[ppl]

what do you like or dislike about audio amplifiers that use no coupling capacitors

 

[PeterR]

If the amp is suitable for direct coupling, the best cap is no cap...

 

[Budgie]

In signal paths, the best cap is no cap. No doubt about it.

If you must use a cap, the cap that sounds closest to no cap is a Polyproplene in oil.

Most of the "audiophile" speciality caps are a massive rip-off of your money.

 

[JohnFerrier]

Well, I was worried with my discrete amp at first with no voltage regulators. I'm using batteries and was concered about them drainging at different rates. Then I connected +9V and -18V...no offset problem. Then, +18V and -9V...no problem : ). Still, kind of surprises me. The batteries do seem to drain at the same rate though...that part makes sense.

Like the poll choices.


JF

 

[tangent]

Quote:

+18V and -9V...no problem : ). Still, kind of surprises me

Try 0.5V and 9V.

 

[JohnFerrier]

Actually, accidently I had it hooked up +9V and 0V. The output was something like 0.5V no load. Don't think that would kill 300 ohm headphones... I'll be using circuitry to monitor the battery levels...


JF

 

[rickcr42]

I have no problem with either topology ,just absolutes

when i was a much younger man i was easily swayed by equipment advertising where the manufacturer would make an argument for this or that and after reading the ad copy would say to myself "OK.That makes perfect sense"

then and sell off my gear and purchase the latest and greatest

I should have my behind whipped for selling some great sounding gear and replacing it with crap because it was "scientifically correct" according to that years BIG THING

Correct maybe ,but still sounded like crap !

DC coupled can be great or it can be crap

AC coupled the same

I don't care how i get there as long as the ride is a good one

 

[rickcr42]

I added a category , hope you don't mind

but there was nothing i could vote on there being no absolutes in audio or in life

 

[Demolition]

I voted "DC Coupling Rules", but only insofar as it provides good low frequency response and is an example of the old adage "simpler is better".

Otherwise, as Rick said, whatever works in a given situation is good enough for me.

D.

 

[Sal]

With plenty of really good audio caps to choose from, I don't think it generally hurts the sound quality significantly to use coupling caps. Depending on the caps, they may even color the sound and you may end up with an amp that sounds just a bit different than your others.

Let's be serious here, what fun would it be to build several amps that all sounded equally transparent? I think that part of the DIY addiction is to have different amps that suit different uses and moods.

 

[averydonovan]

It depends on the use. If I am building an amp for my own sources which I know are DC offset safe then I leave out the coupling cap since I'd like leave the signal path as clean as possible. I figure the fewer the components, the better. But if I was going to use an amp I build with a variety of sources that I don't own that may have DC offset then I'd rather put in the coupling caps rather than risk frying an expensive set of headphones. For the last year or so I have not had coupling caps in any amps I've built so I haven't really had any time to compare the same circuit with and without the coupling caps so I can't say what's better.

 

[PeterR]

Quote:

Originally posted by Sal With plenty of really good audio caps to choose from, I don't think it generally hurts the sound quality significantly to use coupling caps. Depending on the caps, they may even color the sound and you may end up with an amp that sounds just a bit different than your others. Let's be serious here, what fun would it be to build several amps that all sounded equally transparent? I think that part of the DIY addiction is to have different amps that suit different uses and moods.

To each his own, I guess. For me it's much more fun to try to get as close as possible to the sound of the original event (or at least to what's on the recordings, obviously that's what we're limited to). Call me old fashioned, but I actually prefer the sound of real instruments to colorations.

 

[rickcr42]

Quote:

Call me old fashioned, but I actually prefer the sound of real instruments to colorations.

the hard part is : how do we know what the original sounds like ?

I do a lot of live performances so i have a benchmark but most only know recorded music unless it is electrified instruments and have no clue what an actual acoustic instrument sounds like

If you listen to the same Cd on two different systems it will be recognizable as the same performer but no way it sounds the same

the sound will even be different according to which headphones or speakers are used

All we can do is determine what we think approximates what we personally hear live

and as stated before : for me it is the dynamic contrast and retreival of low level detail more than the tone that determines good sound.

That and the overtones and a natural decay rather than an abrupt ending to the music

Unless the cap smears the notes it has no bearing on the performance-just the tone and said tone could have sounded entirely different to the engineer depending on what was used for the final mix.

and if live the tone is very "venue" dependant - size ,absorption,inside vs outside ,how far the side or back walls are from the performers ,duration of echo or lack of

all of these factors can and do make the same instrument sound entirely different

Not that we will ever be fooled into thinking we are "there" but get drum dynamics and piano right and you can pretty much know you are capable of reproducing music .

After that it comes down to taste and there i listen to the human voice to get the "flavor" of the gear

So let's see ,

I like efficient loudspeakers/headphones that get moving with very little effort allowing the softest passages to be heard ,but not lost in the self noise of the circuit , the noise floor MUST be lower than the softest notes

And the amp/transducer must have enough left over to reproduce sudden peaks with speed and authority - no compression or other abbrerations

And finally the tone must be pleasing but not so much that a bad recording is sugar coated and made to sound good

the last is a tough one 'cause again ,i have no clue what the engineer was thinking

but quick story/analogy-


i have had fairly decent audio gear since my early "muddled" twenties

i may have had some ratty cars and maybe needed a haircut back then but my music came first and that is where i put my hard earned loot .

And there were always certain albums or individual songs from those albums that were damn near unlistenable

Unlike the convenience of the CD a phono disc does not have a "skip" control so if after a good song the next was crap you had to get up and cue the disc to avoid the "bad song"

I always wondered why in the hell someone who obviously got payed to make the record could be so dumb as to allow this engineer to screw it up so bad !

What the *&$%% ?

The guy on drugs ?

Then i would hear the same cut on the radio and it would be fine !!!!

Now i was really confused

How could a POS radio beat my big dollar system ?

I reasoned that since I KNEW my system was more accurate than the radio that i was just showing the flaws in the medium .Flaws the radio could not resolve so what i was hearing was correct and what the "masses" were hearing was an approximation of the cut with the low-fi electronics glossing over and sugar coating the flaws.

And when upon hearing another system where that same song sounded great but looking at the componants and adding up the cost I would reason that person was not hearing the actual recording but was FOOLING his/herself and my system was actually superior and allowed me to hear what was actually there.

So while this jerkweed was enjoying music i was jumping for the cuing lever and "HE" was wrong by "I" was right.

afterall ,i read all the high end audio magazines and "I" payed attention to all the AES copy and the "newest ,bestest,gottahavitist" gear ads made perfect sense to me .

And i was fooling myself .

I still pull out cuts that i thought were unlistenable and

JEEZ THAT SOUNDS GOOD !

Hell ,i even managed to get James Gangs "Funk 49" to sound like there is some serious note separation going on (there is !) and not just a wall of sound !

Jefferson Airplane "Volunteers" actually has a dynamic range !

!

what's goin' on here !

Maybe the engineer knew what he was doing after all and it was me not getting it !

By being stubborn and elitist all those years i missed out on some great music .

I "knew" what i needed to reproduce good sound in the home but what i knew was wrong .

I was more into the gear than the music and by always upgrading in search of "accuracy at any cost" i missed out !

I lost a lot of time that would have been better spent listening to the radio where at least the music was enjoyable for what it was instead of being know it all and stubbornly sticking to my conceptions

I gave up a lot of good equipment over the years because it was "not right" .

It was not up to what the experts said was the way to nirvana

Tone controls in the signal path ?

[size=small]NO NO NO NO ![/size]

Audio Death and a signal butcher !

so i went without ,even though i missed the hell out of my "loudness" control.

I told myself it was more "accurate" that way and either strained to hear the low notes or turned it up at three AM after patrolling the local clubs .

Of course the neighbors did not appreciate it too much.

They did not have my stamina and actually needed SLEEP before going to work !

Headphones were out ,they all sucked ,so it was 95dbs at 3AM or nothing

I have come full circle

Tone controls or not but available

AC coupling or not

Tubes ,transistors,hybrids

Class A , class AB

My loudspeakers actually look like crap according to the specs but sound great with ALL music

someone used the ferrari analogy :

Paraphrasing "why drive a XXXXX when you can get there in a ferrari"

Because why the ferrari is in the shop always being tuned to be at its best my behind will be getting from point A to point B

The ride may not look as "hot" but mechanically it is a sound ride and in the end it is not how you get there as long as you arrive at the destination in some comfort

I gave up on trying to be correct and learned how to enjoy music again

caps and all

 

[PeterR]

You don't expect me to read all that, do you?

I know it's a strange concept and don't need nor expect everybody to get it. My idea of fun is the sound of the real thing, and I enjoy any tiny little small step that gets me closer to that goal. Colorations added by the components can be exciting at first, but to me over time that will become boring because everything you play through such a system sounds the same in some way. So in the end you're listening to your gear and not to the music, and if you've grown tired of it you need new gear with a different flavour to get your new fix. Hmm, if that isn't being "more into the gear than the music and by always upgrading" then what is?

Has got nothing to do with snobbery. This is just me, and I certainly won't look down on people aspiring to different goals (and I'm somewhat sorry I got started about this in the first place).
Bottom line, do whatever floats your boat and be happy with it. I don't need anybody to tell me what to enjoy, and I'm not to tell anybody what he should enjoy... .

 

[rickcr42]

Quote:

You don't expect me to read all that, do you?

you think that was easy to put down man ?

Quote:

I know it's a strange concept and don't need nor expect everybody to get it. My idea of fun is the sound of the real thing, and I enjoy any tiny little small step that gets me closer to that goal.

and for me , the "getting closer to the music" is simplifying the signal path . Getting rid off all the extra stages and servos and using a single cascoded device coupled to a single capacitor if needed.

simple,clean and does not get in the way of the music

Quote:

Colorations added by the components can be exciting at first, but to me over time that will become boring because everything you play through such a system sounds the same in some way.

who says the part has to have "colorarions" that must be innaccurate ?

every single part in the audio signal chain has a "sound" and not all are good nor are they inherently bad

Make a DC coupled amp with edgy sounding el cheapo metal film resistors and the end sound will be far worse than any that a single cap could be

Quote:

Hmm, if that isn't being "more into the gear than the music and by always upgrading" then what is?

and if you HAD read the entirety of my post , not an easy task i know

you will read where i did the formewr in my youth and no longer am as much of a "gear head' as i am a music listener

a listener that uses the live performance as my benchmark

i actually get out of the house and sample the real thing and not hide away in the basement trying to reconstruct something i have no knowledge of

Quote:

Has got nothing to do with snobbery. This is just me, and I certainly won't look down on people aspiring to different goals (and I'm somewhat sorry I got started about this in the first place).

\
same goals ,different methods

to say that someone who uses AC coupling is not looking for accurate sound covers way too much ground and eliminmates some exellant audio equipment from contention

DC at any cost ?

Some would say a servo does far more damge than any single cap could ever do

are they right and you wrong ?

am i ?

There is no correct method just correct implementation for need

you can break down a simple circuit into stages and see where decisions are made at each point

bandwidth ,bias points ,voltage/current drive

i would build a different circuit for a simple gain stage than i would if i were trying to drive thirty feet of cable to a remote amp.

just common sense

would the long line driver also work for a run of two feet ?

Of course !

but optimized to the application it would not be !

again it comes down to application

And most likely i would use a balanced transformer which REALLY gets the anti capacitor

You can actually see the blood rising to thier cheeks ! crews panties bunched up !

there is no one size fits all or there would be one amp for everyone and we could shut down the DIY forum and just listen to music ,not a bad thing

music being the end goal

Quote:

Bottom line, do whatever floats your boat and be happy with it. I don't need anybody to tell me what to enjoy, and I'm not to tell anybody what he should enjoy... .

This is and never was about telling anyone what to like or dislike

but it is a discussion on the merits for and or against a certain way of doing things

as stated in the thread title

This is my argument "pro" capacitor coupling

Not that i have anything against direct coupling

I am just not going to lose any sleep trying to figure out how to get the final capacitor out of the signal path without blowing up my power amp or mucking up the simplicity of the original circuit topology

guess i just mellowe with age

NOT !!!!!