
DIY Amps: A Roadmap for Beginners (2017) - wallflower
https://audioprimate.blog/2017/06/17/diy-a-roadmap-for-beginners/
======
2bluesc
My favorite audio resource for those designing or evaluating audio amps and
DACs is NwAvGuy's blog[0]. The blog posts explain what performance parameters
matter, what don't, and evaluates the performance of various products and
components.

Equally interesting is the mysterious story about the anonymous author himself
[1]

[0] [http://nwavguy.blogspot.com/](http://nwavguy.blogspot.com/)

[1] [https://spectrum.ieee.org/tech-history/silicon-
revolution/nw...](https://spectrum.ieee.org/tech-history/silicon-
revolution/nwavguy-the-audio-genius-who-vanished.amp.html)

~~~
segfaultbuserr
I have one Objective-2 amplifier right now on my desktop. Great fidelity,
reliable and robust. It's the best DIY project I've ever done. Thanks NwAvGuy!

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nullwasamistake
A neat hobby in the nostalgia sense but I'm convinced many audiophiles are
misled in the idea of audio quality.

You can build something with a mathematically perfect decode and EQ using a
raspberry pi. You want digital all the way to final amp stage.

For the amp stage (especially at low power headphone levels) the best amp
option is a nice dedicated amp chip. For a few dollars and little external
circuitry you can get a chip that will put out 10 watts into a sub ohm load
with less than 1% THD. Class D too so it uses ~1/2 the power.

Good example, the old discontinued Sansa Clip, a $20 mp3 player the size of a
tic tac box, has one of the best headphone amps tested. Combine it with
rockbox firmware and you have a super practical headphone amp that will rival
anything money can buy.

~~~
vonseel
I'm curious how something like the headphone amps or what you mentioned
compares to the headphone outputs on a high-end audio interface, e.g. the RME
Fireface line or similar recording products.

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atoav
I have a Fireface and never had only the slightest issue with the headphone
outputs.

As somebody who understands quite a bit about analog circuits and has seen
Firefaces from the inside I would definitly trust RME on that one, this thing
is beautifully engineered

~~~
vonseel
:) love my fireface

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kpgraham
I've built a half dozen Fender Bassmans and a few Fender Super amps over the
years. I thought the article would be about this kind of amp building, but
evidently not many hacker news readers play blues harp through a tube amp.

Low tech tube amps are quite easy to build, although they cost a few hundred
because the transformers, chassis and tubes can be pricey and the cabs and
speakers aren't cheap. The results are great, though, and I'd say go for it if
you are thinking about trying.

Get everything you need from Tubes and More dot com or eBay.

~~~
wishinghand
Are Bassman amps actually better at reproducing and projecting lower
frequencies? I have a fender amp for my regular electric, and a bass amp for
my bass guitar. I also have a baritone and wanted an amp for in between.

~~~
fuzzfactor
Originally the Bassman was a 50 watt amplifier with a pair of 6L6 tubes, this
is enough power to allow a solid-body bass guitar to play cleanly only about
as loud as a regular acoustic string bass.

For bass guitar, there was no need for reverb or tremolo so those tube effects
were not included on Bassmans. 6-string guitarists sometimes found these
Bassmans more gainful at maximum volume than the non-bass Fenders having
equivalent power and tube complement. A single pair of 6L6 (about 50W) for
guitar will be loud enough to keep up with an acoustic drum kit for lots of
blues and soft rock, while bass guitar actually needs about 300W.

With a loud drum kit and a heavy-hitting hard rock acoustic drummer, then I
naturally recommend a 100W fullstack for guitar and 400W for bass.

The circuitry of the Bassman is not designed for big differences in frequency
coverage compared to the non-bass vintage Fenders. The Bassman was primarily a
regular no-frills 50W head, and for actual bass use within its power level
(like in studios) it achieved lower lows because of use with a closed-back
cabinet.

~~~
wishinghand
Thanks for helping explain the name and history.

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mikorym
In South Africa almost all of our electronics are imported. Given the high
amounts of unemployment, the technical recession, lack of secondary industries
and manifacturing, the brain drain and scarcity of technical skills, etc., I
would really like to see something like this develop into a viable business.

Of course after that it would not be DIY anymore, but I like the spirit of
learning and productivity which at the same time would be refreshing to see it
developed into a viable product.

If you buy a high end powered speaker or amp here, expect to pay 50% more that
the price you see on Amazon. So, you basically have a 50% profit margin even
if your cost is equal to the _sales_ (!) price in the US.

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JKCalhoun
Happy to see a couple of tube amps among the kit listings.

I've enjoyed building many, many tube amplifiers in the past two decades or
so. Initially they were kits, later I did rolled my own point-to-point amps
and later still laid out my own PCB's for some PCB-based tube amps.

While the high voltages might seem intimidating (safety-wise) I hope that
doesn't keep people from pursuing this class of amplifiers. If you're smart
about it, you'll be okay. And there is nothing like the sweet music of non-
quantum sound amplification.

(When consider that my other hobby involves a table saw I'm beginning to
wonder what might be behind some of my life choices…)

~~~
ur--whale
The age old question: besides the obvious aesthetic attractiveness, is there
really any kind of objective advantages to tube-based audio amps as opposed to
solid-state semiconductor based ones?

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sound1
In audio most objectivists believe that currently known measurements
(frequency response, power handling abilities, THD, PSSR, other non linear
distortions, noise floor, etc.) can 100% conclusively define subjective sound.
But then on the flip side there are very reputable people (eg. Paul McGowan
from PS audio) agree that we may not have figured out all measurements
necessary to nail down subjective audio quality. It is upto the ears of the
listeners and their exposure to super high end audio to decide whether that is
true.

I fall in the camp that thinks we haven't fully figured out what conclusively
decides subjective sound quality. It makes things much more interesting and
open to more research to settle debates on solid state vs tube, sigma-delta vs
r2r dacs, full range driver vs other speaker configurations,
cables/interconnects/power-cords matter or not and things like that).

Some interesting links (I don't endorse what these guys are saying but find
them VERY interesting):

About DACs:
[http://www.streamplayer.io/v1/sharing?v=8Mn5PrnZV-k](http://www.streamplayer.io/v1/sharing?v=8Mn5PrnZV-k)

About whether audio power cables make a difference (Ask Paul from PS audio):
[http://www.streamplayer.io/v1/sharing?v=8QuToO9JUfw](http://www.streamplayer.io/v1/sharing?v=8QuToO9JUfw)

~~~
WhitneyLand
This measurability nonsense is a red herring.

Think about it, the question can easily be answered by blind A/B testing using
real listeners with varying aptitude for discerning any differences and the
qualities.

Over the years people have tried and failed often to show much difference,
when tests were done with proper controls and with scientific rigor.

To be fair I haven't read up on the subject recently so if there's anything
current that shows otherwise I'd be glad to read a link to a paper from a
credible source.

~~~
1kGarand
False.

Rigorous double blind a/b/c/d tests using real listeners has been performed,
and the research has been published in peer reviewed journals since the 80's.

What has happened is that most of the audiophile community saw research as a
threat to their revenue streams and actively FUD around it. And the audio
engineering community has simply moved on.

Here is a talk that could be very informative.
[https://www.youtube.com/watch?v=zrpUDuUtxPM](https://www.youtube.com/watch?v=zrpUDuUtxPM)

His book is worth a read as well.

~~~
WhitneyLand
What's one thing I said that was false?

I said studies have been done that failed to show any difference, that's
absolutely true.

I said I was open to hearing about recent papers published showing otherwise,
yet you've provided zero links to a peer reviewed paper. You offer a Youtube
video? If it's a video about research can we just skip to a direct link to the
science? Citation please?

I said it's not necessary to know if current testing equipment can detect
differences, _to know if people can tell the difference_. True.

Where are the rigorous double blind studies, with full disclosure, conducted
with no conflicts of interest in funding or affiliation?

And of course I assume we want to stay on topic and look at research that
isolate amplifiers for some tests, not conflate them with moving parts such as
speakers.

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madengr
I built this stereo amp kit a few months ago. Uses single ended 300B tubes
with class A bias. Very high quality kit and manual, though I expected that
from Japan. Fed directly with a CD player.

[https://www.elekit.co.jp/en/product/TU-8600R](https://www.elekit.co.jp/en/product/TU-8600R)

Also built some single driver, folded horn speaker kits. These pair will with
the tube amp.

[https://www.madisoundspeakerstore.com/full-range-speaker-
kit...](https://www.madisoundspeakerstore.com/full-range-speaker-kits/fostex-
bk-12m-folded-horn-kit-pair/)

I pretty much only listen to string quartets with this setup, and it sounds
great.

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k_sze
Are there good resources for DIY amps for stereo speakers? Are those much
harder/more dangerous to build than headphone amps? I have a pair of KEF Q100
bookshelf speakers that are still collecting dust.

~~~
swimfar
The DIY Audio Forum is a good place to start.
[https://www.diyaudio.com/forums/index.php](https://www.diyaudio.com/forums/index.php)

Some speaker amps will use mains power and transformers, which means working
with high voltage which can be dangerous. But there are some designs which use
external purchased power supplies which provide a lower voltage.

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m0zg
Building headphone amps doesn't make any sense, IMO. You are not even going to
outdo a $1 opamp with all this tube stuff. For headphone amp I use a Mackie
Onyx mixer that I bought used on ebay for $80. It also includes a bunch of
ADCs and, you know, the entire mixer. And it's more similar to the stuff that
was used when actually mixing the songs I listen to.

Where tube stuff still _does_ make sense is guitar amplification, where
particular flavors of distortion and frequency response nonlinearities are a
feature, not a bug.

~~~
mb_72
These days modelling (Helix etc) has reached the point where tube amps, cabs
and individual FX pedals can be replaced by a single piece of hardware. As a
bass player I ditched my SVT and individual pedals in favour of a Helix Stomp;
it's the best musical purchase I've ever made.

~~~
vonseel
Guitar/bass player here. I own a few tube guitar amps (Fender Blues Jr, Peavey
Ultra 410) and also have a vintage 70s Ampeg V4b. For nearly 100% of my daily
playing and recording needs I use Helix Native; it's simply easier, more
versatile, and sounds better than anything I can do with my real amps.

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microcolonel
Class T wins. Choose a modulation frequency high enough and you won't need to
worry about analog gain controls.

