Post by wannaplayblues on Jan 23, 2020 6:26:33 GMT -6
Done LOTS of reading recently about amplifiers and some little tricks to use with them; and seeing as we don't have a thread dedicated to amplifiers and that all elusive tone it can create, I decided to create one.
I'll add tips and tricks as I find them - feel free to add your own.
Also, if you add a tip, make the first line CAPS and BOLD as a title to what it covers, my first entry should be an example...
I've added humour where possible and stayed light-hearted to keep it a fun and entertaining read
Post by wannaplayblues on Jan 23, 2020 7:00:51 GMT -6
INSIDE YOUR AMPLIFIER - THE VARIOUS STAGES
This is a quick and simplified explanation to the amplifier and how it basically works. Regardless of it being a combo-amplifier (the head and speaker built in one case), or just the "head" (where a speaker cabinet is attached externally via cable) the basic workings are the same. Here's a rundown of the signal processing stages:
Input This is where you plug your guitar cable in and how the pickups transfer the signal into the amp's chain
Preamp This is the first stage and usually characterises the amp (in connection to a specific speaker type/setup). It's what makes your tone via the amp model's unique sound. This can be made up of (usually) 2 channels, "clean" and "overdriven" to "color" the signal to your taste - they may have their own channel equaliser (eg. bass/mid/treb) controls too! The overdrive/drive channel can be thought of as a simple overdrive pedal - used to saturate the tone at this stage. Tube amplifiers: The first tube that your guitar pickups’ signal will get to is the first preamp tube. In many amps, it’s a 12AX7. If you're gonna walk up to an amp and plug in with no pedals - this is the stage that makes the signature tone!
Effects Send/Return (optional) Some amplifiers include a Send/Return. This is where the (now preamp styled/colored) tone is sent to effects pedals for processing before a return for the final stage. The advantage of this send/return is that the effects pedals work are not impacted by the preamp. Basically, if you run Guitar -> effects pedals -> Input(above) then the effects are colored by the preamp drive/equalisation etc (this could be what you want) however, the send/return ensures your pedals happen after the coloring/equalisation.
Built-in Effects (optional) This is where reverb and all other effects included with your amplifier are added in.
Power Amp This is where the overall volume control comes in. The final signal is then output at a much larger version with voltage high enough to drive a speaker. Remember, in the words of Nigel Tufnel, "11 is one louder!" Tube amplifiers : Just as the guitar signal is amplified by the preamp tube, the signal from the preamp tube is amplified by the power tube.
Speaker This is where the final sound comes out. A combo has the speaker built into the box housing the head - an all-in-one. A "head" on its own can only process the signal and requires an external speaker cabinet (1x12/2x12/4x12 etc). They're rated by diameter size in inches and the number of them, so a "1x8" is "One 8 inch speaker" whereas a "4x12" is "4 lots of 12 inch speakers" (Think Marshall Stack and Guns 'n' Roses ). Typical inch sizes are 8, 10 and 12. It's important to note however, several things still impact the way the tone sounds at this point
The type of speaker - it's size and dynamic capability being important factors. Just look up a celestion speaker and see how they describe it (eg celestion.com/product/26/heritage_series_g1265/ saying "With its fast attack and tightly controlled low end...")
The case housing the speaker (be it combo or just the cabinet) affects the final product. A closed-back cabinet will sound with more bass to the tone.
They're rated in WATTs as a power output - generally speaking, more WATTs equals more volume. I'm no pro on this, but basically, your 10watt home practice amp wont fair well at a gig night Sufice it to say, there are many Internet discussions about how many watts you need for various stage sizes. They all seem to be opinions
Because voltage is applied, the Ohms of the speaker become important. If you have too much resistance from the speaker, you blow the Power Amp. Too little resistance and you blow the speaker. Gotta get the balance right especially if connecting to external speaker cabinets. Speaker cabinets will indicate their resistance in Ohms, and the "head" will indicate it's minimum or required amount at the connection jack on the back. Some combo amps have the speaker connect via a cable, essentially allowing you to plug the "head" portion of the combo into an external speaker if desired.
That's it in a nutshell... or a wooden box with pretty fabric designs and logos on the front
Post by wannaplayblues on Jan 23, 2020 10:11:17 GMT -6
FINDING YOUR AMP'S SWEET SPOT
To get the best out of your amp, you need to find its sweet spot - where it's most responsive. You tweak the bass/mid/treb dials in the correct way to find it. Each amp is different and the environment/room can impact these settings, so if you move the amp, you may want to check them again. Basically, you're trying to find your specific amp's best tone.
One-by-one you roll off the eq control (say, for the bass) and keep playing something simple while rolling the eq back on until you HEAR the effect come in and make the most difference at a specific (sweet) spot on the dial. Do this for all three for the best results. Then alter to taste, perhaps scoop-the-mids (which means dial them out) or turn up the trebble for a brighter sound, etc. It's up to you at this point!
Yeah, I know that's complicated to read and understand... so grab a drink and watch this video on it...
Blues Jr. for best sound run master volume at 10 use the volume to adjust tube break up. For home use you need a variac to put between speaker and amp so you can control output volume. This tip works for most tube amps as tubes sound better when they are running hot.