Strange sounds when Cab block bypassed

L

LiamH

Inspired
Hi All,

Slightly new to this (first post). Axe-FX II XL with Quantum 2.0 - have been using for a couple of months with headphones while I try to make it into a replacement for an out of control tube amp collection habit.

Have been working on a model to emulate a Marshall JMP 2203 (basically Brit 800) and my effects pedal board, and over headphones all sounding much like the physical amp itself. I did notice that with cab block bypassed it sounded thin, brittle, and that the power amp distortion sounded rather strange.

Just got a Matrix GT1000FX, and while I am waiting for my FRFR cab to be built, thought I'd try it through one of my 4x12 cabs. With the cab block bypassed it sounds very much like it does through headphones with cab block bypassed. Turning the cab block back on improves matters dramatically. Am I missing something obvious? I may or may not ever gig with the Axe-FX, Matrix and 4x12, but I'd love to have the option. It's pretty usable with the cab block switched on, but it doesn't seem right that I have to.

Any help would be very much appreciated - aside from this quirk everything about the Axe-FX has been remarkably good (even reminding me why I ended up selling so many amps in the past - sounds just like them!)

Liam
 
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With headphones or a FRFR speaker, the Cab block is of course not meant to be bypassed.

I don't have much experience using the Axe with real amps and cabs, but I do know that you need some volume with them, more than FRFR or headphones. Especially with a high powered amp. Many real amps don't sound good at very low volumes either. Real cabs need some air being moved to sound right. Not sure if this is what's happening for you, but thought I'd mention it.
 
Not sure what's going on. I run a Matrix GT1000 through a pair of 2x12 (real/Friedman w/V30s) stereo cabs and it sounds phenomenal. You must turn it up and move air as Chris says above. Fletcher-Munson, Cabs, resonance, etc.

Is there a fuzz/drive or EQ in the patch that's on/effecting tone? Try resetting the amp? Wah?

Is it only that patch? Have you tried others?
 
LiamH said:
Just got a Matrix GT1000FX, and while I am waiting for my FRFR cab to be built, thought I'd try it through one of my 4x12 cabs. With the cab block bypassed it sounds very much like it does through headphones with cab block bypassed.
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Welcome to the community!

What speakers are mounted on your 4x12 cab? Because that makes a huge difference. What "real amp" did you play through your 4x12 cab before becoming (I assume: a proud) Axe-Fx II-owner?
 
Chris@AxeFxTutorials said:
With headphones or a FRFR speaker, the Cab block is of course not meant to be bypassed.

I don't have much experience using the Axe with real amps and cabs, but I do know that you need some volume with them, more than FRFR or headphones. Especially with a high powered amp. Many real amps don't sound good at very low volumes either. Real cabs need some air being moved to sound right. Not sure if this is what's happening for you, but thought I'd mention it.
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Good thought, but I was already aware of the physical aspects. I think the latest firmware unwittingly sorted my problem out, and at the same time made me realise I actually wanted a Friedman BE100 for the last 20 years.

I think the issue is that the Marshall 2203 has some "unusual" design aspects that are probably difficult to model, and some fairly strange behaviour in terms of the way the signal is processed in the preamp stages. Mine has been much modified over the years, and I think some of the stranger sounds coming out of the cab were things I couldn't dial out in the model, but I have at some point dialed out of my own amp with cap and resistor changes on the first 2 preamp tubes amongst other tweaks. The Brit 800 Mod model irons out a few of the details, but is much darker than my one, and has a lot more gain.

I upgraded to Quantum 2.04 this afternoon, and was checking out the new Friedman BE V2 version. It sounds a lot like my 2203, in fact in many ways probably better. I'll have a play this week - I think it might be just what I always wanted. Other bizarre thing, the cab in the BE preset matches the 4 x 12 I am using incredibly well. I can set up in headphones with cab modeling active, flick on the power amp and take cab modeling out, and while they aren't indistinguishable, they are really close.

Happy camper now, I can make this work for me. I think I just chose a particularly tricky model for my first attempt. Very impressive piece of kit this Axe-FX!

Liam
 
Stillbruch said:
Welcome to the community!

What speakers are mounted on your 4x12 cab? Because that makes a huge difference. What "real amp" did you play through your 4x12 cab before becoming (I assume: a proud) Axe-Fx II-owner?
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I have a couple of 4 x 12s, and I'm playing through Celestion Hot 100s in this one. Real amps re a modified Marshall 2203, a stock Marshall 2203, an Orange Rockerverb 50 MkIII until a few weeks ago, a 100 watt Matamp, a 65 Amps Whiskey, and a Marshall 1986 converted to 1987 specs. I also have a load of combos, so if I can get this work for me it's going to give me back a lot of space in the music room.

Have just done a bit more playing around, and it does seem that the cab IRs were just masking some quirks of the Brit 800 amp model. I don't doubt that the same quirks are present in the signal chain of the real amp, but maybe less audibly so.

Liam
 
Pay attentiom to the speaker page in the amp block. Axe fx has no idea what cab is connected, so you have to dial in these parameters manually, unlike real amps where these parametera are automatic/natural.
 
Hadn't thought about that one at all, thanks for bringing it up. I'll have a read through the manual about this, as I'm not entirely sure exactly how the Fractal simulations use the parameters - I am guessing I'll need to approximate the way in which the physical speakers would load the power tubes if the could "see" them through the output transformer.
 
LiamH said:
Hadn't thought about that one at all, thanks for bringing it up. I'll have a read through the manual about this, as I'm not entirely sure exactly how the Fractal simulations use the parameters - I am guessing I'll need to approximate the way in which the physical speakers would load the power tubes if the could "see" them through the output transformer.
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There are some interesting posts about that topic (amongst others) in the "Tech Notes" subsection: http://forum.fractalaudio.com/forums/tech-notes.77/. Most notably: http://forum.fractalaudio.com/threads/about-speaker-lf-resonance.78003/; http://forum.fractalaudio.com/threads/about-matching-your-cabinets-resonant-frequency.79816/.
 
LiamH said:
I think the latest firmware unwittingly sorted my problem out, and at the same time made me realise I actually wanted a Friedman BE100 for the last 20 years.
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:D Try the Dirty Shirley too while you're at it! I had the same lightbulb moment with the BE100 model, the smallbox, AND the Dirty Shirley.

FreeMind said:
Pay attentiom to the speaker page in the amp block.
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This is what I came here to say. Usually just sweeping the low and high frequencies gets me 90% of the way there, and occasionally bumping the resonance up or down a tad solves all my issues when running to cabs. You really want to do this at gig volume with your other instruments in the mix too tho, because this is pretty much how you decide where the guitar will sit.
 
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