LM1877N IC for headphone amp?

[Rich Wilner]

hey all
I recently got 4 of these from a friend who was going to use them but
didn't, and I would like to build myself a little headphone amp so I
can take my sennheisers with me on the road and use my portable mp3
player (headphone amp in mp3 player = garbage).
anyone have any experience with these ICs, or have any schematics for
this specific app? Just wondering before I start breadboarding.
a link to the info:
http://www.national.com/pf/LM/LM1877.html
thanks
Rich

[Stephen Sank]

That series of antique NatSemi amp chips is quite prone to oscillation. I
think you'd find it far easier in the long run, and better sounding, to
stick a pair of small output transistors on the output of a each channel of
a 4558 variety opamp(e.g., M5218, uPC4570, OP275, OPA2134, etc.).

--
Stephen Sank, Owner & Ribbon Mic Restorer
Talking Dog Transducer Company
http://stephensank.com
5517 Carmelita Drive N.E.
Albuquerque, New Mexico [87111]
505-332-0336
Auth. Nakamichi & McIntosh servicer
Payments preferred through Paypal.com
"Rich Wilner" > wrote in message
om...
> hey all
> I recently got 4 of these from a friend who was going to use them but
> didn't, and I would like to build myself a little headphone amp so I
> can take my sennheisers with me on the road and use my portable mp3
> player (headphone amp in mp3 player = garbage).
> anyone have any experience with these ICs, or have any schematics for
> this specific app? Just wondering before I start breadboarding.
> a link to the info:
> http://www.national.com/pf/LM/LM1877.html
> thanks
> Rich

[Stephen Sank]

That series of antique NatSemi amp chips is quite prone to oscillation. I
think you'd find it far easier in the long run, and better sounding, to
stick a pair of small output transistors on the output of a each channel of
a 4558 variety opamp(e.g., M5218, uPC4570, OP275, OPA2134, etc.).

--
Stephen Sank, Owner & Ribbon Mic Restorer
Talking Dog Transducer Company
http://stephensank.com
5517 Carmelita Drive N.E.
Albuquerque, New Mexico [87111]
505-332-0336
Auth. Nakamichi & McIntosh servicer
Payments preferred through Paypal.com
"Rich Wilner" > wrote in message
om...
> hey all
> I recently got 4 of these from a friend who was going to use them but
> didn't, and I would like to build myself a little headphone amp so I
> can take my sennheisers with me on the road and use my portable mp3
> player (headphone amp in mp3 player = garbage).
> anyone have any experience with these ICs, or have any schematics for
> this specific app? Just wondering before I start breadboarding.
> a link to the info:
> http://www.national.com/pf/LM/LM1877.html
> thanks
> Rich

[Frank Vuotto]

A transformer isn't really needed. The Mackie HP amps sound decent and
they use "stacked" opamps, (I usually use 5532's). There's a schematic
at the link below >Taos Amp >Floobydust.

Frank /~ http://newmex.com/f10
@/ 36°x105°



On Fri, 3 Oct 2003 06:07:42 -0600, "Stephen Sank" >
wrote:

>That series of antique NatSemi amp chips is quite prone to oscillation. I
>think you'd find it far easier in the long run, and better sounding, to
>stick a pair of small output transistors on the output of a each channel of
>a 4558 variety opamp(e.g., M5218, uPC4570, OP275, OPA2134, etc.).

[Frank Vuotto]

A transformer isn't really needed. The Mackie HP amps sound decent and
they use "stacked" opamps, (I usually use 5532's). There's a schematic
at the link below >Taos Amp >Floobydust.

Frank /~ http://newmex.com/f10
@/ 36°x105°



On Fri, 3 Oct 2003 06:07:42 -0600, "Stephen Sank" >
wrote:

>That series of antique NatSemi amp chips is quite prone to oscillation. I
>think you'd find it far easier in the long run, and better sounding, to
>stick a pair of small output transistors on the output of a each channel of
>a 4558 variety opamp(e.g., M5218, uPC4570, OP275, OPA2134, etc.).

[Rich Wilner]

Frank Vuotto > wrote in message >...
> A transformer isn't really needed. The Mackie HP amps sound decent and
> they use "stacked" opamps, (I usually use 5532's). There's a schematic
> at the link below >Taos Amp >Floobydust.
>

yeah, i built these before and wasn't satisfied with the fidelity, a
bit harsh sounding over long periods.
anyone have experience with/schematics for the LM4881 "boomer" IC?

[Rich Wilner]

Frank Vuotto > wrote in message >...
> A transformer isn't really needed. The Mackie HP amps sound decent and
> they use "stacked" opamps, (I usually use 5532's). There's a schematic
> at the link below >Taos Amp >Floobydust.
>

yeah, i built these before and wasn't satisfied with the fidelity, a
bit harsh sounding over long periods.
anyone have experience with/schematics for the LM4881 "boomer" IC?

[Gene Pool]

Check out the schematic paia has on their site for the 5532 headphone
amp:

http://paia.com/hdasch.gif



On 2 Oct 2003 18:59:56 -0700, (Rich Wilner)
wrote:

>hey all
>I recently got 4 of these from a friend who was going to use them but
>didn't, and I would like to build myself a little headphone amp so I
>can take my sennheisers with me on the road and use my portable mp3
>player (headphone amp in mp3 player = garbage).
>anyone have any experience with these ICs, or have any schematics for
>this specific app? Just wondering before I start breadboarding.
>a link to the info:
>http://www.national.com/pf/LM/LM1877.html
>thanks
>Rich

[Gene Pool]

Check out the schematic paia has on their site for the 5532 headphone
amp:

http://paia.com/hdasch.gif



On 2 Oct 2003 18:59:56 -0700, (Rich Wilner)
wrote:

>hey all
>I recently got 4 of these from a friend who was going to use them but
>didn't, and I would like to build myself a little headphone amp so I
>can take my sennheisers with me on the road and use my portable mp3
>player (headphone amp in mp3 player = garbage).
>anyone have any experience with these ICs, or have any schematics for
>this specific app? Just wondering before I start breadboarding.
>a link to the info:
>http://www.national.com/pf/LM/LM1877.html
>thanks
>Rich

[Pooh Bear]

Rich Wilner wrote:

> hey all
> I recently got 4 of these from a friend who was going to use them but
> didn't, and I would like to build myself a little headphone amp so I
> can take my sennheisers with me on the road and use my portable mp3
> player (headphone amp in mp3 player = garbage).
> anyone have any experience with these ICs, or have any schematics for
> this specific app? Just wondering before I start breadboarding.

All the 'dedicated headphone ICs' tend to be targeted at consumer
applications e.g single supply rail - indifferent performance.

The best op-amp I have found for the job is New Japan Radio's NJM4556 -
at least I think that's the one - lol. It has a an output current of 70mA
( can drive 200 ohms directly ) which is typically twice that of most
other pro-audio op-amps and good characteristics all round. Connect the
outputs of two in parallel via current sharing resistors of say 10 ohms
and get +/- 140mA pk.


Graham

[Pooh Bear]

Rich Wilner wrote:

> hey all
> I recently got 4 of these from a friend who was going to use them but
> didn't, and I would like to build myself a little headphone amp so I
> can take my sennheisers with me on the road and use my portable mp3
> player (headphone amp in mp3 player = garbage).
> anyone have any experience with these ICs, or have any schematics for
> this specific app? Just wondering before I start breadboarding.

All the 'dedicated headphone ICs' tend to be targeted at consumer
applications e.g single supply rail - indifferent performance.

The best op-amp I have found for the job is New Japan Radio's NJM4556 -
at least I think that's the one - lol. It has a an output current of 70mA
( can drive 200 ohms directly ) which is typically twice that of most
other pro-audio op-amps and good characteristics all round. Connect the
outputs of two in parallel via current sharing resistors of say 10 ohms
and get +/- 140mA pk.


Graham