Reference DIY amplifiers

What do you say about making a list with reference DIY amplifiers?

I've seen lots of people that are searching for the "best" amplifier schematic. It would be useful for them(me included) to have a list with all of the DIY amplifiers that are the most popular around DIY builders and that can compete with high-end commercial ones.
A little review about it's design/overall sound would make the choosing easier.
 
horus said:
What do you say about making a list with reference DIY amplifiers?

A little review about it's design/overall sound would make the choosing easier.
.

the first amp that comes into my mind is:

Professor (in electronics) Leach amplifier ( or amplifiers, as he has got a couple of variants )
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Link, with description build instructions, schematic:
W. Marshall Leach, Jr., Professor
Georgia Institute of Technology
School of Electrical and Computer Engineering


http://users.ece.gatech.edu/~mleach/audiothings.html

.
# The Leach Amp Plans - The latest version of the Low TIM amplifier that I published long ago in Audio magazine.

# The Leach SuperAmp Plans - Plans for the Double Barrelled Amplifier that I published long ago in Audio magazine.

# Construct a Wide Bandwidth Preamp - An article I wrote for the Feb. '77 issue of Audio magazine that many people have asked me to post.
.

Review/Opinion:
I can not give a personal review. As I have not built one yet.
But there are many others at forum, THAT CAN!
Because there are 1.000 happy builders of Professor Leach amplifiers.


Regards
lineup
Lineup Audio
http://lineup.awardspace.com/




This image shows
one of his student's version of ' Low TIM Leach amplifier '.
Student Dan Leverett's amplifier:
 

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You gotta figure that the "chip amps" would be in there somewhere.

Google "LM3886 chipamp" and you're bound to see twenty variants. Which one is the reference? I wouldn't hazard a guess or offer an opinion. Most all approach mathematical perfection from the standpoint of amplification and are very simple to build.

Then there's the Alephs from the master himself.

There will be many other suggestions... SKA, Class D Tripath based, Randy Sloan's designs. Too many to mention.
 
chipco3434 said:
You gotta figure that the "chip amps" would be in there somewhere.
.

No. 🙂
As we all know there are no chips in Leach Amp.

There is not even one MOSFET to find in Leach 'LowTIM' Amp.

TIM means TransInterModulation, and is a form of distortion
that is said to be more harmful to sound, as we hear it,
than for example THD, harmonics distortion.

Professor Leach Amplifier, is from beginning an attempt to design amplifier
with LOW such distortion.
And without measuring it myself, I have no doubt,
that these Leach amplifiers have lower TIM than most other amplifiers.
Otherwise, why publish such a failure.
And what I know, professors normally does not do this 😉


About MOSFET.
Mr Leach explains why he did not use them in his amplifier at the time
he developed this amplifier.
He even performed tests with FET Output

Why not another configuration of output stage?
He answers some questions/suggestions he has got for alternatives output.
And explains why he stayed
using a rather common Triple Darlington arrangement.


New Year 2007
lineup
Lineup Audio Lab

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😎 😎
See my attachement for details of professor Leach power amplifier output stage.
The rest of a long story about a very good amplifier
and all the many details, you can read for free at:
The Leach Amplifier ( LowTIM )


* fotenote.
PMA ( Pavel Macura, another member here)
has suggested a new kind of test signal for audio amplifiers,
that shows more than only harmonic distortion.
Among this, I think, Intermodulation distortion within amplifiers.
 

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Yes, but what reference do we use for Leach's design itself?

I say this as one who has been building and using his amplifiers since the late 70's. I've never read any 'audiophile' reviews or direct comparisons to high-end (read: expen$ive) amplifiers. I don't expect Leach's designs to equal the very best; it's simply the best I can afford!

I'm rather pleased with the current design and haven't found any other designs compelling enough to attempt a project with them. I will probably try a Pass MOSFET Class A design at some point, but that's not a really practical design for me. Maybe a lateral FET Class AB design, but but both are more as an exercise in working with MOSFETs. To date, I have happily ignored Class D, and chip amps haven't met all my needs nor are they especially interesting to work with.

I have a tube amplifier project, which is on hold because I can't spare the money to buy quality output transformers. 🙁

There are a million ways to design an audio amplifier; some of them are better than most and it's sorting through the almost-infinite design choices that makes the subject fascinating to me.

I've read both of Self's and Sloan's books and they were very informative, though I'd rather >build< Sloan's designs. And I'm still tweaking my existing amplifier, and wishing I could design and build a professional-quality amplifier based on Leach's design. Alas, I have no access to a sheet metal shop and tools any more, and not much budget for proper heatsinks, transformers, and a professional chassis.
 
Summary to date:

Leach Amp(s)
Krell clones (KSA 50/100)
Chipamps (LM3886/LM4780 et al)
PassDIY (Aleph et al)
EPS (Rod Elliot) P3A

It looks to me like the list consists of the most readily available complete designs with documentation; which says more about accessibility than sound.

I would personally like to build Jens' Leach version, but the documentation for it is uncompiled. And there are no more boards available to my knowledge, just Gerber files. So if anyone wants to get a group buy going on that, let me know.

Has anyone built a Slone amp? Did it sound good?

Which DIY tube designs are 'popular'? I'm afraid of the budget consequences for tube projects myself.

..Todd
 
chipco3434 said:
I think you have mistaken my comments.

Chipamps are "in there" was meant to indicate that they would be present in "the reference list".

I see.
Yes, I read you wrong.

Sure, you are right.
We can't forget the original LM3875 Gainclone concept, by Thorsten.
Using the LM3875 power Op-Amp in inverted set up.

🙂
1000-nds of builders can never be 100% wrong!

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pinkmouse:
Don't forget MikeB's Symasym.

Absolutely!
I have pointed out many times
that MikeB SymaSym is a very good amplifier and project.

It is for me, the true raw model of how a great DIY amplifier project should be.
And what great designs a joint effort of good diy persons can accomplish.


Regards
lineup
 
pinkmouse said:
the best designs do tend to have the best documentation, simply because more people have built them.

The odd one out there is Slone, whose documentation belittles most others, yet I've never heard anyone ever say they've built one. I would probably attribute that DIY unpopularity to the negative commentary his circuits have elicited by the gurus here. That has certainly caused me to hesitate. I'm anxious to see the outcome of the current Figure 11.4/11.6 modification PCB threads going on here.

..Todd
 
.

Nelson Pass was mentioned.
Of course he should have,
at least, his 2 most popular amplifiers on this list.


The list of reference diy audio amplifiers.

I wonder if not The Original ZEN Class A would take one place?
If we consider number of built exemplars as a criteria
of a really good amplifier.
An amplifier that will in 90% of cases give very satisfying result and pleasing sound.


lineup
 
taj said:


The odd one out there is Slone, whose documentation belittles most others, yet I've never heard anyone ever say they've built one. I would probably attribute that DIY unpopularity to the negative commentary his circuits have elicited by the gurus here. That has certainly caused me to hesitate. I'm anxious to see the outcome of the current Figure 11.4/11.6 modification PCB threads going on here.

..Todd


Even though I do not know the details of Randy Slone amplifiers
I am a strong believer in his amplifiers are very good.
Anyone dare to write and publish books in this subject
would certainly posses great knowledge.

The problem why his constructions are not more 'popular',
I think is the fact,
that he had not openly and freely published any one of his best projects at internet.
If only he would do so, even only one of his great amplifiers,
I am sure people would build and mention him more often.
Because I have no doubt his amplifiers are very good.


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This is a fact, in my opinion:
Most DIY people do not order things that cost money - books or kits.
DIY community is basically "an open source thing".
It is about sharing without charging money.

And if ever want some money, it is with 'no profit prices'.


That it is not impossible to share some designs (in fact very many!)
and still make good money
has been shown by Nelson Pass.

In this detail, we can say, he has been more clever, than Slone.
But each designer make his own choice.
And do it his own way.


lineup
 
To me, a reference amp is not necessarily the best amp
(probably no such thing) but a reliable high quality amp
with a known characteristic. It's very important to live with
a familiar equipment environment, or it's very tough to make
reliable judgments about a component change.

😎
 
I went through a short-lived phase where I bought only big, thick books to read. My reasoning was that if somone went to the trouble to write so much stuff, and the editors passed it, and the printers printed it, and the stores sold it, that it must be a good book.
Boy, was I ever wrong!
Deciding that an amplifier design is "good" simply because it has a lot of documentation could lead to similar disappointment.
I don't think you'll arrive at a consensus on "the" reference amp. For that matter, I imagine that it would be difficult to narrow it down to a top five list. A top ten list might be doable, but it would take a lot of haggling.
Several problems arise. One is that few people build more than one or two amps...ever. As a result, they (if they're honest) can have no valid opinion on any of the other designs out there. Furthermore, most people are tickled pink if what they've built even turns on without smoking. If music comes out, they're over the moon. From then on, that's their favorite amp, come what may. They will recommend it over all others, just because they were able to successfully build it.
My prediction is this: This thread will not produce a "reference amp" in the sound quality sense. It will be a popularity contest--which is not at all the same thing as choosing a circuit that is reference quality.
Take Nelson's original Zen. Thousands upon thousands have been built. It's a simple, honest amplifier. A learning exercise. One that was never meant to be taken as more than it is. Yet people have devoted inordinate amounts of time and energy to "debunking" the "myth" of the Zen. Others have made it their life's work to take it to the masses, preaching the gospel of Zen-ness. Any amplifier with that many adherents (and detractors, which in the perverse world of human psychology, lend legitimacy to any endeavor) will generate a huge number of votes, regardless of sound quality.
Yet I doubt that anyone, Nelson least of all, would nominate it as a reference in any sense other than as a known quantity. It's only a starter project, from one point of view. From another vantage, it's a stepping stone to the Aleph topology. Either way, it's just an everymans' amp; a Volksamp, if you will (ahem), not a be-all, end-all touchstone for sonic quality.
Chose a circuit. Build it. Check it carefully. Turn it on. Listen to the music. Be happy.

Grey