Different sound radiations with a real cab compared to a tube amp

MrPond

MrPond

Experienced
Hey folks!

I couldn't find anything about my topic and maybe someone has an idea? ...

So! My main point is, that my FM3/PowerStage 170 combination does have a different sound radiation compared to my real amp's (hooked up to the same cab of course)
I mean: The FM3 sound is more like a concentraded "beam" and my real amp tones are more "wide open". Hard to describe ...
Like, you have to stand more in the cab's sound beam to get the same compared to my real amp's.
To compensate this, i have to crank my FM3 more than my real amps and the "amp in the room" feeling is somehow diminished.
The question is - why? Is this a "problem" of my SD PS170 power amp? ...

So long,
Niklas
 
MrPond said:
Hey folks!

I couldn't find anything about my topic and maybe someone has an idea? ...

So! My main point is, that my FM3/PowerStage 170 combination does have a different sound radiation compared to my real amp's (hooked up to the same cab of course)
I mean: The FM3 sound is more like a concentraded "beam" and my real amp tones are more "wide open". Hard to describe ...
Like, you have to stand more in the cab's sound beam to get the same compared to my real amp's.
To compensate this, i have to crank my FM3 more than my real amps and the "amp in the room" feeling is somehow diminished.
The question is - why? Is this a "problem" of my SD PS170 power amp? ...

So long,
Niklas
Click to expand...
What you’re describing seems... unlikely. The physical pattern of sound dispersion in space is determined by the cab, not by the power amp. I think you’re hearing something else.
 
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I'd go a step further and say that it's not just unlikely, but physically impossible (for the same reason Rex is saying).

I do believe they sound different, but it just can't be a different 'sound radiation'
 
I can dial in similar tones and match the amp level (by meter) and i get "more" from my tube amps.
I trust you guys, so it's not the power amp or the cab - which means, there are maybe some frequencies missing in my FM3 sounds?
I guess i have to dig deeper (after Cygnus) and compare the signals in a better way ... any suggestions to do that? Mic my cab, record those two and compare the frequencies?
 
Check and make sure your output is set to mono, and that you don't have any room ambience running on your cab block. Those two things can really mess with the sound of going into a real cab.
 
joshriggsFM3 said:
Check and make sure your output is set to mono, and that you don't have any room ambience running on your cab block. Those two things can really mess with the sound of going into a real cab.
Click to expand...

  • out 2 output mode is set to mono (sum L+R)
  • cab block is not in use in this scenario, because i'm talking about a real cab :)
 
MrPond said:
  • out 2 output mode is set to mono (sum L+R)
  • cab block is not in use in this scenario, because i'm talking about a real cab :)
Click to expand...
Haha, derp. I'm still having coffee and waking up this morning.

Also check the speaker tab on your amp block. There's a toggle somewhere in there that you set for FRFR or S.S. Power Amp + Cab. It defaults to FRFR.
 
MrPond said:
I couldn't find anything about my topic and maybe someone has an idea? ...

So! My main point is, that my FM3/PowerStage 170 combination does have a different sound radiation compared to my real amp's (hooked up to the same cab of course)
I mean: The FM3 sound is more like a concentraded "beam" and my real amp tones are more "wide open". Hard to describe ...
Like, you have to stand more in the cab's sound beam to get the same compared to my real amp's.
To compensate this, i have to crank my FM3 more than my real amps and the "amp in the room" feeling is somehow diminished.
The question is - why? Is this a "problem" of my SD PS170 power amp? ...
Click to expand...
Your question makes no sense. The cabinet and speaker is always responsible for sound radiation/dispersion and the FM3/real amp/power amplifier will make absolutely no difference in how the sound is dispersed.

The signal enters the cabinet, the speaker moves, sound emanates from the cone and the cabinet resonates. It’s always the same because it’s physics.

You didn’t tell us enough about your “real amp” and how you have the FM3 connected for us to do anything else but guess so explain your systems. The manuals cover FM3+power amp+cabinet connections and have advice.

https://wiki.fractalaudio.com/wiki/index.php?title=Mono_and_stereo
https://wiki.fractalaudio.com/wiki/index.php?title=Amp_and_Cab_modeling_for_beginners
https://wiki.fractalaudio.com/wiki/index.php?title=Connections_and_levels
https://wiki.fractalaudio.com/wiki/index.php?title=Describing_sound
 
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joshriggsFM3 said:
Haha, derp. I'm still having coffee and waking up this morning.

Also check the speaker tab on your amp block. There's a toggle somewhere in there that you set for FRFR or S.S. Power Amp + Cab. It defaults to FRFR.
Click to expand...

Haha no problem :) Yeah, everything is set to SS Poweramp + Cab.

Sixstring said:
Most of the time it is EQ and/or volume!
Click to expand...

Maybe ... i think so, too.

Greg Ferguson said:
Your question makes no sense. The cabinet and speaker is always responsible for sound radiation/dispersion and the FM3/real amp/power amplifier will make absolutely no difference in how the sound is dispersed.
Click to expand...

I think my question makes sense, because it's what i hear (and my band buddy, as well)
The sound of the FM3 is more in a beam compared to my tube amp. Almost the same sound, equally leveled.
It it what it is - because the cab is the same constant in this setup, the "issue" has to be the FM3 or the power amp.
My question was what the issue can be - so, i have to disagree - i think (almost) every question is a valid question if something is unclear ;)
I'm not a physicist, only a musician ..

Another example: If i stand behind my cab, my tube amp sounds "thicker" (not bassy, like ... more "beef").
Again - hard to describe! But it's what i can reproduce on different cabs in different environments.
 
Get a decibel meter or phone app and actually make sure you are getting equal output volume from the FM3 + PS. Also see if pushing more level to the Powerstage with its volume control lower works better than lower FM3 level but higher PS volume.
 
MrPond said:
Hey folks!

I couldn't find anything about my topic and maybe someone has an idea? ...

So! My main point is, that my FM3/PowerStage 170 combination does have a different sound radiation compared to my real amp's (hooked up to the same cab of course)
I mean: The FM3 sound is more like a concentraded "beam" and my real amp tones are more "wide open". Hard to describe ...
Like, you have to stand more in the cab's sound beam to get the same compared to my real amp's.
To compensate this, i have to crank my FM3 more than my real amps and the "amp in the room" feeling is somehow diminished.
The question is - why? Is this a "problem" of my SD PS170 power amp? ...

So long,
Niklas
Click to expand...
If I was you I wouldn't lose any sleep over this until Cygnus comes to the FM3. It's less polite than Ares, especially in the low end where the omnipresence resides. When it comes I'm sure you'll find it more AITR and can then move on to debating the 'feel' versus your real amp ;)
IMHO it feels good man !
P.S. on the Axe-Fx III Cygnus 16.0 changed the game, 16.1 upped the ante.
 
MrPond said:
Haha no problem :) Yeah, everything is set to SS Poweramp + Cab.



Maybe ... i think so, too.



I think my question makes sense, because it's what i hear (and my band buddy, as well)
The sound of the FM3 is more in a beam compared to my tube amp. Almost the same sound, equally leveled.
It it what it is - because the cab is the same constant in this setup, the "issue" has to be the FM3 or the power amp.
My question was what the issue can be - so, i have to disagree - i think (almost) every question is a valid question if something is unclear ;)
I'm not a physicist, only a musician ..

Another example: If i stand behind my cab, my tube amp sounds "thicker" (not bassy, like ... more "beef").
Again - hard to describe! But it's what i can reproduce on different cabs in different environments.
Click to expand...
If your tube amp has a preamp out or an FX send, you could try running that into your PS170. That will at least tell you whether it's the PS170 or FM3 that is making the difference you don't like.
 
Maybe just me but 170 watts at 4 ohms isn't even enough to push a cab into resonance imo unless it's like a single 12" 50 watt speaker. Sure you can crank it up so the levels are close, but with no power there is no weight to it.

When using solid state power amps, driving full range FoH, I was taught that you need 3x the speakers handling 'at minimum' to properly drive them, so a 300 watt cab is going to need 'at least' a 900 watt power amp (that's RMS not peak) to be comparable to a 100 watt tube amp, for example. We usually used double recommended as low frequency eats your power up exponentially as you bring it up with solid state.

I gigged an Axe-Fx II into a Behringer EPQ2000 into a Marshall 1960B for a couple years, it delivered the goods. I followed the same method of power handling.

That's my experience.
 
Thanks for all the feedback, guys! I really appreciate it!
My todo list 👍
  • I'll take some time to try out different speaker impedances - i took the citrus 4x12 because i play a PPC412 but of course, i'll take a look at all of them :)
  • amp's fx send to my power stage to "eliminate" "issues" with my poweramp
  • check volumes with a decibel meter
  • take a fresh look (ear? 😅) with Cygnus

Thanks for all your ideas!!
 
ChainOfThought said:
Took the words out of my mouth. Search around the forum for cab resonance. Cliff had a really good thread on it in the tech notes area a few years back.

edit: https://forum.fractalaudio.com/threads/about-matching-your-cabinets-resonant-frequency.79816/
Here it is
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LT also did a great video about two years ago explaining resonant frequencies and how SS amps differ from Tube amps in their relationship with speakers requiring you to adjust resonant frequency curves in the FM3 when using SS amps... That LT is a genius. Thanks again Leon for your endless and easygoing support of this community!
 
ToneDriven said:
LT also did a great video about two years ago explaining resonant frequencies and how SS amps differ from Tube amps in their relationship with speakers requiring you to adjust resonant frequency curves in the FM3 when using SS amps... That LT is a genius. Thanks again Leon for your endless and easygoing support of this community!
Click to expand...
Interested. Do you or @2112 remember the video name?
 
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