In the past I was critical about the benefits of Class A in poweramplifiers mainly due to the vast resources of material (big powersupply, heatsinks..) and environmental footprint.
I saw Krell (plateau biasing) Jeff Rowland (Class D amps) moving away from too much Class A enrichment and believed Class A was something of the past.
After I had the opportunity to possess amplifiers like the Threshold SA/1 and Levinson ML-2, I realized that for me the benefits outweighed the "penalty's".
I recently acquired a pair of fixed bias Krell KRS-200 mono poweramplifiers that are biased for approx. 180 Watts Class A RMS @ 8 Ohms
(375mA with 18 outputdevices = 364 Watts peak Class A and 182 Watts RMS)
I've read the technical articles from the PassLabs website:
- Leaving Class A and the Sweet Spot both written by Nelson Pass on the Class A subject.
My question is if the conclusions in those articles are also true for my Krell KRS-100 an amplifier that consumes approx. 650 Watts when idling, has comparable heatsinking and PSU and Class A ratings comparable with a PassLabs XA-160.5.
I'm not implying I bought a PassLabs quality amplifier, I didn't of course, but I'm just curious if the reasoning in those articles are true for my amps and any amplifier that is a high (fixed) biased amplifier?
Thanks in advance.
https://www.diyaudio.com/forums/attachment.php?attachmentid=935852&stc=1&d=1616763191
I saw Krell (plateau biasing) Jeff Rowland (Class D amps) moving away from too much Class A enrichment and believed Class A was something of the past.
After I had the opportunity to possess amplifiers like the Threshold SA/1 and Levinson ML-2, I realized that for me the benefits outweighed the "penalty's".
I recently acquired a pair of fixed bias Krell KRS-200 mono poweramplifiers that are biased for approx. 180 Watts Class A RMS @ 8 Ohms
(375mA with 18 outputdevices = 364 Watts peak Class A and 182 Watts RMS)
I've read the technical articles from the PassLabs website:
- Leaving Class A and the Sweet Spot both written by Nelson Pass on the Class A subject.
My question is if the conclusions in those articles are also true for my Krell KRS-100 an amplifier that consumes approx. 650 Watts when idling, has comparable heatsinking and PSU and Class A ratings comparable with a PassLabs XA-160.5.
I'm not implying I bought a PassLabs quality amplifier, I didn't of course, but I'm just curious if the reasoning in those articles are true for my amps and any amplifier that is a high (fixed) biased amplifier?
Thanks in advance.
https://www.diyaudio.com/forums/attachment.php?attachmentid=935852&stc=1&d=1616763191
Attachments
650Watts idling! That is obscene and should be illegal.
What a waste of enery.
Class D is up to 98% efficient with no crossover distortion (there is nothing to crossover) and extremely low harmonic distortion.
Why waste all that costly energy on old fashioned technology.
Class A went out with the demize of single ended valve amplifiers.
Still, ideal for winter time keeping your house warm
What a waste of enery.
Class D is up to 98% efficient with no crossover distortion (there is nothing to crossover) and extremely low harmonic distortion.
Why waste all that costly energy on old fashioned technology.
Class A went out with the demize of single ended valve amplifiers.
Still, ideal for winter time keeping your house warm
Why concern yourself with the personal tastes of other people? Some people like the sound they get with pure Class A amplifiers. Other people like the sound they get with pure class D amplifiers. Still others prefer Blameless Class B. It's what they like, but they are not you. Why not focus your efforts upon discovering what YOU like? And then build it DIY. Let others do as they wish, in pursuit of their own happiness.
Relevant book sold by Amazon
Relevant book sold by Amazon
"Class A went out with the demize of single ended valve amplifiers."
Demize means "Dead"?
I have one and I think they are very much alive?
The coming Pass VFET amp project also "smells" like something Single Ended?
Demize means "Dead"?
I have one and I think they are very much alive?
The coming Pass VFET amp project also "smells" like something Single Ended?
Why so rude
There are People loving CLASS D and there are People loving CLASS A OR CLASS B, leave the decision to them, what they want to use.
you are completely off the track if you think Class A stopped with the TUBES, more than BEFORE CLASS A COMES BACK.
A friend of mine is calling CLASS D " Amplifiers of the minimalists" Sorry but do you know that a real CLASS A uses less parts than a CLASS D?
Just one Question, what does the CLASS D Imply or mean to you..
Sorry, one more.. Can you hear DIGITAL?
Me not.. All analogue, since then if you need to change ANALOGUE to DIGITAL and DIGITAL TO ANALOGUE then a CHANGE of SIGNAL is guaranteed,
With CLASS A there you will not have that problem.. Converting forth and back and then SAMPLE AND HOLD, just that there is the need of sampling, that's already Loss of Quality. Sampling means inserting a portion which could not be fitted or found other ways as far as I know.
This started when the first COMPACT DISC came out..
And that's why the Audiophile use RECORDS..By the way, all Musicians who are in front of the MUSIC Trail they also RECORD, RECORDS for the Listeners, Mostly out of Business interest, but also because SOUND QUALITY is definitely better, Better may is the wrong word. say, more human
Just besides that CLASS A TUBE AMPS COST a manifold more than any class D.. And today's productions of Tube amps have increases very much, and also RECORDS have gone up in the past 4 years by 200%. So why, one then should listen to class D?
There is one Reason, because he likes the sound may or may not.. or because it's cheaper, or whatever, but exactly these reason has also those who listening to CLASS A and CLASS B etc. etc
Enjoy weekend
Regards Chris
Bern Switzerland.
There are People loving CLASS D and there are People loving CLASS A OR CLASS B, leave the decision to them, what they want to use.
you are completely off the track if you think Class A stopped with the TUBES, more than BEFORE CLASS A COMES BACK.
A friend of mine is calling CLASS D " Amplifiers of the minimalists" Sorry but do you know that a real CLASS A uses less parts than a CLASS D?
Just one Question, what does the CLASS D Imply or mean to you..
Sorry, one more.. Can you hear DIGITAL?
Me not.. All analogue, since then if you need to change ANALOGUE to DIGITAL and DIGITAL TO ANALOGUE then a CHANGE of SIGNAL is guaranteed,
With CLASS A there you will not have that problem.. Converting forth and back and then SAMPLE AND HOLD, just that there is the need of sampling, that's already Loss of Quality. Sampling means inserting a portion which could not be fitted or found other ways as far as I know.
This started when the first COMPACT DISC came out..
And that's why the Audiophile use RECORDS..By the way, all Musicians who are in front of the MUSIC Trail they also RECORD, RECORDS for the Listeners, Mostly out of Business interest, but also because SOUND QUALITY is definitely better, Better may is the wrong word. say, more human
Just besides that CLASS A TUBE AMPS COST a manifold more than any class D.. And today's productions of Tube amps have increases very much, and also RECORDS have gone up in the past 4 years by 200%. So why, one then should listen to class D?
There is one Reason, because he likes the sound may or may not.. or because it's cheaper, or whatever, but exactly these reason has also those who listening to CLASS A and CLASS B etc. etc
Enjoy weekend
Regards Chris
Bern Switzerland.
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my recipe is efficient and sensitive speakers, needing small power A Class amp
as long I'm paying my electrical bill, having moderate car mileage per year, taking care of waste and garbage, having my house decently isolated and using minimal amount of energy for heating, all LED bulbs etc .......... I don't care what other people think what's best
and I like that PL is making big A Class amps;
Rich Papa, Happy Papa, Happy Greedy Boyz
as long I'm paying my electrical bill, having moderate car mileage per year, taking care of waste and garbage, having my house decently isolated and using minimal amount of energy for heating, all LED bulbs etc .......... I don't care what other people think what's best
and I like that PL is making big A Class amps;
Rich Papa, Happy Papa, Happy Greedy Boyz
I’ve had and still have class A amps
I love the full body of sound and how warm the sound is coming from a class A, class D sound is just to dry for me.
Use what you like, and enjoy
I love the full body of sound and how warm the sound is coming from a class A, class D sound is just to dry for me.
Use what you like, and enjoy
There's some evidence to indicate that for most domestic speakers in small and medium size rooms, you would never need more than 40 watts of any kind of power, most of the time even a 10 watt unit would be enough.
At those kind of output levels, the dissipation and energy required to run a Class A amp are not a big issue, except in very hot climates (like ours)
At those kind of output levels, the dissipation and energy required to run a Class A amp are not a big issue, except in very hot climates (like ours)
All my systems are biamplified, with small classA amp for mids/tweeters, and classAB for woofers. No need to waste classA to power woofers.
Class D is purely analog, nothing to do with digital... It is a common misconception. Read this.
A change of signal is also guaranteed in analog btw, as you cannot go straight from the mic preamp of the recording to your amp... At least in digital, that "change" is not getting worse everytime you play your media.
I certainly didn't want to start a moral discussion about having these kind of Class A amplifiers. In my vicinity they build 50 windturbines last year and I pay more than 100% energy-tax over the kilowatts I have to pay to the energy company. I've tried te Class D amplifiers from JRDG (201's) and I did not like them. But maybe the current crop of Class D amps are better.
Still I hope I can get an answer to my original question if the two technical articles from the PassLabs website and their conclusions, are also valid for my Krell KRS-100's and every Class A amplifier biased in that way.
Thanks
Still I hope I can get an answer to my original question if the two technical articles from the PassLabs website and their conclusions, are also valid for my Krell KRS-100's and every Class A amplifier biased in that way.
Thanks
I don't quite understand how to waist power on Woofers?
Class A Amps, after switched on, always pull 100% of the power which these amps are designed for.
And it doesn't matter if these are tweeters or Mid-range, 5 watts are 5 watts. 10 Watts are 10 Watts, and if these amps are increasing current while more output Power is requested then these are not real CLASS A. CLASS A does not increase Current while increasing VOLUME.
This is because the CLASS A is always switched ON with MAX POWER, and most times a bit more then necessary. But I sure you know that.
Regards
Chris
RobertS61 - Sadly, that ship has sailed. Soon, I anticipate you'll be receiving unsolicited advice on speaker cables and caps. 
Are you asking if your Krell amplifier will "klunk"?
If so, here is a wonderful summary by AndrewT (R.I.P.) that might shed a bit of light.
Refurbished Krell KSA 100
Edit - My apologies. Wrong amp. I'll see if I can find something on the KRS-100
Are you asking if your Krell amplifier will "klunk"?
If so, here is a wonderful summary by AndrewT (R.I.P.) that might shed a bit of light.
Refurbished Krell KSA 100
Edit - My apologies. Wrong amp. I'll see if I can find something on the KRS-100
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In short yes!
BIAS is set to full output power from the moment you switch the amp on.
Everything else is not CLASS A.
Best is ask Mr. Pass
Take an AMPERE METER and SET IT UP IN SERIES with Plus RAIL,
Get yourself a DUMMY LOAD, connect to the Speaker Port binding posts.
Get yourself a Function Generator, set that Function Gen to 1khz Sine. Connect that Function Gen to input of the amp.
If Possible a SCOPE, and then switch on Scope, let it warm up for a few minutes.
Connect the Scope to output of that amp or parallel to Dummy load.Make sure that the SCOPE is Centered to 0VOLT and is in position DC
Switch on the AMPLIFIER.
Check the reading on the AMP METER.. and then open the volume on that Function Gen, increase till the SINE Wave start to clip. turn a little bit back that you get 100% of the output but not CLIP.
Now read the AMP METER AGAIN. if it stays the same as at the beginning then Highest BIAS Is the answer.
There is your ANSWER.
If this is now is not what you expect, then ask Mr. NELSON PASS, he is a very generous man, and will give you the answer.
And then you can be sure that this is as written in stone..
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wow, you are waaay overthinking it, I am not even going to try to reply
if I would want to power my 3 or 4 way speakers with classA amps, bi amplified, I would need two classA stereo amps (of four classA amp monoblocks)
but I use classAB to power my woofers, how is that not saving energy?
Hi
I think you misunderstand me.
For me there is no ENERGY SAVING when Listening to Music.
If you use Class A for Mid and High, so then why you use AB for low frequencies?
To get good Low Frequencies you need INSTANT POWER and this you have with CLASS A, because when you opening the VOLUME full power is already available.
AB will increase Power with opening the VOLUME, meaning has to build up POWER FIRST.
There is this small difference of CLASS A to all other..So for me this is not a waste.
This is what I meant.. I have about 10 or more CLASS A at home, and I also put it as ZEN MOD already had put it..
You see everyone should use what he likes and what fit's his needs.
And last but not least, you decide, for yourself, and it's not my right to try to change that, but I was curious about the word "Wastie class to power Woofers." there is never a waste, when you listening to CLASS A, other way, you would use the wrong amplifier if you find this as a waste.,.
<Quote> No need to waste classA to power woofers.</Quote>
Or I might I just don't understand it the right way.. No harm done..
BTW. A real good CLASS AB is at least as expensive as a CLASS A.
I think you misunderstand me.
For me there is no ENERGY SAVING when Listening to Music.
If you use Class A for Mid and High, so then why you use AB for low frequencies?
To get good Low Frequencies you need INSTANT POWER and this you have with CLASS A, because when you opening the VOLUME full power is already available.
AB will increase Power with opening the VOLUME, meaning has to build up POWER FIRST.
There is this small difference of CLASS A to all other..So for me this is not a waste.
This is what I meant.. I have about 10 or more CLASS A at home, and I also put it as ZEN MOD already had put it..
You see everyone should use what he likes and what fit's his needs.
And last but not least, you decide, for yourself, and it's not my right to try to change that, but I was curious about the word "Wastie class to power Woofers." there is never a waste, when you listening to CLASS A, other way, you would use the wrong amplifier if you find this as a waste.,.
<Quote> No need to waste classA to power woofers.</Quote>
Or I might I just don't understand it the right way.. No harm done..
BTW. A real good CLASS AB is at least as expensive as a CLASS A.
'I think you misunderstand me.
For me there is no ENERGY SAVING when Listening to Music.
If you use Class A for Mid and High, so then why you use AB for low frequencies?
To get good Low Frequencies you need INSTANT POWER and this you have with CLASS A, because when you opening the VOLUME full power is already available.
AB will increase Power with opening the VOLUME, meaning has to build up POWER FIRST.'
whaaat? what a load of nonsense
I am outa here...
For me there is no ENERGY SAVING when Listening to Music.
If you use Class A for Mid and High, so then why you use AB for low frequencies?
To get good Low Frequencies you need INSTANT POWER and this you have with CLASS A, because when you opening the VOLUME full power is already available.
AB will increase Power with opening the VOLUME, meaning has to build up POWER FIRST.'
whaaat? what a load of nonsense
I am outa here...
That's exactly what I've done:
https://www.diyaudio.com/forums/attachment.php?attachmentid=935953&stc=1&d=1616785284
I've cranked it up till 43,3 Volts (have a Threshold FET Eleven/g with indents on the volume, that's why that strange figure of 43.3 Volts was reached) and with the 7 Ohms I connected as load it is 250 Watts @ 7 Ohm and the AC uptake remains the same around 550 Watts.
https://www.diyaudio.com/forums/attachment.php?attachmentid=935957&stc=1&d=1616786080
So I believe it's Class A for it's 8 Ohm rating just like a XA-160.5, but my question is if that characteristic has the same benefits as stated about Class A in those two technical articles from the PassLabs website I mentioned?
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My statement is not a personal thought, it is fact. Class A produces alot of wasted heat, 'handy to keep your house warm in winter'.
People will do as they wish, that is all part of the human sychie.
I build both Hi Fi amplifiers and Instrument amplifiers for a living and have done professionally for over 40 years. My experience is wide and varied.
I thank you for your comment.