This is a test of the regsaudioforum email.

Hi REG.  I think this is a great idea.  Let me know what I can do to
help !!!!

PacPaige

Hello from the other side of the dirt pile, (but on the same sheet of
music!)

Charlie Daniell

I am looking forward to spirited discussions.

Cheers

    Thomas

Great idea, Robert.  I signed up as a member.  If you need any help
searching for any back correspondence from the HUG, let me know.  I
probably have it archived on my machine.

TM

Just drop in to say hello from the sunny island - Singapore...

Best Regards
Eric Chua

--- In regsaudioforum@yahoogroups.com, "danvetc" <danvetc@b...> wrote:
> Hello from the other side of the dirt pile, (but on the same sheet of
> music!)
>
> Charlie Daniell

Hello from me too

Richard

Robert,

How much better is the TACT-corrected Harbeth M40 sound over the Z
system-corrected M40 sound in your room? Or is it the other way around?

thanks,

Yip

Dear All,

Anyone has any idea what is the material composition of the RADIAL
driver of Harbeth speakers? Is there any "plastic -bottle' polymer used
as the base material?

Thanks,

Yip

Dear Paige,

Please persuade Robert to put up colored pics of his listening rooms on
this website.

Thanks,
Yip
--- In regsaudioforum@yahoogroups.com, "palisadespaige"
<palisadespaige@y...> wrote:
> Hi REG.  I think this is a great idea.  Let me know what I can do to
> help !!!!
>
> PacPaige

Yip

See the patent

http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=GB2269511&F=0

Richard

------------------------------------------------------------------
-----Original Message-----
From: regsaudioforum@yahoogroups.com
[mailto:regsaudioforum@yahoogroups.com]On Behalf Of yipmangmeng
Sent: 04 May 2005 10:45
To: regsaudioforum@yahoogroups.com
Subject: [regsaudioforum] RADIAL matereial composition.


Dear All,

Anyone has any idea what is the material composition of the RADIAL
driver of Harbeth speakers? Is there any "plastic -bottle' polymer used
as the base material?

Thanks,

Yip





Yahoo! Groups Links

To visit your group on the web, go to:
http://groups.yahoo.com/group/regsaudioforum/

To unsubscribe from this group, send an email to:
regsaudioforum-unsubscribe@yahoogroups.com

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Yip

See the patent

http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=GB2269511&F=0

Richard

------------------------------------------------------------------
-----Original Message-----
From: regsaudioforum@yahoogroups.com
[mailto:regsaudioforum@yahoogroups.com]On Behalf Of yipmangmeng
Sent: 04 May 2005 10:45
To: regsaudioforum@yahoogroups.com
Subject: [regsaudioforum] RADIAL matereial composition.


Dear All,

Anyone has any idea what is the material composition of the RADIAL
driver of Harbeth speakers? Is there any "plastic -bottle' polymer used
as the base material?

Thanks,

Yip





Yahoo! Groups Links

To visit your group on the web, go to:
http://groups.yahoo.com/group/regsaudioforum/

To unsubscribe from this group, send an email to:
regsaudioforum-unsubscribe@yahoogroups.com

Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.

Yahoo! Messenger
- Log on with your mobile phone!

Dear  Robert,

Why is height information heard on two-speaker stereo when there is no
real height info in a stereo signal?

Thanks,
Yip

Can amps really be described as having different PRaT quality?
Why not?

Yip

What qualities create PRaT?  Tighter, thinner midbass?

REG once suggested stuffing the ports of the Harbeth
SHL5 as a possible way to increase PRaT.
--- yipmangmeng <yipmangmeng@...> wrote:
> Can amps really be described as having different
> PRaT quality?
> Why not?
>
> Yip
>
>
>

__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around
http://mail.yahoo.com

I'm wondering about this too. I've experienced it with digital sources.
One sounds as if all the musicians are playing together, in rhythmic
lockstep (where the music demands it), while another sounds as if all
the musicians are playing in the same room, but no longer together, as
it were; the rhythm seems to have drifted. How can this be?

Ron Stiskin
New York

raingrover@... wrote:

>What qualities create PRaT?  Tighter, thinner midbass?
>
>REG once suggested stuffing the ports of the Harbeth
>SHL5 as a possible way to increase PRaT.
>--- yipmangmeng <yipmangmeng@...> wrote:
>
>
>>Can amps really be described as having different
>>PRaT quality?
>>Why not?
>>
>>Yip
>>
>>
>>
>>
>>
>
>__________________________________________________
>Do You Yahoo!?
>Tired of spam?  Yahoo! Mail has the best spam protection around
>http://mail.yahoo.com
>
>
>
>Yahoo! Groups Links
>
>
>
>
>
>
>
>

Welcome, Everybody! I am delighted that things are up and running.

We can go on in detail but let me give a "quickie" on a couple of
the topics already brought up.

First, height: Much of the height "information" we pick up in real
life has to do with frequency response. A bird chirping up in a tree
sounds up partly because the sound , which already contains some
hihg frequencies, is given a kind of shaped response contour by the
pinnae(external ear structure) and this shaped response says "up" to
the brain. You can check the differential response of the ear in
this sense by playing(quietly!) a 7 or 8 kHz tone on your stereo
facing forward as usual, and comparing that with bending your head
forward so your face is pointing towards the floor and the tone is
in effect coming from above your head. The tone will be quite a lot
louder.

In stereo, when high frequencies sounds happen, with lots of 7-8 kHz
content they tend to sound "up" for that reason. Cymbal
crashes "float" for example. Cymbals float in real life too,
actually. Listen carefully to a drum kit: heard as where it is
except that the cymbals rise up.

PRaT: This has got to be phase in the bass, I think.
So what makes it good or bad:
Good: flat, really smooth and flat, and extended response in the
room. Bass in a room is usually "minimum phase"[except for
transition to a subwoofer--that is not!] which means if you make it
flat, you make it phase correct,too.

So
BAD: Amps with rolloff in the subsonice region--which cause
surprisingly large effects far up, much farther up than you would
expect(this is why the Quad amps historically--they may have changed
this--had a sort of warm slightly loose bass character).

BAD: Subwoofer transitions that are not very carefully done, or
corected somehow later. It is hard to get the transition phase
linear. But this turns out to be a kind of unpredictable bit as far
as PRaT are concerned because it is all mixed up with room effects.

Good : Starting with minimum phase bass(eg one bass driver) and
correcting it to flat with a minimum phase EQ!(Most of them are,
including the DSP ones, though the DSP ones do not have to be).

To YMM: With the Z Systems one can get things quite flat and hence
quite phase linear, but the Tact pushes the process further and gets
the bass as "tight" and PRaT correct as possible.

Yes, I agree, to many critics, PRaT is attached to leaning out part
of the lower frequencies, usually the middle bass. This creates an
impression sometimes of tighter bas, but of course it is not really
right, it is just a sort of imitation of being right!!

I have to run off to work, but we can go on with this later.

Once again, welcome!

Robert

----- Original Message -----

From: Ronald Stiskin

To: regsaudioforum@yahoogroups.com

Sent: Wednesday, May 04, 2005 5:44 PM

Subject: Re: [regsaudioforum] PRaT

I'm wondering about this too. I've experienced it with digital sources.
One sounds as if all the musicians are playing together, in rhythmic
lockstep (where the music demands it), while another sounds as if all
the musicians are playing in the same room, but no longer together, as
it were; the rhythm seems to have drifted. How can this be?

Ron Stiskin
New York

raingrover@... wrote:

>What qualities create PRaT?  Tighter, thinner midbass?
>
>REG once suggested stuffing the ports of the Harbeth
>SHL5 as a possible way to increase PRaT.
>--- yipmangmeng <yipmangmeng@...> wrote:
> 
>
>>Can amps really be described as having different
>>PRaT quality?
>>Why not?
>>
>>Yip
>>
>>
>>
>>   
>>
>
>__________________________________________________
>Do You Yahoo!?
>Tired of spam?  Yahoo! Mail has the best spam protection around
>http://mail.yahoo.com
>
>
>
>Yahoo! Groups Links
>
>
>
>
>
>
> 
>

Robert,

Thanks for your informative reply. Re: my experience with PRaT and
digital sources - is it common for a digital source to have non-flat
bass, or bass that is rolled off in the subsonic region? I wouldn't have
thought so. How can I test for this?

Ron Stiskin
New York

regonaudio@... wrote:

>Welcome, Everybody! I am delighted that things are up and running.
>
>We can go on in detail but let me give a "quickie" on a couple of
>the topics already brought up.
>
>First, height: Much of the height "information" we pick up in real
>life has to do with frequency response. A bird chirping up in a tree
>sounds up partly because the sound , which already contains some
>hihg frequencies, is given a kind of shaped response contour by the
>pinnae(external ear structure) and this shaped response says "up" to
>the brain. You can check the differential response of the ear in
>this sense by playing(quietly!) a 7 or 8 kHz tone on your stereo
>facing forward as usual, and comparing that with bending your head
>forward so your face is pointing towards the floor and the tone is
>in effect coming from above your head. The tone will be quite a lot
>louder.
>
>In stereo, when high frequencies sounds happen, with lots of 7-8 kHz
>content they tend to sound "up" for that reason. Cymbal
>crashes "float" for example. Cymbals float in real life too,
>actually. Listen carefully to a drum kit: heard as where it is
>except that the cymbals rise up.
>
>PRaT: This has got to be phase in the bass, I think.
>So what makes it good or bad:
>Good: flat, really smooth and flat, and extended response in the
>room. Bass in a room is usually "minimum phase"[except for
>transition to a subwoofer--that is not!] which means if you make it
>flat, you make it phase correct,too.
>
>So
>BAD: Amps with rolloff in the subsonice region--which cause
>surprisingly large effects far up, much farther up than you would
>expect(this is why the Quad amps historically--they may have changed
>this--had a sort of warm slightly loose bass character).
>
>BAD: Subwoofer transitions that are not very carefully done, or
>corected somehow later. It is hard to get the transition phase
>linear. But this turns out to be a kind of unpredictable bit as far
>as PRaT are concerned because it is all mixed up with room effects.
>
>Good : Starting with minimum phase bass(eg one bass driver) and
>correcting it to flat with a minimum phase EQ!(Most of them are,
>including the DSP ones, though the DSP ones do not have to be).
>
>To YMM: With the Z Systems one can get things quite flat and hence
>quite phase linear, but the Tact pushes the process further and gets
>the bass as "tight" and PRaT correct as possible.
>
>Yes, I agree, to many critics, PRaT is attached to leaning out part
>of the lower frequencies, usually the middle bass. This creates an
>impression sometimes of tighter bas, but of course it is not really
>right, it is just a sort of imitation of being right!!
>
>I have to run off to work, but we can go on with this later.
>
>Once again, welcome!
>
>Robert
>
>
>
>
>
>Yahoo! Groups Links
>
>
>
>
>
>
>
>

Hi Robert

 

With only 4 filters in my Z-Sytems to play with how should I best deploy them?  That is to say if I am working in the sub-200Hz region what is a reasonable target to aim for in terms on flatness at the listening seat? 

 

I take it from what has be said in the past that peaks are worse that dips but is a wide shallow peak worse that a narrow one of larger amplitude?

 

Richard

 

 -----Original Message-----
From: regsaudioforum@yahoogroups.com [mailto:regsaudioforum@yahoogroups.com]On Behalf Of regtas43
Sent: 04 May 2005 17:13
To: regsaudioforum@yahoogroups.com
Subject: [regsaudioforum] Welcome plus PRaT and height information in stereo

Welcome, Everybody! I am delighted that things are up and running.

We can go on in detail but let me give a "quickie" on a couple of
the topics already brought up.

First, height: Much of the height "information" we pick up in real
life has to do with frequency response. A bird chirping up in a tree
sounds up partly because the sound , which already contains some
hihg frequencies, is given a kind of shaped response contour by the
pinnae(external ear structure) and this shaped response says "up" to
the brain. You can check the differential response of the ear in
this sense by playing(quietly!) a 7 or 8 kHz tone on your stereo
facing forward as usual, and comparing that with bending your head
forward so your face is pointing towards the floor and the tone is
in effect coming from above your head. The tone will be quite a lot
louder.

In stereo, when high frequencies sounds happen, with lots of 7-8 kHz
content they tend to sound "up" for that reason. Cymbal
crashes "float" for example. Cymbals float in real life too,
actually. Listen carefully to a drum kit: heard as where it is
except that the cymbals rise up.

PRaT: This has got to be phase in the bass, I think.
So what makes it good or bad:
Good: flat, really smooth and flat, and extended response in the
room. Bass in a room is usually "minimum phase"[except for
transition to a subwoofer--that is not!] which means if you make it
flat, you make it phase correct,too.

So
BAD: Amps with rolloff in the subsonice region--which cause
surprisingly large effects far up, much farther up than you would
expect(this is why the Quad amps historically--they may have changed
this--had a sort of warm slightly loose bass character).

BAD: Subwoofer transitions that are not very carefully done, or
corected somehow later. It is hard to get the transition phase
linear. But this turns out to be a kind of unpredictable bit as far
as PRaT are concerned because it is all mixed up with room effects.

Good : Starting with minimum phase bass(eg one bass driver) and
correcting it to flat with a minimum phase EQ!(Most of them are,
including the DSP ones, though the DSP ones do not have to be).

To YMM: With the Z Systems one can get things quite flat and hence
quite phase linear, but the Tact pushes the process further and gets
the bass as "tight" and PRaT correct as possible.

Yes, I agree, to many critics, PRaT is attached to leaning out part
of the lower frequencies, usually the middle bass. This creates an
impression sometimes of tighter bas, but of course it is not really
right, it is just a sort of imitation of being right!!

I have to run off to work, but we can go on with this later.

Once again, welcome!

Robert

It's usually the amp that rolls off the bass, Ron, not the digital
source or preamp.  Many amps limit power output at very low frequencies
by inserting a capacitor across the output so as to create a high pass
filter.  This was more common in analog's heyday than it is these days.
The goal was to cut down on the power-robbing and woofer-pumping effects
of LP warps played by a cartridge/tonearm combination with its resonance
in the wrong frequency range.  But many amps still are not "direct
coupled" to DC.  That filter causes the bass phase problem Robert is
talking about.

>>> RZangpo2@... 05/04/05 12:31PM >>>
Robert,

Thanks for your informative reply. Re: my experience with PRaT and
digital sources - is it common for a digital source to have non-flat
bass, or bass that is rolled off in the subsonic region? I wouldn't
have
thought so. How can I test for this?

Ron Stiskin
New York

regonaudio@... wrote:

>Welcome, Everybody! I am delighted that things are up and running.
>
>We can go on in detail but let me give a "quickie" on a couple of
>the topics already brought up.
>
>First, height: Much of the height "information" we pick up in real
>life has to do with frequency response. A bird chirping up in a tree
>sounds up partly because the sound , which already contains some
>hihg frequencies, is given a kind of shaped response contour by the
>pinnae(external ear structure) and this shaped response says "up" to
>the brain. You can check the differential response of the ear in
>this sense by playing(quietly!) a 7 or 8 kHz tone on your stereo
>facing forward as usual, and comparing that with bending your head
>forward so your face is pointing towards the floor and the tone is
>in effect coming from above your head. The tone will be quite a lot
>louder.
>
>In stereo, when high frequencies sounds happen, with lots of 7-8 kHz
>content they tend to sound "up" for that reason. Cymbal
>crashes "float" for example. Cymbals float in real life too,
>actually. Listen carefully to a drum kit: heard as where it is
>except that the cymbals rise up.
>
>PRaT: This has got to be phase in the bass, I think.
>So what makes it good or bad:
>Good: flat, really smooth and flat, and extended response in the
>room. Bass in a room is usually "minimum phase"[except for
>transition to a subwoofer--that is not!] which means if you make it
>flat, you make it phase correct,too.
>
>So
>BAD: Amps with rolloff in the subsonice region--which cause
>surprisingly large effects far up, much farther up than you would
>expect(this is why the Quad amps historically--they may have changed
>this--had a sort of warm slightly loose bass character).
>
>BAD: Subwoofer transitions that are not very carefully done, or
>corected somehow later. It is hard to get the transition phase
>linear. But this turns out to be a kind of unpredictable bit as far
>as PRaT are concerned because it is all mixed up with room effects.
>
>Good : Starting with minimum phase bass(eg one bass driver) and
>correcting it to flat with a minimum phase EQ!(Most of them are,
>including the DSP ones, though the DSP ones do not have to be).
>
>To YMM: With the Z Systems one can get things quite flat and hence
>quite phase linear, but the Tact pushes the process further and gets
>the bass as "tight" and PRaT correct as possible.
>
>Yes, I agree, to many critics, PRaT is attached to leaning out part
>of the lower frequencies, usually the middle bass. This creates an
>impression sometimes of tighter bas, but of course it is not really
>right, it is just a sort of imitation of being right!!
>
>I have to run off to work, but we can go on with this later.
>
>Once again, welcome!
>
>Robert
>
>
>
>
>
>Yahoo! Groups Links
>
>
>
>
>
>
>
>

Yahoo! Groups Links
To visit your group on the web, go to:
http://groups.yahoo.com/group/regsaudioforum/
   To unsubscribe from this group, send an email to:
regsaudioforum-unsubscribe@yahoogroups.com
   Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.

FYI:  Thought this might be of interest to you.  This came up in passing
a couple of weeks ago and then again today.  I was curious and asked
Alan about it.  Here's his reply.

>>> "Audio (Alan Shaw)" <audio@...> 05/04/05 12:07PM >>>
Thanks.

Now that we have bought-up all the remaining raw materials that
make RADIAL there is no point wasting money keeping the Patent
Attorneys in luxury! We have enough to make about 100,000 cones:
minimum.

Disappointingly, not one manufacturer has attempted to challenge
our Patent, so no point wasting money defending the IPR. After 10
years if there was going to be a challenge, we'd have heard by
now.

This is the Official Position and you are free to pass it on.

Thanks again

Alan

----- Original Message -----
From: "Tom Mallin" <tmallin@...>
To: <audio@...>
Sent: Wednesday, May 04, 2005 4:54 PM
Subject: RADIAL Patent


> Alan, it just came to my attention that, according to some
> on-line
> information on the European Patent Office Web site, your patent
> ceased
> last year due to non-payment of the patent renewal cost.  I just
> wanted
> to make sure that you were aware of this.  See the patent
> information
> at:
>
>
http://v3.espacenet.com/legal?DB=EPODOC&IDX=GB2269511&F=0&QPN=GB2269511

>
>
>
>
>
>
>

Tom

 

Shame Alan does not understand his exposure to potentially more detailed improvement patents filed by others.

 

Anyway he was only covered against manufacture and sale in the UK.

 

Richard

 

 -----Original Message-----
From: regsaudioforum@yahoogroups.com [mailto:regsaudioforum@yahoogroups.com]On Behalf Of Tom Mallin
Sent: 04 May 2005 18:05
To: regsaudioforum@yahoogroups.com
Subject: [regsaudioforum] Expiration of Alan Shaw's RADIAL Patent

FYI:  Thought this might be of interest to you.  This came up in passing
a couple of weeks ago and then again today.  I was curious and asked
Alan about it.  Here's his reply.

>>> "Audio (Alan Shaw)" <audio@...> 05/04/05 12:07PM >>>
Thanks.

Now that we have bought-up all the remaining raw materials that
make RADIAL there is no point wasting money keeping the Patent
Attorneys in luxury! We have enough to make about 100,000 cones:
minimum.

Disappointingly, not one manufacturer has attempted to challenge
our Patent, so no point wasting money defending the IPR. After 10
years if there was going to be a challenge, we'd have heard by
now.

This is the Official Position and you are free to pass it on.

Thanks again

Alan

----- Original Message -----
From: "Tom Mallin" <tmallin@...>
To: <audio@...>
Sent: Wednesday, May 04, 2005 4:54 PM
Subject: RADIAL Patent


> Alan, it just came to my attention that, according to some
> on-line
> information on the European Patent Office Web site, your patent
> ceased
> last year due to non-payment of the patent renewal cost.  I just
> wanted
> to make sure that you were aware of this.  See the patent
> information
> at:
>
>
http://v3.espacenet.com/legal?DB=EPODOC&IDX=GB2269511&F=0&QPN=GB2269511

>
>
>
>
>
>
>



                                       

If this is the case then I'm still mystified by what I'm hearing. I'm
comparing digital sources played through the same amp, so we can remove
amplification from the equation. Why should one digital source have
better PRaT than another?

Ron Stiskin
New York

tmallin@... wrote:

>It's usually the amp that rolls off the bass, Ron, not the digital
>source or preamp.  Many amps limit power output at very low frequencies
>by inserting a capacitor across the output so as to create a high pass
>filter.  This was more common in analog's heyday than it is these days.
>The goal was to cut down on the power-robbing and woofer-pumping effects
>of LP warps played by a cartridge/tonearm combination with its resonance
>in the wrong frequency range.  But many amps still are not "direct
>coupled" to DC.  That filter causes the bass phase problem Robert is
>talking about.
>
>
>
>>>>RZangpo2@... 05/04/05 12:31PM >>>
>>>>
>>>>
>Robert,
>
>Thanks for your informative reply. Re: my experience with PRaT and
>digital sources - is it common for a digital source to have non-flat
>bass, or bass that is rolled off in the subsonic region? I wouldn't
>have
>thought so. How can I test for this?
>
>Ron Stiskin
>New York
>
>regonaudio@... wrote:
>
>
>
>>Welcome, Everybody! I am delighted that things are up and running.
>>
>>We can go on in detail but let me give a "quickie" on a couple of
>>the topics already brought up.
>>
>>First, height: Much of the height "information" we pick up in real
>>life has to do with frequency response. A bird chirping up in a tree
>>sounds up partly because the sound , which already contains some
>>hihg frequencies, is given a kind of shaped response contour by the
>>pinnae(external ear structure) and this shaped response says "up" to
>>the brain. You can check the differential response of the ear in
>>this sense by playing(quietly!) a 7 or 8 kHz tone on your stereo
>>facing forward as usual, and comparing that with bending your head
>>forward so your face is pointing towards the floor and the tone is
>>in effect coming from above your head. The tone will be quite a lot
>>louder.
>>
>>In stereo, when high frequencies sounds happen, with lots of 7-8 kHz
>>content they tend to sound "up" for that reason. Cymbal
>>crashes "float" for example. Cymbals float in real life too,
>>actually. Listen carefully to a drum kit: heard as where it is
>>except that the cymbals rise up.
>>
>>PRaT: This has got to be phase in the bass, I think.
>>So what makes it good or bad:
>>Good: flat, really smooth and flat, and extended response in the
>>room. Bass in a room is usually "minimum phase"[except for
>>transition to a subwoofer--that is not!] which means if you make it
>>flat, you make it phase correct,too.
>>
>>So
>>BAD: Amps with rolloff in the subsonice region--which cause
>>surprisingly large effects far up, much farther up than you would
>>expect(this is why the Quad amps historically--they may have changed
>>this--had a sort of warm slightly loose bass character).
>>
>>BAD: Subwoofer transitions that are not very carefully done, or
>>corected somehow later. It is hard to get the transition phase
>>linear. But this turns out to be a kind of unpredictable bit as far
>>as PRaT are concerned because it is all mixed up with room effects.
>>
>>Good : Starting with minimum phase bass(eg one bass driver) and
>>correcting it to flat with a minimum phase EQ!(Most of them are,
>>including the DSP ones, though the DSP ones do not have to be).
>>
>>To YMM: With the Z Systems one can get things quite flat and hence
>>quite phase linear, but the Tact pushes the process further and gets
>>the bass as "tight" and PRaT correct as possible.
>>
>>Yes, I agree, to many critics, PRaT is attached to leaning out part
>>of the lower frequencies, usually the middle bass. This creates an
>>impression sometimes of tighter bas, but of course it is not really
>>right, it is just a sort of imitation of being right!!
>>
>>I have to run off to work, but we can go on with this later.
>>
>>Once again, welcome!
>>
>>Robert
>>
>>
>>
>>
>>
>>Yahoo! Groups Links
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>Yahoo! Groups Links
>To visit your group on the web, go to:
>http://groups.yahoo.com/group/regsaudioforum/
>  To unsubscribe from this group, send an email to:
>regsaudioforum-unsubscribe@yahoogroups.com
>  Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
>
>
>
>
>
>
>
>
>Yahoo! Groups Links
>
>
>
>
>
>
>
>

If this is the case then I'm still mystified by what I'm hearing. I'm
comparing digital sources played through the same amp, so we can remove
amplification from the equation. Why should one digital source have
better PRaT than another?

Ron Stiskin
New York

tmallin@... wrote:

>It's usually the amp that rolls off the bass, Ron, not the digital
>source or preamp.  Many amps limit power output at very low frequencies
>by inserting a capacitor across the output so as to create a high pass
>filter.  This was more common in analog's heyday than it is these days.
>The goal was to cut down on the power-robbing and woofer-pumping effects
>of LP warps played by a cartridge/tonearm combination with its resonance
>in the wrong frequency range.  But many amps still are not "direct
>coupled" to DC.  That filter causes the bass phase problem Robert is
>talking about.
>
> 
>
>>>>RZangpo2@... 05/04/05 12:31PM >>>
>>>>       
>>>>
>Robert,
>
>Thanks for your informative reply. Re: my experience with PRaT and
>digital sources - is it common for a digital source to have non-flat
>bass, or bass that is rolled off in the subsonic region? I wouldn't
>have
>thought so. How can I test for this?
>
>Ron Stiskin
>New York
>
>regonaudio@... wrote:
>
> 
>
>>Welcome, Everybody! I am delighted that things are up and running.
>>
>>We can go on in detail but let me give a "quickie" on a couple of
>>the topics already brought up.
>>
>>First, height: Much of the height "information" we pick up in real
>>life has to do with frequency response. A bird chirping up in a tree
>>sounds up partly because the sound , which already contains some
>>hihg frequencies, is given a kind of shaped response contour by the
>>pinnae(external ear structure) and this shaped response says "up" to
>>the brain. You can check the differential response of the ear in
>>this sense by playing(quietly!) a 7 or 8 kHz tone on your stereo
>>facing forward as usual, and comparing that with bending your head
>>forward so your face is pointing towards the floor and the tone is
>>in effect coming from above your head. The tone will be quite a lot
>>louder.
>>
>>In stereo, when high frequencies sounds happen, with lots of 7-8 kHz
>>content they tend to sound "up" for that reason. Cymbal
>>crashes "float" for example. Cymbals float in real life too,
>>actually. Listen carefully to a drum kit: heard as where it is
>>except that the cymbals rise up.
>>
>>PRaT: This has got to be phase in the bass, I think.
>>So what makes it good or bad:
>>Good: flat, really smooth and flat, and extended response in the
>>room. Bass in a room is usually "minimum phase"[except for
>>transition to a subwoofer--that is not!] which means if you make it
>>flat, you make it phase correct,too.
>>
>>So
>>BAD: Amps with rolloff in the subsonice region--which cause
>>surprisingly large effects far up, much farther up than you would
>>expect(this is why the Quad amps historically--they may have changed
>>this--had a sort of warm slightly loose bass character).
>>
>>BAD: Subwoofer transitions that are not very carefully done, or
>>corected somehow later. It is hard to get the transition phase
>>linear. But this turns out to be a kind of unpredictable bit as far
>>as PRaT are concerned because it is all mixed up with room effects.
>>
>>Good : Starting with minimum phase bass(eg one bass driver) and
>>correcting it to flat with a minimum phase EQ!(Most of them are,
>>including the DSP ones, though the DSP ones do not have to be).
>>
>>To YMM: With the Z Systems one can get things quite flat and hence
>>quite phase linear, but the Tact pushes the process further and gets
>>the bass as "tight" and PRaT correct as possible.
>>
>>Yes, I agree, to many critics, PRaT is attached to leaning out part
>>of the lower frequencies, usually the middle bass. This creates an
>>impression sometimes of tighter bas, but of course it is not really
>>right, it is just a sort of imitation of being right!!
>>
>>I have to run off to work, but we can go on with this later.
>>
>>Once again, welcome!
>>
>>Robert
>>
>>
>>
>>
>>
>>Yahoo! Groups Links
>>
>>
>>
>>
>>
>>
>>
>>
>>   
>>
>
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>

I don't see any particular way that the CD player's digital part
would shift bass phase, but I wonder about the ananlog part: How many
CD players will really put out a DC voltage when the digital signal
is constant?
Incidentally, the roll off and consequent phase shifting is
everywhere in audio--how many microphones have really extended bass,
for example?

And virtually no one does the correction needed to fix this kind of
thing.

Actually, with DSP correction you may end up with better phase in the
bass than you are getting in the source material!!

About how to use relatively few coefficients of EQ in the bass,
either digital or analogue:

Experimentation is the rule, but for a start I would try to get rid
of big peaks. The peaks "ring" in a way that most people find
somewhat annoying. If you get the peaks down , you may find yourself
quite happy, happy enough not to need to spend more money on another
EQ unit with more coefficients.

The source material is so often peculiar in this regard that maybe it
is not worth it to go too crazy, but still . there is something
really cool in musical as well as theortical terms about the
absolutely smoothed out and precisely defined bass.

In live orchestral music , there is a LOT of detail in the bass which
often turns to mush in reproduced playback.

It is not just rock people who need bass definition!

REG

This is a tough one. I think you would need a special test disc with
a DC signal(same digital item on every sample) and then a DC volt
meter(that part is easy at least) to see whether anything came out.
Maybe a person clever with computers could make such an item by
hand, so to speak on a computer and then put it on a CD. But I am
not sure how to do this. Any computer people here?

Manufacturers ought to be willing to tell you the low end response
of their players but I have never actually seen such a spec listed.

Everyone seems to assume that because it is no problem to RECORD
digital down to DC that it will automatically be played back flat to
DC.

TO tell you the truth, I have never really noticed any problems I
would attribute to this particular thing but there is no doubt that
it is noticable in principle.

Do you all know about the "famous" KEF demos?
If not, a qucik summary:
KEF took a speaker flat to around 30 Hz and played material
(orchestral music) that stopped at 40 Hz essentially(41 Hz is the
bottom note of the double bass viol). Then they inserted a device
that EQed the speaker to flat to below 5 Hz, with no change in the
response above 40 Hz, so the only effect was linearization of phase,
in the 40 Hz up region. Of course the speaker could not really put
out 5 Hz at any appreciable level, but it was "small signal" EQed to
flat down to there.

The result: Everyone could hear the difference. The linearization of
phase in the nothing-below-40-Hz material was really obvious, with
bass viol parts become much mroe defined in pitch and articulation
etc.(I remember some description about a bass part of a Sibelius
Symphony that had alternate B B flat--or maybe simultaneous) that
was all cleaned up to the point of being audible and clear where it
had been mush before.) This was a blind test repeatable result.

So there you have--the extreme bottom matters on account of phase
even when it is not really in the music in terms of frequency
response.(There is a similar effect at teh top end but it is smaller
for technical reasons--low pass filters causeless in band pahse
shift than high pass ones).

REG

Ok, I will see that he posts pictures of his listening rooms on the
site.   Good idea, thanks.