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DIY Amps: A Roadmap for Beginners (2017)

227 points| wallflower | 6 years ago |audioprimate.blog | reply

78 comments

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[+] 2bluesc|6 years ago|reply
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/

[1] https://spectrum.ieee.org/tech-history/silicon-revolution/nw...

[+] segfaultbuserr|6 years ago|reply
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!
[+] kurthr|6 years ago|reply
Thanks for this... I've done some double blind audiophile equipment testing and it's important to have a source to send folks to before and after.
[+] mikorym|6 years ago|reply
Source [1] is quite an amazing story. Has there been no update from NwAvGuy since that time (25 February 2014)?
[+] nullwasamistake|6 years ago|reply
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.

[+] antisemiotic|6 years ago|reply
>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.

There are people out there who buy rubidium clocks to time DACs and swear to deities that they can hear the difference.

[+] vonseel|6 years ago|reply
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.
[+] thatcat|6 years ago|reply
Thanks for explaining this, I had wondered why my sansa clip sounds so great.
[+] chadcmulligan|6 years ago|reply
indeed the days of having to spend a lot of money for hi fi audio are long gone, still people do though.
[+] kpgraham|6 years ago|reply
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.

[+] kakwa_|6 years ago|reply
The nice thing about these old tube amps is that the schematics are freely available (Fender ships a copy of the schematic with their amps). There are also quite simple in term of number of components.

However, there are dangerous, with 400/500V DC for the tubes. Definitely not something you should try without being extremely cautious and without previous experience.

On the topic of music hardware, another fun thing to build is effect pedals, these are much much safer, and permit to gain valuable experience with a soldering iron.

There are also a few kits available out there, either for effect pedals and tube amps.

For people in Europe, I can recommend https://www.musikding.de

* Tube amps: https://www.musikding.de/guitar-amp-kit-tube-amp-kit-valve-g... (I've built the A15 kit in the past, the components are a bit cheap, specially the power transformer, but it sounds quite nice, and makes for a great 15 Watts dual channels amp).

* They also sell a lot of pedal kits: https://www.musikding.de/guitar-effect-kits

They also sell parts (specially those a bit harder to find at a good price like footswitches, sockets, a wide variety of knobs etc).

Another shop I can recommend for components: https://www.banzaimusic.com/home.php

[+] dejv|6 years ago|reply
Tube amps are also much more dangerous than 9V battery operated headphone amps. For people that are just starting out those cmoy style projects are awesome. btw there is also 1W guitar amp in style of cmoy.
[+] wishinghand|6 years ago|reply
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.
[+] vvdcect|6 years ago|reply
Do you have any links to resources on building the said amps?
[+] renewedrebecca|6 years ago|reply
ax84.com is a great resource for guitar amp information too.
[+] mikorym|6 years ago|reply
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.

[+] JKCalhoun|6 years ago|reply
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…)

[+] vt102|6 years ago|reply
I know a little about tube guitar amps, and my understanding is that they are desired due to their “defects” compared to more accurate solid state transistors. I would assume headphone amps would want pristine amplification— why would you want tubes, then?
[+] ur--whale|6 years ago|reply
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?
[+] pthreads|6 years ago|reply
I love tube amps. Would like to start building my own. Could you please share your favorite resources if any? Thanks.
[+] k_sze|6 years ago|reply
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|6 years ago|reply
The DIY Audio Forum is a good place to start. 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.

[+] m0zg|6 years ago|reply
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.

[+] shereadsthenews|6 years ago|reply
Well building anything with tubes makes no sense at all but that doesn’t rule out making headphone amps. Many small devices are unable to drive many kinds of headphones so you need something to bridge that gap. The other reason you might have is devices that can drive your headphones but have a lot of coupled noise from nearby digital electronics. This goes for most laptops.

As an example I have a Zoom F4 portable recorder. It has a headphone output but it can’t drive 30-Ohm headphones worth a damn and even with high-impedance headphones there is audible noise that doesn’t exist on the recording itself. So if I want a realistic feedback on what I am recording I have to monitor through an external headphone amp.

[+] mb_72|6 years ago|reply
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.
[+] madengr|6 years ago|reply
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

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

https://www.madisoundspeakerstore.com/full-range-speaker-kit...

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

[+] microcolonel|6 years ago|reply
Class T wins. Choose a modulation frequency high enough and you won't need to worry about analog gain controls.