So Thorsten has broken cover ...

[murray johnson]

No I haven't heard those, only the very large set up with lots of Bryston boxes. The principle problem would, I imagine, be the same though. Large excursions and hefty cones are to my ears not a good idea.

 

[anon_bb]

Only designs I have heard. The altecs I admitted I havent heard. They might well be very good.

I referred to specific examples in each case that I had heard and dismissed as inferior - I made no blanket statements such as "pmc is the best a speaker can ever be" as you seem to be claiming.

You said I was lying last time until you rang the shop and confirmed it.


Rubbish in rubbish out SSB!

 

[anon_bb]

What is wrong with a hefty bass cone?

 

[sideshowbob]

You said I was lying last time until you rang the shop and confirmed it.

What are you on about, I didn't ring the shop at all. It's plausible that you heard ATCs at Cornflake, since they stock them. It's highly inplausible you've heard JBLs in a shop, given the lack of UK distribution.

I don't believe you. Tell me where you heard them.

-- Ian

 

[Markus S]

What is wrong with a hefty bass cone?

That it's hefty.

 

[murray johnson]

Heft generally means weight. The answer is in the question.

Trying to start and stop something heavy is difficult to do accurately. It is easier to stop and start something lighter. It also helps if you don't have to move it as far to get the same spl. The further any voice coil gets from its rest position the less linear the magnetic field is and the more distortion there will be.

If however you are after high power handling and making alot of noise then fine, use a dustbin lid.

 

[KUB3]

RE: AML1. A carbon composite honeycomb 6" cone doesn't weigh much. Plus look at the magnet!

I presume a 15" doped paper volt driver's cone would weigh a fair bit though. Anyway doesn't that help it reach lower Hz? Besides, when you have 1kw per driver that controls them, surely?! (Can't comment, as I've only had the smaller carbon 10" and 6", not the large paper ones)

(Thanks for use of your hand, Tension)

 

[Stereo Mic]

Two questions if I may for our little troll before he starts his homework

Firstly, why is it that none of the numerous ZG members that have visited your little flat have come forth to tell us all we are wrong and that your system is indeed the best they have ever heard?

And secondly, if it's dynamics you want, why bother with a turntable. Why not use a £30 CD player instead?

 

[KUB3]

... into a benchmark dac1

 

[anon_bb]

Well actually only two have heard it. Both with a dvd recorder feeding into the behringer deq dac which is hardly ideal. As I recall both reviews were effusive And its come on a long way since then.

You might want to consider slew and bandwidth MJ. For a bass cone the required slew is quite low. For a large cone (say 2*12" plus) the excursion required is not large. A bass cone doesnt have to stop and start that suddenly - the leading bass edges are given by the mid and treble... think about what happens if you decompose a signal with FFT. Surely a heavy bass cone with the desired bandwidth can produce the top frequency sine wave required as well as a lighter driver which also has the same bandwidth?

Well... because turntables sound more dynamic?

 

[ShinOBIWAN]

Hi

Nope! don't agree at all!

That's OK. We all have opinions.

Any thoughts on the former part of that post?

Dynamics and SPLs are entirely different things.

Dynamics and SPL are completely interelated. You need SPL for big dynamic range, which was my point.

A system that has a large contrast between peak and background noise would therefore have a large difference between lowest SPL and highest. Don't confuse this with the volume control on your amp

Don't fixate on this too much because it wasn't my main point, you should take a look at step/impulse response for a more accurate indicator of the rise and fall nature of a loudspeaker.

SPL being a matter of volume, Dynamics being a matter of contrast.

But didn't I say:

About dynamics: I think they come predominately from realistic SPL's. And the system needs to play at those levels whilst still tracking the source accurately. That makes sense because its only higher SPL's that have the neccessary headroom to give the range needed between peak and noisefloor to make us start to believe that the sound is proportional to what you'd expect in a traditional setting.

You can have huge dynamic micro and macro swings with low SPL.

Micro, macro? Aren't you just glorifying dynamic range? Can't we leave the audiophile speak out of this and call it what it is.

 

[KUB3]

Where's Merlin? He always argues the bigger the cone the better. Thus heavier I guess...

 

[anon_bb]

Indeed.

Its a short step from there to nonsense such as "inner detail".

 

[KUB3]

I had an in store demo once of a range of identical infinity subs of various sizes. Each were mounted in sealed cabs and one could press a button and swap between them whilst music was playing. My impressions in a large room were:

a) 8" were exceptionally accurate
b) 10" was louder and deeper but noticable slower (blurred)
c) 15" was very blurred and slow sounding.

At the time I preffered the 10", as it was accurate-ish, but had a bit of a grungy dirty low end to it. Not so much hifi, but good fun.

It was also a factor the same amp was used in each case - albeit a large one. What's the rule with cone area and required amp power? - Doesn't it need to quadrouple with double the area - to maintain the same accuracy, or something?...

(Now my hifi is more like the sound those 8", btw)

 

[anon_bb]

For the same LF cutoff? If not its hardly a level playing field - units that dont go as deep often sound subjectively faster all things being equal, plus lets not forget the room.

 

[bottleneck]

Shinobowain

I think my meaning didn't come across in my post.

People often associate high SPL with dynamics.....i.e. - "my system goes very loud, listen to the loud bangs and thumps!"

Dynamic indications in music are often gradual, often subtle. A highly dynamic transducer can illustrate amazing dynamics even at very low SPL.

Let me take a quotation from Wikipedia to illustrate my point:



"Dynamic indications are relative, not absolute. mp does not indicate an exact level of volume, it merely indicates that music in a passage so marked should be a little louder than p and a little quieter than mf.

Gradual changes

In addition, there are words used to indicate gradual changes in volume. The two most common are crescendo, sometimes abbreviated to cresc, meaning "get gradually louder"; and decrescendo or diminuendo, sometimes abbreviated to decresc and dim respectively, meaning "get gradually softer". Signs called "hairpins" are also used to stand for these words. These are made up of two lines which connect at one end and get gradually further apart. If the lines are joined at the left, then the indication is to get louder; if they join at the right, the indication is to get softer. The following notation indicates music starting moderately loud, then becoming gradually louder and then gradually quieter: "



Earlier in this thread BBV said that his PMC speakers are more dynamic than a pair of Avanteguarde horns.

Clearly, when we take the term ''dynamics'' in it's whole context encorporating gradual changes in music and subtle dynamic shifts (the difference between micro and macro dynamic changes I was illuding to earlier) they are not.

I'm sure that large PMC speakers have greater power handling capacity, are capable of greater SPL and do not of course have any colouration from the horn, but more dynamic using the full range of the term? no.

 

[murray johnson]

Hi Kub,

a 6" bass driver has to move in and out along way to shift any significant air at LF. imho this isn't a good thing, regardless of the number of poor quality watts stuffed up it.

there's also a little more to magnets than simply their physical size.

 

[anon_bb]

They were when I heard them! Subtle shifts were more easily discernible using the PMC.

I think dynamics only really has one meaning. Micro dynamics is surely an oxymoron.

 

[ShinOBIWAN]

RE: AML1. A carbon composite honeycomb 6" cone doesn't weigh much. Plus look at the magnet!

I presume a 15" doped paper volt driver's cone would weigh a fair bit though. Anyway doesn't that help it reach lower Hz? Besides, when you have 1kw per driver that controls them, surely?! (Can't comment, as I've only had the smaller carbon 10" and 6", not the large paper ones)

Nice driver Simon! No wonder the AML1 has positive comments on the bass.

Again this is my opinion, so please don't be offended if it doesn't mate up with your own - we're all out to enjoy ourselves anyway.

A good bass driver is one with a low mms and very high motor strength. What is less ideal is the monster drivers you see with 70mm of peak-peak xmax and 300-400g of mms with a BL product of 15 or so; think Adire Tumult, SVS subs etc. etc. These monster drivers certainly allow for a single driver sub to plough the depths in a manner suitable for HT and big thrills but the one I've heard all sound off and by that I mean muted and generally 'forced' sounding.

You should also realise that distortion at Fs(driver resonance) is high. Best to get this out of the operating passband of the sub design. Would you cross a tweeter or mid with its driver resonance in the passband? No. So why do virtually all subs do it? Convienence, costs, size etc. pick one. The subs I'm working on move the Fs out of harms way and combine low mms and high motor strength.

To get the mms down you'll need to primarily sacrifice Fs and that means you'll need more drivers to hit the higher SPL's equivalent to a driver with a lower Fs. What your doing in effect is increasing the radiating area, lowering the moving mass per driver unit whilst coupling that to high motor strength - an altogether more natural approach. You don't need big displacement per driver either, you need that low moving mass, high motor strength and then decide what SPL/distortion levels are suitable and increase the number of drivers to suit. Of course domestic settings dictate much.

That's my take after much experimenting with sub drivers built to all different kinds of philosophies.

 

[murray johnson]

If you listened to AG Trios and compared them with the PMC system I heard (which I think is the same as yours) you might realise that in terms of reproducing dynamic range there is little comparison to be made. I would also doubt that the PMC's would get anywhere near the SPLs you can generate with the AG system (not at least without massive amounts of accompanying distortion)

There are better horn speakers than the Trio's + basshorn but in terms of systems that are commercially available they take some beating and speakers like yours don't even get close imho.

The bottom line BBV is that you like that PMC sound. I regard it as unnatural, inaccurate and rather offensive. We'll have to agree to differ on that. You should try to hear a properly installed horn system though. I actually think you'd like it.