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Does class D have the Heft of SS

#21
There is an unquantifiable sound I've experienced only from a tube amp in the past. That is the combination of the Ampeg SVT all tube head and an 810 cab. Old which would probably be called "classic" today, some 20 plus years later. I toured with that combination in a loud band. There is something magical about the sound, the feel of the enveloping tube sound and eight pumping 10" speakers that I might equate to "heft." No amp I've ever played through since had that special shoe vibrating tone and fullness since. Today it would be impractical for me to try and schlep something like that around a small town. But boy, what a tone! Heft!!!.

Given my limitations nowadays the Class D "SS" amps today do a wonderful job of creating a big sound when needed. But they will never match that sound I used to love out of the old SVT Fridge rig I was lucky to use in the past. Again, though, I can carry a Class D in my gig bag and I own multiple ultralight cabs that make full sounding stage presence and ease of transport. Long live Class D!
 
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#23
OP, what are you trying to say by using the word "heft"?
Plus, Class D amps are SS amps.


heft
(hɛft)

n.
1. weight; heaviness.

2. significance; importance.

3. Archaic. the bulk or main part.
v.t.
4. to test the weight of by lifting and balancing: He hefted the spear for a moment and then flung it.

5. to heave; hoist.


 
#25
It used to matter a lot.

In the 80s and 90s, solid state amps couldn't compare to tubes. It wasn't close.

If you wanted that warmth and heft to your tone, you had to go with tubes. SS amps sounded cold and sterile.

But, technology has pretty much caught up, and there are some damn good preamp pedals out there that can build that bottom end that was previously only available with tubes.

I love hybrid amps, with tubes preamps, but that's because I'm old and cranky!
 
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#27
MrCash said:
Why do some say class D amps are lacking in Heft!?
Click to expand...

Because their preamps are voiced differently.
Just as some older SS amps lack heft.
I own, or have access to multiple older SS amps and a few class D ones. While i have the feeling that the TH500 has some HPF in place that you don't feel when you're on a 4 string with the E your lowest note, but start feeling with a Sub octaver in place on a five string, i have class D amps that pack a punch down low and lead sled SS amps that don't.
as an example, there is an old Trace Elliot SS head with 200W sitting in one of the rooms i rehearse in. My little Mark II, set to the same volume packs a punch through my 412 where the Elliot does not.
 
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#28
agedhorse said:
Would anybody care to explain why every pro audio touring amp handling subwoofer duty is solid state, and just about all are class D as well?

This is in a market with 6 and 7 figure budgets too...
Click to expand...

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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#29
"Heft" is a real thing perceptually . But I'm not sure what it is in physical terms. I had an Eden Wt-300 (or was it a 400..?), one of the nice USA ones. Not a featherweight. But no heft. My Trace Elliot AX500x had tons of heft. Everybody including my drummer and my non-musician wife could hear it (and she thinks my active J and passive P sound identical!). Even if you cut the bass on the Trace and boosted the bass on the Eden, the difference was still there. So it's not a simple frequency response thing. A mid-scoop can add the impression of depth, but I don't believe that's the whole story.

My Aguilar DB750 had incredible heft, even more than my SVT II. The Fender Super Bassman 300 has it too. The Mesa M9 has it, as does the Strategy. The GK 1001 has some but less. These amps have even less (even though I love most of them): shuttleMax 9.2, streamliner, svt7pro, MB800, KXB500.

So what is it? It's not tubes. It's not power/headroom. Some of the class D amps have a HPF, but I don't think all of them do. Maybe it's the transformers. I get the impression the newest generation of class D amps has de heft (I haven't heard any in person).

With a good speaker cabinet and in a live situation it doesn't matter *that* much, but I still wonder what causes the difference, and even what the difference actually is. I can hear it, but I'm not convinced that there is actually more low frequency content, even though it feels like there is.
 
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#30
Martin Beer said:
I think it would be a fun experiment to take the same ICEpower module that many of the micro heads use, mount it in a 4U rack case with a couple of bricks for extra weight, then see if bassists could hear the "heft" when compared to the micro heads!
Click to expand...

I think TC Electronic already did this.

image.png
 
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#32
I don't know all the technical stuff, but I have owned Tubers, AB's and D's. My primitive conclusion is that it is more of an issue of the signal going in. Whether or not my view is valid technically, it seems that a lot of AB's and D's "expect" to have a preamp in front of them, on board or outboard of a bass. So, I gladly oblige by putting my Hartke Bass Attack in front, I have both types. Heft, fat, girth, grunt, old school tone, whatever you choose to call it. I can get about anything in any direction so far as an unusable extreme.

All good by me. I got stung by an early BX500 croaking outside if warranty, but I decided not to throw out the baby with the bathwater. My current class D is a honey.
 
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#33
The first class D amps when they appeared sounded spongy in the low end. When I slap the low B I want the earth to tremble. With these amps this would not happen. For this reason I have not considered trying one out for a number of years.

But besides them lacking this "in your face" hefty low end qualities back then, there's also that buttery yet articulate tone you seem to get from (preamp) tubes only. Some amp designers try to mimic it but then it usually just gets buttery without being articulate any longer.

I have owned a lot of amps in the past, and before the days of class D lightweight I usually went for used market hybrid design Trace Elliot SMX amps as I could not afford a tube amp.

I really loved those SMX amps with their tube pre and dualband compressors. They had SS power sections and a pre that would let you blend between a buttery sounding 12AX7 tube- and a SS pre section. I used to love those amps... But ever since switching to a full tube design I now find even those SMX amps sound rather bland and boring. The Bass Prodigy is just much more responsive and lively sounding.

So when a guy came by to test an Eden D212XLT cab he was wanting to buy from me with his own amp we A/B'd between my all tube Prodigy and his class D TH500... Not having heard any of the current class D amps I was very intrigued about how this little fella would sound. Long story short it sounded rather weak and it had no impact in the booty region whatsoever. It being an Aguilar I had expected it to sound somewhat beefy but nope. Very disappointing and to my ears thin sounding. Wouldn't ever spend money on one of those.

I am not saying ALL class D amps lack heft, but a lot of them seem to. This means you will have to test drive for yourself when shopping for a new (lightweight) amp. I have yet to encounter the first class D bass amp that will impress me but I know to never say never.

Don't buy a sexy looking lightweight amp off the internet. Do test thoroughly before buying.
 
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#34
MrCash said:
Why do some say class D amps are lacking in Heft!?
Click to expand...

As others have said, it is largely to sell their non class D amps. There's also an element of what I call the "cult of the old and crappy" - folks want to cling to anything more than 20 years old as if it's special, no matter how bad it is.
There IS some truth to the notion that some of the first class D amps weren't so great - nor were some of the first solid state amps (or tube amps, for that matter) - but today's Class D amps range from cheap& bad to expensive and *great*. Like everything else, you will get what you pay for.
 
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#35
agedhorse said:
Would anybody care to explain why every pro audio touring amp handling subwoofer duty is solid state, and just about all are class D as well?

This is in a market with 6 and 7 figure budgets too...
Click to expand...

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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#39
Guys who play class D will tell you all day that the only heft theirs is missing is the weight you lug to a gig. Couldnt be farther from the truth. Ive yet to play a class d that has anywhere near the authority of my 1200 watt solid state amp in the mix. They sound great in light mixes and in your bedroom, but in a rock mix its like a kazoo.
 
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