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Mark Paddick
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Friday, November 24, 2006 - 10:46 am, by:  Mark Paddick (Sparks) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

I got an email asking some pertinent questions about a stereo upgrade and whether the speakers should be replaced.
Here's the reply;

Power ratings are hard to estimate. Not because it's a hard thing to do but because no two manufacturers use the same methods. This is all advertising bullshit and gimmickry.
The Soarer speakers are rated somewhere around 30 to 40 real watts i.e. watts RMS or continuous sine wave power. This is the only really meaningful way to rate speakers or amps.
Manufacturers use all sorts of tricks to make their stuff appear better. Music power is a common one. Basically it is about double the RMS power.
Peak music power (PMPO) is about double to treble that again
There are probably more and just as many sneaky tricks used while testing to gain good figures.
So the stock Soarer speakers are 30W RMS, or 60 to 80 W peak or anything up to 800 advertising Watts. They are rated at 4 ohms impedance.
Makes it hard to match up stuff.
You won't have any trouble with that amp. The factory speakers are much better than they look. The one addition I would make is to fit a good crossover between the front bass and treble speakers. (Jaycar CX-2612 is perfect; take no notice of the fact that it is intended for an 8 ohm system. I have done the maths, it will suit and I use them myself). The amp will probably be capable of blowing the cones clean off the speakers if you get carried away but you will hear the speakers start to distort as you wind the power up. I have seen people do that kind of stuff and cannot understand how they kept going when you can hear the thing complaining. They will probably take a lot more than expected.
One reason is that decent speaker ratings are given "unloaded" so that 30 Watts or so is in open air with no baffling. Once the speaker is enclosed in a box or fitted to a rear shelf those numbers will increase markedly. And the Soarer door enclosures are well designed specifically for those speakers so the max power when fitted is probably double or more.

If replacing the speakers then it is a different story again. A lot will depend upon the amplifier setup. IC output amps like the factory ones have a rising distortion characteristic with falling speaker impedance. This is a non-linear thing too so halving the speaker impedance increases the amplifier distortion by four to 50 times; it also increases power output.
Years ago high power from an amp was not easy to achieve and it became the 'norm' to use 4 ohm speakers in car audio mainly for this reason i.e. higher power was obtainable from the same amp into a 4 ohm load rather than the more normal 8 ohm load used for domestic HiFi.
Nowadays high power amp technology is common and amplifier power is not at the premium that it was. Therefore there is no longer the need for low impedance speakers but no one seems to have noticed.
It makes much more sense now to use 8 ohm speakers because the amplifier distortion levels can be as much as 16 times lower using them. All amplifiers exhibit this trait to a certain extent but IC output stages are worse by far.. Most high power stuff has discreet ouptut stage technology BUT the pre-amp and drver stages are often IC power amps so the amplifier overall will still exhibit this rising distortion trait.
This means that the factory amps can be looked at as about 30 Watts RMS into 8 ohms and driven this way the peak amplifier distortion is 1/24th of what it is into 4 ohms.. This is damn near the perfect number for power out. Many top quality HiFi 8 ohm drivers are rated at around 30 WRMS. KEF B110's for one and even the mighty B139 is only rated at 30WRMS (yes, the same speakers I have at home in transmission lines being driven with 800WRMS from an old Bose theatre amp).
Although 30 W is really a bit low (the speakers will take more when properly loaded and the amp distortion will be highest at max output so the amp should be nearer 50 or 60 Watts but we have 30 so we'll go with that) the results really are quite amazing with good 8 ohm drivers. This is cheap high quality sound.
This is exactly the setup I run in my green car with only the Sub amp replaced with a Jaycar one and the Jaycar sub .... the KEF B139 is coming though.
I have now switched to the US spec Nakamichi system amplifier which is rated at 40WRMS/channel plus a 100WRMS sub amp and these are very conservative ratings. Two of these give 8 channels which are split into 6 front and two rear with the two 100W sub amps each driving a voice coil of the Jaycar sub. An alpine active crossover unit runs the show and is fed from the factory EMV stereo (with mods).
The US amps are great for fitting as they fit to the standard amp brackets and by removing the Sat/Nav and fitting TT brackets a second factory amp can be fitted on factory brackets with factory trim and no mods at all. This gets around the biggest pain with Soarers; having to fit the amps somewhere.
The only downside is that the Yanks know how good these amps are too, they are relatively rare also. So you will pay upwards of US$300 to $400 for one.
Scott Ferguson
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Saturday, November 25, 2006 - 02:33 am, by:  Scott Ferguson (Scott_ferguson) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

I finally asked a pertinent question!
Blaine Hanson
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Monday, November 27, 2006 - 07:58 am, by:  Blaine Hanson (Blaine) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Mark, thank you for taking the time and effort to write such a detailed informative article. I found it very interesting.
Mark Paddick
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Monday, November 27, 2006 - 08:23 am, by:  Mark Paddick (Sparks) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

I just had an amp to look at.
It is a very expensive US 5 channel amp (actually made in China and cheap crap).
It has "Dicreet Mosfet Technology" and "1500Watts total power" printed in very large letters all over it and is apparently a "Limited Edition" whatever that means.
It has a nice alloy case very nicely screen-printed in a mass-produced sort of way.

It does have discreet Mosfets. In the switch mode power supply (which is a good place for them).
The actual amps are IC output devices, which are in fact quite good but do have all the failings of the breed. There are six of these. Optimistic output ratings are about 80WRMS each with the two in bridge mode capable of maybe 200. This is a total of (4 x 80)+ 200 which I make to be 520 Watts absolute maximum with about 10 to 15% distortion. More like 350 Watts at a reasonable distortion level.
How this ever got to be "Dicreet Mosfet technology" and "1500 Watts total" is beyond me!

Thank God it's a "Limited Edition". There may not be too many more of them around.

Oh, and the fault was that the discreet mosfets had seen a bit of an overlaod and vapourised, not very dicreetly at all, taking a fair portion of the circuit board with them....unfixable.
Mark Paddick
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Monday, November 27, 2006 - 08:27 am, by:  Mark Paddick (Sparks) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Needless to say, I replaced the amp with a Jaycar one which is, in the owners' opinion, about 10 times better than the old one...
...and took great pleasure in leaving the old one in the local Bus stop and seeing it flattened by a 216 Bus.
Damian Ware
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Tuesday, November 28, 2006 - 07:00 pm, by:  Damian Ware (Frozenpod) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

So true Mark.

I built a real 500W amplifier last year. I got the THD down to 0.38% which was not hearable by most people but I could still hear it.

Let me tell you right now the 50W is dam loud, playing in a large living room, 6.5 X 5 with high roof line output only 50 real watts (no where near the capabilities of the amp) was more than enough power. It was louder than a good quality commercially produced amp I have at home that was supposedly 200WRMS. It was similar output power to a audiophile amp of my dad's that has doesn't exactly have a rating. They don't advertise how much power it produces or the THD level but they say it is produces more dB in the same room with the same setup that has a rated 150WRMS.

I did a comparison with it against a mates 500W car sub amp and to put it simply there was none.

After much testing at a distorted but somewhat bearable (only for about 10seconds before you feel the need to smash things) level it was similar to my amp that was producing a real 100W. I didn't have a dB meter on me but from passed experience this would be close to the 115dB mark.

Good amp doesn't always be expensive and the power figures are meaningless. What you want is quality.

I had a 7k system in a previous car that only produced 114dB and yes that was more than loud enough. But the expense went into quality, it was one of the nicest sounding audio systems I have listened to. I was only running a very expensive quality 45WRMS amp and I was producing close to my brothers car which was running a 220WRMS amp.


Mark just a question for you about the Jaycar amps, my understanding was the first version wasn't very good at all but the latest is really really good.

I believe it has also one some competitions for best overall value power and sound quality is that correct.


I am strongly considering continuing with the design to produce a sellable product but given the market place I don't think it is worth the effort.

99.9% of people seem to only want a big power figure and they go to JB-HI and walk about 400 bucks lighter with a hunk of that they have been told is great and they believe it has the 400 or 500WRMS written on it. They also cant tell the difference between a good amp and one that sounds house.

If I can gain enough interest I might complete the design, I would like to make a slight tweak and all that really remains is the power supply and casing. At the moment I have too many project and not enough time.
Mark Paddick
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Wednesday, November 29, 2006 - 07:57 am, by:  Mark Paddick (Sparks) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Power is not always the answer and if it is it was probably the wrong question!

I get a LOT of comments about the system in my green car now.
It does sound good but it's not one of those that you can stand 50 feet away from the car to listen to. It sounds best in the car which is exactly where I want it to. the only real power is the sub and Jaycar amp.

The first series old blue Jaycar amps were average. They weren't quite crap but not far from it.
The newer black and then silver amps are among the best made anywhere at any price. Especially the 2 x 150. The 4 x100 analogue, and now the new digital series, are very good but use the same power supply as the 150. The 150 is overpowersupplied (new word!) which is one of the reasons it is so good. In the 4 x 100 that same power supply is adequate but not great. Very heavy 12v input wiring helps a lot here.
I can't mention any names but if you look hard enough you will find a slightly older model (year or two) imported American, high end amp in the US$1200 region that the top and bottom panels from the black Jaycar amp will fit perfectly. 'Cos they came from the same factory at the same time!!!
These American amps are hard to find now because they really can't sell them against the Jaycar ones at ten times the price. (how the Yank version gets to be "American made" I don't know. Maybe the top and bottom panels were made in the US of A, but the rest comes from China. And there ain't nothing wrong with that. The Chinese can do good stuff, especially if you specify exactly what you want and how you want it).

The Jaycar amps and subs have won several competitions and awards and are favourites of at least one motoring/audio magazine.
For the money they are unbeatable and their specs are good enough for real quality stereo if used intelligently. I can't be bothered building car amps anymore, and the Jaycar amps are partly responsible for that but I still do my home stereo amps myself.
My old home amp was a 16 channel setup (4 way active crossover WITH real time active correctional feedback and digital equalisation).
The individual amps are 30 Watt Bailey amps (Wireless World 1968 !!!). These are one of the best transistorised amps ever designed. Distortion and linearity figures are phenomenal but only 30 Watts.
Mind you the heat sinks are big enough for 600W/chann and the power supply is rated at a conservative 2kW. The amps do produce a continuous class A 30 Watts square wave for 6 hours straight without getting more than warm and distortion is below 0.001% i.e. that is the resolution of the test gear used and it registers nothing at all.
I have measured what would be a 900W peak out of this setup, with no measurable distortion.

I have thought about digital equalisation in the car. That would be the next big step I think. Amps, speakers and the rest are up to real quality now, the only real improvement is going to be in linearity (especially of frequency response) and phase correction to account for compromised speaker locations. Definitely going to multiple amps and active crossover is the step before that but I've already done that.
Using 8 ohm speakers and (US)factory amps the distortion levels are so low that I don't think any useful gains can be had with improved amp design at this stage until the rest of the system catches up.
Damian Ware
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Wednesday, November 29, 2006 - 08:45 am, by:  Damian Ware (Frozenpod) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Yep power isn't the key, quality is. If you get a good amp even if it is a little down on power really good quality speakers which are typically higher efficiency tend to finish off a great system.

As for your car I can say from passed experience even with a really good quality system running test tones and sound meters will give some surprisingly results. Cars are a bit funny in there acoustics, particularly in comparison to a rectangular room.

For some reason with my system in the camry I had a peak at 88Hz in mine from the rear speakers (not the sub) and a small dip at 120Hz.

Everywhere else in the range from about 30Hz to 20Hz it was almost perfectly flat.
Michael Marchant
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Wednesday, November 29, 2006 - 02:53 pm, by:  Michael Marchant (Mavric) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)


Damian Ware wrote on Wednesday, November 29, 2006 - 08:45 am:

really good quality speakers which are typically higher efficiency



Where did you get that from?
Mark Paddick
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Wednesday, November 29, 2006 - 03:30 pm, by:  Mark Paddick (Sparks) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Depends what you are talking about. In current car audio trends the use of highly inefficient speakers driven by huge amps is common. Nothing wrong with that either. It allows you to really attack the speaker damping to sort out its' shortcomings. By heavily damping all the peaks and building the thing to handle some power you end up with a speaker with a very flat response compared to other designs. It can have low distortion too but as I've pointed out before most amps, if not all, work best into higher loads and most car audio speakers are low impedance so the amp distortion will be much higher.
You can also try to compensate to some degree for the average car environment and this can work well too.
It can work very well but is wasteful of power.

Domestic HiFi on the other hand often uses a different approach altogether. Using highly efficient naturally accurate drivers and building the enclosure to do the damping. This style of driver is always a very good one and efficient.

Both approaches, and others, have their merits and none are perfect. Some excel in different areas. All are very good if done properly and some combinations are even better than their separate parts.
Damian Ware
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Wednesday, November 29, 2006 - 04:57 pm, by:  Damian Ware (Frozenpod) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)


Michael Marchant wrote on Wednesday, November 29, 2006 - 02:53 pm:

Where did you get that from?




There are always exceptions, ie PA speakers extremely high efficiency with extremely poor sound quality.

My current driver of choice is Focal, they are exceptionally good one of the best in the world if not the best, they typically have an efficiency of 93 to 96dB where as most other drivers are around the 87 to 92dB. But as I said there are exceptions.

As you know every increase in efficiency of 3dB means you can run an amplifier with half the power to produce the same sound level.

My aim with my camry was a HiFi system that would the sound the same as my home system, I got close with as you say naturally accurate drivers.

There are many drivers which while clear are overally bright which sound good for about 10 minutes then get harsh on the ears. They also give the impression of being more powerful even though the sound level when measured in dB is actually less. My brother went down this path by putting in the Focal Kevlars, they are one of the better types like this but after 30 minutes I couldnt wait to get out, where as with my system running the Utopia speakers it was very natural and I would still be very happy listening for hrs and hrs at a time.


All I am going to add at this point it is good to discuss things with someone that actually has a clue what they are talking about. A lot of people simply don't have a clue when it comes to audio and there answer to everything is a crap brand name amp with more power on the label.

Mark don't take this the wrong way but I do disagree about the speaker impedence, with older Class A amps yes it was an issue but with modern transistors and MOSFETS this is no longer the case. (The principle is sound but a tuned human ear can only detect about 0.2% THD) Driving a pure 8 ohm load with no inductance or capacitance is ideal and will always produce the best results, but in the real world speakers coils are far from perfect.

With the lower output impedence you wont notice the difference on a good amp (at least the ones which I have been using) between 8 ohm and 4 ohm speakers. My sub amp is 1 ohm stable, I have run it on a 2ohm load without issue in a mates car that produced 133dB at a sound contest. Sound quality was still good but that wasn't really a concern given the application.
Mark Paddick
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Wednesday, November 29, 2006 - 06:38 pm, by:  Mark Paddick (Sparks) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Rising distortion with decreasing impedance is a trait common to every amplifier design ever even thought of. Class A amps are the best as are any transformer output coupled (valve) amps in this regard but not necessarily any other aspects.
IC amps are particularly bad and are often used in intermediate power stages of large amps. Distortion levels in this sort of amp can be in the 0.5% and above region at low impedance loads, 0.002% at 8 ohm and 0.0005% at 16. These are figures taken directly from manufacturers specs for one of the better more costly IC amps.
There are plenty of high quality IC OP amps that have incredibly low figures but none have any decent power output. great for signal processing and often used there but useless in power driver stages.
This is generally of no concern with sub amp as the ear does not perceive even large amounts of distortion at bass and sub-bass frequencies very well at all. This is why all sorts of liberties can be taken once you decide to go a separate sub. Power is really all you need as you can't hear the distortion (within limits).
As the frequency rises it becomes more important which is why many systems will use a Class A amp for mid and/or tweeters but Class AB or B for bass. Partly this is also due to the fact that Class A has no crossover distortion either but the lower intermodulation and impedance effects contribute to the choice too.

The impedance characteristics of ALL speakers are complex to say the least but almost every design exhibits a peak at the resonant frequency and falling impedance with falling frequency which only makes matters worse. Some like electrostatics throw in a large capacitive effect as well and that makes amp design tricky!
This is why many designs do not include the resonant frequency in the band to be covered by that driver; it avoids the problems at and below the resonant frequency.
This is less true in bass and sub-bass designs as it is deemed inaudible and the only way to get decent bass from some drivers is to operate them at or below resonance. Bass Reflex and some transmission lines are good examples with the enclosure encouraging output below resonance to increase the range. Many closed box designs operate well below resonance and use the falling impedance/higher amp output characteristic to extend bass response.
The average impedance of an average 8 ohm speaker (is there such a thing?) is something like 5 or 6 ohms and can be as low as 3. 4 ohm speakers can be as low as 1.5 ohms at certain frequencies. That's a reason why 2 ohm stable amps are rare and 1 ohm are always a good amp if they're also accounting for that variation in load impedance which some do. In fact some amps are stable into a direct short which they need to be in order to drive a 1 ohm load.
Either way distortion levels will be an order of magnitude lower at double the impedance which is never a bad thing.

The new age of Digital amps changes the whole scene completely...again. distortion and frequency response are dependent on entirely different factors and load impedance is way down the list.
Damian Ware
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Wednesday, November 29, 2006 - 07:45 pm, by:  Damian Ware (Frozenpod) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Mark you are old school with the best of them mate,

I spent the first 3 years of uni deciding whether I should become an audio engineer to have the course removed when I got to it.

As I said modern day amps load impedence doesn't matter.

If you believe manufactures specifications of anything below .1% THD I think you are in for a supprise. I tested countless amplifiers when I built mine on a system that was calibrated to be accurate to 0.002% THD. I found zero amplifiers that produced the specified results.

For example one of my personal amps (this was a cheapy, the first one I ever bought) has a specified 0.01% THD, the results were 0.1% THD at very low power and at 50W real power it was 0.8% THD. At no point did it ever achieve the manufactures specifications.

I discussed the results in depth with the resident audio engineer with 35 years experience and he said that they are achieved in test labs where every component is matched. Resistance tolerances are accounted for and tweaked during test and every silicon device is hand picked and matched. They run the system for a minimum of 4 days as that is how long it takes for the chemicals to settle in semiconductors. Then using equipment that gives them the measurement they want they achieve amazing results. They also used the trick of driving a pure resistance that was of very high impedence instead of the nominal 8 ohms.

He used to work for a big brand name manufacture that will remain nameless had he said this used to happen all the time and the specifications where nearly worthless.

What I found interesting at the time was the best sounding amp of the lot, a 30k valve amp that he bought in from home had the heighest THD of the lot.

It was one of the cleanest smoothest amps I have heard other than what I have at home. Yet the THD was very high 2 to 3% depending on the power output. My entier mindset on audio changed forever on that day.

To put it simple we couldn't pic the difference between his and mine yet the THD figures didn't match at all, neither did the price.

I could talk for hrs about this but I have to get some work done.

Perhaps we can pick this up another time.
Michael Marchant
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Wednesday, November 29, 2006 - 09:24 pm, by:  Michael Marchant (Mavric) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)


Damian Ware wrote on Wednesday, November 29, 2006 - 04:57 pm:

There are always exceptions, ie PA speakers extremely high efficiency with extremely poor sound quality.



I agree that PA speakers SQ is much lower than conventional loudspeakers and they have high sensitivity but they are designed that way to reach very high SPL in large areas, SQ is NOT the number one concern. You really can't compare them to domestic or even car audio drivers/speakers.


Damian Ware wrote on Wednesday, November 29, 2006 - 04:57 pm:


My current driver of choice is Focal, they are exceptionally good one of the best in the world if not the best, they typically have an efficiency of 93 to 96dB where as most other drivers are around the 87 to 92dB. But as I said there are exceptions.



So are you saying that drivers with 87-92dB sensitivities are not as good as drivers with higher sensitivities? I have heard many drivers under 90dB which in my opinion leave Focal for dead but as I said that is my opinion and everyone should realise that speakers are a highly subjective topic. Still I have to say that I think your generalisation about high efficiency drivers being better than lower efficiency drivers is way off the mark.


Damian Ware wrote on Wednesday, November 29, 2006 - 04:57 pm:


As you know every increase in efficiency of 3dB means you can run an amplifier with half the power to produce the same sound level.



Of course but saying one speaker is better than another just because it requires less power to get to a certain volume doesn't necessarily make the more efficient speaker better.


Damian Ware wrote on Wednesday, November 29, 2006 - 04:57 pm:


My aim with my camry was a HiFi system that would the sound the same as my home system, I got close with as you say naturally accurate drivers.

There are many drivers which while clear are overally bright which sound good for about 10 minutes then get harsh on the ears. They also give the impression of being more powerful even though the sound level when measured in dB is actually less. My brother went down this path by putting in the Focal Kevlars, they are one of the better types like this but after 30 minutes I couldnt wait to get out, where as with my system running the Utopia speakers it was very natural and I would still be very happy listening for hrs and hrs at a time.



I have never understood the fascination with Focal products. To me they have always sounded far too forward and bright, especially in the treble, regardless of room acoustics. Their midrange can be impressive (utopia series) and their subs I could take or leave. But in terms of natural, organic sound, for my ears they are not even close to the best. Don't get me wrong I have big respect for them as a company, I was lucky enough to visit their manufacturing and design facilities in France and I know their head designer personally but I just cant rate their product, be it car or home among the best in the world.
Damian Ware
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Wednesday, November 29, 2006 - 09:48 pm, by:  Damian Ware (Frozenpod) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

I didn't say that high efficiency automatically means great sound quality. I would point out the fact that PA have high efficiency but they loose sound quality to achieve. And yes they are specifically designed to do so for live bands, night clubs and such.

As a general rule of thumb a good quality speaker will have a higher efficiency than a poor quality speaker. This doesn't mean that only good quality speakers have high efficiency, some do have low efficiency. I would buy a higher efficiency speaker if I thought they sounded the same quality, as you need less power to run them. The more power you need to run them the more THD you end up with, even with the same amp. So the overall system will be a nicer quality of sound. But there is no point have a 120dB set of EV's that sound rubbish and blow your ear drums out running off a 30W amp.

Forward and bright, depends which ones, the Kevlars are as they are designed to do so. The big thing is though that most people are comparing speakers vs other speakers which is always tough. What you need to do is compare speaker vs the real thing.

Focal speakers from what I have seen is one of the best most accurate speakers in the world. They have a subtansially flatter frequency response than can be heard by the human ear. If anything you shouldn't be able to hear a difference between them and the real thing.

Most speakers while they do a good job for bass they don't have the top end clarity. Try some silver RCA's if you get the chance and that will totally change the sound. It is mind blowing the things that make a difference in the real world but cannot be explained by test measurement.

I think they are great and the only thing I can use to back it up besides the awards they recieve and amazing reports is comparing against live music such as the MSO these are the only things that come close. Yes I do think they are slightly different to every other speaker out there which is one of the reasons I think they are better.
Mark Paddick
Goo Roo
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Wednesday, November 29, 2006 - 11:03 pm, by:  Mark Paddick (Sparks) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

The reason why the valve amp sounds so good and why they still have a dedicated following is the predominance of third order harmonics in the output. This makes up nearly all the distortion with the only other measureable effects being crossover distortion (if it is a push-pull output design and the reason why many expensive valve amps are single ended and therefore relatively low power) and intermodulation distortion. this is where highly efficient speakers are at their best; hanging off a good valve amp.
As a musical instrument amp valve amps are still preferred by many musicians because of their 'sound'. This is a totally different story though. An instrument amp is under no obligation at all to maintain the input signal integrity. It is producing the music not re-producing and all the rules change.

Unfortunately there is no recognised formula for stating distortion effects. THD is the only commonly quoted figure and it includes all forms of distortion.
It just so happens that third order harmonics are not 'objectionable' to listen to and impart a nice warm 'feel' to the sound especially if other distortion products are low. This is why valve amps have such a following. Not because they are particularly spectacular in performance but that the distortion they do produce is not objectionable to the ear. Providing it is only third harmonic then the distortion can be in the several percent region and still sound good.
The classic transistor amp produces mainly second order distortion products and crossover distortion is highish too along with intermodulation. Both are highly irritating and harsh to listen to especially for extended periods.

Later transistor designs essentially got rid of crossover distortion and careful output stage design and layout can reduce the 2nd order harmonics considerably. These amps are technically far superior to the valve amps but still don't quite get there for listening pleasure.

Some (mainly American) designs went as far as to deliberately introduce reasonably high levels of third harmonic distortion, often by including a valve pre-amp stage. This had the effect of masking the relatively low 2nd harmonics and making the whole lot sound 'warm and smooth' just like a really good valve amp. This sort of design attracts a lot of fanatical audiophiles who can't afford the all-valve designs which can be prohibitively expensive. It also allows window shattering sound levels that a valve amp can't produce (at least not cheaply) on its' own.
With some very good FET and Transistor output stage designs some of this style of amp are really very good to listen to even though THD can be quite high.

IC amps came next and some are quite good indeed but they all have two nasty characteristics at least to some extent. Rising distortion with increased load and also with increased frequency.
ALL amplifiers of any shape form or description exhibit these traits but IC amps are worst. Just as bad is their lack of noise immunity. Digital amps can avoid both altogether by careful design but it is still there intrinsically.
Again, all amps will show a rising noise level with frequency and also heat and light too in some cases. This is a fact of life; a law of Physics just like the load/distortion thing. It can be designed around and minimised and in some respects even eliminated from the output but it still is there in all cases, just some are worse than others.

MosFETS made amp design interesting again. They can be used in exactly the same circuits as valves with the same results. Except FETs have better noise immunity and better load characteristics. A FET amp can get away without the output transformer which reduces distortion by another level.
They do have some other problems though. The worst is a tendency to oscillate because of their extremely high input impedance in some circuits. Power amps often become high power generators. They also have a tendency to positive feedback as temperature increases and they can "run away" thermally which is guaranteed destruction for the amp if it doesn't have very sensitive thermal control circuitry which in turn can distort the signal.
FETs can also be used like transistors in very similar output stage designs but have less of a tendency to 2nd harmonic distortion which is good.
They can also be used in high feedback circuits which many purists don't like but ALL amps use it to some extent. Many use only local feedback around a single stage and treat each stage separately. Apparently this is the go if you are an audiophile of the American persuasion. It does make some sense but like all fads is mostly based in bullshit and ignores other pertinent arguments.

Good amp design can reduce many of these problems and the rising distortion with load characteristic is one. Many car audio style amps do use IC amps though and that can make a huge difference. The distortion may not be as high as some but it is there and in the case of the Soarer factory amps (both the Jap and US versions with the upgrade Naka US system being better by far) do exhibit this trait and markedly.
Although only in the 0.2 o 0.4% region below 10kHz it is a factor of 200 times better if the speakers are changed for 8 ohm types. Above 10kHz and it's worse all the way to the top. (this is why I went to the US amps. The Nakamichi is heaps better at the top end in particular). This difference is audible. The downside is reduced power output from the amp (not a huge amount but enough to notice). In the Soarer this power loss can be overcome to some degree by upgrading the 12v feed to the 4 channel power amp. (also helps with 4 ohm load). In fact, since the output current is exactly half in the 8 ohm case stress on the power supply is reduced resulting in lower intermodulation distortion too.

Good system design can reduce some distortion products even further.
Intermodulation distortion is basically caused by different frequencies interfering with each other.
An active crossover design will reduce intermodulation considerably as each amp no longer has a full frequency range input signal. Therefore there are less frequencies to interfere with each other and itntermod goes through he floor with some 3 and 4 way active designs having totally unmeasureable intermod products and stuff all 2nd harmonic either with some of the newer breed of high performance OP amps designed specifically for the purpose.
Any good amp of any design in such a system is going to sound good.
Throw in something like the DEQX stuff and you have midblowing clarity and attack with frequency resposes measured in tenths of decibels across the whole audio spectrum and then some. Not to mention perfectly aligned phase response TO YOU OWN LISTENING POSITION and you are starting to get somewhere. ( http://www.deqx.com/ )
This is the basis of my home system and now DEQX are offering a car oriented system at hugely reduced prices....the Soarer may yet get a final upgrade in sound system.

Once you have gotten to this sort of system with a real effort put into design and some basic good bits it really doesn't matter that much exactly where the bits came from or who made them. They are going to be good and is is quite amazing how several different approaches and design philosophies can result in very similar outcomes. They ALL sound bloody good and most are expensive (ish).
Michael Marchant
TryHard
Victoria
Soarer UZZ32 V8

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Wednesday, November 29, 2006 - 11:06 pm, by:  Michael Marchant (Mavric) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)


Damian Ware wrote on Wednesday, November 29, 2006 - 09:48 pm:

I would point out the fact that PA have high efficiency but they loose sound quality to achieve. And yes they are specifically designed to do so for live bands, night clubs and such.



Yep, that’s what I just said!


Damian Ware wrote on Wednesday, November 29, 2006 - 09:48 pm:


As a general rule of thumb a good quality speaker will have a higher efficiency than a poor quality speaker.



Why?


Damian Ware wrote on Wednesday, November 29, 2006 - 09:48 pm:


Forward and bright, depends which ones, the Kevlars are as they are designed to do so. The big thing is though that most people are comparing speakers vs other speakers which is always tough. What you need to do is compare speaker vs the real thing.




Their entire range with a slight exception for the Utopias have a bright nature. You can tame them with the electronics and cables you use in the system but that is the Focal sound, I have sold many pairs of them across all of their home audio ranges and they all carried the trait of being forward in the treble. Many people mistake that for clarity and a higher level of detail but once you get to hear a wide range of high end speakers you realise that that isn’t the case. You say you need to compare them versus the real thing, fair enough too. Have you ever conducted any blind test between the real thing and the speakers?


Damian Ware wrote on Wednesday, November 29, 2006 - 09:48 pm:


Focal speakers from what I have seen is one of the best most accurate speakers in the world. They have a subtansially flatter frequency response than can be heard by the human ear. If anything you shouldn't be able to hear a difference between them and the real thing.




A flat frequency response is only a small piece of the puzzle. What plays the biggest part in achieving great sound is not the speaker, it’s the room. You can have a ruler flat response but if it is in a poor acoustical environment you will never achieve accurate sound. Add to that this such as cabinet design, resonance control, speaker placement, crossover design, associated electronics, cables and source material and all of a sudden you realise how small a piece of the pie a flat response actually is. It certainly helps, no doubt but it is not the be all and end all of top SQ.


Damian Ware wrote on Wednesday, November 29, 2006 - 09:48 pm:


Most speakers while they do a good job for bass they don't have the top end clarity.




This is possibly a result of listening to Focal a lot. When you hear another speaker it will probably sound flat to you in the treble. This is NOT a result of the other speaker not having “top-end clarity”, you may just be expecting the bright nature of the focal to be there and when it is not you perceive it as being flat.


Damian Ware wrote on Wednesday, November 29, 2006 - 09:48 pm:


Try some silver RCA's if you get the chance and that will totally change the sound. It is mind blowing the things that make a difference in the real world but cannot be explained by test measurement.



You see this makes my point above about the flat response speakers not being everything to audio, there are so many things that affect the sound its ridiculous and many of them can not be measured. I work in high end audio and have heard many many cables, silver, copper, platinum, rhodium plated you name it. I look at silver cables as being the focal speakers of the cable world. The poor ones add edge, glare and brightness which again people perceive as detail and clarity (but its not) and the good quality ones aren’t much better. Copper is by far the most natural sounding conductor I have heard although if you are willing to pay mega bucks for cables the platinum is very impressive too but not worth the extreme increase in price.

Damian Ware wrote on Wednesday, November 29, 2006 - 09:48 pm:


I think they are great and the only thing I can use to back it up besides the awards they recieve and amazing reports is comparing against live music such as the MSO these are the only things that come close. Yes I do think they are slightly different to every other speaker out there which is one of the reasons I think they are better.




Every speaker is different from the next, no doubt about that. Just out of interest, what other brands of speakers have you heard apart from the Focals?
Michael Marchant
TryHard
Victoria
Soarer UZZ32 V8

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Wednesday, November 29, 2006 - 11:15 pm, by:  Michael Marchant (Mavric) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Top post Mark, right on the money

Next time your down in Melbourne you will have to stop by and have a listen to some of our gear, I reckon we would have an example of every type of amp you just mentioned and then some!
Dan McColl
Goo Roo
Victoria
Bog Standard Active

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Wednesday, November 29, 2006 - 11:31 pm, by:  Dan McColl (Hoon) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Jibber Jabber, Too much Jibber Jabber.
Mark Paddick
Goo Roo
ACT
UZZ31 V8 Soarer , JZZ30 TT Soarer

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Wednesday, November 29, 2006 - 11:54 pm, by:  Mark Paddick (Sparks) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

I suspect that in the not-too-distant future systems such as the DEQX are going to completely change our collective outlook regarding good stereo sound. They've certainly changed my outlook and that's only really the start of the Digital age in audio. (disregarding the ubiquitous CD of course...and there are still those who'll only listen to vinyl!!)
Like the rest of the Digital fad there will be some crap produced but in general the advances in the last few years are more spectacular than anything before.

Dan, just 'cos you can't follow it there's no need to get nasty
Dan McColl
Goo Roo
Victoria
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Thursday, November 30, 2006 - 12:30 am, by:  Dan McColl (Hoon) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

I just want what sounds good to my ears.
Mark Paddick
Goo Roo
ACT
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Thursday, November 30, 2006 - 01:17 am, by:  Mark Paddick (Sparks) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

I'll shut up then shall I?
Michael Marchant
TryHard
Victoria
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Thursday, November 30, 2006 - 09:01 am, by:  Michael Marchant (Mavric) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)


Mark Paddick wrote on Wednesday, November 29, 2006 - 11:54 pm:

I suspect that in the not-too-distant future systems such as the DEQX are going to completely change our collective outlook regarding good stereo sound. They've certainly changed my outlook and that's only really the start of the Digital age in audio. (disregarding the ubiquitous CD of course...and there are still those who'll only listen to vinyl!!)
Like the rest of the Digital fad there will be some crap produced but in general the advances in the last few years are more spectacular than anything before.



The Deqx is indeed an impressive product. We have just purchased a Deqx PCD2.6 pre-amp to help with measuring and testing a domestic speaker we are designing & building. Its flexibility is just awesome and I will use it to tune my car system once I have all the new gear in place. Running speakers active makes a lot of sense and many of the top car audio gurus around the world now run active and a few have even purchased a deqx to setup their cars, im just lucky we needed one for the business as they aren't super cheap.
Mark Paddick
Goo Roo
ACT
UZZ31 V8 Soarer , JZZ30 TT Soarer

Posts: 3046
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Thursday, November 30, 2006 - 09:08 am, by:  Mark Paddick (Sparks) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Yeah, $2.5k for a bare bones board isn't cheap but the results are well worth it.
The Motional Feedback systems of Philips and others were incredible performers using accelerometers on the bass speaker cone to provide feedback. This only worked for the bass speakers and was often used to get really good bass from shoe-box sized enclosures.
The DEQX system goes further with calibrated microphones to provide feedback for the entire system and the room or car that it's in.. This allows correction for time, phase, attack, decay and frequency response all in real time (probably more that I forget too). The high end models can even remember and recognise each and every piece of music and store individual corrections to compensate for recording deficiencies. Arthur Bailey would have creamed himself at the mere thought of such a possibility and so would most world renowned audio engineers of the past.
I used my home system to set the car up but now they have a dedicated car setup that I think I'm just going to have to acquire.
Ian Johnston
DieHard
South Australia
UZZ30 GT 4.0

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Saturday, December 16, 2006 - 09:26 pm, by:  Ian Johnston (Ted) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

I think I might just stick to my standard 7 speaker system.
Peter Bullman
Tinkerer
NSW
SC400

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Monday, December 18, 2006 - 05:45 pm, by:  Peter Bullman (Pete) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Where do you guys get time to TYPE all this stuff..??!! Its taken me long enough to READ it..!!!

Top thread though!! Very valuable!! I have understood about 85.87% of the thread.....







........and 0.2586 distortion......!

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