There are several factors that have to be considered/weighed when determining subwoofer placement Physical size is one of the obvious ones. Clearly the size and weight of the subwoofer is a consideration that will probably out weigh the sonic considerations. There are advantages and disadvantages to each one of the following situations. There is not a “best”, but rather a best for a particular situation-or best compromise. So the pros and cons of each will be discussed.

The four main variables are Ground or flown? Center cluster or split left/right. And of course variables/combinations of each. FLOWN OR GROUND PLACEMENT? Ground placement will usually result in more impact to the sound. This comes from a couple of factors.

Being physically closer to the subs can result in greater output for some listeners, and the coupling with the floor can give some tactile vibrations that can be felt. Flown subwoofers actually use the inverse square law to their advantage. Since the difference in level drop is the same from 1’ to 2’ as it is from 20’ to 40’, the level difference will be much more even. We encourage you to download DDT 2D and experiment to find the best solution for you. CENTER VS SPLIT clusters A center cluster will generally provide the most even response (without peaks and dips).

However it does so at the expense of being really loud in one area and quieter in all others. Split clusters (a sub on each side of the stage) will have some problems. Among those are a “power alley”, a louder area often right down the middle of the room. There will also be various peaks and dips in level throughout the room that will vary from place to place depending on the freq and the spacing of the subs. Again, you can use DDT to model all these configurations an evaluate what works best for you.

There are basically 2 different directional sub configurations: the cardioid array and the end-fire array. DDT 2 D is a great way to model both of these configurations.

There is a tutorial on cardioid sub arrays in the DDT 2 D manual. In BOTH cases, The price you pay for the directionality is more subs! With a cardioid array, some of the subs are facing forward, i.e. towards the audience, and some are facing towards the rear, or away from the audience.

The rear facing subs are used to provide cancelation thereby creating the familiar cardioid coverage pattern. The advantage to a cardioid array is more rear rejection. The major disadvantage is that the rear firing boxes do not contribute at all to the sound covering the audience. The end-fire system points all the subs towards the audience, but places them in a line, one behind the other like train cars. Spacing of the boxes is critical as it the application of delay to the boxes.

The advantage to an end-fire system is higher efficiency as al the boxes contribute to the audience sound. The disadvantages are that the array will likely require lots of room, and the spacing of the boxes is critical.

On most of the Danley products (the exceptions being the dual impedance models which will be discussed later), the NL4 jacks are wired to Pin 1 + and -. Pin 2 is passed through. A positive voltage connected to pin 1 + will cause the cone to move out of the basket. The two jacks are in parallel. So it does not matter which jack you use. Either jack is an input or a “pass through” or a jumper connection to another cabinet. DO NOT hook 2 channels of an amplifier (1 to each connector) to a single cabinet or damage to the amplifier will result.

DUAL IMPEDANCE SUBS On these cabinets the wiring is a little bit different. There is a locking switch that has to be pulled out and then moved to the other position and then let loose to lock into position. This is offered as a flexible option to those who want to power the subs in different way. In the 1×4 ohm position-the cabinet is wired up as single 4 ohm load to pin 1. Again, the connectors are in parallel. This will present a single 4 ohm load to the amplifier. However in the 2×8 ohm position, 1 set of drivers (or a single driver in most other cases) is hooked up to pin 1-again in parallel. Pin 2 is passed through to the other connector in either position. This will present 2- 8 ohm loads to the amplifier-so 2 channels can be used to drive the cabinet (or 2 amplifiers in bridge mono mode each) The second set of drivers (or other driver in most other cases) is hooked up to pin 2. In this case pin 2 is passed through to the other connector-making it in parallel. In the 2×8 ohm position, the loudspeakers (or sets of loudspeakers in the TH812) have no electrical connection to each other-so any number of different amp combinations could be used to drive the 2 independent loads. So it could be wired up with a single NL4 cable (1 amplifier on each set of terminals) or with 2 cables-one wired up to the pin 1 terminals and the other wired up to the pin 2 terminals-and plugged into the separate jacks.

In the Single channel operation, if you plug a signal into the pin 2 jack-nothing will happen (sound or electrically wise) as it is not connected to anything (except the other jack).

First you will need to get access to the rear of the high freq driver.

Different Danley products come apart different ways-so contact Danley for the particulars for the individual cabinets.

Unplug the wires going to the terminals on the diaphragm. This is usually a white and black pair of wires. The white wire (or lighter colored wire if not white) will go to the + or RED terminal.

There are usually 4 to 6 screws holding the diaphragm in place. Remove them and then carefully pull the diaphragm straight backwards. Please contact Danley Sound Labs to see if they want you to send the diaphragm or photos to them for evaluation of the failure. It is very important to make sure the gap where the voice coil goes is free of trash that may have been left over from the previous failure. The gap is the slot that is round. You should visually look into the gap with a flashlight to see if you see any small (they may be very small) pieces of anything, so you can check to see if you have removed them. You cannot see the complete open area-just the slot at the rear of the magnet.

Some debris can “hide” just under the rear plate. The two basic methods of debris removal both use masking tape.

One method is to fold a piece of tape at a 90° angle (with the sticky sides out), then fold one leg back over the other piece. This will form a triangle that is sticky on both sides. Stick the “pointy side” down as far in the gap as you can, and run it around the gap. Do this several times, each with a new piece of tape.

Another way is to use a business card with tape folded backwards over an edge-so the sticky side is out. Now push the card with the tape into the gap and run it around the gap. The card just gives you more “pushing power” to get the tape in further. Be sure to inspect the tape for any debris. Keep cleaning until it is all clean. Then visually inspect the gap to see if any small specs remain.

Sometimes a large “chunk” will be stuck to the side with the magnet pull greater than the stickiness of the tape. In that case insert a piece of tape into the gap (with the sticky side towards the debris) and then double over a business card and push it between the non sticky side of the tape and the magnet wall opposite of the debris. Then try to push the tape on to the debris to get better adhesion.

Sometimes you have to “fish out” some pieces. When the gap is clean, carefully push the new diaphragm into place.

NOTE: If there are any plastic spacers between the diaphragm and the magnet-BE SURE to REUSE them. They are specific to the magnet assembly-not to the diaphragm. Then screw down the mounting screws. They need to be good and snug, but not tight enough so as to deform the diaphragm. Hook up the wires to the terminals they were removed from and reassemble the cabinet.

While this may seem like a simple question, the real answer is quite complicated-with lots of variables and “it depends”.

For example. Are you asking how loud it will get-or loud will it measure on a SPL meter? These can be VERY VERY different. It depends on the response time of the meter-the weighting of the meter and so forth. At one very loud rock show we did we took some measurements. These are all with the same meter-at the same location-same band-same song. At FOH A weighted slow we were around 106-107dB. C weighted slow was around 118dB C weighted fast was around 128dB Peak/impulse was around 136dB That is a difference of 30, which is a ratio of 1000. Or to put it another way-the same difference as between a 1 watt amp and a 1000 watt amp. So you can see with the same loudspeaker-very different readings can be measured. We also have to assume your meter is properly calibrated for accuracy.

Cheap meters have been known to vary quite a bit. So while the loudspeaker system was producing 136dB-if you had a meter on A slow-you would only be reading around 106-107dB. And you might think that the loudspeaker system was not getting anywhere near as loud the specs show.

You also have to remember that music has a dynamic range-and the peaks are much higher (and shorter duration-hence the response time of the meter) than the average of the music. This has to be taken into account when figuring out which loudspeaker and amplifier size is needed for a particular job/loudness. So while the numbers published are what the loudspeaker can actually produce-what you read on your meter may be quite a bit lower-or not-depending on the settings and the quality of the meter.

DISTANCE When you move away from any loudspeaker (on axis) the sound pressure level will drop. How much depends on a number of factors. The following is assuming outdoors without reflections. Indoors-the room itself can have lots of influence on how much the sound drops off with distance. The reverb time of the room can also help to smooth out differences in level indoors-so the numbers ay not seem to “act right” in certain rooms. Outdoors the readings will be more consistent. Point Sources A point source loudspeaker will generally drop off at a rate of 6dB every time you double the distance. The difference between 1’ and 2’ is 6dB. The difference between 200’ and 400’ is 6dB. So you can see that the biggest differences are lost up close to the loudspeaker.

The formula is dB loss=20logxd1/d2. Lets’ say the SPL spec is 1m (standard) and you are at 30M distance from the loudspeaker. So 30/1=30. Take the log of 30 and you have 1.477. Multiply that by 20 and you have 29.5dB. So 30M away the SPL would be expected to drop 29.5dB. Or close enough to easily remember as 30M=30dB.

Another distance to easily remember is 10M=20dB. So if the max SPL is 130dB, then at 30M it will be around 100dB-accounting for the 30dB loss. This is also assuming ON AXIS measurements. If the point source is flown (typical) then the level at the rear of the listening area will remain pretty much unchanged-but the level up close will not be as loud as the 1M measurement would suggest. This is because the closest listener is not actually 1M away and they are in a lower level part of the coverage pattern-so very often the level is the same (or very close if well designed) for the closest listener and for the furthest listener (of interest). Line Arrays.

It is often stated that line arrays only drop off at a rate of 3dB whenever you double the distance from them. This is only partially true. It is true as long as the line is long enough in relation to the particular freq that this will happen. For the high freq this does happen (with lots of interference along the way). But with low freq-unless the line is very large-it will drop off at a rate of 6dB-just like a point source.

So with those types of devices, you have to be specific about the freq of interest when stating loss over distance.