Current Product Manuals (.pdf)

Discontinued Product Manuals (.pdf)

What is Tone?

Tone is that subjective, magical, mystical, ear-pleasing quality of music that defies definition. We know it when we hear it but we can’t describe it. Usually, it goes something like this: I want that tone that Stevie Ray, or Eddie Van Halen, etc., etc. has on song XYZ. Will your amp make me sound like…? The short answer is: No. The long answer is: Maybe. There is no right or wrong answer to this question. The tone you get from a system starts with your hands, goes through your guitar, through the amplifier, through the air, and back to your ears. The tone you get from a system is the sum of the parts. If it pleases your ears it is good tone. If it really pleases your ears it’s fabulous tone.

I play ABC genre/style of music. Will your amp Model X allow me to cover that style? The short answer is: Probably. The long answer is: The question is too broad with too many variables. Our combo amps, like the Lindy Fralin and Blue Bel Aire, will cover most styles of music from Jazz to Blues to Rock and Roll. We believe that our head amps like the Rick Derringer or Earthquake models will cover almost any style or genre of music. Again, the tone you get from a system is the sum of the parts. How do you play? Do you pick the strings hard? Are your pickups hot? Will they drive the amp to early distortion? You have to answer these questions yourself and decide what will suit your style.

Are your amps wired point-to-point or do you use PC boards?

Building guitar amps by hand in the good ol’ USA is expensive and we have a lot of very good competition. Our mission has always been to build the best amps possible and make them affordable. So, we use point-to-point wiring, hand made eyelet boards, turret boards, PC boards, and any other method we can think of the achieve our goal. Many of our peers would say we’re sacrilegious but we’ve built hundreds of amps and repaired thousands of guitar amps since 1969. Based on our experience, there is no tone magic in point-to-point wiring, eyelet boards, or any of the other bunk that the “experts” get so worked up about.

There is, however, real magic in the choice of parts and component placement/layout. Are we saying that a PC board amp can sound as good as an amp wired point-to-point? To this question we can emphatically say: Yes! Moreover, we get much better consistency from PC boards over our short production runs than we do from amps wired point-to-point. That being said, there is a down side to PC boards; they are not easy to modify or tweak. The design is etched in copper so to speak. Other than that, there is no down side if it’s well designed. And, we have seen many poorly designed PC boards with power sources in parallel with signal paths and high density component layouts that induce noise and capacitance topped off with cheap components that sucks the tone out of a well conceived design. Usually, these are high production amps with very familiar names but not always. We’ve seen the same problems in “boutique” amps. At VVT we build our prototypes with a combination of point-to-point wiring and hand made eyelet boards on FR4/G10 phenolic. After we are satisfied with our choice of components and overall layout we tweak and voice the amp to perfection. Then, we make a short run of 5-10 amps and test them for consistency. If all goes well, we design a PC board with attributes and layout as close to the hand made eyelet board as possible. We mount our choice of components by hand, solder them by hand, and build the amps by hand. If having a PC board in your amp bothers you please let us know. We will build any amp your heart desires point-to-point but it will cost more than our amps made with a PC board.

What circuit is your amp based on?

This is a very hard question for us to answer. After repairing and playing so many amps and looking at the schematics over many years, they all begin to look alike. We have not seen any new designs in tube guitar amplifiers since the early-sixties. Even then, the designers borrowed pieces and parts from others. If a contemporary amp builder has a design that was new and different then he would have a patent. We’ve researched patents and there aren’t any of significance. We have not seen any contemporary tube type guitar amps that were truly engineered from the ground up. However, there are certain tone qualities of some amps that really stand out. We use this to our advantage and take the best pieces of those amps and build them into our amps. We don’t reverse engineer any particular amp and try to mimic that tone. We don’t have the holy grail of vintage amps that we used to measure component drift and other such nonsense. There are many other amp builders that make clones and they do it very well. We just start with an idea for the tone we want and go from there. Let’s say we really like the tone of old plexi amps but don’t like how they respond to pick attack at lower volumes or how they respond to different pickups, etc., etc. We start thinking about how we can make it better and more versatile. To do this we need transformers with a specific voltage or such and such impedance, and components with certain tonal attributes. So, we order the parts and build a prototype. Sometimes, things work out very well. Other times, as in the case of our Overdrive amps, we tweak for years before we offer the amp for sale. If you want a clone of a particular amp please let us know; we will build it for you. But, clones are not part of our standard amp line. For example, the Lindy Fralin Model has many of the fine tone qualities of some vintage BF and Tweed amps but it is not based on any particular amp design.

Want More Headroom?

How can I get more headroom out of my amp?
We get this question all the time and there are several answers depending on your definition of “clean” or “headroom”. Headroom, in this case, is the capacity of your amplifier to reproduce audio signals from your pickups before distortion. Tube type guitar amplifiers are not High Fidelity equipment; they all have a point where they will start to distort (breakup). If you want clean tone, i.e. limited distortion, from your amplifier at higher volume levels there are several things to consider:

1. Pickups. If the output of your guitar pickup is hot, it will drive the amp harder at the front end and may cause the preamp to distort at lower volume. Try turning down the volume on your guitar. We all know that a typical humbucker pickup has more output signal than a typical single coil pickup. You may or may not be surprised at the myriad of tones and the headroom available by controlling the volume knob on your guitar.

2. Preamp Tubes. According to the RCA Tube manual, a 12AX7 high mu dual triode has an amplification factor of 100. However, this factor can vary greatly from manufacturer to manufacturer. We know from testing several NOS RCA 12AX7s that some exhibit higher gain than others in a given circuit. Additionally, gain, or amplification, can vary greatly within the two triodes of the tube. The same is true for newly manufactured tubes from Europe, Russia, and China. So, try several different preamp tubes in your amp to improve headroom. You can also try a tube like the 12AY7 with an amplification factor of 70.

3. Phase Inverter Tube. The PI is usually overlooked when it comes to headroom. Try different tubes here as well. If your amp has a 12AX7 in the PI try replacing it with a 12AY7 or 12AT7/ECC81.

4. Output Tubes. There is a lot of misinformation related to this topic, but matched output tubes are critical to clean headroom. Unmatched tubes will definitely affect crossover distortion and apparent headroom. The downside is that the tubes will age at different rates and will become unmatched in a fairly short time. Don’t expend too much effort here but matched tubes are always a good starting point. Also, as with preamp tubes, output tubes from different manufacturers will have more inherent headroom (and different tone qualities) than others. It’s always a trade-off.

5. Speakers. Speakers play a crucial role in the amount of headroom the amp exhibits, so before you say my amp needs more headroom it could be your speakers. As speakers begin to break up, they also begin to compress, causing a change in the frequency response. This becomes very noticeable in the lower notes as they lose focus and start to produce a gritty type of grind. If this is the case you may need to increase the power handling capability of your speakers. A good place to start is by doubling the speaker’s power rating from that of your amps power section. If your amp is rated at 50 watts, your speaker or speakers should be rated around 100 watts. Keep in mind this is a starting point. If you like a little speaker breakup try a 75 or 80 watt configuration. If you want no breakup, go to a 150 watt setup. There are no set rules here. Stevie Ray Vaughan liked a 200 watt EVL in his Vibroverbs (50 watt amp), virtually no speaker breakup. Speaker choice is a very personal issue and has a great impact on tone and headroom. Both the Fralin and Blue Bel-Aire’s speakers have been designed for small (100-150 seat), halls or restaurant type gigs and still stay relatively clean. This makes them pedal friendly as well as a great platform for many styles of music.

Should I get a 100 watt amp or a 50 watt amp?

Despite what you have read or what you might think, 100 watt tube amps will not produce twice the volume of a 50 watt tube amp. The difference in volume is about 3db which is barely audible. Where you will hear the difference is in the TONE of the amp. 100 watt amps will seem louder due to the increased bandwidth propagated by the extra output tubes, this decreases the load on the tubes themselves so you don’t get the anomalies associated with a tube about to clip. This gives the amp more headroom, increased low end, better touch sensitivity, and a clearer cleaner top end, in effect making the amp seem louder since you are hearing a clearer richer sound produced by 4 tubes instead of 2. 100 watt amps are not that much more expensive than a 50 watt amp. Slightly larger transformers and 2 more output tubes (as well as the capability of turning off 2 of the tubes essentially converting the amp back to 50 watts) gives you an amp that will go from a small club amp to an outdoor arena style amp.

So remember if someone says 100 watts don’t think volume think TONE!! All of our 100 watt amps come with a volume control no extra charge. ?

What is Cathodebias (aka) Auto Bias versus fixed bias?

Cathode bias is an early method of biasing tubes where a resistor is placed in the cathode. Current draw through this resistor makes the grid potential negative with respect to the cathode. And, changes in tube conduction are automatically compensated by changes in bias so it’s also referred to Auto Bias. In Fixed Bias a negative voltage is applied directly to the grids of the output tubes. It should be noted that preamp tube are almost always cathode biased whereas output tubes may be either or both. Without getting into the technical issues of the difference between a fixed bias/cathode bias we will talk about the tonal qualities and how they differ in the real world.

The Pros and Cons.

Fixed Biased:
Fixed biased amps are more efficient, it is a brighter, tighter, punchier tone and needs to be pushed louder to find a warm sweet spot. Fixed bias also increases the headroom of the output section keeping the amp cleaner as it gets louder, yet the transition into grind is bit edgier. This design also requires you to bias the amp when replacing output tubes.
On the whole, most amps are fixed bias, your Blackface Fenders, Marshalls, and many of the newer amps such as Boogies etc.

Cathode biased:
Cathode biased amps have a slightly browner tone giving them a real warm appeal.
They also seem to have a rounder more full tone at lower volumes, and transition into grind smoother than a fixed biased amp. They also begin to compress sooner and have a more round, less focused low end, as well as a sweeter compressed, less edgy top end. They also have slightly less headroom.

Cathode biased amps don’t need to be re-biased when installing a fresh set of output tubes (but the set still needs to be matched). It is also a good idea to try and replace the output tubes with the same current draw as the originals. Most manufactures of tubes use a numbering system or color code to identify the tube’s draw. This keeps the tubes at the proper operating point.

Cathode biased amps include, Vox AC 30’s, older Fender Tweed amps such as the Pro, Tweed Deluxe etc.

The description above explains the differences in tone in the same amp with a fixed bias/ cathode biased conversion. This is not to say a cathode biased Vox AC 30 won’t have as much headroom if not more than a fender tweed Deluxe, the intention is to describe the tonal differences you will notice in either design.

We designed the Fralin Model around the appeal of the cathode biased design yet give the amp more clean headroom than the earlier Tweed Fenders.

Are your amps Class A?

This question always opens a can of worms but the answer is: No. All of our amps operate in Class AB except our single-ended amps which operate in Class A. The amp class debate is, and will continue to be, like herding cats. There is some good information and much disinformation on this subject available on the web. You decide which one is best for you based on a listening test. It should be known, however, that just because an amp is cathode biased doesn’t mean that it’s operating in Class A. That’s just a marketing scam.