Limiting on Rumble and Rocket Bass combos.

[T D S]

Hello,

Do Rumble and Rocket Bass combos always have the limiter engaged while you're playing?

Or does it engage only when the amp is being pushed too hard?

Their user manuals seem to imply that limiting is just there to protect the output section.

Thanks,

T D S

 

[agedhorse]

In general, the owner's manual description is pretty accurate.

That said, it's always more complicated than that because in the case of the Rumble V3's, there are 4 separate compressors (or TCA's) that are used for different things like vintage feel, etc. There is one that functions as an output limiter as well. I don't know the details of Ampeg's new RB series.

 

[T D S]

Thanks for the explanation.

Cheers

 

[flshmtrnks]

In general, the owner's manual description is pretty accurate.

That said, it's always more complicated than that because in the case of the Rumble V3's, there are 4 separate compressors (or TCA's) that are used for different things like vintage feel, etc. There is one that functions as an output limiter as well. I don't know the details of Ampeg's new RB series.

What does TCA stand for?

 

[JimmyM]

Hello,

Do Rumble and Rocket Bass combos always have the limiter engaged while you're playing?

Or does it engage only when the amp is being pushed too hard?

Their user manuals seem to imply that limiting is just there to protect the output section.

Thanks,

T D S

I'd say the limiter on the RBs doesn't kick in till you crank it hard, and it's for protecting the output section and speakers. Limiters are set to kick in only when you reach a certain threshold, otherwise they would be compressors, and I hear no compression in my RB110 at normal volumes.

 

[brianrost]

Limiters seem to be built into most class D amps, but are nowhere near as common in solid state class AB amps except old Peaveys...they called it DDT compression and most people disliked it as much as the limiters in class D amps today.

Agedhorse might comment on whether class D amps are more likely to fail from clipping and that's why limiters are used.

 

[agedhorse]

What does TCA stand for?

Transconductance amplifier, similar to a voltage controlled amplifier.

Limiters seem to be built into most class D amps, but are nowhere near as common in solid state class AB amps except old Peaveys...they called it DDT compression and most people disliked it as much as the limiters in class D amps today.

Agedhorse might comment on whether class D amps are more likely to fail from clipping and that's why limiters are used.

I've used a variety of limiter circuits going back over 30 years. It allows a designer to tailor the dynamics and response of a circuit as needed. I haven't encountered much of a perception of negativity with regard to the limiting algorithms that I have used, but like spices in food, it can't be overdone.

Most modern (quality) class D amp designs do not depend on limiters for failure prevention, but there may indeed be some designs that do require this. At this point, after 20 years designing around the ICEPower platform, reliability worries are not a concern.

 

[Yahboy]

Hello,

Do Rumble and Rocket Bass combos always have the limiter engaged while you're playing?

Or does it engage only when the amp is being pushed too hard?

Their user manuals seem to imply that limiting is just there to protect the output section.

Thanks,

T D S

My RB112 sound notable some compress effect especially on both E and A string while master volume on 4 o clock.
But with 2 RB112 stacked on, 3 oclock volume still has more headroom to go.

 

[G-Dog]

The Rumble V2 350's owner's manual describes Delta-Comp this way:

"Rumble bass amplifiers are equipped with Fender's Delta-Comp™ limiter to minimize power amp distortion and increase sustain. Setting the VOLUME control to higher settings or playing aggressively with hotter basses may result in a heavily compressed sound with increased sustain. Using the 6dB switch or setting the VOLUME control lower will provide a less compressed sound with more dynamic range and increased touch-sensitivity."​

While the Rumble V3 500 owner's manual has almost nothing to say about Delta-Comp:

"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!"​

 

[agedhorse]

There are 4 separate compressor/limiter circuits in the Rumble V3's, only one is used as a limiter for the power amp.

 

[FretRiff]

I'd say the limiter on the RBs doesn't kick in till you crank it hard, and it's for protecting the output section and speakers. Limiters are set to kick in only when you reach a certain threshold, otherwise they would be compressors, and I hear no compression in my RB110 at normal volumes.

A couple of years ago, @LowEndLobster switched from using an Orange Crush 50 to an Ampeg RB-110 for YouTube demos. The change was likely due to viewers (and possibly Lobster too) noticing compression caused by the Crush's limiter. That said, I don't remember the audio ever being pushed that hard in the videos.

In subsequent videos I do not recall comments about hearing compression from the Ampeg.