Class A Amplifier – Hype or Reality?

[magma]

Someone mention
Class A ?
India ?

Well I would say without a doubt one of the best ( I've heard)
Class A pure is built by First NOte Labs
( Kolkata )
These guys specialise in only class A
Their newer stuff is Class A SET

They are one of the best amp designers ( that i know of ) in the country


Here's some old stuff 8yrs ago
55 wats per channel all running in pure class A

My New Class A Amplifier - Make in India

Hi guys i just received my new amplifier last week Sharing some thoughts and pics about the same since its a made in india product that makes me proud to own designer and builder is an ex forum member "cranky" - in Kolkatta Below is the power amp that arrived last week heres the primary...

www.hifivision.com

Above is
Strictly my personal opinion only ( may even be biased(
But I've owned almost every iteration of their amps for the last 11 yrs ( in some form of another )

Btw
Invention audio
2lacs .
Seriously !!!

 

[Hari Iyer]

My pure class A is direct coupled, SET , Probably 3+3watts driving a 96dBSPL open baffle vintage speakers - amplifier is designed by @drlowmu in 2019.

 

[Prodigy]

Great to see Indian Designers to come up with Class A amps. Anywhere we can demo the amps by Firstnote @magma sir ? I see Sound Foundation’s contact details on the website. Possible for an audition anywhere in Bangalore?

 

[bhaskarcan]

My two friends bought an ACA because it was inexpensive and they each wanted to try it out, VS their highly developed 2A3 amps ( SE, DCed, LSES power supply ).

I would guess the purpose of the ACA is for Nelson to have an affordable product with which he can make money.

One of these two friends knows Nelson personally. He and Nelson occasionally talk amp circuits on the phone.

The use of nested Feedback is likely inherent in all of these Solid State designs Nelson does, independent of Model Designation.

Each of my friends independently came to the conclusion ( that their ACA needed to be sold to someone else ), and they kept their particular tube designs. Their tube amps have zero Negative Feedback, and all the other benefits inherent in their amps' unique design.

One has to look no further than the 2021 6005 stereo DIY amp thread on HFV, to discover an amp that exceeds those 2A3 amps the two fellows were using as a reference. I have personally heard all three amps.

One will NOT find these three amp's inherent design benefits, in other tube amplifiers currently existing.

Additionally, I personally think 2021's HFV 6005 stereo DIY amp out-performs their two 2A3 monoblock amps, and all-else existing world-wide, ...... and does so rather easily. ( For many good reasons, all previously provided. ) That..... is just my best guess.

Please make no mistake - when judging me and / or what I claim herein.

101 dB speakers, and higher, are required to play in this league. Mine are about 103 dB, Professional, not consumer quality.

Have fun, I sure am.

Jeff

Hello Jeff,
I hope you have at least gone through the ACA article by Nelson Pass before commenting on it and comparing it with your "highly developed" 2A3 amp.
Since obviously you have not read the article, I request you to kindly do so.
In the meanwhile, you are comparing your highly developed 2a3 amp with an amp designed by NP for the novice DIYers who doesn't even have skills to make a proper power supply. The ACA runs on Laptop brick power supply. Is the comparison justified at any level?
ACA is described by the designer as following:
Quote///
So Amp Camp Amp #1 is a discrete design using four transistors. It can be built for about the same cost as a chip amp and in the same amount of time. It will not measure as well as chip amps in some regards, but as a single-ended Class A design with minimal feedback it will sound good and get some high end audiophile respect.

We have to seriously consider safety as a constraint with regard to the power supply circuitry for the amplifier. We assume that most of the participants in this project do not have the skills to safely connect the components which make up an amplifier power supply to the AC power line.
///Unquote

Here is the link of the article for your kind perusal.

Amp Camp Amp #1

Introduction Do-It-Yourself audio is a great activity. Many major audio components are easily constructed and made to perform as well or better than what we see in the stores and at considerable savings. The process is educational and therapeutic and there are few greater satisfactions than...

www.diyaudio.com

And BTW, Mr Pass never sold a single ACA. It was solely designed for DIY.
There's no commercial ACA offering from any of the Pass companies. So again, him making money from ACA claim of yours also seems unsubstantiated.

Regards

 

[Dr.Gary]

Hello Jeff,
I hope you have at least gone through the ACA article by Nelson Pass before commenting on it and comparing it with your "highly developed" 2A3 amp.
Since obviously you have not read the article, I request you to kindly do so.
In the meanwhile, you are comparing your highly developed 2a3 amp with an amp designed by NP for the novice DIYers who doesn't even have skills to make a proper power supply. The ACA runs on Laptop brick power supply. Is the comparison justified at any level?
ACA is described by the designer as following:
Quote///
So Amp Camp Amp #1 is a discrete design using four transistors. It can be built for about the same cost as a chip amp and in the same amount of time. It will not measure as well as chip amps in some regards, but as a single-ended Class A design with minimal feedback it will sound good and get some high end audiophile respect.

We have to seriously consider safety as a constraint with regard to the power supply circuitry for the amplifier. We assume that most of the participants in this project do not have the skills to safely connect the components which make up an amplifier power supply to the AC power line.
///Unquote

Here is the link of the article for your kind perusal.

Amp Camp Amp #1

Introduction Do-It-Yourself audio is a great activity. Many major audio components are easily constructed and made to perform as well or better than what we see in the stores and at considerable savings. The process is educational and therapeutic and there are few greater satisfactions than...

www.diyaudio.com

And BTW, Mr Pass never sold a single ACA. It was solely designed for DIY.
There's no commercial ACA offering from any of the Pass companies. So again, him making money from ACA claim of yours also seems unsubstantiated.

Regards

Thank you for having the courage to call attention to Jeff Medwin's propensity to make totally unsubstantiated comments. While regrettable, it's a behavior that has been ongoing for a very long time. The following link provides an example of what may well constitute the worst of the worst. https://db.audioasylum.com/mhtml/m....i/search.mpl?forum=tubediy&searchtext=bravura

 

[drlowmu]

Hello Jeff,
I hope you have at least gone through the ACA article by Nelson Pass before commenting on it and comparing it with your "highly developed" 2A3 amp.
Since obviously you have not read the article, I request you to kindly do so.
In the meanwhile, you are comparing your highly developed 2a3 amp with an amp designed by NP for the novice DIYers who doesn't even have skills to make a proper power supply. The ACA runs on Laptop brick power supply. Is the comparison justified at any level?
ACA is described by the designer as following:
Quote///
So Amp Camp Amp #1 is a discrete design using four transistors. It can be built for about the same cost as a chip amp and in the same amount of time. It will not measure as well as chip amps in some regards, but as a single-ended Class A design with minimal feedback it will sound good and get some high end audiophile respect.

We have to seriously consider safety as a constraint with regard to the power supply circuitry for the amplifier. We assume that most of the participants in this project do not have the skills to safely connect the components which make up an amplifier power supply to the AC power line.
///Unquote

Here is the link of the article for your kind perusal.

Amp Camp Amp #1

Introduction Do-It-Yourself audio is a great activity. Many major audio components are easily constructed and made to perform as well or better than what we see in the stores and at considerable savings. The process is educational and therapeutic and there are few greater satisfactions than...

www.diyaudio.com

And BTW, Mr Pass never sold a single ACA. It was solely designed for DIY.
There's no commercial ACA offering from any of the Pass companies. So again, him making money from ACA claim of yours also seems unsubstantiated.

Regards

That is fine. I do not and will not read much at all about Nelson's doings.

If I thought it was better than what I do on my own, I would be a devotee and user.

Unlike his devotees,, I do not have any need to justify Nelson Pass's involvement in audio.

He's a good guy, but I do not need any of his gear. I am pleased with what I do. I hear it and know.

Jeff

 

[Pratyush J]

I have been shopping for speakers for some time and had listened to Platinum and Diamond Achals with Saptak at Indiqaudio. I had shared the feedback with Amit that Diamond's are fatiguing with Saptak. When the Class A amp came together, he invited me to come in and listen to Diamond's with Class A. I did a 1.5 hr audition session with the combo and what a change it was! Diamond's were no longer fatiguing and were really smooth. I had found Platinum's slightly lacking in bass and with this combo, I have the combo of heft and scale in the same set up. I have booked a Class A with Diamonds.

Absolutely true. My audition experience has been very similar. Their Class A plus Achals sounded great

 

[drlowmu]

I have been shopping for speakers for some time and had listened to Platinum and Diamond Achals with Saptak at Indiqaudio. I had shared the feedback with Amit that Diamond's are fatiguing with Saptak. When the Class A amp came together, he invited me to come in and listen to Diamond's with Class A. I did a 1.5 hr audition session with the combo and what a change it was! Diamond's were no longer fatiguing and were really smooth. I had found Platinum's slightly lacking in bass and with this combo, I have the combo of heft and scale in the same set up. I have booked a Class A with Diamonds.

Good posting. Your description above shows us all - what I keep on saying in this thread.

" We do not hear a speaker alone, but the speaker in combination with the best amplifier we have partnered with it. Both pieces, we will hear together. "

The design of the audio amplifier has a huge influence on the final listening result !!! Once you realize this co-dependent relationship, it behooves us to select a speaker that in advance, allows us to use the best-possible-sounding audio amplifier, to power our own speaker - amplifier combination.

This is a better way to get the highest-fidelity end-result possible. Yes, consider the best possible amp type, even before you buy the speaker.

If you start out with a large speaker radiating area, and a speaker sensitivity of 101 dB or more, you CAN effectively use a better sounding ( in time ) low powered amplifier, with ZERO negative feedback. This ........would be the smartest way to develop your own all-out High Fidelity system.

Stop compromising with solid state amps employing " minimal " feedback. What about the " zero " negative feedback listening alternatives?? Ever heard them, along with appropriate speaker loads?? .

If all you have heard your life, up to now, is solid state amps, with varying degrees of nested and / or negative feedbacks as their circuitry, how do you even know what is possible.?

QUESTION :

How much of a stain do you want to see and, in-public, wear, - on your brand new white shirt and bright silk tie??

" Minimal....... or......... zero " ???

Even if one's clothing choice uses a better quality of silk, the stain is still part of the viewable ( audible ) presentation. Not too desirable, especially when a proper speaker choice in the first place ( 101 dB sensitivity ) avoids the issue.

Make a single wrong initial choice, and you go on to spend your time, money and remaining audio life, compounding your initial error.

THINK about what I am saying. I am confident in the result, both ways. I have played this audio game over the decades, both ways !!! Good luck. Have fun.

Jeff

 

[Pratyush J]

Someone mention
Class A ?
India ?

Well I would say without a doubt one of the best ( I've heard)
Class A pure is built by First NOte Labs
( Kolkata )
These guys specialise in only class A
Their newer stuff is Class A SET

They are one of the best amp designers ( that i know of ) in the country


Here's some old stuff 8yrs ago
55 wats per channel all running in pure class A

My New Class A Amplifier - Make in India

Hi guys i just received my new amplifier last week Sharing some thoughts and pics about the same since its a made in india product that makes me proud to own designer and builder is an ex forum member "cranky" - in Kolkatta Below is the power amp that arrived last week heres the primary...

www.hifivision.com

Above is
Strictly my personal opinion only ( may even be biased(
But I've owned almost every iteration of their amps for the last 11 yrs ( in some form of another )

Btw
Invention audio
2lacs .
Seriously !!!

4 - 5 months of FNL delivery period is way too high. Sangram promised to share pictures this week

 

[magma]

4 - 5 months of FNL delivery period is way too high. Sangram promised to share pictures this week

Yes
Unfortunately
That is true

But that's unavoidable because of their business model of custom building only

Each amp is custom built as per clinet need
They even design a circuit if the client so requests one

Please understand
There is a lot of difference
Between going class A
20-25W

And
Going
55 W


For example
One of the amps on order
Has

21 kg heatsinks 24 inches long
10.2 kgs of copper

So the amp is 31 kgs of JUST heat dissipation items - which they say imperative to keep the transistors cool under 55 degrees
Which automatically allows them to bias the transistors at insane levels . Higher the bias and maintaining the transistors at optimum operating temp is the key

Hell even the front plate is milled for head dissipation since they use luhndals for smoothening the output

Now this amp is 20 inche wide and 24 inch
Deep

Obviously everyone would not have this kind of space

Andnthats why the custom building
And that's why the time period

 

[Pratyush J]

Yes
Unfortunately
That is true

But that's unavoidable because of their business model of custom building only

Each amp is custom built as per clinet need
They even design a circuit if the client so requests one

Please understand
There is a lot of difference
Between going class A
20-25W

And
Going
55 W


For example
One of the amps on order
Has

21 kg heatsinks 24 inches long
10.2 kgs of copper

So the amp is 31 kgs of JUST heat dissipation items - which they say imperative to keep the transistors cool under 55 degrees
Which automatically allows them to bias the transistors at insane levels . Higher the bias and maintaining the transistors at optimum operating temp is the key

Hell even the front plate is milled for head dissipation since they use luhndals for smoothening the output

Now this amp is 20 inche wide and 24 inch
Deep

Obviously everyone would not have this kind of space

Andnthats why the custom building
And that's why the time period

I had good email exchanges with him and appreciate the custom efforts the team is putting in. From the perspective of the customer, most people may not be able to wait for four to five months. Ideally, I would have expected a short wait time for a standard specs and additional time for custom design. Anyways, I'm eagerly expecting the photos he promised.

 

[bhaskarcan]

That is fine. I do not and will not read much at all about Nelson's doings.

If I thought it was better than what I do on my own, I would be a devotee and user.

Unlike his devotees,, I do not have any need to justify Nelson Pass's involvement in audio.

He's a good guy, but I do not need any of his gear. I am pleased with what I do. I hear it and know.

Jeff

Hello Jeff,

Thanks a lot for your clarification that you don't "read about" or "need" any Pass DIY design.
And the fact that you chose to compare your "highly Developed" amp with a design "for the novice", shows your ignorance about Pass's DIY designs and pros n cons thereof.

What I am very surprised that even your good friend, who has the great privilege of discussing amp designs personally with NP, chose his "the most for novice" design for himself too, instead of other so many more advanced offerings !!

On the other hand, if you look around here in HiFiVision, you'll find many novice members as well as very very experienced and respected members have made various DIY Pass designs and have been contently listening to them for almost a decade. So irrespective of their topology and design philosophy(and their weakness, as you claim), Pass DIY amp designs have been able to convince both the new and experienced DIYers of it's good sound for a long time now.

Since you are a very respectable member here and many other members follow your highly knowledgeable advices, I humbly request you to kindly refrain from commenting on something you are not fully conversant with. It consequently lowers your creditability on other matters that you comment. On a lovely platform like HFV, highly prejudiced personal opinions do not always ring positive bells.

I don't want to disturb this nice classA discussion any further, hence....

Regards

 

[drlowmu]

Hello Jeff,

Thanks a lot for your clarification that you don't "read about" or "need" any Pass DIY design.
And the fact that you chose to compare your "highly Developed" amp with a design "for the novice", shows your ignorance about Pass's DIY designs and pros n cons thereof.

What I am very surprised that even your good friend, who has the great privilege of discussing amp designs personally with NP, chose his "the most for novice" design for himself too, instead of other so many more advanced offerings !!

On the other hand, if you look around here in HiFiVision, you'll find many novice members as well as very very experienced and respected members have made various DIY Pass designs and have been contently listening to them for almost a decade. So irrespective of their topology and design philosophy(and their weakness, as you claim), Pass DIY amp designs have been able to convince both the new and experienced DIYers of it's good sound for a long time now.

Since you are a very respectable member here and many other members follow your highly knowledgeable advices, I humbly request you to kindly refrain from commenting on something you are not fully conversant with. It consequently lowers your creditability on other matters that you comment. On a lovely platform like HFV, highly prejudiced personal opinions do not always ring positive bells.

I don't want to disturb this nice classA discussion any further, hence....

Regards

You made some good points, in a very kindly manner. Bravo. I am not here to argue. ' Will stand by my speaker - amplifier co-dependency. It is hard to ignore that, and it transcends these more minor matters. Thanks.

Best wishes.

Jeff

 

[amrutmhatre90]

I am building the Nelson Pass ACA from parts sourced all around with a SMPS, not finding time to get chassis made yet.

 

[Yogesh]

I am building the Nelson Pass ACA from parts sourced all around with a SMPS, not finding time to get chassis made yet.

Good Luck with the build!

BTW, You look like Anil Kapoor!

 

[jmascreen]

I am building the Nelson Pass ACA from parts sourced all around with a SMPS, not finding time to get chassis made yet.

View attachment 71028

Is this the new 1.8 version?

 

[bhooshaniyer]

Im using a F5 turbo based class A amp from First Note Labs to drive Harbeth P3ESR.

Nice where are you based out of?

 

[Subbu68]

I built a pair of ACA 1.8. Now my Elekit TU8200 SE is resting. Running ACAs in bridged mono was a revelation. And with a DIY cardboard OB (temporary) Ahuja 12FRX it is definitely a joy to listen. At the same time with the same source and in the same room, Elekit TU8200 (SE Ultra-linear mode) and Klipsh Heresy III sound pale.

 

[himadri]

Nice where are you based out of?

From Chattisgarh.

 

[drlowmu]

I built a pair of ACA 1.8. Now my Elekit TU8200 SE is resting. Running ACAs in bridged mono was a revelation. And with a DIY cardboard OB (temporary) Ahuja 12FRX it is definitely a joy to listen. At the same time with the same source and in the same room, Elekit TU8200 (SE Ultra-linear mode) and Klipsh Heresy III sound pale.

Yes, of course the Elekit TU8200 sounded " pale. "

You are comparing a cancerous amplifier implementation............ to perhaps a polio audio amplifier.

Several months ago you were P.M.ed. It was suggested to you that the Elekit TU8200 was built to a low price point, and that it's resistors in KEY spots ( Ra and Rk - as a great example ) sorely needed upgrading.

Why swap gear all the time - - - - - fix and optimize it !!! DIY.

Apply thought please - - - - - get your audio money's worth. Obtain listening satisfaction.

Jeff

Opening a can of worms again: Why Tubes sound better

On a different note, Hari and Jeff - I have been thinking of getting back into DIY amps and building myself a slightly more robust SET amp than my Loftin-White 2A3. Either 300B or something even more muscular (approaching 10-12W or so, perhaps). Got any suggested circuits to check out...

www.hifivision.com