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Capacitor Question

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  Capacitor Question Fabian Russell <root@localhost.localdomain> - 2015-11-03 22:14 +0000
    Re: Capacitor Question gilber34 <fafa@invalid.com> - 2015-11-03 16:35 -0600
      Re: Capacitor Question Fabian Russell <root@localhost.localdomain> - 2015-11-03 22:59 +0000
        Re: Capacitor Question gilber34 <fafa@invalid.com> - 2015-11-03 18:10 -0600
    Re: Capacitor Question jimp@specsol.spam.sux.com - 2015-11-03 22:47 +0000
      Re: Capacitor Question Fabian Russell <root@localhost.localdomain> - 2015-11-03 23:07 +0000
        Re: Capacitor Question jimp@specsol.spam.sux.com - 2015-11-03 23:20 +0000
          Re: Capacitor Question Fabian Russell <root@localhost.localdomain> - 2015-11-03 23:42 +0000
          Re: Capacitor Question Fabian Russell <root@localhost.localdomain> - 2015-11-04 02:49 +0000
            Re: Capacitor Question gilber34 <fafa@invalid.com> - 2015-11-03 21:40 -0600
              Re: Capacitor Question Fabian Russell <root@localhost.localdomain> - 2015-11-04 04:01 +0000
                Re: Capacitor Question jimp@specsol.spam.sux.com - 2015-11-04 06:03 +0000
                  Re: Capacitor Question Fabian Russell <root@localhost.localdomain> - 2015-11-04 07:07 +0000
                    Re: Capacitor Question jimp@specsol.spam.sux.com - 2015-11-04 20:29 +0000
                      Re: Capacitor Question Fabian Russell <root@localhost.localdomain> - 2015-11-04 20:51 +0000
                        Re: Capacitor Question jimp@specsol.spam.sux.com - 2015-11-04 21:08 +0000
                          Re: Capacitor Question Fabian Russell <root@localhost.localdomain> - 2015-11-04 21:53 +0000
                            Re: Capacitor Question jimp@specsol.spam.sux.com - 2015-11-04 22:20 +0000
                              Re: Capacitor Question Fabian Russell <root@localhost.localdomain> - 2015-11-04 22:42 +0000
                                Re: Capacitor Question jimp@specsol.spam.sux.com - 2015-11-04 23:07 +0000
                                  Re: Capacitor Question Fabian Russell <root@localhost.localdomain> - 2015-11-05 00:28 +0000
                                    Re: Capacitor Question jimp@specsol.spam.sux.com - 2015-11-05 00:46 +0000
                                  Re: Capacitor Question Fabian Russell <root@localhost.localdomain> - 2015-11-05 00:39 +0000
                                    Re: Capacitor Question jimp@specsol.spam.sux.com - 2015-11-05 00:58 +0000
                                Re: Capacitor Question benj <none@gmail.com> - 2015-11-04 18:25 -0500
                              Re: Capacitor Question benj <none@gmail.com> - 2015-11-04 18:37 -0500
                                Re: Capacitor Question Fabian Russell <root@localhost.localdomain> - 2015-11-05 00:09 +0000
                                  Re: Capacitor Question benj <nobody@gmail.com> - 2015-11-04 21:35 -0500
                                    Re: Capacitor Question gilber34 <fafa@invalid.com> - 2015-11-04 21:51 -0600
                                    Re: Capacitor Question Fabian Russell <root@localhost.localdomain> - 2015-11-05 04:19 +0000
                                      Re: Capacitor Question gilber34 <fafa@invalid.com> - 2015-11-05 11:10 -0600
                                        Re: Capacitor Question "reber g=emc^2" <herbertglazier0@gmail.com> - 2015-11-05 09:15 -0800
                                        Re: Capacitor Question Fabian Russell <root@localhost.localdomain> - 2015-11-05 18:08 +0000
                                      Re: Capacitor Question jimp@specsol.spam.sux.com - 2015-11-05 19:26 +0000
                                        Re: Capacitor Question Fabian Russell <root@localhost.localdomain> - 2015-11-05 19:44 +0000
                                          Re: Capacitor Question jimp@specsol.spam.sux.com - 2015-11-05 19:56 +0000
                                            Re: Capacitor Question Fabian Russell <root@localhost.localdomain> - 2015-11-05 20:53 +0000
                                            Re: Capacitor Question Fabian Russell <root@localhost.localdomain> - 2015-11-05 21:52 +0000
                        Re: Capacitor Question benj <none@gmail.com> - 2015-11-04 18:41 -0500
                          Re: Capacitor Question gilber34 <fafa@invalid.com> - 2015-11-04 21:54 -0600
            Re: Capacitor Question benj <nobody@gmail.com> - 2015-11-04 02:17 -0500
              Re: Capacitor Question Fabian Russell <root@localhost.localdomain> - 2015-11-04 07:30 +0000
                Re: Capacitor Question gilber34 <fafa@invalid.com> - 2015-11-04 07:48 -0600
                Re: Capacitor Question benj <nobody@gmail.com> - 2015-11-04 14:04 -0500
                  Re: Capacitor Question Fabian Russell <root@localhost.localdomain> - 2015-11-04 19:28 +0000
                    Re: Capacitor Question benj <none@gmail.com> - 2015-11-04 18:49 -0500
                      Re: Capacitor Question gilber34 <fafa@invalid.com> - 2015-11-04 20:41 -0600
                        Re: Capacitor Question Fabian Russell <root@localhost.localdomain> - 2015-11-05 03:16 +0000
                          Re: Capacitor Question gilber34 <fafa@invalid.com> - 2015-11-04 21:58 -0600
            Re: Capacitor Question "reber g=emc^2" <herbertglazier0@gmail.com> - 2015-11-04 12:14 -0800
              Re: Capacitor Question benj <none@gmail.com> - 2015-11-04 18:44 -0500
                Re: Capacitor Question gilber34 <fafa@invalid.com> - 2015-11-04 20:41 -0600
    Re: Capacitor Question gyansorova@gmail.com - 2015-11-05 16:34 -0800

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#530459

On Wed, 04 Nov 2015 23:07:30 +0000, jimp wrote:

> 
> The way to fix the problem is to first measure what the load, i.e. the
> headphone and all the cable, presents to the amplifier.
> 

Correct.  But trial and error can be effective as well.

I had a similar problem once before.  I used a home-built 50 Watt
amplifier to power some home-built speakers on very long leads.
There was never any problem.

However, one day I hooked up some commercial speakers (older ones
I had in storage) and above a certain output level oscillations
would occur.  I placed some high current inductors between output
and load and the problem was solved.

I strongly suspect that a simple filter between output and load
will do the trick in solving my latest issue as well.













> Then build a spice model of the amplifier with the load and run a
> transit analysis.
> 
> That should tell you what you need to do.
> 
> Decades ago I was involved in the development of wire guided torpedoes.
> 
> When tested, guidance always failed.
> 
> Long story short, the actual impedance of the load as the wire spooled
> out was measured and found to be a complex spiral when plotted on a
> Smith chart. The driver amplifier had to be totally redesigned to drive
> that load.

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#530466

Fabian Russell <root@localhost.localdomain> wrote:
> On Wed, 04 Nov 2015 23:07:30 +0000, jimp wrote:
> 
>> 
>> The way to fix the problem is to first measure what the load, i.e. the
>> headphone and all the cable, presents to the amplifier.
>> 
> 
> Correct.  But trial and error can be effective as well.

And an infinate number of monkeys on an infinate number of keyboards
will eventually write The Taming of the Shrew.

> I had a similar problem once before.  I used a home-built 50 Watt
> amplifier to power some home-built speakers on very long leads.
> There was never any problem.
> 
> However, one day I hooked up some commercial speakers (older ones
> I had in storage) and above a certain output level oscillations
> would occur.  I placed some high current inductors between output
> and load and the problem was solved.
> 
> I strongly suspect that a simple filter between output and load
> will do the trick in solving my latest issue as well.

That is known as the BFFI approach.


-- 
Jim Pennino

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#530462

On Wed, 04 Nov 2015 23:07:30 +0000, jimp wrote:

> 
> Sounds like an irrational fear of RF to me.
> 

Actually, cable connections are always far more robust
than an RF connection could ever be.

The philosophy is simple.  Just stick with cable and you'll
NEVER experience the subtle and not so subtle problems that
can arise with RF.

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#530467

Fabian Russell <root@localhost.localdomain> wrote:
> On Wed, 04 Nov 2015 23:07:30 +0000, jimp wrote:
> 
>> 
>> Sounds like an irrational fear of RF to me.
>> 
> 
> Actually, cable connections are always far more robust
> than an RF connection could ever be.

For piping music to headphones, robust has no meaning.

> The philosophy is simple.  Just stick with cable and you'll
> NEVER experience the subtle and not so subtle problems that
> can arise with RF.

And with RF you will NEVER experience the subtle and not so subtle problems
that can arise with 50 feet of cable and connectors.

 

-- 
Jim Pennino

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#530436

On 11/04/2015 05:42 PM, Fabian Russell wrote:
> On Wed, 04 Nov 2015 22:20:00 +0000, jimp wrote:
>
>>
>> buy a set of wireless
>> stereo headphones
>>
>
> Not me.  I am philosophically opposed to wireless devices.
>
> I have no wireless mouse, no wireless keyboard, no wireless router,
> etc., etc.
>
> For me, the signal has got to be in the cable and only in the cable.
>
> It's called a human factor.  It may be irrational, but it is also
> incontrovertible.
>
> But as regards the problem, I'll fix it, eventually.

Hey, FR if you aren't doing anything opposed to those in power you don't 
need to worry about them keeping tabs on you! Love BB.



-- 

       ___           ___           ___            ___
      /\  \         /\  \         /\__\          /\  \
     /::\  \       /::\  \       /::|  |         \:\  \
    /:/\:\  \     /:/\:\  \     /:|:|  |     ___ /::\__\
   /::\~\:\__\   /::\~\:\  \   /:/|:|  |__  /\  /:/\/__/
  /:/\:\ \:|__| /:/\:\ \:\__\ /:/ |:| /\__\ \:\/:/  /
  \:\~\:\/:/  / \:\~\:\ \/__/ \/__|:|/:/  /  \::/  /
   \:\ \::/  /   \:\ \:\__\       |:/:/  /    \/__/
    \:\/:/  /     \:\ \/__/       |::/  /
     \::/__/       \:\__\         /:/  /
      ~~            \/__/         \/__/

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#530441

On 11/04/2015 05:20 PM, jimp@specsol.spam.sux.com wrote:
> Fabian Russell <root@localhost.localdomain> wrote:
>> On Wed, 04 Nov 2015 21:08:53 +0000, jimp wrote:
>>
>>>
>>> Right, which is why you spend close to $100 for one capacitor.
>>>
>>
>> That's not me.  That's benj the thrifty shopper.  He couldn't rival
>> the average housewife in terms of financial prudence.
>>
>> But maybe you help with this one.
>>
>> I have an audio power amplifier built with discrete PNP (or is it NPN?)
>> transistors. (Yes, they still make them in droves.)
>>
>> The design uses two transistors in a "mirror image" configuration with
>> one to handle the positive swings and the other to handle the negative
>> swings (there is a name for this config but I can't recall what it is).
>> There are some extra parts to cancel the bias currents and other things
>> but the design is nothing more than that.
>>
>> It performs very well with no distortion whatsoever.
>>
>> Now I use this amp to power my headphones, although it can kick out
>> a lot more power if needed.
>>
>> I need music to help me with my workouts on my exercise machines,
>> thus I have the amp right next to my machine in the basement.
>> The headphones are attached to the amp with about 10 feet of
>> audio cable.
>>
>> I have another exercise machine on the first floor.  Rather than
>> carry the amp up from basement to first floor and back again, I
>> decided to run about 50 feet of audio cable from the basement amp
>> to the headphones on the first floor (the distance is not quite 50 feet
>> but it always better to have a little more than less).
>>
>> So everything is the same, except for an extra 40 feet of audio
>> cable between amp and headphones (1K ohm input impedance).
>>
>> However, when I switched on the power and output, a fuse on one
>> rail of the power supply blew out after a few seconds -- and these
>> are 2 amp fuses!
>>
>> What is happening?
>>
>> I could put an oscilloscope on the output and observe what happens
>> but I don't want to blow another fuse -- and possibly mess up my
>> circuit.
>>
>> I strongly suspect that the extra cable length is somehow inducing
>> oscillations at some supra-audio frequency and these oscillations
>> are drawing a lot of current from the supply.
>>
>> So how can I fix it?
>>
>> How about a nice choke (inductor) on the output?
>
> If it is oscillating it is likely that your amplifier does not like
> inductive loads, i.e. all that cable, so adding an inductor will probably
> just make it worse.
>
> If it were me, I would shit can all that wire and buy a set of wireless
> stereo headphones, which can be had for well under $50 these days.

When FR says "audio cable" does he mean coaxial cable?  I hope not as 
that would have lots of capacitance and as you say can destabilize the 
feedback of the amp causing it oscillate as you said.

Why he thinks that using a scope is going to cause it to blow up is as 
big a mystery as his cap pricing.

Anyway, for anyone working in electronics all you need to know is the 
rule: Transistors make MUCH better fuses than fuses.

Fabian, just go on line and order the proper NPN and PNP transistors for 
your output stage (actually more likely search around to find out who is 
currently making similar replacement transistors for the ones actually 
used which are no longer made). Just replace them all. You can test them 
later or not. Amp should come back to life. A decent amp should easily 
drive 50 feet of lamp cord. Oh wait! You built this
-- 

       ___           ___           ___            ___
      /\  \         /\  \         /\__\          /\  \
     /::\  \       /::\  \       /::|  |         \:\  \
    /:/\:\  \     /:/\:\  \     /:|:|  |     ___ /::\__\
   /::\~\:\__\   /::\~\:\  \   /:/|:|  |__  /\  /:/\/__/
  /:/\:\ \:|__| /:/\:\ \:\__\ /:/ |:| /\__\ \:\/:/  /
  \:\~\:\/:/  / \:\~\:\ \/__/ \/__|:|/:/  /  \::/  /
   \:\ \::/  /   \:\ \:\__\       |:/:/  /    \/__/
    \:\/:/  /     \:\ \/__/       |::/  /
     \::/__/       \:\__\         /:/  /
      ~~            \/__/         \/__/

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#530457

On Wed, 04 Nov 2015 18:37:10 -0500, benj wrote:

> 
> When FR says "audio cable" does he mean coaxial cable?
>

When I say "audio cable" I mean audio cable.  Is that supposed
to be a surprise?

Audio cable has three strands surrounded by a metal foil shield.
I could use lamp cord but it only has two strands and so I'd need
to double the length.  Besides, I  just happened to have an unused
spool of audio cable inside my junk box.  Since I could foresee
no other need, I decided to use what I had.

>
> Why he thinks that using a scope is going to cause it to blow up is as 
> big a mystery as his cap pricing.
> 

Can't you read?  To test the circuit with an oscilloscope, I would
need to duplicate the same conditions that caused a 2 amp fuse to
blow.  This means the fuse would certainly blow again.  This would
be foolish since, for all I know, the next time around may damage
the circuit.

In the engineering trade, this is known as destructive testing.


>
> A decent amp should easily 
> drive 50 feet of lamp cord. Oh wait! You built this
>

The story is actually a bit more convoluted, but I will spare the world
the extra details.

I haven't the wherewithal at the moment to delve deeper, but
I'll get there, eventually.

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#530476

On 11/04/2015 07:09 PM, Fabian Russell wrote:
> On Wed, 04 Nov 2015 18:37:10 -0500, benj wrote:
>
>>
>> When FR says "audio cable" does he mean coaxial cable?
>>
>
> When I say "audio cable" I mean audio cable.  Is that supposed
> to be a surprise?
>
> Audio cable has three strands surrounded by a metal foil shield.
> I could use lamp cord but it only has two strands and so I'd need
> to double the length.  Besides, I  just happened to have an unused
> spool of audio cable inside my junk box.  Since I could foresee
> no other need, I decided to use what I had.

Ah! Cheap-ass intercom cable. Gotcha!  Otherwise known as a roll of 
linear capacitor...


>> Why he thinks that using a scope is going to cause it to blow up is as
>> big a mystery as his cap pricing.
>>
>
> Can't you read?  To test the circuit with an oscilloscope, I would
> need to duplicate the same conditions that caused a 2 amp fuse to
> blow.  This means the fuse would certainly blow again.  This would
> be foolish since, for all I know, the next time around may damage
> the circuit.
>
> In the engineering trade, this is known as destructive testing.

In the engineering trade people use scopes to learn what is going on 
without (usually) blowing things up. If you took out a fuse and did NOT 
take out the output transistors I would be VERY surprised.

>> A decent amp should easily
>> drive 50 feet of lamp cord. Oh wait! You built this
>>
>
> The story is actually a bit more convoluted, but I will spare the world
> the extra details.
>
> I haven't the wherewithal at the moment to delve deeper, but
> I'll get there, eventually.
>


-- 
         ___           ___           ___            ___
        /\  \         /\  \         /\__\          /\  \
       /::\  \       /::\  \       /::|  |         \:\  \
      /:/\:\  \     /:/\:\  \     /:|:|  |     ___ /::\__\
     /::\~\:\__\   /::\~\:\  \   /:/|:|  |__  /\  /:/\/__/
    /:/\:\ \:|__| /:/\:\ \:\__\ /:/ |:| /\__\ \:\/:/  /
    \:\~\:\/:/  / \:\~\:\ \/__/ \/__|:|/:/  /  \::/  /
     \:\ \::/  /   \:\ \:\__\       |:/:/  /    \/__/
      \:\/:/  /     \:\ \/__/       |::/  /
       \_:/__/       \:\__\         /:/  /
                      \/__/         \/__/

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#530497

On 11/4/2015 8:35 PM, benj wrote:
> On 11/04/2015 07:09 PM, Fabian Russell wrote:
>> On Wed, 04 Nov 2015 18:37:10 -0500, benj wrote:
>>
>>>
>>> When FR says "audio cable" does he mean coaxial cable?
>>>
>>
>> When I say "audio cable" I mean audio cable.  Is that supposed
>> to be a surprise?
>>
>> Audio cable has three strands surrounded by a metal foil shield.
>> I could use lamp cord but it only has two strands and so I'd need
>> to double the length.  Besides, I  just happened to have an unused
>> spool of audio cable inside my junk box.  Since I could foresee
>> no other need, I decided to use what I had.
>
> Ah! Cheap-ass intercom cable. Gotcha!  Otherwise known as a roll of
> linear capacitor...

which is excellent copper,
the only thing "cheap" is the plastic.
I use it on my low power speakers too, it is a good choice.

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#530502

On Wed, 04 Nov 2015 21:35:29 -0500, benj wrote:
 
>
> If you took out a fuse and did NOT 
> take out the output transistors I would be VERY surprised.
> 

Well, be surprised.  These are 2N3055 transistors and they can
handle a LOT of current.  They are excellent for the audio range
and very cheap. 

Actually, I blew THREE fuses before I realized that something
was amiss.

The fuses were fast-blow, and they were doing their job in protecting
the circuit.  If I had used slow-blow fuses, then MAYBE some damage
would have occurred, but not likely. 

Only one of two fuses blew, however.

The amp is a "push-pull" design.  It has two power rails, positive
and negative, of equal magnitude.  Only one rail (I forget which)
caused the fuse blow.

But I can say little else because I am not fiddling with a potentially
damaging situation by playing detective.  A filter will do the job.

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#530549

On 11/4/2015 10:19 PM, Fabian Russell wrote:
> On Wed, 04 Nov 2015 21:35:29 -0500, benj wrote:
>
>>
>> If you took out a fuse and did NOT
>> take out the output transistors I would be VERY surprised.
>>
>
> Well, be surprised.  These are 2N3055 transistors and they can
> handle a LOT of current.  They are excellent for the audio range
> and very cheap.

> Actually, I blew THREE fuses before I realized that something
> was amiss.

> The fuses were fast-blow, and they were doing their job in protecting
> the circuit.  If I had used slow-blow fuses, then MAYBE some damage
> would have occurred, but not likely.
>
> Only one of two fuses blew, however.
>
> The amp is a "push-pull" design.  It has two power rails, positive
> and negative, of equal magnitude.  Only one rail (I forget which)
> caused the fuse blow.
>
> But I can say little else because I am not fiddling with a potentially
> damaging situation by playing detective.  A filter will do the job.
>

ran across a part: SSM2142 it takes single ended audio and drives it 
balanced on a long line, very low distortion.  From a Turntable via 50 
foot cable to headphones (?)  Had not really seen a hifi analog cable 
driver, most all are digital.

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#530551

On Thursday, November 5, 2015 at 9:10:59 AM UTC-8, gilber34 wrote:
> On 11/4/2015 10:19 PM, Fabian Russell wrote:
> > On Wed, 04 Nov 2015 21:35:29 -0500, benj wrote:
> >
> >>
> >> If you took out a fuse and did NOT
> >> take out the output transistors I would be VERY surprised.
> >>
> >
> > Well, be surprised.  These are 2N3055 transistors and they can
> > handle a LOT of current.  They are excellent for the audio range
> > and very cheap.
> 
> > Actually, I blew THREE fuses before I realized that something
> > was amiss.
> 
> > The fuses were fast-blow, and they were doing their job in protecting
> > the circuit.  If I had used slow-blow fuses, then MAYBE some damage
> > would have occurred, but not likely.
> >
> > Only one of two fuses blew, however.
> >
> > The amp is a "push-pull" design.  It has two power rails, positive
> > and negative, of equal magnitude.  Only one rail (I forget which)
> > caused the fuse blow.
> >
> > But I can say little else because I am not fiddling with a potentially
> > damaging situation by playing detective.  A filter will do the job.
> >
> 
> ran across a part: SSM2142 it takes single ended audio and drives it 
> balanced on a long line, very low distortion.  From a Turntable via 50 
> foot cable to headphones (?)  Had not really seen a hifi analog cable 
> driver, most all are digital.

Thick wire is best especially for DC  TreBert

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#530562

On Thu, 05 Nov 2015 11:10:40 -0600, gilber34 wrote:


> 
> ran across a part: SSM2142 it takes single ended audio and drives it 
> balanced on a long line, very low distortion.
>

What this part does is convert a signal from balanced to unbalanced.

An unbalanced line is useful for noise immunity:

http://www.aviom.com/blog/balanced-vs-unbalanced

But in my situation it wouldn't really apply because I use
unbalanced lines throughout the system.

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#530585

Fabian Russell <root@localhost.localdomain> wrote:
> On Wed, 04 Nov 2015 21:35:29 -0500, benj wrote:
>  
>>
>> If you took out a fuse and did NOT 
>> take out the output transistors I would be VERY surprised.
>> 
> 
> Well, be surprised.  These are 2N3055 transistors and they can
> handle a LOT of current.  They are excellent for the audio range
> and very cheap. 
> 
> Actually, I blew THREE fuses before I realized that something
> was amiss.
> 
> The fuses were fast-blow, and they were doing their job in protecting
> the circuit.  If I had used slow-blow fuses, then MAYBE some damage
> would have occurred, but not likely. 
> 
> Only one of two fuses blew, however.
> 
> The amp is a "push-pull" design.  It has two power rails, positive
> and negative, of equal magnitude.  Only one rail (I forget which)
> caused the fuse blow.
> 
> But I can say little else because I am not fiddling with a potentially
> damaging situation by playing detective.  A filter will do the job.

What exactly are you going to filter if it is the amplifier oscillating? 

-- 
Jim Pennino

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#530592

On Thu, 05 Nov 2015 19:26:07 +0000, jimp wrote:

> 
> What exactly are you going to filter if it is the amplifier oscillating?
>

Well, the amp is oscillating because of the impedance characteristics
of the load.

Placing some extra components as part of the load will modify those
characteristics and prevent the oscillations.  This is what I mean
by a "filter."

First I have to determine the nature of the oscillations and the
frequency in particular.

This task is on the back-most back burner at the moment.  I'll
get to it -- eventually.

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#530595

Fabian Russell <root@localhost.localdomain> wrote:
> On Thu, 05 Nov 2015 19:26:07 +0000, jimp wrote:
> 
>> 
>> What exactly are you going to filter if it is the amplifier oscillating?
>>
> 
> Well, the amp is oscillating because of the impedance characteristics
> of the load.
> 
> Placing some extra components as part of the load will modify those
> characteristics and prevent the oscillations.  This is what I mean
> by a "filter."

The rest of the world would call that a snubber.

> First I have to determine the nature of the oscillations and the
> frequency in particular.

The phrase "nature of the oscillations" is meaningless, but if the
frequency is above the audio range it means you need to roll off the
amplifier high frequency gain.

> This task is on the back-most back burner at the moment.  I'll
> get to it -- eventually.
> 

-- 
Jim Pennino

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#530607

On Thu, 05 Nov 2015 19:56:29 +0000, jimp wrote:

> 
> but if the
> frequency is above the audio range it means you need to roll off the
> amplifier high frequency gain.
> 

I'll look into that -- eventually.

I don't know what is going on.  Along with actual music, I can hear loud
pops and crackles in the headphones which sounds like the strong inference
from a motor or auto ignition noise.

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#530616

On Thu, 05 Nov 2015 19:56:29 +0000, jimp wrote:

> 
> but if the
> frequency is above the audio range it means you need to roll off the
> amplifier high frequency gain.
> 

What I find possibly strange is that under normal circumstances (i.e when
there is no problem) I have the headphones attached to the amp through
an approx. 10 foot audio cable.  But this cable is of the tightly coiled
variety, similar to those found on telephone handsets.  I would be surprised
if this cable would no reach close to 50 ft. if stretched out to the max.
Yet this cable causes no problem.  Maybe it's not shielded.

  

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#530443

On 11/04/2015 03:51 PM, Fabian Russell wrote:
> On Wed, 04 Nov 2015 20:29:44 +0000, jimp wrote:
>
>>
>> It seems you are a staunch believer in the BAC (Big Ass Capacitor) method
>> of filter design.
>>
>
> Nope.  Just big enough to do the job.  For my power supplies I use 2200uF @ 25V,
> 1000uF @20V, etc. etc.
>
> In fact, when all specs for a linear supply are considered, my caps follow
> the Goldilocks principle: not too big, not too small, but just right.
>
>
>>
>> If you do the analysis,
>>
>
> I don't need no analysis.  I just put an oscilloscope on the output
> and watch as everything stays perfectly flat with various loads.
>
> Power supplies are quite trivial and not worth diddling over.
>
> I save my in-depth analysis for the circuits that are powered by them.

Nonsense, Fabio!  Don't you ever read any of the mags for high end 
Audiophile gear?  Without a $300 power cord that amp will never 
reproduce any music with the proper "sheen"! It's all about attention to 
the smallest detail!



-- 

       ___           ___           ___            ___
      /\  \         /\  \         /\__\          /\  \
     /::\  \       /::\  \       /::|  |         \:\  \
    /:/\:\  \     /:/\:\  \     /:|:|  |     ___ /::\__\
   /::\~\:\__\   /::\~\:\  \   /:/|:|  |__  /\  /:/\/__/
  /:/\:\ \:|__| /:/\:\ \:\__\ /:/ |:| /\__\ \:\/:/  /
  \:\~\:\/:/  / \:\~\:\ \/__/ \/__|:|/:/  /  \::/  /
   \:\ \::/  /   \:\ \:\__\       |:/:/  /    \/__/
    \:\/:/  /     \:\ \/__/       |::/  /
     \::/__/       \:\__\         /:/  /
      ~~            \/__/         \/__/

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#530499

On 11/4/2015 5:41 PM, benj wrote:
> On 11/04/2015 03:51 PM, Fabian Russell wrote:
>> On Wed, 04 Nov 2015 20:29:44 +0000, jimp wrote:
>>

>> I don't need no analysis.  I just put an oscilloscope on the output
>> and watch as everything stays perfectly flat with various loads.
>>
>> Power supplies are quite trivial and not worth diddling over.
>>
>> I save my in-depth analysis for the circuits that are powered by them.
>
> Nonsense, Fabio!  Don't you ever read any of the mags for high end
> Audiophile gear?  Without a $300 power cord that amp will never
> reproduce any music with the proper "sheen"! It's all about attention to
> the smallest detail!
>

so true, and the Audio cables to Speakers must have gold connectors and 
cost $20 per foot to preserve those unhearable notes, at very loud volume.

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