I have a Whirlwind ISOpod that I keep in my iPad case. It takes a stereo unbalanced 1/8" miniplug and turns it to a mono balanced XLR line. It's tiny does the job. I think it ran about 50$. I also have a Radial USBdi http://www.radialeng.com/product/usb-pro that works great. Both or either would suit your needs and be better then the adapter you are currently using. The second HOSA adapter would suffice as well, though is not ideal.
 
You have the same connection point failure potential with any approach. The USB cable with an interface, or the RCA to 1/8th" with a DI type set up. So it's kind of a wash on that front. Thats why I like the ltiblock I linked earlier, the connection is hardwired to the the device, its about $30, tiny and does the job unless you really need stereo sound coming from the laptop.
 
I have a Whirlwind ISOpod that I keep in my iPad case. It takes a stereo unbalanced 1/8" miniplug and turns it to a mono balanced XLR line. It's tiny does the job. I think it ran about 50$. I also have a Radial USBdi http://www.radialeng.com/product/usb-pro that works great. Both or either would suit your needs and be better then the adapter you are currently using. The second HOSA adapter would suffice as well, though is not ideal.

Hi! I am actually not using any adapter. Ha! What’s wrong with the HOSA?
 
Well you are dropping the "shield" (the part that makes it balanced and effective at rejecting noise. If you laptop is near your sound console fine. But it sometimes it will lead people to place the laptop say "on stage" run 50't or longer xlr cables to the console. You then loose the interferance rejecting design of the "balanced XLR" connector. So in some situtation that adapter can be prone to problems in how it is able to be used. The USB Interfaces, DI's and the Isopod mentioned, actually transform through circutry the Stereo unbalacned input into a Mono Summed or Stereo balanced signal for transmission over distances greater then 20ft.

The hosa cable takes the stereo unbalanced input and turns it into 2 mono unbalanced xlr.
 
The one I linked to above is cool b/c it has RCA, 1/4", and XLR outputs. Do you know of a USB audio interface that is similar? And is "USB audio interface" what I search for when looking to purchase / research?

A concern I do have about a USB output is that aren't USB ports more prone to water damage, etc., than headphone jacks? Just concerned b/c I have a used MacBook and worried that I will discover a USB problem mid-show, because...you never know.

The Radial ProAV2? It has XLR outputs. The RCA and 1/4" jacks are INPUTS.

Whatever you were told about USB being more prone to water damage - why is this bit of horse hockey even considered? If you're getting your laptop wet you have bigger issues that the external connections. Red herring.

A USB audio interface can be very, very simple or it can be a multi-input, multi-output device. For playback (output) only, they don't get much simpler (or cheaper) that Peavey's USB-P. It's a "class compliant" USB device which means it is automatically recognized by the computer OS (Win or Mac) as an audio output device. You select it from the list of available device on your computer. What kind of USB problems have you been having? Anyway, if the name Peavey is a problem, Radial Engineering and others make similar devices.
 
I ran sound from MacBook Air’s headphone jack (to XLR into mixer) at a high school theater and it sounded awful.

What do I need between the computer and the mixer? Am I looking for an “external sound card”? “Pre-amp”? “DAC”? And if so, what specs do I need to meet to do well in a medium-sized house?

Also if I am setting up very simple set of 2 speakers for a small (community, low-tech) event, I don’t need a mixer necessarily right?

I'm probably gonna regret this....

So what is "awful" and how does that sound? Seriously. I can say "the wardrobe is ugly" but that doesn't say how or why.

While the 29 cent headphone amplifier chip in your laptop gets deservedly little love for sound quality, it's probably as good or better than the headphone jack in your phone. Wait, I see you have a MacBook... so it's a 39 cent headphone amp chip. Not audiophile quality but usable to drive a console input in many situations.

Now here's what I think after reading about 2 pages of posts - I suspect a couple of things. The first is the way your adapter cable *might* have been wired (and this has to do with balanced and unbalanced signals, and that a tip/ring/sleeve connector can be "stereo" but unbalanced, or "mono" but balanced, and there's no easy way to tell from external observation, and XLR connections are usually balanced audio). The Rane Notes linked to elsewhere, or Wikiipedia, can provide information regarding these (tl, not writing it all). The possible failure of the adapter wiring (if done for "balanced" signals) would result in an audio signal that mostly cancelled out anything panned to the center. EFX like reverb would tend to remain.

The second possibility depends on what "sounded awful" actually sounded like. If you were hearing "digital artifacts" noises of various types, it's the computer. IIRC Apple has had this problem in the past and a couple of Dell models, too. I thought these problems were solved (or the models no longer made) a few years ago but I suppose anything is possible. More recent is laptop power supply noise that gets into the audio output circuitry ("PSU bricks" with 3 prong cords are your clue to listen carefullly) - brand agnostic, but the grounded PSU is the culprit. A passive DI with ground lift is typically sufficient (and often a necessity with some Apple models) when using the headphone output. A "USB interface" does not use the headphone circuit and avoids this problem. See my other reply to this thread for USB info.

As for having a mixer... In some fashion, yes, you need a mixer. It might be a software mixer on your computer or more likely a hardware item. When you say you "ran sound from a MacBook..." were you playing back sound effects, music, or pre-recorded dialog, or where you actively mixing multiple microphones, too?

At the risk of inviting more than you'll want to read in reply... can you paint the Big Picture for us? Tell us about the theatre program, what kind and how many shows they do every year, what sort of venue the shows are preformed in, what audio gear is in inventory, etc... and what are the goals and aspirations of the program and how does the audio dept further those? Is there a budget of any kind?
 
@jsml One caution you need to be aware of: All 3 conductor (Tip, Ring, Sleeve) headphone jacks are unbalanced stereo sources NOT TO BE CONFUSED WITH balanced sources of audio. Too many end users will connect a 3 conductor (Tip, Ring, Sleeve) male plug to an XLR-3 connector then plug the XLR directly into a balanced mono input THEN WONDER WHY THEIR BASS FREQUENCIES and vocals (normally panned down the centre) DISAPPEAR often with the ambient reverberation remaining sounding akin to the cheap 'n cheerful vocal eliminator they've unintentionally created.
I'll butt out now as I'm sure our many experts will be along shortly, if they haven't posted while I've been typing.
Toodleoo!
Ron Hebbard

To clarify...

Balanced connections may have 3 "wires", while not all connections with 3 wires are balanced. XLR connectors are used as "balanced" audio connections, this is what makes their signal cleaner and able to go further. TRS (Tip, Ring, Sleeve) (1/4" or 1/8" Jack connections) can either be balanced or not Depending on how they are used and wired.

For your headphone jack, one wire is left, one is right, and the shield is for "ground" (ie return; like the neutral).
For a balanced jack One wire is "Hot" or "line" (signal), and the other is the "ground" (return), and the shield is the "bond" (chassis ground). This is also how XLRs are wired.

So if you hook up your laptop output to a cable that is a 1/8" TRS jack (headphone connector) on one side and is a single connector on the other side you'll have nothing but problems. (typically) on mixing consoles both the 1/4" TRS and XLR connectors are wired BALANCED, they are NOT stereo.

If you plug it in this way the left and right signals will be "summed" or "merged" improperly, and result in things like Ron mentioned, no low end or messed up vocals. Depending on how it's wired you could alternatively also instead just get the left or right and not get all elements of the track. Also realise that you're now connecting directly to the bond (chassis ground) and going to get issues from that alone.

Also NEVER EVER directly connect an XLR input on a mixer to an 1/8" stereo connector regardless. As mentioned if phantom is accidentally turned on you are likely to completely FRY the circuitry on the connected device (phone, laptop, etc).

DIs - Which come in many different flavours help connect various devices to the balanced low impedance inputs on your console to help get good clean audio.

The Radial Stage Bug SB-5 is a great DI for laptops and phones, connects via XLR to the console.
The Rapco LTIGLBLOX and other models are another great way to connect however are MONO not STEREO on the console side. Great for simple things, also easy to always carry.
The Radial AV2 DI is also amazing, allowing you to connect near anything from a record player to a laptop.

Dante, as mentioned, is a great option on a MAC as you can use "Dante Virtual Soundcard" to connect to a Dante card in your soundboard or such directly never leaving the digital world, no digital to analog conversions! I've had problems in the past with one specific venue, but generally, it tends to work flawlessly. It also allows for a huge number of channels to be connected. Imagine 10 or more individual channels coming out of qlab into your console on ONE network cable!

There are a number of various USB audio interfaces of all shapes and sizes that can also be used. Some better than others.
One advantage of something like this is that if you have a poor sound card in your laptop, or it's not working good, and creating unpleasant sound, you can completely ignore it!
 
Let’s back up a tiny bit. Here’s the physics: your laptop output is running say 0.7-2 volts AC. A mic input on a mixer is looking for a few millivolts. Aside from phase, mono to stereo blending, etc. your fundamental problem is you are overdriving the console input by 3 orders of magnitude. That’s called clipping and means bad, non-linear transfer of input signal to output. On cheap consoles, can also fry the mixer channel. Like powering. 3v LED from 277 volt feed and wondering about that puff-o-smoke.

The LTI block is one good solution. Or if your mixer has input pads, switch in about 50db and see if that’s enough.

The LTI block solves mult issues

Mixes stereo down to mono
Changed unbalanced signal to balanced - what the mixer expects
Provides ground lift in case of nasty 60 hz buzz.

Now back to our regularly scheduled program!
 
I ran sound from MacBook Air’s headphone jack (to XLR into mixer) at a high school theater and it sounded awful.

What do I need between the computer and the mixer? Am I looking for an “external sound card”? “Pre-amp”? “DAC”? And if so, what specs do I need to meet to do well in a medium-sized house?

Also if I am setting up very simple set of 2 speakers for a small (community, low-tech) event, I don’t need a mixer necessarily right?

I have been doing sound in small (zero-budget) theatres for about 15 years now and progressed from using the headphone output of a Windows XP laptop to using an assortment of dedicated Theatre sound programs and hardware. But always on the cheap. In my experience, the best results are to be had with a "USB Sound Card" type of device that has balanced outputs that can be run into the balanced auxillary inputs on a proper mixer. This means that the cheapest USB devices won't work unless you use one of the DI boxes or balancing devices already mentioned. So the next level up is needed. My favorite USB device was the Behringer FCA 610. I say was because it died not long ago. It has multiple balanced outputs and inputs. At the risk of digressing, you will need to decide how many outputs you need. I want more than two because I want sound to come from other places than just the two speakers at SR & SL. Most USB devices have lots of inputs and few outputs because they are designed for recording and not playback. That's where the FCA610 excelled (until it died).
My go-to for stuff like this is Sweetwater (no affiliation, just good experiences). Their USB Audio Interface devices page is here. Look for one in your price range and with the number of outputs you want. If you want inexpensive, there is this one for under $100. I've never used it but I would if I were in the market. Browse what's available and see what fits you needs and then get back to us.
You have not told us what software you are using. Hopefully it's something good like ShowCueSystem (SCS) which I love and is the only reason I keep a Windows laptop around. With that, you can take advantage of multiple audio outputs to put sound through more than two channels.
Why everyone thinks you need a big mixer for a small theater is beyond me unless they are addicted to putting head mics on actors who can't project... What are your needs? Do you need microphone inputs? Maybe one or two so someone can talk from backstage or give a curtain speech or maybe you need to mic a musician? Something like this might do for your first setup. It combines the USB audio device (computer-USB-to-audio) with a microphone input. Need more inputs? Maybe something like this. Don't underspend, but then don't overspend. I spent a long time setting up my first theatre with a little Yamaha mixer that had multiple mixing bus outputs that worked great. I added a separate USB audio device and we were good to go.
Assess your needs. What is the minimum that will suffice for today, what will you need tomorrow.
 
For a cheap USB 2 out I have the Behringer UCA202 with a set of RCA to TS cables.
Normally I use QLab via either Dante virtual soundcard if I am on a Dante enabled console, or either my A&H zedi mixer with build in USB card or my ARX USB-DI, as both have XLR out
 
I ran sound from MacBook Air’s headphone jack (to XLR into mixer) at a high school theater and it sounded awful.

What do I need between the computer and the mixer? Am I looking for an “external sound card”? “Pre-amp”? “DAC”? And if so, what specs do I need to meet to do well in a medium-sized house?

Also if I am setting up very simple set of 2 speakers for a small (community, low-tech) event, I don’t need a mixer necessarily right?

I’m all for a stereo DI input. But I would like to point out that your mixer may already have stereo unbalanced inputs suitable for this use. You likely just need to find the proper adapter cables.
Are there channels that have a “/“ with a single pot to control the two? These are usually the highest numbered channels on the desk. And on a 14 channel desk would be labeled 13/14. They may or may not have an xlr input, most likely to have two 1/4” TS inputs. They may even have rca type inputs.
So explore the input options of your mixer before spending on a DI.
If you can, post the mixers make and model, then we can better guide you.

For your other question regarding a the needs of simple setup the basic needs read something like this.

Source Left>Amplifier >Speaker Left
Source Right>Amplifier >Speaker Right

A line level output from a laptop will likely work with the amps, but a microphone level would not. With Simple passive speakers you will need an Amplifier to drive them, however.
Today’s powered speakers have an onboard Amplifier and usually a simple onboard mixer. So much of your question is dependent upon just what specific equipment you are working with.
 
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While we're all having a bit of fun and exercise, I will point out that @jsml has not logged back into C.B. since Dec 12.
 
One does not need to be logged in to read the thread.
True, but he still hasn't logged back in since they day after he posted.
 
OK so what is the thoughts on the usb output off the Mac when using Qlab. I use this output straight into my mixer (Yamaha MG10XU)( small but does what I need). It seems to work well. Should I run and hide now under a rock?
Regards
Geoff
 
OK so what is the thoughts on the usb output off the Mac when using Qlab. I use this output straight into my mixer (Yamaha MG10XU)( small but does what I need). It seems to work well. Should I run and hide now under a rock?
Regards
Geoff

That's a good way to do it. The USB converter inside the console should be high quality compared that of the computer headphone output. I do the same with my X32, occasionally.
 

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