AlurkA Posted May 5, 2019 Share Posted May 5, 2019 Is it even possible to do a comparison, or are they completely different beasts designed for disparet system configurations? I have speakers that are difficult to drive and am currently running an Accuphase integrated rated at 260W/Channel into 4Ohm. Toying with idea of trying out a Class A Amp and am wondering whether a Class A amps rated at 80W/Channel into 4Ohm is going to be able to drive my speakers. I have Dyn s5.4 rated at 87db. My listening levels are not extreme, but hey everyone likes to turn it up every now and then! I know its all subjective but would it be a backwards step, side step, am I likely to see an improvement in sound. Any advice or experience appreciated. Cheers Link to comment Share on other sites More sharing options...
Gryffles Posted May 5, 2019 Share Posted May 5, 2019 Please forget about comparing the two in regards to power ratings 80w is 80w no matter what class it is. See if you can borrow a Class A amp to try. I have had SS Class A amps and one I loved and the other not much at all and these were from the same manufacturer. Funnily enough it was the cheaper one I preferred. 4 Link to comment Share on other sites More sharing options...
davewantsmoore Posted May 5, 2019 Share Posted May 5, 2019 48 minutes ago, AlurkA said: Is it even possible to do a comparison, or are they completely different beasts designed for disparet system configurations? No, just 1:1. 10w is 10w. 1 Link to comment Share on other sites More sharing options...
Tony B Posted May 5, 2019 Share Posted May 5, 2019 Your speaker play well with class A amps. I've had great success with Plinius Class A and the 5.4's. 2 Link to comment Share on other sites More sharing options...
AlurkA Posted May 5, 2019 Author Share Posted May 5, 2019 Thanks Tony. Link to comment Share on other sites More sharing options...
AlurkA Posted May 5, 2019 Author Share Posted May 5, 2019 So my understanding of how all this works, and it is limited, is that an amp with more power (watts) has the ability to drive the same speaker to far greater volumes when listened to from the same distance. Given this a Class A amp will not have the ability to drive the said speaker to the same volume level as a higher wattage A/B. It would also have a reduced ability to cope with peak power demands when the music requires it. Provided the Class A amp can drive the speakers to the volume level required in the room and cope with peak demands the music places on it, in theory I take it the Class A amp would perform just as well as a Class A/B? Given this if power is taken out of the picture what does a Class A amp offer in comparison to A/B? Does it just come down to personal preference and the listening experience or is there some technical or architectural aspect of them that makes them a "better" amplifier? Link to comment Share on other sites More sharing options...
Cafad Posted May 5, 2019 Share Posted May 5, 2019 Because of the inefficiencies of the class A design all class A amps should have larger power supply sections than similarly rated class A/B amps. In some cases this can help them to sound more effortless than an A/B design. In answer to your question though yes, I do believe it is all down to personal taste. I tend to prefer the sound of class A/B amps. 2 Link to comment Share on other sites More sharing options...
Guest Muon N' Posted May 5, 2019 Share Posted May 5, 2019 (edited) Driving difficult speakers is about supplying plenty of current. If an amp say is rated at 140w into 8 ohms, and can deliver 250w to 270w into 4 ohms it is capable of supplying plenty of current and will cotrol very difficult speakers better than the following scenario......... If an amp is rated at 140w into 8 ohms and can deliver only 170w into 4 ohms It's pretty piss poor in the current capacity it can supply, in comparision. Edit: as I understand it, and you have to understand how difficult a given speaker load is, for this you need to look at the full frequency impedance plots and see how low it drops at different frequencies. Edited May 5, 2019 by Muon N' Link to comment Share on other sites More sharing options...
andyr Posted May 5, 2019 Share Posted May 5, 2019 3 hours ago, Cafad said: Because of the inefficiencies of the class A design all class A amps should have larger power supply sections than similarly rated class A/B amps. In some cases this can help them to sound more effortless than an A/B design. ^^^ What he said! The larger PS in the Class A can often deliver more current than an AB amp of greater power. I'm thinking PASS amps which, say, are only 50wpc into 8 ohms - but are known to drive Maggies well. (Maggies like current. ) 3 hours ago, Cafad said: In answer to your question though yes, I do believe it is all down to personal taste. I tend to prefer the sound of class A/B amps. The only Class A amp I've heard was amazing! However, I hope to hear another one later this year ... as Hugh Dean is coming out with a 35w Class A amp. Andy Link to comment Share on other sites More sharing options...
Volunteer sir sanders zingmore Posted May 5, 2019 Volunteer Share Posted May 5, 2019 My understanding of Class A amps is that their power is constant even when the load varies. So a class A amp that is 35w into 8 ohms will also be 35w into 4 ohms. Link to comment Share on other sites More sharing options...
Addicted to music Posted May 5, 2019 Share Posted May 5, 2019 Class A has its output transistors bias constantly on. That’s why the they need a huge reserve in electrolytic filter caps. They are only around 25% efficient if not less. To make the most out of class A (max efficiency) you need to turned that volume pot to loud volume, when it’s not playing music and it’s sitting idle on, its literally a heater. 1 Link to comment Share on other sites More sharing options...
Cafad Posted May 5, 2019 Share Posted May 5, 2019 1 hour ago, Sir Sanders Zingmore said: My understanding of Class A amps is that their power is constant even when the load varies. So a class A amp that is 35w into 8 ohms will also be 35w into 4 ohms. The power draw from the wall is the wattage that doesn't vary, the output to the speaker will vary as per usual. 1 Link to comment Share on other sites More sharing options...
andyr Posted May 5, 2019 Share Posted May 5, 2019 1 hour ago, Sir Sanders Zingmore said: My understanding of Class A amps is that their power is constant even when the load varies. So a class A amp that is 35w into 8 ohms will also be 35w into 4 ohms. Trevor, you may very well be correct (I have nooo idea). However: A 35w Class A amp isn't limited to just outputting 35w. It moves into Class AB beyond this. The specs for (at least some of) Nelson Pass's Class A amps say they double in power as they go from 8 to 4 to 2 to 1 ohms. Andy Link to comment Share on other sites More sharing options...
Volunteer sir sanders zingmore Posted May 5, 2019 Volunteer Share Posted May 5, 2019 2 minutes ago, andyr said: Trevor, you may very well be correct (I have nooo idea). However: A 35w Class A amp isn't limited to just outputting 35w. It moves into Class AB beyond this. The specs for (at least some of) Nelson Pass's Class A amps say they double in power as they go from 8 to 4 to 2 to 1 ohms. Andy I found something like the quote from @Zaphod Beeblebrox that I was thinking of: On 04/03/2017 at 3:21 PM, Zaphod Beeblebrox said: Oh dear, can 'o worms time. Here's the dirty little secret about Class A amps: A Class A amp rated at 20 Watts @ 8 Ohms, will deliver: 10 Watts Class A @ 4 Ohms 5 Watts Class A @ 2 Ohms 2.5 Watts Class A @ 1 Ohm Link to comment Share on other sites More sharing options...
Gryffles Posted May 5, 2019 Share Posted May 5, 2019 17 minutes ago, andyr said: Trevor, you may very well be correct (I have nooo idea). However: A 35w Class A amp isn't limited to just outputting 35w. It moves into Class AB beyond this. The specs for (at least some of) Nelson Pass's Class A amps say they double in power as they go from 8 to 4 to 2 to 1 ohms. Andy Get what you mean Andy but an amp wouldn’t be Class A if it did either of the things in the two points you mention. Link to comment Share on other sites More sharing options...
andyr Posted May 5, 2019 Share Posted May 5, 2019 11 minutes ago, Sir Sanders Zingmore said: I found something like the quote from @Zaphod Beeblebrox that I was thinking of: Very interesting, Trevor. I have no idea ... however, the two - seemingly opposite ideas ("a Class A amp delivers half the power as the spkr impedance halves" (ZB) and "NP's Class A amps double down to 1 ohm") - may be brought into line by the fact that a, say, 35w Class A amp does't have a hard upper limit of 35w ... it simply moves into Class AB, beyond this? Andy Link to comment Share on other sites More sharing options...
andyr Posted May 5, 2019 Share Posted May 5, 2019 2 minutes ago, Gryffles said: Get what you mean Andy but an amp wouldn’t be Class A if it did either of the things in the two points you mention. You're welcome to argue with NP, G ... I realise I am not competent to do so! Andy Link to comment Share on other sites More sharing options...
Gryffles Posted May 5, 2019 Share Posted May 5, 2019 1 minute ago, andyr said: You're welcome to argue with NP, G ... I realise I am not competent to do so! Andy Lol, not arguing with anyone. Just my understanding. Link to comment Share on other sites More sharing options...
aussievintage Posted May 5, 2019 Share Posted May 5, 2019 31 minutes ago, andyr said: a, say, 35w Class A amp does't have a hard upper limit of 35w ... it simply moves into Class AB, beyond this? Maybe not It might just clip, if the biasing of the output device is half the power supply (pure class A). You are thinking of amps that claim class A up to a certain wattage, then AB after that, but they aren't pure class A. 1 Link to comment Share on other sites More sharing options...
joz Posted May 5, 2019 Share Posted May 5, 2019 3 hours ago, Sir Sanders Zingmore said: My understanding of Class A amps is that their power is constant even when the load varies. So a class A amp that is 35w into 8 ohms will also be 35w into 4 ohms. So does that mean it’s less dynamic? Link to comment Share on other sites More sharing options...
betty boop Posted May 5, 2019 Share Posted May 5, 2019 10 hours ago, AlurkA said: Is it even possible to do a comparison, or are they completely different beasts designed for disparet system configurations? I have speakers that are difficult to drive and am currently running an Accuphase integrated rated at 260W/Channel into 4Ohm. Toying with idea of trying out a Class A Amp and am wondering whether a Class A amps rated at 80W/Channel into 4Ohm is going to be able to drive my speakers. I have Dyn s5.4 rated at 87db. My listening levels are not extreme, but hey everyone likes to turn it up every now and then! I know its all subjective but would it be a backwards step, side step, am I likely to see an improvement in sound. Any advice or experience appreciated. Cheers very unfortunately makers dont exactly use same methods to spec power outputs. we tend to have from the down right conservative leading to under quoting to those that are more something to do with marketing than anything akin to reality as a heads up in my bedroom setup with a couple of stand mounts (89db efficiency dropping to 4 ohm) I've had big behemoth integrated rated at 150wpc weighing in at 30kg, to 250wpc AB dual mono class AB power amp.. and yet best sounding so far is a class A valve integrated rated at some 35wpc... it weighs in at 25 kg ! watts aint watts .... and to improvements or not... best ot listen to speakers themselves with amps in question to decide 3 Link to comment Share on other sites More sharing options...
Addicted to music Posted May 5, 2019 Share Posted May 5, 2019 7 hours ago, betty boop said: very unfortunately makers dont exactly use same methods to spec power outputs. we tend to have from the down right conservative leading to under quoting to those that are more something to do with marketing than anything akin to reality as a heads up in my bedroom setup with a couple of stand mounts (89db efficiency dropping to 4 ohm) I've had big behemoth integrated rated at 150wpc weighing in at 30kg, to 250wpc AB dual mono class AB power amp.. and yet best sounding so far is a class A valve integrated rated at some 35wpc... it weighs in at 25 kg ! watts aint watts .... and to improvements or not... best ot listen to speakers themselves with amps in question to decide Enjoyable presentation to watch...... but you need to see the entire video 1 Link to comment Share on other sites More sharing options...
aussievintage Posted May 5, 2019 Share Posted May 5, 2019 8 hours ago, joz said: So does that mean it’s less dynamic? No. Measurement of power is just that. As for being "dynamic", that probably depends more on the quality/size of the power supply, and I don't agree that a class A amp always puts out the same power regardless of the speaker impedance for the same reason. Link to comment Share on other sites More sharing options...
Wimbo Posted May 5, 2019 Share Posted May 5, 2019 Mark Levinson ML2. 20 Watts Class A. These never have a RMS rating. Link to comment Share on other sites More sharing options...
aussievintage Posted May 5, 2019 Share Posted May 5, 2019 2 minutes ago, Wimbo said: These never have a RMS rating. The use of RMS when quoting watts can start a whole other debate 1 Link to comment Share on other sites More sharing options...
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