I cancelled my order for a Focusrite Solo usb interface, primarily because it was mono only & got a Mackie Blackjack instead.
Now I’m trying to figure out what adapters I will need to connect it to my stereo which uses RCA jacks. I’m not real clear on what all of the designations like TRS vs TS connectors & “balanced” vs "unbalanced mean and don’t want to get something that either won’t work, or worse yet will damage some equipment.
I’m guessing that the “Mon” outputs on the Blackjack are mono, since they are marked “L” & “R”… so I would guess that I would get something like a pair of these RCA to 1/4" TS jacks to plug into the Mackie and then connect my current RCA cables from my “tape in” or “aux in” jacks on my stereo. Correct?
I guess that means that I would have to use both “line-in”, XLR jacks to record in stereo from my stereo. That’s too bad. I was hoping to be able to leave them plugged in semi-permanently along with my new mic.
Of course, maybe I could just keep my Behringer UCA-202 plugged in for the stereo connection to my computer and use the new interface for the microphone alone… But will most computers be able to handle two USB audio interfaces plugged in at the same time?
Contrary to Steve I like using adapters as in the end it’s less stuff I end up stocking. But he is right, adapters add another connection which is another point of failure.
The input jacks are clever combo XLR/Phone jacks that have become popular in recent years. Some clever person discovered you could put a 1/4" phone jack in the center of an XLR Female connector. I believe that on the Blackjack the XLR pins are wired directly to the microphone preamp, and the phone section to the higher-level input. (So you do NOT want to use an XLR to RCA adapter to connect your stereo to these inputs).
For both the inputs and outputs the blackjack has balanced (TRS) phone jacks. “Balanced” means that there are two signal wires in addition to the ground, one with the positive signal the other with the negative. Using two wires in this way allows for much longer cables without picking up interference because the interference will (in theory) be coupled equally into the two wires and be cancelled out by the receiving input that works by taking the difference between the two rejecting any “common mode” signal. It can be confusing because TRS jacks are also used in other contexts (eg headphones) to carry a stereo signal.
However for connecting to unbalanced equipment you can just use a TS plug which take just the positive signal to connect to the RCA/phono connectors on your stereo. The equipment makers expect you to do this (I think the Mackie manual explicitly shows this wiring).
And yes you’ll have to unplug it from your stereo to use the microphone inputs.
So I guess it’s one of those cost vs reliability & convenience/flexibility tradeoffs, eh?
The input jacks are clever combo XLR/Phone jacks that have become popular in recent years. Some clever person discovered you could put a 1/4" phone jack in the center of an XLR Female connector. I believe that on the Blackjack the XLR pins are wired directly to the microphone preamp, and the phone section to the higher-level input. (So you do NOT want to use an XLR to RCA adapter to connect your stereo to these inputs).
I haven’t come across one of those XLR adapters yet, but I did see a site that showed how to solder one onto whatever cable you wanted, presumably for this type of purpose, but as you say, Mackie recommends against it:
Can I use the XLR mic inputs for balanced line inputs?
Actually, we recommend that you use the 1/4" (TRS) Line inputs for all your line-level, balanced sources. Just use an XLR to 1/4" (TRS) adapter and you’re done. Although the mic and line inputs pass through the same preamp, the line input has an internal 10dB pad. There is also a “virtual” pad built into the preamp trim control that gives an additional 10dB of attenuation – something you may need for those hot, digital multitrack tape returns.
Yes, that did add some uncertainty & confusion for me.
In unbalanced systems, the T (tip) carries the mono signal in a TS connector, the S (sleeve) carries the ground signal. Depending on the preamp or amplifier you are plugging the TS connector into, the ground signal could be tied directly to earth/cabinet ground, (effectively your ground pin on a 3-prong receptacle). This would be my main concern for reasons explained below.
The TRS 1/4" connector adds the R (ring) to the plug. In a normal stereo application, the ring carries the right stereo channel and the sleeve still carries the ground as described above.
So, optimally, your Pro EQ would use the tip and ring to carry a differential signal (basically both a non-inverted and inverted signal), the tip carries the non-inverted part and the ring would carry the inverted part of the differential signal. Without going into detail, this differential signal would be “balanced” by the fact that neither end of the 2-wire connections would be tied to ANY ground, and in fact, they would be allowed to “float”-typically through an op-amp or optical isolator, etc.
If you use the TS (mono) connector in place of the TRS connector, the (S) sleeve will make contact where the R (ring) would normally make contact to the inverted differential signal and tie it to ground (as mentioned above). In my opinion, this will work. However, you will be shorting the “inverted signal” to whatever ground makes contact with the S (sleeve) of the TS connector when plugged into your preamp or amp, etc.
In effect, you will pull down the inverted part of the differential signal to “whatever” ground you have in the equipment you are using to amplify the signal. This will defeat the purpose of the “floating” differential signal, and you will most likely end up with the “un-balanced” sound you originally asked about.
My last concern would be to make sure the Pro EQ doesn’t have any problem tying the signal ground (e.g. the inverted differential signal) with the sleeve of the phone connector. Most likely you will notice some ground noise.
And yes you’ll have to unplug it from your stereo to use the microphone inputs.
Did you mean I would have to unplug it from the Mackie interface so I could plug the mic’s XLR cable in?
You have no option the RCA cables. They’re unbalanced. The show signal is on the center pin and the protection ground is the circular collar. One cable for Left and one for Right. The main shortcoming with those is short cable runs like from the tuner or CD player to your amplifier.
This shows how you can touch the center pin of an RCA to make noise for testing.
“It can’t be live. I’m touching the center pin and it’s not buzzing or making noises.”
One followup question, if you don’t mind. The interface has balanced interfaces, but the stereo RCA jacks wouldn’t be. If I plugged balanced cables into the interface and then into RCA to TS unbalanced jacks at the stereo would the cable itself still pick up the hum & hiss or whatever as though it were unbalanced?
It wouldn’t make any difference. The key bit is that the inputs on your stereo does not have the ability to subtract the two signals that make up the balanced signal. (or on the output side they are incapable of making the necessary signals).
If you really needed to this (and I don’t believe you have any need) you would need an unbalanced to balance converter of some type at the unbalanced end. The simplest are just a transformer, the fancier models are made by a company called “henry” http://henryeng.com/matchbox.html for about US $200.
The manual for the Blackjack states that the inputs and outputs may be balanced or unbalanced when using 1/4" jack plugs (the XLR inputs are balanced only).
RCA connectors are always unbalanced. Therefore the leads that you need are the one’s that I indicated about 20 posts previously.
As flynwill wrote, “adapters add another connection which is another point of failure”.
They also put substantial additional mechanical strain on the connectors and increase the risk of mechanical damage.
The correct leads are readily available, and if you intend to use this setup regularly there are virtually no advantages in using adaptors to convert the wrong leads, only disadvantages.
The only slight advantage in using adaptors is that you may save yourself a couple of $'s by converting leads that you already own, but it’s a sure bet that if you damage the connectors on either your sound system or your new Blackjack, you will wish that you used the correct leads.
OK, thanks. I guess I was hoping it was some sort of auto-correcting thing, like maybe having that cancelled out by the grounding wire/jacket doing that without any computer power needed. I guess you engineers & sound gurus earn your keep by continually figuring out new ways to reduce noise, improve reliability etc. The added complexity does make it a little trickier for the general public to understand, however. Maybe there’s a market for Audacity For Dummies out there.
If you really needed to this (and I don’t believe you have any need) you would need an unbalanced to balance converter of some type at the unbalanced end. The simplest are just a transformer, the fancier models are made by a company called “henry” > http://henryeng.com/matchbox.html > for about US $200.
Well, you’re right that I don’t have a need, or at least am not in the market, for such a device, but it’s interesting nonetheless.
Thanks. There’s no real danger to any of the equipment if you plug an unbalanced cable into a balanced plug, or a balanced cable into an unbalanced plug/jack, correct? Worst case scenario is just a little additional noise vs using the correct cable/connector combo?
RCA connectors are always unbalanced. Therefore the leads that you need are the one’s that I indicated about 20 posts previously.
Sorry if I gave the impression I was ignoring your earlier recommendation. I was just trying to learn & weigh the advantages & disadvantages of the various options. Trying to save on cables is certainly one factor I was weighing. One issue for me is that I may well be using this for both attaching to my consumer grade, low end stereo & also to the more pro-grade mixers at school & at Church. It may well be that I would need, or it would be preferable to have, 1/4" jacks for the mixers & RCA jacks for the stereo.
Another option I’ll try, though, is to leave both the UCA-202 and the Blackjack attached to USB ports on my laptop most of the time. The UCA-202 could handle the connections to & from my stereo, and the Blackjack for recording with the microphone. I don’t know if they will play well together, however, or if the UCA-202 might add some additional noise to any audio recording via the mic through the Blackjack. I had read somewhere that they recommended disconnecting other USB devices, especially hard drives for that reason.
The classic way to destroy a sound performance is send a USB microphone or sound system through a Hub with other USB stuff like keyboard or mouse. USB is a time shared system. Audio isn’t. There’s no such thing as telling your music to “hang on a second while I go service the keyboard.”
Yes, there are ways to record from two USB sound devices, but typically you don’t get to control each one and the difference between the two internal digital clocks means your two performances will slowly drift out of sync. If you clap your hands at the beginning and again at the end, the clap at the end will be off when you play back the mixed show. My machine asks me which microphone I want the system to sync to, because it can’t use both.
You can get insanely lucky and have two microphones with good timing for long shows, but you can’t tell someone to go out and buy the same microphones to get the same results, because in reality, you supersonically lucked out. This one-off problem is where YouTube demo videos lead people down the garden path. If I FedEx you my two microphones, you can get the same results I did.
Mismatching balanced and unbalanced connections doesn’t produce predictable errors. It rarely produces actual microphone damage, but it can just stop working. Worse, you can have a “magic” mismatch. " I found by accident that it started working with the plug half-way in, so I did the recording that way with my shoe jammed against the plug.
No, I’m not making that up.
You should always be able to point to documents that say you can do what you’re doing. That and know what kinds of equipment you own and what the guaranteed connections are.
Yeah, I can see where that would be a problem. On the other hand, ACX recommends a USB drive for storing recordings. Somewhere else they had recommended a solid state drive to eliminate any sound of the drive whirring &/or cooling fans needed because of it. Yet somewhere else they had recommended not having any usb devices plugged in other than the interface for the mic. That seems a little contradictory unless they’re figuring on doing the actual recording to a computer with only an SSD drive and (& bluetooth or internal keyboard & mouse) then attaching the usb drive later for backup of the sound files, I guess. Or maybe have other I/O options for the microphone sound chain than everything else… maybe firewire, usb, scuzzy drives, blue tooth, ethernet, wireless or whatever.
My laptop does have 3 usb ports, but I guess that’s really the same thing as a 3 port hub, eh?
Yes, there are ways to record from two USB sound devices, but typically you don’t get to control each one and the difference between the two internal digital clocks means your two performances will slowly drift out of sync. If you clap your hands at the beginning and again at the end, the clap at the end will be off when you play back the mixed show. My machine asks me which microphone I want the system to sync to, because it can’t use both.
In my case, I wasn’t thinking of trying to use them both simultaneously. I was thinking of using the Mackie Blackjack for recording from the mic directly to the laptop. I could just use headphones to listen, or maybe use the laptop speakers.
I could continue to use the UCA-202 for recording from the radio or playing audio internet streams through the stereo.
I still have the UCA-202, which uses RCA cables, just like the stereo. No new cables needed and it would eliminate any potential problem related to connecting balanced and unbalanced interfaces together. I would prefer not to have to be plugging and unplugging the two devices in, however. I’ve never read any warnings about that, but assume you add a bit of wear & tear to the USB port every time you plug it in or unplug it. I’d rather not have any of those go bad on me.
You can get insanely lucky and have two microphones with good timing for long shows, but you can’t tell someone to go out and buy the same microphones to get the same results, because in reality, you supersonically lucked out. This one-off problem is where YouTube demo videos lead people down the garden path. If I FedEx you > my two microphones> , you can get the same results I did.
and your left tennis shoe for correct positioning of the TRS jack?
Probably, but not necessarily. You’ll have dig through the documentation for your laptop to determine that for sure. It is not uncommon to have more than one USB bus even on laptops. If it is a windows machine you can use the “device manager” and look for multiple USB controllers which would imply there are multiple busses (see attached – that’s my deskside machine, big motherboard with lots of ports). But it will still probably take careful reading to the manual to see how they are allocated.
Leaving the UCA-202 permanently mated to the stereo would be a sensible approach in that case.
I did plug my UCS-202 into my Raspberry Pi, load Audacity, and was able to record a short test (back to options for totally silent record device). However when I attempted to have audacity play through the Pi’s built in audio jack while recording from the UCA-202 it crashed and burned. So I’d want to do a lot more testing (including making some long recordings) before I trusted the setup for production. The Pi only has a single USB bus, meaning it has to be shared with the mouse & keyboard so that might be the downfall of that scheme.
ACX recommends a USB drive for storing recordings.
ACX still has some scattered postings. They have a hardware recommendation for a Blue Icicle USB MicPre. Now, I’m sure that’s a delightful MicPre, but it doesn’t have a place to plug headphones. Typically, you can’t plug headphones into the headphone connection of your computer without having live echo and delay problems. So this makes their headphone recommendation a little beside the point except to play the work back after you’re done. They may cover this in other portions of the lectures. I’m not done yet.
On my machine, my voice comes back to my ears 1/4 of a beat late, throwing off all the theatrical timing, unless I listen to the mixer or my MicPre, which does have a headphone connection.
