• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

Analogue Vs. Digital

#41
B-string said:
Makes me wonder if you only listen to cassette tapes and vinyl records? :D
Click to expand...

Ummmm, Pretty much yes for me (though only cassettes for old radio programs, etc...that are unavailable anywhere else).

It's all rather silly now though because many of my "analog" albums in the past 20 years were recorded digitally at some point and then masterd analog and slapped onto vinyl.

For me it's largely nostalgia and the love of all things tangible, but there is a difference between 1100011010001000 and a signal with endless shades of gray.

When it comes to amplification I have never been happy with solid state let alone digital. Some folks prefer things uncolored and monitor-like, but I love me some "warmth" and tubes give me that.

Particularly when you are talking about amplifying the living *** out of a signal like we do with basses the tubes bring a lot to the party. Some don't like this at all and some are happy to have it simulated by other means. To each their own...

Not for any real reason (other than I got it very cheap) I even have a tube flat screen HD TV...weighs slightly more than the sun...and the picture sucks...ha ha!
 
#43
There are digital class D amplifiers out there, but not many.

A typical class D amplifier is technically not analog or digital. It's a discrete system, which is sort of a cross between the two.

Like a digital audio system, a class D amplifier samples the input signal, and the samples are represented by on/off discrete states, again like a digital system, BUT the samples are not encoded into numbers. The samples are encoded into an on/off switching ratio.

A class D amp is always switching the output on and off. If there is no input signal, the on/off time ratio is equal, so the output is nothing and your speaker doesn't move. The samples change the ratio. When the ratio is changed, the speaker will move to follow because the output is no longer 50/50 balanced.

Digital audio...it's a code =

0111 1111 0000 1010
0111 1111 0000 1011
0111 1101 0010 1101
0111 1011 0000 1101

Class D audio...each line represents a switching cycle =

00000000011111111111 = speaker in the middle
00000000001111111111
00000000000111111111
00000000000011111111
00000000000001111111
00000000000000111111
00000000000000011111
00000000000000001111
00000000000000000111
00000000000000000011 = speaker moved out all the way
00000000000000000111
00000000000000001111
00000000000000011111
00000000000000111111
00000000000001111111
00000000000011111111
00000000000111111111
00000000001111111111
00000000011111111111 = speaker in the middle again
00000000111111111111
00000001111111111111
00000011111111111111
00000111111111111111
00001111111111111111
00011111111111111111
00111111111111111111 = speaker moved in all the way
 
#44
Well, sort of. In class D, the output devices are being switched on and off, but the output itself is switching back and forth between a positive voltage and a negative one; there is no "off" other than a very short dead time on each transition to ensure that a device is off before its complementary device turns on (because "shoot-through," where both are on simultaneously, would result in a catastrphic failure).

It would be more accurate to call the representation of class D audio shown a representation of loudspeaker cone position instead. That's because the output voltage from a power amp produces an accelerative force on the voice coil and cone, not a positional force.
 
#53
Another great explanation of class-d
Link Removed

Nice diagrams already. But if ascii is needed maybe something like:

- + - + - + - + - + ... speaker in the middle. Output devices are switching from negative rail to positive rail at an even rate - sum over time interval is 0. The number of + and - are the same over a time period. This switching back and forth is well above human hearing.


- + - + - + - + - + ... speaker in the middle.
- - + - - + - - + - - + ... speaker is moving backwards. sum over time is more towards the negative rail
- - - + - - - - + - - - + ... even farther back
- - + - - + - - + - - + ... moving forward from back
- + - + - + - + - + - + ... back to center
- + + - + + - + + - + + ... moving forward
- + + + - + + + - + + + ... even more forward
- + + - + + - + + - + + ... heading back to center
- + - + - + - + - + - + ... back to center

And now class-ab:
It's totally wacked out. The output devices there switch off for nearly half the cycle, but then switch into transconductance while on, until it switches back the other direction. Sometimes both sides are switched on. Gads, what a mess :hiding:
 
#54
BassmanPaul said:
If you continue to call valid information as jive talk you have little chance of ever understanding anything.
Click to expand...

I never said the information was not valid...I just don't understand all the technical answers I was getting. I called it jive talk... Sorry bad choice of words... I just wanted to know if the 4 pound amps could keep up with the 30 pound amps with the big transformers... just like I want to know if the neo cabs can keep up with the heavy magnet speakers. I don't know a dam thing about this light weight stuff. There is a couple of bass players in my town that use them and they all sound wimpy... could be just them and not the gear... I've listened to a lot of vids on you tube and they all finger slap and it sound very thin for my taste. I play rock and don't do any slapping so it's hard to judge what they really sound like. I'll probably just keep playing my 1998 Eden and keep my muscles tone up.
 
#56
2string1 said:
I never said the information was not valid...I just don't understand all the technical answers I was getting. I called it jive talk... Sorry bad choice of words... I just wanted to know if the 4 pound amps could keep up with the 30 pound amps with the big transformers... just like I want to know if the neo cabs can keep up with the heavy magnet speakers. I don't know a dam thing about this light weight stuff. There is a couple of bass players in my town that use them and they all sound wimpy... could be just them and not the gear... I've listened to a lot of vids on you tube and they all finger slap and it sound very thin for my taste. I play rock and don't do any slapping so it's hard to judge what they really sound like. I'll probably just keep playing my 1998 Eden and keep my muscles tone up.
Click to expand...

NEO speakers can and do surpass "heavy magnet" speakers.
JimmyM touched on it, some perceive a difference with lighter SMPS over old school big iron. Many don't until they lift the amp ;)
 
#57
In my view, yes, the lightweight amps can keep up. Differences in sound are likely to be limited to:

1. Preamp voicing, and virtually all preamps in bass gear still use conventional circuitry.

2. Overload handling, where there are both good and bad designs among both conventional and micro amps. How an amp handles being driven to full output may affect its loudness. The real designers on the forum have gone to considerable length to explain this aspect of amp design. I just nod my head and smile. ;)
 
#60
Bob Lee (QSC) said:
Well, sort of. In class D, the output devices are being switched on and off, but the output itself is switching back and forth between a positive voltage and a negative one; there is no "off" other than a very short dead time on each transition to ensure that a device is off before its complementary device turns on (because "shoot-through," where both are on simultaneously, would result in a catastrphic failure).

It would be more accurate to call the representation of class D audio shown a representation of loudspeaker cone position instead. That's because the output voltage from a power amp produces an accelerative force on the voice coil and cone, not a positional force.
Click to expand...

I ain't no engineer, but this seems right, based on what I know of such things.

That said, when it comes to bass amps I find that most of the Class D contenders can go way loud, but they just don't seem to push the speaker with the same kind of easy authority and control that I hear from tube or SS amps that have old school transformers. Some come closer to others - I've glommed onto an Aguilar TH500 that sounds pretty convincing, and I also use a G-B 3.0-10T as a rehearsal/coffee house amp. Words fail me, but a good Class A/B amp just seems to have push, ease, authority and space all at the same time. Which is why I ended up keeping a Thunderfunk 750A I was about to sell.

This is a different issue from digital/analog as a form of signal storage and playback - I still keep a turntable and have about 3000 vinyl albums, most from back in the day...Digital continues to improve, but other than background noise and extreme dynamic range -- and convenience -- I almost always find analog more satisfying than digital. And beware the signal-sapping data compression techniques of MP3 and the like - Ugh!
 

Latest posts

Top Bottom
Back