Class A vs. Class AB 'loudness'...

the orangewizard · Post by **the orangewizard** » Fri Jul 21, 2006 5:41 am

First off,I'll begin by saying that for this post,I d'ont require yet another detailed explanation of how the 2 classes operate(I've read enough of them to know that I do not even remotely understand it!

)That said,I spoke with a sales rep of one of the major online gear stores today,and he said that class A watts are 'louder' than class AB ones.To be more specific,he stated that a 30 watt 'class A' head should put out a volume,or "apparent loudness" equivalent to that of a 60 watt 'class AB' head.Any thoughts,or experiences on this? I'm learning more about this whole tube amp thing every day,but still consider myself to be pretty ignorant-so any helpful info on this would be much appreciated!

irish_admiral · Post by **irish_admiral** » Fri Jul 21, 2006 12:27 pm

He's talking crap.

It depends which harmonics the amp emphasises. Valve amps tend to sound louder than equivalent wattage SS amps as they put out more even order harmonics.

a.hun · Post by **a.hun** » Fri Jul 21, 2006 7:26 pm

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by irish_admiral
 He's talking crap.<hr height="1" noshade id="quote"></blockquote id="quote">He is, but only partly...

CATHODE biased amps have a much stronger 'attack' then fixed bias ones. Nothing to do with the operating class though...
http://www.thegearpage.net/board/showth ... ght=attack
And the last post here:
http://www.thegearpage.net/board/showth ... ght=attack
Andy.
(Yes, that one...

)

irish_admiral · Post by **irish_admiral** » Fri Jul 21, 2006 10:50 pm

Hi Andy, welcome to the forum?

What do you mean by attack? For example, i'd say my AD30 (cathode biased) seems to have a softer feel & attack than other non-cathode biased amps...

a.hun · Post by **a.hun** » Sat Jul 22, 2006 1:35 pm

Hi Joe. Thanks for the welcome.

Yeah, I'm just logging in with my original username from way back when while on hols in Scotland, before heading back to Amstermad in a couple of days. (Actually had a small handful of posts ages ago in this name which were lost when there was that forum failure not so long back). Anyway, Andy H. will return... [:p]

You may well be right about the AD30. More then one design factor at play of course, and the intention was never to make something too edgy with that amp.

What I'm meaning by attack is the amps initial response to a hard picked note or chord. The very start of the note or waveform. Powerful attack gives a real punch to the sound and can make an amp seem apparently louder then its wattage rating would suggest. There is a strong psycho acoustic effect as the ear is much more sensitive to sudden loud noises then to continuous loudness, so the initial attack plays a big part in the percieved loudness of any musical note.

Several of the low wattage Mesa Boogies (like my own Subway) use a system called 'Dyna Watt' which basically stores up some energy in big capacitors to release over the first fraction of a second when there is a high power demand. It is then stored up again as soon as possible. Mine is only a 20 odd watt amp but it is seriously loud and punchy as a result. And it isn't cathode biased...

Andy.

irish_admiral · Post by **irish_admiral** » Sat Jul 22, 2006 3:14 pm

Thought you may have been masquerading as a Hungarian... hence the ?

Sounds like a clever gizmo in the Mesas...

Andy H. · Post by **Andy H.** » Tue Jul 25, 2006 2:04 pm

I don't need to masquerade - I have 50% genuine Magyar blood in my veins and 50% Scots.
(All the rest is probably beer and whisky...

)

Randall Smith (Mr. Boogie) is a clever chappie. Here is the Dyna Watt patent if you're interested... [:p]

http://patft.uspto.gov/netacgi/nph-Pars ... PN/4713624

Andy.

irish_admiral · Post by **irish_admiral** » Tue Jul 25, 2006 4:34 pm

50% Magyar blood in your alcohol-stream...

Andy H. · Post by **Andy H.** » Tue Jul 25, 2006 6:16 pm

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by irish_admiral
 50% Magyar blood in your alcohol-stream...
<hr height="1" noshade id="quote"></blockquote id="quote">Thats another way of putting it I guess...

:?[:p]

Andy.

bgarrett_uk · Post by **bgarrett_uk** » Tue Jul 25, 2006 7:43 pm

50% Magyar + 50% Scots + ?% Alcohol = is greater than the sum of the parts. Yes?

If it takes one man a week to walk a fortnight.
How long does it take two men to walk three weeks?

Answers on a postcard please to Mr Andy Heatlie.... thanks.

Andy H. · Post by **Andy H.** » Tue Jul 25, 2006 10:25 pm

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by bgarrett_uk
 50% Magyar + 50% Scots + ?% Alcohol = is greater than the sum of the parts. Yes? <hr height="1" noshade id="quote"></blockquote id="quote"> Oh definitely! <blockquote id="quote">quote:<hr height="1" noshade id="quote">

If it takes one man a week to walk a fortnight.
How long does it take two men to walk three weeks?<hr height="1" noshade id="quote"></blockquote id="quote"> What have they been drinking, and did they have enough for the bill? <blockquote id="quote">quote:<hr height="1" noshade id="quote">

Answers on a postcard please to Mr Andy Heatlie.... thanks.<hr height="1" noshade id="quote"></blockquote id="quote"> Wassa question 'gain, professor?
(Hic...!

)

<s>Adny</s>
<s>Ydna</s>
Attila the Hun.

(c/o the very nice brewery by the big windmill, Amstermad, Hollandland. Though they sometimes let me out for good behaviour...

:D:D)

Class A vs. Class AB 'loudness'...

Who is online