Class A

DocfosterDocfoster
edited May 2014 in Amplifiers
Haven't started a thread for a while, and feeling guilty...

I've been loving that Class A sound lately. And had an exchange with an old friend today (certainly not an audioforum type person) about that Class A thang.
Just wanted to get responses to any of these general comments he came up with...

"They avoid crossover distortion at the expense of lower efficiency...But of course it all depends on the implementation.
You can make a crappy class A or a really good class B. And class B
probably tends to be more symmetrical, leading to odd rather than even
harmonics. Class A possibly gives more of an even harmonic tubey sound...I might want to check that odd harmonic stuff. It might be pub induced bollocks."

Col's stuff is, of course well implremented. :-) I'll put that out there straight away.
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Comments

  • uglymusicuglymusic
    "They avoid crossover distortion at the expense of crossover distortion 
    Did he really say that?
  • DocfosterDocfoster
    "They avoid crossover distortion at the expense of crossover distortion 
    Did he really say that?
    No Dave. No he did not. D'oh!
    Duly corrected. Thanks... :-)
  • ColinColin
    Maybe Ben you should list all the types of amplifiers and give us a brief explanation, and uses.
    And why some designs perform better with valve (tube) designs than semiconductors.
    And the sub-categories of classes within the class type could be interesting reading.
  • AlanAlan
    I know very little about this stuff, and what I think I know is mostly what has been explained to me, so I don't actually know anything....

    However, crossover distortion cannot be what class A 'magic' is all about. I have SECA amps and class A/B amps, the class A/B I'm using at the moment has sliding bias that is specifically designed to deal with crossover distortion. The amp also runs much of the time in class A (though I would guess push-pull, rather than single ended).

    The main point here, based on nothing but my own experience, is that these different amps sound utterly different, and neither has problems with crossover distortion. So it can't be a critical differentiating factor in well designed amplifiers.


  • DocfosterDocfoster
    I can only guess at what crossover distortion is...

    Col', for Ben's A-Z alphabet amplifier guide i'll do my best. Here goes, I'll do it reverse order...

    Class Z amps: These are stripey and designed to work well on the savannah. They do not perform well with the US hard rock band 'Lions'.
  • uglymusicuglymusic
    Can you eliminate crossover distortion in a non-single-ended design?
  • ColinColin
    I can only guess at what crossover distortion is...

    Col', for Ben's A-Z alphabet amplifier guide i'll do my best. Here goes, I'll do it reverse order...

    Class Z amps: These are stripey and designed to work well on the savannah. They do not perform well with the US hard rock band 'Lions'.
    Oh "Wim Away"
  • ColinColin
    Can you eliminate crossover distortion in a non-single-ended design?
    Maybe you tell us Dave
  • uglymusicuglymusic
    Hang on, should we be talking switching distortion here?

    I think I should be Googling rather than using that grey mushy stuff.
  • ColinColin
    Mushy stuff is good, and tasty mmm

  • uglymusicuglymusic
    Some people like that green mushy stuff, but only marsh creatures from the east feast on grey mushy stuff. I'm told.
  • ColinColin
    Yep from Epping and beyond.
  • ColinColin
    edited May 2014
    This site has some very interesting article including Class of amplifiers and speaker crossover, well worth a look.





  • DocfosterDocfoster
    Thanks Col...!
  • ColinColin
    Thanks Col...!
    Welcome, some good stuff on that site, some a little off but hey ho so what.
  • ColinColin
    image
  • uglymusicuglymusic
    Gimme!
  • ColinColin
    Gimme!
    You just like the Red button.

  • DocfosterDocfoster
    What are the dimensions and weight on that Col?
  • ColinColin
    Weight: 21kg
    dimensions:
    (WxHxD) 
    430x290x220mm
  • AlanAlan
    Bootiful.

    I wonder how big & heavy a pair of 100W monos would be?

    Makes my MDF & bathroom tile chassis look a bit naff tbh...
  • ColinColin
    edited May 2014
    Bootiful.

    I wonder how big & heavy a pair of 100W monos would be?

    Makes my MDF & bathroom tile chassis look a bit naff tbh...
    Weight: 58kg
    dimensions:
    (WxHxD) 
    430x380x380mm
    EACH TINY ONES
  • AlanAlan
    Now that's doing it properly!

    Could I trade in some children to work in the TQ sweatshop in part ex? Mind you, they don't weigh 58kg each...
  • quickiequickie
    edited May 2014
    imageimageimage
    A featherweight at only 11 kg :)



    imageimage
  • DocfosterDocfoster
    ...but isn't that only half a one...?
  • quickiequickie
    It will be one of two (when i've built it) :)
  • ColinColin
    edited May 2014
    It will be one of two (when i've built it) :)
    Well get on with it Alan built his in 2 days, you have had 20yrs, slacker.  :)) >:) :D

    And no lids? but they do look good Paul, I come and hear them soon. PM read
  • DocfosterDocfoster
    It will be one of two (when i've built it) :)
    So 22kg in total - just ahead of Col's...
    ;-)
  • ColinColin
    It will be one of two (when i've built it) :)
    So 22kg in total - just ahead of Col's...
    ;-)
    Yes but he has more nuts in his, Colnuts and Quicnuts.
  • quickiequickie
    .....more like coconuts !
  • AlanAlan
    Paul - that really looks lovely. Lovely workmanship.

    The case design is a very elegant approach, it reminds me of the smaller burning amp chassis.
  • ColinColin
    .....more like coconuts !

    :-)) yep, I got the A Class SECA pre working, sounds good, ugly but sounds good.
  • AlanAlan
    My one has a pair of ring donuts, but they're pretty small.
  • ColinColin
    edited May 2014
    My one has a pair of ring donuts, but they're pretty small.
    Stop boasting  for a 27W SECA I thing 300VA should be big enough.
    Paul's are biased at a slightly higher current and will need a bigger Jam donuts Policeman on stake out size.
    ~O)
  • AlanAlan
    I did upgrade them to 'audiophile stakeout level 5' by putting sprinkles on them...

    I didn't know they were 300va traffos? I guess that last moment transformer change threw me.
  • ColinColin
    I did upgrade them to 'audiophile stakeout level 5' by putting sprinkles on them...

    I didn't know they were 300va traffos? I guess that last moment transformer change threw me.
    God they must be heavy to throw a huge man like you. >:)
  • quickiequickie
    .....more like coconuts !

    :-)) yep, I got the A Class SECA pre working, sounds good, ugly but sounds good.
    Yipee.....:)
  • quickiequickie
    Paul - that really looks lovely. Lovely workmanship.

    The case design is a very elegant approach, it reminds me of the smaller burning amp chassis.
    Thanks Alan. Probably 90% of the work is drilling and tapping bloody holes !

    I might get them anodised purple (or paint)
  • uglymusicuglymusic
    Gimme!
    You just like the Red button.

    Honestly, why else would anyone want one of those?
  • uglymusicuglymusic
    edited May 2014

    A featherweight at only 11 kg :)



    imageimage
    Wow! That's looking good, Paul.

    I just said something mildly rude to Col over at AoS because I hadn't seen these. Happy to delete if you feel I was rude against you (as I said Col was the target, not you).

    Please ignore the above para, Paul. I've censored myself. Feeling a bit pissed following our neighbour's BBQ.
  • uglymusicuglymusic
    Paul - that really looks lovely. Lovely workmanship.

    The case design is a very elegant approach, it reminds me of the smaller burning amp chassis.
    Thanks Alan. Probably 90% of the work is drilling and tapping bloody holes !

    I might get them anodised purple (or paint)
    Not you as well. Colin keeps wanting to anodise my TDSs.
  • ColinColin

    A featherweight at only 11 kg :)



    imageimage
    Wow! That's looking good, Paul.

    I just said something mildly rude to Col over at AoS because I hadn't seen these. Happy to delete if you feel I was rude against you (as I said Col was the target, not you).

    Please ignore the above para, Paul. I've censored myself. Feeling a bit pissed following our neighbour's BBQ.
    Rude, were bunny no way they stay here.
  • quickiequickie
    No worries Dave !

    Black would do me, but shmbo thinks otherwise.........
  • ColinColin
    No worries Dave !

    Black would do me, but shmbo thinks otherwise.........
    Zirconium Blue is lovely changes as you move, and there is thermal paint that changes colour as they get hot.
  • chrisbchrisb
    come to the paint man anything you like.
  • quickiequickie
    Pink with black spots.........
  • chrisbchrisb
    Anything !
  • jandl100jandl100
    I'd love to hear the TQ class A beasties. But I have to say that I've heard a whole bunch of tranny class A amps and those were all, without exception, a bit laid back and well, boring, to my humble ears. Their get up & go had kind of gotten up & gone. I-) I've heard tell that the TQ amps are different. Could be.

    Class A valve amps don't seem to suffer from this.
  • uglymusicuglymusic
    The Green Goddess is gentle when she needs to be, but I recently made a visitor sit up when I blasted a Metallica HD file at him. He had been lulled into a false sense of what the amp is about :-)

    Also take note of my musical taste: boring gear doesn't get a look in!
  • AlanAlan
    SECAs do the soft emotional bit superlatively well though, IMO. They seem equally at home on either end of the spectrum.
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