#1
So, I was reading about all these great vintage Silvertone amps, and I figured, why don't I build one?

So I got onto Google and found every Silvertone schematic I could. I went onto Harmony Central, and read all the descriptions of all of 'em. I realized I liked Silvertone amps in general, and wondered if I couldn't just make my own custom amp using all the bits I liked and parts of the schematics.

And then, I realized that I don't know jack squat about building electronics, especially tube amps.

So, before I start drawing my own schematics and such, here are some n00b questions I'd like to have answered...

1. In a nutshell, how does a tube amp work?

2. How do you build a simple two channeled amp, and how can you configure one channel to be clean/overdriven and the other to be distortion?

2. How do you build a spring reverb?

3. How can I adjust any given wattage amp to be around 50w? Do speakers, caps, and pots affect this?

4. Is gain control part of the distortion circuit?

5. If I want to design it so that there's a head and a cab, how do I do that?

6. EQ?

7. What do caps, pots, speakers, etc have to do with shaping the sound?

If there's anything else I should know, please tell.

Thanks all.

WHAT HAVE YOU DONE
#2
Oh wow. . .
Gibson SG Standard
Fender 52 RI Telecaster
'77 Deluxe Reverb
Sunface w/ SunDial
MXR Carbon Copy
Crybaby



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#3
Your best bet is to buy a book for all of these questions tube amp building can be VERY complicated as well as dangerous. (I've gotten blown over while trying to mod an old Marshall Plexi)
Gear:
1980 Gibson SG Standard Cherry Red
Ibanez TM-71 Talman Artcore Semi-Hollow
2003 Tom Delonge Fender Strat Seafoam Green
Traynor YCV40
#4
WTF, I'll see if I can help you out. But first, most tube amps use high voltages, which can be lethal. You must understand that you risk death if you don't know what you're doing... seriously. You can play with tube amplification at low voltages, however: http://www.thomasdog.com/amps/sopht/

#1 In a nutshell, ALL amplifiers work in the same manner. They use electronic components in circuits who's relatively high voltages and currents are controlled by relatively low voltages and currents. Think of turning a faucet/tap, and comparing that to stopping the flow of a hose with your thumb It's the same general idea, except that instead of the pressure and flow of water, you're controlling the pressure and flow of electrons.

#2 Two-channel amps have inputs that connect to different parts of the amplifier circuit. Most valve(tube) amps have at least one preamp tube and one output tube. The preamp tube's job is to take the tiny signal from your guitar, and make it bigger. It makes it bigger by a multiplier factor. This factor is known as gain. So, if the preamp tube amplifies the signal coming in 20 times, the gain is 20.
The output tube's job is to take the amplified signal from the preamp, and drive a speaker with it. Most tube amps use an output transformer between the output tube and the speaker. The reason for this is because the output tube uses a high voltage and wants a load that has a high resistance(opposition of current). Speakers are best driven with a high-current, low voltage source.
Anyway, in multiple channel amps, the low gain input is connected to maybe only one or two preamp tubes, so the signal doesn't get amplified much before it goes to the output section. Another channel is connected to more tubes that amplify the signal quite a bit more, and induce a term known as overdrive. Simply, when a tube is overdriven, it squashes the peaks of the wave form going through it, which is how we achieve that awesome overdrive sound.

Edit: I missed the spring reverb part. Reverb tanks are made of loose springs, where each end is attached to a transformer-like object called a transducer. A section of the amplifier drives the "drive" transducer of the reverb tank, and another part of the circuit feeds the signal that comes off the other transducer to which the opposite ends of the springs are connected. The signal is then fed back into the "dry" original signal. The depth and amount of reverb are controlled by controlling the gain of the driving amp and return amp.

#3 The specified wattage of an amp is usually the rated amount of power that the output section can provide continuously to drive a speaker(s). This is determined by tube type, configuration, and voltage, transformer type, configuration, and voltage, and a potentially complicated mixture of various ways of connecting components. Basically, anything from less than 1 watt to over 1000 watts is feasible. It all depends on what you want to do.

#4 Usually yes. The "gain" pot on amps directly controls the amount of signal passed on to the following section, and/or the amplification factor of the section(s) it is connected to.

#5 The only difference between a combo amp and a stack is that a combo has the amp circuit built into the speaker cabinet, and with a stack, you have a separate cabinet for the amp, and a separate one for the speaker(s).

#6 Equalization is usually determined by different combinations of resistor-capacitor networks. In series with a signal, a capacitor tends to only pass AC. Since your signal is mostly alternating current, depending on the value, a capacitor will tend to pass higher frequencies, or be a "bass cut." Connected between signal and ground, since caps conduct higher frequencies more readily, this configuration would tend to cut the higher frequencies, conducting them to ground before they make it to the next section. EQs use a combination of capacitors, resistors, and sometimes inductors to filter frequencies in a controlled manner.

#7 Electronic components have everything to do with shaping the sound. It is the physics of how the flow of electrical energy is literally affected by different configurations of conductors, insulators, and semiconductors; all of which, in different configurations, produce the electronic components we use today. Sorry, but there really is no simple answer regarding electrical theory. It's no wonder education is required to understand it.

You should know, however, that pretty much anyone can build a great amp, if they have help. If you do a google search for tube amp kits, you'll find a bunch of sites that can get you started. Without knowing a good deal about electronics, building an amp from scratch is going to be fairly ludicrous.
Last edited by Losenger at Nov 19, 2007,
#5
I have the 50 watt silvertone twin twelve. It is an incredible amp (blows away a lot of fenders imo). Plus It still has completely original tubes from 1967. I think it'd be more worth your while to just find one for sale, you can still get one relatively cheap. If it's all original, the price of it is skyrocketing. I've always thought it would be a great idea to make a "new" one of it, with a more sturdy construction.
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#6
1. In a nutshell, how does a tube amp work?

Go here: FUN WITH TUBES The best tutorial about tubes on the net (imho)
Read the sections on Audio.

2. How do you build a simple two channeled amp, and how can you configure one channel to be clean/overdriven and the other to be distortion?


More stages of gain (more tubes)

2. How do you build a spring reverb?

You don't. You could, but it just wouldn't be worth the time and effort. Buy a replacement reverb tank from Accutronics or some other manufacturer.

3. How can I adjust any given wattage amp to be around 50w? Do speakers, caps, and pots affect this?

You can scale the power down, by altering the voltage in the power supply. Increasing the power supply voltage in an existing amplifier will likely cause catastrophic failure.

4. Is gain control part of the distortion circuit?

A gain control is like a volume control, early in the circuit. If you turn it down so the signal is small, it won't be large enough to distort.

5. If I want to design it so that there's a head and a cab, how do I do that?

Put the amplifier chassis in one box, the speakers in another. Connect the two together with a cable.

6. EQ?

Tone controls. Learn about FMV tonestacks, Bandaxall controls, and others here: TSC

7. What do caps, pots, speakers, etc have to do with shaping the sound?

Once you've read all the material in the links I provided, you'll know about caps and pots. Speakers change the electrical energy into sound. All the speakers you would use for a guitar amp work the same way, just like cars all serve the same function. But just like cars, they all drive and handle differently. It's far to complicated to say much more than that.

If there's anything else I should know, please tell.

The voltages present in a tube amp are capable of KILLING you. Use proper caution, and learn how to safely discharge the capacitors before putting your hand inside the guts of a tube amp.

Good luck,
SYK
Meadows
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#7
I would love nothing more than to have a kit to stick together, but budget's really tight, so I'm going to read all I can about building amps, wing it, and hope for the best.

Thanks for all the help.
My dad's an electrical engineer, so I'll try to pull him into this project.

If this ever gets off the ground, I'll post pics and ask advice, etc.

WHAT HAVE YOU DONE
#8
there's a silvertone forum with the exact schematics of every silvertone product ever made. If your dad's an electrical engineer I'm sure he could figure them out for you.
Quote by Sir-Shoelace
manliest string guage? barbed wire.

Founder Of the UG Slide Player's Guild, PM me If You're Really Feelin' Dem Blues

THE PIT
"better than your average psychiatrist"