The people who have never designed circuits explain why USB mics suck thread

[moresound]

Bob Bsy?

 

[wheelema]

Look harder! Hint: it's *tiny*

He does this to keep me from finding it.

 

[mshilarious]

First a person who only wants to record a single mic forever is an animal that rarely exists.

Well they do; they are called rappers or fellows who sing over electronica where the vocal may be the only acoustic track. These fellows are traditionally given either rude treatment or bad advice here, and I am *really* tired of it.

The second class is those who will be happy with stereo recording, and that's quite a lot of hobbyists. USB mic design does need to change to accommodate them.

When they start out, they can rarely see that they will want to expand their horizons in the future but most do (or else give up and leave the USB mic to gather dust anyway). I believe the best advice is to suggest the building blocks of a system that can be expanded upon without total replacement in the future.

I counter that it's a mic that will always have a use, especially if they can toss it in their pocket and use it with their tablet.

Second, the "simplicity" of USB mics (I'll call them that since, at the economy end of the market, that's what they're know as) is over-rated and often untrue. Yes, you have one cable to plug in and no knobs to twiddle but just look at how many questions relating to the DAW side of things are caused by the flakey (or at least non specialist) nature of the drivers being use.

With respect to USB AC I don't agree, that is supported natively in nearly all computers and many portable devices. I have seen a much higher rate of driver difficulties over the years with Firewire interfaces, for example. I've never had a problem with a USB AC device; a USB device with its own flaky drivers, sure I believe that, but USB interfaces would potentially have the same difficulties. Again, if the physical circuit components are the same--which they largely are--why would there be a difference?

Third, as hinted at above, for anything beyond the most basic home recording, you need some form of external sound card anyway simply for the output side of things. Yes, there are a few mics that also provide headphone outputs but they're the exception, not the rule--and once people follow advice and buy proper monitor speakers, what then?

You can drive active monitors from a headphone out. Yes, all USB mics should have an out unless they are special-purpose mics where that is not important.

Fourth, the maximum cable length allowed within the USB2 spec is 5 metres. In all but the simplest of set ups, this is going to force compromises in terms of the relative positions of mic and computer. Again, a common theme of advice given on this forum is to be aware of the effect mic placement and room acoustics have on recording.

I almost never use a cable longer than 5m in my studio, and I have a room larger than the average bedroom. I did have the foresight to wire three of my walls with multicore, which nobody is ever going to do in the future; that limits my need for long cables. One solution for extension is a hub, then you get to 10m which is plenty for 90% of home use. The other elephant-in-the-room solution is the inline USB adaptors, that gets around your single-kind-of-mic objection and allows traditional analog extension. Those aren't quite as elegant from a design point of view, but they are more flexible.

Also, when you are recording to a portable device--which will very quickly become the preference--then you don't want the tablet far away from you anyway. They don't have fans, so they don't make noise . . .

The trend is going to be towards going to better rooms/halls/etc. to record with your USB mic and your tablet, and then *maybe* returning to the home studio for postproduction. I mean I always used to stick with the standard advice not to mix on headphones, but a lot of young musicians (and especially their fans) don't even own speakers. Plus, DSP algos are good enough to do a better mix than 90% of hobbyists. Sad but true. Yes, professionals on full-sized mains can do better. Michael Schumacher could also do a better job of driving my car to work, but I ain't gonna get rid of my antilock and traction control because of that, you know? So are monitors even necessary for most hobbyists? It's heresy, but maybe not . . . I still have full-sized soffit-mounted mains in my studio . . . do I use them? Not really. I never even bothered to finish the center and rear surrounds, even though the room is hardwired for them.

The next latest greatest trend will be digital wireless mics to USB dongle. TI has a new chip with CD-audio quality transmission capability for up to four channel audio. Now, of course, there is the AC 1.0 vs 2.0 issue at the moment, and TI's firmware still has some significant limitations, but this is a big step up from traditional FM-quality wireless. TI's solution will probably never be embedded in general use-devices, but I would guess the next generation of digital wireless mics beyond that will have native support on tablet devices. Now not only is the preamp gone, the cable is gone too! And the monitors can thus be wireless too . . . well, they need a power cable . . .

I mean this is going to happen and happen quickly, and if people aren't willing to adapt their advice towards newly preferred methods of recording--methods that get recordists into better acoustic spaces--then they really ought to excuse themselves from the conversation as they will be obstructionist and thus their advice will be viewed as irrelevant.

Not to pick on you, I left it alone on the other thread, but the cheap shot at VSTs? Really, in 2012, you believe that algorithms should not be used to process audio? I mean I can build a compressor or I can write a compression VST. I've done both--well, I designed the hardware compressor but stopped short of a prototype because once I added the BOM I realized no one would buy it. Probably even at half the price . . .

Stuff is changing so quickly, some of the stuff at NAMM blows me away and kicks my ass because I don't get enough time for development. The Line 6 mixer that mixes based on a physical representation of a stage, from a remote tablet . . . man, I had that idea years ago and I spent a bit of time coding a VST mixing environment, but I never finished. There are other VSTs out there like that now, but to combine that with a physical layer wireless device . . . wow. At our local concert series we are already using a StudioLive with remote iPad mixing, not only are shows easier to set up and tear down, but the mix is better and we don't have to give up seats to obstructed view. Great stuff.

I know all you say about the THEORY of digital mics is very true. However, it's rarely accurate in the real world. I stand by my frequent comments that a basic balanced-analogue output microphone and suitable audio interface is by far the best investment to make at an entry level. If I'm guilty of over simplification because I don't put in all the caveats and exceptions, so be it. But at the newbie level such caveats and exceptions add to confusion, not information.

But the thread in question was not a new investment, it was telling a guy who'd already spent $100 to spend $400 more with likely no improvement in quality he would be able to discern in the name of future expandability that he may never want to do. I object to that.

(Oh, and by the way, since I suspect the "people who have never designed circuits" part of the topic title may be aimed at me, I've been involved in the design of circuits for a number of companies. Indeed, if you Google my real name and get past the Canadian footballer and British composer of the same name as me, you'll even find some published scientific papers by major electronics manufacturers that include me on the author list.)

I realize I quoted your statement, but my feelings are principally aimed at Tim O'Brien who has been the anti-USB mic antagonist for years. His comment on that thread was completely obnoxious; yours I merely objected to your physical statement on digital microphones. I'll see if he has any remaining physical-layer objections.

 

[mshilarious]

He does this to keep me from finding it.

You're sitting on it

 

[chrisghost]

I think you are kinda responding to a thread on HR this week, in which a guy wasn't happy with his USB mic, he wanted "a professional sound".

I'm sure you're right if you say USB mics are very handy for people who don't have very high standards (if that's what yóú say rappers are), but remember, the guy wanted "professional" and you're ignoring that context.

A quick search shows Sennheiser, Neumann, Electro Voice don't issue USB mics. AKG and Shure make them, the most expensive one is about $200. That will hardly buy you a good regular mic, not to mention a professional one.

And that is what you're standing up for? A $200 mic which is supposed to have a good capsule, good clock, good converters, preamp cirquit, a healthy profit for both manufacturer and retailer etc. etc., all for $200? Are you sure?

I won't debate that it's possible to build a professional sounding USB mic, it might well be the future of home recording, but wouldn't it be way beyond the home recording budget?

 

[Lt. Bob]

But I'll talk here because everybody is already pissed off at me anyway.

huh?

I'm not pissed at you ...... aren't I part of everybody?
I wasn't aware that anyone was pissed at you ............ fuck ... no one told me!!

Shit ..... what am I .....chop suey? Someone that no one tells who we're all pissed at?!

OK .... now I'm pissed!

 

[Lt. Bob]

Cooooooooooool

For people who want to know - look HERE.

ORRrrrrr you can simply click on the OPs name which gives you the option to visit his home page.

 

[mshilarious]

And that is what you're standing up for? A $200 mic which is supposed to have a good capsule, good clock, good converters, preamp cirquit, a healthy profit for both manufacturer and retailer etc. etc., all for $200? Are you sure?

Yes.

I won't debate that it's possible to build a professional sounding USB mic, it might well be the future of home recording, but wouldn't it be way beyond the home recording budget?

No.

Look, the benefits of much of your list of a professional chain really haven't been well established from scientific point of view. That is not to say there is no difference! I can easily measure some differences that people can't reliably hear, and I can measure some differences that people can reliably hear but they choose the technically inferior solution. And I'm not talking about "mojo", I'm talking about flaws of digital converters. I ran a test here some years ago where people preferred an ADAT-era converter over a then-recent model RME. The ADAT had measurable flaws exactly in the areas that people will say make for bad digital sound . . . and they liked it. That phenomenon is common in preamp tests as well--people either can't reliably tell a difference, or sometimes they pick a sample with excess noise or something, maybe for psychoacoustic reasons, I don't know. Let's not even get into confirmation bias . . .

Mic capsules. Big topic, so just read Harvey's thread. However, I enjoy making a casual study of other peoples' mic "shootouts". Most aren't well conducted enough to draw any reliable conclusion, but those that are tend to demonstrate that preferences are essentially random. I mean people will get a result like 20%-25%-20%-35% and the 35% "smoked" the rest. Uh, dudes, barely 1/3 of the people selected it as their preference . . . Where a better mic will stand out is that it will be slightly preferred on a larger variety of sources than an inferior mic. I think that is the main reason why people say you have to live with a mic to tell if it's good or not--a single mic shootout isn't enough (and multi-source mic shootouts are apparently too hard for people to bother).

Except when it is! Which would be when the recordist only wants to use it on one source--their voice--and it works.

Now if I were Mr. Audio-Technica (all audio companies are named after their founders, of course), I would do an AT2035USB for an extra $50 because I really like the 35 capsule, I think it's great. But is the 20 horrible? Well if it is, then taking out its digital circuit isn't going to make it sound any different or better . . .

 

[chrisghost]

Yes.



No.

Look, the benefits of much of your list of a professional chain really haven't been well established from scientific point of view. That is not to say there is no difference! I can easily measure some differences that people can't reliably hear, and I can measure some differences that people can reliably hear but they choose the technically inferior solution. And I'm not talking about "mojo", I'm talking about flaws of digital converters. I ran a test here some years ago where people preferred an ADAT-era converter over a then-recent model RME. The ADAT had measurable flaws exactly in the areas that people will say make for bad digital sound . . . and they liked it. That phenomenon is common in preamp tests as well--people either can't reliably tell a difference, or sometimes they pick a sample with excess noise or something, maybe for psychoacoustic reasons, I don't know. Let's not even get into confirmation bias . . .

Mic capsules. Big topic, so just read Harvey's thread. However, I enjoy making a casual study of other peoples' mic "shootouts". Most aren't well conducted enough to draw any reliable conclusion, but those that are tend to demonstrate that preferences are essentially random. I mean people will get a result like 20%-25%-20%-35% and the 35% "smoked" the rest. Uh, dudes, barely 1/3 of the people selected it as their preference . . . Where a better mic will stand out is that it will be slightly preferred on a larger variety of sources than an inferior mic. I think that is the main reason why people say you have to live with a mic to tell if it's good or not--a single mic shootout isn't enough (and multi-source mic shootouts are apparently too hard for people to bother).

Except when it is! Which would be when the recordist only wants to use it on one source--their voice--and it works.

Now if I were Mr. Audio-Technica (all audio companies are named after their founders, of course), I would do an AT2035USB for an extra $50 because I really like the 35 capsule, I think it's great. But is the 20 horrible? Well if it is, then taking out its digital circuit isn't going to make it sound any different or better . . .

What random people hear and what trained ears hear are two completely different things. The result of equipment choises and mic placement become apparant when you're stacking tracks.

It's the same with professional cooks, they're mouths are trained to taste more subtle differences, which he uses to compose a dish, in the end result you WILL notice that difference.

Long story short; you're saying that an Audio Technica USB mic can do the same thing as a Neumann U87 and I'm saying that's a ludicrous statement. Not to insult you, I simply disagree.

 

[mshilarious]

What random people hear and what trained ears hear are two completely different things. The result of equipment choises and mic placement become apparant when you're stacking tracks.

That's a nice try, but I am talking about tests done on self-styled professionals. When they inevitably fail, as most do, the usual excuses you have listed are trotted out.

Also, if you need to stack tracks to hear the effects of mic placement, how exactly are you supposed to run a tracking session? Really, you need to hear that effect on one track during tracking, or have an enormously large recording budget that allows for retracking after mixing. That is not professional.

I would say that if you need to stack tracks to hear a difference then you're in the wrong career. If there is a difference, it's there on one track.

Let's say you take 20 tracks of uncorrelated white noise and sum them. What do you get? A louder white noise track, of course.

Now, apply a 1dB boost at some frequency you like--let's pick 3kHz--to 20 tracks of uncorrelated white noise. Sum them. What do you get? A louder track of noise with a 1dB boost at 3kHz.

You'll probably say next that noise isn't music. You are right--noise is far more dynamic and complex than music. So it's much easier to quickly spot differences in frequency response using noise.

On the other hand, it's much harder (largely impossible) to study distortion with noise--but the principle of summation is the same. All "stacking" does is generate more data points than a single source in the same period of time to identify a difference that is otherwise equally present in all tracks. If you test with a sufficiently diverse single track, you'll spot the same difference just as quickly.

Which is exactly what you need to do for mic selection and placement--listen to one source with different mics and or placements and decide which one to use. I mean I guess you could record the same vocal with five or six mics at the same time and decide during mixing which to use, but that isn't standard industry practice.


I will skip your chef's analogy because this is a technical thread about circuit design, and I don't know much about cuisine (I know a bit about wine production, but analogies are tiresome). So I'll leave it at I heart Michel Richard

Long story short; you're saying that an Audio Technica USB mic can do the same thing as a Neumann U87 and I'm saying that's a ludicrous statement. Not to insult you, I simply disagree.

Where did I say that? The U87 is a multipattern mic with a larger diaphragm than the AT2020. I am pretty sure I wouldn't have said that. Now, if I said the AT2050 can do the same thing as the U87, in a general sense I would say that is true. Which mic would I prefer on a given source? I don't know . . . let's do a shootout

 

[mshilarious]

At this point in the thread, Harvey Gerst will enter and post a mind-blowing track and when people ask what mic he used, he'll respond that he heard a loud bang from the interstate and ran out to find a tractor-trailer collision where the trucker's CB radio mic went flying out of the cab and got runover a few times, so he picked it up, cleaned out the gravel, and recorded a whole session with it

 

[WhiteStrat]

OK, I can think of four semi-legitimate complaints against USB mics in general:

- They are mono. OK, they don't have to be--most if not all USB codecs (I assume you know what a codec is) are stereo, so they *can* support stereo operation. That's a design decision, not a design limitation. It's possible for them to be multichannel as well, that's down to driver implementation--see next point.

- They are limited to 16/48. That's only true of USB mics intended for USB Audio Class 1.0 compliance. That is actually a feature rather than a limit, because it means the mic does not have to have custom drivers for it, the AC 1.0 standard is native to *many* devices, especially portable devices.

And is 16 bit really the limit you think it is? Yeah, 16 bit was more work, but somehow we managed to slog through. Read on! First, if a mono mic is what is called for in the application, then the stereo codec can be cleverly used as a differential input--happily, some codec manufacturers seem to use dither that is at least partially common-mode. That means you can realize >100dB mono dynamic range out of a stereo 16 bit converter. Clever.

But even if you're still stereo, is 90dB dynamic range not enough? That was more than anybody had in analog days. Oh wait, you say, we had Dobly back then (Spinal Tap joke, sorry), that expanded dynamic range beyond what the tape was actually capable of. You know what? You can use the same technique in digiland, and there's even an existing AES standard for CD preemphasis--that together with the differential thingy can push A-weighted dynamic range for a mono mic close to 110dB--out of 16 bit! And stereo to 100dB.

But hey! If a manufacturer chooses, they can bypass AC 1.0 and write drivers, and do any sample rate/bit depth they want. How would that be any different from a USB interface? Do you honestly think the electronics in an "interface" are magically different than in a "mic"? Think again.

But wait once more! For a few years now there's been AC 2.0, which is 24/192 and up to six channels (that's off the top of my head, gotta check). It hasn't been widely implemented, but once is it then we'll have 24/192 surround USB mics (ports for extra capsules if you like) with driver-free, universal plug-and-play.

- They are ADC only. Well, not all are, some have headphone ports. As I said, they mostly use codecs, so they are capable of doing ADC and DAC. This is an implementation issue. A corollary to that is you can't select different input and output audio devices with ASIO. That is an ASIO limitation, not a limitation of the laws of physics in the universe.

- The codecs are cheap. Actually they are rather expensive! But that shouldn't matter, because some of them allow SPDIF input. Now it's a funny thing and maybe not implemented often or ever, but you could use the sexiest converter chip you like into a SPDIF transmitter into a USB codec, and the codec will have nothing to do with the quality of conversion. Or you can use a USB transceiver chip with your converter IC via I2S and skip the codec and SPDIF transmitter (several USB mics do that) and write your own drivers. Again, this is implementation, not a physical limit. I find that if you work with the codecs for a while and squeeze what you can out of their circuits, the quality is just fine--as good or better than the prosumer converters before 2001 or so. But I guess nobody ever made a hit record on an ADAT, right?


All of the other objections--and I invite you to try them--are based upon your misunderstanding of digital and analog electronics. So let's hear them.


Bottom line: if a recordist wants a simple, no-fuss, no-muss method of recording *mono or stereo tracks only*, you are doing them a serious disservice by universally panning a class of microphones you largely haven't even tried. You are costing them money, and money=time, which means you are unnecessarily taking away a piece of their life. Please stop it.

Holy fuck! It's about damn time someone said this.

 

[mshilarious]

More random musings:

A few years ago Mike Jasper published his bigass blind (not double blind) SDC shootout on acoustic guitar--84 microphones with a panel of 21 listeners. The mic that most frequently made the top 15 on each listener's list was one of the cheapest in the sample: AT4021.

I wish I had his spreadsheet with position and price for each mic so I could derive the linear regression--my SWAG is that price accounts for about 30% of preference on any given source. That is to say that price matters, but not too much. What I don't know is how much price matters on a whole lot of sources. That would be an interesting and to-date unexplored phenomenon, at least at that sample size.

.

.

.


USB mics have the most innovative industrial design of any class of mic on the market at the moment. Manufacturers are trying all sorts of crazy stuff with USB and also iOS/tablet oriented mics, mainly because that market is mostly free of expectations and is open to technological change. Now, don't get me wrong, some of those designs are . .. less than good . . . but others are interesting and will press the way forward.

Traditional analog mics . . . it's funny, most of the low-end FET LDCs have a form factor as if they have tubes or at least transformers when they actually have lots of empty space inside. Even the mid-tier brands are a bit guilty of that. In contrast, Neumann and Gefell are perfectly happy do to a design that is as small as the capsule and circuit will allow.

Much smaller is possible--I think a circuit could be located right behind the backplate. I think a PCB backplate might even happen someday . . . LDC in a 58 grille with an XLR sticking out right behind it . . . or a USB port, which will probably happen first . . .

 

[JimmyS1969]

I will just put forth a little point; I myself would not suggest anyone invest in a mic (USB) that limits them in the future. An interface that allows use of multiple mics, sounds like a better investment to me. Nothing against starting out with a USB mic by any means, but is it really the best choice? For who? I'm not sure that is possible for anyone to judge. Those who limit their options from the start, will end up spending more later, if they get to a point where they want to go further.

Was my Bigwheel a waste of money? No, I had great fun with it. Then I upgraded to a Green Machine. Is it useable for transportation now? Not really, now that I have a drivers license and a motorized vehicle. I damn well wont take my Bigwheel to work. Though, that would be kinda awesome.

Regarding advice to members, if my 1 year old boy asked if I would recommend dropping out of high school, and getting a GED instead, what do you think I would recommend? What had the most use in the future? Starting with a viable investment in the future, makes more sense than taking the easy (inexpensive) route to me.

This does not mean that a USB mic can not be the perfect choice for some. It really just depends on the needs of the user. Informing a member that using it has limitations, and recommending a better investment, seems sound advice. $100 interface, and a mic comparable to the USB model, as well as ability to change to 'any' other mic, without loosing use of the first purchase, seems to make 'much' more sense. Most of us know that one mic is not the best for everyone, or everything. 'Advising' anyone to go with a limited option purchase, is just unfair. That is what the manufacturers marketing is for; selling..

My morals tell me to avoid recommending a poor purchase. Though my opinion of poor, has been tainted with quality, I suppose....

 

[mshilarious]

This does not mean that a USB mic can not be the perfect choice for some. It really just depends on the needs of the user. Informing a member that using it has limitations . . . seems sound advice.

I agree with that.

I don't agree with this:

Write this down:

"USB mics are for podcasters."

Get an interface and some real mics.....

$100 interface, and a mic comparable to the USB model, as well as ability to change to 'any' other mic, without loosing use of the first purchase, seems to make much' more sense. Most of us know that one mic is not the best for everyone, or everything. 'Advising' anyone to go with a limited option purchase, is just unfair. That is what the manufacturers marketing is for; selling..

USB interfaces are limited too. Most of them are stereo with P48 on their XLR inputs, because the market demands that or it isn't "full featured". That forces them to be USB high-power devices (500mA). Some are self-powered via wall wart, but the recordist might want to be fully portable. Some tablet USB ports will allow only USB low-power devices (100mA), which nearly all USB mics are. Plus, there may be no drivers for the tablet even if a powered hub is inserted.

So if the recordist wants to use a tablet, a traditional USB interface could be as useless to them as a USB mic is to you.

 

[JimmyS1969]

Agreed there. This is why 'users needs' are a definitive point to the whole conversation. Don't tell someone you need ProTools to make a mixtape for your ex girlfriend. At the same time, don't recommend that a plug and play mic, connected through a built in soundcard, via USB, 'will' give 'professional' results either. It might be possible somehow, with experience, but probably not, due to limitations of stock hardware. I think the point is how manufacturers claim more possibilities than the ability of a user is capable of, thus creating a false sense of what can be achieved with basic crap AD conversion with a stock soundcard.

I feel a personal responsibility to inform people who are new to this whole recording thing, of every option. Taking out the option of starting out small, and moving up later, is not cool. But at the same time, money can be saved by not jumping in with propaganda given by manufacturers claiming "PRO QUALITY", from devices that are obviously limited.

By the way, I would love it if someone would make a Big Wheel/Green Machine for adults!! Start a gang of delinquent 40+year old's, willing to get some road rash!

 

[mshilarious]

I wish the whole "pro" thing would just die (no, this isn't an anti-Behringer post, per se ). Back in 4-track days nobody cared about pro. Then a few people could afford ADAT, then PCs, then suddenly it's 100 tracks on every tunes and 13 plugs on every track. But the music isn't any better, just a bit more produced.

Hopefully kids will take a new generation of portable tools and make some fun music again, free of all this crap (software, hardware, and mental) we've loaded ourselves down with.

 

[Bobbsy]

After a night's sleep, maybe mshilarious is right for some users in the future of recording.

I'm old enough to recall a discussion with my father in the mid 1960s. For hobby reasons, he owned a big old reel to reel tape recorder--two track (one each way) i.e., not even stereo. (For those of you in North America, it was "Silvertone" brand purchased from "Simpson Sears" mailorder.) In some kind of raffle, he won an early compact cassette portable recorder which he passed on to me dismissively saying "it'll never be good enough for music with a speed of only 1 7/8th ips".

Maybe I'm being guilty of the same thing. There's absolutely no reason that mics can't be produced with a built in A to D and a USB output--and this might suit some people whose needs are limited and unlikely to grow.

Having said all that, I'm still not convinced by the present generation of USB mics. I still see all the complaints about driver/interface issue (which is see as more common than mshilarious) and also issues with using a headphone out for monitoring purposes. I also suspect that the number of people who will be happy forever with a single mic on a maximum five metre cable is going to be a relatively small subset of those enthusiastic enough to join and post on a specialist forum like this.

In view of all this, I think I might modify my stock response to people thinking of buying a USB mic from "don't buy one" to "think long and hard about the future--here are my reasons". That might change when a next generation of technology comes on stream (especially if somebody produces a mic with an ASIO driver and proper monitor outs) but for now that's as far as I can go!

Thought provoking discussion though!

 

[zorf]

I love my apogee ONE which basicly what you are talking about, but slightly larger.
i also love my ipad.
Just need a really nice mic solution for the pad.
love the one cable thing.
Apparently, a lot of other people have the same idea, as there is a ton of ios audio stuff coming out lately.
I'm ready for my wireless/tube/ usb/ bluetooth mic and companion wireless headset combo now.
Agree; headphone mixing is fine for a lot of us.
Cool thread.

 

[PRHunt]

Hopefully kids will take a new generation of portable tools and make some fun music again, free of all this crap (software, hardware, and mental) we've loaded ourselves down with.

A new generation of portable tools that excludes Autotune.

If you can't sing in tune, then don't sing. Just. Don't.

Paul