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Does class D have the Heft of SS

#62
I have to wonder how big a role an amp's high pass filtering and speaker's low frequency cutoff has in the perception of heft. The way I define heft relates to how the system delivers midbass and sub 100 hz content. An amp/speaker combination with heft will sound solid and tight with just a touch of bloom that holds on a bit after the midbass punch has ended. An amp with an aggressive HPF or a speaker that does not go low enough will not produce what I call heft. For example in my book, an SVT into an 810 is more about grunt than heft. A Mesa M9 into a fEARful 1515/66 would provide an abundance of heft.
 
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#63
I think the thread is too general. I love my Orange TB500 through a good 15" cab. It's the sound of rock, and can do old-school really well. No heft missing vs my old Eden WT-400. I love tube heads too but have no occasion the play them. I think there may be more sonic differences within "class D" than between it and traditional SS.
 
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#66
ive owned all types of amps. tube ss and class d. i like and hate models of all categories but what i found for class d that i have tried and liked are gallien kruegar, warwick lwa1000 or lwa500, and mark bass all make great class d amps. warwick lwa1000 takes the cake tho for me. its now the only amp head i use
 
#68
I think it's in the voicing, it's tricky to get it perfect. I've had half a dozen Class D micros and wasn't happy with their tonal heft until I tried a Kustom KXB-500. From my experience this amp is something of an anomaly. Very authoritative voicing with plenty of heft yet neutral instead of the old scooped tone that used to be commonly encountered.
 
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#72
When I was on tour in the 80's and had roadies moving things around, huge tube amps were just fine. when I was living in NYC and had to move amps & cabinets around all the time "by myself" I switched to a Woods and single 15 cab. And I honestly can't remember anybody complaining. now I have a Streamliner 900 and Revsound 210. my back loves it. and frankly after playing professionally for 50+ years, my ears really can't hear enough of a difference to justify beating myself up any more.

of course YMMV
 
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#73
Wasnex said:
Lower weight, higher power, and more efficient use of available AC power would be my guess. Also because they can afford to buy enough to run them well within rated power limits.

However, in my limited observations (approximately 15-20 amplifiers), when comparing two amps with the same power rating, one class-D and one traditional, the traditional led sled will typically have more dynamic headroom and will also handle overload conditions more eloquently. Thus in a setting where the user is pushing the amps to or perhaps beyond their limits, the traditional design will tend to sound better. Certainly not a problem for a top touring company as they usually have enough speakers and amplifier power that they never approach clipping. I would say more relevant to the DJ market where clipping is essentially part of the sound. Also possibly relevant to Talkbass members who push their amps to the limits.

Not sure if my observations are valid anymore, as I haven't compared amps in several years. Perhaps my observations came down to manufacturer design/rating choices. It just seems odd that within individual companys' product lines, the led sleds seemed to be consistently have far more dynamic headroom than the light weight designs.

Thanks for the opportunity...I have wanted to hear your position on dynamic headroom and overload characteristics of led sled versus class-D amps for quite some time.
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I don't think this is the case, certainly not in the last 10 years anyway. If somebody wants the sound of a clipped amp, well I suppose that's their own personal taste, but the DJ market has nothing to do with the real pro audio market.

One of the reasons why class D amps are preferred for subs is the increased damping factor that is possible with this topology. Another is the improved stiffness of the power output by recycling the back emf of the speaker into the opposing power supply rails. Yet another reason is the freedom from SOA limitations, thus reducing the effects of VI limiters due to approximating of reactive loads within the protection curves. And, by improving the efficiencies (greatly), this means that the AC service remains stiffer (less voltage sag) and more real power delivered to the load is possible.

R Baer said:
I don't think you really can't compare custom, pro audio designs to what's in the typical class D bass amp, as I doubt the pro grade touring amps are all using the same $80 off the shelf OEM modules under their hoods like we are seeing in the bass market. Let's face it, a good percentage of class D bass amps are all using the same modules, so it's not really not correct to have topology discussions about the heft of "Class D" vs Class A/B when referring to bass amps. Any conversation is greatly biased towards player's experiences with the few class D modules (probably 90% IcePower) on the bass market compared to the tons of class A/B designs players have been using for decades. I think that's an important distinction for people to understand.

IMO, the term "heft" relates to the differences between the OEM class D module's (again, I'm not referring to class D as a topology) ability to sustain the note after the initial burst peak and in the way they are much more linear when compared to a traditional toroid powered amp as the volume increases. There are differences in these two areas that are picked up on by some people and this is what I believe people are talking about when they refer to "heft".
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Roger, many of the pro audio class D designs are based on exactly the same design approaches that we are using in today's OEM style power amp modules, and in fact some are based on exactly the same modules. In fact, on the newest series of modules, there is almost NO sag from the initial 20msec which represents MUCH BETTER performance that the more saggy line frequency power supplies.

When comparing different designs with different preamps, the power amps can not be directly compared because of the amount of variability that the preamp brings to the table. I have, however, compared the identical preamp with different power amps specifically normalized to determine the differences (for design inclusion purposes), and if the player doesn't know what is in the box (true double-blind test), my experience does not show that the player can accurately identify a solid state linear power amp (class AB/G/H) from a class D power amp. I've done many of these such tests, and it's always interesting when the results are revealed.

DiMarco said:
It IS exactly the cabs that matter as all class D amplifiers have one thing in common: poor damping factor. This makes class D unfit for reproducing low frequencies by design as in this region of the audio spectrum damping factor matters most. The result is whimpy sounding low end.

Not all speakers are as easy to control by an amplifier, especially if that amp has a poor damping factor.

NOT A SINGLE SOLID STATE BASS AMP MANUFACTURER ever mentions the damping factor of their amps but it is very important in bass amplification. Perceived power level will be much higher if the amp is keeping a firm grip on the speakers. Class AB poweramps simply do a better job at this then Class D amps have done so far.

Tube amps handle this differently and tend to sound more powerful in both the low and high end anyway. For a good read on this matter visit This website
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This sir, is not accurate information. The damping factor for one of the modules that I am currently designing around is >1500 at 8 ohms and >800 at 4 ohms. The reason for this is that the power devices operate in either cutoff or saturation, therefore the damping factor is almost purely a factor of Rds-on plus the impedance of the output reconstruction filter choke. In the particular design that I am working on, this comes to <5mOhms which is significantly lower than the best closed loop output impedance on a linear amp. All of the past designs that I have worked with were all greater than 400 at 8 ohms and 200 at 4 ohms. Compare this with the damping factor of a typical solid state power amp bridged at the same power (such as an RMX-850 which does 850 watts into 4 ohms BTL) and the DF is right around 150.

In fact, class D topologies are generally much BETTER for reproducing low frequencies. By your same argument that high damping factor is so critical to the low end performance of a bass amp, (linear) tube amps tend to have the lowest damping factor of all topologies represented in the bass world, perhaps by a factor of 5 or 10 or even more. Tube amps typically run under 50 best case, often under 25.

I did at one time include damping factor into the specifications, but after having to explain what it meant, and how it was calculated, and why so much emphasis was attributed to this single, sexy, one number specification, that I gave up and leave those sleeping dogs alone. It is probably one of the least useful spec's available, once the number goes above say a couple hundred.

Clearly, you are struggling with your understanding of this topic. may I suggest that you study up a learn a bit more about this subject before bringing a factually incorrect argument to the table presented in such a definitive way.

R Baer said:
I disagree. There are real behavioral differences between the OEM class D modules being put in today's bass amps and what you get from from a typical class A/B design. Whether or not those differences are perceptible to all players, or make one topology better than another is simply a matter of opinion, but they do exist.
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There are differences in every single design. The problem arises when cause and effect are attributed for the wrong reasons, leading to a perpetuation of old wive's tales (that are in themselves typically based upon very early, poorly executed designs).
 
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#80
BadExample said:
Hardly traditional.

Edit: well I guess I should say a torrid is hardly conventional or classic or something like that. They may be traditional to A/B SS amps...
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Well it does use a power supply that are not normally associated with class d amps. That has been used in amps for many many years so yes traditional in that sense.
 

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