For audophiles

[Jan Panteltje]

Needed a bit stable headphone amp for my Sennheiser HD201.
Lots of long audio cables from various sources with varying impedances around in the house..

OK, maybe LM380 (yes old days) or LM386, make a peeseebee, potmeter, connectors, housing
$+$+$+$ plus local shipment > 5 Euro (> 5 USD)...

mm ebay?
Sure!
https://www.ebay.com/itm/293190924115
9 $ and free shipping, cannot buy the parts for that (only 1 LM3.. in junkbox).

So it arrived, I build it (values are marked on peeseebee), and it works, even on 9 V!

But all the time I was wondering about the schematic:
http://panteltje.com/pub/chinese_headphone_amp_schematic_IXIMG_0191.JPG
mm an opamp output connected to a + input????

Looked up the chip datasheet, sure enough + and - input reversed in the schematic!

http://panteltje.com/pub/chinese_headphone_amplifier_build_IMG_0193.JPG

So audio-philes, there you are

Had not build a kit in many years, this was fun.

 

[bitrex]

On 10/20/19 4:52 PM, bitrex wrote:

On 10/20/19 2:28 PM, Jan Panteltje wrote:
Needed a bit stable headphone amp for my Sennheiser HD201.
Lots of long audio cables from various sources with varying impedances
around in the house..

OK, maybe LM380 (yes old days) or LM386, make a peeseebee, potmeter,
connectors, housing
$+$+$+$ plus local shipment > 5 Euro (> 5 USD)...

mm ebay?
Sure!
  https://www.ebay.com/itm/293190924115
   9 $ and free shipping, cannot buy the parts for that (only 1 LM3..
in junkbox).

So it arrived, I build it (values are marked on peeseebee), and it
works, even on 9 V!

But all the time I was wondering about the schematic:
  http://panteltje.com/pub/chinese_headphone_amp_schematic_IXIMG_0191.JPG
   mm an opamp output connected to a + input????

Looked up the chip datasheet, sure enough + and - input reversed in
the schematic!

yup

  http://panteltje.com/pub/chinese_headphone_amplifier_build_IMG_0193.JPG

So audio-philes, there you are

Had not build a kit in many years, this was fun.


Some 1-2.2k resistors pulled down from the op amp outputs to -Vcc would
keep the 5532s in class A longer at low volumes.

though say 32 ohm headphones seems like a kinda brutal load even for 2
in parallel. I think their max continual AC is like 10mA? and it's
asymmetrical

A "real audiophile" would use LM1368s or suchlike serious overkill

Sorry I mean LT1368

 

[bitrex]

On 10/20/19 2:28 PM, Jan Panteltje wrote:

Needed a bit stable headphone amp for my Sennheiser HD201.
Lots of long audio cables from various sources with varying impedances around in the house..

OK, maybe LM380 (yes old days) or LM386, make a peeseebee, potmeter, connectors, housing
$+$+$+$ plus local shipment > 5 Euro (> 5 USD)...

mm ebay?
Sure!
https://www.ebay.com/itm/293190924115
9 $ and free shipping, cannot buy the parts for that (only 1 LM3.. in junkbox).

So it arrived, I build it (values are marked on peeseebee), and it works, even on 9 V!

But all the time I was wondering about the schematic:
http://panteltje.com/pub/chinese_headphone_amp_schematic_IXIMG_0191.JPG
mm an opamp output connected to a + input????

Looked up the chip datasheet, sure enough + and - input reversed in the schematic!

yup

http://panteltje.com/pub/chinese_headphone_amplifier_build_IMG_0193.JPG

So audio-philes, there you are

Had not build a kit in many years, this was fun.

Some 1-2.2k resistors pulled down from the op amp outputs to -Vcc would
keep the 5532s in class A longer at low volumes.

though say 32 ohm headphones seems like a kinda brutal load even for 2
in parallel. I think their max continual AC is like 10mA? and it's
asymmetrical

A "real audiophile" would use LM1368s or suchlike serious overkill

 

[Cursitor Doom]

On Sun, 20 Oct 2019 18:28:34 +0000, Jan Panteltje wrote:

So audio-philes, there you are

Had not build a kit in many years, this was fun.

Great, all you need now is a pair of 47 Amp headphones to go with it! :-D

Seriously, though - a board from China with its own enclosure! They are
really come on these days. ;-)



--
This message may be freely reproduced without limit or charge only via
the Usenet protocol. Reproduction in whole or part through other
protocols, whether for profit or not, is conditional upon a charge of
GBP10.00 per reproduction. Publication in this manner via non-Usenet
protocols constitutes acceptance of this condition.

 

[Robert Baer]

bitrex wrote:

On 10/20/19 2:28 PM, Jan Panteltje wrote:
Needed a bit stable headphone amp for my Sennheiser HD201.
Lots of long audio cables from various sources with varying impedances
around in the house..

OK, maybe LM380 (yes old days) or LM386, make a peeseebee, potmeter,
connectors, housing
$+$+$+$ plus local shipment > 5 Euro (> 5 USD)...

mm ebay?
Sure!
  https://www.ebay.com/itm/293190924115
   9 $ and free shipping, cannot buy the parts for that (only 1 LM3..
in junkbox).

So it arrived, I build it (values are marked on peeseebee), and it
works, even on 9 V!

But all the time I was wondering about the schematic:
  http://panteltje.com/pub/chinese_headphone_amp_schematic_IXIMG_0191.JPG
   mm an opamp output connected to a + input????

Looked up the chip datasheet, sure enough + and - input reversed in
the schematic!

yup

  http://panteltje.com/pub/chinese_headphone_amplifier_build_IMG_0193.JPG

So audio-philes, there you are

Had not build a kit in many years, this was fun.


Some 1-2.2k resistors pulled down from the op amp outputs to -Vcc would
keep the 5532s in class A longer at low volumes.

though say 32 ohm headphones seems like a kinda brutal load even for 2
in parallel. I think their max continual AC is like 10mA? and it's
asymmetrical

A "real audiophile" would use LM1368s or suchlike serious overkill





Audiophools pay big bux for overkill..

 

[Phil Allison]

Jan Panteltje is Nuts wrote:

------------------------------

Needed a bit stable headphone amp for my Sennheiser HD201.

** "bit stable" = wot ?

https://www.ebay.com/itm/293190924115

So it arrived, I build it (values are marked on peeseebee),
and it works, even on 9 V!

** But very badly.

But all the time I was wondering about the schematic:
http://panteltje.com/pub/chinese_headphone_amp_schematic_IXIMG_0191.JPG

** Not Found Error

That design is very poor - even with +/-15Vsupplies an NE5532 is not up to the task.


...... Phil

 

[Jan Panteltje]

On a sunny day (Sun, 20 Oct 2019 16:54:34 -0400) it happened bitrex
<user@example.net> wrote in <fQ3rF.297896$LC2.295315@fx45.iad>:

>Sorry I mean LT1368

Interesting chip.

Yes, for my ears I do not drive the Chinese thing at full volume,
so 47 Ohm is OK, the feedback will give a flat range.

Did not hear any distortion, it is less than my piezo tweeters in the high ;-)

I did put a piece of yellow heatshrink over the blue LED..

 

[Jan Panteltje]

On a sunny day (Sun, 20 Oct 2019 17:48:33 -0700 (PDT)) it happened Kill
Allison <pallison49@gmail.com> wrote in
<7ef88a67-ee5e-41f2-b253-781109de9f07@googlegroups.com>:

Jan Panteltje the true audiophile

------------------------------

Needed a bit stable headphone amp for my Sennheiser HD201.


** "bit stable" = wot ?


https://www.ebay.com/itm/293190924115

So it arrived, I build it (values are marked on peeseebee),
and it works, even on 9 V!


** But very badly.


But all the time I was wondering about the schematic:
http://panteltje.com/pub/chinese_headphone_amp_schematic_IXIMG_0191.JPG

** Not Found Error

You need a computah for that.

That design is very poor - even with +/-15Vsupplies an NE5532 is not up to the task.

I guess it all depends on your volume and hearing.
I played some music via it for test and it was good enough for me.
Even could hear test tones much higher than I thought I could
was even looking at weatherfax pictures...
The subtle trebble and deep basses in a transparent 4D acoustic picture
make for an immersing deep connected warm sound experience,
;-)

 

[Phil Allison]

Jan Panteltje Raving Wog Nutbag wrote:

-------------------------------------

Needed a bit stable headphone amp for my Sennheiser HD201.


** "bit stable" = wot ?

** How mysterious ...

https://www.ebay.com/itm/293190924115

So it arrived, I build it (values are marked on peeseebee),
and it works, even on 9 V!


** But very badly.

** Stunned silence ....

But all the time I was wondering about the schematic:
http://panteltje.com/pub/chinese_headphone_amp_schematic_IXIMG_0191.JPG

** Not Found Error

You need a computah for that.

** You need a brain that ain't so faulty.

That design is very poor - even with +/-15Vsupplies an NE5532 is not up to the task.


I guess it all depends on your volume and hearing.

** You guess everything.

Then you post BULLSHIT !!



...... Phil

 

On Sunday, 20 October 2019 19:28:54 UTC+1, Jan Panteltje wrote:

Needed a bit stable headphone amp for my Sennheiser HD201.
Lots of long audio cables from various sources with varying impedances around in the house..

OK, maybe LM380 (yes old days) or LM386, make a peeseebee, potmeter, connectors, housing
$+$+$+$ plus local shipment > 5 Euro (> 5 USD)...

mm ebay?
Sure!
https://www.ebay.com/itm/293190924115
9 $ and free shipping, cannot buy the parts for that (only 1 LM3.. in junkbox).

lucky you avoided the LM386. Sound of those not good.


NT

 

[bitrex]

On 10/21/19 3:12 AM, Jan Panteltje wrote:

On a sunny day (Sun, 20 Oct 2019 16:54:34 -0400) it happened bitrex
user@example.net> wrote in <fQ3rF.297896$LC2.295315@fx45.iad>:

Sorry I mean LT1368

Interesting chip.

It is but I got the number wrong again! I meant LT1364. That's more like
it with respect to "audiophile" heh heh

Yes, for my ears I do not drive the Chinese thing at full volume,
so 47 Ohm is OK, the feedback will give a flat range.

Did not hear any distortion, it is less than my piezo tweeters in the high ;-)

I did put a piece of yellow heatshrink over the blue LED..

 

[Jan Panteltje]

On a sunny day (Mon, 21 Oct 2019 01:22:08 -0700 (PDT)) it happened Kill
Allison <pallison49@gmail.com> wrote in
<7b9108f7-5a0e-43ee-a99d-d69f418aa0b1@googlegroups.com>:

But all the time I was wondering about the schematic:
http://panteltje.com/pub/chinese_headphone_amp_schematic_IXIMG_0191.JPG

** Not Found Error

You need a computah for that.

Later ...
I remembered I had an downed under I{ that could not access my servers at that time those ran at home
As sysadm I contacted them on behalf of their customer (who complained to me)
and had them check their routing

But as you are such a genius you could do the following in a real Linux computer:

Type
host panteltje.com
that should show:
panteltje.com has address 37.148.205.129

Then type
traceroute 37.148.205.129
see where it gets stuck

Then look up the IP where it gets stuck.
(ip_to_country)
Very likely down under, problem you get when everything is upside down and water flows all over y'r hat.


Then contact your ISP's sys administrator, complain, show them the log you just made
and hope they know enough to fix it.

Bit isolated down there I guess without access to EU internet

If you were a bit polite I would do it 4 you, but I leave the chance to you to actually learn something more
than insulting.

killfile

 

[Jan Panteltje]

On a sunny day (Mon, 21 Oct 2019 05:14:56 -0400) it happened bitrex
<user@example.net> wrote in <kGerF.303980$LC2.243916@fx45.iad>:

On 10/21/19 3:12 AM, Jan Panteltje wrote:
On a sunny day (Sun, 20 Oct 2019 16:54:34 -0400) it happened bitrex
user@example.net> wrote in <fQ3rF.297896$LC2.295315@fx45.iad>:

Sorry I mean LT1368

Interesting chip.

It is but I got the number wrong again! I meant LT1364. That's more like
it with respect to "audiophile" heh heh

Yes, for my ears I do not drive the Chinese thing at full volume,
so 47 Ohm is OK, the feedback will give a flat range.

Did not hear any distortion, it is less than my piezo tweeters in the high ;-)

I did put a piece of yellow heatshrink over the blue LED..

So harmonic distortion <= 0.02 % at 20 kHz..

I think there are many chips that qualify to drive a few Ohms headphone.
I measure about 26 Ohm at DC for my Sennheiser....

The OLD LM380 was OK for monitoring, high-fi I am not so sure,
depends on where you extraterrestrial perception is.

Much of that audio is in the imagination.

I remember going with an audio line amplifier to the test lab,
designed it together with my boss, and it got accepted.. for TV broadcast that is.
I was really surprised, expected a big fight, cannot remember what crannies were in it,
And an amplifier for optical cell in a 35 mm projector, that sort optical track audio was not what you
today would call HiFi.

So, I can still hear 10 kHz, not bad at my age ..
2345 audio / music tracks on this laptop..

Yesterday I burned DVD number 999.
Big light proof alu box is now full.
Added an other 3 TB drive in PC number 2.
rarely have time to listen to music these days,
just got a new Raspberry Pi4 and am rewriting the code...


bbzz that new Pi4 does not even play HEVC video, bummer,
my Chinese 30 $ DVB-T2 box with build in power supply does.
Raspberry.org is moving in the wrong direction I think.
Much stuff does not even install on 'buster'

Video
ID : 7031 (0x1B77)
Menu ID : 730 (0x2DA)
Format : HEVC
Format/Info : High Efficiency Video Coding
Format profile : Main@L4.1@Main
Codec ID : 36
Duration : 1 h 45 min
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate : 50.000 FPS
Color space : YUV
Chroma subsampling : 4:2:0 (Type 0)
no go.

The stones in where was it .. Cuba, interviews South America..

Recoding with ffmpeg to H264 runs at 6.5 frames per second, took all night...
Those guys just keep going.

OK, back on topic :=)

 

[Don Kuenz]

typo corrected below

Jan Panteltje <pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Mon, 21 Oct 2019 01:22:08 -0700 (PDT)) it happened Kill
Allison <pallison49@gmail.com> wrote in
7b9108f7-5a0e-43ee-a99d-d69f418aa0b1@googlegroups.com>:




But all the time I was wondering about the schematic:
http://panteltje.com/pub/chinese_headphone_amp_schematic_IXIMG_0191.JPG

** Not Found Error

You need a computah for that.


Later ...
I remembered I had an downed under I{ that could not access my servers
at that time those ran at home
As sysadm I contacted them on behalf of their customer (who complained to me)
and had them check their routing

But as you are such a genius you could do the following in a real Linux computer:

Type
host panteltje.com
that should show:
panteltje.com has address 37.148.205.129

Then type
traceroute 37.148.205.129
see where it gets stuck

Then look up the IP where it gets stuck.
(ip_to_country)
Very likely down under, problem you get when everything is upside down and wat
er flows all over y'r hat.


Then contact your ISP's sys administrator, complain, show them the log
you just made
and hope they know enough to fix it.

Bit isolated down there I guess without access to EU internet

If you were a bit polite I would do it 4 you, but I leave the chance to
you to actually learn something more than insulting.

killfile

That's the best place to kennel Cretin the insult dog. Him and his
little buddy further up keep insisting that my own mixer amp
http://michael2.home.crcomp.net/electronic/mixeramp/index.php suffers
from distortion. They apparently use their ESP to diagnose it.
Anyhow, your jpg shows up just fine for me. My own circuit uses a
TEA2025B. It delivers a full bodied exquisite sound even when the
volume's turned up to enable me to hear it in the next room.

Thank you, 73,

--
Don Kuenz KB7RPU
There was a young lady named Bright Whose speed was far faster than light;
She set out one day In a relative way And returned on the previous night.

 

[Don Kuenz]

Jan Panteltje <pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Mon, 21 Oct 2019 01:22:08 -0700 (PDT)) it happened Kill
Allison <pallison49@gmail.com> wrote in
7b9108f7-5a0e-43ee-a99d-d69f418aa0b1@googlegroups.com>:




But all the time I was wondering about the schematic:
http://panteltje.com/pub/chinese_headphone_amp_schematic_IXIMG_0191.JPG

** Not Found Error

You need a computah for that.


Later ...
I remembered I had an downed under I{ that could not access my servers
at that time those ran at home
As sysadm I contacted them on behalf of their customer (who complained to me)
and had them check their routing

But as you are such a genius you could do the following in a real Linux computer:

Type
host panteltje.com
that should show:
panteltje.com has address 37.148.205.129

Then type
traceroute 37.148.205.129
see where it gets stuck

Then look up the IP where it gets stuck.
(ip_to_country)
Very likely down under, problem you get when everything is upside down and wat
er flows all over y'r hat.


Then contact your ISP's sys administrator, complain, show them the log
you just made
and hope they know enough to fix it.

Bit isolated down there I guess without access to EU internet

If you were a bit polite I would do it 4 you, but I leave the chance to
you to actually learn something more than insulting.

killfile

That's the best place to kennel Cretin the insult dog. Him and his
little buddy further up keep insisting that my own mixer amp
http://michael2.home.crcomp.net/electronic/mixeramp/index.php suffers
from distortion. They apparently use their ESP to diagnosis it.
Anyhow, your jpg shows up just fine for me. My own circuit uses a
TEA2025B. It delivers a full bodied exquisite sound even when the
volume's turned up to enable me to hear it in the next room.

Thank you, 73,

--
Don Kuenz KB7RPU
There was a young lady named Bright Whose speed was far faster than light;
She set out one day In a relative way And returned on the previous night.

 

[bitrex]

On 10/21/19 5:17 AM, tabbypurr@gmail.com wrote:

On Sunday, 20 October 2019 19:28:54 UTC+1, Jan Panteltje wrote:
Needed a bit stable headphone amp for my Sennheiser HD201.
Lots of long audio cables from various sources with varying impedances around in the house..

OK, maybe LM380 (yes old days) or LM386, make a peeseebee, potmeter, connectors, housing
$+$+$+$ plus local shipment > 5 Euro (> 5 USD)...

mm ebay?
Sure!
https://www.ebay.com/itm/293190924115
9 $ and free shipping, cannot buy the parts for that (only 1 LM3.. in junkbox).

lucky you avoided the LM386. Sound of those not good.


NT

They're nice for a lot of tasks like solenoid and servos, driving small
brushed DC motors and other applications other than audio. The DIP-8
version LM386N is very rugged and can dissipate a fair amount of power
(a small copper heat sink thermal epoxied to the top helps.) It can
drive a 30mm brushed DC motor like in an RC car.

 

[Don Kuenz]

typo corrected below and now link below fixed

Jan Panteltje <pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Mon, 21 Oct 2019 01:22:08 -0700 (PDT)) it happened Kill
Allison <pallison49@gmail.com> wrote in
7b9108f7-5a0e-43ee-a99d-d69f418aa0b1@googlegroups.com>:




But all the time I was wondering about the schematic:
http://panteltje.com/pub/chinese_headphone_amp_schematic_IXIMG_0191.JPG

** Not Found Error

You need a computah for that.


Later ...
I remembered I had an downed under I{ that could not access my servers
at that time those ran at home
As sysadm I contacted them on behalf of their customer (who complained to me)
and had them check their routing

But as you are such a genius you could do the following in a real Linux computer:

Type
host panteltje.com
that should show:
panteltje.com has address 37.148.205.129

Then type
traceroute 37.148.205.129
see where it gets stuck

Then look up the IP where it gets stuck.
(ip_to_country)
Very likely down under, problem you get when everything is upside down and wat
er flows all over y'r hat.


Then contact your ISP's sys administrator, complain, show them the log
you just made
and hope they know enough to fix it.

Bit isolated down there I guess without access to EU internet

If you were a bit polite I would do it 4 you, but I leave the chance to
you to actually learn something more than insulting.

killfile

That's the best place to kennel Cretin the insult dog. Him and his
little buddy further up keep insisting that my own mixer amp
http://crcomp.net/electronic/mixeramp/index.php suffers from distortion.
They apparently use their ESP to diagnose it.
Anyhow, your jpg shows up just fine for me. My own circuit uses a
TEA2025B. It delivers a full bodied exquisite sound even when the
volume's turned up to enable me to hear it in the next room.

Thank you, 73,

--
Don Kuenz KB7RPU
There was a young lady named Bright Whose speed was far faster than light;
She set out one day In a relative way And returned on the previous night.

 

On Monday, 21 October 2019 16:43:16 UTC+1, bitrex wrote:

On 10/21/19 5:17 AM, tabbypurr wrote:
On Sunday, 20 October 2019 19:28:54 UTC+1, Jan Panteltje wrote:

Needed a bit stable headphone amp for my Sennheiser HD201.
Lots of long audio cables from various sources with varying impedances around in the house..

OK, maybe LM380 (yes old days) or LM386, make a peeseebee, potmeter, connectors, housing
$+$+$+$ plus local shipment > 5 Euro (> 5 USD)...

mm ebay?
Sure!
https://www.ebay.com/itm/293190924115
9 $ and free shipping, cannot buy the parts for that (only 1 LM3.. in junkbox).

lucky you avoided the LM386. Sound of those not good.


NT


They're nice for a lot of tasks like solenoid and servos, driving small
brushed DC motors and other applications other than audio. The DIP-8
version LM386N is very rugged and can dissipate a fair amount of power
(a small copper heat sink thermal epoxied to the top helps.) It can
drive a 30mm brushed DC motor like in an RC car.

I think it's the world's most popular audio power amp IC. (Maybe the one with the most distortion too.)


NT

 

[Jan Panteltje]

On a sunny day (Mon, 21 Oct 2019 21:42:44 -0700 (PDT)) it happened
tabbypurr@gmail.com wrote in
<2147376f-2e89-441c-b6a4-143353e7ae67@googlegroups.com>:

On Monday, 21 October 2019 16:43:16 UTC+1, bitrex wrote:
On 10/21/19 5:17 AM, tabbypurr wrote:
On Sunday, 20 October 2019 19:28:54 UTC+1, Jan Panteltje wrote:

Needed a bit stable headphone amp for my Sennheiser HD201.
Lots of long audio cables from various sources with varying impedances around in the house..

OK, maybe LM380 (yes old days) or LM386, make a peeseebee, potmeter, connectors, housing
$+$+$+$ plus local shipment > 5 Euro (> 5 USD)...

mm ebay?
Sure!
https://www.ebay.com/itm/293190924115
9 $ and free shipping, cannot buy the parts for that (only 1 LM3.. in junkbox).

lucky you avoided the LM386. Sound of those not good.


NT


They're nice for a lot of tasks like solenoid and servos, driving small
brushed DC motors and other applications other than audio. The DIP-8
version LM386N is very rugged and can dissipate a fair amount of power
(a small copper heat sink thermal epoxied to the top helps.) It can
drive a 30mm brushed DC motor like in an RC car.

I think it's the world's most popular audio power amp IC. (Maybe the one with the most distortion too.)


NT

Did some more tests with the Chinese thing last night.
I think the damping on my headphones is not so good, that results in some
suspicious 's' sounds in some speech.
It is a large headphone that behaves a lot like a dynamic speaker...

So, maybe I will add a LM380 or LM386 to compare,
and see if I can get any of the chips bitrex mentioned.
Space enough in that plastic housing.
I have to keep resisting buying a couple of Quad electrostats on ebay for a thousand or so..
I really like those speakers (were also used as monitor in the studio sound control room),

They had, in their amps an interesting feed forward (IIRC) distortion compensation.
Build a circuit like that once for about 100 kHz for an inductive loop system.

 

On Tuesday, 22 October 2019 07:32:25 UTC+1, Jan Panteltje wrote:

21 Oct 2019 tabbypurr wrote in
2147376f-2e89-441c-b6a4-143353e7ae67@googlegroups.com>:
On Monday, 21 October 2019 16:43:16 UTC+1, bitrex wrote:
On 10/21/19 5:17 AM, tabbypurr wrote:

lucky you avoided the LM386. Sound of those not good.

They're nice for a lot of tasks like solenoid and servos, driving small
brushed DC motors and other applications other than audio. The DIP-8
version LM386N is very rugged and can dissipate a fair amount of power
(a small copper heat sink thermal epoxied to the top helps.) It can
drive a 30mm brushed DC motor like in an RC car.

I think it's the world's most popular audio power amp IC. (Maybe the one with the most distortion too.)

Did some more tests with the Chinese thing last night.
I think the damping on my headphones is not so good, that results in some
suspicious 's' sounds in some speech.
It is a large headphone that behaves a lot like a dynamic speaker...

So, maybe I will add a LM380 or LM386 to compare,
and see if I can get any of the chips bitrex mentioned.
Space enough in that plastic housing.

The 386 has a very characteristic sound. I don't know what type of distortion causes it - I wonder if it might be slew rate limitation, but don't know.

I have to keep resisting buying a couple of Quad electrostats on ebay for a thousand or so..
I really like those speakers (were also used as monitor in the studio sound control room),

exceptionally nice speakers.


NT

They had, in their amps an interesting feed forward (IIRC) distortion compensation.
Build a circuit like that once for about 100 kHz for an inductive loop system.