My goal at Little Ruthie Amps is to work together with you to design an amp that is uniquely yours. Your “Signature Amp”, custom built just for you. No one else will own an amp like yours.
People build custom race cars, hot rods, motorcycles, or custom homes. The idea is always the same, what you want is what you get.
So how do we work together to figure out what kind of amp you want? I don’t make “Off-The-Shelf” amp models. I won’t say, “The Little Ruthie model XYZ-2098-DSP is the amp for you.” That’s not custom. Like eating in a cafeteria or buffet, you take some of this, some of that, and pour a lot of the other stuff over it. There it is, your custom meal, just the way you like it. Here’s how the buffet line works at Little Ruthie Amps:
PREAMP – Your guitar plugs into a preamp. The purpose of the preamp is to amplify (to increase the voltage of) the guitar, “instrument level,” to the voltage necessary to drive the power sections of the amplifier, “line level.” My preamp design is quiet, has high input impedance and a lot of gain (“Gain” is a measurement of how much amplification an amp has). This preamp works well with effects pedals or you can get a great sound by plugging the guitar straight in.
Gain – We just defined gain above. After the preamp we start to add one or more stages of gain. This is how we control the distortion characteristics of your amp. More gain requires more tubes. I tell customers to choose one of these four (4) gain designs:
- Clean- good for Traditional Country, Jazz, Funk, or a good setup if you want the amp to stay clean and you use pedals to get your different tones.
- Crunch- stays clean, but when you turn it up and/or pick a little harder it starts to break up. Useful for a lot of different playing styles.
- Overdrive- the sound of Classic Rock, Grunge, Punk, etc.
- High Gain - great for lead work. Makes the guitar "sing" with sustain. Metal players use this sound for riffs and power cords. If you play low chords with this much gain the amp could sound "Flabby". Try turning done the Bass control a little.
Tone Stack – My amps have two tone controls, Treble and Bass. This design is simple and works fantastic. If you want Mid or Presence, I can add them. There are two different types of tone stacks available: American (Fender) or British (Marshall). The main difference between these two designs is where the tone circuit is placed - before or after the gain stages. The American circuit puts the tone controls before the gain stages. So, if you want more distortion and drive with the higher notes simply turn up the treble. The British tone controls come after the gain stages. This means the tone stack is used to shape the harmonics that are added to the guitar by the gain stages. There are a few other differences, but this is the main thing to think about: If you keep the amp clean, go American. If you play with a large amount of distortion, British is better.
Phase Inverter – The phase inverter connects everything we have talked about so far to the Power Amp. You have three different circuits to choose from:
- Cathodyne- This circuit is lower gain, in fact, it adds no gain to the overall amp. So, the amp tends to stay cleaner sounding. When you do push it, the cathodyne circuit provides a nice warm subtle overdriven sound.
- Long-Tail Pair- This is the high gain choice of the three. The long-tail pair is much more popular these days, it seems. The added gain from this circuit means you can drive the Power amp into distortion, with a very nice tone.
- Transformer – Adds more harmonic content than the traditional tube designs.
Power Amp – Now that we have all this great tone going for you let's give it some power so we can move a bunch of air:
- How much power is enough? I have two offerings for you. Medium (10-20 watts) or Large (30-50 watts). I have built a lot of 15 and 20 watt amps for guitarist playing in clubs and dance halls. If you use a good efficient loudspeaker you will be amazed at how loud they can get. The whole idea is to keep the stage volume low and let the sound system and sound tech control the mix. Put a mic in front of a 20 watt amp and you can cover any size gig. That said, some of us have a need for earth moving, ball busting sound. 50 watts with a good loudspeaker setup will do the job for you.
- What kind of tube to use? Medium sized amps will use 6V6 or EL84 tubes, for American or British sounds respectively. Large amps will use 6L6 or EL34 tubes. Same difference, American vs. British tone.
- Negative feedback takes some of the signal from the output of the amp and feeds it back into the phase inverter. The idea here is to cancel out any differences (distortion) between the input and the output of the amplifier. Fender uses a fair amount of negative feedback. That has a lot to do with why the old Fender amps sound clean and tight. Marshall uses less negative feedback. That makes an amp like the JCM 800 give up a nice distorted sound that plays a little looser. Taken to an extreme, VOX uses no negative feedback at all in amps like the AC-30, making for loads of distortion and an almost "out of control" feel when cranked up.
- Class and bias. These are the two terms everyone uses to decide if an amp is hip or not. You can read my comments on the FAQ page of this website. My amps all use fixed bias in a class AB configuration. I adjust the bias so the tubes run "hot", somewhere between 90 - 100% of the tube's maximum plate power dissipation spec.
Power Supply – This is the part of the amp that provides power to all the other parts of the amp. You have two types to choose from here:
- Tube Rectifier - All of the early amps (before 1960ish) used a tube to convert the AC coming in to the amp to DC, the kind of voltage the tubes need to run on. Tube rectifiers exhibited a trait called "Sag". This means the DC voltage drops a little bit when you play at a fairly loud volume, creating a compressed effect naturally.
- Solid State Rectifier - Now we use diodes to rectify the AC coming into the amp. This keeps the sound tight, especially when playing chords. I'll build an amp with a tube rectifier if you would like, but the cost is quit a bit higher and I really think a solid state rectifier makes for an overall better sounding amp.
Loudspeaker – No other single component will affect your tone more than the loudspeaker. This is where I will encourage you to spend some money. I use speakers from Celestion, Tone Tubby, and Jensen. You can pick from Ceramic, Alnico, and Neodymium magnets, too. I hope to get a series of sound clips up here in a few weeks so you can hear the difference between them.
And that's not all! I can add effect loops, line outs, etc. Just ask. We have a lot of cosmetic choices available as well. Please contact us if you have any questions.
Special thanks to Tom Day for his expert help editing this page. Tom, you rock as a technical editor and I am privileged to have known you for so long.