Newbie with basic (but confusing) questions

[greatdebate]

I've been doing a ton of reading and searching on these forums, but the more I read, the more confused I get myself. We have a Mackie 24x8 bus mixer and are trying to figure out the proper audio connections to go from various devices to the mixer. Our house system is wired for mono sound.

What I would like help with is figuring out the correct cords to connect the following devices.

*2 Tascam CD01U CD players - we currently have the RCA outs on each CD player going to a single 1/4" TRS cable and then a 1/4" TS adapter that goes on the end of the cable into the mixer. If we don't get the 1/4" TS adapter, we only get half of the signal when we plug it into the line in on the mixer. Also, we only need to have 1 channel on the mixer per CD player..don't need 2 channels per CD player.

*Computer - we have an 1/8" stereo jack going from the headphones out to a 1/4" TRS cable with the same 1/4" TS adapter going into the board. Same problem if we don't use the adapter before patching into the board.

*What is the correct 1/4" cable to go from an Aux Send on the board to a 1/4" audio output on our Listen Technologies transmitter?

*We have a Lexicon MX300 effects unit. Would the correct cables be 1/4" TRS balanced from the Aux Sends into the MX300, and then unbalanced 1/4" cables coming back to the mixer from the MX300?

*dbx 1046 quad compressor - would a 1/4" TRS to (2) 1/4" TS Y-cable be what we need to go from each of our 4 submaster inserts into the in/out of each compressor channel?

Sorry for the basic questions. Not only have I been reading and searching tons of posts on the forums, but I've also read user guides and keep confusing myself more and more.

Links to the correct cables would be greatly appreciated!

 

[TheGuruat12]

Also, we only need to have 1 channel on the mixer per CD player..don't need 2 channels per CD player.

Do you mean you only want to use one fader for the entire device? The way that it is hooked up now will work, but I personally prefer to use two channels, one for the left part of the signal, and one for the right. It's not that big of a deal, but the choice is yours.
What happens is that the signal coming from the device is stereo (it has two individual channels of sound). Thus, you can either combine them into one channel of sound (with an adaptor such as you are already using), or you can give each audio channel it's own input channel on the board.

What is the correct 1/4" cable to go from an Aux Send on the board to a 1/4" audio output on our Listen Technologies transmitter?

What is the model of the transmitter? Do you mean that you need to go to the audio INPUT of the transmitter?

We have a Lexicon MX300 effects unit. Would the correct cables be 1/4" TRS balanced from the Aux Sends into the MX300, and then unbalanced 1/4" cables coming back to the mixer from the MX300?

Yes, but use TRS cables (balanced) for both the send and the return. Or, use XLR3. Either one.

dbx 1046 quad compressor - would a 1/4" TRS to (2) 1/4" TS Y-cable be what we need to go from each of our 4 submaster inserts into the in/out of each compressor channel?

For this, it is pretty much the cable you described, called an insert cable. The tip of the TRS is connected to the tip on one of the TS, the ring on the TRS is connected to the tip on the other TS. The sleeves are all connected together. What happens is the signal is sent out on the tip of the TRS, and the processed signal returns on the ring of the TRS.

Hope this information helps!

 

[greatdebate]

For the MX300, the outputs can be either TRS or TS, and since the Aux Returns are unbalanced on the Mackie, I'm not losing signal by using TS (unbalanced) right?

For the Listen Technologies transmitter yes, I meant going into the Audio Input. It is the ST-800 stationary FM transmitter.

For our computer, an 1/8" TRS to 1/4" TS would suffice for the line in connection as well right? It seems like whenever we try to adjust the volume for the computer through the mixer, the sound does not gradually get louder or softer as it does when adjusting other faders. It seems to change in increments; any reason why?

 

[TheGuruat12]

For the MX300, the outputs can be either TRS or TS, and since the Aux Returns are unbalanced on the Mackie, I'm not losing signal by using TS (unbalanced) right?

Oh, well in that case, just use TS cables for the returns. All balancing really does is help reduce interference in the audio lines. For a short run, using unbalanced should be just fine.

For the Listen Technologies transmitter yes, I meant going into the Audio Input. It is the ST-800 stationary FM transmitter.

I'm sorry, but I can not find an ST-800 on their website. If in doubt, you can use TS. Most devices like those also support TRS, so read the manual, and if it supports TRS, use that.

For our computer, an 1/8" TRS to 1/4" TS would suffice for the line in connection as well right? It seems like whenever we try to adjust the volume for the computer through the mixer, the sound does not gradually get louder or softer as it does when adjusting other faders. It seems to change in increments; any reason why?

Yes, that cable will work just fine. I honestly don't know why the mixer would do that, and only for the computer. Hmmm.... It has me baffled.

 

[museav]

In simple terms, you may have a mono system but the CD, computer and effects unit returns are all stereo sources. You may want them on a single fader but trying to connect stereo sources to a mono input with 'Y' cables and TRS-to-TS adapters is not a good practice for several reasons, both technical and practical. If you really cannot accommodate the stereo sources with separate inputs for each channel then there are some options.

Running the stereo sources into stereo inputs would be the preferred approach. However, the Mackie 24.8 does not really have any stereo inputs, although it does have six stereo aux returns. None of those have any associated EQ or aux assignment capability, but two of the aux returns can be assigned to any of the the eight Group buses (in four pairs) and/or to the main L/R mix bus. The other four aux returns can effectively only be assigned to the L/R mix bus. Depending on your needs and how your system is configured, that might be an option, however since you also mentioned an ALS system fed from an aux send, it may not be practical for your application.

The next best option would be to externally mix each stereo source to mono, then run it into one channel on the mixer. This may require a small mixer for each stereo source, although if you can work with the stereo sources as a submix then you might be able to put the PC and CD into one mixer and the output of that into one channel on the Mackie.

A simpler option would be a basic passive summing/combining network for each source. This would passively combine the outputs of a stereo source to mono while solving some of the technical issues such as providing a proper impedance to the device outputs, however it would not allow addressing differences in source channel levels, split tracks and so on.

 

[museav]

Oh, well in that case, just use TS cables for the returns. All balancing really does is help reduce interference in the audio lines. For a short run, using unbalanced should be just fine.

It depends. The balanced aspect does refer to impedance however many balanced outputs also use signal symmetry with the + conductor carrying the signal and the - conductor carrying an inverted version of that same signal. When run into a differential input the resulting output level is greater than if one had just the + signal. So running unbalanced rather than balanced can indeed relate to a lower signal level. However, you should be able to compensate for that level difference, you'll just need to turn up the aux return level a bit more.

I'm sorry, but I can not find an ST-800 on their website. If in doubt, you can use TS. Most devices like those also support TRS, so read the manual, and if it supports TRS, use that.

Most devices that accept balanced inputs will also accept unbalanced inputs however some balanced outputs may not like having + and - tied together, which is what would happen with TS to TS cables or many TRS to TS cables. Also, some professional devices will have 1/4" unbalanced inputs and use XLR or terminal strip inputs for balanced inputs, you cannot just assume a 1/4" input will accept balanced and unbalanced signals.

I think this is the specific transmitter they have, Stationary FM Transmitter LT-800 - Listen Technologies, and it has a combo XLR/1/4" balanced input. The Mackie 24.8 makes things a bit more complex as Aux Send 1 and 2 are balanced 1/4" TRS outputs while Aux Sends 3, 4, 5 and 6 are unbalanced, 1/4" TS outputs, so the proper cable may depend on which aux send is involved.

Yes, that cable will work just fine. I honestly don't know why the mixer would do that, and only for the computer. Hmmm.... It has me baffled.

An 1/8" TRS to 1/4" TS cable for a computer source is a good way to shorten the life of the computer sound card as you are tying what are actually two likely relatively low impedance outputs (+ left and + right) directly to one another as well as to the usually higher impedance input of the console.

 

[Chris15]

What happens is the signal is sent out on the tip of the TRS, and the processed signal returns on the ring of the TRS.

This is true only on some consoles. On others it is Ring send, Tip return.
You need to consult the user manual or sometimes helpful manufacturers will screenprint the pinout onto the console somewhere near the connectors...

There are proper ways to interface unbalanced to balanced and vice versa and then there is everything else. There's a really nice guide to it out on the web, I just can't remember where. I have an inkling it might be a Rane Note...

 

[derekleffew]

... There are proper ways to interface unbalanced to balanced and vice versa and then there is everything else. There's a really nice guide to it out on the web, I just can't remember where. I have an inkling it might be a Rane Note...

This? Sound System Interconnection

 

[TheGuruat12]

An 1/8" TRS to 1/4" TS cable for a computer source is a good way to shorten the life of the computer sound card as you are tying what are actually two likely relatively low impedance outputs (+ left and + right) directly to one another as well as to the usually higher impedance input of the console.

I never thought of this, that's good to know. I connect mine with two channels, but I never even thought that the adapter method of combining the signals would be harmful. So using an adapter to wire right and left positive together DOES damage the device, if slowly?

 

[TheGuruat12]

This is true only on some consoles. On others it is Ring send, Tip return.
You need to consult the user manual or sometimes helpful manufacturers will screenprint the pinout onto the console somewhere near the connectors...

On this board, the tip is send, the ring is return.

 

[museav]

I never thought of this, that's good to know. I connect mine with two channels, but I never even thought that the adapter method of combining the signals would be harmful. So using an adapter to wire right and left positive together DOES damage the device, if slowly?

Since we're referencing the Rane notes, Why Not Wye?. The potential for damage is dependent on the source output electronics. If the outputs are very low impedance relative to what the circuit is designed to normally drive and if the circuit does not address over-current protection then it can damage the output circuit. That may be a sudden failure or gradual as a result of operating over time at a greater current than intended.