8•Bus FAQs

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1. What is the purpose of the Flip switch?
2. What is the level setting procedure for the Analog 8 bus?
3. How should I route my effects device?
4. Where should I plug my speakers in?
5. Where should I plug in my headphones?
6. What is triple bussing, and how is this an advantage?
7. Where is the best place to plug in my recording devices?
8. What is the function of the Operating Level switch on the Analog 8 bus?
9. How do the EQ knobs differ and function?
10. Should I record effects while I am tracking, or during mix down?
11. Help, I'm getting noise. What do I do?
12. What is the 5/6 Shift switch in the Aux Send section used for?
13. What is Mix B typically used for? How about the Source switch?

 

1. What is the purpose of the Flip switch?
The 8 bus is an in-line mixer, which means that you are able to monitor playback through the same channels that you are using for tracking. If the flip switch is in the up position, the channel is monitoring the microphone and line input jacks. If the flip switch is in the down position, the channel is monitoring the program material in the like numbered tape return. When you are done tracking on a particular channel, simply engage that channel's Flip switch and you will hear the playback off of the multi-track recorder. This is a benefit because it allows you to hear playback without confusing patch changes. This switch can be used in conjunction with Mix B to monitor as well, making use of Mix B's source switch.

2. What is the level setting procedure for the Analog 8 bus?
First press Solo on the channel you need set levels on. The Solo function on this mixer monitors post-fader. To get an accurate level setting signal set the channel fader to unity when raising the Trim. Keep in mind that a post-fader Solo monitor will also take into account any EQ changes and the Mute switch. When in Solo mode, you are going to see two rows of LED's on the main meter. The post-fader solo is a stereo signal at that point, in contrast to a pre-fader solo, which is monitoring the mono signal at the pre-amp. Keep in mind that both the Mic and the Line inputs go through the Trim; the Tape Return does not.

3. How should I route my effects device?
Let's start by saying that typically you would not want to track effects to your multi-track recorder. Effects are usually added during mix down. This column is written with that in mind. Typically one would use a post-fader Auxiliary Send to feed the input of the effects device and plug the output of the device into a Stereo Auxiliary Return. There are many assignment switches in the 'Stereo Aux Return' area to allow the signal to go to any of the Sub busses, or the left and right Main. To hear the output of the device simply assign it to a bus and select the corresponding bus in your monitor section; you can also hit Solo on the Aux Return if the bus you're using is not available in the Monitor section. Aux Returns 3 and 4 have switches to allow the signal to go directly to headphones, or to the L&R Mains. Aux Returns 5 and 6 sends the signal directly to the L&R Mains.

The other option typically used is to feed the input of the processor with a post-fader Aux Send and plug the output of the processor into an unused channel. VERY IMPORTANT! If you do this, the Aux Send that is feeding the input of the processor must be down on this channel. If you raise the Aux Send on the channel that the output of the processor is connected to, you will get a feedback loop. Very bad!

If you have a stereo processor, it is not necessarily a good idea to split, or Y a mono Aux Send into the left and right input of the processor. This changes the impedance characteristics of the signal flowing out of the jack and could result in bad audio. If you want to use a stereo processor to it's full potential use a pair of Aux Sends, or another stereo bus to feed it's input.

Serial devices like compressors, aural exciters, or an EQ typically would make use of the individual channel Insert jack, or perhaps the Submaster Insert jack. You would want your entire signal to be wet, rather than a wet/dry mix like you would for a parallel device (like a reverb unit). You will need a send/return cable. Plug the single TRS end of the cable into the desired Insert jack. Plug the Tip lead into the input of the processor. Plug the Ring lead into the output of the processor. The effect will now be inserted into the signal path.

4. Where should I plug my speakers in?
For sound reinforcement (PA applications) one would typically feed the speakers with the XLR Main Outs. If you have monitors on stage typically one would use a pre-fader Aux Send to feed these. If you have a separate set of speakers in another room, like a cry room, or perhaps hearing impaired monitors, Mix B would be a good option. You could use any extra Aux Sends to feed those sources if needed as well.

For recording studio applications you can plug your monitor speakers into the Control Room outputs. If you have monitors out in your main tracking room for the performers, plug those speakers into the Studio outs.

5. Where should I plug in my headphones?
You can plug headphones directly into the Phones 1 and 2 jacks. These jacks possess a stereo signal with the left present on the tip lead and the right present on the ring lead. You can split these up with a send/return cable to go to a separate headphone amp if need be. If you have a separate headphone amp, just find a stereo bus that you would like to use. Typically one would use a pair of post fader Aux Sends, but Mix B would be a wise choice for this option as well. If using Aux Sends or Mix B to feed headphones, keep in mind the position of the Flip switch and Mix B's source switch. These switches will dictate the signal that is present in these busses.

6. What is triple bussing, and how is this an advantage?
There are eight Subgroups on the Analog 8 bus. These busses are used to group multiple signals together onto one track. If you are using these Subgroups to route signals to 24 tracks, you can triple bus them. A signal routed to Sub 1 will also be present on Sub 9's output jack, as well as Sub out 17. This will allow you to make an 8 track recording pass, and then another on tracks 9-16 of the recorder without having to re-patch the busses again. Simply take tracks 1-8 out of record ready and put 9-16 in record ready.

7. Where is the best place to plug in my recording devices?
For a multi-track recording there are two place that are ideal for feeding the inputs of the device. The Direct Outs for each channel are post-fader; post EQ, impedance balanced outputs. Feed one of these outs into each track on the recorder and take the outputs of the recorder and put them into the Tape Returns. In this instance the 8 bus is used as an in line console. The Flip switch will allow you to toggle between the input signal that is in the channel and the playback that is in the Tape Return jack. The Submaster Tape Outputs are triple bussed (See question #6). These outputs correspond to each of the 8 Subgroups. It would be to your advantage to use these jacks if you are assigning multiple instruments to one track on the recorder. A group of choir microphones, or drum microphones, can be assigned and isolated to one Subgroup using the assign switches and the pan knob. When using this input method, you can either bring playback into the tape returns, or into the channel through the line input. If you put playback into the line input don't assign this channel to the Sub that is feeding the input, or you will get a feedback loop.

8. What is the function of the Operating Level switch on the Analog 8 bus?
This switch selects whether the nominal output level of the Submaster tape outputs will be +4dBu, or -10dBu. Check the specifications of your recording device to see which line level it's inputs are looking for. +4dBu is usually associated with the input of pro line level devices with balanced inputs. -10dBu is usually associated with the input of consumer line level devices with unbalanced inputs.

9. How do the EQ knobs differ and function?
In the EQ section there are four bands. The High EQ is a shelving EQ with it's frequency fixed at 12kHz. It can provide you with 15 dB of gain or cut at this frequency. This frequency is associated with high sizzle, such as the high overtones of cymbals and vocals. The High Mid EQ is a true parametric EQ. It has three pots associated with it and three parameters to control; + or - 15 dB worth of gain, a selectable frequency between 500Hz and 18kHz, and a bandwidth, or (Q) selector pot which allows the bandwidth to vary between 1/12 of an octave, to 3 octaves. These parameters should provide you with the accuracy you need to boost or cut any range of frequencies around the sweepable mid point. The Low Mid EQ is a semi-parametric EQ. There is a gain pot allowing 15dB of boost or cut, and a frequency selector pot, which allows you to pick a frequency between 45Hz and 3kHz. A bandwidth control is not included on the Low Mid because an octave occupies a smaller frequency range in the lower frequencies. Be aware that there is a split EQ switch in the Mix B section. This allows the Hi and Lo shelving EQ to be applied to Mix B rather than the program material that is in the channel.

10. Should I record effects while I am tracking, or during mix down?
It really depends on the desired result, but we can tell you what is typically done. Parallel effects devices such as reverbs, delays, or other ambient effects are usually not tracked to tape with the initial multi-tracking. Usually an engineer would like to have some time to play with the effects and decide during mix down what the reverb should sound like, once all of the instruments are recorded. You definitely can track your parallel effects by bussing dry signal and the wet signal to a subgroup and using it's sub-master tape out to feed the input of the track. You just need to realize that if you track an effect with the dry signal, the track is done. The effect is set and you can't mix it with the dry signal any further. At times, it is considered a standard procedure to track the signals coming from serial processors such as compressors, gates, or other dynamics processors. These pieces are usually inserted on individual channel insert jacks. The entire signal present in the channel is processed. In these cases you would want the effect that the dynamics processor is generating to be the track on the tape. Compressors and the like are used to get the optimum amount of signal on a track as the performance changes in dynamic level. Some effects devices such as the aural enhancers and unique vocal processors produce a certain timbre that is useful as your final track. In those cases you could hook it up as a serial or parallel device and send it to tape.

11. Help, I'm getting noise. What do I do?
Noise can come from many different sources. We will talk about three different sources: RFI (radio frequency interference), EMI (electro-magnetic interference), and ground loops. RFI can come from either AM, or FM sources. If you have a radio station that is nearby your install, there is a chance that RFI will be picked up by your microphone cables. Making short cable runs, using balanced lines, or using a foil-shielded snake are ways of dealing with this. There is a modification that you can perform on your microphone cables that will squelch out this RFI as well. Contact Tech Support for details on this.

EMI has to do with current induced on line level audio cables from an electro-magnetic field. Any line level cables (especially unbalanced lines) are susceptible to picking up EMI. Keep AC power cables away from your microphone lines, or line level output cables from the mixer. Also, avoid putting line level cables around other sources of EMI, such as computer monitors, motors, fluorescent lights, magnets, and speakers. If you are getting a buzz that seems to be related to the position of the cable in the room, more than likely it is EMI.

Ground loops occur when errant current trying to go to earth ground will go through audio cables to the earth ground of another piece of gear rather than going to it's own earth ground, or chassis ground. If there are outlets in your install that have different ground references this will occur. This will also occur if you have a component that has it's ground in the chassis and it's ground potential is as a higher voltage than the ground potential of the piece of gear it is interacting with. Errant current will always go to the lowest ground potential and if there is a path through another piece of gear to get to this lowest ground potential you will get a ground loop. This is usually heard as 60-cycle hum in the audio. Making sure that your piece of gear has a secure ground is a necessity. As a remedy, try switching around your AC outlets so that all your gear is on the same circuit. Depending on the wiring of your building, you can sometimes have success going the other direction and having the units on different circuits. Check to make sure you're running balanced lines in your setup and see if you can narrow down exactly which piece of gear is causing this hum. Sometimes using a direct box with a ground lift switch can be really useful in device interconnection. The best solution is to use isolation transformers, which are specifically designed to deal with ground loops.

12. What is the 5/6 Shift switch in the Aux Send section used for?
This switch toggles the corresponding channel's Aux Sends between 3 and 4 or 5 and 6. This allows you to operate both Aux Sends 3 and 4, as well as Aux Sends 5 and 6 at the same time. This can save you some repatching if you have multiple effects devices for different channels. For example, you could run a set of reverbs on Auxes 3 and 4 for a group of singers, then use a delay and chorus for a guitar running off Auxes 5 and 6. Just hit the Shift switch on the guitar's channel to move it over to those processors. For these Auxes, only 3 and 4, OR 5 and 6 can be used; they cannot be used at the same time on the same channel.

13. What is Mix B typically used for? How about the Source switch?
13. What is Mix B typically used for? How about the Source switch? Each channel has a dual send called Mix B. Mix B's source can either come from either the mic/line inputs, or from the tape returns; this is controlled via the Source switch under the Mix B level control. There is also a Split EQ switch in this section that allows the high and low EQ to be active on Mix B rather than on the channel strip; the other EQ settings continue to apply to the channel. Since Mix B is a dual signal it has a left and a right bus. There is a pan knob in this section routes the signal across the left and right Mix B busses. Common uses for Mix B include additional monitor mixes, the ability to create a mix from tape while recording, feeds for additional studio headphone mixes, and an additional output source for quick live mixdowns and recordings.

 

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