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A Faster S.S. Head?

#81
I know what you're talking about b/c I go through a lot of amps that are pretty comparable and I would say stuff like the GK and then my M9 feel like you're getting a "faster" response, even though that's not the technical response I'm sure. It has to do with the voicing of the amp, not "how fast" can an amp process your sound which they all pretty much do it immediately.
I kinda refer to it as a more immediate or direct attack. A GK will give you maybe a faster "note bloom" than like the Mesa M-Pulse 600 which feels a little "slower", with a bigger, rounder bottom end. This is the reason a lotta people who didn't prefer the older "M-Pulse" style Mesa stuff really like the Carbine line.
 
#82
JimmyM said:
It may seem strange to some, but with every rig I've ever used, I hit a note on the bass and the sound comes out of the speakers immediately without delay.
Click to expand...

Do you want me to search for times when you said that even if your ears couldn't tell the difference between all tube and SS or Hybrid, your hands could, because all tube Ampeg heads "FEEL" different than anything else on the market? Cheers.
 
#83
Carvin may have an explanation for "slow"

Go to page 10, marked at "53" for their power amps in their catalog
[Invalid or Expired Link Removed]

Look at the "Kick Drum Test"
They exaggerate a bit, but after an initial note, the power supply needs some time to recover to allow the next note to come out as loud.

Maybe this is "Fast" or "Slow"?
Guitar amps due this as sag, and guitar players play around it.

Might as well add "Fast" or "Slow" to the adjective list to describe bass amps. Who care's. It's not much different than using "Feel".

I rather see measured differences published but that's never going to happen for bass amps.
 
#84
Two channel oscilliscope, a mic, and a function generator could get some data. Put channel one of the scope at the input to preamp. Put the mic at the speaker. Put the second channel of the scope on the mic output. You could also put a current probe on the current going to the speaker and feed it into a third channel. Once this is in place, one could feed the function generator into the preamp and measure the response time and also characterize frequency response, and how everything changes with output level, etc. It would be interesting to feed a pure sine wave cycle into the preamp and see how the speaker responds and how well damped the response is (any ringing after the sine way cycle is thru).

I have spent enough time fixing things to believe that emperical observations are usually superior to mathematical calculations. While physics and math can be great tools, they always needs to be verified.
 
#88
HUnt49 said:
And I think Kjung has nailed, in poetic terms, what we are hearing.

I submit that the term "bappy" should be permanently lodged in the Talkbass lexicon.
Click to expand...

Maybe it will be. I'll certainly take "bappy" over "fast". We have a lot of odd and/or ambiguous terms to describe sound. Nature of the beast... I accept that. But I have a unique dislike of "fast" and "slow" because they reinforce misconceptions about how speakers and (to a lesser degree) amps work.

Ken's description is helpful. His focus on the attack of a note makes sense in terms of frequency response. Since the attack has more high-frequency content than the sustained note, a rig with stronger mid-HF response will reveal more attack.
 
#89
OK ready to be called "full of it again"......
Poorly designed or good designs needing attention can seem slow. Speaker/cab combos can also. I could hear the attack difference if I put a 12AX7 in place of the 12DW7 in my old V4B. I had a pair of JBL D-140Fs in an acoustic cab that I had to play ahead of, Altec 421As took care of that. I am the bands metronome, I have always been sensitive to timing. That's enough to be called crazy about so..........
 
#90
seamonkey said:
Carvin may have an explanation for "slow"

Go to page 10, marked at "53" for their power amps in their catalog
[Invalid or Expired Link Removed]

Look at the "Kick Drum Test"
They exaggerate a bit, but after an initial note, the power supply needs some time to recover to allow the next note to come out as loud.

Maybe this is "Fast" or "Slow"?
Guitar amps due this as sag, and guitar players play around it.
P
Might as well add "Fast" or "Slow" to the adjective list to describye bass amps. Who care's. It's not much different than using "Feel".

I rather see measured differences published but that's never going to happen for bass amps.
Click to expand...


+1

Voltage sag is a quality, especially in tube amps or those trying to model/mimick tube amps, which is what they're all trying to do, mimick tube amps.
 
#92
shoot-r said:
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?
Click to expand...

Thanks everyone for your responses...

I've spent the last week going between the PF500 head and the GK MB-500 head, love em' both, gonna keep em' both. But after a week of knob twisting I still hear the same thing as I originally posted.
I now think instead of saying that one head "feels fast" I should have maybe worded it as, "one head, on a fast multi-note bass run seems to "blur" the notes, with the other head the notes exit the speakers with distinct separation between them."
 
#93
Just to be clear, DavePlaysBass is not incorrect in estimating 2 ms filter delay in post #44. That's a lower limit, but delay can go as high as 20-25 ms depending on the filter design. All the numbers for phase delays in filters are dependent on the type and Q of filter chosen.

That is all. ;)
 
#94
okcrum said:
Just to be clear, DavePlaysBass is not incorrect in estimating 2 ms filter delay in post #44. That's a lower limit, but delay can go as high as 20-25 ms depending on the filter design. All the numbers for phase delays in filters are dependent on the type and Q of filter chosen.

That is all. ;)
Click to expand...

That's not quite delay though.

There will be phase shift but that's not the same as delay, because with one filter you will have phase lag and the complimentary filter will have phase lead but we know from physics that you can't have a negative delay that a phase lead would APPEAR to have because that would be equal to the signal happening before it happens.

Also, in filter response, just because you have a phase shift, you must also look at what is happening to the amplitdue... who cares what the phase shift is when the signal is 20dB down... what IS important is what's happening to like amplitude signals.

As a reality excercise, 20 mSec of "delay" (due to appearant phase shift) would equate to what filter topology and at what frequency. I think you will find it falling outside of the audio band by the time you achieved enough phase shift within even 12dB of the initial signal. Now, what happens when you invert the filter and the phase shift flips? Did you just "create" 40mSec of time due to the leading phase?
 
#95
agedhorse said:
That's not quite delay though.

There will be phase shift but that's not the same as delay, because with one filter you will have phase lag and the complimentary filter will have phase lead but we know from physics that you can't have a negative delay that a phase lead would APPEAR to have because that would be equal to the signal happening before it happens.

Also, in filter response, just because you have a phase shift, you must also look at what is happening to the amplitdue... who cares what the phase shift is when the signal is 20dB down... what IS important is what's happening to like amplitude signals.

As a reality excercise, 20 mSec of "delay" (due to appearant phase shift) would equate to what filter topology and at what frequency. I think you will find it falling outside of the audio band by the time you achieved enough phase shift within even 12dB of the initial signal. Now, what happens when you invert the filter and the phase shift flips? Did you just "create" 40mSec of time due to the leading phase?
Click to expand...

Yep. I was referring to the 40 Hz low pass filter example, which is why the numbers seemed large. I guess I tried to simplify too much. But 20 ms would be about 270º (or -90º) of phase shift at that freq. That's a typical 3rd order Butterworth phase response, to answer your question.

Of course, you don't "create" any time in the high pass case. It's simply that the arithmetic sign of the transfer function for phase is negative. What you really have is shown in the Butterworth case above. Phase shift increasing linearly with frequency is in fact equivalent to time delay. But that's a Bessel filter, no? And you already know that a 180º phase shift is not the same as inverting the signal either, the classic example being a sawtooth waveform.

You'll get no argument from me about considering the amplitude response of the filter. That just seemed outside the scope of this (getting off topic) discussion. In some non-audio cases, you knowingly take a lot of attenuation to get something else, like when you want a 250:1 delay to rise time ratio in a pulse delay line. These cases are rare, though.
 
#97
To continue the EQ side of the equation... There's more at play than just the amp.

I think the bass itself, and it's inherent EQ, affect the perceived "bap" factor, so individual's observations about amps are affected by variables, aside from being subjective.

There's a world of difference in the perception of note response between my active Warwick $$ and my passive j or p -- even with the Wick in passive mode. Love those mids. That bass is one that makes me almost understand the guy who said the notes jumped out before he played them - instantly there, no bloom.

I presume that the EQ voicing is a factor - but is the active output level also a contributing factor for the amp?

Of course, the OP is using the same bass (I assume), so this is a sidelight...
 
#98
HUnt49 said:
To continue the EQ side of the equation... There's more at play than just the amp.

I think the bass itself, and it's inherent EQ, affect the perceived "bap" factor, so individual's observations about amps are affected by variables, aside from being subjective.

There's a world of difference in the perception of note response between my active Warwick $$ and my passive j or p -- even with the Wick in passive mode. Love those mids. That bass is one that makes me almost understand the guy who said the notes jumped out before he played them - instantly there, no bloom.

I presume that the EQ voicing is a factor - but is the active output level also a contributing factor for the amp?

Of course, the OP is using the same bass (I assume), so this is a sidelight...
Click to expand...

+1 Just like there are 'fast sounding/feeling' amps (based on my interpretation of that term posted above), there are 'fast' sounding basses and cabs (and players who have good chops and a strong attack playing close to the bridge).

The entire signal chain impacts this sort of perception of the leading attack/response of each note.
 
#99
The basic point I was trying to make is that while something may look like a time delay, and act like a time delay, it's more of a change in the point of reference of time. The effects of phase with respect to time certainly is important when considering any other signal paths involving the same (or similarly processed) signal.

As another way of looking at this (using this highly smplified example, ignoring amplitude), say you use a HPF and lag the voltage by 180 degrees but then apply a LPF and then lead the voltage by 180 degrees (but you can't create time) you are back to 0 degrees. If you can't lead time, you can't cancel real time delay.

AD43_09_FIG-03.jpg (from AD article: Invalid Link Removed)

This is not unlike the particle theory and wave theory duality that occurs in the analysis of light energy. It depends on how you look at the problem as to which solution makes sense in context.
 

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