searching better alternative for LM386

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.

"Tim Shoppa"

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

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

Goes with the territory - IME.

....... Phil

On a sunny day (Fri, 19 Jan 2007 00:46:30 +1100) it happened "Phil Allison" wrote in :

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

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

Jan,

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

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.

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.

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

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

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

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.

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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

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

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

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

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

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

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.

At least quads of KT66s.

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

................and also lunatic fringe right wing extremists!

Nah! - you mean those transmitter tubes (TT something or other) with 2 prongs on top and run off several kV HT.

Yup. See the interlock system on the cargo doors of Boeing 747s. Cost 11 lives in one incident alone. Good luck getting a better system on a piece of electronics.

"Joel Kolstad"

Be criminally reckless not to have it.

....... Phil

(snip)

This need for a very high sound pressure level, combined with a very quiet noise level between pulses implies a need for an inherently low noise amplifier, and the LM386 just isn't going to do that. What sound pressure level do you require for the quiet times between pulses? You may have to switch the power off to the amplifier to get 120+ db (1 million to 1) ratio between the level of the pulses and the silence between them.

Thanks Phil, this was exactly the kind of feedback I was hoping for! :-)

This one: