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Red Spade Audio

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    Paul

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  1. In terms of SPL capability, it will be similar to a sealed 12" sub with around 12mm xmax and a 500W amp. The Elac will likely have more midbass output due to greater piston area but in the bottom octave, a 12" with higher excursion can provide greater output where output is excursion limited. The dual opposed mounting of the Elac helps with cabinet vibrations but having drivers firing up and down also reduces the effective excursion slightly over time. The 3D cut away model of the Elac shows the voice coil overhang, which gives us some idea of xmax. For comparison, here is the Peerless XLS, which has an xmax of 12mm. This is a fairly crude guesstimate but this should give a reasonable idea of what you could likely expect. The xmax of a sub driver is the one way excursion, from rest to the out or in position. It can vary from 4 - 32mm + but most are 12 - 22mm. A 15" sub has a clear advantage over both, assuming all else is equal. The 15" needs to be bigger to actually deliver on its potential and also keep in mind that it will also generally be more expensive. Keeping in mind also that some big subs are like power tools - impressive on paper in terms of how much air you can move for the price but not always impressive in terms of getting clean and accurate bass. This is the other aspect of performance.
  2. DEQX have been doing this for a long time. At one stage you had to pay for it but last I heard they offer this as backup support. We've been doing it for around 6 years although more people ask about room analysis and bass integration. I know this urge very well! As I see it, there are two basic categories here: A: Fundemental things you want to get right the first time - set and forget B: Things you can fiddle with forever without messing up the fundamentals If you engage someone then you might have them to do A and then tinker with B. There are many ways you can do that, without having to get them back over and over. If you have a way to tweak the overall shape of the response, that's probably the best thing to adjust to your own taste. I will often show clients how to do this on their own in a way that would mean there is no need for me to come back.
  3. You can do it, but should you? Do you switch between music and home theatre? In many cases, inexpensive subs are designed as ported to meet a certain price point. You can then use a cheaper driver that has limited excursion and power handling - essential a driver more like a woofer. It might only have a 100W amp and tuning around 30 - 40 Hz. Let's suppose you have 35 Hz extension. Block the port and you move this up one octave - to around 70 Hz. In a small room with strong modal midbass resonances, this might actually sound better than the ported version that is able to put more energy into those modes. In some cases, this might actually work, but you are giving up headroom in the process. Now let's suppose you have a more substantial sub that is tuned to 20 Hz. This is quite different. With music, the port will see limited action and in the midbass, the output is coming from the driver, so in this example, the difference is less than you might expect. Seal the ports and this sub now has 40 Hz extension. This is enough to engage the same modes in the midbass as the ported version. If you have a bass problem, plugging the port is usually not the best solution. The tools that work best are position (sub and listening position), bass traps, EQ and filtering.
  4. It sounds like you are talking about two problems: 1. Excessive bass 2. A wall that appears to be vibrating Where you have plasterboard vibrating enough that you can hear it, plaster against framing, bass traps won't help. If you have too much bass for your taste, bass traps typically also won't help. Generally bass traps in the front corners won't sufficiently change the frequency response enough that you would reduce excessive bass. From your description you most likely have some peaks caused by room modes. When you treat a room with bass traps with full range absorption, you get three changes: 1. Bass becomes tighter, with improved decay characteristics 2. The low midrange region becomes cleaner - less muddy 3. The overall reflection levels in the room are reduced - the brighter the room, the most obvious the change Acoustic panels on the front wall can have an impact on the sound stage, especially with regards to depth. It's fairly safe to add bass traps to any room. It's virtually always beneficial, the exceptions being only rooms that are already too dead. However, with full range acoustic panels, not every step is in the forwards direction.
  5. From a sub design perspective, it doesn't matter much, as Dave pointed out. From an integration and aesthetics perspective, it can make a bigger difference than you might think. Moving a driver by as little as 300mm can make a difference. So the position of the driver on the baffle matters as much as it prevents or allows you to get the optimal position. When a sub gets larger, this starts to matter more.
  6. Thanks for the mention Mike. This may surprise you but I'd say of those who call on the phone about acoustics, very few are tyre kickers. I measured a room recently where the entire ceiling had been treated. In this particular case, it was actually too much, resulting in a room that measured more like a studio, but this does show that you can do a lot to tame overall reverberation levels in a room with just the ceiling. Very often the ceiling is neglected in room treatment. It's odd in one sense that so many people consider carpet important, yet don't think at all about the huge untreated ceiling above. The downside with ceiling treatments is that it adds installation challenges. The upside is that you have a very large area that you can treat, usually with fewer obstacles. Going back to your first post where you mentioned speakers, here is something people that often happens in these types of rooms: the speakers often are very close to the wall, either side of a large entertainment cabinet. If you can move the speakers out from the wall behind them, and sometimes the couch a little further forward, this adjusts the ratio of direct to reflected sound. This is a ratio that you can adjust with both treatment and speaker placement. Yes, I know this involves SAF challenges but in rooms like this there is always a conversation in which we try to find the sweet spot. Very often in these rooms you will end up with a more reflective room that the ideal. In many cases we can get a significant improvement with this one adjustment alone. In some cases, you may find you can get a similar result that may have taken twice as much treatment. With this in mind, isn't it worth seeing how far you can push your luck with speaker placement? Now keeping this in mind, you might also think about having speakers that are not too easily toppled over! Before you make any decisions about how to treat a room like this, you need to consider: 1. What specific problems are you aiming to solve? Hint: it's not as simple as reducing reflections. 2. What bass challenges do you have? Some problems you can solve with trial and error - it's not ideal to do it that way but with bass, you really can't. 3. Aesthetics - do you want panels that blend, like say white panels on the ceiling and upper parts of the walls. Do you want panels that could pass as decoration? In a room like this, you might think about both. In some rooms, you can set up bass capable floorstanders and get great bass. In others, there is no feasible speaker placement that will work well for bass. This is where a specific number of subs in specific locations can become the only effective tool to make great bass possible. Here is an example: The black line is how some very large floorstanders measured in a room very much like this one. You can see the speakers still have some low bass output but in terms of tonal balance, the room is out of whack. The blue curve shows the best sub position I found in this room, with EQ applied - yes I know, that's cheating. The sub is tiny compared to the floorstanders but is has the advantage of being able to go in the ideal bass position. This solves the bass problem, but you may also notice, the low midrange is missing. What this suggests is that very often these kinds of acoustic challenges require solutions that go beyond traditional approaches.
  7. Thanks for the mention. Yes - still offering remote consulting services, help with bass issues is still one of the most common requests.
  8. This can easily backfire in a couple of ways. Firstly, SVS subs are very good in performance, value and sound quality. I've never come across an SVS sub that has made my job difficult in setting them up. By contrast, I've worked with alternatives which look impressive on paper but end up being hard to work with. When you start looking for subs with twice the firepower and the same price, this won't always be a forward step. Secondly, a second sub can work against the first. You won't be able to identify this easily unless you understand how to test and integrate subwoofers with acoustic measurements. It's quite common that what you describe is caused by room acoustic issues. Sometimes a second sub can improve that situation, where a second position overcomes a problem. In other cases, there is no available position that actually delivers a real improvement. Two subs in the same position means + 6 dB max SPL, which in the bass typically delivers twice the perceived impact. It's actually quite significant. In different positions, the subjective impact can potentially be much greater than expected. This occurs where you have significant dips in critical regions. In some cases, a second sub may deliver + 6 dB in the low bass and overcome a broad 20 dB midbass dip. Where this happens, the second sub can offer a dramatic difference. But this does require a particular process. Some good points by Al here. Don't overlook what you have right now. It's more than likely the deficiency is not related to the sub itself.
  9. There is a place for pro audio components in hifi systems, especially when it comes to power amps for active woofers and subs. With regards to valve amps used in pro audio I'd be quite cautious. In my experience, good reviews are not always a reliable indicator. I've experienced many products I'd rate as mediocre which were highly rated by many audiophiles. It's not always safe to assume that a product you only hear good things about will be one that you have a good experience with. Having said that, in the past I had good experiences with Behringer A500, which is a studio amp at a ridiculous price - around $350 before it was discontinued. I've not tried it's replacement which is an entirely different design. I've worked with a lot of pro amps like Behringer, Crown, QSC, Quest among others, both in pro and home audio systems. They may not be the last word in high fidelity and their fans often mean installing them in another room. They are ideal for active systems, driving a sub or a woofer. You get loads of power and the ability to drive difficult loads reliably. In the bass, the extra headroom can translate into bass with greater authority. This is where a hifi power amp may be clipping without any obvious penalty, until you hear a comparison with a much more powerful pro amp. It may not sound louder, it may just give you the impression of meatier and more authoritative bass. What you are hearing is likely just a pro amp which is not clipping.
  10. If you want to create a "rock specialist" system, it's a good idea to be clear on exactly what you want to achieve. That's is your best chance of being able to sit back and just grin at the result ... or head bang, or fist pump if that's your thing! Audiophiles are spoilt for choice with speakers but in my opinion, almost everything is "good but not great" when it comes to rock. If you want to really rock, here's the things I'd argue are most important: 1. Dynamic range - essentially this means the ability the deliver high SPL. On its own, this would mean pro audio speakers but these often have problems in other areas. 2. Tonal balance - having the right balance in your room is critical. Many audiophiles sell their gear or unwittingly buy new equipment they like better, in some cases purely because it gives a more favourable tonal balance. A lot of people prefer "warm" speakers for rock, which is one particular tonal balance. One of the big problems here is that the bass is often messed up by the room. If you don't have any way to control the bass response, you could be dealing with boomy bass, overly lean bass, uneven bass or even all of these together. 3. Accuracy - a certain amount of accuracy is universally needed but quite often speakers that people like for rock are actually fairly inaccurate. 4. Effortless - a good rock system needs to play loud without fatigue. It's easy to be unaware of the ways in which your system actually limits how loud you can listen without any sense of strain or fatigue. In working with clients, I've come across a few surprises at times, where changes in the system allow them to enjoy listening louder. It seems to be related to removing things in the system that create discomfort and fatigue. You can achieve this by: treating a room using tweeters with better behaved breakup modifying crossovers (many designs are not well suited to higher SPL) altering the tonal balance, often with more bass and in some cases adjusting the shape of the high frequency response One of the big questions is "how loud do you listen?" There is a certain threshold beyond which many tweeters start to become particularly strained. This is where you might have a silk dome that sounds smooth and refined at moderate levels but when levels go up they start to become strained. At this point, most people just dial back the volume, because here things start to fall apart and it's no longer enjoyable. We tend to think "that's just too loud." But there's an interesting comparison not many have experienced, where you try a speaker with a good compression driver and waveguide. At lower levels, you might prefer the silk dome but when you crank it, this is where a shift occurs. This is where a well sorted design with a compression driver can take you to the next level. With the right design, you can actually enjoy your rock music at a much louder level, before it starts to become too much. This certainly isn't true of all compression drivers or all horns. Far from it. There are so many horns, waveguides and compression drivers that have the opposite effect - making your ears bleed. Sensitivity isn't the answer. There are many speakers with high sensitivity that behave badly even at moderate SPL levels. There are examples of every type. Hence it's a mistake to think that high sensitivity means "good for rock." It's certainly not the case. I've heard so many that have high max SPL on paper, but you just can't enjoy them loud. I'd suggest there isn't a simple answer that will deliver a system that will really rock. But I'd argue these are the most important parts: 1. Speakers paired with a suitable amplifier 2. Some way of adjusting the tonal balance 3. A strategy to achieve accurate and balanced bass 4. Acoustic treatment A lot of audiophiles don't want to hear this at all, but very often a sub is an essential part of a good rock system. Sometimes you can get lucky and find that big speakers with a lot of bass potential work out just fine without a sub. However, I see so many examples where this just doesn't work at all. It's almost never the fault of the speakers. Quite often very large and very capable speakers simply don't have enough bass in a particular room, regardless of placement. Sometimes it's just a feature of the only room you have to work with. More often than not, a sub in the right place, when calibrated correctly, will dramatically improve not just the bass but the entire tonal balance. In some cases, a speaker that sounds slightly forward comes into balance when the bass is lifted with a sub. But I should also caution that as Satanic has menioned, yes a sub does introduce challenges. All of them can be navigated but it's not a simple case of plonking down a sub and experiencing bass bliss right away.
  11. He is looking at the default view in Win ISD which shows the small signal bass extension. You are zooming in on the bass extension you would see with 1w input if you measured the speaker outdoors ground plane or nearfield indoors. Move across to the SPL tab with 1w input and you will see that 0 dB equals the sensitivity of the driver as modelled by Win ISD. Often it will be lower than the spec sheet.
  12. Sorry SS, only just saw this, over a year later! I've used glue and screw with construction adhesive in the past. Quad in internal corners isn't a bad idea. If I were doing this now, I'd probably cut a rabbet joint which would then remove the waxy surface at the join. I wouldn't sand it because that's a slow and tedious job. A straight cut bit on the router is also an option.
  13. Ideally it's best to determine which positions with measurements and that informs the form factor you need. There's many ways to approach this, but here's one idea that makes sense for dual HT subs in a small room. Let's say you're placing them in the front corners. Let's suppose your goals are: reasonable enclosure size (<150L) modest footprint (max 400x400) extension to 20 Hz or lower max SPL below 30 Hz (in a HT this really determines the max real world useful output) These goals point towards a 12" ported design. Consider any of the Dayton 12" Reference series. 15" drivers require a larger footprint and a bigger overall footprint. Ultimax need larger enclosures. They tend to suit US style DIY subs - huge ported boxes tuned low in big rooms. So as a starting point, you'd be looking at an enclosure that might be 400 x 400 x 1200, standing up in the corners. Ports then become fairly simple. A pair of 100mm PVC straight ports - about 1m each with no bends. This recipe would work well with Dayton Reference 12" (HF). There's always that risk! Car audio drivers often work quite well for horns but they aren't typically my first choice for a HT sub. Lack of published TS parameters is one issue and often they are less than ideal for a HT sub anyway. Keep in mind that if you use pro drivers with high sensitivity, they require very large enclosures to achieve good bass extension. Quite often twice the volume or more, so you start to move into the same volume you might use with a horn. It's not the first recipe that I'd consider for a small room. When it comes to sub drivers and DIY sub projects, you really are spoilt for choice. Whatever you choose, keep in mind that it's actually other factors that make or break the final result - position, room acoustics and integration.
  14. Generally in a room like that you have excessive midbass above ~35 Hz. This comes from strong room modes here and you are forced to have speakers, subs and listening position near boundaries. Even modest sealed subs will sound impressive in the midbass, where most of the action happens. Below ~35 Hz it's an uphill battle. It's a good idea to first test all your potential positions. Ideally, lock in sub positions before you even look at sub designs. Now consider this. Around 30 Hz, a 12" ported sub has about the same max SPL as a sealed 18" where both have about the same total box volume. Assuming all else is equal. Below 30 Hz, the ported sub has a 6 dB advantage and above the larger driver has a 6 dB advantage in max SPL. This applies fairly well if you are comparing similar drivers, like say the Dayton Reference range. In a small room, the 12 actually makes more sense. You can make it tall to achieve the volume, therefore taking up less floor space. And it also provides more output capability where you need it more in a home theatre. Then again, sometimes it's not just about what "makes sense" logically. Sometimes you just want an 18! Along with Ultimax, also consider Reference series, which is a bit more versatile. Ultimax have higher excursion and generally require large enclosures.
  15. An acoustic difference? If you have equipment that is sensitive to vibration, then isolation is the critical factor. Here the materials and aesthetics are insignificant in comparison to having isolation mounts that are optimised for the weight and relevant frequencies. Here's what many people forget - the rack itself along with the equipment has a direct impact on acoustics. The worst case scenario here is where many people start - speakers sitting on top of a large entertainment unit, against the wall, no toe in, everything crammed together. It looks and sounds crammed in. Now move across to a minimal rack, placed for minimal impact, with speakers better positioned (usually with breathing space on all sides and toe in) ... now this is a big leap forward. It's less about the rack itself and more related to letting the speakers breathe. Very often when the rack is obtrusive, the speakers are forced into positions that hold the system back. There's always compromise in a living room system but when you take this as far as you can go, the rewards can be dramatic.
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