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post #46 of 176
Quote:
True Class A AFAIK has to either dump heat in the voice coils of the speakers or it dumps it into the heat sink. So if it is designed to run in class A for 100w, the 100w must be dissipated somewhere continuously. That's the heat coming off a 100w light bulb!
not exactly.

The actual class-a device must dissapate the full output power it is capable of all the time.There is no "idel" current spec then"output current" spec because the idle current IS the output current !
This places a huge stress on the device being called on to provide this current so for a 10W class-a amp the heat sink area would be equal to a 200W class A/B amp because even though the A/B amp can produce 200 ultimate watts it does not do this all the time and in fact may do so for a fraction of a second once a week if layed all day and all night.The trasistors are idleing until called on and then only for one half of the audio signal so 50% of a % of the signal.

If your car was a class A amp it would be like putting it on a dyno and pegging the gas peddle to the floor and holding it there where AB would be your engine idling at a red light ready to go but not using any real power until you hitr the gas then the power in relation to how far you push the pedal
post #47 of 176
Thread Starter 
Quote:
Originally Posted by rickcr42
reality check time :

Point #1-the first "Op-Amps" were TUBE devices using 12AX7 tubes

Point #2-You folks need to get your heads out of the "tubes are colored" thought pattern and realise tube gear can be every bit if not more accurate as any solid state design known to man and if it is colored either by intent (to satisfy the ignorant) or by mistake because the designer has no clue.

Point #3-Every time i read "the opamp has a tube like quality" I crack up becuase it is more than obvious most have no idea what that means yet buy the device anyway because of the "con job" going on.

"sounds like tubes" has become a code word for "sounds great" yet the same person who would buy this "great sounding" piece of solid state gear (because most sounds like crap and will give you ear bleed) would in the next breath call tube gear colored as a way to slam it.
I stand by my statement with the following clarifications:

a) It seems that most people gravitate towards tubes because of their warmth and smoothness (which is also what I hear btw). Why bother otherwise? If that is a common trait of tube amps, that is their coloration. That doesn't automatically make it a negative thing. If paired with a super fast/flat DAC and revealing headphones its almost certainly a good thing. I don't think any amp is strictly neutral, the materials and technologies used in discrete SS amps vs tube amps each add their own specific colorations. Here's an interesting article on the subject that I enjoyed: http://www.allaboutcircuits.com/vol_3/chpt_13/12.html

b) I mostly referred to the opamp comparison as fiddling with tubes seems to be a common past-time, ala SS op-amps.

c) My original post intentionally omitted tube amps, as they an additional variable that unnecessarily complicates the issue of discrete SS vs op-amp.

All that said I have nothing against tube amps, in fact if someone has recommendations for the most neutral and balanced tube & amp combo I'd love to hear it (best for say HP-2 / HP3000). My only real complaint about tube amps is that they don't really seem to fit my plug & play style of life.

Thank you for all the great responses, this thread is very informational!
post #48 of 176
Quote:
Originally Posted by rickcr42
Granted but my personal listening says if the leading edge response is good and everything stops simultaneously the resulting sound is much more pleasing to listen to than class A/B crossover distortion.

Remeber what Timbre is and what most music systems do to that paricular parameter.

Systems A and Sytem B side by side,both equal in dollar value,both sound good,both playing the same identical CD with the same source and same final transducer and you have what ? Two entirely different sounding syustems even though they play the same song !

Which is true to the original "timbre" and which if either dead accurate ? My taste goes to getting the sound of my system to where it plays music.where i actually want to jump around like an idiot of dance or tap my feet to the beat not analyze the inner details of if the instrument is or is not dead on to what i remeber which would change in "timbre" from hall A to hall B anyway.

Class B can be very musical as can A/B but when compred to class a there is no contest for me

I guess ultimately it does come down to listening to pick the lesser evil between crossover distortion and losing a little bit of the leading edge of notes.

I suppose timbre can be a relative thing but the research showed that it was what allowed people to pick out violin playing say 1000Hz fundamental note vs. a 1000Hz sine wave. They showed that if they took out enough of the leading edge people found it difficult to distinguish sine waves from instruments. I don't know how much they had to had out to do that and how much a class B implementation might take out though (probably much much less).
post #49 of 176
Quote:
Originally Posted by rickcr42
not exactly.

The actual class-a device must dissapate the full output power it is capable of all the time.There is no "idel" current spec then"output current" spec because the idle current IS the output current !
This places a huge stress on the device being called on to provide this current so for a 10W class-a amp the heat sink area would be equal to a 200W class A/B amp because even though the A/B amp can produce 200 ultimate watts it does not do this all the time and in fact may do so for a fraction of a second once a week if layed all day and all night.The trasistors are idleing until called on and then only for one half of the audio signal so 50% of a % of the signal.

If your car was a class A amp it would be like putting it on a dyno and pegging the gas peddle to the floor and holding it there where AB would be your engine idling at a red light ready to go but not using any real power until you hitr the gas then the power in relation to how far you push the pedal
Right, maybe I wasn't clear in how I said it. So if have the volume on minimum the 100w must be dissipated by the heat sink if have it high enough that on average the speakers are getting 50w continuous average power then the device dissipates 50w and the speaker voice coils dissipate 50w.

So an amp designed for 100w class A must have heat sinks that can dissipate the heat of a 100w light bulb all the time for those moments when they are on but not playing any music.
post #50 of 176
Quote:
Not intended Rick, I just found your statement very puzzling. I don't understand the difference between partial biasing and full biasing of an opamp, but will look it up... thanks for enlightening me on that one.
Fair enough.I just felt you went a bit overboard with the adverbs

What you are confusing is a partial biasing of one set of the output transistors into class-A with a "full" class-A operation.

In simple terms :

say you have an opamp that can produce 50mA output current but it idles at only 5mA when no music is playing.That means you are using little power and generating very little heat while at idle but for peaks you are getting the ful output in momentary bursts.Since this is a short term event the device can handle it simply because no heat builds up.it is more LITTLE BIT ON...OFF....LITTLE BIT ON...LITTLE BIT LESS....FULL ON.....OFF

That is how music is translated at the output stage even if all the front end stages ARE clas-a.Since they are not called on to produce any real power even class-A here is a low current condition.

Full class-A is just ON all the time as long as the power switch is in the on position.
Full tilt all the time and that is not a condition any small plastic non heat sinked package can sustain beciase the trasistors will overheat and detonate and that withing a microsecond even without music present

What you are confusing with pure class-A is the partial class-A biasing of an opamp output stage.
This increases low level detail up to a higher point than would otherwise be possible because more of the signal is in the class a region
The ultimate total output power is not effected one bit and remains in B or AB on peaks but since most music is really low power demanding the majority of the song will be in the class a region with the peaks being the more efficient B or AB

Example :

You have the above example opamp capable of 50 mA peak current output that idels at 5ma.If you tie one of the output transistors to a power supply rail through a resistor (for example) you can set the class-A operation to maybe 10mA (RARE !) with the other 40 mA still remaining in the AB region for peak events.The danger here is go to far into class A and you burn up the output stage and why you normally see a low number here.It improves low level detail but go too far and you are replacing the device
post #51 of 176
Quote:
Originally Posted by wakked1
I stand by my statement with the following clarifications:

a) It seems that most people gravitate towards tubes because of their warmth and smoothness (which is also what I hear btw). Why bother otherwise? If that is a common trait of tube amps, that is their coloration. That doesn't automatically make it a negative thing. If paired with a super fast/flat DAC and revealing headphones its almost certainly a good thing. I don't think any amp is strictly neutral, the materials and technologies used in discrete SS amps vs tube amps each add their own specific colorations. Here's an interesting article on the subject that I enjoyed: http://www.allaboutcircuits.com/vol_3/chpt_13/12.html

b) I mostly referred to the opamp comparison as fiddling with tubes seems to be a common past-time, ala SS op-amps.

c) My original post intentionally omitted tube amps, as they an additional variable that unnecessarily complicates the issue of discrete SS vs op-amp.

All that said I have nothing against tube amps, in fact if someone has recommendations for the most neutral and balanced tube & amp combo I'd love to hear it (best for say HP-2 / HP3000). My only real complaint about tube amps is that they don't really seem to fit my plug & play style of life.

Thank you for all the great responses, this thread is very informational!
The article you linked to is good but it should be read carefully. The effect of microphonics in headphone setup is non-existant. The article states the author's belief that microphonics is the reason behind the euphony associated with tube amps.

He also mentions how tubes have superior high temperature characteristics that lend them to be used in class A configurations and how a solid state devices change in character as they reach the higher temperature necessary in class A operation.
post #52 of 176
I've spent hundreds of hours pouring through reams of posts here since late November. The system I have now is a "passifier" until I can come to some kind of cognitive rest over the next chosen upgrade that I'll take. The problem is, if you keep reading here, you keep running into more and more issues that need to be researched and resolved and that cognitive rest seems to be further and further away. While it's fun, it can be somewhat disconcerting. Fortunately, I have time for the due diligence. It would be nice to be able to listen to all the different combinations, though, which is difficult unless one attends a meet.

I certainly don't have a problem with someone telling me, publicly or through PM, that I could have done better with my money. That's what I'm here for! To learn from everyone who has experience and access to the equipment. I like the equipment I have now, but I want my next upgrade step to be as informed as possible. Having access to threads like this really helps, even though it's above my head for now. It'll force me to do some more research.

If I was forced to make a decision today with everything I've learned here at Head-Fi I would probably end up using a Lavry DA10 --> Singlepower MPX3. I'm not sure if I want to go back to using a redbook player, such as the Rega Apollo, or continue with computer audio. I just haven't made up my mind about that yet. I'm also keeping the Headroom balanced amps in mind, but they are expensive.

EDIT: Holy cow, active thread! This reply mainly goes back to some things Rick replied to - but anyone can chime in!
post #53 of 176
Quote:
a) It seems that most people gravitate towards tubes because of their warmth and smoothness (which is also what I hear btw). Why bother otherwise?
how about harmonic accuracy and a retention of the "space" that no solid state gear i have ever heard can match ? Solid state can sound great but still has a way of taking a three dimensional image and make it two dimensional.warm ? Maybe my ratty old Dyna PAS 2 can be called warm but that is not how any of my tube gear can be described at all.not even close

Quote:
If paired with a super fast/flat DAC and revealing headphones its almost certainly a good thing
if it was only super fast and revealing you would have no need to "tame" it so instead what you are describing is a hard sounding comprimised design needing help to sound good.My DACs are DIY and have no real output stage other than passive so what comes out is "as it is" literal and needing no "help" does fine with any good line stage be it solid state or triode.

Quote:
I don't think any amp is strictly neutral, the materials and technologies used in discrete SS amps vs tube amps each add their own specific colorations. Here's an interesting article on the subject that I enjoyed
there is no nuetral.If it is in the signal path it is adding some of its own character to the sound.he trick is to limit the butchering not hide faults.If you have sonic problems look to the front end and work your way forward to the speakers/headphones.Garbage in/garbage out

Quote:
b) I mostly referred to the opamp comparison as fiddling with tubes seems to be a common past-time, ala SS op-amps.
already addressed.Discrete opamp whips monolithic opamp for the reason stated

Quote:
c) My original post intentionally omitted tube amps, as they an additional variable that unnecessarily complicates the issue of discrete SS vs op-amp.
the discussion had already strayed and was full of misconceptions so i took it as my personal responsibility to set the record straight from my experience and vantage point.I am multi-topology-lingual

Quote:
All that said I have nothing against tube amps, in fact if someone has recommendations for the most neutral and balanced tube & amp combo I'd love to hear it (best for say HP-2 / HP3000). My only real complaint about tube amps is that they don't really seem to fit my plug & play style of life.
that is where I usually take a pass.Product specific is way more than the "what amp sound BEST" and way into system matchups so better to ask "what amps should be on my list for review with my system and my musical taste.I listen loud (or soft !) and like to pump in the bass (or not) and need to.........."
There is no one true answer only what suits you at the time.Most good products are well known so it comes down to read the review,gather information,make a list then go listen with YOUR CDs and hopefully a sytem close to your own.Really the only way.

Quote:
Thank you for all the great responses, this thread is very informational!
Hopefully.A lot of misinformation is let go and when it is taken for fact so every once in a while I jump in and piss everyone off
post #54 of 176
Quote:
Right, maybe I wasn't clear in how I said it. So if have the volume on minimum the 100w must be dissipated by the heat sink if have it high enough that on average the speakers are getting 50w continuous average power then the device dissipates 50w and the speaker voice coils dissipate 50w. Is that true?
with pure class-a you are at full 100% dissapation as long as the power switch is on.with class A/B you are at whatever the bias point is as a % of the max power so will run cool at idle putting less emphasis on the cooling.even with a music event you will likely be at 25-30% of full power even at loud levels with the rest there for the extremely loud peak.anything over that will be either signal compression or a clipped signal.

Speakers dissapate power the same way an amp does but for entirely different reasons.Even though a class a amp is burning the fires the speaker is OFF until there is an actual signal.What kills home speakers (and why pro speakers have huge metal voice cols and heat sinking for them) is the long term (over time) loud music.Loud peaks are cast of as nothing,loud music over three hours will burn a voice coil if the speaker is not up to it.

Quote:
So an amp designed for 100w class A must have heat sinks that can dissipate the heat of a 100w light bulb all the time for those moments when they are on but not playing any music.
No.More like a 1,000 watt light bulb ! We are talking sious heat here.enough to make you not want to stand close to the amp during the warmer months and enough to qualify as back up heat in the winter.

you are still confusing the steady state power dissapation of class A with the idle/on/peak dissapation of class AB.The heat sink only need handle the full 100 watts for a very short amont of time (milliseconds) but the class A ALL the time from the moment you turn on the power switch even if no music is playing
post #55 of 176
Rickcr42,

Here's an article that talks briefly about how both class B and class AB present with crossover distortion but that class-AB is likely to show it in a more critical part of the waveform.

http://www.tcaas.btinternet.co.uk/jlhab2.htm
post #56 of 176
Quote:
If I was forced to make a decision today with everything I've learned here at Head-Fi I would probably end up using a Lavry DA10 --> Singlepower MPX3. I'm not sure if I want to go back to using a redbook player, such as the Rega Apollo, or continue with computer audio. I just haven't made up my mind about that yet. I'm also keeping the Headroom balanced amps in mind, but they are expensive
why limit formats ?

My personal beleif is there is a place for everything and to get the best from each you need to focus on that,take it to a level you are content with then move to the next "thing" in line.
CD is still best done with a "redbook" Cd player so asuming you have an extensive collection you should have the best player you can afford for CD playback.The multiformat player will work but if you want the best ultimate sound stick to a Cd player for a CD then buy a DVD-A/SACD player for that format.
Computer audio is another beast that you may need to focus on even though your results so far not as expected when compared to CD/SACD.Total home AV hardware integration is coming and better to sqeeze all you can from it than to avoid it because while it may not be THE format it will be A format.

I have so far :

1-Cassette
2-open Reel
3-VCR as audio recorder
4-Vinyl rig ready for 45,33 1/3,78
5-Minidisc recorder
6-USB from computer to DAC to system for ANY format the computer itself can handle
7-CD Player
8-DVD Player
9-CD and DVD recorder at the coputer
10-SACD or DVD-A when they get theri sh*t together and i don't go through the "VHS or Betamax" crap again

I use all formats and enjoy each.no favorites just another way to play or record music
post #57 of 176
Quote:
Here's an article that talks briefly about how both class B and class AB present with crossover distortion but that class-AB is likely to show it in a more critical part of the waveform.
Pretty much agrees with everything I said.I guess I am in good comapny for a hack
post #58 of 176
Quote:
Originally Posted by rickcr42
with pure class-a you are at full 100% dissapation as long as the power switch is on.with class A/B you are at whatever the bias point is as a % of the max power so will run cool at idle putting less emphasis on the cooling.even with a music event you will likely be at 25-30% of full power even at loud levels with the rest there for the extremely loud peak.anything over that will be either signal compression or a clipped signal.

Speakers dissapate power the same way an amp does but for entirely different reasons.Even though a class a amp is burning the fires the speaker is OFF until there is an actual signal.What kills home speakers (and why pro speakers have huge metal voice cols and heat sinking for them) is the long term (over time) loud music.Loud peaks are cast of as nothing,loud music over three hours will burn a voice coil if the speaker is not up to it.



No.More like a 1,000 watt light bulb ! We are talking sious heat here.enough to make you not want to stand close to the amp during the warmer months and enough to qualify as back up heat in the winter.

you are still confusing the steady state power dissapation of class A with the idle/on/peak dissapation of class AB.The heat sink only need handle the full 100 watts for a very short amont of time (milliseconds) but the class A ALL the time from the moment you turn on the power switch even if no music is playing
So you're saying that if a 100w rated class A amp is playing a 1000Hz tone at 100w RMS into a resistor the heat sink must still dissipate 100w? I think in that situation the power transistors won't have to dissipate that heat but instead that poor resistor will have to.

If this is true then that 100w gets converted to heat either at the transistors or in speakers. If not then does that mean that both the transistors and the resistor/speakers will have to dissipate 100w each?
post #59 of 176
You need to not think power and think heat.I have a 10 watt class a amp with HUGE heat sinks that you could not put your hand on for more than a minute.
I have a 1 Watt class A amp that uses a heat sink meant for a 'normal" 25 watt amp and it is HOT to the touch.

Extrapolate that down to opamp power levels and what the requirements would be for a heat sink if the device was run full class a and even at 10mW you are looking at a quater size heat sink or the tansistors would burn up in minutes if not seconds


Obviously the above is output stage power and not the front end which sees an entirely different load.

how do you get the best out of opamps and discrete ? Partial Class-A biased opamp to a true class a output stage.not as good as all discrete but better than the naked opamp could ever hope to be alone driving a headphone load This is why my favorite buffer is still the TO package LH0066 and its little brother the ceramic DIP package LH0033.Both using a bipolar transistor output (0066 is doubled up) A operation with an FET front end.
The LH0066 puts out around 2 watts and is a straight buffer (no gain) yet each one of the stero pair sits on a custom 5x6x1.5 heat sink !!!
post #60 of 176
Thread Starter 
Quote:
Originally Posted by sxr71
The article you linked to is good but it should be read carefully. The effect of microphonics in headphone setup is non-existant. The article states the author's belief that microphonics is the reason behind the euphony associated with tube amps.

He also mentions how tubes have superior high temperature characteristics that lend them to be used in class A configurations and how a solid state devices change in character as they reach the higher temperature necessary in class A operation.
Just a note regarding temperatures... amp like engines should be built to operate optimally at their fully warmed up & loaded state. I thought it was just my imagination but even the GL sounds significantly better after at least a few hours of warmup.
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