Axe III via Studio Monitor v.s. Tube Combo at the Same Volume

guys unsatisfied with class D or even the Matrix stuff might want to try the old-school lead sled PA amps. Crown 2402, Crest CA9, QSC RMX 2450, etc.

These amps are very heavy, so they won't save weight versus a tube amp, but they have gobs of power on reserve. A lot of bass players still work with these in their rigs because they just have a certain slam that some of the new, lighter stuff doesn't.

I have a CA9, and vastly preferred it to a Mesa M180 (180-watt mono block) and Fryette 2:90:2.
 
FractalAudio said:
Turn the Power Tube Bias down. That controls the shape of the response. Fenders are notoriously biased cold whereas the models are biased warm). Then read my thread on Why Your Amp Doesn't Sound Like Our Amp.

You'll never get the same experience using FRFR compared to AITR. It's physics. It's not a bunch of internet myth and pseudo-science about "mojo" and "tube magic".

I routinely A/B my tube amps against an Axe-Fx into a SS power amp into a standard guitar cab and I can ALWAYS make the Axe-Fx sound as good or better. This isn't subjective. It's objective because the Axe-Fx doesn't hum and crackle and do all the other annoying things the tube amps do.
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Thanks Cliff.

Lower bias certainly increase the dynamics a little bit (I learned about this trick since olds days with Helix, which is more limited), and another thing that change the dynamic response much more powerfully is the "Input Dynamic", a nudge of it would sort of push the response a little bit more like the feel of the tube amp, but too much will quickly make it fake...

Lastly, using "SS Pwr Amp + Cab" instead of "FRFR" in Speaker Drive setting also improves the dynamic for me in firmware 15 and earlier, this setting somehow has much less effects after Cygnus... @FractalAudio , not sure why?

Input dynamic is not a real control in real tube amp, however, this is the kind of things that could become the real magic in the modeling world, e.g.

1. If we are able to figure out, quantify and refine what makes tube amp response attractive, we can provide that without the physical constraint of real tube amp in the modeling world, and potentially help modeling not just imitate but surpass the response experience from old tube amps!

2. Modeling could/should be thinking out of the box/constrains of real tube amps, perhaps. Nothing wrong with advance/imaginary controls like Input Dynamic, we might want more of them!

3. It's like a combination of "functional vs imperative" approaches/methodologies, provides controls to directly achieve certain end results, not confined by and on top of component level modelings.

Not sure if that makes sense...

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The reason open-back combos feel more "dynamic" is because you get the reflection from the back hit you shortly after you pluck the note. You get the direct sound from the front and the sound from the back goes out, hits a wall and comes back 10-20 ms later giving the illusion of more "dynamics". There's no radiation from the back with monitors (unless they're dipoles). Like I said, it's physics. Increasing Input Dynamics will give a similar response since it's essentially an expander with a slight lag due to the detector latency.

If you want that same experience you need to use an open-back cab or dipole monitor.

The only TRUE way to compare an amp with the model is to use a load box or put the amp in an isolation room. Any other technique is apples-to-oranges.
 
This is kind of a fascinating topic for me. Does anybody have a resource for "best practices" when adding a "rear" mic to your cab block? I've always just mixed them low, but if there's something else to do to account for the delay Cliff is talking about, I'd love to hear about it.
 
You'll have to just experiment and use what sounds best to you. The actual delay from the back of the cab will depend on how far it is from any reflective surfaces. If the cab is back up against a wall the reflection will reach you sooner than if it's in the middle of an open room. Speed of sound is roughly 1 foot per millisecond, so for example if the back of the cab is 5 feet from a wall, the wave from the back of the speaker will hit you roughly 10 ms later (5 feet there + 5 feet back) than the wave from the front of the speaker, assuming you're standing in front of the cab.

A wider range of delay times in the cab block's align section would make this kind of thing a lot easier to do. Right now it's limited to around 1 ms, but a range of up to around 20 ms per cab would be very cool to simulate things like cab back reflections and distant mics.
 
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cardinal said:
guys unsatisfied with class D or even the Matrix stuff might want to try the old-school lead sled PA amps. Crown 2402, Crest CA9, QSC RMX 2450, etc.

These amps are very heavy, so they won't save weight versus a tube amp, but they have gobs of power on reserve. A lot of bass players still work with these in their rigs because they just have a certain slam that some of the new, lighter stuff doesn't.

I have a CA9, and vastly preferred it to a Mesa M180 (180-watt mono block) and Fryette 2:90:2.
Click to expand...

I know the Crest CA9 uses a toroidal transformer, which I remember somewhere around 2008/2009ish Cliff and even Jay Mitchell, saying to stay away from for audio quality. This came up in a discussion about the then hugely popular choice, ART SLA-2, since it uses one.

I remember both them saying to choose an EI-frame power amp with eight times the power of what ever cab you were going to be driving to account for the way a tube based power amp releases power and "punch."

I can't find the discussion to link anymore because it was on the old BB Based forum, which no longer exists.

Article about EI-FRAME vs TOROIDAL

Would love some recommendations for EI-Frame power amps though.
 
biggness said:
I know the Crest CA9 uses a toroidal transformer, which I remember somewhere around 2008/2009ish Cliff and even Jay Mitchell, saying to stay away from for audio quality. This came up in a discussion about the then hugely popular choice, ART SLA-2, since it uses one.

I remember both them saying to choose an EI-frame power amp with eight times the power of what ever cab you were going to be driving to account for the way a tube based power amp releases power and "punch."

I can't find the discussion to link anymore because it was on the old BB Based forum, which no longer exists.

Article about EI-FRAME vs TOROIDAL

Would love some recommendations for EI-Frame power amps though.
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Fryette and Aguilar make some extremely well regarded power amps with toroidal transformers, so I'm skeptical of claims they are inferior, though there have been rumblings of such things.

I'm going to guess there are difference far beyond a toroidal transformer between something like the CA9 and the SLA2.

The Crown 2402 uses the iron core/laminated transformers, I believe.
 
cardinal said:
Fryette and Aguilar make some extremely well regarded power amps with toroidal transformers, so I'm skeptical of claims they are inferior, though there have been rumblings of such things.

I'm going to guess there are difference far beyond a toroidal transformer between something like the CA9 and the SLA2.

The Crown 2402 uses the iron core/laminated transformers, I believe.
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I really don't know anything about it other than what Cliff and Jay said.

But here are some audiophile/tonesnobs talking about it lol
 
Way back in the early 80s I ran Hafler (Robert) mosfet amps into monster EV1 Eliminators P.A.

I miss those amps; speakers - not at all!
 
cardinal said:
Sounds like a good transformer in a good amp is good, and a poor transformer in a poor amp is less good.
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I took it as a better transformer in an equal design is better. The highly acclaimed Otsuka amp that everyone would kill their mothers to have uses EI-Frame.

Could be the missing link that some feel isn't present.
 
Did another session of comparison today, here is another way/analogy to describe the different dynamic responses from Tube amp and SS:

1. Tube amps feels like the tone is squeezing through an elastic tube, depending on how hard my pick attacks the string, the signal expand the elastic circumference, and the notes feels/blooms more naturally and immediately, spongy and elastic. Hence one feels the tone fights back a bit. With volume high, it remains easy to play quiet with gentle pick attacks.

2. SS amps respond like the tone going through a tube that is NOT quite elastic, the canal feels blocked at the very beginning and then suddenly wide open with the tone/dynamic rushing through. One doesn't feel the tone fight back, and with higher volume it's harder to pick quiet.

Every time, I fire up one of my nice tube combos, it always reminds me how inspiring an experience it is to play through the real thing.
 
FractalAudio said:
Turn the Power Tube Bias down. That controls the shape of the response. Fenders are notoriously biased cold whereas the models are biased warm). Then read my thread on Why Your Amp Doesn't Sound Like Our Amp.

You'll never get the same experience using FRFR compared to AITR. It's physics. It's not a bunch of internet myth and pseudo-science about "mojo" and "tube magic".

I routinely A/B my tube amps against an Axe-Fx into a SS power amp into a standard guitar cab and I can ALWAYS make the Axe-Fx sound as good or better. This isn't subjective. It's objective because the Axe-Fx doesn't hum and crackle and do all the other annoying things the tube amps do.
Click to expand...
This SSamp + guitarcab combination is something I might ultimately try for kicks at home. If not I never ever had the feeling soundwise speaking there was a difference when playing with a band in rehearsal or on stage; except that with the Axefx I can bring in all I need in one walk from the car to the bar.

Edit : don't forget too that the playing volume level and room volumetry does alter the sound as the interaction of guitar and the room is an important part of the feel you may have. Most people playing tube amps at home play at less than one meter from the amp; which already is not feeling the same as when you are at 5 meters for example
 
Mark Al said:
Thanks Cliff.

Lower bias certainly increase the dynamics a little bit (I learned about this trick since olds days with Helix, which is more limited), and another thing that change the dynamic response much more powerfully is the "Input Dynamic", a nudge of it would sort of push the response a little bit more like the feel of the tube amp, but too much will quickly make it fake...

Lastly, using "SS Pwr Amp + Cab" instead of "FRFR" in Speaker Drive setting also improves the dynamic for me in firmware 15 and earlier, this setting somehow has much less effects after Cygnus... @FractalAudio , not sure why?

Input dynamic is not a real control in real tube amp, however, this is the kind of things that could become the real magic in the modeling world, e.g.

1. If we are able to figure out, quantify and refine what makes tube amp response attractive, we can provide that without the physical constraint of real tube amp in the modeling world, and potentially help modeling not just imitate but surpass the response experience from old tube amps!

2. Modeling could/should be thinking out of the box/constrains of real tube amps, perhaps. Nothing wrong with advance/imaginary controls like Input Dynamic, we might want more of them!

3. It's like a combination of "functional vs imperative" approaches/methodologies, provides controls to directly achieve certain end results, not confined by and on top of component level modelings.

Not sure if that makes sense...

View attachment 83615
Click to expand...
Just for my perusal, on a D30 amp for FM3 how do I turn the power tube bias down ? Raise cathode resistance ?
Guess the input dynamics is not available on fm3 as I don't find that control in fm3 edit, or am I looking at the wrong place ?
 
crdark said:
Does anyone know a better alternative to the SD Power Stage thats avaiable in europe?
Click to expand...
Maybe the Orange Pedal Baby, which is a 100W class A/B power amp, there are a few comparisons on YouTube with the Orange fairing quite favourably.
 
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