Standard-Setting High-End Audio Equipment You Need to Hear to Believe

By asking what the manufacturer is open to telling you, how much full disclosure there is. If there isn't much for comparative data, is there a system of guarantees that surpass standard warranty limitations? The system ability "tell all" is compression. Compression is not the reduction of output, it is actually the audible symptom at 1 dB that the driver is starting to suffer in the ability to control flux and heat within the motor assembly. With compression, intermodulation distortion and intermodulation compression (laws of physics support that this statement is true) will start to runaway, first in the fidelity aspect will be clarity and a sense of ease of sound. After that, the sound will thicken, then it will clearly be audibly suffering. Look for a speaker manufacturer that clearly indicates the compressive limits and character of their equipment, and if it is 1 dB or less across the entire bandwidth of the speaker, then you can buy with confidence.

Have you ever bought an audio system and at first it sounded great, but the honeymoon seemed to fade away after a few months? Did you feel there was something missing in the sound, but didn't know what it was? Did you then go to the manufacturer and ask what the problem may be and their reason was that "you got used to the system" and suggest you buy either more or bigger speakers to go louder? This is common practice, and at it's root it does not solve the problem of making the audio satisfying. It tries to solve a "its missing something but I cant tell what it is" problem by calling it an issue of not going loud enough. It's simply the wrong tool for the job. The first step would be to discuss your sound system with a qualified audio calibration specialist and see if there is room for improvement in setting up the system so all of the speakers work in unison. This is a huge step that so many enthusiasts overlook or simply do not know enough about the work to have any real meaningful impact for the better. The hard truth is that system tuning is not an easy job, and automated systems might get you a measure of the way to your goal, but if you feel like there is something not quite right, then generally your ears are telling you the truth. Your ears and brain know what a realistic sound should sound like, so trust them and use a skilled professional to help you find your perfect tune.

The second step to making your current system sound better is to seriously analyze the level of fidelity your system is reproducing. As mentioned in the part 1, if your ears and brain are telling you "that doesn't sound right", they are not lying to you. Take some content and play it on a system at a quiet level, and then ask yourself if you can hear everything as though it was really happening in front of you. Then play that same content on another system of some kind or at a different volume level (quieter or louder) and see if that song or show sounds more correct, more real... not "better" but more real. If the content sounds more real on one system and less real on another, or its realness changes with output level, then you have an issue with the quality of the sound. So don't get duped into thinking you have to buy more gear, you can find nice sound improvements in a number of areas. One would be to discuss with the calibration specialist mentioned in the previous FAQ and see if the system you own is known for its fidelity and sound quality. A second solution would be to add acoustic treatments to the space. If these are not in your future, then you would need to consider going to some extremes in technology to handle the specific conditions of your room, something we are well versed in. Please feel free to contact us to discuss.

LDLC stands for Low Distortion Low Compression. This is our engineering model and it forms the standard for our quality control measures. What it means is that every speaker we build will not distort or compress until it is within a safe margin from the mechanical limits of the driver motor. The allows the buyer to know they are buying a speaker that returns its value and ability by giving the user as much of the stroke of the motor to use in beautiful, clean, high quality sound playback. LDLC and Speaker Competence Generally, it is accepted that people learn and absorb information differently, and lets be real here, LDLC does not fit the normal conversation about audio. In fact, it ignores the vast majority of it. A way to discuss LDLC audio came to me when a customer was asking which was better, a tower speaker or a bookshelf speaker when a subwoofer is used at a crossover point that is higher than normal. The typical answer would be “it depends on how much you are willing to spend and how loud you want the speakers to go”. More audiophile-ish answers would revolve around “what is the application, but more specifically how is the application expected to perform”. In other words, “what do you want it to do?”, then use audiophile terminology to describe the sound you want. To me, that feels ambiguous, vague, and any number of other words simply due to the fact that terms can be interpreted differently from person to person, but mostly it is an answer that I hate giving because it is not technically correct. The truth is that the technical aspect is more simple than one would assume. The answer, in LDLC terms, is the speaker that is the most competent. And to me that competence is measured by the lowest distortion, lowest compression, and greatest efficiency across the bandwidth. This is how we engineer, design, and build our speakers. The issue is that these aspects are hard to identify by the standard way of discussing speakers, so they are given terms and phrases to help encapsulate these engineering properties. Think of it as cooking: all of the ingredients are ratios of each other, and in this recipe there is distortion, compression, and efficiency. All three of these, in different proportions make up the verbiage used in popular reviewer terminology. We feel that this compartmentalizing of physics into terms that are descriptive is fine, however there is a far more simpler way to discuss audio when distortion and compression are retained and minimized to inaudible levels, and efficiency is maximized to the most advantage it can have on the design. So we made a guarantee in place of popular terms and phrases. This guarantee is found in the LDLC whitepaper, and it's called the F1 threshold curve. It guarantees that distortion and compression will not be audible for 70% of the stroke length of the driver, this is known as Xmax in driver engineering terms. This is important because most drivers have a very difficult time getting to that point due to the standard of engineering that is most popular, which is based on low demand measurements and results, these are known as TS parameters. Now when the driver is clean for 70% of its travel as minimum, the removal of distortion and compression and increase of efficiency is prioritized, you can automatically equate that to competence without over engineering. We aren't simply just over building drivers, we are actually engineering them to be competent. Over building would be seen in the efficiency metric and easy to spot. So what exactly does this result in? First of all, the majority of audiophile phrases and lingo can be tossed. Some might find that difficult to deal with, however the popular terms used are simply a way of describing the effects of different ratios of distortion, compression, and efficiency. The conversation narrows to dispersion or width of the sound stage which also coincides with imaging and projection. From here the discussion is pretty simple. Let me draw some parallels for you: Imaging and projection: good imaging and projections will track with sound and kick the sound into the room, giving it a very 3 dimensional sound, in other words, surround sound without the surround speakers. Dispersion and sound stage: This has to do with the shape of the sound wave coming off of the driver cone or membrane. What this needs is a balance of efficiency over bandwidth and low compression. And not only low compression, but compression that is very linear, in other words, flat across the bandwidth. Important to note, dynamics and dispersion trade off with each other. If you want lots of dynamics, you have to sacrifice some dispersion and the other way around, which ultimately results in riding a fine balance of the speakers abilities. So now talking about audio is very easy… there are only a few things that affect the character of the sound, and it is entirely possible for a bookshelf speakers and tower speakers to sound and behave identically with the only difference being the raw output ability, how loud they go. And what this means is that it is much easier to buy a speaker for your needs, knowing that you will get the same quality sound with variations in sound stage and output abilities to suit your taste.

Yes they will. We engineered our subwoofers to be used in a large variety of systems and they can even blend with other manufacturers' subwoofers very well.

Not to worry, we have you covered. You can add a Harbottle Carbon Series subwoofer by using a splitter on the left and right channel, and running a left and a right directly into the two inputs on the subwoofer. From there, our advanced DSP will sum the two signals into a mono subwoofer bass signal and give you the most optimum performance available. To blend the subwoofer with your stereo system, simply use the display interface to adjust your crossover point, gain, delay, and all eq filters, to get your perfect sound. We favor versatility and want our clients to have fun using their audio gear, so we have made user adjustability without any constraints. Tune and tweak my friends... or don't, either way you want to approach it, we have you covered.

Ah, the everlasting question in audio. It is well founded that subwoofers help audio, but in some stereo purist circles they are still viewed as heresy and rightly so. Here's why, with minimal audiophile lingo. Competence. A speaker being asked to perform 20 to 200 Hz is a huge task. It is noted that many speakers are fully capable down to low frequencies but we need to ask where the useful limit is. This has a lot to do with the designed purpose of the speaker, however, the simple fact is that most stereo left and right speakers have a very difficult time producing frequencies below 100 Hz. This is not to say that there aren't any that can, but rather the ones that can (in general) can struggle with the task. Then there are the truly exceptional speakers that can hit 60 to 80 Hz and not flinch. So in terms of speaker competence, does your audio system sound real? If it is hazy, heavy sounding, or lacks a certain "something", you probably need a good quality subwoofer to ease the burden of bass from your main left and right speakers.

This is because bass frequencies are very very long, and they require a lot of driver stroke to produce. Surface area of the cone is only a small part of the equation, and in reality has very little to do with high quality sound because the duration of time the cone & coil has to spend on either side of the 0 degree stroke mark is simply longer. So it makes perfect sense that the driver should be biased towards complete authority over the stroke in the frequency bandwidth it is supposed to reproduce. The more stroke you have available, the more SPL, the deeper the driver "should" be able to go, and the better the sound. All of this takes a lot of engineering that is far different, and possibly more complex, than any midrange or tweeter driver, and that engineering takes money. So to make sure you get the most value from your subwoofer or speaker, make sure the manufacturer indicates that you can use all of its stroke without adverse effects of compression.

This depends on design and application, which is a complex topic. For this reason we like to deal with prospective clients one on one. Please feel free to contact us for a no obligation consultation. For a generalization, we will always suggest buying the best main left and right speaker you can afford using the prerequisites on advertised compression as your barometer to tell if the speaker is engineered for audio performance. Once you are satisfied with your audio, then look at getting a subwoofer to supplement the low end bass.

It's marketing lingo for the accuracy of audio playback to the original recorded content. It is also accompanied by a wide variety of verbiage called audiophile terminology that describes the character of the sound. However, all of these terms can be reduced to two very simple engineering terms: distortion and compression, specifically the lack of these two things. Distortion is usually measured in harmonic which is the mechanical noise of the unit. This is a very simplistic view that has very little to do with fidelity other than the point at which the mechanical components of the driver reach their limit of linearity. The bigger indicator of fidelity is compression. At the point of audible compression, approximately 1 dB, the subsequent output that follows with each increase in applied power to the driven unit is now compromised and sound will degrade accordingly. This is due to the fact that the components of intermodulation distortion and intermodulation compression are a direct result of the compressive behavior. In most cases this is a result of flux modulation and suspension character working in concert to exacerbate intermodulation effects. What this means is that compression is not simply a loss of output, it is accompanied by distortion and distorted audio behavior. For your audio system to maintain fidelity, it must exhibit minimal compression.

Setting up a Carbon series subwoofer is actually quite easy as most AVR systems have the ability to tune and correct for room related anomalies. As each subwoofer has a number of presets available to the user through the display interface, it is quite easy to get your subwoofer set up and optimized for your listening preferences. ​ What you will need: Stand alone measurement system. I recommend Omnimic V2 by Dayton because it is fast. You only need track 2 (omniphonic short sine sweep), and you can run that test track for 10 min and see the result of your adjustments live as you change settings without having to reset and sweep each individual setting change. It very easy to see an improvement as it happens. Patience. Read your AVR manual and source online publications for in depth information. ​ What you want: You want to be able to fine tune the auto calibration after it is done. This will allow you to use the base line settings as a datum point and then improve from that point. Make sure that your AVR can do that. ​ Rules to follow: Use as few EQ filters as possible. I shoot for 4 filters at the most. Cut in EQ, then boost back what was cut in the gain If you have a null, cut around it in the EQ, then boost back the overall in the gain to restore output. ​​​ I use a ratio of 6 dB cut to 5 dB gain boost. Boosting in EQ will hit the limit faster in the amp at that one point. This means that the amp is having to work harder to cover more changes within its own frequency response. This can make your system sound stressed and yucky. Steps Match your levels from your mains to your sub/s. Run the sub/s to the upper limit of their advertised response. If it advertises 100 Hz, run it to 80-100 Hz. ​​ Rough in the delay. Set your delay up according to the physical distance of your speakers from MLP. This will not be perfect because it does not account for system latency, but it will get you close.​ The goal is to match the speakers so all the sound hits the MLP at the same time. Provide a gap to the main speaker crossover. If the sub is at 90 Hz, then set your main speaker to around 105 Hz and adjust the slope and move it up and down in frequency until you get a nice big sum (bump upwards) in the crossover range. Generally you will see about 15-25 Hz gap between the sub and the main speakers.​ You want to look for the smoothest transition with the most gain. This is free gain without any amp stress or extra stroke being used by the drivers, so the more you can get the better. Repeat steps 3 and 4 for the best possible sum; this will be a combination of timing delay and crossover work. So you will have to work both in smaller increments to get the best possible sum. Be patient. Now that you have a big sum (bump upwards) you can be sure that you do not have any cancellations between your main and your sub. Write down these settings. Now tune or auto calibrate your system. See if your system will allow you to adjust the crossover after the auto calibration. If it does, you can run the auto calibration and then adjust the settings on the crossover and do some manual set up to really dial in your sound. Once these steps are done, listen to the system for a week or so, and revisit the set up to see if you can get any more tuned performance from your system.

In this section we will be discussing how to compare subwoofers in terms of all three performance metrics: output, compression, and distortion. Currently, the only tester that we have found that measures output, distortion and compression is Data-Bass. There may be other third party testing companies that go this far, however we have not found them as of yet. To accurately compare subwoofer systems on Data-Bass, you need to compare all the factors: not just CEA2010 burst Output. Often key elements of Distortion, and Compression are overlooked simply due to the complexity involved in correctly understanding these results. To compare distortion levels at an actual output level, you cannot simply compare the same nominal sweep levels (ex. 120dB to 120dB) because that does not factor in response shape or compression. This leaves out critical information and assumes that the drivers have the same response curve, and the same compression levels. These assumptions skew result interpretations greatly and can make systems that are wildly different seem very comparable. ​ What this method does: This is a way of normalizing the attribute of sound that you are interested in and seeing how the other attributes of sound affect it. By the end of this example you will be able to compare either on of the three aspects of sound (output, distortion, compression) to the other two, inclusive. Essentially we are providing a way to qualify what you are hearing. at A frequency at B dB SPL, we are hearing X distortion and Y compression at A frequency at X distortion, we are hearing B dB SPL along with Y compression at A frequency at Y compression, we are hearing X distortion at B dB SPL The following set of instructions can help you understand and draw accurate comparisons from the massive amounts of data presented on Data-Bass, and in fact, the principals found within can be applied to any third party test that measures all three metrics of audio performance. To compare two different subwoofers: Get a pen and paper for making notes and open a spread sheet Open two web browser windows Go to Data-Bass in each browser Select the systems tab and choose the two drivers you want to compare, one for each window Scroll to the bottom of the page and select "Measurements" Select "Extended Charts" Scroll down to "Long Term Output Compression" sweep chart Choose a frequency - I usually start at 10 Hz and work my way up from there Pick the appropriate sweep where the output matches (or is close) between each subwoofer Note that sweep and output Now click on the "Multi-series Charts" tab Look at the "Total Harmonic Distortion" sweep chart Now compare each driver to their corresponding sweep at the frequency you have chosen This will tell you the actual distortion as it relates to real dB output Write the THD down as they correspond to each driver Go back to "Extended Charts" Now scroll down to "Compression Magnitude" This will tell you how much the driver is compressing at the actual output, at your chosen frequency specific frequency Write these compression figures down as well Work your way through the frequency range to get a good idea of what each driver is actually doing Now compare your chosen drivers Reading the charts this way tells you a few things; distortion as a function of output, output as affected by compression, all at a predetermined frequency. dB @ xHz = y compression and z distortion Lets do an example: Open two web browsers and go to Data-Bass.com and select the "Systems" tab. Select the GUJ18v1 sealed for browser 1 Select the Funk 18.0 Passive for browser 2 These two examples are Harbottle product to avoid the appearance of defamatory comparisons. Select "Extended Charts" Scroll to "Long Term Output Compression" Look at the 20 Hz mark. Look to see where they match output In this case the 18.0 is putting out 103.4dB on the 120 dB sweep The GUJ18v1 is putting out 104.5 on the 115 dB sweep Now go to the "Multi-Series Charts" tab Look at the "Total Harmonic Distortion" sweep chart. 18.0 will be on the 120 dB sweep and the GUJ will be on the 115 dB sweep, both at 20 Hz. 18.0 = 17.69% distortion @103.4 dB GUJ18v1 = 16.8% distortion @ 104.5 dB Now we can safely assume that at the same output level, the GUJ should produce about 2.5% less distortion at 20 Hz. We can work the opposite way and say that at the same distortion level, the GUJ should produce about 2 dB more than the 18.0. Go back to "Extended Charts" Scroll down to "Compression Magnitude" and see how many dB you are losing due to compression. Both systems are compressing around 0.5-1 dB at 20 Hz. Repeat with all frequencies that you are interested in studying. ​ This method can be used to create your own graphs in any spreadsheet software for a visual representation of the data as it relates to including all audio performance metrics. Important Notes. This method takes as many variables as possible into consideration, but not all things are equal. There is one aspect of sealed subwoofers that one must take into consideration when comparing systems, that is box size, materials, and construction methods, as this component affects distortion at a given output greatly. One will notice after making comparisons with high performance systems, there is a correlation to how much output you can get with a certain level of distortion with a given enclosure size enclosure, dB @ THD @ CuFt. As the enclosure gets smaller, all else being equal, if you maintain output via adding power, distortion will go up. You can combat this with driver/system design however there is a limit, and eventually the air spring distortion of the box becomes the overwhelming factor in the resultant distortion. No amount of engineering can overcome this physical law. ​

Knowing where the limit of the driver and/or the amp is is challenging, but not impossible. The Xmax Guarantee allows you to safely design to a specific stroke limit and dramatically reduce guesswork and unknowns. First lets discuss design and set up. Speakers have areas of high efficiency and areas of low efficiency. This follows the impedance curve of the driver. At a given power level set on your amp the driver will use a lot of the amps power (volts or amperes) to produce certain frequencies, while other areas of the bandwidth will use very little power. Those parts that have an easy time (more efficient zones of operation) can be eq'ed more aggressively if they are not at the limits of stroke, but we need to know where the driver is in relation to its maximum excursion threshold. So this need is best served by getting a full picture of what the amp can do when paired with the driver in question. This is how to go from native response to eq'ed response, aka EQ profiles. After you have reflection free eq'ing done, then you can go to room corrected response. This does a few things: 1) it allows you to drive the sub based on your taste before the room becomes a factor, 2) the room can be dealt with separately while knowing where the real limits of the driver are, thereby assuring you that your room correction will not go past the limit of the subwoofer. However, you can't get to that point without knowing what your amp can actually do when combined with its very particular load (impedance curve, aka the sub). This is the design work. Knowing where the limits are means getting ground plane measurements outside (reflection free) and finding the limits of the sub and amplifier using measuring tools. The workaround would be to verify using the Xmax guarantee (which is the biggest difference with Ridge LDLC subs) with your simmed power at Xmax, then find the power level that fits and allows for the best tuning. This would side step going outside for ground plane measurements and get you closer to Xmax operation. But you have to trust your meters, they have to be on point. And this is why doing both outside ground plane measures while verifying with a meter is the best way to know 100% what is going on. You can test this by simming the tested data-bass units and then stacking those sims against data-bass results. This is the verification process that the Xmax guarantee actually works. ​ Here's a simplified step by step: Sim the driver at Xmax. Record sim power at frequency intervals, such as CEA 2010 intervals. Run the amp and check volts and amps with meters (don't use cheap meters, you need to trust the reading) using waves, not sweeps. Go up to highest simmed point on output power running the amp loaded (sub hooked up) and record amp settings as you move up the bandwidth. CEA 2010 frequency steps work good for this. Example: At Xhz the sim says 20 amps and 55 volts. But your amp hits 20 amps at 40 volts at that frequency. Stick to 20 amps as the max, as that would be the amperage limit of the driver and pushing further has risks. This is also an indication of how far your sim power deviates from the ability of the amplifier. Use the amp setting that gives the best tuning abilities (best headroom) to achieve the EQ profile you wish to have. Tune system for allowable amp output response (what the amp can do at the limit of the sub or vise-versa). This is math where you calculate tuning based on the amp settings and running waves at frequency points at that amp setting. Then tune based on calculated available power and calculated headroom based on close mic (approx. 2 inches around 70 dB measured driver output or you'll pop your mic). Create and save your EQ profile/s. Remember this is void of room gain. Set your limiters, if you have them. These can be voltage, amperage, or a protection lockout mode when the amp clips or thinks it sees DC voltage. This is your system protection. If you do not have a limiter on the output side of your amp, then the only protection it has is your EQ work and gain setting. Set the amp output level to the calculated level found in step 4. You can set your headroom level at this point by adjusting the gain up or down. Run response sweeps and correct for room response at MLP. Try to not EQ too much. Over EQing can result in overlap of frequencies fighting each other and sounding stressed. This is noticed by localization, lack of clarity, or a stressed audio sound. And your done, you're getting the most from your sub. If you are apprehensive of your work, cut the gain or get more aggressive with your limiter. ​ WARNING If you are not experienced in extreme subwoofers and DIY subwoofers, there is a chance that damage may occur to the driver or the amplifier. Harbottle is not responsible for any damage that may occur in the testing, implementation, or use of a Harbottle DIY product.

DIY subwoofer amplifier guide. Amplifiers produce power according to how they are designed. As they are measured in watts, it is important to know what a watt consists of.​ Watts = Volts (push, electromotive force, electrical force, etc.) x Amperes (current)​ W = V x I​ As you can get a total product (multiplication) from various numbers and combinations of numbers, so Watts can/may have multiple combination possibilities of types of power to arrive at that Watt number. It depends on how the amplifier is rated and what its design is. Add to this the amp can produce these components of Watts differently at different frequencies and output levels, based on the speaker load it is serving. Ambiguous? You bet. ​ Confusing? Also, you bet. ​ How do you overcome a vague rating and "know for sure"? By testing. Our drivers are tough, start off low and slow and work your way up until you hear distress. Observe your amp power, if it is limiting at the same time there is distress sounds coming from the driver, then there is a good chance it it the amp that is limiting first. Protect your amp. If the amp is producing less than 100% power and there is distress sounds coming from the driver, then the driver is telling you to back off. ​ The question is, what kind of power does the amplifier produce better, and what kind of power does the driver like?​ Our drivers like volts. So if you are able to get an amp that favors volts, get it. Amps that produce volts better and with more consistency/authority (again, not definitive, rule of thumb), may be more expensive, again depending on how it is made. This rule is a sliding scale, so there are grades/levels of "amplifier goodness".​ Does this mean that all inexpensive amps are junk? No, not in the slightest. It means that they will reveal their limitations sooner (applied voltage to the driver), and that means that there is the possibility that you might want to upgrade the amp at some point. ​ The good news is that you can always sell pro audio gear, it is never really a market that dies off due to it's diversity of applications. On the other hand, offloading a class AB will narrow your reach a bit.​ ​ Watts to ohms ratings don't matter when working with an LDLC driver. I know someone is going to yell "blasphemy" and attempt to crucify me. But just read this part with an open mind. ​ Given that we know that an amplifier produces both volts and amperes, what we are actually looking for is voltage drop from one load to another, typically 4 to 8 ohm nominal. If the amplifier only produces (as a for instance) 5 volts drop when switching loads, then the appreciable difference in output between a 4 ohm load and 8 ohm load will be nil.​ Amp Class Guide​ Here is where Ohms comes in. Ohms provide resistance and push back on the power coming from the amplified side of the amplifier. This affects how much and how fast the amplifier needs to work to make up power. Lower resistance (load, ohms) = faster power production. Class D pro audio amps are designed to produce volts more easily and are generally optimized for 8 ohm speakers (loads). Our suggestion is to contact the amp manufacturer customer support and ask them what driver load the amp is optimized for. Relay that information to us and we will wire the driver for that amp based on that information. If the manufacturer is not willing to play ball or if their published specs don't give us enough information, the best we can do is default to what experience we have, and that is an 8 ohm driver for pro audio class D is generally a safe bet, but there are exceptions to the rule. Class AB, get the biggest one you can get, send us the spec sheet, and we'll wire the sub for that amp. ​ Power Guide​ Our power ratings are done on Harbottle amps - high voltage capable of over 300 V p-p (peak to peak sinusoidal AC voltage), as per Data-Bass test results. All ratings are RMS and listed on the product page. If you want to conduct more in depth study of the M Series unit, simulate the parameters provided. ​ A word on limiters. You can run a limiter to protect a device from clipping. This can either be the amp itself if it does not have clipping protection built in, or the driver. So the limiter can protect the weakest link. If you run a low power signal to amp clipping without a limiter in place and the driver can be safe because the effective temp rise of the coil will still be within the thermal limits. So 1000 watts clipped hard will be ok for the driver. But will it be ok for the amp? That's a question that needs to be sorted out on a per instance basis. Now to get the most out of the driver with an amp at the maximum power rating of the driver, you will need limiters to prevent clipping the driver, otherwise the thermal limit of the driver can be exceeded and then you get the Back to the Future guitar situation in one form or another. The Amplifier User Guide​ Customers are using the following amps in no particular order and they are all pleased with their system results. Let your budget and desire be your guide. This is not a list of recommended amplifiers. This is a list of amps used by customers only. Ram Audio Crown QSC Sinbosen Behringer Powersoft Lab Gruppen Dynacord Speakerpower Emotiva CVR D-Sonic VTV Harbottle Targets to shoot for Output voltage: 140 to 300 V peak to peak. If you can run 240V mains power, do it. If you only have 120V mains and 15 amp circuit, that's ok, just go for a more voltage based amp. All Harbottle subs will hit 5 Hz with authority... the amp needs to be stable down deep. Below low teens Hz can stress an amp, up distortion, and throw it into DC protect mode. Bass is hard to make. If you are running it hard and the content is there, our drivers will produce it. The question of your room reinforcing it is another discussion about physics. I can't change the laws of physics. Reference the Funk 18.0 test results on data-bass (all of them) as a check for what is what. You will see a direct comparison between Pascal and Powersoft amps between those tests. The driver, cab, the builder, all of it is exactly the same except for the amp, and the differences is results are not exactly small. So why doesn't Harbottle pick an amp that will work and just tell me what to buy? The short answer is that I didn't build it, so I know as much as the customer on what amps will work and what won't. I only know what I use, and I only use my own amps. The long answer is that there is a lot more to an amp than just a wattage rating. Matching an amp to a passive speaker is a complicated job, and the more you know about the amp itself, the more success you will have. If you go off of wattage alone, you will have to test and set up your amp to work with your speaker safely. If you are not confident in this process, then you will have to accept the risks that come with DIY. ​ ​ WARNING If you are not experienced in extreme subwoofers and DIY subwoofers, there is a chance that damage may occur to the driver or the amplifier. Harbottle is not responsible for any damage that may occur in the testing, implementation, or use of a Harbottle DIY product.

Matching a driver to an amp seems pretty straight forward, but it is challenging if you go too far one way or the other. Here are some tips that can help. Inductance. This measure will show (relative to the rest of the parameters) what the driver likes for power: current (amperes) or voltage. However there is a "rough cheat" that is a quick indicator. The type of driver it is labeled as. If the driver on the manufacturer spec sheet says "pro audio" and does not mention using a sealed enclosure, and nominal ohms are higher than 5, then the probability of the driver liking a pro audio style amp (voltage biased) is higher. Now if the driver says "deep bass", its available in dual 2 or dual 1 ohm voice coils, and the inductance (Le) is higher than the counter part in the pro audio line up, and the manufacturer has a pedigree in car audio, then the odds are that the driver will prefer current (amperes). And this makes sense because cars are awesome at producing amperage, and buildings like arenas generally have a lot of volts available. So matching topologies to mains power supply is logical. Rated bandwidth. Just because a driver is being used for a purpose outside of it's intended design, doesnt mean that it will like it or sound good. So if you design a system predicated on "pushing the envelope" by pushing the driver or amp past its designed purpose, and you dont like the results, just pull back on it a bit and dial in the dsp closer to the manufacturer set limits. So now the question is, how do I know what amp delivers what power? We need to look at the amp spec way past watts. Remember that watts are only theoretical and in all honesty, they have very little to do with the practical limit use of the system. All systems have a limiting factor, be it stroke, volts, amperes, physical size available in the room (real estate), location, room modes, the list goes on. Watts are one of those things thats looked at as a definite, but they aren't. The thing that is the most real is the peak volts out, and it is easy to calculate. V=P/I where V = volts, P = watts, and I = Amperes (amps) So if the rating of the amp is 3000 watts, and the amp (current) rating is 30A, then: 3000/30 = 100V You just need to make sure you are calculating RMS or peak voltage, always use Peak values. An amp marketed as a pro amp and delivers under 100V p-p will generally be better at frequencies above 40 Hz and prefer ohm loads around 8 ohms. An amp marketed as a pro amp and delivers 150 to 300V p-p has a higher likelihood of being able to do more in the low end, but will still probably sound better from 25 hz and up. An amp the shoves out 35-70A will probably do well digging down into the infrasonic range (below 15 Hz). An amp that shows a 2 ohm "stable" rating and no 2 ohm watts rating will struggle down deep. That rating is code for "it can do it but it wont like it". Always look at amp ratings. If it shows a power watts rating at 1 kHz (1000 hz), ask yourself if it makes logical sense to use that amp down to 10Hz subwoofer duty. And, "is there any proof out there that this amp has been used and is being used as a subwoofer amp and what is its actual and in real life bandwidth limit?" A good example is the specifications found on any pro audio amp website like crown or behringer vs speakerpower. I have no allegiance to speakerpower, but their documentation is just flat out awesome. They spec details that are easy to design around, and full of great information that is centered on bass reproduction, so as you learn more, you can always refer back and pull more data as you need it. And in fact I have like 8 drivers predicated solely on their amp ratings and topologies. There is an idea that power is cheap. That's not true. Cheap power is cheap. It is hard to make an amp drive deep and produce wavelengths that are potentially hundreds of feet long. That is a long time to hang out on one side of the sine wave, and the longer the amp hangs out there, the more it looks like the amp is in DC, which is welding territory. And so the amp needs to be stable far below the lowest frequency the driver is capable of producing, recommend about 1/2 to one full octave. So matching an amp to a driver is about matching designed purpose of parts used, and then managing you own expectations by knowing that if you step outside those designed and engineered purposes, your total design (all the parts combined) starts to step into compromised performance territory. Playing within the engineered purpose will result in a good balance. If you would like to know more. I have a great FAQ on my website that covers a lot of topics from beginner to advanced that don't apply to any of my products or services, just a lot of good information for everyone. If you decide to look up my products, you will see that I break all of the above rules... pretty much across the board. My product is different and it is engineered that way. Feel free to reach out to discuss, I realize that this is not the place to plug my own product because you were asking for help in a how to but I feel I need to throw that caveat in there in case you look and then stack what you find against what I wrote, because a lot of it wont fit, especially my raw drivers.