Bose was (as usual) early into the game of self powered loudspeakers, and now has the remarkable PAS system.

All the self-powered professional speakers with which I am aware use *lots* of processing inside to protect all the bits, and to do other magic such as time alignment, frequency shading, crossing over, and etc.

I also note that "gain staging" is an extremely important topic for the PAS. Whenever a feedback or low volume issue is raised, a Guy-at-Bose makes sure to discuss the proper "gain staging" of the system. Now, with a normal PA with no gizmos running, attention to the gain structure will improve signal to noise ratio, but doesn't have much to do with gain before feedback, in my experience, at least. (I spend no time anywhere near the edge. Therefore, I may have a few things to learn here. Intellectually speaking, only, of course, as higher volume levels than I use are of no interest whatsoever to me or my ears, and I use good gain structure in my set-ups anyway.)

Having said that, the only reason that I can think of for the gain staging of the PAS to be so important is that there is some tricky compressing/limiting (and maybe more) going on to 1) protect the speaker and 2) provide some other performance benefits.

And what the devil do those presets do, anyway? If I want a Shure Beta 58 sound, shouldn't I use a flat preset? However, universally, everyone recommends a (presumable non-flat) preset.

The developers of the presets are pretty coy about them. Something about just noodling around until things sound better - but what is happening in there? Do the presets remove the most egregious frequency response perturbations exhibited by, for instance, a Beta 58? Or make a bigger, better, badder Beta 58? Or what?

Is it possible for anyone to discuss the internal workings in somewhat greater detail? Please? Pretty please?

Mike

With credit to Alex De Anda.
Original Post
Let me try and help. We have no secrets we're hiding but there are many questions left unanswer (and unasked) I'm sure:

quote:
Having said that, the only reason that I can think of for the gain staging of the PAS to be so important is that there is some tricky compressing/limiting (and maybe more) going on to 1) protect the speaker and 2) provide some other performance benefits.


It's an integrated system and making the most out of the available wattage means getting gain staging correct. Also, input sensitivity can lead to feedback even at low volume levels. Good gain staging makes sure that everything is working optimally and it's pretty easy to do.

quote:
And what the devil do those presets do, anyway? If I want a Shure Beta 58 sound, shouldn't I use a flat preset? However, universally, everyone recommends a (presumable non-flat) preset.

The developers of the presets are pretty coy about them. Something about just noodling around until things sound better - but what is happening in there? Do the presets remove the most egregious frequency response perturbations exhibited by, for instance, a Beta 58? Or make a bigger, better, badder Beta 58? Or what?


Think if it this way, if you work at Shure, Audix or any company making microphones you have no clue what speaker your customer will use to reproduce sound with your mic. So you voice it for a "best fit" system (or systems) and hope the market (or a part of it) agrees with your deicsion(s).

Now, imagine you knew EXACTLY what speaker your customer was going to use your mic with. Let's say, a Cylindrical Radiator(r) speaker Smile. Well, then you could voice the mic to create a very nice response.

That's what we can do with presets. We can create an EQ curve that attempts to make the mic sound very natural since we know how the speaker and mic will work together. It's that simple.

The good news is that 00 is flat which means the mic will sound like it is "supposed" to sound (according to the mic manufacturer).

Then there is the artistic choice. If you like the SM58 preset for an OM5 ... well, go for it. I've heard a few guitar players say they love the Accordian preset ... go figure.

I hope that helps to de-mystify presets. No voodoo or making things bigger and badder. Just choices. You can use the Bose choice (mic preset) the mic manufacturers choice (flat) or your own (try your voice with the accordian preset). Oh, and there's the 3-band EQ.

Steve

PS Is that a good start to the discussion?
MTM,

About presets. I'm talking kick drum here, but I have never been able to get a great kick drum sound from a mixer, even a nice mackie w/sweep mid EQ, from my PAS. I can get "ok" but that's it.

As soon as I plug my D6 in with preset 71, it just comes alive...no comparison. I can tweak the sound from there and get it even more tailored to the room, but it certainly needs to start with the preset.

Vocals seem to be somewhat different. I can get closer to preset sound, but still not dead on. I also use vocal mic presets for different than the suggested mic and get good results. I have played gigs with vocal mics EQ'd only from the mixer and get by, but I cannot play a gig with my kick in a mixer. It's just gotta go direct.
quote:
Think if it this way, if you work at Shure, Audix or any company making microphones you have no clue what speaker your customer will use to reproduce sound with your mic. So you voice it for a "best fit" system (or systems) and hope the market (or a part of it) agrees with your deicsion(s).

Now, imagine you knew EXACTLY what speaker your customer was going to use your mic with. Let's say, a Cylindrical Radiator(r) speaker Smile. Well, then you could voice the mic to create a very nice response.

That's what we can do with presets. We can create an EQ curve that attempts to make the mic sound very natural since we know how the speaker and mic will work together. It's that simple.



Well, first of all, I'm a little cynical about microphone manufacturers "voicing" their products. Vibrating membranes have a resonant frequency. Speaker designers try to put it at the bottom of the useful range to get a little added efficiency. Microphone manufacturers try to put it at the top, because the area below resonance is very flat. The problem is that it is real expensive to build a membrane that is tough, generates sufficient voltage, is amenable to acceptable manufacturing processes, and has a resonant frequency that is way up there. What the manufacturers do to keep costs down is accept that they are going to get a bit of the up-slope at the top end of their response curve. Then they call call it a "feature" and a "benefit" for "articulation" even though you would call it junk if it occurred in an amplifier.

Everyone wants to use directional microphones. By the laws of nature, directional microphones exhibit weak low end response when used far away from a sound source, and exaggerated low end response when used up close. So you never know what you are going to get.

Now, a couple of other responses from Folks-at-Bose (which I can't for the life of me find right now) have shed some light on what is going on. First, one person said that the (mic) presets were designed for use "up close". Lips-touching-windscreen close. That is good, because now we know what the proximity effect is going to be doing. So... I assume that the presets "adjust" the proximity effect either completely, or mostly (since many male performers like a little proximity boost). Further, on the other end, I assume that the huge HF hump of a, for instance, OM5 is smoothed somewhat, since we don't have to cut through a monitor mix any more.

Another -at-Bose poster mentioned that a 1/3 octave graph was used for preset creation. This is almost certainly why Drumr likes certain built-in presets to get sounds which he was never able to achieve with channel EQ (See Drumr's post above). 1/3 octave devices have more, finer adjustments available. Pete has admitted to learning (after years of seeking) that "getting back to acoustic, only a bit louder" is the right approach, a view held, I think, by the PAS development team. Presumably, then, both Pete with channel EQ and Bose, with graphs, were aiming at the same sonic point - natural sound. Since Bose had bigger guns, they hit the bulls-eye.

Is *that* what mic presets do? Tame proximity effect? Keep the top end natural? Get pretty close to "flat" at the specified working distance?

Mike
quote:
Originally posted by MTM:
Is *that* what mic presets do? Tame proximity effect? Keep the top end natural? Get pretty close to "flat" at the specified working distance?

Mike


I remember bringing this up nearly a year ago, though from a slightly different angle.

In laymans terms I would now say...... Because the PAS is designed in such a way that highest gain before feedback, thus best PAS performance is easiest achieved when one sings closely to the mic; Bose recommends that approach, and because they offer presets, the presets are set in the manner that best suits the suggested style of mic use.

I don't think proximity effect is lessened anymore with the Bose preset than it would be on any other mic / mixer / amp / speaker combination if it were optimized with a 1/3 octave EQ for close mic technique with one particular make and model of mic.

If one is used to using proximity effect as part of their artistic presentation, it is neccessary to set Gain and EQ while NOT placing lips against the mic so there will be a change as you move closer.

I am more surprised that Bose now says that presets are made up using a 1/3 octave EQ. In the past I thought I remembered reading statements suggesting that the process was much more involved and utilized an EQ that was more sophisticated than could be achieved with 1/3 octave.

Just one mans opinion.

Oldghm
I have a question please. We just purchased one PAS with bass. we are runnign two sm58 wirless to the board and a mini-disc to the board. We have one XLR leaving the board and plugging into channel one on the PAS. We are having feedback problems. What should the preset be set at and where would you suggest
place the PAS? Center stage, or stage left or right?
Thank You,
Frank M
quote:
Originally posted by Oldghm:
I don't think proximity effect is lessened anymore with the Bose preset than it would be on any other mic / mixer / amp / speaker combination if it were optimized with a 1/3 octave EQ for close mic technique with one particular make and model of mic.


Agreed. However, to my knowledge, the only accessible way to do all of the above is with a PAS preset.

quote:

If one is used to using proximity effect as part of their artistic presentation, it is necessary to set Gain and EQ while NOT placing lips against the mic so there will be a change as you move closer.


Agreed. I assume the LF control on the remote is a shelving filter, which will give you the amount of "proximity" boost/cut you want.

quote:

I am more surprised that Bose now says that presets are made up using a 1/3 octave EQ. In the past I thought I remembered reading statements suggesting that the process was much more involved and utilized an EQ that was more sophisticated than could be achieved with 1/3 octave.


Agreed. I happen to own a TEF20 system. One of the things a TEF20 can do is generate a known swept test signal. This signal is sent through a loudspeaker and picked up by a test microphone. At the same time, a filter removes the frequencies just below and just above the swept tone. This effectively removes room reflections. Only the direct sound of the speaker remains.

Need I say that these readings are never anything like what speaker manufacturers publish for their products? Kudos to Bose for not playing the ruler flat speaker frequency response chart game.

So. Time to EQ the system for flat response. I'll just get out my trusty 1/3 octave graphic equalizer, and have at it.

What's going on here? I have a hump in the speaker response, but none of the equalizer knobs are anywhere near the middle frequency of the hump. The closest knob has a curve that is too wide to fix the shape of the hump, anyway.

The above occurs over and over and over again. You quickly learn that 1/3 octave EQs are pretty much useless for anything. The centre frequencies are in the wrong place, and the filters are either too broad or too narrow to fix any real world problems.

Solution: The parametric EQ, which allows you to set the centre frequency exactly, set the width of the filter from extremely narrow to extremely wide, and set the boost or cut at will. There are so many adjustments, however, that to be used effectively, it is pretty much necessary to use a system like TEF20, Smaart, SIM, or the soon to be released MacFOH.

Many of the current parametric EQs operate in the digital domain. It is easy to do, and easy to build a nice user interface (easy for computer hardware and software engineers - not me). They usually show you the curve you are making as you adjust. If you want to play with this, download the ffree (PC) software for the Shure DFR22 from the Shure site.

However, the really cool thing about the digital domain is that once I derive a system frequency response in the TEF (or whatever) I can click on the curve, copy it, click on the parametric window, paste, and the inverse (i.e. correcting) EQ curve will be generated in the DFR22!!

So, finally we get to the point: It seems to me that the right way to create presets, at least as a starting point, is to measure the system frequency response (microphone and speaker), copy the curve, paste into Shure DFR22 or equivalent, copy correcting curve, and paste into Bose preset #nn.

And I just bet that Ken-at-Bose has all the stuff to do that sitting on the shelf in his office. I suspect that because I just happen to know that if you ask them very nicely, Bose will tell you how to duplicate the Bose Panaray Controller curves using several parametric filters. Obviously, they know the frequency response of the speaker, the required compensating curve, and how to take that curve apart and describe it as a series of filters.

Well, that's boring enough for one post. More later.

Mike
quote:
Originally posted by MTM:
quote:
Originally posted by Oldghm:
I don't think proximity effect is lessened anymore with the Bose preset than it would be on any other mic / mixer / amp / speaker combination if it were optimized with a 1/3 octave EQ for close mic technique with one particular make and model of mic.


Agreed. However, to my knowledge, the only accessible way to do all of the above is with a PAS preset.

Mike


I knew when I wrote this I should have said...mic / mixer "channel" /amp / speaker combination.... which could be done at the insert or effects loop, assuming one had an EQ capable of making the "smooth" adjustments.

Mike I haven't checked your public profile, maybe I should, but if you are like me you're not saying much there. You seem to have a wide range of tech knowledge, much greater than mine for sure, would you mind sharing a little of your background?

Oldghm
quote:
Originally posted by Oldghm:
...You seem to have a wide range of tech knowledge, much greater than mine for sure, would you mind sharing a little of your background?


Under duress, I included a little in my profile. Just first date stuff, you understand.

Mike

PS I *think* we are agreeing that however they do the presets, they are actually a very powerful form of sonic treatment that would be difficult to do (i.e. $$$ and complexity) with conventional techniques. Aren't we?

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