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A Faster S.S. Head?

S

shoot-r

May 26, 2007
4,107
3,849
Illinois
#1
I've got three Solid State heads.
A "old" G.K. 800...
A G.K. MB2-500...
A Ampeg PF-500...
One head at a time, played through the same 210 cabinet and using the same Fender Jazz bass, no effects pedals.
Two of these heads "feel fast" in their response.
One feels slow in compairson to the others.

Is this just my imagination?
 
#4
Windreaper said:
Let me guess, the GK heads felt faster? It is all about how the amps are voiced. Mids are generally perceived as fast and lows as slow. It is all psychoacoustics, though.
Click to expand...

Yes sir, the GK-500 feels fastest and brighest. The GK-800 seems fast, but underpowered when compaired to the other two. The Ampeg PF-500 just sounds plain ole' "GOOD", but feels slightly slower in it's response when playing a muilty-note, fast, bass line when compaired to the GK-500.
Gallien-Krueger's catalog states, "the quick, punchy power sections that GK bass amps are known for".
I always took that as advertising fluff...to my ears it's not.
 
#5
shoot-r said:
Yes sir, the GK-500 feels fastest and brighest. The GK-800 seems fast, but underpowered when compaired to the other two. The Ampeg PF-500 just sounds plain ole' "GOOD", but feels slightly slower in it's response when playing a muilty-note, fast, bass line when compaired to the GK-500.
Gallien-Krueger's catalog states, "the quick, punchy power sections that GK bass amps are known for".
I always took that as advertising fluff...to my ears it's not.
Click to expand...

No sir, GKs are among the quickest responding amps out there.
 
#7
Catbuster said:
No sir, GKs are among the quickest responding amps out there.
Click to expand...

+1...

This is what my ears are tellin' me also.......whatever it's called, the GK-500 feels faster/clearer/more defined on a loud, fast, run.
But, to my ears, the PF has the mojo in the over-all tone department.
I'd have trouble choosing between the two if I could only keep one.
 
#8
some amps are faster than others? maybe the damping factor of the gk fits that particular speaker better. they would have to be adjusted with an analyzer for the same frequency response to make sure the tone isnt swaying your ears. a fast double bass drum track would show the difference well and because it is more consistent may show clearer results. whats the cabinet?
 
#9
okcrum said:
This. You don't hear the less than xxx microsecond delay through the amp.
Click to expand...

I would have agreed with you if it was just me hearing this.
I've A/B'ed the two heads at rehearsal, others hear it also (or maybe I've got them convinced it's there).
The wife hears it also when I'm at home and in the quiet of our family room.
My ears have also noticed this phenomenon with some all tube heads.
 
#10
staindbass said:
some amps are faster than others? maybe the damping factor of the gk fits that particular speaker better. they would have to be adjusted with an analyzer for the same frequency response to make sure the tone isnt swaying your ears. a fast double bass drum track would show the difference well and because it is more consistent may show clearer results. whats the cabinet?
Click to expand...

Avatar Neo 210 cabinets, 8 ohms.
Loaded with Eminence's cast framed Neo's.
 
#11
shoot-r said:
I would have agreed with you if it was just me hearing this.
I've A/B'ed the two heads at rehearsal, others hear it also (or maybe I've got them convinced it's there).
The wife hears it also when I'm at home and in the quiet of our family room.
My ears have also noticed this phenomenon with some all tube heads.
Click to expand...

I don't disagree that you hear something. It's just not the signal delay through the amp. You could argue for damping factor producing some effect if it were very low (like 50 or less) but Windreaper is more likely on it. I can hear something like you describe when I play with the EQ on my amps.

The other big factor is the type of filtering/EQ design used. Filter response can definitely be audible in some cases. Class D amps also have an L-C filter at the output of the amp. This can lower the damping factor relative to Class A/AB designs.
 
#13
okcrum said:
I don't disagree that you hear something. It's just not the signal delay through the amp.
Click to expand...

+1

I think "fast" and "slow" are poor terms for describing speaker performance, and even poorer for describing amp performance. Considering that even a "slow" 18" woofer can reverse direction more than 1000 times in one second, these are amounts of time that can only be perceived in certain contexts. On the other hand, we are quite sensitive to differences in frequency.

If you're describing frequency response or tone, better to use terms like bright, dark, treble, deep, warm... etc.

IMO, of course.
 
#15
Actually, on thinking about it a bit, what shoot-r is more likely hearing is the group delay differences in the two systems. It's not specifically a fixed time delay, but rather the incremental change in phase with respect to frequency as you sweep through the spectrum. It's defined as dø/df for those who'd like to explore further. Different filter topologies have different group delay characteristics, and if you're listening, the speakers are part of the effect too.

EDIT: It's also important to remember that the actual value of group delay is not a single number, except in a perfectly phase linear system. Example: a circuit composed only of perfect resistors.
 
#16
Just wondering since I've NO idea what I'm talkin' about.
With both the GK MB500 and the Ampeg PF500 using a Class D power amp the difference seems to be in the preamps.
The Ampeg has a Mosfet preamp, from what I can find the GK is straight solid state.

Would the Mosfet design give the filter topologies okcrum is talking about?
 
#18
fast and slow are not terms to use here.

I'm not denying that you're hearing some difference, but I don't know what that is given the fast and slow terminology.

Harmonic content?

Differences in the way the amps interact with the cabinet?

Room acoustics?

Also, I *think* GK amps have a built in phase-flip, so the speaker moves IN instead of OUT.

Maybe that's what you're hearing?
 
#19
adbass said:
Also, I *think* GK amps have a built in phase-flip, so the speaker moves IN instead of OUT.

Maybe that's what you're hearing?
Click to expand...

Virtually all amps invert phase at some point during their gain stages. Whether the signal exits the amp phase-inverted or not simply depends on how many inverting gain stages the signal goes through as it is amplified. To our ears, it matters not one bit if the signal that exits the amp is phase-inverted or not at the speaker terminals--the concept of "absolute phase" is irrelevant since this is an AC signal.

Furthermore, some speakers (like certain JBL's) are backwards compared to the conventional speaker movement of today--the cones of those JBL's move backwards when a + signal is applied to the red terminal. (JBL Technical Notes, Volume 1, Number 12B)
 

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