Class D Amps

[Mr. Foxen]

[quote name='stingrayPete1977' timestamp='1378284189' post='2197994']
Do they make valve in ear monitors?
[/quote]

Hearing aids were valve, still use hearing aid power valves in pedals sometimes. Pretty similar concept.

[Ziphoblat]

[quote name='discreet' timestamp='1378284495' post='2198001']
Yes - here they are in action.


[/quote]

[peteb]

[quote name='sk8' timestamp='1378281568' post='2197966']
LM2/3 are not class D. There are A/B and sound the better for it IMO. Side by side the LM 500 sounded far more organic than the 800 watt with the class D power module
[/quote]
That may explain why I prefer Mark Bass to other lightweight amps that I've tried...

[JTUK]

[quote name='xgsjx' timestamp='1378274674' post='2197888']
Pros have roadies to lug the gear. Me, I run into a venue with combo in one hand, pedalboard in the other & bass slung over my back & set up as quick as I can.
If it's just a straight does heavy sound better than light, then my Markbass combo sounds far better than the 8 ton 4x10 Trace Elliot combo I had & also far better than the Carlsberg, Peavey or Marshall things I had prior to that.
[/quote]

Tbf, everything has moved on... and some of those amps weren't a high bar in the first place...or rather I certainly recall a few horror stories..

[4 Strings]

[quote name='Count Bassy' timestamp='1378298183' post='2198274']
Go on then.
[/quote]

The old water analogy. Volts is pressure and amps is volume. You can't have water pressure with no water volume, nor can you have any volume flow with zero pressure.

[4 Strings]

[quote name='discreet' timestamp='1378254149' post='2197855']
So if you're just dabbling go with a class D... and if you're a pro go with a big valve amp..? [size=4] [/size]
[/quote]

The other way round. If you're dabbling, big amps are fine, if you need to be playing a lot and therefore shifting your gear a lot, the little stuff is life changing.

Actually, my littl'un has a Class A valve preamp and a Class D power amp.

[lee4]

MarkBass LMII in a camera case,Zoot 2X12.Case around neck,cab in one hand,bass in the other.
Bliss.

[nottswarwick]

But this thing is my heavy amp is not really that heavy. Nor was my EBS350. Nor my Ashdown. All easy to carry in a nice rack case. Ok, it 4kg, granted, but I'm not only talking about massive Mesa 400s or all valve ampegs here.

For me it's the cabs that are awkward if heave, hence my light cab.

[Dood]

Moving on from the 'Digital' thing..


Actually, I've stumbled upon an amp I really like in this lightweight revolution. I posted about Matrix Amplification the other day. I've seen that their amps have been really rated in driving PA systems, especially subs and bass units so I was pretty keen to try one out for bass.

Anyway, the short of it is that I am really liking their GT1600 power amp more so than other light weight amps I've tried. (though i still have a few big faves in D Class world)

What I've found is that the GT1600, a 1.6KW shallow rack amp that still only weighs 4.7Kg has a lot of balls. The design is an AB (not D) class power amplifier strapped to a custom SMPS (Switched Mode Power Supply). There is a lot of heft in the lows that reminds me of my ole Powersoft D2004 power amp - but i like this better.

ok, so I'm not a nutter or anything lol - its 1.6K bridged or 800W per channel... Quite happy running a single channel heh!

Anyway, my point is, that if it's the 'AB' bit of the design that is driving those deep lows - then I like AB amps

[xgsjx]

[quote name='JTUK' timestamp='1378313305' post='2198504']
Tbf, everything has moved on... and some of those amps weren't a high bar in the first place...or rather I certainly recall a few horror stories..
[/quote]

I know. The only one's I had that I liked was the Peavey & the Marshall. But still not a patch on the MB.
I've used some good sounding heavy rigs in the past too (just didn't own them).

[scalpy]

Does your amplifier help you enjoy yourself? That includes the whole transport / stage footprint/ contentment of soundman and other occupants of the stage experience. If yes, then it's fine.

[Guest bassman7755]

[quote name='Count Bassy' timestamp='1378290819' post='2198118']
Well a class D amplifier is digital in that its output devices are either ON or OFF, much like a digital computer. (Same as a switch mode power supply)
[/quote]

Class D amps use pulse width modulation i.e. varying on-off pulse lengths, its still fundamentally (IMO) an analogue process since the pulse widths are "analogous" to the original signal voltage and have a theoretically infinite precision. In order for something to be "digital" it must involve encoding the signal as a number (which necessarily has finite precision).

To explain it another way, a class D amp translates an analogue voltage signal to an analogue time domain signal, then back to a much bigger analogue voltage.

Edited September 4, 2013 by bassman7755

[discreet]

[quote name='dood' timestamp='1378319440' post='2198621']
Matrix GT1600 power amp...
[/quote]

I'm liking the look of it!
[url="http://matrixguitaramplification.com/products/gt1600fx-2u-rackmount-amplifier/"]http://matrixguitara...ount-amplifier/[/url]

T'would go well with my newly-acquired SVP Pro...

Edited September 4, 2013 by discreet

[BassTractor]

[quote name='bassman7755' timestamp='1378321499' post='2198660']
its still fundamentally (IMO) an analogue process
[/quote]

Nonsense! It IS an analogue process. Keep your IMOs to yourself, sir.
BTW, made me remember how some people would never get that a Compact Disc is an analogue medium (admittedly for digitally encoded info).

[discreet]

[quote name='BassTractor' timestamp='1378327176' post='2198791']
...made me remember how some people would never get that a Compact Disc is an analogue medium (admittedly for digitally encoded info).
[/quote]

I had the same problem making people understand that video tape is analogue and film is essentially digital.

[Dood]

[quote name='bassman7755' timestamp='1378321499' post='2198660']


Class D amps use pulse width modulation i.e. varying on-off pulse lengths, its still fundamentally (IMO) an analogue process since the pulse widths are "analogous" to the original signal voltage and have a theoretically infinite precision. In order for something to be "digital" it must involve encoding the signal as a number (which necessarily has finite precision).

To explain it another way, a class D amp translates an analogue voltage signal to an analogue time domain signal, then back to a much bigger analogue voltage.
[/quote]

Explained it better than I would! Cheers Bassman.

[Dood]

[quote name='discreet' timestamp='1378321645' post='2198665']


I'm liking the look of it!
[url="http://matrixguitaramplification.com/products/gt1600fx-2u-rackmount-amplifier/"]http://matrixguitara...ount-amplifier/[/url]

T'would go well with my newly-acquired SVP Pro...
[/quote]

I've ran it up with my SVP-BSP, a distortion preamp I'm pretty fond of and have to say, it sounds great. I'd recommend the valve pre with it, yup.

[Count Bassy]

[quote name='bassman7755' timestamp='1378321499' post='2198660']
Class D amps use pulse width modulation i.e. varying on-off pulse lengths, its still fundamentally (IMO) an analogue process since the pulse widths are "analogous" to the original signal voltage and have a theoretically infinite precision. In order for something to be "digital" it must involve encoding the signal as a number (which necessarily has finite precision).

To explain it another way, a class D amp translates an analogue voltage signal to an analogue time domain signal, then back to a much bigger analogue voltage.
[/quote]

I think we're arguing over semantics here. I agree with what you're saying* and our two views not incompatible.

In my view however because the output devices are either on or off I'd still call it digital ([i]albeit with a 1 bit resolution[/i]), as opposed to analogue where the output devices can be any state between on and off. The fact that it's a PWM output, doesn't (IMO) make it any less digital.If a bit in a computer is going on and off at varying intervals that doesn't make it analogue does it?
Yes after the various output filters, and frequency response of the speaker, the resulting signal is analogue, but the output devices themselves are still working digitally I.e. they are on or off, like bits in a PC.

[color=#282828][font=helvetica, arial, sans-serif] *Apart from: "In order for something to be "digital" it must involve encoding the signal as a number (which necessarily has finite precision)." I'm not sure on the details of digital amps, but I know that in digital servo drives the actual PWM is generally controlled by a DSP - a digital device.[/font][/color]

Edited September 4, 2013 by Count Bassy

[Dood]

My desk lamp is digital!




I love lamp

[Count Bassy]

[quote name='BassTractor' timestamp='1378327176' post='2198791']
Nonsense! It IS an analogue process. Keep your IMOs to yourself, sir.
BTW, made me remember how some people would never get that a Compact Disc is an analogue medium (admittedly for digitally encoded info).
[/quote]

Nonsense! It is a one bit digital process.

And a CD is not an analogue medium, any more than a computer hard disk is. It is a digital representation of an analogue signal. I.e. a collection of 1s an 0s, which are combined to represent and approximation to an analogue value.

Edited September 4, 2013 by Count Bassy

[Count Bassy]

[quote name='4 Strings' timestamp='1378316285' post='2198567']
The old water analogy. Volts is pressure and amps is volume. You can't have water pressure with no water volume, nor can you have any volume flow with zero pressure.
[/quote]

I'm talking about the output/switching device, not the load.

If you turn a tap off then you get no water flow (current), but the full mains water pressure (voltage) remains in the pipe work behind it. i.e. the full mains water pressure is lost across the tap.
If you turn the tap fully on then you get a large water flow, but the pressure loss across the tap is practically zero (depending on the size of the tap and the flow). The pressure loss is now across your sprinkler or whatever (loudspeaker).

Either way the energy dissipated in the tap is (ideally) very small.

[Count Bassy]

[quote name='dood' timestamp='1378328830' post='2198834']
My desk lamp is digital!




I love lamp
[/quote]

This I agree with as long, as you ignore the 50Hz sine wave !

[BassTractor]

[quote name='Count Bassy' timestamp='1378329082' post='2198837']
Nonsense! It is a one bit digital process.
[/quote]

Hm. At face value, you sound a lot more serious than I was in the post you respond to.
Whatever the case may be, I'm not able to have a serious talk about the degree to which certain elements in processes and concepts are this or that - in a language that is not my own. Nor am I willing to on this forum.

[Count Bassy]

[quote name='BassTractor' timestamp='1378329935' post='2198857']
Hm. At face value, you sound a lot more serious than I was in the post you respond to.
Whatever the case may be, I'm not able to have a serious talk about the degree to which certain elements in processes and concepts are this or that - in a language that is not my own. Nor am I willing to on this forum.
[/quote]
Perhaps I should have stuck a smiley on there! To be honest I'm not really that bothered either, it's all just words, and what they sound like is the important thing. I think the only digital/class D amp I've ever played through is GB shuttle 9 (Not mine) it was only at practice volume and sounded fine to me.

[ead]

[quote name='Count Bassy' timestamp='1378329082' post='2198837']
Nonsense! It is a one bit digital process.
[/quote]

OK I think I understand where you are confusing analogue and digital. The control aspect of class D amps are often driven my MOSFETs which act like switches (or indeed by digital controllers), however these components are controlling an analogue waveform and you have to consider the difference between analogue and digital in terms of how they are quantised. The amps are not digital in the sense that they do not deal with discrete voltage levels (steps).