Passive Speakers

[idc]

Is there a strong corrleation between the obvious of being able to reproduce bass with a big woofer, or a correlation between anything and sound quality?

 

[lindsayt]

...It's also worth mentioning that everything I've said about active crossovers isn't my own subjective opinion. I'm just repeating facts which have been established for several decades in the professional audio industry and are scientifically proven to be the best way to reproduce music with the least amount of distortion.

Don't take my word for it - try reading a book on the subject if you're interested. It'll teach you much more about our hifi hobby than any magazine or forum will.

Facts? You mean the highly selective facts posted by Martin Grindrod on the AVI forum? Where he choses to ignore a number of facts that I've already mentioned in this thread that contradict his conclusions?

Here's another fact for you: it is not possible to measure THD+N in amplifiers, active crossovers, passive crossovers when we're in the realms of nano to milliwatt power levels with traditional measuring equipment. The measuring equipment has too much internal electrical noise to measure this distortion at such low power levels. This means that I can confidently predict that none of the text books that you've mentioned will contain distortion measurements that demonstrate that active crossovers produce less distortion than passive ones in all circumstances.

Have you ever looked at a range of op amp data sheets? Google "Analog Devices op amp" and follow the links to look at a variety of data sheets. When looking at these data sheets you can do your own rough calculations to work out how much voltage will be going through the active crossover at in room volumes of 30 to 60dbs. IE we will be in the area off the left hand edge of the graphs. This will tell you far more about the distortion characterstics of op amp based active crossovers than any text books or the entire contents of the AVI forum.

 

[John Duncan]

Let's not start a fight, eh? I'm just curious to know what these tests tell us. Has anybody worked out which ones are actives and which are passives and the relative distortion of each?

 

[oldric_naubhoff]

So what do those graphs add to our knowledge of passive and active speakers? I'm too lazy to work it out and I know how you like this stuff.

maybe; a good speaker is one that measures well. and not if it's active or passive.

Do those graphs bear that out? Can you tell me where and how if they do?

all I can do is tell how to interpret the graphs. I'll leave the analysis for you to do.

first set of graphs (the colorful one) represents frequency response (black line high above) versus harmonic distortion component of the speaker in question. having ruler flat freq response is important because you want the speaker to follow the input signal as faithfully as possible. if the speaker don't play certain frequencies as loud as they should be played it's no good (that includes too quiet - freq dip - is no good and too loud - freq lift - is no good as well). however, I think that even more important feature of every speaker is how they cope with harmonic distortion. the lower the better, because you only want to hear the frequencies that are there in the original signal, not those created in addition by the speaker. I'd say -50dB below original signal for harmonic distortion is very respectful for a speaker. (but then there are ESLs which easily reach -70dB for 2nd harmonic). so basically, what to look for in those graphs is the bigger difference between black line and colorful ones the better. this indicates good quality drivers used.

the second set of graphs is so called "step response". this is the one which looks like EKG. this graph shows time coherence of the speaker. text book graph should look like a right triangle with bent long/right arm. (single driver speaker come closer to this theoretical ideal than others). you see overshot in most of the graphs. it means the tweeter leads the signal and then in hands down to midwoofer and woofer (in case of 3-way speaker). where you have a "lazy" bump behind the rapid rise it means you're most likely dealing with a 3-way speaker. you want a clean line in this graph. any irregularities indicate poorly damped/ designed drivers because they don't stop on the proverbial "dime" but continue vibrating and making sounds they shouldn't to. as you look at the graphs you realise that some speakers are more time coherent and some not so much.

the third set of graphs, the busy one, is so called "waterfall plot", due to its graphic representation. what is shows is how fast the drivers settle. the faster the better, of course. the ideal graph should look like a vertical wall, with no ridges (which indicate resonances) and bumps (which indicate slow decay of the driver). in this graph what happens say above 1000Hz is most important.

everybody wants a speaker with flat freq response, low distortion, fast decay and time coherent. but if I were to sacrifice one characteristic so I could have the other perfect it would be the freq response. your room will wreck even the flattest response. and with low harmonic distortion, perfect step response and vertical waterfall plot you'll know that you have extremely clean sounding speaker that images perfectly to boot.

that's in a nutshell. hope it helps.

 

[oldric_naubhoff]

I would be interested in an answer as well. Is there any correlation between how a speaker measures and subjective reports of sound quality?

I once read (don't know where now) that there was some ABX test of speakers which suggested a positive correlation between linear freq response and perceived quality of sound it reproduced.

AFAIK THD in amps was extensively researched in the 50s and they came to conclusion that anything above 2% (maybe lower) is audible - no good.

 

[oldric_naubhoff]

Is there a strong corrleation between the obvious of being able to reproduce bass with a big woofer, or a correlation between anything and sound quality?

take look at harmonic distortion graphs again and note how (in most cases) distortion rises below 100Hz mark. this indicates a smallish woofer was used in that particular speaker. small woofers (like typical 6,5") can play low. but the drawback is that they introduce massive amounts of harmonic distortion higher up the spectrum with it. so you get "richer" than it should sound in the mid bass. add to that exploitation of bass reflex ports and you get speaker which plays commendably low but the bass gets "muddied" and indistinct.

(I should know. I used to have 2-way ported monitors with a 5,5" midwoofer and now it's some 360sq inch bass panel. mid bass resolution is really improved.)

 

[bigblue235]

The differences aren't huge but they are there and they are noticable. Try visiting a pro audio shop and have a listen to a range of different speakers yourself. I'm sure that you'll be able to hear the extra clarity and bass control that many active speakers have.

Based on the info in this thread, I'm not so sure

 

[steve_1979]

The differences aren't huge but they are there and they are noticable. Try visiting a pro audio shop and have a listen to a range of different speakers yourself. I'm sure that you'll be able to hear the extra clarity and bass control that many active speakers have.

Based on the info in this thread, I'm not so sure

It sounds like you've already made your mind up about active speakers without actually listening to any?

I'm confident that if you (or anyone else reading this thread) is willing to visit a pro audio shop with an open mind and audition some £2000 Genelec speakers, you'll hear a level of clarity that's a step up from any £2000 passive system. I'm not saying that there's a vast night and day difference, but there is an easily noticable improvement across the whole frequency range and I'm sure that you'll be able to hear it.

 

[plastic penguin]

There's another possibility: I'm hating these active Vs passive type threads. At the end of the day actives are another format added to this wonderful hobby/obsession.

I won't comment on the virtues of actives, purely because I have absolutely zero knowledge of actives. However, trying to bring some equilibrium to the subject, this is my theory: I know from personal experience that system matching is something I've always loved. Like fox hunters it's the chase or testing of different makes that gives the full buzz. Nevertheless, it is a complete minefield, and can go belly-up before you know it. Sometimes you will make an impulse buy and then find the synergy isn't quite upto scratch.

With active speaker that pitfall is totally eliminated. In terms of AVI and Dynaudio actives (I think) they have a dac as well as an amp, and I'm pretty sure the farther you go up the chain the more bells and whistles you'll find. Just by pure definition the active has cracking synergy: no speaker to match... CDP or amp. All there inside a single enclosure.

This won't account or be appropriate to everyone, but I'm sure it explains some people's findings with actives.

As I said earlier, this is just my personal theory.

 

[steve_1979]

There's another possibility: I'm hating these active Vs passive type threads. At the end of the day actives are just another format added to this wonderful hobby/obsession.

I won't comment on the virtues of actives, purely because I have absolutely zero knowledge of actives. However, trying to bring some equilibrium to the subject, this is my theory: I know from personal experience that system matching is something I've always loved. Like fox hunters it's the chase or testing of different makes that gives the full buzz. Nevertheless, it is a complete minefield, and can go belly-up before you know it. Sometimes you will make an impulse buy and then find the synergy isn't quite upto scratch.

With active speaker that pitfall is totally eliminated. In terms of AVI and Dynaudio actives (I think) they have a dac as well as an amp, and I'm pretty sure the farther you go up the chain the more bells and whistles you'll find. Just by pure definition the active has cracking synergy: no speaker to match... CDP or amp. All there inside a single enclosure.

This won't account or be appropriate to everyone, but I'm sure it explains some people's findings with actives.

As I said earlier, this is just my personal theory.

You make some good points and I completely agree. At the end of the day actives are just another choice that's available to us in this wonderful hobby.

I fully understand how the box swapping and system matching eliment is a big part of the fun for many people and it's also very interesting to read about too. I don't have anything against passive speakers either. In fact I use passive speakers myself, they sound great and I'm very happy with them. All that I've been trying to do in these threads is objectively explain the advantages that actives offer.

My advice to any hifi enthusiasts is to listen to as many different types of system as possible. Active, passive, separates, all-in-ones, AV, or whatever and go with what works for you. And most importantly don't forget to enjoy the music.

Peace.

 

[Frank Harvey]

So does this mean that all this squabbling between passive and active that started since "the invasion", it turns out its a non issue?! Wow, all that effort on both sides for nothing

 

[plastic penguin]

So does this mean that all this squabbling between passive and active that started since "the invasion", it turns out its a non issue?! Wow, all that effort on both sides for nothing

Bloody hope so. It's farcical, hence why I've generally kept clear of "these" types of threads. I'm feeling rather punch drunk by 'them and us' squabbles.

 

[idc]

I would be interested in an answer as well. Is there any correlation between how a speaker measures and subjective reports of sound quality?

I once read (don't know where now) that there was some ABX test of speakers which suggested a positive correlation between linear freq response and perceived quality of sound it reproduced.

AFAIK THD in amps was extensively researched in the 50s and they came to conclusion that anything above 2% (maybe lower) is audible - no good.

Possibley Harman Internation, the speaker maker who also own the headphone brand AKG. They have a very fancy blind testing room for speakers. It is their tests that have found speakers pass ABX better than any other part of the hifi chain.

 

[idc]

Is there a strong corrleation between the obvious of being able to reproduce bass with a big woofer, or a correlation between anything and sound quality?

take look at harmonic distortion graphs again and note how (in most cases) distortion rises below 100Hz mark. this indicates a smallish woofer was used in that particular speaker. small woofers (like typical 6,5") can play low. but the drawback is that they introduce massive amounts of harmonic distortion higher up the spectrum with it. so you get "richer" than it should sound in the mid bass. add to that exploitation of bass reflex ports and you get speaker which plays commendably low but the bass gets "muddied" and indistinct.

(I should know. I used to have 2-way ported monitors with a 5,5" midwoofer and now it's some 360sq inch bass panel. mid bass resolution is really improved.)

That comes over as the difference between a well made speaker and a rubbish one can be correlated to measurements. I presume as speakers get closer in terms of being well made, subjective reports of improved SQ will no longer correlate to measurements.