Rumble 40 Volume vs Master newbie question

[Photonic]

Embarrassing to ask, but I clearly do not understand the difference between my Ruble 40's Gain knob and the Master knob. Both seem to increase "volume". I never play drive or any of the "tone" buttons activated. So in beginner's terms, can you educate me on how to understand these two controls and how to use them for simple at home music practice room playing. Thanks for bringing up "junior"!

 

[MIMike]

The Master is your “volume” knob, the Gain adjusts the signal the amplifiers pre-amp sees from your bass.

 

[Photonic]

The Master is your “volume” knob, the Gain adjusts the signal the amplifiers pre-amp sees from your bass.

So saying, then how does one know how much gain to apply vs just adjusting the master knob? Told ya I was a newbie!

 

[David Morison]

Typically, you'd start with the Amp's Master Volume nice and low & Overdrive switched off, then turn up your bass's volume to max, then increase Gain on the amp as much as you can without causing any distortion.
That ensures the rest of the signal chain within the amp has a decent healthy level of signal to work with without risking adding too much background noise such as hiss from the circuitry.
If you find you like the tone of the amp with any of the EQ controls boosted, you may need to back off the Gain a little more.

 

[Hoochie Coochie Man]

See page 10 of the Fender Rumble owners manual to find the block diagram which may help you understand where the controls are located in the signal flow:

https://www.fmicassets.com/Damroot/Original/10002/237030_bamp_manual_all_revA.pdf

See page 8 of the manual for the following description of the Gain, and Master controls:

B. GAIN — Adjusts the incoming signal level from your bass, optimizing the preamp signal level for a variety of basses.

The GAIN control will also affect the level of distortion/compression if VINTAGE and/or OVERDRIVE are selected.


H. MASTER — The MASTER controls the overall volume of the amp.

Rumble amps are equipped with Fender's Delta-Comp™ limiter. Setting the MASTER higher or playing more aggressively will result in more compression and sustain.

 

[Photonic]

Thanks for all the posts. I played around with turning up the gain and down the Master and all sorts of combinations and could not hear any discernible differences. But in my 20x20 "ish" studio practice room, if I turn the gain up to 9 o'clock the master has to sit at about 8-9 o'clock or I blow myself out of the room. If I turn the gain up more, I have to roll the Master close to off. Hmmm so not so sure if any of it makes a difference in my situation.

 

[H Nighttrain]

OK Junior, her's a simple understanding... when you pluck a string your finger is the source of the (mechanical) energy that vibrates the string. A metal string vibrating in a magnetic field creates a small electric current in the wires wrapped around the pickup's magnet. That electric current then gets amplified, using additional electricity, a few times.

If you have a passive bass the pickup signal goes to you "amplifier" (amp). On basses with an active pickup, the signal gets amplified a little first, using energy from a battery.

Inegrated bass amps have a pre-amp and a power-amp. The amount of electricity that boosts the signal in the pre-amp is controlled the gain knob. That signal goes to the power amp, where the signal is boosted once more.

At the end of the chain your speaker takes that amplified electric signal into a voice coil around a magnet that drives a speaker cone, turning the signal back to mechanical energy that vibrates air that vibrates ear drums.

Every time you amplify an electric signal you add some noise. So, in general, it's preferable to dial your preamp gain as high as possible (to maximize the signal-to-noise ratio) without going too high (which causes distortion).

The low-level signal coming from your bass is "instrument level", and active basses generally have a hotter signal than passive basses. Most integrated amps have an attenuator of some kind (an active/passive switch) to account for the difference (i.e., to not introduce excess distortion in the pre-amp stage).

That's the basic story, now go play!

 

[JakobT]

This bit about Rumble gain structure should hopefully make things a little clearer:

Post in thread 'Fender Rumble Club'

Jul 27, 2015

Today's Rumble Talk focuses the spotlight on Gain Structure.
We are very fortunate to get this educational information direct from my contact inside Fender Bass Amplification.

Gain structure for amplifiers is a balancing act between what clips first, the preamp or the power amp, and what sounds best depends on the desired tone goal.

For most old school tube amps the MASTER control functions as an attenuator and only reduces the amount of preamp signal sent to the power amp, so the ‘cleanest’ preamp signal is achieved with the MASTER is full up (no...

• Linnin

• 

Feel free to pop in at the Rumble Club for a chat with fellow Rumble owners.

 

[Photonic]

OK Junior, her's a simple understanding... when you pluck a string your finger is the source of the (mechanical) energy that vibrates the string. A metal string vibrating in a magnetic field creates a small electric current in the wires wrapped around the pickup's magnet. That electric current then gets amplified, using additional electricity, a few times.

If you have a passive bass the pickup signal goes to you "amplifier" (amp). On basses with an active pickup, the signal gets amplified a little first, using energy from a battery.

Inegrated bass amps have a pre-amp and a power-amp. The amount of electricity that boosts the signal in the pre-amp is controlled the gain knob. That signal goes to the power amp, where the signal is boosted once more.

At the end of the chain your speaker takes that amplified electric signal into a voice coil around a magnet that drives a speaker cone, turning the signal back to mechanical energy that vibrates air that vibrates ear drums.

Every time you amplify an electric signal you add some noise. So, in general, it's preferable to dial your preamp gain as high as possible (to maximize the signal-to-noise ratio) without going too high (which causes distortion).

The low-level signal coming from your bass is "instrument level", and active basses generally have a hotter signal than passive basses. Most integrated amps have an attenuator of some kind (an active/passive switch) to account for the difference (i.e., to not introduce excess distortion in the pre-amp stage).

That's the basic story, now go play!

Dear Sensei, I love it. Junior is listening. Great explanation. So since I cannot hear any difference on my rumble 40 with different combinations of gain and master volume, I am just gonna choose some random setting that gives me an overall volume level apprpriate for my practice and get on with life. Hazah! Thanks for your great post, signed, Junior.

 

[Photonic]

This bit about Rumble gain structure should hopefully make things a little clearer:

Post in thread 'Fender Rumble Club'

Jul 27, 2015

Today's Rumble Talk focuses the spotlight on Gain Structure.
We are very fortunate to get this educational information direct from my contact inside Fender Bass Amplification.

Gain structure for amplifiers is a balancing act between what clips first, the preamp or the power amp, and what sounds best depends on the desired tone goal.

For most old school tube amps the MASTER control functions as an attenuator and only reduces the amount of preamp signal sent to the power amp, so the ‘cleanest’ preamp signal is achieved with the MASTER is full up (no...

• Linnin

• 

Feel free to pop in at the Rumble Club for a chat with fellow Rumble owners.

Terrific reference. Thanks do much!!!!

 

[JakobT]

Terrific reference. Thanks do much!!!!

Happy to help. There’s plenty of other useful info on the Rumble Club Wiki if you need it, and you can always stop by the Rumble Club and ask questions of its many knowledgeable members. We’d love to see you!