Does class D have the Heft of SS

[DavesnothereCA]

....UPDATE : the product page for the SA450 [This invalid link has been removed] (link is on their discontinued page) makes no mention of the amp's class either.

Nor does the page for the LMII : [This invalid link has been removed] , though I got the owner's manual from there just now.

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However, Page 9 of the owner's manual for the LMII mentions that in their sibling COMBO amps of that time, all of the power amps are 'analog', all power supplies are 'custom designed digital', and the preamps are solid state.

Invalid Link Removed

On the now-hidden (I diddled the URL to reveal it) original product page for the LMIII : [This invalid link has been removed] , they state "The 500-watt Markbass power amp (Markbass Proprietary Technology) supplies impeccable bass frequency reproduction." (THEIR bolding, not mine)

And the LMIII owner's manual says less about any of the circuitry class designations than the OM for the LMII did.

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[aborgman]

Which one protects the cab by HPF implementation at which number of f3?

My B15 preamp has a HPF at 40Hz.

So all of the poweramps were getting a signal high passed at 40Hz.

 

[ThisBass]

My B15 preamp has a HPF at 40Hz.

So all of the poweramps were getting a signal high passed at 40Hz.

If at least one of your amplifiers in question adds an additional HPF to the signal path you'll get a different tonal feel

 

[quickfix]

I never really worried much whether I was using class D, A/B, or H. I always felt, for some reason, that the issue was about SMPS vs linear power supply. There's just something reassuring about large transformers and the resounding whoomp they create on the dance floor.

 

[agedhorse]

I always felt, for some reason, that the issue was about SMPS vs linear power supply. There's just something reassuring about large transformers and the resounding whoomp they create on the dance floor.

I spent a lot of time doing double-blind testing with SMPS and line frequency supplies that had virtually identical electrical performance and guess what? Not a single player was able to tell the difference playing identical bass amps using the different power supplies, and there were probably 15-20 good players testing this premise. The end result of the experiment was the Genz Benz NeoPak 3.5.

I can think of a dozen pro audio power amps that use SMPS that are well respected for delivering the goods as well, in fact I can't think of ANY amp these days that doesn't use an SMPS, including the top sub amps found on the biggest tours in the world where budget is not a big deal.

 

[quickfix]

I spent a lot of time doing double-blind testing with SMPS and line frequency supplies that had virtually identical electrical performance and guess what? Not a single player was able to tell the difference playing identical bass amps using the different power supplies, and there were probably 15-20 good players testing this premise. The end result of the experiment was the Genz Benz NeoPak 3.5.

I can think of a dozen pro audio power amps that use SMPS that are well respected for delivering the goods as well, in fact I can't think of ANY amp these days that doesn't use an SMPS, including the top sub amps found on the biggest tours in the world where budget is not a big deal.

Don't get me wrong. I like the sound my PF 800 produces in a smallish venue.
But when I want gut wrenching power I use the PF 800 as a preamp and run it through a Peavey PV2600 power amp for a resounding thump. Running the PF 800 preamp through that power amp using just one channel means it's still only capable of the same wattage as the PF 800 on its own. But the difference in feel is palpable. My band mates and club goers agree.

The downside of the Peavey power amp is that it's heavy. Otherwise I'd take it everywhere.
It does go to most gigs where my primary is the PF 800, but sits outside in the car as back up. I've also used it with my VT Bass DI (it's always in the guitar case) as the preamp.

 

[agedhorse]

Have you tried the Peavey IPR or the similar Crest series? You might be surprised.

 

[murphy]

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As you noticed, I got the manual from a 3rd party site, and they do not have the product page from the original site captured either.

Doncha just LOVE 'information scatter' ?!

A similar thing happened when I was looking up the Mesa Subway D800 head the other day. - The web site product page did not mention that the watts were RMS, nor the THD numbers at all, but the downloadable owner's manual (linked from the same page) had the full info.

At least in THAT case though, when the product page is eventually gone/orphaned, the owner's manual will be the more complete compilation, for the Mesa.

And I did not check about the LMII nor LMIII yet, as I got distracted.

UPDATE : the product page for the SA450 [This invalid link has been removed] (link is on their discontinued page) makes no mention of the amp's class either.

Nor does the page for the LMII : [This invalid link has been removed] , though I got the owner manual from there just now.
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I find it very strange that they have managed to remove all evidence of those earlier amps class AB status, when they were so proud advertising it at the time...on every spec sheet and product list online....weird....the F1 was their first class D offering at the time....or so they claimed when they came out

 

[murphy]

 

[DavesnothereCA]

I never really worried much whether I was using class D, A/B, or H. I always felt, for some reason, that the issue was about SMPS vs linear power supply. There's just something reassuring about large transformers and the resounding whoomp they create on the dance floor.

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I have not been in the position to have done the plethora of tests which Aged Horse and a few others here obviously have, but I was kind of wondering too about which factor mattered the most ? - the amp class, the power supply class, or what else might affect our perception of things, such as HPFs, EQ topology, volume control taper, etc.

And the average user does not consider most of those possible factors, instead just what he or she hears and feels when playing (or listening, if it is not the bass player commenting).
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[DavesnothereCA]

Have you tried the Peavey IPR or the similar Crest series? You might be surprised.

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Thanks for the tip.

And I had just recently noticed that PV now owns Crest, and apparently Trace Elliot, as per a logo on the PV web site seen only last night.
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[DavesnothereCA]

I find it very strange that they [MarkBass] have managed to remove all evidence of those earlier amps' class AB status, when they were so proud advertising it at the time...on every spec sheet and product list online....weird....the F1 was their first class D offering at the time....or so they claimed when they came out

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Funny how that sometimes goes.

Did you see my later post #621 ?

Also, in another post (in my RMS thread), I noted that Orange seems to have returned to Class AB1 in current s/s bass head offerings, after making an apparently successful Class D series of bass amps for a period.

On the website, they mention in passing that they have done so, but no explanation of WHY.

I do not recall the type of PS which each series has/had.
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[DavesnothereCA]

View attachment 2810491

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Purty !

I do like their colour scheme !

Likely easy to see on a darkened stage too.

And clearly you are a repeat customer, which in itself says a lot.

Is the top one a preamp, or what ?
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[chris_b]

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Is the top one a preamp, or what ?
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The top one is the F1.

The only Markbass amp I haven't liked. I had it at the same time as my LM2, which I liked a lot.

 

[murphy]

The top one is the F1.

The only Markbass amp I haven't liked. I had it at the same time as my LM2, which I liked a lot.

I did not like it either...first impression of class D

more sterile sounding...less warmth and booty

 

[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

This wasn't meant as a trick question but rather to educate myself and others as to how slew rate and damping factor affect MI amplifiers. It would also be great to explain how these measurements affect class AB vs. Class D amplifier performance.
Do big numbers matter?

As I understand it:
Slew rate is the rate of voltage change per unit of time
Damping factor is the amplifiers ability to control the overshoot of a loudspeaker

 

[agedhorse]

This wasn't meant as a trick question but rather to educate myself and others as to how slew rate and damping factor affect MI amplifiers. It would also be great to explain how these measurements affect class AB vs. Class D amplifier performance.
Do big numbers matter?

As I understand it:
Slew rate is the rate of voltage change per unit of time
Damping factor is the amplifiers ability to control the overshoot of a loudspeaker

It's actually a good question.

Slew rate is probably one of the most misunderstood specifications in the audio industry, especially as it applies to bass amplication.

Slew rate is the maximum rate of change of voltage, and it SEEMS on the surface that faster is better... until you understand how it applies to a real world signal AND the negative consequences that come along in the quest for bigger and bigger numbers.

In an audio signal, let's use a sine wave as an example, where does the maximum rate of change of voltage occur? No, not at the top and bottom of the waveform as many audiophile articles incorrectly state, but at the zero crossing point since taking the derivative of the sine voltage shows the max rate of change is at zero degrees or zero volts. This is based on simple trigonometry of a sine function.

The slew rate is typically expressed in volts per microsecond, and it has to be fast enough to reproduce the equivalent sine wave of the highest frequency of the highest desired harmonic at the level that the harmonic is present in the signal.

The required slew rate is defined by amplitude and frequency, for bass guitar amps that swing 100V the 10kHz component will always be less than 10V so doing the math (off the top of my head) will result in somewhere around 5V/uSec to satisfy both conditions.

Why not design an amp as fast as possible? Because many occur the techniques used to speed things up so fast detract from stability and can become detrimental when driving complex reactive loads, resulting in negative artifacts such as chirping, chattering, and even spontaneous combustion from oscillation.

The higher the frequency and the higher the amplitude, the higher the required slew rate. As long as the slew rate is higher than the minimum required (plus margin), there's no real benefit but plenty of potential for downside.

I will address damping factor later, as it is also highly misunderstood.

 

[tombowlus]

I remember now..
I only wish that you had them long enough to do a full rundown for BGM... IIRC , fender needed them returned before you could get the review completed.
Sort of a Thunderfunk on steroids and extended Lows and highs.. My fave feature is the ROOM BALANCE control.
I don't use 2Ω loads anymore like i used to. But It is rock solid at 2Ω even on hot summer outdoor gigs. at least my TB 1200 is.

Well, I had the TB1200 in for review (which we had to send back too early to test), but I own an 800 Pro.

 

[DavesnothereCA]

~
However, Page 9 of the owner's manual for the MarkBass LMII mentions that in their sibling COMBO amps of that time, all of the power amps are 'analog', all power supplies are 'custom designed digital', and the preamps are solid state.

Invalid Link Removed

On the now-hidden (I diddled the URL to reveal it) original product page for the LMIII : [This invalid link has been removed] , they state "The 500-watt Markbass power amp (Markbass Proprietary Technology) supplies impeccable bass frequency reproduction." (THEIR bolding, not mine)

And the LMIII owner's manual says less about any of the circuitry class designations than the OM for the LMII did.

~

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UPDATE :

Rereading the OM for the MarkBass SA450 and SD800 heads Invalid Link Removed , I just found something more on Page 4 in the overview paragraph :

It says that the 450 uses an analog power amp, and that the 800 instead uses a digital power amp.

(I am interpreting analog to mean Class AB, and digital to mean Class D.)

That goes some distance to explain how both heads can weigh the same, which I was wondering after my first skim of that manual, as well as the 'A' vs the 'D' in the two model numbers.

AND, in the overview paragraphs of the OM for the MarkBass F1 Invalid Link Removed , which also contains info on the LMII and the LMK, it says on Page 16 that the F1 has a digital power amp, and on Page 6, it says that the LMII has an analog power amp.

The Tech Details pages for all 3 units in that manual express all output wattages as RMS, including for the LMK which BTW is analog too.

However, the amp classes are not mentioned on the Tech Details pages for any of the examples mentioned in this post.

Weird, as that is exactly where I would have EXPECTED the info to be, if anywhere at all.
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[DavesnothereCA]

I did not like it [the MarkBass F1] either...first impression of class D

more sterile sounding...less warmth and booty

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Less.... (wait for it).... HEFTY ? ( He asked with a . )

BTW, your pic suggests that you still own all 3 heads, so you must still like each one, unless that is an old pic.
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