searching better alternative for LM386

[Tom]

Martin,

have a look at the LT1010 from linear

Thank you, that looks like an interesting part. Its ~8 ohm output
resistance is on the high side for a 10 ohm load, but if it stays
sufficiently constant I can compensate for that. It swings to within 3V
from the rails, which is also OK (this is less relevant for the 10 ohm
headphones but important for 50-ohm impedance bone-stimulating
actuators which could also be used instead). The +-150mA current limit
should also be just enough to meet my specs. I'll try to get my hands
on some of these parts to try them out...

greetings,
Tom

 

[Eeyore]

Everyone,

In my design I need to drive headphones with nominally 10 ohm impedance
with an audio signal. The supply for the audio is +12V single supply
(this is created from the main 2.5V-3.3V battery supply using a DC/DC
converter). The output swing does not need to be all the way to the
rail, something like 7..8V peak-peak is acceptable. The input signal is
0..2.5V.

The LM386 is a true POS !

I'd suggest you look at power amplifiers designed for car audio use. I'm sure
Philips (NXP) will have some in the TDA range.

Graham

 

[Phil Allison]

"Tom"

These are special in-ear phones for use in a medical setting to use
diagnosing the balance organs in your ear. The low impedance allows
high short-time power levels with a relatively low supply voltage
(12V).


I never said I would apply a constant sine wave with this power. Just a
short toneburst of, for example, 5 cycles long, once every 200
milliseconds or so.


Yes I have. I NEED to generate something in the order of 150 dB SPL
briefly during these tonebursts (at the maximum power setting,
obviously in most cases (healthy people etc.) the required power will
be much lower).

** Seems like an ** EXTRAORDINARILY ** dangerous thing for anyone to do.

One small, technical stuff up - the subject has their hearing permanently
damaged.

Might as well be firing gun shots right next to their ears !!

I am designing an application to specifications from the medical
doctors here.

** But YOU have already demonstrated YOU have NO damn idea what you are
doing.

Tell me - are any of those alleged " doctors " related to Joseph Mengele
by any chance ??

Please don't jump to conclusions about my criminal
intentions are stupidity without knowing anything about my application.

** The OBLIGATION is on * YOU * to inform us about your so called
"application".

It would be *criminal* for anyone reading your post to attempt to emulate
what you describe and are asking us about.

You completely forget this is OPEN PUBLIC FORUM - plus, all the posts
are archived by Google and others for decades.

This is ABSOLUTELY NOT the place to discuss dangerous experiments on
humans.


I absolutely stand by my earlier comments and the heading.
------------------------------------------------------------------


Someone FAR FAR more technically competent and wise than *YOU* needs to be
given the task.

The audio driving circuits to those earpieces MUST have safety interlocks
desigjed in and 100% fool proof automatic trips if input power levels
EVER exceed what is known to cause hearing damage .




........ Phil

 

[Phil Allison]

"Terry Given"


** **** off - you ASD fucked IDIOT !!





......... Phil

 

[martin griffith]

Martin,


Thank you, that looks like an interesting part. Its ~8 ohm output
resistance is on the high side for a 10 ohm load, but if it stays
sufficiently constant I can compensate for that. It swings to within 3V
from the rails, which is also OK (this is less relevant for the 10 ohm
headphones but important for 50-ohm impedance bone-stimulating
actuators which could also be used instead). The +-150mA current limit
should also be just enough to meet my specs. I'll try to get my hands
on some of these parts to try them out...

greetings,
Tom

thats why I suggested the "discrete version", cheaper, and you can
choose your own o/p transistors, emitter Rs , magic smoke level (tm),
etc.
I think TI and Analog do equivalents


martin

 

[Tom]

John,

I think you may have jumped to an invalid conclusion. I
would say that the noise you hear is passing through the
LM386, but not necessarily being generated by it. Have you
done a listen using a battery as a power supply?

Yes, I have provided the 12V from a battery (with short, twisted leads)
instead of from the DC/DC converter and the noise remains the same.

(if the 12V from the DC/DC is insufficiently filtered there is
additional noise in addition to this ever-present noise, but is caused
by the switching in the DC/DC converter, and is not white at all)

So I'm pretty sure it is the LM386 generating the noise. I can also
measure with the scope that the supplies are clean and the output has
significant noise, even if loaded with only 100 ohms instead of 10
ohms.

greetings,
Tom

 

[MassiveProng]

Phil,


These are special in-ear phones for use in a medical setting to use
diagnosing the balance organs in your ear. The low impedance allows
high short-time power levels with a relatively low supply voltage
(12V).


I never said I would apply a constant sine wave with this power. Just a
short toneburst of, for example, 5 cycles long, once every 200
milliseconds or so.


Yes I have. I NEED to generate something in the order of 150 dB SPL
briefly during these tonebursts (at the maximum power setting,
obviously in most cases (healthy people etc.) the required power will
be much lower).

I am designing an application to specifications from the medical
doctors here. Please don't jump to conclusions about my criminal
intentions are stupidity without knowing anything about my application.

The PhilTard is an engineer wanna be troll.

 

[Tim Shoppa]

In my design I need to drive headphones with nominally 10 ohm impedance
with an audio signal. The supply for the audio is +12V single supply
(this is created from the main 2.5V-3.3V battery supply using a DC/DC
...
So, basically I'm looking for a better audio amp, similar to the LM386
but with lower noise.

Classic answer for "more power than a LM386" is a LM383, but there's
ZERO reason for putting this much power into headphones.

LM4881 is very worthwhile as a headphone amp, plenty of power, much
less noise than a LM386.

Tim.

 

[Phil Allison]

"Tim Shoppa"

Classic answer for "more power than a LM386" is a LM383, but there's
ZERO reason for putting this much power into headphones.

** The OP is playing a VERY dangerous game with innocent people as potential
victims.

Seems he is a "digital" dude with **** all comprehension of analogue or
audio design.

He also has demonstrated **** all common sense or basic honesty.

Goes with the territory - IME.




........ Phil

 

[Jan Panteltje]

"Tim Shoppa"




** The OP is playing a VERY dangerous game with innocent people as potential
victims.

Seems he is a "digital" dude with **** all comprehension of analogue or
audio design.

He also has demonstrated **** all common sense or basic honesty.

Goes with the territory - IME.

In that case lemme propose a 2 x EL34 tube amp.

 

[Tom]

Tim,

Classic answer for "more power than a LM386" is a LM383,

I didn't ask for "more power than an LM386", I asked for lower noise.

but there's ZERO reason for putting this much power into headphones.

As I clarified in my later post to Phil the high power pulses are only
for very brief periods of time.

The audio power level given to the patients is decided by the doctors,
not by me. My device just has to able to support the specified maximum
range: 105 dB nHL, which corresponds to something on the order of 140
dB RMS SPL, depending on frequency and toneburst shape.

Currently they are doing the same thing with big wall-powered devices,
I'm merely implementing the same functionality (with the same
specifications) in a portable battery-powered design.

LM4881 is very worthwhile as a headphone amp, plenty of power, much
less noise than a LM386.

Thanks for the suggestion, I'll look into it.

greetings,
Tom

 

[Tom]

Jan,

In that case lemme propose a 2 x EL34 tube amp.

Cute, thanks, but doesn't quite meet the compactness & low power
requirements...

greetings,
Tom

 

[ian field]

Yeah. Yours should read:

Dickless Retard!

You two are just made for each other.

 

[ian field]

Tim,



I didn't ask for "more power than an LM386", I asked for lower noise.


As I clarified in my later post to Phil the high power pulses are only
for very brief periods of time.

The audio power level given to the patients is decided by the doctors,
not by me. My device just has to able to support the specified maximum
range: 105 dB nHL, which corresponds to something on the order of 140
dB RMS SPL, depending on frequency and toneburst shape.

Currently they are doing the same thing with big wall-powered devices,
I'm merely implementing the same functionality (with the same
specifications) in a portable battery-powered design.


Thanks for the suggestion, I'll look into it.

greetings,
Tom

The LM4881 is IIRC a member, a member of National Semiconductor's "boomer"
family of devices. Search for datasheets in the range LM46xx to 49xx, the
range of devices is quite large.

 

[Tim Shoppa]

Tim,



I didn't ask for "more power than an LM386", I asked for lower noise.


As I clarified in my later post to Phil the high power pulses are only
for very brief periods of time.

The audio power level given to the patients is decided by the doctors,
not by me. My device just has to able to support the specified maximum
range: 105 dB nHL, which corresponds to something on the order of 140
dB RMS SPL, depending on frequency and toneburst shape.

Currently they are doing the same thing with big wall-powered devices,
I'm merely implementing the same functionality (with the same
specifications) in a portable battery-powered design.


Thanks for the suggestion, I'll look into it.

Is this a device for diagnostic or for corrective purposes?

My gut feeling is that for potentially dangerous power levels, some
sort of "sidetone" or "noise" may be desirable as a warning that the
device is on and powered up and working (I almost want to use the word
"armed").

The low-end of TDA series audio amps (e.g. TDA2002, TDA2003 etc.) might
be interesting to you too. This series is most easily found in the
replacement parts chain rather than the design parts chain.

On a very incidentally related subject, I saw a PBS show last night
that had a short segment about cochlear implants. Fascinating stuff,
but only about 10 minutes long so now I want to know more!

Tim.

 

[Phil Allison]

** Dangerous Groper Alert !!!

Cute, thanks, but doesn't quite meet the compactness & low power
requirements...

** Seems like an ** EXTRAORDINARILY ** dangerous thing for anyone to do.

One small, technical stuff up - the subject has their hearing permanently
damaged.

Might as well be firing gun shots right next to their ears !!

I am designing an application to specifications from the medical
doctors here.

** But YOU have already demonstrated YOU have NO damn idea what you are
doing.

Tell me - are any of those alleged " doctors " related to Joseph Mengele
by any chance ??

Please don't jump to conclusions about my criminal
intentions are stupidity without knowing anything about my application.

** The OBLIGATION is on * YOU * to inform us about your so called
"application".

It would be *criminal* for anyone reading your post to attempt to emulate
what you describe and are asking us about.

You completely forget this is OPEN PUBLIC FORUM - plus, all the posts
are archived by Google and others for decades.

This is ABSOLUTELY NOT the place to discuss dangerous experiments on
humans.


I absolutely stand by my earlier comments and the heading.
------------------------------------------------------------------

Someone FAR FAR more technically competent and wise than *YOU* needs to be
given the task.

The audio driving circuits to those earpieces MUST have safety interlocks
desigjed in and 100% fool proof automatic trips if input power levels
EVER exceed what is known to cause hearing damage .




........ Phil

 

[Phil Allison]

** Dangerous Groper Alert !

I didn't ask for "more power than an LM386", I asked for lower noise.


As I clarified in my later post to Phil the high power pulses are only
for very brief periods of time.

The audio power level given to the patients is decided by the doctors,
not by me. My device just has to able to support the specified maximum
range: 105 dB nHL, which corresponds to something on the order of 140
dB RMS SPL, depending on frequency and toneburst shape.

** Seems like an ** EXTRAORDINARILY ** dangerous thing for anyone to do.

One small, technical stuff up - the subject has their hearing permanently
damaged.

Might as well be firing gun shots right next to their ears !!

I am designing an application to specifications from the medical
doctors here.

** But YOU have already demonstrated YOU have NO damn idea what you are
doing.

Tell me - are any of those alleged " doctors " related to Joseph Mengele
by any chance ??

Please don't jump to conclusions about my criminal
intentions are stupidity without knowing anything about my application.

** The OBLIGATION is on * YOU * to inform us about your so called
"application".

It would be *criminal* for anyone reading your post to attempt to emulate
what you describe and are asking us about.

You completely forget this is OPEN PUBLIC FORUM - plus, all the posts
are archived by Google and others for decades.

This is ABSOLUTELY NOT the place to discuss dangerous experiments on
humans.


I absolutely stand by my earlier comments and the heading.
------------------------------------------------------------------


Someone FAR FAR more technically competent and wise than *YOU* needs to be
given the task.

The audio driving circuits to those earpieces MUST have safety interlocks
desigjed in and 100% fool proof automatic trips if input power levels
EVER exceed what is known to cause hearing damage .



........ Phil

 

[Jim Thompson]

It's Tinnitus - a common side effect of hearing loss (or depression).
http://www.ata.org/about_tinnitus/professional/treatment.html

Tinnitus can come from drug side effects. It's thought that mine is a
result of continual aspirin therapy for arthritis. But many other
regular-use drug therapies have been implicated as well.

It can also come from too much exposure to leftist weenies ;-)

...Jim Thompson

 

[Joel Kolstad]

The audio driving circuits to those earpieces MUST have safety interlocks
desigjed in and 100% fool proof automatic trips if input power levels
EVER exceed what is known to cause hearing damage .

I'm willing to bet you that many current commercial offerings don't have the
level of interlocks you suggest, given that determining "power levels...
known to cause hearing damage" is a complex function of wave shape,
duration, the listener, etc.

Not that I know, but I bet you don't either.

Of course, some amount of interlocking should exist. It's interesting to
contemplate whether a microcontroller-based device with a DAC is more or
less likely to fail than an older design with, e.g., gated oscillator
outputs.

Always mount a scratch monkey? ...The OP would surely benefit from reading
about Theracs if he hasn't already.

 

[Homer J Simpson]

In that case lemme propose a 2 x EL34 tube amp.

At least quads of KT66s.