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Discovering pure Class A - It's true, not all Watts are created equal

hifinutt

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As I mentioned before several folks I know have had jh stuff for several years and bought at least 2 times . The chap who had my f5 bought a good many monoblocks specially commissioned for him
 

hifinutt

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This differs profoundly from my experience of Class A amplification, and is a very misleading generalisation - certainly not an accurate description of any Pass or Sugden designs I have had the pleasure of listening to - perhaps a "synergy" issue? I've never actually heard any Accuphase gear, though, so perhaps they're a bit more pipe and slippers - cue angry mob of offended Accuphase owners brandishing pitchforks....
The sugden a21se was one of the fastest tighest amps I have ever heard . Certainly not soft !!!
 

karlsushi

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This is a fascinating read if you have the time.

Some incredibly compelling arguments for why single-ended Class A has such a natural sound and some interesting points to address the ongoing debates surrounding measurements vs subjective listening.

And just so happens to be in relation to the amp I'm having built by JH ;)
 

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  • Pass Aleph 5 Manual.pdf
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Nopiano

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Quick update. The Aleph 5 has already been built by Joe and I will be collecting at the end of the month.

In his words 'it is sounding amazing' :)
That looks fabulous. Did you say £2,000? Is it the most ‘advanced’ Aleph model, as I see he has a single transformer version on eBay, but half the power and designated J?
 

karlsushi

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I chose the Aleph 5 because it is a single-ended design, but sporting double the output power of my much loved Aleph 3 (60W into 8 ohms Vs the Aleph 3's 30W). Both still pure Class A of course.

There are a number of different designs available, all of which can presumably be cloned due to the extensive information that Nelson Pass provides for each one. Ready made PCBs are also available for many of circuits from diyaudiostore.com which is directly affiliated with Mr Pass I believe.

The best place to start is probably the First Watt website where detailed manuals are provided for all of the First Watt designs: https://www.firstwatt.com/prod.html

The Aleph J I think is actually a newer design than the Aleph 5, but rated at 25W per channel. Details of the J are on that website, but being a design which pre-dates First Watt, the Aleph 5 I believe was originally sold under the Pass Labs name and whilst not on that website, is still available online as a Pass Labs manual (and which I've attached in one of my posts earlier on in this thread).
 
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avinunca1

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There doesn't seem to be any mention of Nelson Pass' intention with regard to his intellectual property. As i understand the situation, he set out to encourage the diy fraternity to build clones of First Watt designs no longer in production.
Surely he would take a dim view of constructors selling clones for profit on eBay or wherever however nicely they are built.
 

hifinutt

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yes when he started he used to mention it more blatently but now its more discrete . he really does some great stuff

nice F3 here if anyone interested

 

Nopiano

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avinunca1

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Don’t you wonder why it only lasted three months? It’s pretty puny too, unless you’ve ultra sensitive speakers.
It's not broken and it has more power than my Leak 20. Needs reasonably sensitive speakers - certainly not 'ultra sensitive'. I bet it sounds great with the right speakers.
 
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hifinutt

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Don’t you wonder why it only lasted three months? It’s pretty puny too, unless you’ve ultra sensitive speakers.
yes i often wonder why things dont last if they fly out the door . some owners like the heco direckt seller recently are very honest .folks change their mind i guess
 
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Nopiano

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yes i often wonder why things dont last if they fly out the door . some owners like the heco direckt seller recently are very honest .folks change their mind i guess
I can understand moving on from some speakers, but not why they were bought in the first place! TBF not everyone can hear first, so take a punt.
 

karlsushi

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Right, I figured it was time to update on my Joe Henry built Aleph 5 clone now that I have had it for a good month. Decided to add it here rather than start a new thread.

I haven't got time to write a full essay, so will try and be brief.

First things first, it is massive. Like, really big. And it weighs at least as much as it looks like it might. As in nearly a 2 person job. This is what it looked like initially when I had it on top of the unit:

DSC_0219.JPG

The unit being dwarfed next to it is a thoroughly decent-sized Denafrips Pontus II DAC. It has since been shuffled around (more on that below), but it simply couldn't stay on top of the unit in a living room with some decorum to be kept.

Regarding the sound though, it really couldn't be any more in contrast to its appearance. It is the smoothest and most relaxed sounding amp I have ever owned. Like melted butter on jazz and acoustic. But in the words of others when referring to single-ended Class A, it just sounds...right. Right in terms of timbre, right in terms of naturalness and right in terms of tone.

It also pushes everything back, so that the back walls behind the speakers have all but disappeared. Not something I've ever really experienced in my living room system.

All sounding perfect right?

Well, not quite sadly. Because in truth, it's not quite working out in that room! Gutted.

First thing to point out is that it is a pretty big and unhelpfully-shaped living room. It's 13ft x 25ft (so pretty bloody long) and unfortunately the speakers have to be positioned on one of the long walls, so the listening position is about 9ft from the speakers with a lot of room space either side. Not a great picture, but hopefully this helps to visualise:

DSC_0250.JPG

This means that, whilst there is a decent amount of direct sound from the speakers being reasonably close to the listening position, there is also a lot of lost sound energy into the wasted space either side of the room. As an aside, this also creates an issue with ceiling reflections because I have one almighty long flat and fairly low heighted ceiling. I have always suffered with treble glare in this room and I believe this is primarily why.

But going back to the main point about the room, it is apparent to me that in order to get up to party levels of music (which I do from time to time), the amp needs to pump out a lot of power.

Now, this is going to sound incredibly flippant based on the title of this thread, but it seems that 60W of pure Class A just ain't enough in this room and with my current accompanying equipment. Admittedly, not helped by the fact I am using a preamp with zero gain and some modestly efficient, but certainly not high sensitivity, speakers in the form of my 88dB Spendor A7's.

But before I decided I'd made a big mistake and needed to sell an amp I'd only just bought, I thought I'd give it a run in my second system (small room, near-field 89dB LS3 stand-mount speakers) and, well, there's no way I'm getting rid of it. In that system, it sounds utterly sublime. Very similar to the Aleph 3 I was already using in there, but just with a bit more of everything the Aleph 3 has, plus a bit of extra headroom from the doubling of power.

So it's staying in that system for now. Yes o.k, the amp is bigger than the speakers I'm using it to drive and may seem overkill, but it's going nowhere for now.

Which brings me back to the living room system and what to do.

Another similar amp, but with higher sensitivity speakers, or a more powerful amp? :unsure:

I do still enjoy my Nord Hypex Class D amp (which puts out 400W into 8 Ohms), which of course has had to go back in that system again, but I am also 100% decided that I prefer the sonic signature of the Aleph 5 than the Nord, so will inevitably want to do something about that when I can save up the funds.

400W of pure Class A anyone? :)
 

2010*zuma

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Yes I remember like it was yesterday discovering pure class A for the very first time...


It was a warehouse back in 88' this is an actual picture of me from a video camcorder that I only discovered last week.. Videoframe_20220410_200352_com.huawei.himovie.overseas.jpg Videoframe_20220410_200352_com.huawei.himovie.overseas.jpg Videoframe_20220410_200351_com.huawei.himovie.overseas.jpg Videoframe_20220410_200351_com.huawei.himovie.overseas.jpg [/ATTACH] Videoframe_20220410_200350_com.huawei.himovie.overseas.jpg 73140[/ATTACH]

.... Im not making this up... Im a baldi middle age man currently.

Back then I was a ponytail wearing free love brave new world soul🤪
 
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uzzy

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I've heard some good class A and some bad some valve and some SS. Like a lot of things, depends what your preferences are.

I still prefer my MOSFET AB power amps over pure class A for my taste in sound and music.

And scientifically, at least, Watts most definitely are Watts, assuming you are using the same standard to measure them 😉 thing is, at modest listening levels most of the time a lot of people are using <10w so really don't need all that much power.
I do not have knowledge of your P101 MOSFET .. but I do know that many Mosfet amps were biased heavily towards class A .. so my Hafler for example runs quite hot (with massive heat sinks) due to the biasing. I have a love for the Sugden A21 (a great reference point in a shop for comparing the sound of other amps) and whilst it has some balls when I had the Gales I chose the Hafler (due to the low efficiency and difficult impedance load). I guess I could get one now (current speakers are over 90db efficient) but as I love the sound I get I do not feel the need to go chasing.
I did have a hankering to change the amp and got a Nord Ice powered amp but in comparison to the Hafler it just did not do it for me. It seemed to have less detail in the mids and did not have the bass drive of the Hafler but it could just be that my ears are so in tune with my system.
 

rabski

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Another similar amp, but with higher sensitivity speakers, or a more powerful amp? :unsure:

I do still enjoy my Nord Hypex Class D amp (which puts out 400W into 8 Ohms), which of course has had to go back in that system again, but I am also 100% decided that I prefer the sonic signature of the Aleph 5 than the Nord, so will inevitably want to do something about that when I can save up the funds.

400W of pure Class A anyone? :)
If you like the presentation, then similar amp, higher sensitivity speakers.

There are practical reasons why you can only go so far with power outputs in pure class A, basically power usage and heat.
 

THOMO

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I do not think there is a Class A "sound".They vary as much in sound as Class A/B.
I agree the Class A Accuphase amps do sound fantastic but so do their Class A/B.
Some Class A amps I have owned /used sounded smooth and refined but also a bit boring and lacking in musical engagement.The First Watt F5 was like that as was an Aleph 30.
By far the best sounding amps I have used have been have been Class A/B-A Dartzeel copy and Bakoon Amp 5521.Both of those are zero negative feedback designs.
 

Psilonaught

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I had a class A Plinius amp for a while. It wasn't especially great TBH.

My Melody pentode amps were much better and not class A. Definitely depends on implementation.

High power class A triode amps anyone 😗
 

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