Newbie wants to learn

[odamone]

One of the reasons I bought a kit was to learn about what really goes into an amp. I haven't built the kit yet (apparently Bottlehead doesn't offer next day or next week and possibly not even next month delivery) but I have looked at the instructions. There's not a lot of theory or fundamentals so I'm afraid I won't learn much more than how to solder and follow directions and take readings.

The thing is, if I ever spend real money on an amp, I want to know what I'm paying for and not get taken advantage of. I've heard the phrase single ended triode, but have no idea what it means. Or ultra linear. Or OTL. I know that resistors resist and capacitors have capacity. I'd guess that transformers transform. But what does a tube actually do? And why do some amps have 1 and others 18?

So with all this to learn, would anyone reccommend any reading? I genuinely appreciate any suggestions. Maybe one day I can come back and debate the finer points of transformerless copper core single stranded silver output stage caps. For now, newbie needs to start somewhere...

Thanks

[Grainger49]

Well, it goes like this.  The amplifier or preamplifier modulates the power supply.  That doesn't mean much now.  But one of the first things you put together in just about every Bottlehead kit is the power supply.  It consists of taking the output of one of the transformer windings and running it through either two or four diodes.  That makes really lumpy DC.

Aside AC is alternating current, DC is direct current.  The definition of alternating is just that it is both positive and negative during a cycle.  Direct current is either only positive or only negative.

But the output is really, REALLY lumpy.  It needs smoothing.  The following capacitors and resistor(s) smooth the DC.  It looks more like a steady state voltage (no lumps).

The tubes are single ended triodes or pentodes.  A triode has three leads (tri- part), a pentode has 5 leads (pent- part).  Single ended I'm not going to define because I always botch that up.  Anyway, there is a steady current through the tube from the plate (top?) to the cathode.  This is caused by the DC across the tube and controlled by the resistor between the cathode and the ground reference, where the negative, or common of the power supply is soldered to.

The input goes to the grid (we now have mentioned the three parts of a triode, plate, grid & cathode) and the voltage on the grid controls the current through the tube. 

When you get your kit post back and tell us what kit it is.  If I have the schematic I can point out these elements to you as you build. 

Looking at my Eros manual I see that the sections are named Power Supply PC Board, Plate Load Servo PC Board, Chassis Wiring ... So it does give some idea of what you are working on.  I hope your kit does that as well.

[Bonzo]

Well,
first of all you have to study some physics (the basis of electromagnetism are mandatory), then you can take a look here:
http://www.tubebooks.org/
There are a lot of sites you can download old manuals or books from, and because we're speaking about tube amps (a 100 years old technology) all these manuals can be considered up-to-date  .

If you are interested in SS amp there is A LOT more to learn, but I'm a civil engineer, I think there are more skilled people around here that can answer 

All the best and happy building!

PS: there is also an e-bay seller who sell the whole "Sound Practices" archive, it was a very informative zine published in the '90s

[corndog71]

I learned most of what I know about tubes by reading a lot where ever I could find info.  Recently I bought an old RCA Transmitter Tube Manual from 1962 on Amazon for around $10.  It brought me back to the fundamentals of vacuum tubes.  Back in those days tubes were everywhere in electronics. 

The best part of all of this is the inherent simplicity of tube circuits.  Bottlehead is great for for relatively easy kits to put together.  I would also recommend studying Dynaco amplifiers as they too are relatively simple circuits.  There's a ton of info out there on them and you can put one together for around $400-500.  Those amps come with a warning as they operate with high voltages that can be deadly.  Be very careful.

Take your time.  Learn to solder and practice it.  Get your tools in order.  The ones I use the most are:

• Needle-nose pliers (with crimper/wire cutter built-in is even better)
• Forceps
• Wire stripper
• Nail clippers (for stripping thinner teflon wires)
• Small scissors
• 30 & 40 watt Soldering iron or adjustable soldering iron.  This should have a holder and sponge.
• Good quality solder
  
  
• Desoldering bulb ( I use a piece of 16AWG solid core wire to unclog it)
• Volt meter (I got a used Fluke volt/amp meter.  A good one will measure volts & amps, AC & DC, resistance in Ohms, and continuity.  Others have inductance and capacitance as well.

There may be others I'm forgetting but those are the ones I use the most.

[Grainger49]

There is a thread, sticky, under Tech Tools that describes the tools necessary to assemble a Bottlehead kit and those that are nice.

Corndog covered many but not quite all of those.  And he knows me well enough that he knows I'm not slapping him.

[adamct]

Damn, Grainger! That was harsh!  Corndog was just trying to help out...cut him some slack!

[adamct]

I kid because I love...

 

[2wo]

If you are looking for a real book that you can hold in your hand and bugger up the corners.
This one is a good place to start...John

http://www.tubesandmore.com/products/B-916

I bet there is is a lot of good info in some of the how to books for guitar amps but I have not read any of them.

The WWII Navy course is supposed to be good and can probably be found at "tubebooks.com"

Search around this forum for other books and online info, you are not the first to ask   

[vrgard]

Here's a website with tons of info that should keep you busy for a while: http://tinyurl.com/2ego78w

-Randy

[STURMJ]

I would also like to note, You learned more than you thought you did.

[odamone]

Thanks, everyone. I've got all my tools (thanks to that sticky!). Just waiting on the sex 2.1 kit.

I was looking for a good book. The link to old textbooks looks like a great place to start.

I guess I was hoping for a book written specifically for audiophiles who don't have an electrical engineering background but want to get into DIY. It would be good to understand how and why different amplifier design decisions actually impact sound. But maybe that book lives with unicorns and leprechauns.

[odamone]

I wrote too soon. Randy's link has exactly what I was looking for! No unicorns, but still. Thanks!

[vrgard]

I wrote too soon. Randy's link has exactly what I was looking for! No unicorns, but still. Thanks!

Glad to hear you found it helpful.  Let the learning begin!   

-Randy

[docbob52]

Grainger,  I never seen a better simplified explanation of tube circuitry than this. It was easily understandable and succinct and I have been building mostly tube stuff for 48 years as a ham and audiophile .   I would love to see you expand this even further and cover topics in this manner such as to how components work in :  the c4s, filament regulators, coupling and bypass caps and so on.

You could write a book about this and I think it would sell.


Robert Howard,

Troy, Al.

[Grainger49]

Robert,

I'd like to have the understanding of the C⁴S circuit that I have of the tube and power supply.  I was offered a job as a tech writer when I graduated.  I already had a liberal arts degree but it wasn't satisfying.  I wanted to get into electrical seriously.

Thanks for the compliments.