Can you explain the newer class "D" amps to me?

[Quickie]

Moot. If damping factor mattered no one would use an SVT, or any tube amp for that matter.
Invalid Link Removed

Beg to differ. High damping factor equals tight bass
http://www.google.com/url?sa=t&sour...2LyfDg&usg=AFQjCNHG4eEebAF_nFoLpGYoLDbCaHYs3A





Not going to get into a big discussion here. SVT'sa were designed for SEALED cabinets which themselves are a dampening design. Play an SVT on a ported cabinet and it sounds boomy. Facts are facts and your ear can hear the difference.

 

[JimmyM]

Not going to get into a big discussion here. SVT'sa were designed for SEALED cabinets which themselves are a dampening design. Play an SVT on a ported cabinet and it sounds boomy. Facts are facts and your ear can hear the difference.

Except this boominess you claim is in ported cabs when driven by SVT's isn't true in every case. I've played 20 butt-tons of SVT into ported cabs, and only the boomy cabs sounded boomy. The other ones sounded like ported cabs being driven with any other amp, except infinitely better sounding Seriously, that's an old wives' tale about ported cabs and SVT's.

 

[Quickie]

Except this boominess you claim is in ported cabs when driven by SVT's isn't true in every case. I've played 20 butt-tons of SVT into ported cabs, and only the boomy cabs sounded boomy. The other ones sounded like ported cabs being driven with any other amp, except infinitely better sounding Seriously, that's an old wives' tale about ported cabs and SVT's.

Again...not going to argue....same cabinet svt410 hlf SVT tube amp vs SVT 450 s/s amp. Very big difference. This was also the case when using both amps with an 810 svt cab. I owned them all at the same time for a few months.

I also tried a gk 800 rb....same thing. It sounded tighter. Now if it was just me....cool...but everyone heard the difference. Another industry that has done extensive research is the high end stereo industry on this. Articles all over.

 

[Quickie]

y'all posting inna TROLL THREAD

Sorry you feel that way. I'm not a troll, however, you can call me anything you like.

 

[JimmyM]

Again...not going to argue....same cabinet svt410 hlf SVT tube amp vs SVT 450 s/s amp. Very big difference. This was also the case when using both amps with an 810 svt cab. I owned them all at the same time for a few months.

I also tried a gk 800 rb....same thing. It sounded tighter. Now if it was just me....cool...but everyone heard the difference. Another industry that has done extensive research is the high end stereo industry on this. Articles all over.

Tube SVT has a giant midbass hump with all controls at noon. 450 is flatter when nooned. Gotta move those knobs if you want a flatter response with an SVT. I won't argue that it couldn't happen where an SVT was too much for a ported cab, but that's because of its voicing and its ability to really crank the low end. But it can be dialed out if that's your thing.

 

[Quickie]

A vibrating speaker coil will generate a signal called back EMF (Electro MotiveForce). Because back EMF is in opposite polarity with the speaker’s motion it willattenuate it. Since damping factor varies with frequency the amplifier with low outputimpedance will provide a mentionable damping for higher load impedances, such asfor a speaker in resonance. The effect of higher output impedance will definitively colour the sound since it “amplifies” the mechanical characteristics of the speaker itself. Some people regard the emphasized highs and enhanced bass introduced by free air resonance (typically around 60 – 120 Hz) as “warmth”. However, due to lesser damping during resonance the amplifier may also suffer from “flabby” or “farting”bass tone and earlier cone break-up

3.19.5 Ampeg SVT

 

[Quickie]

Tube SVT has a giant midbass hump with all controls at noon. 450 is flatter when nooned. Gotta move those knobs if you want a flatter response with an SVT. I won't argue that it couldn't happen where an SVT was too much for a ported cab, but that's because of its voicing and its ability to really crank the low end. But it can be dialed out if that's your thing.

The 450 SVT has significantly more low end than the SVT classic. That's one of the reasons I am getting another one.

 

[billfitzmaurice]

Beg to differ. High damping factor equals tight bass
http://www.google.com/url?sa=t&sour...2LyfDg&usg=AFQjCNHG4eEebAF_nFoLpGYoLDbCaHYs3A





Not going to get into a big discussion here.

No discussion necessary. Your link is culled advertising copy, hardly a definitive engineering treatise. Dick Pierce has forgotten more about how amps work than all the members here combined will ever learn, with the possible exception of Bob Lee. And there's no such thing as 'tight bass'. The response associated with that purely subjective term occurs in the lower midrange.

y'all posting inna TROLL THREAD

I tend to agree. There's an agenda here for sure.

 

[Quickie]

No discussion necessary. Your link is culled advertising copy, hardly a definitive engineering treatise. Dick Pierce has forgotten more about how amps work than all the members here combined will ever learn, with the possible exception of Bob Lee. And there's no such thing as 'tight bass'. The response associated with that purely subjective term occurs in the lower midrange.

I tend to agree. There's an agenda here for sure.

I see. I appreciate the "it's my way or no way" stance you are taking here, but the data suggest otherwise. And the most important thing...my EARS support it.

And an agenda? For asking how class D amps work?


That�s why speakers have brakes themselves, referred to as damping, in the electrical and mechanical elements that compose the structure. Larger magnets impose a greater braking force as the coil cuts through the magnetic field, and turn the motion into electrical current in the same way that the speaker turned current into motion. Any decent power amplifier then shunts this current. Frictional losses in the suspension absorb energy and turn it into heat.

Damping is described mathematically as a Q value. In loudspeakers, it describes the ratio of energy storage at resonance, to dissipation. The electrical properties have a Qes. The mechanical properties have a Qms. When both are combined to the cabinet�s Q value, a system Q is derived. High Q systems store energy for a long time, resulting in a longer delay and higher amplitude at resonance, while low Q systems get rid of energy quickly, providing a shorter group delay and a lower amplitude at resonance.

Damping in a speaker is absolutely critical. Otherwise, near the resonant frequency, rather than stopping, the woofer would go BOOOOOMMM, as well as bottom out, and destroy the voice coil former (a tube on which the coil is wound).

Essay

Some easy reading for you. Now, I see you are a speaker designer. Yet you state "there is no such thing as tight bass"?

Maybe you should read up on this a bit more. Where terms are used to describe the tone of the Ampeg 810 as "punchy" and "tight bass" have been stated from countless musicians, I guess since you say there is no such thing.......well you see where this is going.


On the original topic, thank you for posting the links.

 

[Mr. Foxen]

You realised you've already been fully undermined in your statements by JimmyM, who isn't a technical guy, but he is a guy who understands his equipment. you can make a valve amp, with its relatively low damping factor sound fine into cabinets that sound fine in themselves. Although the anigifs in that article are informative.

Musicians use inappropriate terms and excuses all the time. It is why they break their stuff all the time

 

[Quickie]

You realised you've already been fully undermined in your statements by JimmyM, who isn't a technical guy, but he is a guy who understands his equipment. you can make a valve amp, with its relatively low damping factor sound fine into cabinets that sound fine in themselves. Although the anigifs in that article are informative.

Musicians use inappropriate terms and excuses all the time. It is why they break their stuff all the time

Wow. Race car drivers also break their cars. However the terms "tight" or "loose" perfectly describes the real world conditions they have every time they step into their cars.

A degree is just a piece of paper, however ears are the true testing device.

 

[agedhorse]

Damping factor is only one part of cone control. There is not any clear cut number or value that defines the practical real world performance, but rather a group of perhaps 8 or more variables interacting that gives the impression of "tight bass". Even something as simple as the inherent voicing ofthe amplifier plays into the impression of how the low end feels. Directly comparing an SVT classic to any other model ignores the voicing difference as well as other (maybe intentional factors) that contribute to the feel of these amps through identical cabinets. The damping factor is a small part of this IME, primarily because it becomes larger at lower frequencies thus becoming more effective where needed the most. At higher frequencies, where DF naturally falls, there is far less stored energy in the moving mass. This is not as simple as you might believe.

 

[Quickie]

Damping factor is only one part of cone control. There is not any clear cut number or value that defines the practical real world performance, but rather a group of perhaps 8 or more variables interacting that gives the impression of "tight bass". Even something as simple as the inherent voicing ofthe amplifier plays into the impression of how the low end feels. Directly comparing an SVT classic to any other model ignores the voicing difference as well as other (maybe intentional factors) that contribute to the feel of these amps through identical cabinets. The damping factor is a small part of this IME, primarily because it becomes larger at lower frequencies thus becoming more effective where needed the most. At higher frequencies, where DF naturally falls, there is far less stored energy in the moving mass. This is not as simple as you might believe.

Remember......there is no such thing as tight bass. And that statement is from a speaker designer.

Thank you for your reply here horse. I appreciate anyone who will talk to me, rather than down to me.

 

[Mr. Foxen]

Hence the quotes and 'impression of' parts.

 

[Quickie]

Hence the quotes and 'impression of' parts.

I have been off the boards for a while due to a health issue. I will never forget a guy that used to get into arguments with so many people about tube life. How tubes in an SVT could last 30 years or more of constant use and not need replacement. Even though he had many post links about tubes needing replacement after so many hours of use. Even one guy posted Ampegs own recommendation to replace power tubes after so many hours. His reply, "it is a marketing ploy between tube manufactures to sell tubes", will always stay with me.

He had degrees also.

I guess things have stayed the same. I certainly don't have the knowledge that many here do, (as my original question proves) but getting into a big discussion here about something that is clearly audible wont change some minds no matter what data is presented.

You know, marketing ploys and all.

 

[agedhorse]

Remember......there is no such thing as tight bass. And that statement is from a speaker designer.

Thank you for your reply here horse. I appreciate anyone who will talk to me, rather than down to me.

There is the IMPRESSION of tight bass, there's also bass that is uncontrolled (mostly due to poor design) and there's everything in between. Understanding WHY these impressions occur is more difficult and complicated than just pointing to or blaming a single cause (that may be easy to market BTW).

 

[Quickie]

There is the IMPRESSION of tight bass, there's also bass that is uncontrolled (mostly due to poor design) and there's everything in between. Understanding WHY these impressions occur is more difficult and complicated than just pointing to or blaming a single cause (that may be easy to market BTW).

Cool. Thanks.

However, poor damping (control) of a speaker will have an effect on it's output, correct? So it's not an impression, it's a reality. Weather it's a long cable run from the head to cabinet, (many feet) introducing more resistance impedance etc, to poor amplifier control itself, damping can be heard.

 

[trevcda]

I'd been thinking of starting a thread in the vein of the OT, as I have a couple of questions.
How dependant on voltage are these amps? I ask because I used to have a couple racks of Carver PM1200s that sounded great if they had good solid voltage, but really sounded horrible if it started to sag. Bad enough that I went back to the old iron, despite them being much heavier. Now with GB Shuttle series and Ampeg offering a simular format of hardback book sized amps, I'm wondering if voltage sags will have the same issue.
Next question is why aren't guitar amp manufacturers embracing these amps? If you can fit all that bass amplification into a package that size, it seems like you could put a small guitar amp into a chassis the size of a zippo lighter! Half kidding of course.

 

[Pilgrim]

In trying to follow the thread, I thought that Class D amps have been explained pretty well - or at least as I could follow the info, they were.

As far as I'm concerned, the amp can be full of peanut butter. I let agedhorse and the other engineers deal with the "why and how". The important thing is that the amps deliver....and my class D amp does, and has done so without fail.

Such perceptions as "tight bass" are in the ear of the beerholder. They are also endlessly subject to change depending on the cabs used, the acoustic situation created by the room, and the number of people in the room, as humans change the acoustic situation.

I'll leave the "how and why" to you folks - both the amp engineers and the speaker designers...and more power to both of you! As a user, I plug 'em in, listen to them, and pick one to play through.

 

[TC2112]

This thread has been interesting reading, but it's all greek to me. Here is all I know - I run my GK 200 watt micro head into a 4 ohm 2x10 Yamaha cab for 4 or so hours a night for 3 nights a week (usually). It sounds great, with PA support for FOH, it's all I ever need to carry for the size club, bar and tavern type gigs I play, and it sounds great with a super punchy and "tight" response that I like to hear. So class D works for me.

My guitar player's brother is one of those super nerdy tech guys who builds tube amps and likes to restore old amps. Back when I first got the little GK, I asked him, how do they get 200 watts of power in this little bitty package - he responded that it was the same technology that can get huge wattage into small car type power amps - that was all the explanation I needed.