Jump to content

Red Spade Audio

Members
  • Content Count

    270
  • Joined

Community Reputation

209 Excellent

1 Follower

About Red Spade Audio

  • Rank
    250+ Post Club

Profile Fields

  • Location
    Melbourne
  • Country
    Australia
  • First Name
    Paul

Recent Profile Visitors

The recent visitors block is disabled and is not being shown to other users.

  1. When choosing sub positions, by far the most important performance issue is the room transfer function. In other words, the frequency response you get from particular positions - both the sub/s and your listening position. It's not very common that you will end up with subs in those positions you mention after a proper assessment. Those positions usually reflect not having gone through a well considered assessment. There are some rooms in which a good position for the mains is also good for the subs. Not very common but even in these cases, generally it's not so much that these positions are better, rather they are "good enough" to work with. In those situations, do you actually need a sub? You might but it's then about some of the lesser advantages of adding a sub. Things like adding a fuller bass or getting more extension. For most people, the bigger advantages are that other positions work much better to give you a smoother frequency response. Most of the time, putting subs near the mains will negate the biggest advantages of having subs!
  2. This driver arrangement won't make any real difference regarding room interaction. It replaces a single driver with a compound driver arrangement energising the room from 3 positions. In some cases, you can get a slightly better in-room response, based on effectively having 3 subs close together. The offsets can smooth each other out very slightly. The improvement is marginal. In many cases, adding subs that are metres apart doesn't offer any real advantage. This kind of driver configuration does have real advantages, including: opposing forces resulting in a more inert cabinet avoiding a sub that "walks" (not a common problem) multiple smaller drivers will often give you more thermal power handling and reduced thermal compression you can get away with less excursion, which is helpful if you want to create that modern look without big visible rubber surrounds So why doesn't everyone make subs like this? Short answer: it's a very expensive way to make a sub. In a 3.5 x 3.5m room you can be fairly confident you will get a big nasty mode around 50Hz. This will tend to stick out like a sore thumb, very often masking lower bass that you might actually have but not appreciate. Sometimes you can get in-room extension well below the tuning of your speakers but have a room mode that takes your attention away. A lot of assumptions get made about getting bass right in rooms and very often they prove to be wrong. Subs don't always provide the expected advantage. 2 is not always the right number. Where and how you should bring in a sub is often not known before you investigate the room. But one assumption that is fairly safe is that you will most likely need some EQ. Coming back to your question ... all of those subs will work well if you get the integration right. Choosing the sub is the fun part and easy part!
  3. It depends on what you are actually measuring. For personal use in your listening room, you probably don't need to look any further than the usual suspects. In many cases, it might not even be critical to have it calibrated at all. Firstly, keep in mind that with in-room testing, you will get big variations simply based on position. If you want to see how your room measures acoustically, an uncalibrated Behringer ECM is perfectly fine. Even one that varies considerably from average. For integrating subwoofers, including EQ, the situation is similar. Of course, many aren't happy with the uncertainty, especially regarding very low bass. If you want to be more confident, it's not much more to get a mic from Cross Spectrum. The exchange rate is a bit nasty right now, so it's not the best time. For in-room measurements, USB mics are very tempting due to their simplicity. Convenient, cheap, easy. For designing and testing loudspeakers outdoors, you might start to get more particular. Here you want to be more confident. Here I prefer XLR mics with a long cable. Computer indoors, speakers elevated outdoors. Try doing this with a USB cable and a laptop outdoors on a sunny day. With speaker testing, it's not just about calibration but also factors including noise floor, distortion and SPL. Pro mics are optimised with different parameters in mind, that's why there are so many of them. If DEQX becomes an integral part of your system, it's worth considering an Earthworks mic. On the other hand, for most personal use in a listening room, there isn't a real need to go beyond a basic entry level measurement mic.
  4. There is no direct connection between size and sound quality. It's not the case that bigger is better. The mouth size determines how low in frequency you can maintain a given dispersion angle. In a two way where a tweeter horn mates with a direct radiator, a good rule of thumb is the waveguide or horn should be close to the width of the mid. It's not quite that simple but close enough for our purposes here. Typically in an econowave type design, the waveguide or horn will match the dispersion of the mid at the intended crossover point. So a 12" midwoofer goes with a 12" waveguide that only has to maintain dispersion down to about 1.2k. The PSE horn is larger because we're horn loading the midrange, with the goal of keeping a consistent beamwidth down to around 350 Hz. The result is that it behaves differently in a room. You maintain a narrower beamwidth in the midrange. Normally the only way you hear that in a room is with dipoles but they have a figure 8 pattern. When you do this with a horn, you don't have all the rear energy. Hence the sound is very different. A dipole has a deeper soundstage due to the energy going back to the front wall but the image is not as sharp.
  5. Movies are mixed for considerable dynamic range. This means when dialogue is at a comfortable level, you can run into more dynamic parts that are louder than you can get away with. The simplest solution is a "night mode" which reduces the dynamic range, which means the louder parts aren't as loud compared to quieter parts (including dialogue). Sometimes the best solution to a bass problem is the exact opposite of what you might expect. Too much bass? Get a sub! Here is an example: This is the bass response of the mains in an apartment with concrete floor, ceiling and walls - it's a cave! The bass booms around 35 Hz which would disturb the neighbours but the midbass is actually missing, around 40 - 60 Hz. So in this example, the neighbours are disturbed but in the room you are still missing out on a lot of bass. In the same room, here are some sub positions that work much better. Just two small subs would work well. The blue position has much better upper bass, the red position has more midbass. There were no perfect positions that completely avoid mid bass dips, it's quite a difficult room. Now let's see how they compare: We used a little EQ on the subs in this example but you can see that no amount of EQ is going to get the mains to equal the smoothness of the subs. On top of this, you might filter out more of the low bass. The result is better bass and less disturbing neighbours. You could probably turn up movies a little more before disturbing anyone. Keeping in mind, this might not be the situation experienced in this case at all. It's just one example of how subs can be used as part of the strategy for getting the best bass in your room. Measurements are required to work out the best positions and if subs provide you with an advantage in your room. It's not universally true that subs will always give an advantage. There are rooms in which the mains are in ideal positions for bass, with little to no improvement in room response with subs. In most cases, however, we can find sub positions that work better. An inexpensive unit like MiniDSP 2x4 is great for applying EQ and filtering. Typically it will give you the power to do things an AVR won't allow but it does require setup from someone who knows how to measure and manually apply EQ and filters.
  6. Not many speakers allow for this. Most serious equipment has moved away from tone controls. Even if they are suitably transparent, quite often they just don't do what is needed. Bass tone controls often have too much low midrange energy and I always found they took away headroom to quickly. Eventually I found a better result in creating a more satisfying bass balance with a sub with DSP. Far greater control. The surprise for many is that doing this improves everything - not just the bass. Sometimes a system can sound too forward or bright because there is not enough good bass which provides balance. Likewise, treble controls are often not quite right either. I'd argue that it's less about tone controls being suitably transparent and more about the fact that better equipment has moved away from including them.
  7. Horns are a very big group and many of them are turd. It's a very diverse group. When horns fail, they can do it on a grand scale. So you can't really say they are all good for one particular reason. They aren't all good and there are multiple things they get right when they do work well. You can design cone and dome box speakers with good directivity. Harman focus on this based on their research which showed a preference for smooth transitions and well behaved off axis response. Some people might prefer horns that actually have an inferior design in terms of directivity - it could be about dynamics and a particular tonal balance. Audiophiles are a funny group sometimes! You can also design speakers that are very good with directivity but limited in dynamic range. Some people find that underwhelming after getting a taste of horn dynamics. In my experience, when someone likes a speaker, it's never really just one thing.
  8. Sometimes what grabs your attention in a shorter demo gets annoying when you live with it. This can be compounded by the way we can tend to zero in on flaws - now we can't stop hearing them! Sometimes the answer is as simple as a different tonal balance. How your speakers are voiced can be a big part of what you seem to be experiencing. For decades the trend has been to eliminate any chance the listener has to alter this in any way! This could be a matter of preference rather than good/not good.
  9. More than likely quite a few things are going on at the same time. Let's say we are comparing to a conventional cone and dome speaker. If the direct sound matches in response, the reverberant field is different. If the response is matched in the listening position, this requires EQ which will reduce the difference in tonal balance, so we are altering the direct sound. Either way we have a different balance. Cone and dome speakers generally need to have a flatter on axis response. If you reduce the treble they are more likely to sound dull when you put the speaker in a room, with more high frequency absorption and a falling response off axis. When you put a compression driver into a waveguide or horn, I find that you generally need to attenuate the treble in the axial response but this varies with different combinations. This involves a room interaction that can have a huge impact. Further, every speaker has a sweet spot - an SPL level you can listen without fatigue. Often much lower than the max SPL on paper. A horn might be loafing along where another speaker is showing signs of stress.
  10. The absorption isn't normally considered because the transmission is so high. Glass has approximately four times the density of bricks but as it's always thin the mass is still quite low. All practical windows perform very poorly in terms of keeping bass in the room - even acoustic windows with a high STC rating. Rooms with lots of openings and many large windows and light construction can actually perform quite well in the bass due to being lossy. Some of us are music lovers who don't care for the technical. Some of us are gear junkies who love our shiny hifi toys. Some of us are tech nerds who enjoy learning about the science. I'd say most of us are some kind of mix. Music is often the excuse that justifies our love of tech and toys but in reality I'd argue that any mix of the above is a perfectly valid interest for anyone to take on.
  11. The article is written for studio owners. It makes sense in that context where it's about mixing decisions and getting SBIR to behave is more important. In that context, the speakers might either be soffit mounted or on a mixing desk not far from the front wall - a nearfield monitoring situation where you don't get the kind of sound stage we all want at home. At home, the offset from the wall behind the speakers has more impact on the sound stage. For many, getting this aspect right trumps SBIR.
  12. In that room it would be worth considering an AT screen with black acoustic panels across the entire front wall - hiding everything so that your wife no longer cares what is behind. You could hide it all behind there - speakers at the right height, all equipment, as many subs as you want and a bass trap across the entire front wall. A room of those dimensions will have heavy duty room mode peaks in the midbass. Just one Ultimax 15" in a sealed box with 500W would most likely give you loads of punch due to the midbass room modes. Ultimax drivers don't tend to work well in horn sub designs. Horn sub designs are usually not limited to just one driver and in some cases, you can also use a different size. But it's never a random swap - there are many cases where a design will work very poorly with a different driver. When you put a horn sub in an Australian room, the bass extension will typically be close to how it measures outdoors. Hence, if you want to get down to 20 Hz, the sub needs to be tuned that low. If you put a 30 Hz horn sub into a small room like this, you will likely get loads of midbass, which you would need to EQ out. At 20 Hz it may not be so impressive. Keep in mind that horn subs tend to have upper bass resonances which limit their bandwidth. If you run it with audible resonances, the bass won't sound articulate and refined - it might even sound like a $500 sub. Consider also the middle position across the front wall. Sometimes it can work well but that depends on both your room and seating layout. With a pair of horn subs behind a screen you can hit both corners, the centre or the centre and a corner. It's always best to test! If you are buying Dayton drivers, buying local from LSK will save you shipping them back to the US in the event of warranty claims. When it comes to choosing a design for a horn sub, there are two things you want to avoid. One is a design that lacks the extension you are targeting. The other is audible resonances within the passband of the sub. Both are difficult to avoid. A few of the BFM subs were tested here: http://prosoundshootout.com/ It's a bit of a maze of forum posts to get to the results, but they are in there.
  13. You can export sims from Hornresp into REW so you then see your model against the measurements. Hornresp models often look worse due to the scale, with 5 dB divisions over a smaller range on the y scale.
  14. Intuition tells us that if a thick absorber is better and density helps, then we want more of both. But it's slightly more complex. For any given absorber, there is a point where it becomes thicker than optimal and this effect varies with frequency. You can end up with an absorber that might perform poorly in either bass, low midrange or even both, in comparison to one with less material and a smarter design. The worst case scenario (aside from doing nothing at all), is a very high density absorber filling the entire area. There isn't an easy to define limit here because there are several variables. If there is no front reflective baffle, it's not a baffle wall but rather a very large absorber. Both are very desirable.
  15. If I were using this driver in a home system, I'd use a sealed enclosure which gives you 80 Hz extension, perfect for working with a sub. Smaller size doesn't just keep your wife happy. It's easier to work with and as you start to look at making the box inert with bracing and thick walls, the weight is not so prohibitive. A sealed enclosure also allows you to fill the entire enclosure rather than just lining it. No matter what you do, a 15 is big! Even in the smallest possible enclosure, it's a beast! You can squeeze out another octave with a ported design - many people think this is what they want before they hear it. But unless you have a lot of midbass boost from the room, it's probably not going to be very satisfying or full bass. In a home theatre it's a no brainer. Even in a music system, I'd still go with "compact" sealed, using your sub to set the bass level as it sounds right. 45L sealed with light fill should work well. If you really must have as much extension as possible, 150L tuned to 40 Hz reaches 40 Hz. You don't need to go any larger unless you are looking for an EBS (extended bass shelf), which trades box size and max SPL for extension. 100L tuned to 39 Hz gives you 50 Hz.
×
×
  • Create New...