[Ian Iveson]

A high fidelity valve amplifier should IMO

* have an output impedance of no more than one tenth of the
impedance of its load. This is an opinion I wish to pursue.

* properly load the output valve(s), so that a triode, for
example, should be loaded with at least 2.5 times it's anode
impedance. O.K., another rule of thumb, but I want to stick
to it.

Looking at available output transformers intended for
headphone amps, it is possible to make an amp for 70 ohm
phones that meets those criteria without using overall
negative feedback, but only just.

For example, there is a Sowter transformer offering 10k : 70
ohm. When driven as recommended, the resulting amplifier
provides a load for the driving cathode follower of 10k, and
has an output impedance of just under 7 ohms.

However, I want to drive Grado 'phones of 30 ohms. A little
calculation would reveal that the Sowter example above has
winding resistance, referred to the secondary, of about 4
ohms. It is possible that the same transformer with
secondary connected or wound for 30 ohms would just about
scrape home because the reflected primary resistance would
be reduced, but I doubt it.

I don't want to use a cathode follower either. If I use my
intended triode-connected 6CH6 with the transformer coupled
to the anode, as I prefer, I end up a few ohms too high.

Consequently, overall feedback seems a necessity. I don't
mind that per se, but it complicates the issue of soft
limiting.

I don't want to risk hurting my ears, so I want the output
stage to be limited. I want hi-fi up to a reasonable output
level, beyond which it should as gracefully as possible
compress any further excursion to within a safe limit. I
feel that this limiting should be done by the output stage
because that would protect me from signals generated by the
amp itself under fault conditions.

Feedback tends to harden limiting. If I arrange the output
stage to limit how I want it to, then feedback will make it
too sharp. If OTOH I make it so soft that it is right with
feedback, then the limit will introduce unwanted open-loop
distortion into the signal at a reasonable listening level.

Anyone got any ideas on how best to limit the output of my
headphone amp so I get max hi-fi without risking damaged
ears?

cheers, Ian

[Chris Hornbeck]

On Sun, 07 Oct 2007 02:21:51 GMT, "Ian Iveson"
wrote:

Anyone got any ideas on how best to limit the output of my
headphone amp so I get max hi-fi without risking damaged
ears?

Sounds like an interesting project. At what output voltage
should limiting begin? How soft do you wish the knee to be?
And, especially, how short an overload recovery time to
you require?

Thanks, as always,

Chris Hornbeck

[Phil Allison]

"Ian Iveson"

Anyone got any ideas on how best to limit the output of my headphone amp
so I get max hi-fi without risking damaged ears?


** Connect a small bulb ( say 6 volt @ 60 mA) is series with the 30 ohm
phones.

This will limit *steady* power in the phones to about 100mW ( 0.06 x 0.06 x
30) - which is close to ideal.

When there is enough steady power to light the bulb, then 100 ohms of
resistance appears in series with the 30 ohms headphones, attenuates the
power to a safe level PLUS the drive amp then sees a 130 ohms load.

Hence any clipping will be much softer.


........ Phil

[Ian Iveson]

Phil said

Anyone got any ideas on how best to limit the output of
my headphone amp so I get max hi-fi without risking
damaged ears?

** Connect a small bulb ( say 6 volt @ 60 mA) is series
with the 30 ohm phones.

This will limit *steady* power in the phones to about
100mW ( 0.06 x 0.06 x 30) - which is close to ideal.

When there is enough steady power to light the bulb, then
100 ohms of resistance appears in series with the 30 ohms
headphones, attenuates the power to a safe level PLUS
the drive amp then sees a 130 ohms load.

Hence any clipping will be much softer.

Genius.

I was thinking along the lines of an active series
resistance after the transformer rather than a shunt, so the
load is maintained
and recovery is less of an issue. Then I thought I should
add a shunt to maintain the load near 30 ohms...less
necessary but possibly desirable because of stability
issues.

Wondering also if the delay of a filament lamp is
appropriate. How long does it take to damage an ear?

I hope to illustrate of the emerging design by posting
schematics and simulations, so the results of ideas, good or
bad, can be demonstrated to everyone.

Anyone got a spice 3f4 filament lamp? The common Pspice
model has a component that cannot easily be translated.

Thanks, Ian

[Ian Iveson]

Chris said

Anyone got any ideas on how best to limit the output of my
headphone amp so I get max hi-fi without risking damaged
ears?

Sounds like an interesting project. At what output voltage
should limiting begin? How soft do you wish the knee to
be?
And, especially, how short an overload recovery time to
you require?

The Grados will hurt my ears at around 1.7Vrms. I would be
happy if they were clean up to, say, 1.5Vrms.

My notion of "hurt my ears" is very vague, but I felt that
would be another discussion. So for the moment I am
considering an absolute limit of 1.7V. Let's say the signal
should be unaffected at 1.5V.

In terms of power, that would be a clean 75mW, and an
absolute limit of 100mW

IIRC, European standards state 5V into 200 ohms in series
with the load, which would give about 110mW, so we would be
in the correct stadium.

Those with a knowledge of pro audio standards can probably
help with a more sophisticated concept of limiting. Simple
clipping is crude.

Recovery time at this stage of my thinking should be
somewhere in the region of short.

I'll post a test circuit and graphical analysis soon. Noise
would be hard to simulate, but other stuff such as Bode
diagrams and Fourier analysis will be straightforward.

cheers, Ian

[Eeyore]

Ian Iveson wrote:

IIRC, European standards state 5V into 200 ohms in series
with the load

And where do they say this ?

Graham

[Eeyore]

Ian Iveson wrote:

Those with a knowledge of pro audio standards can probably
help with a more sophisticated concept of limiting. Simple
clipping is crude.

It's the CLIPPING that HURTS you nitwit.

Graham

[Rudy]

"Eeyore" wrote in message
...
:
:
: Ian Iveson wrote:
:
: Those with a knowledge of pro audio standards can probably
: help with a more sophisticated concept of limiting. Simple
: clipping is crude.
:
: It's the CLIPPING that HURTS you nitwit.
:
: Graham
:
Graham, Graham.
Never short of an insult to make, some derision to post,
I keep hearing Sgt. Oddball (Donald Sutherland) in Kelly's Heroes saying:
"there you go again, with your negative feelings. the bridge *will* be
there"
when i read (a substantial part of) your posts.
heh
just compare your 'contribution' above to say, Phil's excellent idea of
using a low power light bulb in this thread - whaddare you trying to
accomplish - thread erosion ?

Recent example on RAT:
the Linsley Hood ss amp, where after repeatedly qualifying it as nothing
like what can be done nowadays, the logical follow up question : what do you
think is an example of such an amplifier design, you get all enthousiastic
about
a design of your own
but sadly refrain from telling anything about that amp !

If you are (were) a professional designer of audio equipment
i find it hard to believe that one-liners is all you can up with in a design
newsgroup!

what about some substance, eh ?
besides, if you must continue your 'ways', at least be somewhat more
creative
doin' it :-))

Rudy

[Ian Iveson]

Graham said

IIRC, European standards state 5V into 200 ohms in
series
with the load

And where do they say this ?

Perhaps you could help by looking it up? The standard is EN
50332-1:2000, I think.

I have seen several quite different interpretations.

Meanwhile, you missed a seriously misleading bit of
arithmetic he

"which would give about 110mW".

Wake up.

Ian

[Ian Iveson]

A couple of informative links:

http://www.headwize.com/articles/hearing_art.htm

http://www.canford.co.uk/Techzone/EarphoneLimiters.pdf

The BBC limiters look interesting. As with Phil's idea, they
are placed between the headphone output and the phones.
Anyone know what's in them?

Ian

[Eeyore]

Rudy wrote:

"Eeyore" wrote
: Ian Iveson wrote:
:
: Those with a knowledge of pro audio standards can probably
: help with a more sophisticated concept of limiting. Simple
: clipping is crude.
:
: It's the CLIPPING that HURTS you nitwit.
:
: Graham
:
Graham, Graham.
Never short of an insult to make, some derision to post,
I keep hearing Sgt. Oddball (Donald Sutherland) in Kelly's Heroes saying:
"there you go again, with your negative feelings. the bridge *will* be
there"
when i read (a substantial part of) your posts.

Unfortunately Iveson is reliably wrong about almost everthing he posts and my
patience with such stupidity is limited.

Graham

[Eeyore]

Ian Iveson wrote:

Graham said

IIRC, European standards state 5V into 200 ohms in
series with the load

And where do they say this ?

Perhaps you could help by looking it up? The standard is EN
50332-1:2000, I think.

I have seen several quite different interpretations.

Meanwhile, you missed a seriously misleading bit of
arithmetic he

"which would give about 110mW".

Wake up.

It was so vague I didn't even bother thinking about it.

A typical modern headphone is 32 ohms. It seems to be a standard of sorts. In
series with 200 ohms, and driven from 5V that would result in 21.5 mA.

21.5mA in 32 ohms is about 15 mW. Moot anyway since widely different
efficiencies make direct comparisons of power input largely pointless.

Graham

[Eeyore]

Ian Iveson wrote:

Graham said

IIRC, European standards state 5V into 200 ohms in
series with the load

And where do they say this ?

Perhaps you could help by looking it up? The standard is EN
50332-1:2000, I think.

Apparently so.

Do you fany ponying up the required £52 ?
http://www.standardsdirect.org/stand...iew_14535.html

Graham

[Ian Iveson]

Graham said:

IIRC, European standards state 5V into 200 ohms in
series with the load

And where do they say this ?

Perhaps you could help by looking it up? The standard is
EN
50332-1:2000, I think.

I have seen several quite different interpretations.

Meanwhile, you missed a seriously misleading bit of
arithmetic he

"which would give about 110mW".

Wake up.

It was so vague I didn't even bother thinking about it.

A typical modern headphone is 32 ohms. It seems to be a
standard of sorts. In
series with 200 ohms, and driven from 5V that would result
in 21.5 mA.

I stated 30 ohms

21.5mA in 32 ohms is about 15 mW.

Good. I included the power wasted by the resistor...

Moot anyway since widely different
efficiencies make direct comparisons of power input
largely pointless.

Can you substantiate that, please?

My impression is that the opposite is true: that impedance
varies widely but efficiency is broadly similar for ordinary
good-quality headphones. Something around 100mW seems to be
regarded as a reasonable power limit.

Ian

[Ian Iveson]

Graham:

21.5mA in 32 ohms is about 15 mW.

Good. I included the power wasted by the resistor...

You may not find my meaning obvious...I mean wasted by the
source resistance.

Ian

[Eeyore]

Ian Iveson wrote:

Graham said:

Moot anyway since widely different
efficiencies make direct comparisons of power input
largely pointless.

Can you substantiate that, please?

My impression is that the opposite is true: that impedance
varies widely but efficiency is broadly similar for ordinary
good-quality headphones. Something around 100mW seems to be
regarded as a reasonable power limit.

Moving coil headphones are no different in their principle of operation to
moving coil loudspeakers which are widely known to have sensitivities as much as
20dB different.

I don't feel inclined to do your legwork but I happened across something last
week which suggested figures 10dB apart from different headphones in the same
manufacturer's range. It was Beyer IIRC.

Graham

[Ian Iveson]

Graham said:

Moot anyway since widely different
efficiencies make direct comparisons of power input
largely pointless.

Can you substantiate that, please?

My impression is that the opposite is true: that
impedance
varies widely but efficiency is broadly similar for
ordinary
good-quality headphones. Something around 100mW seems to
be
regarded as a reasonable power limit.

Moving coil headphones are no different in their principle
of operation to
moving coil loudspeakers which are widely known to have
sensitivities as much as
20dB different.

Perhaps you missed the words "broadly" and "ordinary"

Ordinary loudspeakers don't differ by as much as 20dB.
Nowhere near.

The mode for domestic speakers is in the high 80s, with most
falling within a few dB.

I don't feel inclined to do your legwork

OK...whatever...it's just that you gave the impression you
already know something. Hence I foolishly assumed you had
done the "legwork".

but I happened across something last
week which suggested figures 10dB apart from different
headphones in the same
manufacturer's range. It was Beyer IIRC.

So that's what "legwork" is. But that's a very poor
sampling method. Perhaps if you weighted according to sales
to the domestic market, and then found the mode and standard
deviation? Better, I suggest, would be to find the top
sellers regardless of manufacturer.

Ian

[terryS]

On Oct 7, 12:21 am, "Ian Iveson"
wrote:
A high fidelity valve amplifier should IMO

* have an output impedance of no more than one tenth of the
impedance of its load. This is an opinion I wish to pursue.

* properly load the output valve(s), so that a triode, for
example, should be loaded with at least 2.5 times it's anode
impedance. O.K., another rule of thumb, but I want to stick
to it.

Looking at available output transformers intended for
headphone amps, it is possible to make an amp for 70 ohm
phones that meets those criteria without using overall
negative feedback, but only just.

For example, there is a Sowter transformer offering 10k : 70
ohm. When driven as recommended, the resulting amplifier
provides a load for the driving cathode follower of 10k, and
has an output impedance of just under 7 ohms.

However, I want to drive Grado 'phones of 30 ohms. A little
calculation would reveal that the Sowter example above has
winding resistance, referred to the secondary, of about 4
ohms. It is possible that the same transformer with
secondary connected or wound for 30 ohms would just about
scrape home because the reflected primary resistance would
be reduced, but I doubt it.

I don't want to use a cathode follower either. If I use my
intended triode-connected 6CH6 with the transformer coupled
to the anode, as I prefer, I end up a few ohms too high.

Consequently, overall feedback seems a necessity. I don't
mind that per se, but it complicates the issue of soft
limiting.

I don't want to risk hurting my ears, so I want the output
stage to be limited. I want hi-fi up to a reasonable output
level, beyond which it should as gracefully as possible
compress any further excursion to within a safe limit. I
feel that this limiting should be done by the output stage
because that would protect me from signals generated by the
amp itself under fault conditions.

Feedback tends to harden limiting. If I arrange the output
stage to limit how I want it to, then feedback will make it
too sharp. If OTOH I make it so soft that it is right with
feedback, then the limit will introduce unwanted open-loop
distortion into the signal at a reasonable listening level.

Anyone got any ideas on how best to limit the output of my
headphone amp so I get max hi-fi without risking damaged
ears?

cheers, Ian

As a complete newcomer to this audio business!
And not quite sure what is meant by 'limit'? Assuming it is not some
'active' circuit that cuts in or cuts off peaks of audio;
it becomes s a matter of proper matching?
You mention that you prefer plate coupling not cathode follower. I'd
like to ask a question about CF in separate thread.
But it appears that you wish to reflect the correct impedance back
into the plate of the OP tube's with 30 ohm phones intead of 7 0hm
speakers?
Is it not possible to shunt the phones with some resistance. Pure non
reactive resistance in parallel withe phones.
Shunting with 30 ohms will immediately halve the impedance reflected
back through the OP transformer/s to the plate circuit/s? Assuming
stereo!
Shunting with 10 ohms will provide an approx. 7.5 ohm load!
But as said as a newbie to audio amps. etc. stand to be corrected.
Presumably we are talking millwatts of power here; even 5 volts across
30 ohms is less than a watt (peak)?
A 10 ohm resistor will dissipate approx. 3 times the audio power that
is turned into sound by the headphones? Couple of watts,
intermittent?
BTW don't pentodes and tetrodes have higher plate load? If soi could
the same transformer be used with the OP tube (the 6CH6 mentioned for
example) configured that way instead of triode connected?
Flame/blast away; willing to learn!

[christofire]

"Ian Iveson" wrote in message
.uk...
A couple of informative links:

http://www.headwize.com/articles/hearing_art.htm

http://www.canford.co.uk/Techzone/EarphoneLimiters.pdf

The BBC limiters look interesting. As with Phil's idea, they are placed
between the headphone output and the phones. Anyone know what's in them?

Ian

Probably amplifier/rectifier, with some kind of frequency and time weighting
networks built-in, driving FETs in an (L-configuration?) attenuator, all
powered by the incoming audio signal. Perhaps not ideal for protecting the
wearer from plugging in to a hot source, or maybe the attenuator defaults to
many dB - that would be sensible but I don't remember any significant delay
in practice.

Canford took on the supply function from BBC Equipment Department many years
ago so they would know.

Chris

[Phil Allison]

"Eeysore Congenital Pommy ******" "
Ian Iveson wrote:


My impression is that the opposite is true: that impedance
varies widely but efficiency is broadly similar for ordinary
good-quality headphones. Something around 100mW seems to be
regarded as a reasonable power limit.

Moving coil headphones are no different in their principle of operation to
moving coil loudspeakers


** WRONG.

Headphones operate very much like microphones - note how the top
performing models are typically made by *microphone* makes or specialist
headphone makers. Not speaker makers.


which are widely known to have sensitivities as much as 20dB different.


** Totally FALSE analogy.

Unlike speakers, dynamic headphones do not vary widely in size ( all gotta
fit a human head) or basic construction techniques.


I don't feel inclined to do your legwork but I happened across something
last
week which suggested figures 10dB apart from different headphones in the
same
manufacturer's range. It was Beyer IIRC.


** The vast majority of modern, dynamic headphones have quoted dB/mW
figures around 95 - 102dB SPL - means they will play VERY LOUD with 50
to 100 mW of input power.

Analogies with speakers that must fill some arbitrary size room with loud
sound are ENTIRELY FALSE.



....... Phil

[Chris Hornbeck]

On Mon, 08 Oct 2007 01:30:06 GMT, "Ian Iveson"
wrote:

Anyone got any ideas on how best to limit the output of my
headphone amp so I get max hi-fi without risking damaged
ears?

Sounds like an interesting project. At what output voltage
should limiting begin? How soft do you wish the knee to
be?
And, especially, how short an overload recovery time to
you require?

The Grados will hurt my ears at around 1.7Vrms. I would be
happy if they were clean up to, say, 1.5Vrms.

My notion of "hurt my ears" is very vague, but I felt that
would be another discussion. So for the moment I am
considering an absolute limit of 1.7V. Let's say the signal
should be unaffected at 1.5V.

Do you know the headphones' rated sensitivity? Hurting your
ears is a dangerously high level and way beyond the damage
level. I'd very strongly recommend that your limiter allow
a maximum VU of 85dB SPL and/or a maximum peak level of
105dB SPL.

Those with a knowledge of pro audio standards can probably
help with a more sophisticated concept of limiting. Simple
clipping is crude.

Recovery time at this stage of my thinking should be
somewhere in the region of short.

Right. A good limiter has a fast risetime and a slow (in
this case maybe 1/4 sec) decay time. Incandescent lamps
as used to protect tweeters in sound reinforcement are
not appropriate in any way.

Limiters may be made with either feedback or as a parallel
"side channel", in either case with a variable resistance
device in the upstream signal path. The variable resistance
is driven by a little circuit with rectifier, (sometimes
adjustable) time constants, and a "law", that is, a bent
(and usually adjustably bendable) curve between input and
output voltages.

Personally, I might consider including a little light to
indicate operation. Headphones are so clean that too-high
volumes are common. But still damaging, so seeing the threshold
achieved is important information.

Thanks, as always,

Chris Hornbeck

[Eeyore]

Ian Iveson wrote:

Graham said:


Moving coil headphones are no different in their principle
of operation to moving coil loudspeakers which are widely known to have
sensitivities as much as 20dB different.

Perhaps you missed the words "broadly" and "ordinary"

Ordinary loudspeakers don't differ by as much as 20dB.
Nowhere near.

MORON.

http://www.google.com/search?q=83db%2Fw
http://www.google.com/search?q=103db%2Fw

Covers the 20dB range.

Graham

[Eeyore]

flipper wrote:

I don't know what the point to this thread is, nor do I care, because
everyone seems mainly interested in throwing 'you're stupid' insults
back and forth

Iveson IS stupid.

He's incapable of making a post without making at least one serious error of
fact.

Graham

[Eeyore]

Chris Hornbeck wrote:

I'd very strongly recommend that your limiter allow
a maximum VU of 85dB SPL

VU again ? Do you mean 'volume' ?


and/or a maximum peak level of 105dB SPL.

20dB difference betwen peak and average levels ? For orchestral maybe.

An average SPL of 85dB is absolutely of no concern at all from the perspective
of hearing damage. Also, applying industrial noise standards to music is highly
inappropriate.

Graham

[Eeyore]

Phil Allison wrote:

"Eeysore Congenital Pommy ******" "
Ian Iveson wrote:

My impression is that the opposite is true: that impedance
varies widely but efficiency is broadly similar for ordinary
good-quality headphones. Something around 100mW seems to be
regarded as a reasonable power limit.

Moving coil headphones are no different in their principle of operation to
moving coil loudspeakers

** WRONG.

Headphones operate very much like microphones - note how the top
performing models are typically made by *microphone* makes or specialist
headphone makers. Not speaker makers.

So damn what ? All of them have moving coils !

Jesus wept.

Graham

[Chris Hornbeck]

On Tue, 09 Oct 2007 01:09:12 +0100, Eeyore
wrote:

I'd very strongly recommend that your limiter allow
a maximum VU of 85dB SPL

VU again ? Do you mean 'volume' ?

I should have said "0VU" to be clear to all.

and/or a maximum peak level of 105dB SPL.

20dB difference betwen peak and average levels ? For orchestral maybe.

Perzactly.

An average SPL of 85dB is absolutely of no concern at all from the perspective
of hearing damage. Also, applying industrial noise standards to music is highly
inappropriate.

Hearing damage shouldn't be trivialized with polemics.

And, threshold of limiting might be chosen to operate from
either an averaged and/or a peak level.

So, what do *you* recommend?

Thanks, as always,

Chris Hornbeck

[Eeyore]

Phil Allison wrote:

** The vast majority of modern, dynamic headphones have quoted dB/mW
figures around 95 - 102dB SPL

You have chosen to arbitrarily introduce 'modern' I see. Even so, my *MODERN*
DT331s have only 86dB sensitivity. Whereas a *MODERN* DT411 has 102 dB
sensitivity. In excess in fact of the 10dB variation I referred to with Beyer
headphones.


- means they will play VERY LOUD with 50
to 100 mW of input power.

The sensitivities shown here (the second column) vary from 84 to 106dB/mW.
http://www.rane.com/hc6hp.html

IDIOT !

Now bow to my superior knowledge you antipodean nitwit.

Graham


Manufacturer Model Impedance
(Ohms) Sensitivity
(dB) Max Power
(mW) Max SPL
(dB)
AKG K141M 600 98 80 117
K240M, K240DF 600 88 80 107
K270S 75 92 380 118
K301 100 94 285 119
K401, K501 120 94 290 119
Audio-Technica ATH-COM1, COM2, ATH-908 40 90 440 116
ATH-910 40 92 440 118
ATH-P5 40 100 440 126
ATH-M40 60 100 400 126
ATH-D40 66 102 295 127
ATH-M2X, ATH-M3X 45 100 435 126
Beyerdynamic DT150 250 97 175 119
DT211, DT311 40 98 440 124
DT250 80 98 360 123
DT411 250 102 175 124
DT531 250 95 175 116
DT431, DT331 40 86 440 112
DT770PRO, DT990PRO 600 96 80 115
DT801, DT811, DT511 250 94 175 116
DT901, DT911 250 98 175 120
Fostex T-5 44 96 435 122
T-7 70 98 385 124
T-20 50 96 425 122
T-40 50 98 425 124
Hosa HDS-701 40 91 440 117
Koss A/250, A/200, A/130, TD/80 60 98 320 125
R/200 60 84 400 110
R/100, R/45 60 85 400 111
R/90, HD/2, SB/15 60 100 400 126
R/80, R/35S, R/20, Porta Pro models 60 101 400 127
R/70B, R/55B, SB/50, SB/35 60 101 400 127
R/40 60 90 400 116
R/30S 60 106 400 132
R/10 60 103 400 129
TD/75 60 95 400 121
TD/65 90 101 340 126
TD/61 38 93 440 119
Sennheiser HD433, HD435 32 94 450 121
HD25 70 120 380 146
HD445 52 97 390 123
HD25SP 85 100 350 125
HD265, HD525, HD535, HD545, HD565 150 94 190 117
HD455, HD475 60 94 400 120
HD465 100 94 285 119
HD580, HD600 300 97 80 116
Sony MDR-V100MK2 32 98 450 125
MDR-85 40 102 440 128
MDR-V600, MDR-D77 45 106 435 132
MDR-CD10 32 96 450 123
MDR-CD550, CD750 45 100 435 126
MDR-CD6 45 110 435 136
MDR-CD850, CD950 32 102 450 129
MDR-CD1000, CD3000 32 104 450 131
MDR-D33, MDR-D55, MDR-7504 45 104 435 130
MDR-7506 63 106 400 132
MDR-7502 45 102 435 128
Stanton ST PRO, DJ PRO 1000 32 100 450 127
Telex PH-6 600 105 80 124
Yamaha RH5M 32 98 450 125
RH1 32 90 450 116
RH2 32 95 450 122
RH3 60 95 400 121
RH10M 40 102 440 128
RH40M 32 103 450 130

[Eeyore]

Ian Iveson wrote:

Graham said:

but I happened across something last
week which suggested figures 10dB apart from different
headphones in the same
manufacturer's range. It was Beyer IIRC.

So that's what "legwork" is. But that's a very poor
sampling method. Perhaps if you weighted according to sales
to the domestic market, and then found the mode and standard
deviation? Better, I suggest, would be to find the top
sellers regardless of manufacturer.

Look here you lazy ****, I pointed you in the direction of Beyer but you
couldn't be bothered to get off you lazy ignorant ass to check.

http://www.rane.com/hc6hp.html

Manufacturer Model Impedance (Ohms)
Sensitivity (dB)
Max Power (mW)
Max SPL (dB)

Beyerdynamic
DT150 250 97 175 119
DT211, DT311 40 98 440 124
DT250 80 98 360 123
DT411 250 102 175 124
DT531 250 95 175 116
DT431, DT331 40 86 440 112
DT770PRO, DT990PRO 600 96 80 115
DT801, DT811, DT511 250 94 175 116
DT901, DT911 250 98 175 120

Graham

[Chris Hornbeck]

On Tue, 09 Oct 2007 02:06:03 +0100, Eeyore
wrote:

Manufacturer Model Impedance
(Ohms) Sensitivity
(dB) Max Power
(mW) Max SPL
(dB)

The chart doesn't scan in a fixed-pitch font, but the thrust
is clear enough. Only referencing limiting threshold levels to
SPL is even remotely useful.

Thanks, as always,

Chris Hornbeck

[Eeyore]

Chris Hornbeck wrote:

On Tue, 09 Oct 2007 01:09:12 +0100, Eeyore
wrote:

I'd very strongly recommend that your limiter allow
a maximum VU of 85dB SPL

VU again ? Do you mean 'volume' ?

I should have said "0VU" to be clear to all.

and/or a maximum peak level of 105dB SPL.

20dB difference betwen peak and average levels ? For orchestral maybe.

Perzactly.

An average SPL of 85dB is absolutely of no concern at all from the perspective
of hearing damage. Also, applying industrial noise standards to music is highly
inappropriate.

Hearing damage shouldn't be trivialized with polemics.

There's nothing polemic about it.


And, threshold of limiting might be chosen to operate from
either an averaged and/or a peak level.

So, what do *you* recommend?

Fretting over an average SPL of 85 dB is excessive. That's a figure suggested for
exposure to industrial noise 8 hours a day. The point being that industrial noise
contains a lot of high intensity impulsive noise which is what largely does the
damage and music doesn't contain nearly as much of that.

Mind you, if you *are* exposed to 85dB of industrial noise 8 hours a day you
shouldn't THEN listen to loud music as well. Given that few workers in the west work
in steel mills and the like any more and most of us work in offices, we needn't fret
over our our work related exposure however..

Using the HSE's chart for 2 hours exposure
http://www.hse.gov.uk/noise/dailyexposure.pdf
you'd be good for 91dB of industrial noise. I personally certainly wouldn't fret
over 95dB of music, which could mean peaks of up to 115dB. I doubt that 100/120dB
would do you any harm either.

Graham

[Eeyore]

Chris Hornbeck wrote:

Eeyore wrote:

I'd very strongly recommend that your limiter allow
a maximum VU of 85dB SPL

VU again ? Do you mean 'volume' ?

I should have said "0VU" to be clear to all.

"0VU" is a voltage. 1.228V rms to be precise.

Why do you preversely insist on continuing to use this daft measuement for SPL ?

Where will you find any hi-fi amplifier with a VU meter today even ?

Graham

[Chris Hornbeck]

On Tue, 09 Oct 2007 02:33:33 +0100, Eeyore
wrote:

Fretting over an average SPL of 85 dB is excessive. That's a figure suggested for
exposure to industrial noise 8 hours a day. The point being that industrial noise
contains a lot of high intensity impulsive noise which is what largely does the
damage and music doesn't contain nearly as much of that.

Mind you, if you *are* exposed to 85dB of industrial noise 8 hours a day you
shouldn't THEN listen to loud music as well. Given that few workers in the west work
in steel mills and the like any more and most of us work in offices, we needn't fret
over our our work related exposure however..

Using the HSE's chart for 2 hours exposure
http://www.hse.gov.uk/noise/dailyexposure.pdf
you'd be good for 91dB of industrial noise. I personally certainly wouldn't fret
over 95dB of music, which could mean peaks of up to 115dB. I doubt that 100/120dB
would do you any harm either.

Thanks for your comments.

Personally, 85dB SPL is starting to feel painful. But I'm
increasingly conservative as I get older (ref: Winston Churchill)
and also tend to generically discount all government/industrial-
approved safety standards (ref: Dwight Eisenhower).

I need my hearing for both work and real life. So I'll
continue to be conservative. Others must make their own
decisions for themselves.

Thanks, as always,

Chris Hornbeck

[Chris Hornbeck]

On Tue, 09 Oct 2007 02:37:56 +0100, Eeyore
wrote:

VU again ? Do you mean 'volume' ?

I should have said "0VU" to be clear to all.

"0VU" is a voltage. 1.228V rms to be precise.

0VU is an arbitrary level to be defined in context. Please
don't pretend that you don't understand something so deeply
ingrained in professional audio; it's disingenuous.

0dBu is 1.228 volts, measured in a particular way. As you
know very well.

Jesus KeRist KeRumpus, Mon,

Chris Hornbeck

[Eeyore]

Chris Hornbeck wrote:

Eeyore wrote:

VU again ? Do you mean 'volume' ?

I should have said "0VU" to be clear to all.

"0VU" is a voltage. 1.228V rms to be precise.

0VU is an arbitrary level to be defined in context.

Not in my experience.


Please
don't pretend that you don't understand something so deeply
ingrained in professional audio; it's disingenuous.

0dBu is 1.228 volts, measured in a particular way. As you
know very well.

It's the only example I know of its use.

For all other purposes your use of the term is only confusing I beg to suggest.
Another form of words would be far more understandable.

Graham

[Chris Hornbeck]

On Tue, 09 Oct 2007 03:16:04 +0100, Eeyore
wrote:

0dBu is 1.228 volts, measured in a particular way. As you
know very well.

It's the only example I know of its use.

For all other purposes your use of the term is only confusing I beg to suggest.
Another form of words would be far more understandable.

But 0dBu is *actually* .775 volts.

And 0VU in a professional audio context is actually +4dBu,
IOW, 1.228 volts. So you're caught; you actually *do*
understand the actual meaning and are just ****ing with me.

Not cute, I expect better of you,

Chris Hornbeck

[Phil Allison]

"Eeysore Congenital Pommy ******"

Ian Iveson wrote:

My impression is that the opposite is true: that impedance
varies widely but efficiency is broadly similar for ordinary
good-quality headphones. Something around 100mW seems to be
regarded as a reasonable power limit.

Moving coil headphones are no different in their principle of operation
to
moving coil loudspeakers

** WRONG.

Headphones operate very much like microphones - note how the top
performing models are typically made by *microphone* makes or specialist
headphone makers. Not speaker makers.

So damn what ? All of them have moving coils !


** Unlike speakers, dynamic headphones do not vary widely in size ( all
gotta
fit a human head) or basic construction techniques.

Like microphones and for similar reasons of restricted size range, the
sensitivity figures do not vary widely.




........ Phil

[Phil Allison]

"Eeysore Congenital ****ing MORON "


** The vast majority of modern, dynamic headphones have quoted dB/mW
figures around 95 - 102dB SPL

You have chosen to arbitrarily introduce 'modern' I see. Even so, my
*MODERN*
DT331s have only 86dB sensitivity. Whereas a *MODERN* DT411 has 102 dB
sensitivity. In excess in fact of the 10dB variation I referred to with
Beyer
headphones.


The sensitivities shown here (the second column) vary from 84 to 106dB/mW.
http://www.rane.com/hc6hp.html


** Remove the few extreme examples plus plus very old and obsolete models

= VAST MAJORITY inside the range I quoted.


You asinine, non reading prick.



........ Phil

[Eeyore]

Chris Hornbeck wrote:

On Tue, 09 Oct 2007 03:16:04 +0100, Eeyore
wrote:

0dBu is 1.228 volts, measured in a particular way. As you
know very well.

It's the only example I know of its use.

For all other purposes your use of the term is only confusing I beg to suggest.
Another form of words would be far more understandable.

But 0dBu is *actually* .775 volts.

I assumed you meant 0VU when you posted that. I probably read it as that without
even thinking about it.


And 0VU in a professional audio context is actually +4dBu,
IOW, 1.228 volts. So you're caught; you actually *do*
understand the actual meaning and are just ****ing with me.

Not cute, I expect better of you,

Eh ?

It was YOUR mistake, and I missed it, reading it as I imagine you intended it to be
read as "0VU".

Why are having ago at me ? For not spotting your mistake ?

"Not cute, I expect better of you "

Graham

[Eeyore]

Phil Allison wrote:

"Eeyore"
Ian Iveson wrote:

My impression is that the opposite is true: that impedance
varies widely but efficiency is broadly similar for ordinary
good-quality headphones. Something around 100mW seems to be
regarded as a reasonable power limit.

Moving coil headphones are no different in their principle of operation
to moving coil loudspeakers

** WRONG.

CORRECT !


Headphones operate very much like microphones - note how the top
performing models are typically made by *microphone* makes or specialist
headphone makers. Not speaker makers.

So damn what ? All of them have moving coils !

** Unlike speakers, dynamic headphones do not vary widely in size ( all
gotta fit a human head) or basic construction techniques.

Like microphones and for similar reasons of restricted size range, the
sensitivity figures do not vary widely.

ONLY BY **** TWENTY TWO **** dB !
http://www.rane.com/hc6hp.html

Graham

[Eeyore]

Phil Allison wrote:

"Eeyore"

** The vast majority of modern, dynamic headphones have quoted dB/mW
figures around 95 - 102dB SPL

You have chosen to arbitrarily introduce 'modern' I see. Even so, my
*MODERN*
DT331s have only 86dB sensitivity. Whereas a *MODERN* DT411 has 102 dB
sensitivity. In excess in fact of the 10dB variation I referred to with
Beyer headphones.


The sensitivities shown here (the second column) vary from 84 to 106dB/mW.
http://www.rane.com/hc6hp.html

** Remove the few extreme examples plus plus very old and obsolete models

= VAST MAJORITY inside the range I quoted.

I have a DT331 here. A very popular model. It has 86 dB sensitivity. Nothing old
or obsolete about it at all.

STOP LYING !!!

Graham