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Flat response Class D amp?

#41
hintz said:
This/\!! IIRC, flat on a markbass is something like 9:00 or 10:00, but definitely not at noon!! I wish I would've known this when I tried them out, I might've dug the sound better!?
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On the Markbass LMII and LMIII, these amps are are maximally flat with the bass, lo mid, hi mid, and treble controls set to 12:00 and the VLE and VPF filters turned fully counter-clockwise (7:00) where they have virtually no effect.
 
#42
figuredbass said:
On the Markbass LMII and LMIII, these amps are are maximally flat with the bass, lo mid, hi mid, and treble controls set to 12:00 and the VLE and VPF filters turned fully counter-clockwise (7:00) where they have virtually no effect.
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Hmmm, I played through one of the MB combo amps 5 years ago for 2 months (dont remember which model), and I never gelled with it and was informed after that flat wasn't noon, but hey, I could be just dead wrong in which case I stand corrected!! Either way, I wasn't impressed with the tone by any stretch and with the knobs at noon it sounded like there was way too much midrange, so it got returned...
 
#43
hintz said:
Hmmm, I played through one of the MB combo amps 5 years ago for 2 months (dont remember which model), and I never gelled with it and was informed after that flat wasn't noon, but hey, I could be just dead wrong in which case I stand corrected!! Either way, I wasn't impressed with the tone by any stretch and with the knobs at noon it sounded like there was way too much midrange, so it got returned...
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+1 You do have a point. I actually measured it on an oscilloscope, and while those noon settings are maximally flat, there is still a very slight broad band rise around 1K Hz remaining. It's only about +1 dB, but because the rise is relatively wide, this, plus the fact that the amp is also adding a small amount of harmonic coloration, definitely makes it sound more mid-forward than a truly neutral amp. I found the extra mids a bit excessive myself since I had already worked my bass's EQ and coloration around more neutral amps.
 
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#44
figuredbass said:
+1 You do have a point. I actually measured it on an oscilloscope, and while those noon settings are maximally flat, there is still a very slight broad band rise around 1K Hz remaining. It's only about +1 dB, but because the rise is relatively wide, this, plus the fact that the amp is also adding a small amount of harmonic coloration, definitely makes it sound more mid-forward than a truly neutral amp. I found the extra mids a bit excessive myself since I had already worked my bass's EQ and coloration around more neutral amps.
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I think this is where the reputation comes from. My first real amp was Markbass and it just sounds normal to me.
 
#45
Doner Designs said:
I think this is where the reputation comes from. My first real amp was Markbass and it just sounds normal to me.
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Really, I haven't been impressed by any of the newer amp companies that I've actually *tried*(and by newer I mean over the last 15 years or so) like Markbass or Eden, both brands left me under whelmed!! But then again maybe I'm a little biased or just too used to some older amps??

I try to find "flat" by matching the amp the the acoustic sound of the bass right next to my ear(volume off of course;)), and then adding character or real tone and I believe you can get at least close to this with most good amps!! I never assume dials at 12:00 are flat, and also why I use a fEARful, I want as little color from the cab as possible

As far as class D amps, I'm intrigued by this new mesa subway amp, but mesa has been around awhile too so...
 
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#46
tombowlus said:
We didn't do the "optimally flat" measurements and settings back in issue #1 (when we reviewed the LMII), but Invalid Link Removed.
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Thanks for this, Tom. Now, I haven't been able to get it to load on my supposedly "smart" phone, but I appreciate it just the same! (Will check it out next time I'm out and about with my laptop.)
 
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#47
agedhorse said:
I should have been more specific, I was referring to the use of EQ to alter frequency response as had been mentioned earlier).

Harmonics is the addition of related frequencies, rather than eq altering the amplitude of existing frequencies.

Dynamics alone really does not translate to the frequency domain (in the traditional sense) because it is a frequency independent term. Now applying dynamics along with harmonics alter both the real and imaginary part of the equation and not necessarily together. In fact, the equations can get a lot more complex in a hurry. This is one of the big challenges to mathematically describing such complex behaviors successfully in amp emulations. Emulating the basic tones and frequency responses is pretty straight forward in modeling products, but emulating the complexities, and the feel that goes along with this is much more complicated. The complexity increases exponentially with the more mechanisms that need to be accurately described.
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Yes, there are two approaches to replicating - mimic frequency/amplitude/phase response or model the underlying physics. I believe you when you say that it gets complex quick, especially if the frequency response changes with amplitude or with history (hysteresis).

JimmyM said:
Ya, was going to say that if amplitude, phase and frequency were everything, then how come nobody's successfully duplicated tube amps in every way with solid state? :D
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As I said, the math says we can fully express any signal in either the time domain or the frequency domain so in that regard, yes it's all just amplitude, phase and frequency. That only works if I know the signal end-to-end before hand which we don't so, in the practical sense, the frequency measurements at any given time are an approximation and don't capture the dynamics (change in response with amplitude, history, or other conditions e.g. temp). I've heard some pretty good replications in solid state (Peavey Transtube is the one I've used) and all-digital emulations (Revalver) but I don't have much time playing on tube amps so I can't talk to how well they do - some people seem to love 'em some people are still left wanting.
 
#48
Rob22315 said:
As I said, the math says we can fully express any signal in either the time domain or the frequency domain so in that regard, yes it's all just amplitude, phase and frequency. That only works if I know the signal end-to-end before hand which we don't so, in the practical sense, the frequency measurements at any given time are an approximation and don't capture the dynamics (change in response with amplitude, history, or other conditions e.g. temp). I've heard some pretty good replications in solid state (Peavey Transtube is the one I've used) and all-digital emulations (Revalver) but I don't have much time playing on tube amps so I can't talk to how well they do -
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I figured as much :D I play tube amps all the time and I can tell you with 100% certainty that an emulation that duplicates everything about tube amps does not exist. At best they sound like recordings of tube amps being mic'ed.

some people seem to love 'em some people are still left wanting.
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That's a valid feeling but beside the point.
 

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