Does class D have the Heft of SS

[Figjam]

I had the use of a Sunn Concert bass head back in the day. Nice amp but, I never drove the output stage into clipping so I can't comment on that.

I think thats sort of the point. It never actually SOUNDS like its clipping. (so far) It just sounds better and better, hehe.

 

[AE1]

Sunn concert bass sounds great. Sounds like it compresses in the power section somehow, sort of like a pignose. Peavey Mark IV didnt clip badly either. Built in compressor may have helped.

My MKIV is the lowest powered amp in my Peavey stable but has the most features and is by far the best performing

Power output at 225 watts rms into 4 Ohms is low by today's standards but is adequate for average indoor gigs. Still enough to fry a 15 inch speaker.

The inbuilt DDT clipping prevention circuitry automatically prevents overload by limiting gain

The risk with independent heads is that if long speaker cables are too lightweight they can consume much of the power before it gets to the speaker. So if your clipping light activates that could be the reason.

But if you like the MKIV functionality it can be used as a preamp feeding a more powerful power amp

 

[agedhorse]

Unless the speaker cable is very long, the losses are going to be really small, even with 18 gauge cable at 225 watts into 4 ohms.

 

[Brad Johnson]

Because you can throw a class D/SMPS amp a lot farther than a class AB one with a conventional power supply?

Someone should start a "My power cord weighs more than my amp" club.

 

[Mark Andrew]

Refresher:

Does class D have the Heft of SS?

I had the same dilemma when buying the mini max the threads in TB I read just confused me further I now have three amps of different types and similar RMS ratings and regularly use and gig them all. The class d continues to impress me and although it falls a little short in oomph (when dialling in extremes of eq) and is less pleasing when directly compared. In a gig situation this is a non issue. I am using it more and more.... The old ss has mainly practice room duty the classic does the 500+ venues and the mini does the rest and is always on the bench ..... reliability is my only remaining question

 

[JimiLL]

So much has changed in pro audio that I doubt anyone could pin it all on just power amp technology, especially given the sheer amount of digital jiggery-pokery available in speaker processing these days. I love where the industry has gone on that end. However...



I (and a lot of other guys) still vastly prefer analog mixing desks to digital ones under the following circumstances: A. I don't have to move them; B. I don't have to mix multiple bands or chart them. I use digital desks all the time and they definitely make load-in/out easier and are great when you have a bunch of bands but if the only criteria I'm choosing on is sonics, it's an analog desk every time (particularly Midas). They are objectively not better than digital consoles but the bits of low order distortion in the channel strips and summing amps are quite euphonic and definitely add warmth to a mix. Digital desks don't have that despite all of their excellent features. Not saying that I can't get a nice mix with a digital desk but that I still prefer the less than perfect sound of an analog console.



I have done this. A bunch of years ago I was involved with some stringent AB tests of pro level power amplifiers with some industry heavyweights. These comparisons were between class AB/class H amps with conventional (i.e. heavy) power supplies and ones with SMPS. This was before class D was really a thing. We all went in with the idea that the SMPS amps would sound light (as that was the common thought about them) compared to the conventional ones. They demonstrated the importance of gain matching (louder system sounds better) and when the amps were gain matched, no one could tell them apart. This test did not get into operation near the limits of the amps but at the time my experience was that the conventional amps did behave better near/beyond clipping.

I've done similar tests between class-D (UCD, ICE) modules and AB modules of the same power in the design of a hifi system and again, below clipping I couldn't discern any difference.



I am not questioning your intelligence at all. However, asking whether the system is gain matched is a fair question as many people aren't aware that it needs to be done. Using the same preamp at the same settings into two different power amps doesn't ensure gain matching. You need to match the gains of the power amplifiers themselves. In your case, the DCM 1500 has ~33dB of gain and the Prolite has ~35dB (not a big difference but enough to have an effect) so in order to get a truly accurate comparison, you'd need to dial the gain back 2dB on the Prolite. Usually the louder (more gain) amp would be perceived as sounding better, but I'm assuming in this case you preferred the Carvin. How were they different? In general, I'd expect similarly rated power amps to sound virtually identical when gain matched and run well within their linear ranges but wouldn't be surprised if they began to sound different as they approach and pass the clip point.

Ok I must have confused your tone with your intent.

I found that the carvin amp wasn't louder than the crest, but instead it had a thickness in the lower mids that the crest did not. Interestingly enough, it was most noticeable when used in a band context, particularly against distorted guitars. It just didn't fill out the low mids the way the carvin did. The crest also imparted some high end clutter, which I didn't mind but there was a difference there too.

I sold the crest shortly after for I believe a $50 loss. Still using the carvin.

It would be an easier lift with the crest in the rack but a wooden 6 space filled to the brim is still growing to be not so light.

Ok do consider myself to have exceptional hearing, once upon a time a friend and myself were hanging in my room at my parents house watching tv, when all of a sudden I muted the tv and was staring off into space.

"Do you hear that" I said
"What are you talking about?" Answered the friend.
"I hear something " I replied.

So I got up walking around the room trying to hone in on this very quiet ticking.

I tracked it down to my leaking water bed, which was dripping on the carpet onto a newly established small puddle. I could hear the water slapping the puddle over the tv.

My buddy couldn't believe it

 

[lpbfender]

I am not discounting perception, nor am I discounting the artistic side of this... I spent over 30 years in the touring pro audio side of things at FOH in between my day job projects. I very easily and fluidly cross between the two worlds, BUT when double-blind listening tests disprove perception (including my own, as I'm not immune to wishing something might work better than it does), I am obligated to go with the facts rather than the perception, otherwise I am just propagating some of the same BS as I stand against.

Regarding the Class AB versus class D stuff, I have designed both types of amps, I have access to test equipment and set-ups that allow me to compare specific items without extraneous variables in a double-blind manner. When 2 power amps are driven by identical preamps (I mean identical down to well matched everything) and double-blind testing by players shows zero difference, how can I in good conscience say that one is better than the other... again that is perpetuating the BS that I stand against. That doesn't mean that I COULDN'T design in differences in either topology, but then that's not the topology responsible for the difference is it?

If class D doesn't work for you, for whatever reason, the world is awash with good used class AB amps for pennies on the dollar. I hauled off about 500 pounds of class AB amps (most working) to the scrapper because it wasn't worth the cost of selling and shipping it. In fact I could barely give it away for the cost of shipping.

Can't argue against the above double blind test design. Something tells me the smaller and lighter design of the class d amps influence perception.

 

[JimmyM]

Can't argue against the above double blind test design. Something tells me the smaller and lighter design of the class d amps influence perception.

I don't. That's why you do double blind testing but I am not deaf.

 

[agedhorse]

Can't argue against the above double blind test design. Something tells me the smaller and lighter design of the class d amps influence perception.

Absolutely. When you hide the size and weight the data changes... this can only be perception. It's a very powerful and honest feeling motivator, even in players who might feel otherwise.

 

[FrenchBassQC]

I went to a local music shop and I asked for an amp with heft, the salesman looked at me like this

and after half an hour like this, he left to go serve another customer.

 

[Brad Johnson]

I went to a local music shop and I asked for an amp with heft, the salesman looked at me like this View attachment 2803213 and after half an hour like this, he left to go serve another customer.

Using additional descriptors may help to get your point across.

 

[Brad Johnson]

Someone should start a "My power cord weighs more than my amp" club.

Then again, "My power costs more than my amp" club...

 

[FrenchBassQC]

Using additional descriptors may help to get your point across.

It was a joke, you do not like jokes?

 

[Brad Johnson]

It was a joke, you do not like jokes?

It was a joke...

 

[ThisBass]

Note: My Peavey Tour 700 has a 1000 watt power transformer so is conservatively designed - but I have still added more filter capacitance to improve bass response.

That's one of the most possible abuse mods done to an amplifier without knowing the meaning of charging capacitors. Without any ripple the capacitors would have actually no more chance to charge and discharge energy from the mains transformer transfered to the rails.

DIY guys like it to reduce ripple with way oversized highish C numbers. Actually (doing those mods) they do nothing but decreasing current charging angle along the capacitors while peak current along the capacitors is dramatically incresed. In access doing this DIY mod an MI amplifier may sound odd versus properly designed supplies.
In Germany we tell it this way "der kann von Kraft kaum laufen"
Translation into English words (hope it works just to understand the meaning), it sounds like "Way too much muscle mass to be quick"

 

[Mark Reccord]

Ok I must have confused your tone with your intent.

I found that the carvin amp wasn't louder than the crest, but instead it had a thickness in the lower mids that the crest did not. Interestingly enough, it was most noticeable when used in a band context, particularly against distorted guitars. It just didn't fill out the low mids the way the carvin did. The crest also imparted some high end clutter, which I didn't mind but there was a difference there too.

I sold the crest shortly after for I believe a $50 loss. Still using the carvin.

It would be an easier lift with the crest in the rack but a wooden 6 space filled to the brim is still growing to be not so light.

Ok do consider myself to have exceptional hearing, once upon a time a friend and myself were hanging in my room at my parents house watching tv, when all of a sudden I muted the tv and was staring off into space.

"Do you hear that" I said
"What are you talking about?" Answered the friend.
"I hear something " I replied.

So I got up walking around the room trying to hone in on this very quiet ticking.

I tracked it down to my leaking water bed, which was dripping on the carpet onto a newly established small puddle. I could hear the water slapping the puddle over the tv.

My buddy couldn't believe it

Sorry, I should have clarified, I wasn't the poster you originally commented on there, that was Seamonkey. I just wanted to make it clear that it wasn't my intention to call your intelligence into question with my post.

Someone should start a "My power cord weighs more than my amp" club.

Then again, "My power costs more than my amp" club...

Both of these could be a thing. And the members of the second one would automatically be members of the first with very few exceptions. The most expensive power cable I ever auditioned was over $10k US. The rep asked me what I thought of it and I told him that the 16AWG IEC that I used to test the amp sounded just as good. He was floored that I didn't gush over it. It was funny.

 

[AE1]

Refresher:

Does class D have the Heft of SS?

Much of the discussion in this thread has been about pro audio systems - which means full-range PA

But let's remember we are talking BASS here

The difference between a good quality amp and a mediocre amp in the bass frequency range is its ability to deliver constant power down to the lowest frequency to be amplified

Manufacturers quote "frequency response" at one watt rms but what happens at rated power ?

Compare the rated power at 1 kHz to rated power at 40 Hz and you will see why some amps deliver better bass

i.e. - if a power amp delivers 100 watts at 1kHz and only 80 watts at 40 Hz then that will be heard as weak bass

You can offset this to some extent with preamp tone controls and graphic EQ but that approach requires a higher rated amp

But ultimately the limitation will be heard if the power is cranked up far enough - we cannot replace what is not there in the first place

Maybe this characteristic is what is described as "heft"

The PA pros I know use their best amps for the sub woofers - i.e a split system for highs, mids and lows

 

[seamonkey]

The difference between a good quality amp and a mediocre amp in the bass frequency range is its ability to deliver constant power down to the lowest frequency to be amplified

Class-d is more efficient, so given the same power supply there is less waste as heat, and more can go to actual output.

I'd like to see some standards of measure. I like to see a real continuous power rating, a real average power rating. I got no use for burst power rated down in milliseconds.

It only takes some manufacturers to agree. Consumers must demand it. And hopefully it's not legislation, but actual cooperation. Right now manufacturers have gone just the opposite route. Choosing to not agree and argue that their methods are the single best approach to ratings. Pure divergence based on marketing.

If there is something such as "heft" some amps are going to have some aren't. It is not the class that determines it but actual design and measurement. Measurement again some mutually agreed on standards.

 

[Jim C]

Much of the discussion in this thread has been about pro audio systems - which means full-range PA

But let's remember we are talking BASS here

The difference between a good quality amp and a mediocre amp in the bass frequency range is its ability to deliver constant power down to the lowest frequency to be amplified

Manufacturers quote "frequency response" at one watt rms but what happens at rated power ?

Compare the rated power at 1 kHz to rated power at 40 Hz and you will see why some amps deliver better bass

i.e. - if a power amp delivers 100 watts at 1kHz and only 80 watts at 40 Hz then that will be heard as weak bass

You can offset this to some extent with preamp tone controls and graphic EQ but that approach requires a higher rated amp

But ultimately the limitation will be heard if the power is cranked up far enough - we cannot replace what is not there in the first place

Maybe this characteristic is what is described as "heft"

The PA pros I know use their best amps for the sub woofers - i.e a split system for highs, mids and lows

 

[Jim C]

The assumption is that the specs reported are accurate.
As with many items, the interpretation of the data can be suspect.
My question is, assuming this perceived differences are real (which I believe they are), could one accurately measure it from amp to amp?
Of course, without a nationally accepted standard test plan and procedures, it can all become meaningless.