Class D amp at full volume?

[Drgonzonm]

Time for a new class of amplifier.
Then the naysayers and misunderstanders might quit picking on the Ds.

I'm not picking on them, the amp I'm using just happens to be Class D and I wanted to find out if there was anything to know in the scenario I was describing... definitely not a naysayer as I much prefer the smaller more efficient gear.

Hey, I love the class d amps, I am tired of picking up 40 lb tube amps, and 60 lb SS amps. I like the fact that amp combos are being sold in 2x varieties with external cab plugs. I have my methods of knowing whether that high wattage amp really produces 2000 -3000 watts on a 120v circuit.
I will also say, there are times to bring out the dinosaur amps and cabinets. I have a few myself.

 

[Brad Johnson]

It actually isn't academic - I am using a small (220w) Class D amp that with my two not overly efficient but very portable 1x12 cabs is borderline loud enough in my usual comfort zone of not using the last quarter or so of the main volume control, having adjusted the preamp gain to be on the edge of clipping and the EQ to push through the mix a bit. What I was trying to ascertain was, given there is plenty of power handling in the cabs, if there was something inherently unwise about using that remaining available power if I need to. I think we have established that it's ok to use

I obviously could buy a larger, more efficient and much more powerful rig, but having just got rid of my old school big gear would prefer not to go back down that route.

?

Getting a more powerful newer smaller head wouldn't be going down the same road.

 

[Brad Johnson]

If weight is the concern, 4 to 6 x the power of what you have now might weigh about ten pounds or less. You don't look so frail

Try less than 4 lbs.

 

[Brad Johnson]

I do know that psychologically, a lot of people are averse to turning the burners on their stoves to full blast or actually "flooring" their car accelerator.

That kind of thinking keeps people from doing all sorts of things. It helps to understand the capabilities of your tools and it's funny when you can demo someone's gear to them and show them what they never realized they already had.

It goes both ways. We had a small local get-together and I brough my amp which has only four knobs. We got a ton of different sounds out of several basses.

A friend had bought an expanded version of a popular head and when I asked him why he chose it I think it struck him as he was answering how funny his answer was...

"It had more knobs". Because before he played my amp he'd thought that more was automatically better. His basses sounded great and didn't require "fixing" or help.

 

[Drgonzonm]

It actually isn't academic - I am using a small (220w) Class D amp that with my two not overly efficient but very portable 1x12 cabs is borderline loud enough in my usual comfort zone of not using the last quarter or so of the main volume control, having adjusted the preamp gain to be on the edge of clipping and the EQ to push through the mix a bit. What I was trying to ascertain was, given there is plenty of power handling in the cabs, if there was something inherently unwise about using that remaining available power if I need to. I think we have established that it's ok to use ....

.

I would consider upgrading the speakers, and keeping the cabinets.

 

[monkeyfinger]

I would consider upgrading the speakers, and keeping the cabinets.

Then you would have to find speakers that are designed to work with those cabinet dimensions. This is no small feat. I would recommend getting a different cab. It may cost more, but the results would be more predictable.

 

[alaskaleftybass]

That's +1.5dB power in reserve.
IME the deviation of both the dynamics (respectively transients) and average even for players with darned good playing technique should be considered as > +3dB.
Without compressor and/or distortion pedal Its not possible to (really) exactly gain not more than 70% of amp reserve.

Well, @ThisBass a little embarrassed to say, but my method is less than scientific than yours. I meant don't crank the volume controls more than 70%, and now that I think about it, if you have to push your amp that hard to keep up, maybe up the power. But I don't use a lot of scientific reasoning. I just eyeball the controls. I keep nearly all the tone controls at 12:00 and normally the Pre at 9:00-11:00.

 

[alaskaleftybass]

I don't know if @Passinwind or @agedhorse has been by, but I would like to hear what their opinion is. As I mentioned in the above post, and the previous, a little common sense goes a long way. If you are maxing out your amp you do not have a powerful enough amp.

 

[AE1]

What would be the rationale for having a volume knob that goes to 10 if you could only safely run it at 9?

Sorry to challenge your reasoning but the number on the dial means absolutely nothing - other than a guide to where the pointer on the knob is in its range of rotation travel (some knobs do not have a pointer at all)

It has no relationship to the power output other than comparing the setting to zero because the measure of power output is your ears - i.e. how "loud" it sounds compared to zero power out

The zero base level is actually the background noise level in the room, which can be expressed in db. That means whatever power is needed to offset the ambient noise level is essentially lost.

In other words if a knob setting of 2 is adequate in a quiet room then it will not suffice in a crowded hotel bar or dance hall

Then you need to consider the rate of change of the control. Volume controls in hi-fi amps and radios etc use a logarithmic taper rate of change to enable fine adjustment at low volumes, but guitar and bass amps typically use a linear taper control. That results in a rapid change in volume for a small change in rotation.

The effect of that is that once the linear control is set past the number 3 or 4 position, not much happens.

In relation to "gain" the amp/preamp system has an overall gain expressed as a ratio of Gain:1. - i.e output voltage divided by input voltage. It's called "amplification". That is what an amplifier does.

Gain is expressed as a fixed number (which may be in "db") so the output of the system is controlled by the input signal strength (voltage)' Less in, less out.

That means you can set the amp/preamp volume controls to 10 and control the volume directly from your bass - which usually does not have numbers on the dial. My preference is to set the main control to full and adjust with the preamp. This helps to prevent overloading the preamp section before the main amp and/or the input stage to the main amp. Also minimises background hum and noise - especially in tube amps with minimal internal feedback.

Since there is no standard for gain as such you will find one amp will have high gain whereas another will have low gain.

Most amps have a "high" and "low" input - that refers to gain, not input load impedance.

Each has its uses

As to "full power" it seems operators of PA systems are compelled to drive them into serious overload to impress the audience. This produces a garbled mess of sound, so if you want to emulate that approach go for it.

But in the case of BASS it will be the speakers which are most likely to pay the price for running the system at full power - in a normal bass rig they do not have overload protection

Finally, another answer is look at the speedometer on your car - same question applies. In that case if you are on an icy road and plant the foot the speedo can show 100 mph but you might be standing still. Not quite the same as a volume control but the principle is the same - the numbers only mean something in a definable context.

 

[Drgonzonm]

Then you would have to find speakers that are designed to work with those cabinet dimensions. This is no small feat. I would recommend getting a different cab. It may cost more, but the results would be more predictable.

without further data, The post was a generalized post. a good place to start is replacement speakers for the cabinet. I am guessing that each cabinet is 8 ohms, together 4 ohms. Maybe your 220w amp will handle a 2 ohm load, then choose 4 ohm speakers.
The way I look at it, portability is important to you.
The speaker frames have manufacturer data on them. There may be later and updated models.

 

[agedhorse]

Both limiters and compressors belong to the family of VCA signal processing tools.
I don't think that limiters are cheapy in general while compressors can be of high quality.

Perhaps the poster doesn't understand or care to understand and parrot some Internet myth?

In my world we really like being able to flip a switch and engage a back-up when something goes wrong. If there's no way to design out this frequent failure with a simple modification, the switch idea is a brilliant one in my mind.

Yes, except for the voltage involved...

I bought it real cheap at a garage sale. 20 years ago. A friend who did electronic repairs had it in his shop for about 18 months. The original owner forgot about the amp, or didn't want to pay the repair charges. The friend was closing down the shop. and This blind squirrel found an acorn. I believe I paid $10 for it.

After 18 months, the original owner should have throttled the technician. That's an absurd amount of time.

I have my methods of knowing whether that high wattage amp really produces 2000 -3000 watts on a 120v circuit.

Which apparently you still don't understand.

 

[Al Kraft]

Yes, except for the voltage involved...

...oops...well sometimes there are problems that that a switch can solve, and other times you find new reasons to appreciate the guy who invented the parachute...

 

[agedhorse]

A shocking experience

 

[Drgonzonm]

After 18 months, the original owner should have throttled the technician. That's an absurd amount of time

Which apparently you still don't understand.

1. I don't know the details, but tech turn over time typically was very short. Imo, bad comment.
2. If I see the quoted numbers, and The amp has a iec cord, the numbers numbers are fluff

 

[Son of Wobble]

"I'll give ya 120 volts!"

 

[dbsfgyd1]

It actually isn't academic - I am using a small (220w) Class D amp that with my two not overly efficient but very portable 1x12 cabs is borderline loud enough in my usual comfort zone of not using the last quarter or so of the main volume control, having adjusted the preamp gain to be on the edge of clipping and the EQ to push through the mix a bit. What I was trying to ascertain was, given there is plenty of power handling in the cabs, if there was something inherently unwise about using that remaining available power if I need to. I think we have established that it's ok to use

I obviously could buy a larger, more efficient and much more powerful rig, but having just got rid of my old school big gear would prefer not to go back down that route.

Unfortunately, your problem is with your cabs, not your amp. It is cheaper, more cost effective per db to increase speaker area or efficiency of your cabs than to increase wattage, or specifically, increasing your power to your cabs. They can only handle X amount of power. Just a couple of ideas to help, keeping your cab up against a wall will increase the amount of db from your rig. Second, if you can find a corner, better yet.

 

[mesaplayer83]

without further data, The post was a generalized post. a good place to start is replacement speakers for the cabinet. I am guessing that each cabinet is 8 ohms, together 4 ohms. Maybe your 220w amp will handle a 2 ohm load, then choose 4 ohm speakers.
The way I look at it, portability is important to you.
The speaker frames have manufacturer data on them. There may be later and updated models.

You don't seem to understand that replacing speakers in a cab is definitely NOT "a good place to start"...

 

[agedhorse]

2. If I see the quoted numbers, and The amp has a iec cord, the numbers numbers are fluff

No sir, you simply can not understand how the rest of the world, including every certified rating agency, calculates power consumption on ALL audio equipment. Trust me, you are wrong and the rest of the world is right on this one.

By the way, most big pro power amps, including your revered lead sled amps, utilize the same IEC inlet connector. It's not a conspiracy.

 

[fdeck]

I want to suggest a couple of extreme cases, just for the sake of illustration:

1. You turn up all of the knobs, but put no signal into the amp. Maybe you get more hiss, but the amp can run forever in this way, without blowing up.

2. You turn the knobs to what seem like moderate settings, but feed a huge signal that drives the power section of the amp to its utter limits. The amp might run for anywhere from a few minutes to a few hours depending on the design, before probably going into protect mode.

I've tested my own amps with signal generators and dummy loads, and gained a certain sense of what they were capable of, but eventually got tired of that exercise, and haven't done such rigorous testing on my most recent amps. The DIY bass amp that I built long ago was certainly capable of running full tilt, indefinitely. It was over-designed by a wide margin. A later DIY attempt had weird failure modes when overloaded, and I abandoned it quickly when I understood what was happening.

The moral of the story is that the knobs by themselves don't tell you whether you're pushing an amp to its design margins or not.

 

[Al Kraft]

If I see the quoted numbers, and The amp has a iec cord, the numbers numbers are fluff

I'm a little slow when it comes to the world of electronics, but can you expand on this a bit. In my mind, an IEC cord is simply how electricity gets connected between the power outlet on the wall (or where ever it's located) and the unit being powered.

I would think the only things you can accurately conclude from looking at the cord are which end plugs into what and total power the cord is rated for (voltage and amp rating stamped on the side and some quick multiplication). The amp itself, depending on the design and other factors, could have a range of perfectly valid output and total power usage ratings that would would be impossible to conclude from the power cord itself. What am I missing?