative, and comparing both, the real cab will always sound much more "raw". WRT cab sim on into a real cab, I never understand how this can sound good (sending a mic'd real cab sound into a real cab - too dark would be expected).

 

[M3T1]

I do the same on my real cabs but I'm not sure I quite understand logically why it is necessary as I would expect the Axefx amp model (pre cab) to be sending out a frequency range similar to what would come out of a real equivilent amp head. My best guess is that a cab IR may roll off more high end than a real cab because the IR represents a mic'd cab including mic and mic pre coloring where as the real cab does not include any mic / mic pre coloring - so, if I'm used to hearing the IR alternative, and comparing both, the real cab will always sound much more "raw". WRT cab sim on into a real cab, I never understand how this can sound good (sending a mic'd real cab sound into a real cab - too dark would be expected).

I figured the axe fx model would be similar to my real Mesa and roll the highs off better but i guess it doesn't. I tried so much other stuff and then went back into producer mode and was like 'let me see if i can EQ this'. And sure enough, 2 minutes later everything sounded perfect just using a lowpass filter -_-

IR through real cab sounds okay. I played that way for years with my old axe fx. It's just darker sounding (way less highs). I used to use a Rocktron Velocity 300 and the definition knob helped compensate for that (basically just adds highs back in). Not ideal, but it worked for my purposes for the last 5-6 years. I just was determined with the new axe fx to figure it out. I now use a Matrix amp, so I have no more coloring features on the poweramp. Glad i figured it out. It sounds awesome now.

 

[joegold]

Sounds more like you're using a tube power amp designed for guitar rigs.
If you can actually find a truly FRFR tube power amp with enough juice for your needs, that would probably be fine.
But you'll only find them in audiophile shops.
Tube power amps designed for guitar players will drastically colour the sound and will usually distort at louder volume level too.
If your Preset has some simulated pwr amp distortion in it too, then you'll be adding distortion on top of that.

A neutral, highly accurate FRFR solid state power amp, like a Matrix GT1000x is what you need for that application.
Each amp sim you use this way (sans Cab Block) will sound very similar to what that real amp would sound like through that cabinet of yours.

If you are already using a neutral ss power amp, then something else is misconfigured somewhere in your Presets.

 

[joegold]

A V30 can not reproduce much of anything that's audible above 5k.
Sending a signal with info above 5k just does not get reproduced.

 

[M3T1]

Sounds more like you're using a tube power amp designed for guitar rigs.
If you can actually find a truly FRFR tube power amp with enough juice for your needs, that would probably be fine.
But you'll only find them in audiophile shops.
Tube power amps designed for guitar players will drastically colour the sound and will usually distort at louder volume level too.
If your Preset has some simulated pwr amp distortion in it too, then you'll be adding distortion on top of that.

A neutral, highly accurate FRFR solid state power amp, like a Matrix GT1000x is what you need for that application.
Each amp sim you use this way (sans Cab Block) will sound very similar to what that real amp would sound like through that cabinet of yours.

If you are already using a neutral ss power amp, then something else is misconfigured somewhere in your Presets.

I'm using a Matrix GT800FX power amp.

Also, that is not true about the V30. The frequency response range is 70-5000hz according to their website, but if you look at their 8 ohm frequency response line graph, you'll see that it responds to frequencies in the 10k-20k range about as well as it responds to sub bass (under 60hz). I'm not sure why these frequencies are so prominent coming out of the axe fx with no cab model, but nonetheless, it was an issue. The best analogy I can give is if you sent a preamp to your DAW and forgot to load an IR. It sounded like a high pitch chainsaw. Absolutely ear piercing. Once I added that filter, it sounded amazing.

This forum won't let me link to celestion's site, but if you just go to the V30 product page on their site, you can see the 8 ohm graph I'm talking about.

 

[joegold]

I'm a bit surprised to find out that you're already using a GT800.
FWIW I owned one for a short bit but it sounded quite unmusical to me compared to the GT1000 I already owned.
Basically, I found the top end really brittle compared to the 1000.
I bought the 800 just to compare.
But most GT800 owners don't feel that way.
It may have been that I had a faulty unit.
But when I returned it to Matrix, nobody checked it out as far as I know, so I guess I'll never know.

But speaking of other people's experiences being different....
Your experience with your rig is the outlier here.
Virtually nobody else who runs their Fractal amp models into a ss pwr amp and guitar cabinets is experiencing what you're experiencing.
Most folks who do that are chasing the 'amp/cab in the room' feeling and with amp modelling and this is the only way to do that.

So I go back to my comment above that you must have something else misconfigured somewhere in your Presets.
Have you tried dialing in the tones with the GT800/V30s first and then trying to find an IR that reproduces that tone inside your FRFR system?
It sounds like you may have been dialing in your tones using the Cab Block with IRs actives, either on studio monitors or FRFR monitors, and then being surprised that your real speakers don't sound similar to that IR.
In both these scenarios, it may be the IR you're using that's skewing your perceptions of the non-IR tone.
If you can't dial in a great tone using the GT and the V30s, something is wrong.
It should be easier to do that than to dial in a decent FRFR tone using the Cab Block and IRs.

And anything below 100hz that you send into a V30 will be attenuated compared to frequencies above that.
E.g. If you play a bass guitar through those speakers you should notice that the lowest notes are quieter than the notes above 100hz.
Likewise, on the top end, the speaker will reproduce stuff up to about 8k but it will be much quieter than frequencies below 5k.
These attenuated frequencies will not be distorted any more than the frequencies that lie within the practical range of the speaker.
They'll just be quieter.

 

[joegold]

PS
A good experiment for you might be to buy the V30 IRs from Celestion's web site, dial in some tones on FRFR monitors, and them compare them to the GT/V30/sans Cab Block signal path too.

 

[M3T1]

I'm a bit surprised to find out that you're already using a GT800.
FWIW I owned one for a short bit but it sounded quite unmusical to me compared to the GT1000 I already owned.
Basically, I found the top end really brittle compared to the 1000.
I bought the 800 just to compare.
But most GT800 owners don't feel that way.
It may have been that I had a faulty unit.
But when I returned it to Matrix, nobody checked it out as far as I know, so I guess I'll never know.

But speaking of other people's experiences being different....
Your experience with your rig is the outlier here.
Virtually nobody else who runs their Fractal amp models into a ss pwr amp and guitar cabinets is experiencing what you're experiencing.
Most folks who do that are chasing the 'amp/cab in the room' feeling and with amp modelling and this is the only way to do that.

So I go back to my comment above that you must have something else misconfigured somewhere in your Presets.
Have you tried dialing in the tones with the GT800/V30s first and then trying to find an IR that reproduces that tone inside your FRFR system?
It sounds like you may have been dialing in your tones using the Cab Block with IRs actives, either on studio monitors or FRFR monitors, and then being surprised that your real speakers don't sound similar to that IR.
In both these scenarios, it may be the IR you're using that's skewing your perceptions of the non-IR tone.
If you can't dial in a great tone using the GT and the V30s, something is wrong.
It should be easier to do that than to dial in a decent FRFR tone using the Cab Block and IRs.

And anything below 100hz that you send into a V30 will be attenuated compared to frequencies above that.
E.g. If you play a bass guitar through those speakers you should notice that the lowest notes are quieter than the notes above 100hz.
Likewise, on the top end, the speaker will reproduce stuff up to about 8k but it will be much quieter than frequencies below 5k.
These attenuated frequencies will not be distorted any more than the frequencies that lie within the practical range of the speaker.
They'll just be quieter.

Originally I was dialing in tones DI using a cab block, but when I figured out this filter method, I was starting from scratch. No cab block. Just dialing it in using my 2x12. I had the same problem with my axe fx standard and i have tried with 2 different power amps (Rocktron Velocity 300 and the Matrix GT800FX). Maybe I'm just sensitive to really high frequencies or something.

One thing i discovered today is that the default negative feedback setting on the dual rectifier amp model is incredibly low. It was set to 1.0. Bumping this up to simulate the color a tube power amp would give you really rounded off the top end. I think i have it somewhere around 5.5 now, and it sounds really good. I took the filter off and it sounded better. Still not to my liking, but better for sure. There just seems to be some hissing above 10k that is really bothering me. Maybe I'm just sensitive to it idk...

 

[M3T1]

Alright I made a lot of progress. I needed to mess with the sag setting and the negative feedback setting in the poweramp section. I also realized that my output signal was really weak. I went into the monitors view and upped my output on the channel going to the poweramp until it was near 0db. Before I did that, it was really really low (-12db or so). I think that contributed to it a lot. Driving it harder without clipping the output really filled the tone out a lot.

I also A/B'ed it with my original axe fx, and the original axe sounds fine through the matrix with the cab model bypassed. The axe fx III has more of that high end hiss tho. It doesn't matter which amp model I use either. It's there no matter what. Just sounds a little bit thinner than the old one. I have to be doing something wrong. I just can't figure out what lol.

 

[Shask]

I know this thread is stupidly old, but I always had this problem with my axe fx standard and just bought an axe fx iii. I figured out the issue finally.

I'm using a Mesa 2x12 with V30s in it, and i couldn't figure out why bypassing the cab sim sounded like a chainsaw (as you described). However, turning cab sim on made it sound a little too dark through my cab. The issue is that V30 speakers have a frequency response range of 70-5000hz (according to celestion's website). The axe fx was sending the full frequency range to the cab, and the speakers were trying to put out stuff in the 10000hz+ range. All I did to fix this was add a filter to roll the highs off starting at 5000hz. It sounds exactly like my real triple rectifier head now. I'm not sure if there's a better way to do this. Maybe Cliff can chime in. Basically just figure out what the upper range of your particular speaker's response is, and filter out anything above that.

Now my patch sounds pretty consistent. I have the chain split before the filter. Part 1 goes to that filter and then into output 1 going to my real cab (no cab sim) and i have part 2 going cab sim and then into output 2 (into my audio interface). I'm using the legacy 4x12 Metal cab sim that i used to use on the axe fx standard so the cab characteristics are slightly different, but it sounds very consistent now. The reason I wanted to do this is that I like to jam out through my real cab while i'm recording. My studio monitors have a subwoofer, so monitoring through my monitors without my post-EQ sounds very woofy and not fun. This is also probably a good method for people who record and also gig. You can have one patch that is consistent for both applications. The only thing you should do differently than me for the sake of consistency is use a cab sim that is similar (if not identical) to your real cab.

I have done this in the past, and it can work well. Just put a filter after the amp and cut below 60hz and above about 6k. I know this is common in the cab block, but it can help into a SS amp and guitar cabs also.

However, I found the high cut control in the amp block advanced controls (I want to say Preamp page in Axe-Edit) works pretty well also while sounding a bit more natural. It can take off a bit of edge. I will set it between 7k and 10k, spending on the sound.

 

[M3T1]

I have done this in the past, and it can work well. Just put a filter after the amp and cut below 60hz and above about 6k. I know this is common in the cab block, but it can help into a SS amp and guitar cabs also.

However, I found the high cut control in the amp block advanced controls (I want to say Preamp page in Axe-Edit) works pretty well also while sounding a bit more natural. It can take off a bit of edge. I will set it between 7k and 10k, spending on the sound.

Yeah I've been using the high cut in the amp block. Super useful for sure.

 

[M3T1]

There is another difference i discovered with several amp models (Diezel and 5150) that I like to use. The new axe fx actually has the gain knob respond the way those amps do in real life, which is to say that 0 is neutral. The confusing thing here is a rectifier is not like this. 12 o'clock is neutral on a mesa and then you can reduce or add gain accordingly. I knew this difference about these amps in real life, but I didn't realize the axe changed to reflect it. My gain was WAY too high using those models which attributed to the high-end fuzz problem.

I mention this because my axe fx standard does not appear to be this way. In order to get a comparable tone to my old lead tone, I have to have gain at around 3 (9 o'clock ish) on the axe fx iii, whereas on the axe fx standard, i'd have it at 6.5 (2 o'clock). Almost identical tone now between the two. I feel so dumb...

 

[Billbill]

I think using the stock IRs in about 90% of my presets through two “real” cabs sounds and feels better to me and this is both in my large jam space or playing out with the fellas. Not sure why but I like it lol. Just do whatever makes you feel it! \m/