Audio Amp Crossover Distortion?

B

Bill Bowden

Guest
I see excessive crossover distortion with this audio amp not shown
with LTspice. It simulates ok, but the wired circuit produces about a
50uS dead time step as the signal crosses the mid point. I tried
increasing the bias with no help. Both inputs to the op-amp look good
with no distortion. Any idea what is going on?

Version 4
SHEET 1 880 1108
WIRE -128 80 -128 48
WIRE -128 80 -352 80
WIRE 80 80 -128 80
WIRE 208 80 80 80
WIRE -352 96 -352 80
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WIRE 208 176 208 160
WIRE -416 208 -432 208
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WIRE 432 320 400 320
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WIRE 80 544 80 512
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WIRE 16 608 16 448
WIRE 320 608 320 320
WIRE 320 608 16 608
FLAG -80 288 +V
FLAG -480 416 +V
FLAG -480 528 0
FLAG -80 384 0
FLAG 432 400 0
FLAG -512 224 0
FLAG -352 336 0
FLAG 208 544 0
FLAG -208 336 +V
FLAG 80 544 0
FLAG -208 560 0
FLAG -128 48 +V
SYMBOL voltage -480 416 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
WINDOW 0 44 23 Left 0
WINDOW 3 51 56 Left 0
SYMATTR InstName V1
SYMATTR Value 8
SYMBOL pnp 144 272 M180
SYMATTR InstName Q1
SYMATTR Value 2N2905A
SYMBOL npn 144 368 R0
SYMATTR InstName Q2
SYMATTR Value 2N2219A
SYMBOL res 64 112 R0
SYMATTR InstName R1
SYMATTR Value 120
SYMBOL res 64 224 R0
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SYMATTR Value 560
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WINDOW 0 0 32 VBottom 0
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SYMATTR Value SINE(0 .25 1000)
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SYMATTR Value 10k
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SYMATTR Value 20k
SYMBOL cap -352 192 R90
WINDOW 0 0 32 VBottom 0
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SYMATTR InstName C4
SYMATTR Value 1ľ
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WINDOW 0 -37 42 Left 0
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SYMATTR Value 2k
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SYMATTR InstName U2
SYMBOL res 192 64 R0
SYMATTR InstName R12
SYMATTR Value .2
TEXT -504 600 Left 0 !.tran 0 100m 0 startup
 
"Bill Bowden"

I see excessive crossover distortion with this audio amp not shown
with LTspice. It simulates ok, but the wired circuit produces about a
50uS dead time step as the signal crosses the mid point. I tried
increasing the bias with no help. Both inputs to the op-amp look good
with no distortion. Any idea what is going on?


** You need to post a schematic - dickhead.

Totally SMARTARSE of you to post only a Spice list on SEB.




.... Phil
 
On 2012-01-12, Phil Allison <phil_a@tpg.com.au> wrote:
"Bill Bowden"

I see excessive crossover distortion with this audio amp not shown
with LTspice. It simulates ok, but the wired circuit produces about a
50uS dead time step as the signal crosses the mid point. I tried
increasing the bias with no help. Both inputs to the op-amp look good
with no distortion. Any idea what is going on?


** You need to post a schematic - dickhead.

Totally SMARTARSE of you to post only a Spice list on SEB.
Click to expand...
open it with ltspice and you can see the schematic

It's not just a netlist.

--
⚂⚃ 100% natural

--- Posted via news://freenews.netfront.net/ - Complaints to news@netfront.net ---
 
Phil Allison wrote:
"Bill Bowden"

I see excessive crossover distortion with this audio amp not shown
with LTspice. It simulates ok, but the wired circuit produces about a
50uS dead time step as the signal crosses the mid point. I tried
increasing the bias with no help. Both inputs to the op-amp look good
with no distortion. Any idea what is going on?

** You need to post a schematic - dickhead.

Totally SMARTARSE of you to post only a Spice list on SEB.
Click to expand...

Grow up, jackass. Download and install LTspice IV:
http://www.linear.com/designtools/software/


--
You can't have a sense of humor, if you have no sense.
 
"Jasen Betts = TROLLING PSYCHO PARROT "
** You need to post a schematic - dickhead.

Totally SMARTARSE of you to post only a Spice list on SEB.

open it with ltspice and you can see the schematic
Click to expand...

** Fuck off to hell !!!

You MORONIC pile of Kiwi sheep shagging shit.
 
"Michael A. Terrell"


** Go eat shit

- you rabid pile of ASD fucked Septic garbage.
 
"Bill Bowden = fuckwit TROLL"

I see excessive crossover distortion with this audio amp not shown
with LTspice. It simulates ok, but the wired circuit produces about a
50uS dead time step as the signal crosses the mid point. I tried
increasing the bias with no help. Both inputs to the op-amp look good
with no distortion. Any idea what is going on?


** Yeah - you fucked up as bloody usual.





.... Phil
 
On Thu, 12 Jan 2012 23:28:59 +1100 "Phil Allison" <phil_a@tpg.com.au>
wrote in Message id: <9n820mFoqfU1@mid.individual.net>:

"Jasen Betts = TROLLING PSYCHO PARROT "


** You need to post a schematic - dickhead.

Totally SMARTARSE of you to post only a Spice list on SEB.

open it with ltspice and you can see the schematic


** Fuck off to hell !!!

You MORONIC pile of Kiwi sheep shagging shit.
Click to expand...
What's the matter Phil? The ol' inner child striking out because your old
man butt fucked you as a kid?
 
On Thu, 12 Jan 2012 15:55:05 +1100, Phil Allison wrote:

** You need to post a schematic - dickhead.

Totally SMARTARSE of you to post only a Spice list on SEB.
Click to expand...
What he posted *is* a schematic.

--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
(Richard Feynman)
 
On Jan 11, 11:55 pm, "Phil Allison" <phi...@tpg.com.au> wrote:
"Bill Bowden"

I see excessive crossover distortion with this audio amp not shown
with LTspice. It simulates ok, but the wired circuit produces about a
50uS dead time step as the signal crosses the mid point. I tried
increasing the bias with no help. Both inputs to the op-amp look good
with no distortion. Any idea what is going on?

** You need to post a schematic  -  dickhead.

Totally  SMARTARSE of you to post only a Spice list on SEB.

...  Phil
Click to expand...
I was going to say it's a push-pull.... but it's flipped about.

Here's a pic
http://imageshack.us/photo/my-images/708/crossover.jpg/

Does this output have a name?

George H.
 
Phil Allison wrote:
"Michael A. Terrell"

** Go eat shit
Click to expand...

No one wants your lunch.


- you rabid pile of ASD fucked Septic garbage.
Click to expand...

You're still at the six year old level of half assed insults, I see.
You're the one with a reputation for gay sex.


--
You can't have a sense of humor, if you have no sense.
 
On Wed, 11 Jan 2012 20:14:05 -0800, Bill Bowden wrote:

I see excessive crossover distortion with this audio amp not shown with
LTspice. It simulates ok, but the wired circuit produces about a 50uS
dead time step as the signal crosses the mid point. I tried increasing
the bias with no help. Both inputs to the op-amp look good with no
distortion. Any idea what is going on?
Click to expand...
If you look at the opamp output in the simulation you'll see that it has
some near-vertical segments at crossover -- this means you're working the
amp pretty hard, and it's an opportunity for Bad Things to happen.

Make sure that the slew rate, DC gain, and gain-bandwidth product of your
"universal" op-amp matches the data sheet for what you're using. You may
want to check the real op-amp's output impedance, if it's even listed.
If not, try tossing a 600 ohm resistor in series with your op-amp's
output, see what that does.

And take a look at your real op-amp output in your real circuit; see what
it's doing.

Beyond that -- I dunno.

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com
 
"Fred Abse"
Phil Allison wrote:
** You need to post a schematic - dickhead.

Totally SMARTARSE of you to post only a Spice list on SEB.

What he posted *is* a schematic.
Click to expand...
** Fuckwit, pedantic twaddle .
 
"George Herold"

I was going to say it's a push-pull.... but it's flipped about.

Here's a pic
http://imageshack.us/photo/my-images/708/crossover.jpg/


** Than schem looks horribly familiar, maybe from the same idiot OP before.

It's the sort of thing you find repeated on many hobby sites that cannot
possibly work.

As drawn, it only works if the output transistors are biased for class A
operation PLUS it cannot possibly drive an 8 ohm load. 50 ohms might be
about the limit.

The twin rail splitters are an abortion.

Bias and load driving ability depend on the + DC rail voltage, which is not
shown.



.... Phil
 
On Thu, 12 Jan 2012 08:45:44 -0800 (PST), George Herold
<gherold@teachspin.com> wrote:

On Jan 11, 11:55 pm, "Phil Allison" <phi...@tpg.com.au> wrote:
"Bill Bowden"

I see excessive crossover distortion with this audio amp not shown
with LTspice. It simulates ok, but the wired circuit produces about a
50uS dead time step as the signal crosses the mid point. I tried
increasing the bias with no help. Both inputs to the op-amp look good
with no distortion. Any idea what is going on?

** You need to post a schematic  -  dickhead.

Totally  SMARTARSE of you to post only a Spice list on SEB.

...  Phil

I was going to say it's a push-pull.... but it's flipped about.

Here's a pic
http://imageshack.us/photo/my-images/708/crossover.jpg/

Does this output have a name?

George H.
Click to expand...
Unstable ?:)

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
On Fri, 13 Jan 2012 08:51:48 +1100, Phil Allison wrote:

"Fred Abse"
Phil Allison wrote:

** You need to post a schematic - dickhead.

Totally SMARTARSE of you to post only a Spice list on SEB.

What he posted *is* a schematic.


** Fuckwit, pedantic twaddle .
Click to expand...
Time to pretend you live in the same universe as the rest of us Phil, or
at least take your meds.

LTSpice schematics are text files, and that's what that was. I cut it
and pasted it into a text file and it worked _just fine_ in LTSpice.

Because it _is_ a schematic.

I'll leave the conclusions about what that says about _your_
intelligence, wit, and state of mind to the general audience.

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com
 
"Tim Wescott = FUCKING IDIOT "
"Fred Abse"
Phil Allison wrote:

** You need to post a schematic - dickhead.

Totally SMARTARSE of you to post only a Spice list on SEB.

What he posted *is* a schematic.


** Fuckwit, pedantic twaddle .

Time to pretend you live in the same universe as the rest of us Phil,
Click to expand...

** I do NOT live in the same narcissistic hell you do - pisshead.


LTSpice schematics are text files,
Click to expand...

** FFS - I want to see the **ORIGINAL** schematic.

That means a link to the site where the fuckwit OP got it.


Because it _is_ a schematic.
Click to expand...

** Absolute FUCKWIT INSANITY




..... Phil
 
"Bill Bowden = RETARD "



Yes, slew rate may be the problem. I was using a LM358


** ROTFLMAO.

Will this tenth wit moron never learn ANYTHING !!
 
On Jan 12, 11:18 am, Tim Wescott <t...@seemywebsite.com> wrote:

On Wed, 11 Jan 2012 20:14:05 -0800, Bill Bowden wrote:

I see excessive crossover distortion with this audio amp not shown with
LTspice. It simulates ok, but the wired circuit produces about a 50uS
dead time step as the signal crosses the mid point. I tried increasing
the bias with no help. Both inputs to the op-amp look good with no
distortion. Any idea what is going on?


If you look at the opamp output in the simulation you'll see that
it has
some near-vertical segments at crossover -- this means you're
working the
amp pretty hard, and it's an opportunity for Bad Things to happen.

Make sure that the slew rate, DC gain, and gain-bandwidth product
of your
"universal" op-amp matches the data sheet for what you're using.
 You may
want to check the real op-amp's output impedance, if it's even
listed.
If not, try tossing a 600 ohm resistor in series with your op-amp's
output, see what that does.

And take a look at your real op-amp output in your real circuit;
see what
it's doing.

Beyond that -- I dunno.
Click to expand...
Yes, slew rate may be the problem. I was using a LM358 which may not
be the best. I thought anything would work at audio freqs. The book
shows 10uS to move 3 volts into 2K with a 15 volt supply. The output
impedance also appears high since adding a 560 resistor in series with
the output doesn't change things much. The distortion is present at
the op-amp output and looks about the same as the main output.

The thing I don't understand is how the feedback signal from the
distorted output looks so good at the (+) input to the op-amp. It's a
10K resistor with a distorted waveform on one side and a clean signal
on the other.

-Bill
 
On Thu, 12 Jan 2012 18:12:59 -0800 (PST), George Herold
<gherold@teachspin.com> wrote:

On Jan 12, 7:27 pm, Jim Thompson <To-Email-Use-The-Envelope-I...@On-My-
Web-Site.com> wrote:
On Thu, 12 Jan 2012 08:45:44 -0800 (PST), George Herold





gher...@teachspin.com> wrote:
On Jan 11, 11:55 pm, "Phil Allison" <phi...@tpg.com.au> wrote:
"Bill Bowden"

I see excessive crossover distortion with this audio amp not shown
with LTspice. It simulates ok, but the wired circuit produces about a
50uS dead time step as the signal crosses the mid point. I tried
increasing the bias with no help. Both inputs to the op-amp look good
with no distortion. Any idea what is going on?

** You need to post a schematic  -  dickhead.

Totally  SMARTARSE of you to post only a Spice list on SEB.

...  Phil

I was going to say it's a push-pull.... but it's flipped about.

Here's a pic
http://imageshack.us/photo/my-images/708/crossover.jpg/

Does this output have a name?

George H.

Unstable ?:)

What's the 10k to the noninverting input about? There's an inversion
somehwere else in the circuit?

Bill, Since it's a single sided power supply a class A would be
easy... And less parts.

George H.
Click to expand...
I like "sliding" class-A... 1/2 the normal standby power.

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
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