Tweeter choice
 

On 21/12/2013 03:58, gregz wrote:
"Dave Plowman (News)" wrote:
In article
,
gregz wrote:
The first thing is considering dB/ watt and system integration.

dB per watt isn't actually much of a worry in an active system.

Watts per mid and woofer ? Tells nothing.

Just attempting to give a rough guide on how much level the tweeter has to
handle. If that didn't matter they'd all be the same.


Then talk driver sensitivity.

You're not paying attention. It's an active design. Sensitivity doesn't
matter.
Neither does phase if there's a decent overlap between frequency ranges
of mid and tweeter.
And if you use a digital crossover with adjustable delay you can tweak it
according to whether the listener is sitting or standing.


--
Eiron.

Tweeter choice
 

In article
,
gregz wrote:
"Dave Plowman (News)" wrote:
In article
,
gregz wrote:
The first thing is considering dB/ watt and system integration.

dB per watt isn't actually much of a worry in an active system.

Watts per mid and woofer ? Tells nothing.

Just attempting to give a rough guide on how much level the tweeter
has to handle. If that didn't matter they'd all be the same.


Then talk driver sensitivity.

And just how does the sensitivity give any indication as to the maximum
SPL the unit can deliver?

--
*Puritanism: The haunting fear that someone, somewhere may be happy.

Dave Plowman London SW
To e-mail, change noise into sound.

Tweeter choice
 

"Eiron"

You're not paying attention. It's an active design. Sensitivity doesn't
matter.


** It always matters.

For one reason, taken along with power rating, it sets the max available
SPL.

For another, with a given max drive power, it sets the available head room
( in dBs) for peaks

FYI:

the very low ( 80 dB/watt ) figure quoted for the KEF T27 is suspicious.

http://p10hifi.net/planet10/TLS/driv.../T27-dataS.gif

KEF were not quoting sensitivity the same way that is normally used today.




..... Phil

Tweeter choice
 

On Sat, 21 Dec 2013 22:16:20 +1100, "Phil Allison"
wrote:


"Eiron"

You're not paying attention. It's an active design. Sensitivity doesn't
matter.


** It always matters.

For one reason, taken along with power rating, it sets the max available
SPL.

For another, with a given max drive power, it sets the available head room
( in dBs) for peaks

FYI:

the very low ( 80 dB/watt ) figure quoted for the KEF T27 is suspicious.

http://p10hifi.net/planet10/TLS/driv.../T27-dataS.gif

KEF were not quoting sensitivity the same way that is normally used today.




I suspect that the low 80dB at 1 watt rating is due to pink noise
being specified. 1 watt of pink noise will have a great deal less than
1 watt of power in the tweeter band.

d

Tweeter choice
 

On Sat, 21 Dec 2013 11:49:42 GMT, (Don Pearce) wrote:

On Sat, 21 Dec 2013 22:16:20 +1100, "Phil Allison"
wrote:


"Eiron"

You're not paying attention. It's an active design. Sensitivity doesn't
matter.


** It always matters.

For one reason, taken along with power rating, it sets the max available
SPL.

For another, with a given max drive power, it sets the available head room
( in dBs) for peaks

FYI:

the very low ( 80 dB/watt ) figure quoted for the KEF T27 is suspicious.

http://p10hifi.net/planet10/TLS/driv.../T27-dataS.gif

KEF were not quoting sensitivity the same way that is normally used today.




I suspect that the low 80dB at 1 watt rating is due to pink noise
being specified. 1 watt of pink noise will have a great deal less than
1 watt of power in the tweeter band.

d

Quick calculation. With a 3kHz cutoff, the tweeter level using pink
noise is about 6dB low. That would make the sensitivity measured in
the normal way a much more reasonable 86dB from 1W.

d

Tweeter choice
 

Don Pearce wrote:

I suspect that the low 80dB at 1 watt rating is due to pink noise
being specified. 1 watt of pink noise will have a great deal less
than 1 watt of power in the tweeter band.

d

Quick calculation. With a 3kHz cutoff, the tweeter level using pink
noise is about 6dB low. That would make the sensitivity measured in
the normal way a much more reasonable 86dB from 1W.

The standard KEF target efficiency was 10 watts to produce 96 dB at one
meter back then, my original KEF Coda's are spec'ed at 19 watts, I reckon it
takes their puny bass-range in account.

d

Kind regards

Peter Larsen

Tweeter choice
 

On Sat, 21 Dec 2013 13:05:14 +0100, "Peter Larsen"
wrote:

Don Pearce wrote:

I suspect that the low 80dB at 1 watt rating is due to pink noise
being specified. 1 watt of pink noise will have a great deal less
than 1 watt of power in the tweeter band.

d

Quick calculation. With a 3kHz cutoff, the tweeter level using pink
noise is about 6dB low. That would make the sensitivity measured in
the normal way a much more reasonable 86dB from 1W.

The standard KEF target efficiency was 10 watts to produce 96 dB at one
meter back then, my original KEF Coda's are spec'ed at 19 watts, I reckon it
takes their puny bass-range in account.


96dB at 10W corresponds exactly with 86dB at 1W.

d

Tweeter choice
 

On 21/12/2013 11:16, Phil Allison wrote:
"Eiron"

You're not paying attention. It's an active design. Sensitivity doesn't
matter.


** It always matters.

For one reason, taken along with power rating, it sets the max available
SPL.

For another, with a given max drive power, it sets the available head room
( in dBs) for peaks

FYI:

the very low ( 80 dB/watt ) figure quoted for the KEF T27 is suspicious.

http://p10hifi.net/planet10/TLS/driv.../T27-dataS.gif

KEF were not quoting sensitivity the same way that is normally used today.

Thanks for that.
For those of us with classic speakers designed in the vinyl days,
you probably need to keep the volume down when playing modern CDs
with smiley equalization lest you blow the tweeters.

--
Eiron.

Tweeter choice
 

In article ,
Eiron wrote:
Thanks for that.
For those of us with classic speakers designed in the vinyl days,
you probably need to keep the volume down when playing modern CDs
with smiley equalization lest you blow the tweeters.

It's interesting that the Morel CAT 298 said to be a replacement for the
T27 has a DIN power rating of 80w, whereas the Audax TWO34XO with a larger
voice coil is rated at 70watt IEC. Not quite sure about the difference
between DIN and IEC. ;-) The Audax is 4dB more sensitive, though.

--
*If tennis elbow is painful, imagine suffering with tennis balls *

Dave Plowman London SW
To e-mail, change noise into sound.

Tweeter choice
 

"Don Pearce"
"Phil Allison"

"Eiron"

You're not paying attention. It's an active design. Sensitivity doesn't
matter.


** It always matters.

For one reason, taken along with power rating, it sets the max available
SPL.

For another, with a given max drive power, it sets the available head room
( in dBs) for peaks

FYI:

the very low ( 80 dB/watt ) figure quoted for the KEF T27 is suspicious.

http://p10hifi.net/planet10/TLS/driv.../T27-dataS.gif

KEF were not quoting sensitivity the same way that is normally used today.


I suspect that the low 80dB at 1 watt rating is due to pink noise
being specified.

** But what sort of "pink noise" ??

To paraphrase George Orwell, some kinds of pink noise are more equalised
than others.


1 watt of pink noise will have a great deal less than
1 watt of power in the tweeter band.

** For certain.

But what band did KEF's pink noise signal cover ??

Imagine 10 octave wide bands of pink noise covering the audio range centred
on 32, 64, 128, 250, 500, 1k, 2k, 4k, 8k & 16k then each will contain 10%
of the total power in the signal.

Take only the top four and you have 40% or -4dB.



..... Phil