Posts by Klappy

Sharry, I'm only suggesting that this be applied to the monitor EQ, so the audience has nothing to do with this. It only needs to be adjusted for one person, the player. But I need to state this point again because it is important. The rate at which to need to adjust the EQ at a given frequency to compensate for volume changes is independent of the starting volume. The FM and ISO curves show this very clearly if you know how to read them.

Here is actual ISO226-2013 data plotted in a different way. This is updated FM data basically.

Note that if there were no FM effect, all these line would have a slope of 1 and there would be no offset on the Y axis (the most basic y=x linear equation). This data tells us three things:

• The y-axis offset shows that we need to supply different levels of power at different frequencies to appear that the sound is equally powered at all frequencies. (weighting).
• At a given frequency, the relationship between power output and power perception is roughly linear as shown by the good fit to linear regression lines.
• Because the slope differs for each of these lines, we see that the power output will need to be adjusted at different rates at different frequencies to make the EQ of the sound appear constant. But since it is linear across the entire range, we don't need to know absolute values to adjust for loudness changes. We only need to know the rate at a given frequency.

And finally, since these are all linear relationships, note that if we have (x1, y1) and (x2, y2) at a given frequency, linear interpolation between these values wil properly compensate for the FM effect. The user determines (x1,y1) and (x2, y2) for all drequencies when he/she EQ's at two different volumes (two point calibration).

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Quote from viabcroce

Well, if you want to approach the issue scientifically, reasons are right there: how an SPL variation influences the "average ear" also depends on the absolute SPL value.
IOW, F-M curves are parametric: the percent perceived level increase\decrease of a given frequency depends on the absolute level it changes from.

That isn't correct, and maybe it is where some are getting caught up. The beauty of using the relative logarithmic decibel scale is that you can compare relative values without an absolute reference. You only need to state a reference value to convert a dB measurement (a ratio) into an absolute value. Adding +3dB at 1W output and adding 3dB at 100W output are dramatically different amounts of added power, but the ratio of increase to the original signal is exactly the same in both cases. This is exactly why we don't need to know the level of a fader to add 3dB of boost of EQ to it. Now all we need to know to make this idea work is if the required boost level at a given frequency to maintain equal tonality at a louder volume is always constant in terms of dB.

So here is an example to explore that last question if you are all still following me and I haven't outlived my welcome...

Check out the FM curve on Wikipedia or where ever. Let's start at the 20dB SPL isophon. Assume we have the amp EQ'ed perfectly at this really soft level. Now we want to play at 20dB louder and still sound the same. We need to add about 10db of SPL (proportional to output power) at 100hZ, 20dB at 1K, and 20dB at 5K. But now note that if you were to jump from the 60 dB isophon to the 80dB line, you would be changing by the same relative amounts (dB's) for that jump too. It didn't matter where you started from. You need to add 10dB to the bass, and 20dB to the mids and treble to make the sound be perceived as 20dB louder across all frequencies. The isophons don't always jump equally at every frequency over the entire range, but it is pretty darned linear as far as our chaotic world goes.

And of course the FM curves don't tell the whole story. Everyone has experienced compression drivers getting nasty at higher volumes. This too can be compensated for by gradually and proportionally reducing treble output as volume increases.

And regarding FM being only an average for human perception, that doesn't matter either, since the user will be setting the two calibration points themselves based on thier own peeception. All that matters is that the jump from one isophon to the next is roughly constant at a given frequency. If you needed to add +10dB of bass from the 20dB isophon to 40, +15 from 40dB to 60dB, and +5 from 60dB to 80dB, this would not work because you WOULD need to know the SPL your actual cabinet was putting out to make the proper jump. As long as the jumps at a given frequency are approximately the same, then we don't care how loud the cabinet is when we change volume.

Does this make sense? I have a BS in Engineering, so some stuff that might seem obvious to me might not be to all. I'm trying to explain my point the best I can, but I can't always tell if I'm doing a good job.

You guys are making this way more complicated than it needs to be. There is no reason to know the power output or SPL levels or have any reference to the FM curves within the KPA. The user simply needs to EQ the monitor at two different volumes to his/her preference and interpolate the EQ values in between. The interpolation function needs to be chosen such that the morph works correctly. The KPA monitor volume goes from 0 to 10. If this value already tracks SPL linearly than you just need to do linear interpolation on the EQ and you are done. If not, you need to find a function that linearizes the relationship. This can be done just once with either math or measurements by Kemper. Since the KPA already has interpolation functions built in (morphing), the whole process of implementing this shouldn't take more than an hour unless there is some architecture issue in the way.

I have no idea how they sound, but the Bose L1 and similar line array speakers have amazing dispersion. The L1 compact is only $900.

Reading Ingolf's reply makes me think that I misunderstood Sharry's reply. So I guess you are proposing that there are other "loudness" factors besides volume? I agree 100%. The frequency response of speakers is proportional to volume. They also distort at high volumes. However, these effects manifest somewhat smoothly, if not entirely linearly. This is one of the reasons I proposed having different response curves available.

I think that dismissing this as not possible because there isn't a perfect mathematical function that can track EQ compensation to volume is a case of perfection being the enemy of improvement.

Sharry, "loudness" as used here is an English idiom for volume compensating EQ, not for the actual volume. I'm not sure what the German word for it is, but it is the same as the button on a stereo receiver that adds bass and treble to the sound to add the same "excitement" as you get from playing music loudly. For me, I really need a "softness" EQ that takes off some bass and treble at loud volumes to make it sound more like the sounds I dial in in my living room. I have much more time to tweak at home than I do at rehearsal.

The only difference to the normal monitor EQ that I am suggesting is that it be automatically variable so you don't have to program multiple compensation EQ's for different stage volumes. I like simplicity .

The FM curves themselves aren't linear or log at SPL=f(frequency), but for a given frequency the phon=f(SPL) relationship is roughly linear. Say that you need to boost bass by 6dB and treble by 3 dB at low volume to maintain "loudness". By the approximately linear phon to SPL relationship, you would need to boost bass by 3dB and treble by 1.5 dB at the halfway point of loudness perception. This would be simple to automate. Each frequency tracks linearly, but at different slopes. To see what I mean, look at the FM curves and note that at a given frequency the steps between phons are about the same distances, but the steps at different frequencies are different.

So in simpler terms, I'm suggesting a variable loudness feature that could be customized for a given listener and cabinet. Program your monitor EQ at high and low volumes, and the KPA will interpolate at any volume automatically. This should work pretty well with linear interpolation, but I suggested other curves to allow for personal preferences. I often do my programming at low volume, then the sounds get harsher as I turn up the volume. It would be nice to have an EQ that was gradually and proportionally applied as I got louder.

It would be nice if the Monitor EQ (ideally parametric ) could be linked smoothly to the Monitor output level in order to compensate for loudness effects. This would allow for sounds to remain more consistent over a wider range of volumes (sleeping wife, wife not home, acoustic gig, rehearsal, club gig, stadium gig...) You program an EQ at low volume, and one at full volume, and the parameters morph smoothly in proportion to the volume. Maybe add the ability to do linear or log functions as required.

PMG was the first concert I ever saw. It was at Princeton University, probably around 1981. It was either their first gig or first tour with Naná Vasconcelos. There were probably only around 30-50 people in the audience. That show made a big impact on me going forward. Glad to see him in the family now!

Quote from Michael_dk

This is one of these "if the income from your studio business can pay for this, then consider getting it". If it can't - then you probably have no reason to buy it, except as a "toy" (which is fine, by the way)

That's a good rule for almost any musical purchase. I actually can't think of an example off the top of my head where it doesn't apply. It's a rule that keeps me grounded. There is one other rule I use that doesn't apply here. Since I own/buy/sell a lot of vintage guitars I always ask myself about potential investment return. I've lost so much money on studio gear, and made a fair bit on guitars/basses.

There's no problem leaving the power amp on if nothing is plugged into it. The amp is Class D, which is fine with an infinite load (open). If you aren't using the amp frequently though, you can turn it off from the output menu.

Regarding cab sim on mains but not monitor, I think so but I'm not sure. Someone more enlightened can help there.

The internal amp has plenty of power, even when driving my 4 ohm bass cab. You won't see any appreciable performance difference using an external amp. Also, there is no point using a tube amp unless you plan on over-driving it, but there is no point doing that with the Kemper. And the convenience of the built in amp can't be beat.

It's all Kemper for me these days, for bass and guitar. I'm in the process of making a "Kemper Kombo" that will just need a power connection to be ready to go. The remote and all my straps, cables, tablet, etc will be stored in the cabinet. After a gig, I can wheel it into my living room and have it set up in less time than it takes to boot up. The whole rig should weigh less than a 2x12 when I'm done.

I'll start a thread about the combo when I'm a little further along.

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One of these:

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1983 Ibanez Roadstar II RB650. It was my first bass, so there was no way to really appreciate how good it was at the time. I sold it in 1986 and have regretted it ever since. I don't think I had a better sounding P-Bass until I got the '64 in my avatar. I did wind up buying another a few years ago, but the neck on that one is a little wonky. The tone is all there though. Major bark in this bass. It falls into the category of "this shouldn't work". The sunburst is fake. The top and back are 2mm thick plastic laminates with printing on them. So much for theory.

@OhG, that was my same experience. The Digitech performed noticeably better on my clean guitar. If I recall, it wasn't so much the latency, but the DT seemed to lock in better, with less glitches and warbles. In a live situation, the KPA is still good enough for the simple strumming in my particular application, but I imagine the overall mix would sound cleaner and tighter without the chaos.

Quote from nightlight

This is really interesting information. The pitch fork is better than the Kemper transpose? And the Whammy DT is even better? If you have the pedals would you mind posting some clips? Would appreciate it, thanks!

The difference isn't big enough to get exited about. They are both glitchy and delayed at a -5th. If the Kemper transpose and Pitchfork were both similar pedals, I'd use the pitchfork. But currently I use the Kemper because the difference isn't big enough to overcome the inconvenience of an extra pedal. Regarding the Whammy DT, I don't own one but I compared it directly to the Pitchfork at a -5th.

I actually push it a bit. I use it on guitar to drop to A for a song recorded on a baritone. It's glitchy, has latency and warbles, but it's still useful for my rhythm strumming. I also own the pitchfork which is a little better IMHO, at least for a 5th drop. The best one I played was the Whammy DT, but it was too large for my board. That was noticeably better than both Kemper and the EH.

Improving the Kemper's Transpose function would be very near the top of my development wishlist.

I found a decent example in my library. This is my '66 B15 that I profiled "clean", and then added a little gain to afterwards. The bass is a $179 Squire P/J with both pickups on full for the Rick "boing". I'm not sure what version of the Jaguar you have, but it shouldn't be way off (unless it's the single soapbar one). Here are some samples of this profile using songs that I'm pretty sure were originally played on Ricks.

The profile is now up on Rig Exchange as "Rickish bass"

I haven't run across a free bass profile that I use for crunch that didn't need a bit of tweaking unfortunately. Some of the crunchy guitar profiles sound nice, but need more low end. Blending in some clean bass can help some, as does swapping to a bass cabinet model or adjusting the LF of the guitar cab model. Most of the bass profiles I use now are home-brews, and I'm not using much crunch these days for my basic sound. I do remember a Bassman 100 profile that was in the neighborhood though, maybe the one that came as a stock profile. I used that one briefly for crunchy rock.

I've been meaning to post a few bass amps on the rig exchange but haven't gotten around to it, so maybe it's time.

Ricks have a natural crunch to my ears, or at least the crunch is implied by it's barking sound. I'd try a little bit of gain/OD. Geddy Lee gets a pretty good Rick sound out of his JBass on Moving Pictures. Lot's of crunch there.