• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Newbie Questions

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Hello all!
I am a complete newbie to the world of do it yourself electronics, and I have a few basic questions, so bear with me please. I want to build a tube headphone amp to power my Senn HD600's. I have minimal experience building electronics, but I know a very smart person who could help me along the way. Am I crazy to try to enter the world of electronics through amps? Through tubes? Also, are there any kits for newbies like me? Thanks for any and all help that anyone can provide!!
Blake
 
Hi BlakeB395;

As I type this, I'm listening to my Senn 600's through a homebuilt valve amp. Yes, it's do-able (and worthwhile)!

>>>...Am I crazy to try to enter the world of electronics through amps?...<<<

Not crazy at all. Amplification circuits range in complexity from multistage monsters with nested NFB loops all over the place to simple single ended designs (the simplest being "spud" amps - one gainstage and that's it!). For what it's worth, headphone amps are frequently some of the easiest to build, since they do not introduce the complications that can arise in high output power designs. Headphone amps are also a good starting place, since the cost of parts is less than in full powered amps - thus there is less economic risk attached to the project.

>>>...Through tubes?...<<<

Here the answer is less clear cut. Valve ("tube") designs tend to be very simple - the only thing generally simpler would be op-amp designs - but on the other hand valve electronics can be rather unforgiving due to dangerous high voltages that are present. Before you embark upon building valve circuits, you MUST read up on correct safety procedures and follow them religiously, so that you will not risk electrocution. The scary stuff aside, many valve circuits are VERY simple so they are easy to understand. However, they are ALWAYS very unforgiving, so you must become religious about SAFETY FIRST AND FOREMOST. Sorry about shouting there, but this really is important.

Go to: http://headwize2.powerpill.org/projects/index.htm to find a wonderful site with lots of cool schematics and articles for the DIY'er.

I've built the Morgan Jones amp that's listed at the Headwize site (with slight variations - it's the 'optimised' circuit with a different power supply - and it's the one I'm listening to now!). You can see pics of it and a discussion at: http://www.diyaudio.com/forums/showthread.php?s=&threadid=14035&highlight=pics and http://www.diyaudio.com/forums/showthread.php?s=&threadid=11529&highlight=bang+flash

An even cheaper amp, although not nearly as good sounding (a great 'first' project though) is the little Chu Moy amp, also found at the Headwize site. It uses a pair of OPA134's and can be built for less than $40. The amount of build time varies with skill. IIRC I spent a weekend from dead start to *music* on the last one I built....

Before you do anything, you really should do some reading, start to assemble your tool kit (a good soldering iron and good quality solder are "MUSTS" in my book!), learn your way around the different parts houses, and get organised. It's a fun hobby though, and the feeling you'll get the first time you hear music playing through something you built yourself is always magic....

One word of advice - always have test headphones and/or speakers for your projects for use during the proving trials. There is absolutely no point in risking your good headphones or speakers until you know that the amp works without "issues".

Lastly, If you're going to get really serious about learning how valve amps work, one book you should read is Morgan Jones' "Valve Amplifiers". Another would be any edition of the RCA Receiving Tube Manual (RC 30 was the last one to my knowledge, and it still surfaces with regularity). The RCA manual not only will help you learn your way around the different valves out there, but there is a nice little intro to different circuit types as well as schematics in the back of the book. There are more advanced books out there, like Termans' Radio Engineer's Handbook and The Radiotron Handbook, but they are not for the faint of heart.

PS http://www.tubecad.com/ is a great site too, but many articles are a bit advanced. Still, if you REALLY want to learn how these things work it's a good one - and it's free to visit.

Good luck and all the best,
Morse
 
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