AVI - How much digital? How much analogue?

[Labarum]

This must be one for Ashley, though no doubt others will want a say.

 

As I understand it Ashley's wonder boxes have a remote analogue volume control, which must be a big plus; but has it's active crossovers in the analogue domain, which must be less of a plus.

 

Why, Ashley, did you not go the whole hog like Meridian and have digital crossovers? I presume this was down to cost and complexity. Am I right that the advantage is in digital crossovers?

 

And am I right that a good analogue remote volume control is easy to engineer at lower cost; and, all things being equal, is probably the better technical option? What sort of analogue volume control is it?

 

[Ashley James]

Brian

The function of a crossover whether it be digital or analogue is exactly the same, therefore there are no advantages in going digital, only disadvantages. Then two DAC's are needed, one for each power amplifier or you have to use Class D power amps and these have a whopping 30-40dB more distortion than ours! You also lose the analogue input or have to provide another A to D convertor for it.

 

Going digital gives greater complexity, greater potential for unreliability, it costs more for no benefit, it simply doesn't perform as well in this application.

 

Designing passive loudspeakers is very simple and doesn't require an electronics engineer, so many companies don't have one and therefore have to buy in active amplifiers. Several competing companies use the same one from a Chinese supplier. It comprises of an A to D convertor in a DSP chip feeding some Class D amps that allows gain control, equalisation, moveable crossover points and an output for a Sub if required. They can make hundreds, all the same and then program them to suit individual customers who can then use the not very USP term "Digital". It's a bit like a few years ago when we had a Vacuum cleaner and a hair dryer with Turbo written on them.

 

Sadly Meridian hadn't been doing very well and have been acquired by Richemont who own the Dunhill brand and with whom they collaborated to produce the Clock Radio/DVD players.

 

ADM9.1s are just a purist audiophile implementation of classic theory, they use the most up to date components, robotic assembly techniques and cost savings are because a multitude of expensive separate enclosures are no longer needed.

 

Ashley

 

 

 

[shenzi]

Another question for Ashley: From your website, do i understand correctly that the AVI Amp-Paks are two amplifiers and an electronic crossover in one box? Are these are specific to AVI speakers?

 

It is a pity about Meridian but they did seem to go from clear, innovative beginnings to a large, do everything, luxury brand.

 

[Ashley James]

Shenzi

 

We make what we call Amp-Paks and these are simply amplifiers that can be attached to the back of our passive two way speakers. They have nothing in common with the Active system in the ADM9.1s that you can read about in the section devoted to them on our website.

 

The major difference between ADM9.1s and other fully active loudspeakers is that they contain a remote controlled three input preamplifier that has two digital and one analogue input. As far as we are aware the others all require a separate preamplifier and DAC, which adds significantly to the overall cost.

 

What many hi fi enthusiasts may not be aware of is that the hi fi industry suffered a severe decline in the UK in the late nineties and it didn't really recover. This fall coincided with a big increase in Multi room and home Cinema installation sales. The early systems were fearfully expensive and more than made up for the loss of hi fi revenue. One dealer explained that hi fi had dropped from 90% of his business to 10%! Dealers were selling very expensive hi fi products on the end of control systems from the likes of AMX and Crestron. However it wasn't very long before this became a very competitive market indeed and that lighting and TV became more important than sound. Not only that but sound was better catered for by Sonos, Squeezebox and Apple and customers could it themselves.

 

The situation now is that the separates market is tiny and declining, companies are losing money and some may not survive. I'm certain that Chris did the right thing in starting this Forum and not surprised that someone like Daphe, who's involved in Venture Capital investment, is on here for this is the future of audio.

 

Ashley

 

 

 

[tfarney]

I'm not Ashley, but I'll give you the fluffy answer: Theoretically, the best solution is for everything to remain zeros and ones until just before voltage is required on the speaker terminals. This removes all chances of analog signal degeneration and noise and makes silver wire, audiophile fuses and capacitors the price of jewels a non-issue.

 

Practically, what is theoretically best may not yet be the best solution.

 

Tim

 

[BEEMB]

I seem to recall somebody posting on this forum was heading to AVI for a listening session ...

 

Wonder how they got on ?

 

 

M.

 

[Labarum]

That is what I was trying to tease out of members.

 

As you say, Tim, the Meridian approach of staying in the digital domain as long as possible is a theoretical best, but engineering is a series of practical and economic compromises.

 

AVIs solution is one such. I am moving towards another, having too much invested in a pair of passive speakers.

 

Yes, in theory, strapping the voice coil to the amp with three inches of copper ought to be the best, but passive speakers well implemented can work really well with good amplification. Goodness, AVI themselves have adopted that approach till very recently.

 

So, I have a good but inexpensive DAC (The Beresford) directly driving a refurbished Quad 405-2. It is presently driven from a PC which is too noisy for the purpose, but I will replace it with a Squeezebox for bit perfect streaming from a PC in the next room. The DAC also takes optical input from my Virgin Media Box for Radio and TV. The 128Kb stream from the Virgin Box is at least as good as my Quad FM Tuner.

 

Now, if AVI were to recast their electronics into a DAC-Preamp box that might be another hybrid product that might sell on today's market, if the price was right.

 

I look forward to seeing AVI market larger digital active speakers, but on the eggs and baskets principal the DAC-Preamp might sell to many with much still invested in traditional HiFi separates. Now if the Squeezebox Transporter were rather cheaper . . . It is over-engineered for my purposes.

 

And I must take up Ash's kind offer of a visit. He knows I won't buy ADM9.1, not because of any philosophical objection (quite the contrary), but because I have chosen another set of acoustic and economic compromises.

 

 

[Ashley James]

Tim

Class D Amplifiers have considerably more noise and distortion in them than Linear Class B, they are about 100 times worse and it's very obvious. They are also more complex, more expensive and potentially less reliable. Mart investigated this all very thoroughly before designing ADM9.1s as he did. We even had visits from the Chipset manufacturers with an engineer, so that we could compare them with the results we were achieving. They sound quite good and better than lots of analogue amplifiers, but a bit "hashy" and gritty.

 

Beemb

 

As no one has come here and not bought, I'd assume that was the outcome.

 

Brian

 

If I knew how to post a graph on this Forum I'd put one up that show how much sensitive your ears are in the crossover region of a passive loudspeaker, it's a huge peak and that make it the last big hurdle in loudspeaker design. Put simply, at it's best an active crossover reduces the noise made by a passive crossover by a factor of at least 100, which is why BEEMB's brother noticed his passive speakers were much brighter. It's the are around the high notes on a violin.

It makes for a less fatiguing listening experience.

 

Ashley

 

[Daphne]

Hi Ashley:

 

As usual, you have brought to light some very interesting points.

 

The electronic entertainment industry is currently unstable; and when any industry in unstable the doors of opportunity are wide open.

 

So what contributes to this current Chaos? To start with, the industry is undergoing a period of the changing of the guard. Many of the technology leaders have, or are currently, approaching their senior years. The innovators of semiconductors, circuit board design, internet communications, all the technology we take for granted on a daily basis. The next generation, who grew up and became adults during the technology boom are the new innovators and entrepreneurs. Currently, the cycle of generations are starting to overlap which creates a gray area. What last swan song will the seniors perform to ensure their legacy? What new frontiers will the next generation open?

 

I'm going to illustrate a few examples in the audio industry. There are many examples, I'm just selecting a few at random. Founding leadership does not last forever. There comes a time when the owner/s realize there is more to life than running the business, especially in their senior years (no one dreams of dropping dead on the job). The company has employees, people who depend on the leadership for their livelihood, employees with wives and children in school, and medical bills, and car payments. The owner/s will need to find a replacement so the company continues. The best solution is to find a competent entrepreneur, highly interested in their business, to buy out their shares and take control. Optional solutions include merging, or selling to a compatible business; or selling out to an equity buyout group. In other words, they have the opportunity to reap the financial benefits of their years of hard work.

 

A major portion of the audio industry is comprised of several hundred small businesses. I have selected two: Martin Logan and Paradigm loudspeaker manufacturers. Both have gone the way of yielding to an equity buyout group, ShoreView Industries. The ShoreView management team is very good at what they do - managing manufacturing businesses. However, these are high end speaker makers selling their finished products to a mid to luxury consumer market. All their other companies make plastic, metal and electronic products for other industries.

 

ShoreView's management mentality is to apply the same principles they do with all their manufacturing companies. Expand the product line, increase sales through current dealers and partners, expand the geographical footprint into the international market, and pursue out sourcing to the max in Asia (meaning cheap parts from China). ShoreView does not purchase businesses in trouble. They are highly intelligent businessmen and like stable businesses with the potential for a good return on investment. However, they are under the impression that high end speakers are like any other industrial product, and their proven management philosophy cannot fail. But remember, businesses purchase goods and services with a logical process, consumers do not, especially in the luxury market. So, what will be the outcome: either ShoreView will learn a good lesson and adapt, or look to unload the speaker companies.

 

In contrast, Meridian is preparing for the future now. They have a more substantial position in the audio visual market than the speaker companies described above. The founders have a separate entity stocked with intellectual property (joint patents with Dolby Laboratories). For a brief time back in the late 1980s Meridian was partnered with KEF, but by 1992 had purchased back their shares and have since been funded by the Taylor family. Recently, they formed a partnership with Muse SA, a group on investors from the entertainment industry who brought in the luxury marketing group of Johann Rupert (owner of Richemont who is dedicated to the luxury markets of diamonds, pearls, diamonds, precious gems, diamonds, Swiss watches, and fountain pens. Dunhill was a mercy purchase for Rupert, they are lucky to still be in business.) Muse SA only owns a portion of Meridian, but can secure a more substantial position in the international luxury market. A good move for Meridian to establish a gateway to expand sales of their expensive high end audio visual products.

 

The interesting factor in aging A/V companies are the equity buyout groups who specialize only in like companies such as D&M Holdings (Denon, Marantz, McIntosh, Boston, Snell, Escient, Calrec, Allen&Heath, Denon DJ). Top management here are the Japanese, and they are very savvy. All the companies combine their purchasing power and share technology which gives them a definite edge in multiple markets. However, other groups like the idiots at Harmon International Industries (Mark Levinson, Lexicon, Revel, JBL, Infinity, Harmon Kardon, etc.), are only doing moderately at present. Actually their products have a strong standing in the marketplace. Their current lack of success is partly due to poor executive level decisions.

 

So, with a sudden downturn in the global economy, the older generation selling out, companies outsourcing for the most inexpensive parts, lack of sales in the auto industry (less car audio sales, new and aftermarket), management with little or no experience in the A/V industry making bizarre decisions, and now the real clincher - emerging computer home entertainment. The trends are not shining a favorable light on the audio industry.

 

High End audio is in trouble, sales are only stable in the geographical haunts of the rich and famous. Frivolous audio equipment reviews now appear in luxury lifestyle magazines next to diamond encrusted watches, designer sunglasses, Spas, Bentleys, and Ferraries.

 

Mid fi sales have been down for the past several years, especially for the large corps like Sony and Panasonic who are only pleased with the car audio market.

 

Consumers have already taken notice of computer entertainment. We use our computers extensively for business, social communication, shopping, sex thrills, and the retrieval of knowledge. Now that same little box can not only offer addictive games, but quality audio and video for a very reasonable cost. The population under 25 years of age will embrace it first because computers are integral with their lifestyle. A DAC card, solid state memory, and great self powered speakers is the wave of the future. All assembled for less than a mid fi system with the sound quality of high end, and all music and video selections can be easily downloaded.

 

With so many doors of opportunity open there are multitudes of hidden agendas consumers are unaware of. But the mass consumer market will determine the direction and outcome. Predictions in the Audio Visual market, like many markets, are very difficult to make because consumers do not purchase rationally, but emotionally. What will capture the market? Will it be a separate do all entertainment server controlled by one's current and/or future home computer? Will the computer companies integrate the A/V systems in one computer box? Will servers attached to new innovative internet services win out? Just too early for even a basic prediction. But the new wave is here, and in my opinion, I don't see these features disappearing.

 

The subject of this discussion is audio reviews. We all have our opinions on what has been written in the past. I wonder what the same writers will have to say in the future (from whatever audio magazines still in business).

 

[ Difficult to write about computers when one is only accustomed to word processing. Oh the reference system will have changed: it will most likely be a PC, few authors use a Mac. The Sony Sonic Storm desktop running Windows Universe Pro Edition operating system, an Intel 12 core, 8MHz chip, with the author's $9500 Krell X15 Audio Barrier reference sound and DAC board, 32" HDTV monitor, and 10" touch screen remote. The speakers in review are connected to his reference Nordost cables running through shielded carbon fiber conduit. He selects a 24/192 file on the re-re-re-mastered, master file of Pink Floyd Dark side of the Moon. Then we will receive the same old language used for the past 20 years. ]

 

Could we see reviews traditional to the computer industry? 12 DAC boards lined up, internal and external, tested and rated, just like all other cards.

 

daphne

 

 

 

 

 

[tfarney]

"If I knew how to post a graph on this Forum I'd put one up that show how much sensitive your ears are in the crossover region of a passive loudspeaker..."

 

As they say in the evangelical churches of north America, "I want to testify."

 

I am a dedicated, obsessive, compulsive, out-of-control headphone listener. What that means is that I am willing to let slide the obvious virtues of speaker imaging that effectively imitates a real performance venue for the midrange purity that comes from listening to an appropriately driven set of truly full-range single drivers with no crossovers -- passive, active, or otherwise -- in the way of the pure unadulterated beauty, transparency and coherence of Shelby Lynne's voice, Miles Davis' trumpet or Jerry Douglas' dobro. I can hear the distortions caused by crossovers, passive and active, and those caused by multiple drivers attempting to reproduce the same frequencies with drivers of different sizes, properties, and locations on the plank that forms the front of the speaker.

 

These things disturb me. Much more than the comparatively insignificant differences between DACs and quality amplifiers that y'all (actually, the true Southern plural of that would be 'all y'all) spend so much money on.

 

It's a burden. It's a quest. It's a heavy, heavy cross to bear.

 

 

Tim

 

[audiozorro]

Daphne, thank you for your insight and thought provoking ideas. Except for your discussion on business owners much of what you say focuses on the industry or a top down business point of view. I prefer to take the bottom up point of view and focus on what the consumer wants.

 

Take for instance the issue of copy protection. Industry wants it, consumers hate it. I just had a frustrating experience this week when one of my DVD-R failed to play properly in my Sony DVD Recorder/Player. It was a Turner Classic Movie, Enchantment, starring David Niven and Teresa Wright, which I recorded off Tivo several months ago. It used to play alright, but this time halfway thru the movie the Sony player just stop reading the disc. I cursed Sony and tried another DVD player to no avail. This does not seem to be an isolated incident. I recorded several Star Trek episodes from Tivo to create 6 hours DVDs. The other day I tried playing two different discs, and in each case the player would only play the first 2 one-hour episodes. I have other recorded DVDs where I have to get past the beginning track to play the entire disc or I get TOC read errors.

 

There could be many reasons that may be responsible for these problems but I strongly suspect it is copy protection schemes and the complexity it entails at the heart of these problems. I never had such problems with VCRs and video tapes. And of course the commercial DVDs play just fine in all my equipment.

 

I can’t say enough how pleased I am with the reliability of LPs, AIFF files and, when I don’t care much about sound quality, MP3 files. I’ve never had any problems with my audio CDs, but the first Blu-ray disc I bought, The Legends of Jazz, failed to read because the publisher authored the disc incorrectly. And as much as I sometimes like the sonic qualities of two channel and multi-channel SACDs, I am adverse to proprietary formats, especially those likely to disappear. It’s always interesting to reflect on various audio formats over the years and speculate what may survive across generations.

 

Anyway, I agree that high end audio is in trouble but it has always been a niche market. The larger home theater market will thrive though it will obviously be slowed by the worsening economy. Similarly, the computer market will continue but will be slowed by the economy. But what will be the next product to dominate the consumer market? Each time after the personal computer, VCR, DVD player, cell phone or iPod, something else always seems to come along.

 

 

[Labarum]

Thank you, Daphne, for your analysis. It had not occurred to me the present situation arises out of generational paradigm shifts - the elderly copy owners wanting to stay in their comfort zone but the young consumers finding new and better solutions using technology that makes their elders uncomfortable.

 

And I am convinced, Ashley, that AVI has it right: as I have said to you before, the only contribution trad HiFi manufacturers can make in the long term is domestically friendly active loudspeakers - the rest can be managed in hardwares and softwares supplied elsewhere.

 

Managing the transition will make or break many companies.

 

[tfarney]

"Managing the transition will make or break many companies."

 

It always does.

 

Tim

 

[Ashley James]

Tim

 

You're right to back Yamaha, they are the largest manufacturer in the world of Very Large Scale Integrated Chips (VSLIs), they are world leaders in audio engineering on the pro side and they make what the market is interested in and can afford for the consumer market. They do it all to an exceptional standard, just as they do with Motorbikes, Musical Instruments including their pianos. There isn't a hi end audio that could come close to the engineering integrity or innovative skills of Yamaha. They could blow their Trumpet much harder and not be exaggerating.

 

I put things very poorly Tim, so please assume that I agree with Chris and know that you are someone I'd like to count as a friend. However a DAC comprises of a bit of digital and a bit of analogue, the digital bit of which is operating at radio frequencies and therefore transmitting. If you measure the analogue output of a certain streaming device (there are lots like this) when it's not playing , you'll see a few millivolts of radio frequency hash, which ought not to be there and which will react differently depending on whose power amp it is connected to. Some will sound OK and others dreadful. It wouldn't be if there if the designer had followed the instructions the chipset manufacturer had given him.

 

I fancy you've been around long enough to remember the hysteria from certain amplifier manufacturers when CD players first appeared. They did everything they could to discredit it, despite the fact that it sounded a hell of a lot better with some amplifiers (not theirs of course) than did LP. These days the problems are resolved and hash on the outputs of DAC is avoidable, if not by all.

 

Therefore and as Analogue Amplifiers are still better than digital ones and that's what we use and it works well because our DAC has nothing on its output that shouldn't be there .

 

Daphne

 

I'm 62 and still loving every new piece of technology that comes along, in the scheme of things, ADM9.1s are technological minnows, but they've shoved us into the limelight, they've demonstrated that it's what the market is looking for and I don't count it the least bit surprising that it was an engineering team from Yamaha who spent more time looking at them than anyone else at the Bristol Hi fi show. They saw the future.

 

As for acquiring companies in good condition and building on their strengths, it may happen, but not in my experience. For years I spent time assisting people buying and trying to buy them to do just that. What I found was a fanatic at the centre who'd had a good idea and a degree of success and who lived out his life through the experiences his company had given him. He didn't have any management skills because they weren't needed, his product sold well till others caught up, which was usually why we got a look at it. The trouble is that this success had shot him into the limelight, had made him famous and given him a life very different to the boring one he'd had before. Having made money he'd spent it making things he fancied, but of no interest to the market and now he got into a financial mess and was prepared to offer a minority share holding in a private company as well as a "directorship" to someone who'd finance his continuing 'cock ups'. Suckers often fell for this one and millions have been wasted over the last 15 years in trying to resuscitate audio companies.

 

The truth is that extracting these people from their companies is often essential if they are to survive and grow because they need to be run in a professional manner. I well remember the expressions on some of these people's faces as they came to the realisation that this was the end. This story is a generalisation, but common in the processing of acquiring small companies that have potential in the right hands.

 

I make no pretence of understanding the hi end market at all, but can see no reason why very wealthy people should be any more attracted to expensive audio only equipment than any other group.

 

Ashley

 

 

 

 

 

[Labarum]

Somewhere, in this discussion Ashley, you say some/many/most makers of active speakers buy in programmable electronics from the far east, which, you say, is less than ideal for purpose.

 

1. Apart from yourselves and the little Quads I can only think of two manufacturers that make Domestic Actives: Meridian (digital input) and ATC (analogue input). Who are the others?

 

2. If, as with your product, the crossover is in the analogue domain, there is no particular technical reason why the DAC and Pre-amp functions should not be in a separate box. Flexibility is increased in a fast developing technology - the analogue actives are likely the age less fast than the DAC. You rightly point out that there are cost savings in the one box solution - the cost of the DAC-Pre case is avoided. I wonder how important the "eggs all in one basket" argument is. Have you considered marketing a DAC-Preamp?

 

[GazD]

Nice post Daphne.

 

The scenario you describe is very familiar to me.

The company I work for specialises in a certain area of the metal industry and number of years ago were bought by a very large USA company.

 

Luckily for us they were quick to realise that our business model was different to theirs. We have just had a number of very good years and now were are prepared to face the inevitable downturn we will see in our industry.

 

The next generation has alway been affecting businesses on various levels. We had alway felt that having an expat in charge of our overseas operations was the wisest choice. With the current generation of locals coming through with much broader experiences and usually having studied abroad this is changing. (not to mention the obvious cost savings)

 

I honestly hope that 'high end' audio (and my definition of this is just good sounding equipment) will never die, but I certainly believe the the way in which it is delivered to our homes is already changing.

 

 

[tfarney]

"I put things very poorly Tim, so please assume that I agree with Chris and know that you are someone I'd like to count as a friend. However a DAC comprises of a bit of digital and a bit of analogue, the digital bit of which is operating at radio frequencies and therefore transmitting. If you measure the analogue output of a certain streaming device (there are lots like this) when it's not playing , you'll see a few millivolts of radio frequency hash, which ought not to be there and which will react differently depending on whose power amp it is connected to. Some will sound OK and others dreadful. It wouldn't be if there if the designer had followed the instructions the chipset manufacturer had given him."

 

Ashley, you put things just fine. I'm not sure I understand what you're driving at here, though -- that there is a potential for the introduction of noise in the digital processing going on inside a DAC, but that can easily be mitigated by simply following the instructions of the chip manufacturer in the DACs design? And that the noise in question can be made much better or worse, depending on the design of the amp it is connected to?

 

If I've got that about right, given that the technology has been around a couple of decades and is pretty mature at this point, is it safe to assume that most DACs will not have these problems with most amps?

 

Might it also be safe to assume that, given reasonably responsible design, that these problems would almost never exist when amp and DAC are in one piece, like the A/V receiver, where they are meant to work together?

 

Am I assuming too much? Really, I'm just trying to figure out why it is that the audiophile community raves over and argues over DACs, when I can only very rarely hear them at all. It's not that my ears are bad. I can hear bad mixing and/or mastering. I can certainly hear the differences between speakers. I can hear a load under powered. But the sonic differences between well-designed electronic components seem to me to be insignificant.

 

Tim

 

[Ashley James]

Brian

 

I don't think there is any part of an active speaker like ADM9.1s that is likely to last less well than the rest and I'm certain that the package will last much longer than expensive separates. ATCs manage that they last for ever running alarmingly hot by our standards.

 

There a substantial number of different Active speakers available on the pro side and some of which are close relatives of hi fi offerings from the same companies. I obviously shan't mention which ones use electronics from the same Chinese factory but here's a list; Dynaudio, Tannoy, Genelec, Focal, possibly even Spendor and Harbeth, certainly Mackie, Yamaha, Adam, Genelec, JBL and also from well known German company who I think are called Backus an Muller and many more. These are all at least competitors for separates costing a couple of three times the price and I know from calls received at AVI that many people are already using them with their computers. It's well worth reading Sound On Sound online if you're interested, it's an excellent publication and one of the most influential in the world.

 

As for splitting up the electronics in the ADM9.1s, it isn't really practical because they really are a fully integrated "synergistic" system. Furthermore I don't think we could easily sell a DAC/preamp through hi fi retailers who are "resistant" to the concept of our speakers. We're very grateful for the direct sales we make to people who are as reluctant to visit the shops as they are to sell "computer speakers".

 

I'd wholeheartedly recommend Cambridge Audio to anyone in the UK who's looking for cost effective separates although I'm sure Nad and Rotel are as good. If you're interested in more expensive options, then it's prudent to make sure they are better than the aforementioned.

 

Ashley

 

[tino]

Hi again Ashley,

As a reminder, I am beembs brother.

I saw that you just mentioned Mackie (along with others) and thought I'd mention that I bought a pair of their Active HR624 monitors this week. I am extremely happy with them, and would recommend them to anyone looking to "go active". Of course they do not have an onboard dac or preamp like the ADM 9.1s, so are not quite as practical, but then they cost less. They have quite amazing bass extension and control, and are also a step up from my old Proac's in the mid and treble department too. Soundonsound speak very highly of them. Looking at the Pro audio market has opened up a whole new world........

Martin

 

 

[BEEMB]

 

Martin - great ... now get the Mac or PC setup ... ;-)

 

[tino]

A Mac will come eventually................any donations welcome !!

 

[nathan0001]

Hi,

I know I have touched on this issue before, but I'm still struggling after a lot of reading to get my head round something, and whilst this post is on the subject of ADM 9.1 analogue performance I'd like to go back to the amps ! I have no doubt they are very powerful, and more than powerful enough to control their own drivers, but, for example, they have power output figures higher than most Krell amps!

Ashley said to me once, "power is simply volts multiplied by current". The only way I can see that being the case in relation to amplifier power output is if the figure being quoted is the peak power output or "pmpo". Otherwise that is not true, as many manufacturers quote with different distortion levels, different resistance levels and continuous power output.

I assume the 250 / 75 watts are into the load presented by the ADM's drive units and not the standard 8 ohms most amp manufactures quote (this giving a lower figure).

To summarise, I guess I just want to know:

Are the quoted figures continuous or peak?

What resistance are they measured into?

What is the distortion at these max power levels ?

 

If anyone else knows a little more about power outputs and how they are measured, I'd like know !!

Nathan

 

[Labarum]

Yes Ashley, come clean.

 

Each box must have a pretty hefty transformer in it if that power is available.

 

That question has been in my mind for a bit.

 

[Ashley James]

Nathan

 

As I've already stated. the power outputs are 250 and 75 watts RMS per channel and believe it or not the distortion figure at that level in the mid band os probably be as low 0.0001% THD + Noise. In other words exceptionally low by any standards. What is even more important is the distortion figures are just as good at low levels where most of the energy in music is. In fact music comprises of a continuous requirement of a fraction of a Watt with constant instantaneous peaks that may run into hundreds. Therefore you can never achieve the RMS power output anyway. Peak power is probably more important, so we could actually double the RMS figure as a guide.

 

Transistors have to operate in their Safe Operating Area or they blow up. Therefore anyone making a stand alone power amplifier has to design it so that it can handle the worst impedance it it likely to see and given the competence of some passive speakers designers, this can be very low indeed. The alternative is to provide some form of protection at higher impedance with its inevitable affect on the sound quality. Krell being a serious hi end product is likely to be able to cope with anything, at a price. And therein lies the enormous benefit of active speakers, because the load is known and easy, large amounts of current are unnecessary, so we can design a much less expensive amplifier with more than enough headroom and lower distortion than a stand alone one. As you halve the impedance an amplifier sees, so you ask it to produce twice the power and that is accompanied by twice the distortion.

 

Having explained all this again I feel compelled to ask why this particular aspect of the design of has so pre-occupied you, especially as you don't have to look very far to discover that ADM9.1s are considerably louder than conventional passive speakers of a similar size and with far less distortion. The power has to be coming from somewhere.

 

I promise you that they are truthfully described.

 

Ashley

 

[radar2886]

Nathan

I do not know how the output is measured but as a 9.1 owner I can say the amps have plenty of power to drive the speakers. I do not know why people continue to question how the amps are measured. In my experience power output from AVI has never been a problem. Their integrated and stereo amp had some of the best control over speakers that I have ever heard regardless of the speaker. All I can say about the 9.1s is that they play plenty loud and clean in my 36' by 30' basement. In fact my neighbors and my ears give out long before the 9.1s.