Does class D have the Heft of SS

[GreyBeard]

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In only 29 pages ?

Let's wait and see what Andy thinks about this.
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I don't have anything better to do

 

[BadExample]

I think it all has to do with high-pass filters. That extra THUMP (heft) you feel from an amp that doesn't have a HPF, compared to one with a 30-50 hz HPF.

I think that's unlikely. Without an HPF, you have to "spend" a lot of your amps power producing subsonic stuff you can't hear... maybe you can feel it if you are at close range. Your VC in the drivers also have to endure a heck of a lot of power that it can't really use to move the cone. I don't believe the sub 30 Hz(ish) content is what you are missing. Of course, I could be wrong. I often am

 

[agedhorse]

I think it all has to do with high-pass filters. That extra THUMP (heft) you feel from an amp that doesn't have a HPF, compared to one with a 30-50 hz HPF.

Don't forget the special sounds that the speakers make as they tear themselves apart when the good common sense isn't as good as assumed. Speaking for speaker manufacturers in general, such amps are sometimes called speaker destroyers (in the wrong hands), and are responsible for damaged speakers that might have survived had there been a HPF. A speaker manufacturer that offers a very long warranty on their product might not feel quite so cavalier about such an amp.

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Possibly, but whether the filter is at 30 or at 50 would make a significant difference alone, as well as the order (steepness) of the filter.

Is it not the Mesa Subway D-800+ which on the front panel lets us continuously adjust the frequency point of the HP filter ?

I have a standalone graphic EQ (ART) which also contains such an adjustable filter.
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Regarding HPF's, if you look into how many players are actually using their variable HPF's you will see that a lot end up between about 40-60Hz, rather than the default (30Hz), and this is a 24dB/octave filter with a compound alignment. We started out at a bit less than 25Hz, but nobody preferred this in testing and some felt that it got in the way of the open low mid voicing so we moved it up to 30Hz which was the lowest that no player objected to.

Your ART eq has a very different kind of filter, a simple 12dB/octave Butterworth... good for its intended purpose but not ideal for serious low end control without getting into areas where it may impact tone (negatively). Just a different tool. Incidentally, this feature was copied from a Yamaha Eq that was the first product that I am aware of including it... about 35 years ago. Same slope and possibly the whole eq is "that" similar.

 

[Mike Arnopol]

I think it all has to do with high-pass filters. That extra THUMP (heft) you feel from an amp that doesn't have a HPF, compared to one with a 30-50 hz HPF.

With a good HPF you get MORE heft and thump in my experience. Heft and thump are not products of the 30 to 60 hz region. With a speaker that can easily handle that region---that low stuff is almost like a low cushion--it's not flabby or boomy. When someone says a speaker has a "huge" low end--I go running. Typically flab and boom on the low notes are a speaker that's flapping around aimlessly. Boominess is not in the 30 to 60 hz range. It's higher. Most bass players don't know what a fundamental on the B string sounds like. That's because the cabinets are tuned in the 45 to 50hz range. Below the tuning point the speaker is unloaded---it's bouncing around like it's in free air. If you throw information at it below 30hz---it's even worse. How well do you think a speaker can reproduce 64hz---the second harmonic of an open B if its flopping around trying to reproduce gunk in the subsonic range? If you are hearing a lack of heft in the low end with an amp with a HPF it's likely a poorly designed HPF that's squashing things dynamically. One advantage of a sealed box is that it doesn't unload. But it has to be insanely huge or insanely inefficient to reach those goals. Andy Lewis of Acme tunes his reflex cabinets pretty low. That's why his go lower than most cabs. But the price you pay is lower efficiency. I think that he struck a good balance.

 

[BurningSkies]

I think that's unlikely. Without an HPF, you have to "spend" a lot of your amps power producing subsonic stuff you can't hear... maybe you can feel it if you are at close range. Your VC in the drivers also have to endure a heck of a lot of power that it can't really use to move the cone. I don't believe the sub 30 Hz(ish) content is what you are missing. Of course, I could be wrong. I often am

I agree. I've been using not one but two HPF's set in the 30's. It doesn't reduce 'heft' in tone, it reduces really 5hitty deep low wash in the the room. I still believe heft is the ability to handle transients effectively.

 

[Brad Johnson]

Because of variables. Ive used the TH500 with an Ampeg 810, Mesa 215, SWR 8x8... Ive also used a Trace Elliot head, the MB200, a Hartke LH500, Hartke 3500, QSC 2450, Ampeg SVT4PRO, Crest CA9, GK 700RB, MarkBass LMII each with one of those cabs. I used the same basses for either band as well as the same cables. Additionally Ive tried out tons of different heads in a store setting and its always the same thing with the Class D amps. They sound awesome but once you clear bedroom levels they start to fall short.

Most importantly, I used the Aguilars pre section into the Crest and heard the difference immediately. Even my non-gearhead drummer and singer/guitarist said they could hear the difference. Said that the Crest had a presence in the room that the other simply didnt.
Dont get me wrong, the Aguilar is an AWESOME piece of gear and very useful. But at the end of the day, the lead sleds simply sound better to my ears and chest. Its the immediacy and density of the low notes that do it for me.

For full disclosure Im in two bands. In one I am commonly playing a Zon Sonus6 with the bass upped a bit and a lot of slapping. In the other I am playing a Jackson CMX upgraded with EMG CS/DC pups and BQS Preamp and a TON of very fast picking as it is black metal.

Thanks. That helps paint a clearer picture. What are the impedances of the cabs?

 

[Passinwind]

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Forgive my ignorance, but which makes/models might some examples of those be ?

EDIT :

I see you later mentioned the Crown K2.

Other than the 62 or so pounds each, were you pleased with it ?

Any other examples ?
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The K2s actually weighed around 38 pounds each, but the Anvil style rack was a very heavy piece in its own right. For my bass wants and need I found them to sound just as good as my PLX 1804, which weighed 1/3 as much and fit easily in a short plastic EFX rack. I also drew the same conclusion for the CA9 a friend lent me for A/B/X testing. No better, no worse, and much less haul friendly. But I would hardly call myself your typical bass player, FWIW.

Off the top of my head I can't think of any more pro sound examples, but for bass amps: Aguilar AG500, Euphonic Audio iAmp 800, and a couple of the Spanish Hevos models come to mind. The fact that we don't see more amps built this way could just be instructive...

 

[agedhorse]

With a good HPF you get MORE heft and thump in my experience. Heft and thump are not products of the 30 to 60 hz region. With a speaker that can easily handle that region---that low stuff is almost like a low cushion--it's not flabby or boomy. When someone says a speaker has a "huge" low end--I go running. Typically flab and boom on the low notes are a speaker that's flapping around aimlessly. Boominess is not in the 30 to 60 hz range. It's higher. Most bass players don't know what a fundamental on the B string sounds like. That's because the cabinets are tuned in the 45 to 50hz range. Below the tuning point the speaker is unloaded---it's bouncing around like it's in free air. If you throw information at it below 30hz---it's even worse. How well do you think a speaker can reproduce 64hz---the second harmonic of an open B if its flopping around trying to reproduce gunk in the subsonic range? If you are hearing a lack of heft in the low end with an amp with a HPF it's likely a poorly designed HPF that's squashing things dynamically. One advantage of a sealed box is that it doesn't unload. But it has to be insanely huge or insanely inefficient to reach those goals. Andy Lewis of Acme tunes his reflex cabinets pretty low. That's why his go lower than most cabs. But the price you pay is lower efficiency. I think that he struck a good balance.

Agreed, and when a cabinet's response is already underdamped, exciting it with that extra unproductive energy can exaggerate the flabby sound that might get in the way of the desirable tone.

The other really big problem, especially on the high Xmax drivers, is when the speaker is moving at 20-something Hz +/- say 6mm, and is simultaneously reproducing say 2kHz. When this happens the motion forward of the cone increases the effective frequency and the motion backwards of the cone decreases frequency of the 2kHz tone. It's no different than a train whistle approaching or receding, the doppler effect. This is one of the two major disadvantages of long excursion drivers (which can be helped with the use of a HPF). Intermodulation distortion or doppler effect distortion is pretty interesting and relevant stuff in bass speaker design, something to always keep in the back of your mind.

 

[Brad Johnson]

I tried the streamliner, shuttle, ampeg 7, mesa, fender. Been to performances with bands I'm familiar with playing some of those plus the TC.
I will admit, the markbass I heard was impressively good though.

Markbass caused a lot of confusion because people thought the Little Mark II was class D due to its light weight. And running an 8 ohm load was not its forte'. Run it where the load was 4 ohms and it was pretty sweet.

I have a Shuttle 9.0 and a Kustom KXB500. People have been shocked at what I've gotten out of them in live situations. What you do with the gear can have a profound effect on the outcome.

 

[iammr2]

Ok, I've read the thread and I'm going to throw in my uneducated 2 cents here on the OP's question.

As far as "heft" goes, MordBass got closest to it for me so far, saying, "...the lead sleds simply sound better to my ears and chest. Its the immediacy and density of the low notes that do it for me." The K2 and the CA9 have it. Others?...I don't know. Another word I use to describe it is that the sound has "authority". Notice I said sound, not tone. It's like getting hit by a wall of sheer power when you pluck a note. Someone else mentioned that over time, smaller amps just put out sound. That kinda sums it up for me, IMHO. If the AG500 or the D800 have that "authority", please let me know.

 

[Jim C]

Class D vs. others

Could you guys touch upon the subject of slew rate and damping factor?
I've read the Wiki version.
Back in the day, big numbers was considered a barometer for quality.

As I understand it, slew rate is not a measured item in class D and, "according to the web", the damping factor is not as good.
I am curious what you amp designers, engineers, and speaker gurus can help others navigate through the confusion.
TIA

 

[Mike Arnopol]

Agreed, and when a cabinet's response is already underdamped, exciting it with that extra unproductive energy can exaggerate the flabby sound that might get in the way of the desirable tone.

The other really big problem, especially on the high Xmax drivers, is when the speaker is moving at 20-something Hz +/- say 6mm, and is simultaneously reproducing say 2kHz. When this happens the motion forward of the cone increases the effective frequency and the motion backwards of the cone decreases frequency of the 2kHz tone. It's no different than a train whistle approaching or receding, the doppler effect. This is one of the two major disadvantages of long excursion drivers (which can be helped with the use of a HPF). Intermodulation distortion or doppler effect distortion is pretty interesting and relevant stuff in bass speaker design, something to always keep in the back of your mind.

exactly. Wow---Andy and I agreeing on stuff--that's just plain weird. It's funny how people react to using a HPF. Things like "wow there's more bass and it's tighter" and "there's more midrange clarity". That's one reason that I started going with higher power midrange drivers and crossing them over lower. That way if some doofus uses 1000 watt amp without a HPF the bass will get weird but at least the midrange retains clarity.

 

[DavesnothereCA]

The K2s actually weighed around 38 pounds each, but the Anvil style rack was a very heavy piece in its own right. For my bass wants and need I found them to sound just as good as my PLX 1804, which weighed 1/3 as much and fit easily in a short plastic EFX rack. I also drew the same conclusion for the CA9 a friend lent me for A/B/X testing. No better, no worse, and much less haul friendly. But I would hardly call myself your typical bass player, FWIW.

Off the top of my head I can't think of any more pro sound examples, but for bass amps: Aguilar AG500, Euphonic Audio iAmp 800, and a couple of the Spanish Hevos models come to mind. The fact that we don't see more amps built this way could just be instructive...View attachment 2809293

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But of course - the rack itself had to weigh SOMETHING ! - Mine always have. - Unless it is one of those newfangled Class 'D' racks which I heard were being beta-tested a while back.

I was mainly interested to know whether any Class D solid state output stages had been utilized BEFORE s/s power amps in general became lighter in weight, and if so, what reception the amps using them received.

It would seem that Class D did not get much (if any) main stream attention until servo-controlled fans replaced larger heatsinks, and switching mode power supplies replaced conventional ones, each transition contributing to the slimming process.

I can only wonder what % (or ratio) of duty cycle was being incorporated in the Crown K2 and any of the other examples which I thank you for mentioning.

And just as amps like the K2 had a conventional power supply (I think that either you or maybe Andy said so today in another post), I wonder conversely whether any Class AB amps were produced and sold using switching supplies, and how that played out. - I think I recently read here that some did, but I forget which ones and who posted it.

Yes, I'm leading up to something, but I think it deserves a new thread, and I had better compose my OP offline for a few days, before launching it.

Thanks
~

 

[DavesnothereCA]

....It's funny how people react to using a HPF. Things like "wow there's more bass and it's tighter" and "there's more midrange clarity". That's one reason that I started going with higher power midrange drivers and crossing them over lower. That way if some doofus uses 1000 watt amp without a HPF the bass will get weird but at least the midrange retains clarity.

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Yes, I was thinking about that while composing my last post, because I had also read Andy's comment about a @2KHz signal getting dopplered by a woofer which was also trying to move the distance required to reproduce something else at the low end.

It ought to work nicely if it doesn't drive up the overall price of the rig too much, which would depend in large part upon whether it was passively or actively crossed between the woofer and the mid driver.
~

 

[jnewmark]

Don't forget the special sounds that the speakers make as they tear themselves apart when the good common sense isn't as good as assumed. Speaking for speaker manufacturers in general, such amps are sometimes called speaker destroyers (in the wrong hands), and are responsible for damaged speakers that might have survived had there been a HPF. A speaker manufacturer that offers a very long warranty on their product might not feel quite so cavalier about such an amp.



Regarding HPF's, if you look into how many players are actually using their variable HPF's you will see that a lot end up between about 40-60Hz, rather than the default (30Hz), and this is a 24dB/octave filter with a compound alignment. We started out at a bit less than 25Hz, but nobody preferred this in testing and some felt that it got in the way of the open low mid voicing so we moved it up to 30Hz which was the lowest that no player objected to.

Your ART eq has a very different kind of filter, a simple 12dB/octave Butterworth... good for its intended purpose but not ideal for serious low end control without getting into areas where it may impact tone (negatively). Just a different tool. Incidentally, this feature was copied from a Yamaha Eq that was the first product that I am aware of including it... about 35 years ago. Same slope and possibly the whole eq is "that" similar.

I think you talked about this before, but I could not find it. Suppose you wanted to use two HPF's, one at a fixed frequency in the amp itself, and an outboard pedal, like the Fdeck HPF. For example, I know my Shuttlemax12.2 has a built in HPF, but suppose I wanted to get in the range of 45hz. Would using the Fdeck, ver. 3 which has the following info : " The "12+12" filter curve is two filters in one. The first filter has a fixed corner frequency of 35 Hz, and 12 dB/octave slope. The second filter is adjustable from 35 to 140 Hz, and also has a 12 dB/oct slope. Thus it always has 24 dB/oct slope below 35 Hz", interfere with the built in HPF on the 12.2 , or would it just pick up where the Shuttlemax HPF leaves off ?

 

[mikewalker]

I'd just like to interrupt with a public service announcement on behalf of HEFT.

Invalid Link Removed WEIGHS ONE HUNDRED AND FIFTY-EIGHT POUNDS!!!
"HEFTY"
​

 

[DavesnothereCA]

....Regarding HPF's, if you look into how many players are actually using their variable HPF's you will see that a lot end up between about 40-60Hz, rather than the default (30Hz), and this is a 24dB/octave filter with a compound alignment. We started out at a bit less than 25Hz, but nobody preferred this in testing and some felt that it got in the way of the open low mid voicing so we moved it up to 30Hz which was the lowest that no player objected to.

Your ART eq has a very different kind of filter, a simple 12dB/octave Butterworth... good for its intended purpose but not ideal for serious low end control without getting into areas where it may impact tone (negatively). Just a different tool. Incidentally, this feature was copied from a Yamaha Eq that was the first product that I am aware of including it... about 35 years ago. Same slope and possibly the whole eq is "that" similar.

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Yamaha, eh ? - Not surprised to hear that.

And I think that you posted something the other day (in response to another of my posts) about the Mesa Subway D800+ having a cascaded HPF which was part fixed and part variable.

Still, using that 12dB/oct filter in the ART EQ would be better than nothing, I would think, especially if the person would set it to a bit higher shoulder frequency than really desired, and then somewhat boost one or two of the 1/3 octave bands on the same EQ channel, at or just below the chosen shoulder frequency.

This is of course speculation on my part, but I plan to try it soon, now that I have thought of doing so, and since my current head has no HPF.
~

 

[agedhorse]

There are many amps with class AB/G/H output stages and SMPS. It was a very popular topology while class D amps were gaining popularity. Heck, I even designed a couple.

Cascading 2 HPFs at 35Hz each will always result in the combined HPF frequency higher than either. Depending on the alignment, I would expect the summed frequency to be between 1/3 and 1/2 octave higher than 35Hz.

Compound filters can be very useful provided the frequencies and alignments are well chosen.

 

[murphy]

And just as amps like the K2 had a conventional power supply (I think that either you or maybe Andy said so today in another post), I wonder conversely whether any Class AB amps were produced and sold using switching supplies, and how that played out. - I think I recently read here that some did, but I forget which ones and who posted it.

My Mark Bass SA450 and LMII are class AB with SMPS

 

[seamonkey]

I'm not believing that a HPF reduces the functional bass Heftons (FBH)

Headphones, earphones can easily do let's say 15hz and filtering out below 30hz does nothing to the FBH in the sound.

I'm guessing usable functional heftons (UFH) are way up at 60-70hz, but the majority hear them at 100-120hz as super engergized heftons (SEH)

Of course, class-d can pass ultra low heftons (ULH) down to 0hz, a few early amp makers didn't account for this and passed through destructive heftons (DH). The ones you can't hear but destroy drivers.

Headphone (good ones), good music, or good synth, and EQ and listen for all hefton categories.
Somewhere there has to be an app for displaying hefton categories so we all can agree on which heftons are important.