On Jan 12, 7:27=A0pm, 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=A0pm, "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 =A0- =A0dickhead. > > >> Totally =A0SMARTARSE of you to post only a Spice list on SEB. > > >> ... =A0Phil > > >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.> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 ==A0 =A0 ...Jim Thompson> -- > | James E.Thompson, CTO =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 ==A0 =A0| =A0 =A0mens =A0 =A0 |> | Analog Innovations, Inc. =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 ==A0 | =A0 =A0 et =A0 =A0 =A0|> | Analog/Mixed-Signal ASIC's and Discrete Systems =A0| =A0 =A0manus =A0 ==A0|> | Phoenix, Arizona =A085048 =A0 =A0Skype: Contacts Only =A0| =A0 =A0 =A0 ==A0 =A0 =A0 |> | Voice:(480)460-2350 =A0Fax: Available upon request | =A0Brass Rat =A0| > | E-mail Icon athttp://www.analog-innovations.com| =A0 =A01962 =A0 =A0 | > > I love to cook with wine. =A0 =A0 Sometimes I even put it in the food.- H=ide quoted text -> > - Show quoted text -
Audio Amp Crossover Distortion?
Started by ●January 12, 2012
Reply by ●January 12, 20122012-01-12
Reply by ●January 12, 20122012-01-12
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. > >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.
Reply by ●January 12, 20122012-01-12
"George Herold" "Phil Allison" "George Herold"> > I was going to say it's a push-pull.... but it's flipped about. > > Here's a pichttp://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. >Yeah why not push-pull? Or if you want to do class A, use one pass element. ** FFS - class A push-pull output stages are very common and technically elegant. You know any electronics at all ? ... Phil
Reply by ●January 12, 20122012-01-12
"George Herold"
What's the 10k to the noninverting input about? There's an inversion
somehwere else in the circuit?
** FFS - the common emitter output stage inverts the signal.
You asleep ?
Reply by ●January 12, 20122012-01-12
On Jan 12, 9:30=A0pm, Jim Thompson <To-Email-Use-The-Envelope-I...@On-My- Web-Site.com> wrote:> On Thu, 12 Jan 2012 18:12:59 -0800 (PST), George Herold > > > > > > <gher...@teachspin.com> wrote: > >On Jan 12, 7:27=A0pm, 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=A0pm, "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 go=od> >> >> with no distortion. Any idea what is going on? > > >> >> ** You need to post a schematic =A0- =A0dickhead. > > >> >> Totally =A0SMARTARSE of you to post only a Spice list on SEB. > > >> >> ... =A0Phil > > >> >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? =A0There'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. > > I like "sliding" class-A... 1/2 the normal standby power.Hmm, never heard of sliding class-A, a JT invention? So I'll guess some outer control loop that senses the voltage and adjusts the bias. A second pass element? But it's gotta be fast. Is it load specific? George H.> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 ==A0 =A0 ...Jim Thompson> -- > | James E.Thompson, CTO =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 ==A0 =A0| =A0 =A0mens =A0 =A0 |> | Analog Innovations, Inc. =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 ==A0 | =A0 =A0 et =A0 =A0 =A0|> | Analog/Mixed-Signal ASIC's and Discrete Systems =A0| =A0 =A0manus =A0 ==A0|> | Phoenix, Arizona =A085048 =A0 =A0Skype: Contacts Only =A0| =A0 =A0 =A0 ==A0 =A0 =A0 |> | Voice:(480)460-2350 =A0Fax: Available upon request | =A0Brass Rat =A0| > | E-mail Icon athttp://www.analog-innovations.com| =A0 =A01962 =A0 =A0 | > > I love to cook with wine. =A0 =A0 Sometimes I even put it in the food.- H=ide quoted text -> > - Show quoted text -
Reply by ●January 12, 20122012-01-12
On Jan 12, 6:12=A0pm, George Herold <gher...@teachspin.com> wrote:> On Jan 12, 7:27=A0pm, 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=A0pm, "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 goo=d> > >> with no distortion. Any idea what is going on? > > > >> ** You need to post a schematic =A0- =A0dickhead. > > > >> Totally =A0SMARTARSE of you to post only a Spice list on SEB. > > > >> ... =A0Phil > > > >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 ?:-)> > =A0What's the 10k to the noninverting input about? =A0There's an inversio=n> 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. >A class A circuit wastes too much power. The idea was to get the highest output voltage with minimum battery drain. The output is common collector with a phase inversion between the op- amp and output, so the feedback connects to the (+) input for a gain of 11. The 120 ohm resistors are actually a combination of thermistors and resistors to solve the thermal stability problem. But as Tim said, the problem is probably slew rate. What op-amp would you recommend? -Bill
Reply by ●January 12, 20122012-01-12
"Bill Bowden= Imbecile " A class A circuit wastes too much power. ** Strange how you chose to use one then. The idea was to get the highest output voltage with minimum battery drain. ** The schem is 100% fucked. The output is common collector ** It's common emitter actually. The 120 ohm resistors are actually a combination of thermistors and resistors to solve the thermal stability problem. ** Which is impossible that way. The schem is 100% fucked - it cannot work. .... Phil
Reply by ●January 12, 20122012-01-12
On Jan 12, 7:12=A0pm, "Phil Allison" <phi...@tpg.com.au> wrote:> "Bill Bowden=3D =A0Imbecile " > > A class A circuit wastes too much power. > > ** Strange how you chose to use one then. > > The idea was to get the > highest output voltage with minimum battery drain. > > ** The schem is 100% fucked. > > The output is common collector > > ** It's common emitter actually. > > The 120 ohm resistors are actually a combination of thermistors > and resistors to solve the thermal stability problem. > > ** Which is impossible that way. > > =A0The schem is 100% fucked - =A0it cannot work. > > .... =A0PhilSo, why does it work in LTspice? Or did you even try it? -Bill
Reply by ●January 12, 20122012-01-12
"Bill Bowden" "Phil Allison"> "Bill Bowden= Imbecile " > > A class A circuit wastes too much power. > > ** Strange how you chose to use one then. > > The idea was to get the > highest output voltage with minimum battery drain. > > ** The schem is 100% fucked. > > The output is common collector > > ** It's common emitter actually. > > The 120 ohm resistors are actually a combination of thermistors > and resistors to solve the thermal stability problem. > > ** Which is impossible that way. > > The schem is 100% fucked - it cannot work. >So, why does it work in LTspice? ** The components are all idealised so impossible things happen in simulations. FFS - find another schem cos that one is NO FUCKING GOOD. And learn some damn electronics too. .... Phil
Reply by ●January 13, 20122012-01-13
On Jan 12, 10:07=A0pm, Bill Bowden <bper...@bowdenshobbycircuits.info> wrote:> On Jan 12, 6:12=A0pm, George Herold <gher...@teachspin.com> wrote: > > > > > > > On Jan 12, 7:27=A0pm, Jim Thompson <To-Email-Use-The-Envelope-I...@On-M=y-> > > 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=A0pm, "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 abou=t 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 g=ood> > > >> with no distortion. Any idea what is going on? > > > > >> ** You need to post a schematic =A0- =A0dickhead. > > > > >> Totally =A0SMARTARSE of you to post only a Spice list on SEB. > > > > >> ... =A0Phil > > > > >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 ?:-) > > > =A0What's the 10k to the noninverting input about? =A0There's an invers=ion> > 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. > > A class A circuit wastes too much power. The idea was to get the > highest output voltage with minimum battery drain. > > The output is common collector with a phase inversion between the op- > amp and output, so the feedback connects to the (+) input for a gain > of 11. The 120 ohm resistors are actually a combination of thermistors > and resistors to solve the thermal stability problem. > But as Tim said, the problem is probably slew rate. What op-amp would > you recommend? > > -Bill- Hide quoted text - > > - Show quoted text -I'm not that current on the latest opamps. But I use a lot of OPA134's (mostly dual 2134's) 20V/us slew rate. But a 'tad' more expensive than a LM358. What about a standard push-pull to save power.... or class D? (I never done a class D thing.) George H.
