Do I really need an amp like this? NO! But I really want an amp like this!

[davewantsmoore]

2 minutes ago, Sir Sanders Zingmore said:

That looks quite good, yes ?

Less than 1dB down at 20k is gonna be inaudible (at least to my ears)

This much frequency distortion at 20khz means that there is a small amount of phase shift extending octave(s) lower.

 

.... but when we look at the output of the speaker connected to the amp (typically much worse), then it might not seem such a worry.

 

 

[Addicted to music]

11 minutes ago, davewantsmoore said:

This much frequency distortion at 20khz means that there is a small amount of phase shift extending octave(s) lower.

 

.... but when we look at the output of the speaker connected to the amp (typically much worse), then it might not seem such a worry.

 

 

I have to say that some have outstanding hearing for there age to detect -1db @ 20khz.....

 

sad and for me I don’t tick that box!

[davewantsmoore]

2 minutes ago, Addicted to music said:

I have to say that some have outstanding hearing for there age to detect -1db @ 20khz.....

sad and for me I don’t tick that box!

I like to play a trick on people where I switch everything over 10khz on/off ... or boost it by 6dB, or whatever.   

[Addicted to music]

13 minutes ago, davewantsmoore said:

I like to play a trick on people where I switch everything over 10khz on/off ... or boost it by 6dB, or whatever.   

Gold!

[georgehifi]

10 hours ago, davewantsmoore said:

I like to play a trick on people where I switch everything over 10khz on/off ... or boost it by 6dB, or whatever. 

After you told me about all the processing that goes on in your system, I believe they're being polite when you pull this stunt on them, by not saying anything and just there to drink your wine. 

 

Cheers George

[davewantsmoore]

7 hours ago, georgehifi said:

After you told me about all the processing

You may be mistaking me for someone else.... or referring to processing which I used to investigate specific things (like whether said processing was audible).   For example, is the difference between MP3 and CD audible .... are high frequencies audible?    Is group delay audible?....  Are active filters audible (vs passive?)  etc. etc.

 

 

 

Typically in my system I have:

 

Either a passive crossover, or IIR based active filters - ie. ones which are just active equivalents of typical passive filters (so no "room correction" "DRC" or other "phase manipulation).

IIR EQ applied to < 200Hz

 

Sometimes I use FIR type filters (ie. linear phase ones - that don't "occur in nature")  .... but if you read my posts, I find this quite variable (extremely prone to measurement error) and in many ways fundamentally flawed.    Although I still think it's more about "what you do with it", than blaming the tools directly.

 

I don't typically employ driver rolloffs steeper than 24dB/octave (they're just not usually very helpful)  .... so this means either 6dB or 12dB (first or second order) filters.

 

The speaker which I've sold mostly (although not for a few year now)  ... has a cap on the tweeter and a inductor on the woofer (and one parallel network on each driver).

 

 

 

 

You may have heard me talk about "more processing or EQ" .... but this is wrapped up in the speaker design process.    ie. calculating filters for baffle diffraction, or crossovers/EQ ... and a target design curve....   like all speaker designers do.

 

So, yeah <shrug>.   The above is a "lot less processing" than a LOT of people you would encounter, even on this forum....  and almost all of it, is no different to the level of manipulation that you would find in a typical passive crossover speaker.    it is just (sometimes) implemented with active circuits, which affords a lot more flexibility than a passive filter.

 

 

 

 

 

 

[Colin Rutter]

But really efficient easy to drive ones have much more colourations and distortions
 
Cheers George

Oh really! George you should no better than that if you are the George I think you might be [emoji6]

[georgehifi]

10 minutes ago, Colin Rutter said:

Oh really! George you should no better than that if you are the George I think you might be

Not when they have horn colourations, or drivers that are used outside their least distorted zone, with xovers that are either non existent or too low order (shallow) to give and effective hf/lf roll-off so the driver stays clean and in it's linear zone ect ect.

Then there's the multiple driver attack for efficiency all working in the same frequencies, which can never work properly (Bose 901), as even the best drivers cannot all move in perfect unison. 

 

Cheers George

Edited August 17, 2018 by georgehifi

[Happy]

Implementation......

[davewantsmoore]

18 minutes ago, georgehifi said:

even the best drivers cannot all move in perfect unison

Only known to become a problem when the difference is quite large (and the lobes or peaks/dips become significant) .... otherwise it's just 'typical' comb filtering.

 

ESL/panel speakers, and BMR/DML type drivers are an example of this.

[georgehifi]

1 hour ago, davewantsmoore said:

Only "known"

See you counted yourself out of that one.

 

One quality driver working in it's own linear comfort zone, will sound better than a few average ones trying to produce the same sound, because they can never work in perfect unison, there's just too many driver parameters to even match up perfectly, to make them work in perfect unison. As this will have you believe.

https://www.stereophile.com/images/styles/600_wide/public/718tek.promo_.jpg

 

Cheers George  

Edited August 18, 2018 by georgehifi

[davewantsmoore]

30 minutes ago, georgehifi said:

because they can never work in perfect unison

What I was trying to say was that this may cause distortion, yes... but only when the difference is quite significant.

 

So, all else being equal (which is difficult! to arrange) ... the statement that "they will sound better" is mostly false.

 

You can study this effect by studying ESL panels, or BMR type drivers.

[davewantsmoore]

36 minutes ago, georgehifi said:

https://www.stereophile.com/images/styles/600_wide/public/718tek.promo_.jpg

Correct.  This is a terrible idea....  because the "lobes, or peaks/dips, become significant" as mentioned in previous post.  (It is not about the driver parameters not being matched - as there are much bigger issues going on)

Edited August 18, 2018 by davewantsmoore

[georgehifi]

42 minutes ago, davewantsmoore said:

What I was trying to say was that this may cause distortion

It definitely does, the late Richard Timmins speaker maker and reviewer for HiFi Review, tried this many times and had me come and listen on many occasions, while the dynamics were good the sound was better with just one of the same driver but naturally it couldn't go as loud.

BTW these experiments were also overseen by the late Colin Waite AMW/Ottoscan1, 2, and 4 and 3B  and Dr Erni Benson/Ottoscan-3B

The Ottoscan 3B was a beast some 100kg each 4 way with Dr Benson's designed 24db passive xover on all drivers for LP and HP, and needed a beast of an amp to drive them, it was bi-amped ME150's for memory or something similar.

 

Cheers George   

 

 

Edited August 18, 2018 by georgehifi

[davewantsmoore]

1 hour ago, georgehifi said:

It definitely does

No doubt...

 

What I'm taking 'issue' with is your description of when it happens (always) .... and what the mechanism is (multiple drivers not moving perfectly in unison).

 

It is almost certain that what you really heard was not small imperfections in the driver motion.... but the fact that because the drivers were not in the same location, that the acoustic summing was degraded.    It is interesting that this problem (non-coincident drivers) is exacerbated by steeper crossover slopes.

 

 

The reason that so much is known about "multiple drivers not moving perfectly in unison" .... is that is easy to experiment on.   You can observe the driver motion and conclude that they do quite well move in unison (unless something big causes otherwise) ... and you can take multiple drivers and force one or more of them to move 'less than perfectly', and observe the result (quite drastically if you like - much more than would be experience by normal drivers).

[georgehifi]

12 minutes ago, davewantsmoore said:

multiple drivers not moving perfectly in unison

And I'll stick by it, as I had to suffer too much back then with the many A/B listening sessions Richard ask me to compare.

 

Cheers George

Edited August 18, 2018 by georgehifi

[davewantsmoore]

How did comparing it, tell you conclusively what the cause was?

 

[georgehifi]

1 hour ago, davewantsmoore said:

How did comparing it, tell you conclusively what the cause was?

I've already told you Dave, with 3 x speaker designer experts doing the A/B's between multiples and a single of the same, now it's getting boring. Don't tell me you have multiples also, on top of all the processing you do.

 

Cheers George 

[davewantsmoore]

18 minutes ago, georgehifi said:

I've already told you Dave, with 3 x speaker designer experts doing the A/B's between multiples and a single of the same

Sure.  I understand that.... but doing an A/B test and hearing a difference doesn't tell you what the cause is. 

 

Expert speaker designers are aware that typical differences between the motion of two drivers, doesn't cause significant impact .... but that two drivers playing in unison which are non-coincident does.

 

Quote

Don't tell me you have multiples also

I have designed speakers which use "multiples"  (eg. an 2.5-way MTMWW) ....  or a multiple entry horn (like a "unity horn") .... but typically no.

 

Quote

.... on top of all the processing you do.

Now you're just being childish.

 

18 minutes ago, georgehifi said:

now it's getting boring

Talking about speakers is never boring    ....  but this *is* getting tedious.

Edited August 18, 2018 by davewantsmoore

[georgehifi]

54 minutes ago, davewantsmoore said:

doesn't tell you what the cause is. 

Just listen to Bose 901 around the wrong way and you'll get an idea. But then you already have, in your own way.

 

BTW Otto Major and Christian Feillafe are Australia's foremost ESL guys, both say the higher the frequency on ESL panels the closer to center of the panel it emits from, not all over, so there is a difference with what you compared with to multiple drivers. 

Edited August 18, 2018 by georgehifi

[Colin Rutter]

Not when they have horn colourations, or drivers that are used outside their least distorted zone, with xovers that are either non existent or too low order (shallow) to give and effective hf/lf roll-off so the driver stays clean and in it's linear zone ect ect.
Then there's the multiple driver attack for efficiency all working in the same frequencies, which can never work properly (Bose 901), as even the best drivers cannot all move in perfect unison. 
 
Cheers George

I was thinking of a single fullrange on open baffle (Rola 12ux comes to mind) driven with 6L6 pp ul hehe

[georgehifi]

9 minutes ago, Colin Rutter said:

single fullrange

Contradiction in terms that one I'm afraid, no such driver that doesn't have coloration/distortions, closest thing would be an ESL or Planer

 

Cheers George

Edited August 18, 2018 by georgehifi

[davewantsmoore]

4 hours ago, georgehifi said:

Just listen to Bose 901 around the wrong way and you'll get an idea.

Hearing it, won't tell me what causes it.

4 hours ago, georgehifi said:

BTW Otto Major and Christian Feillafe are Australia's foremost ESL guys, both say the higher the frequency on ESL panels the closer to center of the panel it emits from, not all over, so there is a difference with what you compared with to multiple drivers. 

It depends on how the panels are arranged.  (Eg. some have a smaller "HF" panel)

 

My comment was general, and assuming a 'large' panel (which doesn't have to be that large, when we are talking about ~20khz) ...   but you seem to be missing the point.

[georgehifi]

9 hours ago, davewantsmoore said:

It depends on how the panels are arranged.  (Eg. some have a smaller "HF" panel)

Yes and the higher the frequency on either panel the more from the center it comes from. Take it up with Otto Major and Christian Feillafe far more knowledgeable than yourself, you may just learn something. They'll love you. Your so argumentative, is that a Tassie thing or just you, you seem to be missing the point 

Edited August 18, 2018 by georgehifi

[sir sanders zingmore]

1 hour ago, georgehifi said:

Your so argumentative, is that a Tassie thing or just you, 

I’m sure Dave can defend himself from personal attacks but I would say he’s one of the most patient, least argumentative people on SNA. 

He is asking good questions and making intelligent points and people attack him for it yet he never loses his temper.