Class D amp with the most slam/punch

[Ben Clarke]

Why is there air?

lol, maybe still too soon for that reference!

 

[pfschim]

ask better questions, get better answers.

yep! great reply.

whether intended or not, the OP asked a somewhat loaded question with some false assertions (eg. "only big amps hit like that"
'that slam only a big amp can do) and loose/poorly defined terms ....i.e. the ever popular Slam/Punch/Heft etc.

This is TB, where you get to pose a question but you don't get to control the responses. You're going to get serious, thoughtful replies, you're going to get snarky replies, you're going to get pushback on your premise, and sometimes your just going to get silly replies (which I personally like as they can add comic relief). And the OP did get some opinions on Class D amps that "slam", so it's not a total loss.

enjoy!

 

[DJ Bebop]

Why is there air?

lol, maybe still too soon for that reference!

 

[bertthebassist]

OP, from my observations of reading TB for almost a decade, and having owned a DB751, I guestimate that about 15% of TB understands and/ or likes the feel, sound, heft & slam you are talking about, based on responses from multiple threads.

I purposely bought a DB751 just to find out what everyone was talking about. A very expensive mistake. Ever since, I have been churning through gear on an endless quest to find that sound in equipment that I don't mind carrying.

The 15% who like Heft (which I define as the deep bass/ sub bass), like the neck pick up, enjoy sound below 50 hz, can distinguish and hear below 50 hz (not just the harmonics), and dislike HPFs. They like the fullness of sound at low and/ or high volumes. I define Slam as higher volume Heft where you feel the notes.

An 88 key piano goes from 27.5 to 4,186.0 Hz. I can hear all of the keys.
Why anyone would want to remove the bottom octave of their bass, beats me. If it sounds like mud, maybe you have the wrong equipment or can't hear that low.
Piano key frequencies - Wikipedia

I have not found an amp that sounds like a DB751 yet.
Honorable mention are: Mesa M6, M9 and GK 700RB, 1001RB.
Lightweight amps that I felt got closer than others are: Aguilar AG700, Eich T900, GR Bass ONE 800
Cabinets that seem to go deeper than others (IMO): Aguilar SL115, GS412, Fearful 12/12/6/1, Bergantino HS410, NV215, GR Bass AT212.

Heft sounds good in some styles of music and is not used in others, which may explain why there are so few who care about Heft & Slam.
Heft is sometimes replaced with synthesizers which can go lower than a piano or 5 string bass. Maybe we should be looking at keyboard amps.

 

[agedhorse]

Regarding piano, there's not much generally being played on the bottom say 1/2 octave because within a mix, it really becomes indistinct and many pianos struggle with it because it can excite non-musical "stuff" that is not terribly pleasant. Occasionally as an effect or where an arrangement might benefit, but as a generality it's avoided. I play piano and I certainly have no need for that bottom 1/2 octave, heft or no heft.

An example of this in practice is the Yamaha CP-70 which was the most toured electric piano (with a piano action and strings) in the world back in the day, intentionally dropped the lowest notes because they got in the way for most amplified music, and the number of strings per note (only one string on the lowest ~octave) was reduced to simplify the tone so that it would sit better in a mix. It was about cleaning up the tone for amplification and frankly it sounded better and was easier to mix without the low frequency mud. This is also what drives high pass filters, which have been around for 40 years in pro audio and used on a lot of "over-hefty" bass rigs to clean them up and sit them in a mix.

Heft or lack of heft (or slam, or whatever) is not about elite-ism, it's more about appropriateness and balancing the different needs for improved compromises that result in a better end product.

 

[richntiff]

Regarding piano, there's not much generally being played on the bottom say 1/2 octave because within a mix, it really becomes indistinct and many pianos struggle with it because it can excite non-musical "stuff" that is not terribly pleasant. Occasionally as an effect or where an arrangement might benefit, but as a generality it's avoided. I play piano and I certainly have no need for that bottom 1/2 octave, heft or no heft.

An example of this in practice is the Yamaha CP-70 which was the most toured electric piano (with a piano action and strings) in the world back in the day, intentionally dropped the lowest notes because they got in the way for most amplified music, and the number of strings per note (only one string on the lowest ~octave) was reduced to simplify the tone so that it would sit better in a mix. It was about cleaning up the tone for amplification and frankly it sounded better and was easier to mix without the low frequency mud. This is also what drives high pass filters, which have been around for 40 years in pro audio and used on a lot of "over-hefty" bass rigs to clean them up and sit them in a mix.

Heft or lack of heft (or slam, or whatever) is not about elite-ism, it's more about appropriateness and balancing the different needs for improved compromises that result in a better end product.

welp there goes Agedhorse with his facts and wisdom again.....

 

[silky smoove]

An 88 key piano goes from 27.5 to 4,186.0 Hz. I can hear all of the keys.

Of course you can hear all the keys. That said, you almost certainly can't hear 27.5hz unless you're a small child as people's hearing degrades at the extreme ends rather rapidly simply by aging. The frequencies you've listed are the fundamentals. The overtones are what you tend to hear down at the low end of a piano.

 

[Short4since64]

New to TB and retired EE. Cannot see any difference between tube, solid state AB and class D so far as the amplifying technology is concerned. The difference is in the power supply. Lead sleds use a "brute force" power supply with those huge "beer can" filter capacitors to filter the 120Hz pulsating DC to clean DC. Light weight SMPS power supplies are running at 30000 Hz or so and can use very small capacitors. Capacitors store energy.
Amplifier power is measured typically at 100% into full rated load, thus a transformer powered amp is measured with the supply voltage "sagged" to it's full load value, the SMPS powered amp's power supply is feedback regulated and doesn't rise or sag.
I have a Rane MA6, a professional multichannel amp that runs our wedges, on the bench to change the fan right now. Design similar to most AB amps. From the mfr's specs,150W RMS into 4 ohms, 6 separate channels, all channels driven. With full load, the supply rails are +-44 volts. With no signal, the rails rise to 63. Let's do the math. 44 squared X .707 X 50% (typical AB efficiency) /4=171 watts. Close to spec. Between notes the power supply recovers. Now at 63 volts - the voltage present during silence, 63 squared X .707 X 50% /4=350 watts. The stored energy in those massive capacitors is able to maintain that voltage for an 8th note or so before the voltage sags down. Thus that initial note, the one that slams, has a lot more available power behind it. Called transient power, a design shortcoming that just sounds great, just as the design flaws in the circuits copied and used used in most tube guitar amps created the defining sound of lead guitar.
In my younger, mentally diseased LOUD LOUD days, I was running two JBL double scoops off a Crest 8001, roughly 2400 watts RMS (off the 220 line that bands needed to run the 1000W par can lighting) Huge filter capacitors in that amp, still have and use one channel of it with smaller cabs (the other channel powers the low end of the PA). Could match the 100W Marshall stack the guitarist was using and louder It didn't slam, it punched you in the stomach!

 

[Joebone]

So I'm no tech guy, but earlier noted that the Trickfish Bullhead 1K apparently has a Pascal Class D module that has been supplemented with additional capacitors - and it's the most slammin' Class D amp I've ever played through (albeit on the clean side). Thoughts?

 

[silky smoove]

So I'm no tech guy, but earlier noted that the Trickfish Bullhead 1K apparently has a Pascal Class D module that has been supplemented with additional capacitors - and it's the most slammin' Class D amp I've ever played through (albeit on the clean side). Thoughts?

The sneaky thing about the B1K is its subtle top end roll-off. It’s a wonderful amp, and has been my main amp for a few years now. I think the way it rolls off up top makes it sounds bigger and fatter without the low end being all bloated. That, to me, is the biggest distinguishing factor between it and other amps that I would consider peers which I owned at the same time. I did an analysis of the top end roll-off I’m describing in the main Trickfish thread if you want to see the graphs and my long-winded write-up.

 

[agedhorse]

New to TB and retired EE. Cannot see any difference between tube, solid state AB and class D so far as the amplifying technology is concerned. The difference is in the power supply. Lead sleds use a "brute force" power supply with those huge "beer can" filter capacitors to filter the 120Hz pulsating DC to clean DC. Light weight SMPS power supplies are running at 30000 Hz or so and can use very small capacitors. Capacitors store energy.
Amplifier power is measured typically at 100% into full rated load, thus a transformer powered amp is measured with the supply voltage "sagged" to it's full load value, the SMPS powered amp's power supply is feedback regulated and doesn't rise or sag.
I have a Rane MA6, a professional multichannel amp that runs our wedges, on the bench to change the fan right now. Design similar to most AB amps. From the mfr's specs,150W RMS into 4 ohms, 6 separate channels, all channels driven. With full load, the supply rails are +-44 volts. With no signal, the rails rise to 63. Let's do the math. 44 squared X .707 X 50% (typical AB efficiency) /4=171 watts. Close to spec. Between notes the power supply recovers. Now at 63 volts - the voltage present during silence, 63 squared X .707 X 50% /4=350 watts. The stored energy in those massive capacitors is able to maintain that voltage for an 8th note or so before the voltage sags down. Thus that initial note, the one that slams, has a lot more available power behind it. Called transient power, a design shortcoming that just sounds great, just as the design flaws in the circuits copied and used used in most tube guitar amps created the defining sound of lead guitar.
In my younger, mentally diseased LOUD LOUD days, I was running two JBL double scoops off a Crest 8001, roughly 2400 watts RMS (off the 220 line that bands needed to run the 1000W par can lighting) Huge filter capacitors in that amp, still have and use one channel of it with smaller cabs (the other channel powers the low end of the PA). Could match the 100W Marshall stack the guitarist was using and louder It didn't slam, it punched you in the stomach!

Except that many SMPS in class D amps are unregulated and behave EXACTLY the same as unregulated line frequency power supplies but often with better performance. Some are regulated (including the ones that I typically use in this era) which does not have the inherent sag and deliver the same power even if the line voltage drops (something that line frequency supplies can't do).

What you are missing about SMPS is that more energy is stored in a lower value cap at the input of the switches because energy is a function of the square of the voltage, and with the bulk rail operating at ~350V, it doesn't take a lot of uF to store a LOT of energy. On the output the impedance of the switches is very low so the charge currents to the secondary caps is high. In the case of the SMPS I use, the secondary caps recharge about 200,000 times per second, so that voltage and current remain extremely robust. The caps HAVE to be large on a line frequency supply because the voltages are lower and they are only recharged 50-60 times per second and have to keep ripple under control or things become "noisy".

IMO, you are attributing an effect to something that is not really accurate. The "burst power" is defined typically as 20msec, which is about 1 cycle at 50Hz and it's rapidly depleted. There used to be a lot of marketing behind this concept, but it has more or less dissipated because there are things much more impactful in the bigger picture. That's my opinion as a (commercial) power amp designer of more than 40 years.

 

[LowEndOperative]

One more vote for the Peavey Headliner 1000. Don’t know why I ever got rid of mine.

 

[Nebadon2000]

Except that many SMPS in class D amps are unregulated and behave EXACTLY the same as unregulated line frequency power supplies but often with better performance. Some are regulated (including the ones that I typically use in this era) which does not have the inherent sag and deliver the same power even if the line voltage drops (something that line frequency supplies can't do).

What you are missing about SMPS is that more energy is stored in a lower value cap at the input of the switches because energy is a function of the square of the voltage, and with the bulk rail operating at ~350V, it doesn't take a lot of uF to store a LOT of energy. On the output the impedance of the switches is very low so the charge currents to the secondary caps is high. In the case of the SMPS I use, the secondary caps recharge about 200,000 times per second, so that voltage and current remain extremely robust. The caps HAVE to be large on a line frequency supply because the voltages are lower and they are only recharged 50-60 times per second and have to keep ripple under control or things become "noisy".

IMO, you are attributing an effect to something that is not really accurate. The "burst power" is defined typically as 20msec, which is about 1 cycle at 50Hz and it's rapidly depleted. There used to be a lot of marketing behind this concept, but it has more or less dissipated because there are things much more impactful in the bigger picture. That's my opinion as a (commercial) power amp designer of more than 40 years.

I don't understand most if any of this post; but someone who has put in the time/effort and passion to learn and understand his craft and not only how it works in general from all tech sides but how it relates to real world; And has put this Debate in the 'perspective of Reality' multiple times over the years but always recommends to the 'I JUST KNOW' crowd to use what makes them happy

Has a lot to do with why my Mesa WD 800 sounds great to me in all areas including the indescribable term 'Musicality'[most important]

 

[Short4since64]

Except that many SMPS in class D amps are unregulated and behave EXACTLY the same as unregulated line frequency power supplies but often with better performance. Some are regulated (including the ones that I typically use in this era) which does not have the inherent sag and deliver the same power even if the line voltage drops (something that line frequency supplies can't do).

What you are missing about SMPS is that more energy is stored in a lower value cap at the input of the switches because energy is a function of the square of the voltage, and with the bulk rail operating at ~350V, it doesn't take a lot of uF to store a LOT of energy. On the output the impedance of the switches is very low so the charge currents to the secondary caps is high. In the case of the SMPS I use, the secondary caps recharge about 200,000 times per second, so that voltage and current remain extremely robust. The caps HAVE to be large on a line frequency supply because the voltages are lower and they are only recharged 50-60 times per second and have to keep ripple under control or things become "noisy".

IMO, you are attributing an effect to something that is not really accurate. The "burst power" is defined typically as 20msec, which is about 1 cycle at 50Hz and it's rapidly depleted. There used to be a lot of marketing behind this concept, but it has more or less dissipated because there are things much more impactful in the bigger picture. That's my opinion as a (commercial) power amp designer of more than 40 years.

Very good point. Most SMPS I have encountered have an optocoupler circuit for feedback regulation of the output voltage. Any "surge power" as I referenced would only matter if the amplifier is being operated close to it's design power output, with the 2400 watt monstrosity I referenced, nowhere near that power was being used as my 4 JBL 2225s were only rated 200W each and I used a compressor set as a brickwall limiter to protect the speakers. The stomach punch in that case came from the 30ms or so it took for the limiter to drop the gain, but it sure felt good! High power, high speaker efficiency, rear loaded horn coupling, standing in the slip stream.
BTW my experience in musical electronics design has been building "boutique" tube guitar amps, and if you had a part in designing the Mesa F50, kudos! Our guitarist has one, excellent.

 

[edervjo]

It is interesting reading these posts, many are relating the same experiences I have had using various class D rigs. It's not just me!
I am a super-lead sled owner, (Crest CA9 2x900w slave with a SansAmp RPM and 2x15 eq. 4 space rack, 65lbs.)
Anything below 1200w classD just falls flat compared to just 1 channel of my sled, even using the same preamp and speakers for consistency. We play at a strong drumset level.
What i have noticed is a lack of specifics as to power ratings, my Crest does 900w @.01% thd, I read an Ampeg spec of 1000w@ 10%. Many just say "800 watts" , but with no reference. I think that is where many players get confused as to why any one rig lacks the delivery they expect over another. I run big power for the headroom, lower volumes that float you in an ocean of warmth, yet can respond with crisp solid details, which never compete for wattage articulate themselves from your fingers.
Total control over the movement of the speaker. But then, i am an artist, not an engineer, my interpretation of the physics involved, the details of what circuitry yields what tone is probably miles off from reality. But I do know results, and so far nothing makes my ears smile the same way,.... yet. Thus i schlepp the weight.

I am have been looking to lighten my load with a high powered ClassD head, as opposed to another rack amp, at least for some smaller gigs. You guys have provided some great insights, we are all chasing the same thing, regardless of what you might call it.

 

[agedhorse]

Very good point. Most SMPS I have encountered have an optocoupler circuit for feedback regulation of the output voltage. Any "surge power" as I referenced would only matter if the amplifier is being operated close to it's design power output, with the 2400 watt monstrosity I referenced, nowhere near that power was being used as my 4 JBL 2225s were only rated 200W each and I used a compressor set as a brickwall limiter to protect the speakers. The stomach punch in that case came from the 30ms or so it took for the limiter to drop the gain, but it sure felt good! High power, high speaker efficiency, rear loaded horn coupling, standing in the slip stream.
BTW my experience in musical electronics design has been building "boutique" tube guitar amps, and if you had a part in designing the Mesa F50, kudos! Our guitarist has one, excellent.

30mSec at low frequencies isn't going to be an audible feed-through but in reality what may be specified at 30mSec may in fact be over 100mSec because at low frequencies you need more than 1 or 2 cycles for the detector to work to generate a control voltage. In the digital realm, look ahead limiting changes the PERCEPTION of the attack by delaying the signal to allow for the control voltage to be generated and applied.

Many SMPS circuits do not feed back and regulate, mainly because it's very difficult to do for fast transient dynamic loads like a class D amp. Stability criteria are important here when that loop is closed, newer PWM controllers are more sophisticated but still the amp and SMPS need to be designed together as a system to maximize regulated performance.

It is interesting reading these posts, many are relating the same experiences I have had using various class D rigs. It's not just me!
I am a super-lead sled owner, (Crest CA9 2x900w slave with a SansAmp RPM and 2x15 eq. 4 space rack, 65lbs.)
Anything below 1200w classD just falls flat compared to just 1 channel of my sled, even using the same preamp and speakers for consistency. We play at a strong drumset level.
What i have noticed is a lack of specifics as to power ratings, my Crest does 900w @.01% thd, I read an Ampeg spec of 1000w@ 10%. Many just say "800 watts" , but with no reference. I think that is where many players get confused as to why any one rig lacks the delivery they expect over another. I run big power for the headroom, lower volumes that float you in an ocean of warmth, yet can respond with crisp solid details, which never compete for wattage articulate themselves from your fingers.
Total control over the movement of the speaker. But then, i am an artist, not an engineer, my interpretation of the physics involved, the details of what circuitry yields what tone is probably miles off from reality. But I do know results, and so far nothing makes my ears smile the same way,.... yet. Thus i schlepp the weight.

I am have been looking to lighten my load with a high powered ClassD head, as opposed to another rack amp, at least for some smaller gigs. You guys have provided some great insights, we are all chasing the same thing, regardless of what you might call it.

In reality, most bass players can't really identify 10% THD on a bass signal which is why that's become more of the norm for MI amps. The reason for this is because a bass signal already consists of the fundamental plus a slew of harmonics which would be measured as THD of the fundamental, so separating out the bass's harmonics from the THD harmonics is more or less "impossible" (or very, very difficult)

 

[Short4since64]

It is interesting reading these posts, many are relating the same experiences I have had using various class D rigs. It's not just me!
I am a super-lead sled owner, (Crest CA9 2x900w slave with a SansAmp RPM and 2x15 eq. 4 space rack, 65lbs.)
Anything below 1200w classD just falls flat compared to just 1 channel of my sled, even using the same preamp and speakers for consistency. We play at a strong drumset level.
What i have noticed is a lack of specifics as to power ratings, my Crest does 900w @.01% thd, I read an Ampeg spec of 1000w@ 10%. Many just say "800 watts" , but with no reference. I think that is where many players get confused as to why any one rig lacks the delivery they expect over another. I run big power for the headroom, lower volumes that float you in an ocean of warmth, yet can respond with crisp solid details, which never compete for wattage articulate themselves from your fingers.
Total control over the movement of the speaker. But then, i am an artist, not an engineer, my interpretation of the physics involved, the details of what circuitry yields what tone is probably miles off from reality. But I do know results, and so far nothing makes my ears smile the same way,.... yet. Thus i schlepp the weight.

I am have been looking to lighten my load with a high powered ClassD head, as opposed to another rack amp, at least for some smaller gigs. You guys have provided some great insights, we are all chasing the same thing, regardless of what you might call it.

Crest amps are amazing, they have been the go-to brand for touring sound for years. I do the same thing using only 1 channel, the other is used for the PA. As for distortion specs, 10% is high but subtract 2 or 3% from the spec'd wattage and it'll be clean at that level. And 2nd harmonic is often desirable - it's on key 1 octave up. The "cold clipper" stage of the venerable Marshall JCM800, Soldano amps and all the copies and clones is designed to do just that. In the 60's, recording studios rented intentional harmonic distortion by the minute (Aphex Aural Exciter). You hit it right on the nose about speaker control, big linear amps present almost a dead short to the back EMF from the speaker.
65# is nothing. I also play keys, try buggy-lugging a Hammond B-3 without the 3 R's (roadies, ramps and Ryder), another sound that CANNOT be digitally duplicated. Close, but no banana. Keep your sled, good choice of gear, I have a Crest 8001 and a mono 31 band eq, even heavier, just never breaks, and nothing sounds like one. Enjoy the stomach punch.

 

[agedhorse]

Just for full disclosure, I worked for the company that originally started Crest Audio back in the very early 1980's, before the Crest brand name was established. The company was called Dallas Music Industries, and the first Crest power amp was for a Kelsey product called the PowerMix. This evolved into the Crest P-3501 which was the same as some FA series.

 

[seamonkey]

• The placebo effect. People who know that they are listening to a Class AB or Class D amplifier may be more likely to hear a difference between the two, even if there is no real difference.

 

[Joebone]

Hmm...essence of placebo is not knowing whether you are getting the real, or getting Memorex. But yes, non-aural cues can influence perception of outcome.