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Stupid questions..

J. Crawford

J. Crawford

Feb 15, 2008
14,147
2,877
FL
#1
Okay guys. I have been embarassed to ask this, but I need to know some terms you guys use and have no clue, or little, about what they mean.

pots?
Is there an internal preamp and external preamp? Whats the difference?
What does copper foiling do?

Those are really it.. I feel dumb, but I need to know. :(
 
#2
Pots are short for "potentiometer" (the device used for volume and tone controls).

A preamp is a circuit that typically involves 2-4 controls (or more on an amp) for altering the tone of the signal. Preamps can be found in a variety of configurations including: internal (inside the bass body), pedal format, rack-mount format, or as part of an amplifier.

Copper foil is commonly used as shielding inside an instrument's control cavity to help reduce outside electrical interference that can cause noise (hum).
 
#3
I'm no expert but I have a couple of answers:

Pot = Potentiometer. What the volume and tone knobs on your bass are attached to.

Pre-amps. Some active basses have internal pre-amps. Passive basses do not. All power amps need some sort of pre-amp. A lot of standard amp heads and combo amps have the pre-amp and power amp in the same enclosure.

Not sure on copper foiling, but I think it has something to do with shielding to prevent electro-magnetic interference with your pickup signal.
 
#12
Gotta a few more for you guys.

1. What is an ohm? What does that mean?

2. What is a "tube amp", and why must they warm up?

3. A head just connects directly into a cab, and is turned on when the head is turned on? Any random details on this would be great.

4. What is the difference in a 1x15, 2x12, etc. except amount of sound? When making a rig, why have a 1x15 and a 2 or 4x12?

I know these are dumb questions, but I want to not be so ignorant on these subjects.
 
#14
Jordasch said:
Gotta a few more for you guys.

1. What is an ohm? What does that mean?

2. What is a "tube amp", and why must they warm up?

3. A head just connects directly into a cab, and is turned on when the head is turned on? Any random details on this would be great.

4. What is the difference in a 1x15, 2x12, etc. except amount of sound? When making a rig, why have a 1x15 and a 2 or 4x12?

I know these are dumb questions, but I want to not be so ignorant on these subjects.
Click to expand...

I'll take a swing at it...

1. An ohm is a unit of electrical resistance (for direct current) or impedance (for alternating current, i.e. audio signals). It's named for Georg Ohm of Ohm's Law fame.

2. A tube amp is an amplifier that uses vacuum tubes as their active components. Each tube has several elements inside of it one of which is a "heater" that has to warm up before a tube will function.

3. The speaker in the cabinet is just the output device (called a transducer) that converts the signal from the amp into sound by moving the cone of the speaker. The speaker doesn't need to be "turned on" per se just hooked up to the appropriate output of the amplifier.

4. Different size speakers sound different. The selection of what to use is personal preference.
 
#15
First, and I say this in kindness, any time there is basic info you have questions about, it is almost a guarantee that it's in the FAQ. So always read any FAQ or stickied thread in any forum in which you have basic questions. Any term or question not revealed in the FAQ can usually be resolved by doing a search.

Now that I got that out of the way, here are some answers:

Jordasch said:
1. What is an ohm? What does that mean?
Click to expand...
An ohm is a unit of measure, and it is used for two different types of measurement so you have to be very sure which type is being discussed. One type is "resistance", and that is used for components such as resistors and pots (potentiometers, knob controls, which are variable resistors). The other type is "impedance", and that is used to describe how efficiently one component will transfer power into another component. So for example an amp will have a set of ohm ratings for its output, and a speaker will have a certain ohm rating for its input, and they have to match (read the FAQ for specific details on how to do the math, because it's not always just two numbers to compare). There are also impedance relationships between your bass and your amp, and any other gear that is connected together- pedals, mixers, DI boxes, everything. But at this stage of your playing you don't have to worry about those as much as you do have to be careful about amp/speaker connections. I can't say it enough times- read the FAQ for more info.

Jordasch said:
2. What is a "tube amp", and why must they warm up?
Click to expand...
Tubes are electronic components that resemble light bulbs. These days they are mostly used for amplifying signals. They need to warm up just because that is one of the mechanical limitations of their old-fashioned gas-in-a-glass-container performance. A "tube amp" is one that uses tubes for all of its amplification stages. Very often you'll see tube preamps or "hybrid amps" which are amps that just have a tube or two in the preamp stage. Those do not need to warm up necessarily, because preamp tubes don't have to handle as much power as some others.

Jordasch said:
3. A head just connects directly into a cab, and is turned on when the head is turned on? Any random details on this would be great.
Click to expand...

Not sure what you're asking here. A speaker cab generally does not have any power of its own (there are exceptions) so it does not need to be turned on. It just sits there passively waiting for some power to be sent into it by an amplifier. The exception is what's called a "powered cabinet" which is one where there is an amplifier built into the same box as the speakers- but even there, it's not the speakers or the speaker cab that you switch on and off, it's the amplifier module that just happens to be jammed in there too.

Jordasch said:
4. What is the difference in a 1x15, 2x12, etc. except amount of sound? When making a rig, why have a 1x15 and a 2 or 4x12?
Click to expand...

Subjective and variable. This is the sort of thing that is not smart for anyone to generalize about; your best bet is to just try out a range of different speaker combinations and see what sounds good to you. Don't believe anyone who tries to tell you "tens sound like this and fifteens sound like that".

Did I mention reading the FAQ?
 
#16
mongo2 said:
I'll take a swing at it...

1. An ohm is a unit of electrical resistance (for direct current) or impedance (for alternating current, i.e. audio signals). It's named for Georg Ohm of Ohm's Law fame.

2. A tube amp is an amplifier that uses vacuum tubes as their active components. Each tube has several elements inside of it one of which is a "heater" that has to warm up before a tube will function.

3. The speaker in the cabinet is just the output device (called a transducer) that converts the signal from the amp into sound by moving the cone of the speaker. The speaker doesn't need to be "turned on" per se just hooked up to the appropriate output of the amplifier.

4. Different size speakers sound different. The selection of what to use is personal preference.
Click to expand...

Thank you! Okay.

1. What does an ohm do? I hear about 4 and 8, but have no idea. I am looking into a new rig, but do not understand this

2. What is the difference between this and a normal head?

3. So, a head is the main source of the cabinet? The head does not make any noise, just controls the cab?

4. Good enough.

Someone move this to Amps section for me?
 
#17
Jordasch said:
1. What is an ohm? What does that mean?
Click to expand...

An ohm is a measure of resistance. It can get pretty complicated, but here is the short version. Every speaker you connect to an amp demands more power from the amplifier. The amplifier, at least in solid-state examples, is designed to give more power but they can only give so much. If you connect 2 4-ohm cabinets to an amp that can't give more than 4 ohms, it will overheat. You will experience thermal shutdown and may cause permanent damage to the amp.

Understanding that, here is your formula. 2 8-ohm cabs will draw 4 ohms from your amp. 2 4-ohm cabs will draw 2 ohms from your amp. Every amp that I know of goes down to 4 ohms, but most do NOT go down to 2 ohms. Know your amp's minimum ohmage and do not try to draw more power from your amp than it can handle and everything will be peachy. You can learn more about this if you want, but that should be all you need to know to get by.

Jordasch said:
2. What is a "tube amp", and why must they warm up?
Click to expand...

Tube amps use tubes for their power supply instead of solid-state transistors. Not sure why they need to warm up. I just always followed directions in that regard (i.e. let it warm up).

Jordasch said:
3. A head just connects directly into a cab, and is turned on when the head is turned on? Any random details on this would be great.
Click to expand...

Cabs do not turn on, they don't have on/off switches. They simply react to the fact that power, from your amplifier, is being sent to them and do what they are designed to do. Just make sure that all connections (bass to amp, amp to speakers) are made before turning your amp on. That way, you avoid the loud pop that happens when plug something in after you've turned on your amp. This can wreck your speakers rather quickly.

Jordasch said:
4. What is the difference in a 1x15, 2x12, etc. except amount of sound? When making a rig, why have a 1x15 and a 2 or 4x12?
Click to expand...

The only difference is amount and type of sound. This is a highly subjective area. Some like 10s, some like 15s, others like 12s. Some like a combination of 2 or more of each (i.e. a 2x10 and a 1x15) to get the best attributes of each kind of speaker. 15s are typically deeper-sounding, they push a lot of air, but can be muddy and indistinct. 10s are fast and give you lots of "punch", but sometimes they don't handle lows very well, especially on a 5-string or downtuned 4-string. 12's are kind of in between 15s and 10s, they are deeper than 10s, but punchier than 15s. Then again, they are not as deep as 15s or as punchy as 10s. Its all about your personal preference. I like 12s most, but also like 10s quite a bit. I don't care much for 15s.

Of course, these are generalizations. There are 10s that sound really deep and 15s that are clear as a bell. There are so many different options out there your head will spin if you try to learn them all. You've just got to learn what YOU like and what makes sense for your rig.

Hope this long-winded post helps you.
 

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