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Class D Amps
- Thread starter jazztonebass
- Start date
I'd argue it isn't that they compress and start to distort earlier - it's that they sound worse at the same levels of compression and distortion.
yeah, kind-of.....
There are problems with clipping of Class-D that do not exist with analog amps.... the degree to which that is a problem depends on the design of the class-D, as well as how that design is implemented.....
- Mar 8, 2011
- 12,232
- 51,187
- Disclosures
- Authorized greenboy designs builder/Owner of BNA Audio
I think it's a combination of both, although I would argue using the term "worse." There's something about it that reminds me of a tube being run clean but being pushed just a little too hard. More of a 2d version of it compared to tubes, but I hear it.
Dudes.......... Don't use "tubes" as a reference.......... better name an amp.....
If you had messed with any tube amps as outright lousy as ones I have sometimes seen, you'd begin to see that it's possible to build a tube amp that makes even a crude SS amp sound good.....
I recall one from either Japan or Korea... don't know... gene Kornblum brought it back from somewhere.....it was a guitar amp allegedly, all tube, and had a name something like "The Bulb", or some such nonsense... the outline of a tube was part of the logo, which is the connection there, bulb...tube..whatever.
It was the worst..... overdrive sounded something like a riveting gun, I kid you not.... I didn't know it was possible to make an amp that sounded that bad overdriven. I surely learned something from that unit....
But it was "ok" below clipping.... nothing special, but "ok".
Even tubes can sound like crap......
If you had messed with any tube amps as outright lousy as ones I have sometimes seen, you'd begin to see that it's possible to build a tube amp that makes even a crude SS amp sound good.....
I recall one from either Japan or Korea... don't know... gene Kornblum brought it back from somewhere.....it was a guitar amp allegedly, all tube, and had a name something like "The Bulb", or some such nonsense... the outline of a tube was part of the logo, which is the connection there, bulb...tube..whatever.
It was the worst..... overdrive sounded something like a riveting gun, I kid you not.... I didn't know it was possible to make an amp that sounded that bad overdriven. I surely learned something from that unit....
But it was "ok" below clipping.... nothing special, but "ok".
Even tubes can sound like crap......
First reply and as astute an answer as there is to what is fast becoming a virul urban myth/spam.
I was kind of assuming we were talking about good onesDudes.......... Don't use "tubes" as a reference.......... better name an amp.....
If you had messed with any tube amps as outright lousy as ones I have sometimes seen, you'd begin to see that it's possible to build a tube amp that makes even a crude SS amp sound good.....
I recall one from either Japan or Korea... don't know... gene Kornblum brought it back from somewhere.....it was a guitar amp allegedly, all tube, and had a name something like "The Bulb", or some such nonsense... the outline of a tube was part of the logo, which is the connection there, bulb...tube..whatever.
It was the worst..... overdrive sounded something like a riveting gun, I kid you not.... I didn't know it was possible to make an amp that sounded that bad overdriven. I surely learned something from that unit....
But it was "ok" below clipping.... nothing special, but "ok".
Even tubes can sound like crap......
but good point. I'll tell you though...I can't remember ever playing through a truly bad one. Some I liked more than others, but I thought they were all cool. Then again, I've lived a much more sheltered life than you when it comes to amps.
Like the title said... IT IS ALL IN THE DESIGN... I can design a piss poor AB amp, I can design a great AB amp. I can design a class D amp. Very few people in any of these threads understand what any of these (A, B, AB, D) mean so it just infuriates my EE mind. Hell few EE's actually know what class D amplification is, including the professors I had "that has something to do with PWM right?"
Yes...
I don't pretend to know anything about engineering...all I know is what I hear. And if it's all in the design, then you'd think someone else can make an amp without tubes, a big iron power transformer, and a big iron output transformer that sounds in every way like an SVT. I just don't see how it's possible that the power amp topology doesn't enter into it, and quite frankly, from what Andy and Jerrold are saying (and if any people on here are qualified to speak about it, it's them), I'm still not convinced.
OTOH, it's probably very easy to check out for people who have two high quality power amps, one with iron PS, one with SMPS. I'm not one of them, but I'm surprised that people who can do the comparison themselves haven't checked in. Certainly there are folks on here with one of each power amp that could give some insight.
OTOH, it's probably very easy to check out for people who have two high quality power amps, one with iron PS, one with SMPS. I'm not one of them, but I'm surprised that people who can do the comparison themselves haven't checked in. Certainly there are folks on here with one of each power amp that could give some insight.
I can express my opinion about these three various technologies, when I shall receive the class D amplifier Minnie 800D ( by James Demeter ).
The comparison will be Alessandro Basset Hound ( all tube / 100 watts with 2 X KT 120 Tung Sol ) versus Monique preamp + Fender MB1200 ( class AB ) or Minnie ( both amps = 800 Watts / 4 Ohm ).
During the bench test, all these amplifiers will be used through the Barefaced 69er cab (6X10" sealed ).
The comparison will be Alessandro Basset Hound ( all tube / 100 watts with 2 X KT 120 Tung Sol ) versus Monique preamp + Fender MB1200 ( class AB ) or Minnie ( both amps = 800 Watts / 4 Ohm ).
During the bench test, all these amplifiers will be used through the Barefaced 69er cab (6X10" sealed ).
On your point one, all amps sound different due to hundreds of things. It is why various all tube amps all sound quite different from each other
This is, IMO, where 'myths' continue to be supported. No other amp sounds like a Thunderfunk, no other amp sounds like an SVT, no other amp sounds like an LMII, no other amp sounds like a Shuttle 9, no other amp sounds like a DB750, no other amp sounds like an Orange200, no other amp sounds like a Hiwatt, no other amp sounds like a TH500, etc., etc., etc. Again, better to not really think about topology as a driver of amp purchase choice (unless again you really like to push power tubes into overdrive, which is a unique aspect of tubes as far as I know).And, the second comparisons have been done, and when done by engineers (especially like Bob Lee, from firms who make both designs) there is no difference IF gain matched (which is hard to do).
Edit: And per the very good post below, another thing that makes your argument a little problematic is that you assume, because you dig an SVT, that somehow that is the 'target' that other amp makers use as the 'gold standard'. This is in no way the case. Your like of the SVT is, of course, totally valid, but is your preference. I would personally have NO interest in trying to find an amp that sounds like an SVT. It would be like saying 'why can't other amp makers make an amp that sounds like a Thunderfunk'. Why would another amp maker do that. Or a Walter Woods, or an LMII or whatever. Makes no sense.
This will tell you very little, since the 'effects return' that you use are all very different (i.e., most are not a 'direct into the power amp'). This is as situation of 'bad data is worse than no data at all', since you will hear a difference, and attribute it to power amp design, when most likely it is driven by what is after the effects loop, the hi passing and other circuitry used to voice the amps, and different gain levels of the effects return.
Combine that with the fact that you are even using different pre's between the Basst Hound and the other amps, and well, what you have is a simple comparison among three rigs, which is interesting in itself, but answers absolutely NOTHING about the power amps themselves, especially the topology impact of the power amps.
I am with Rockman and the other engineers on this..
To be correct here the topology would be the design of the amp ie class A, class AB, B or D, not the components used in the power stage, so the topology actually does not enter into it at all.
Neither does SMPS come into it as it is simply a power supply design choice, which can be used with any type of devices and any type of output topology.
What you are referring to is the use of tubes as an output stage, and for the same reason there are 1,000,000 posts in the SS vs Tube discussion, there are reasons why tubes sound different, specifically a soft limiting/compression/distorion at the near limits with the unique artifact of solely producing 2nd order harmonic content... it is that one single artifact that gives tubes that "louder" and "more musical" and "smooth breakup" and each and every other glowing term anyone desires.
There is no way, without additional circuitry, that any transistor, FET, MOSFET, PWM brick output circuit can behave in the identical non-linear manner.. However pre-emptively accessing the signal and deliberately introducing the same effects at the pre-amp stage using DSP and remain within the clean headroom of a SS amp and yes.. and power supply design with any output topology and output device pairings can be made to sound just like an SVT...
but why bother?.. it would be a fruitlessly pointless and expensive engineering exercise...and even if a new unit is cheaper, more powerful and identical sounding, the universe will cry.. "but its not an SVT" and any bassist that wants an SVT will go buy one regardless, and everyone else wont buy it cos they didnt want an SVT in the first place .,,hence it would be doomed to commercial failure.
To be correct here the topology would be the design of the amp ie class A, class AB, B or D, not the components used in the power stage, so the topology actually does not enter into it at all.
Neither does SMPS come into it as it is simply a power supply design choice, which can be used with any type of devices and any type of output topology.
What you are referring to is the use of tubes as an output stage, and for the same reason there are 1,000,000 posts in the SS vs Tube discussion, there are reasons why tubes sound different, specifically a soft limiting/compression/distorion at the near limits with the unique artifact of solely producing 2nd order harmonic content... it is that one single artifact that gives tubes that "louder" and "more musical" and "smooth breakup" and each and every other glowing term anyone desires.
There is no way, without additional circuitry, that any transistor, FET, MOSFET, PWM brick output circuit can behave in the identical non-linear manner.. However pre-emptively accessing the signal and deliberately introducing the same effects at the pre-amp stage using DSP and remain within the clean headroom of a SS amp and yes.. and power supply design with any output topology and output device pairings can be made to sound just like an SVT...
but why bother?.. it would be a fruitlessly pointless and expensive engineering exercise...and even if a new unit is cheaper, more powerful and identical sounding, the universe will cry.. "but its not an SVT" and any bassist that wants an SVT will go buy one regardless, and everyone else wont buy it cos they didnt want an SVT in the first place .,,hence it would be doomed to commercial failure.
Oops !!! I'm sorry . I forgot to specify that the Fender MB1200 is the mono power amp models. Monique will not be connected in loop effect but in the "preamp in" ( as MB1200 as Minnie 800D ).
On the other hand, you are right about the Basset Hound passive preamp. It is totally different of that of Monique.
Apparently, the real scientific comparison is very complicated to produce for us. The equipment which we have does not allow it.
My judgment(sentence) will not be objective in 100 %, and my preferences will concern only me and my ears ( in the professionalism of my musician's life).
P.S : I don't know if my thought is understandable for you. My English is so bad.
Oops !!! I'm sorry . I forgot to specify that the Fender MB1200 is the mono power amp models. Monique will not be connected in loop effect but in the "preamp in" ( as MB1200 as Minnie 800D ).
On the other hand, you are right about the Basset Hound passive preamp. It is totally different of that of Monique.
Apparently, the real scientific comparison is very complicated to produce for us. The equipment which we have does not allow it.
My judgment(sentence) will not be objective in 100 %, and my preferences will concern only me and my ears ( in the professionalism of my musician's life).
P.S : I don't know if my thought is understandable for you. My English is so bad.
Your English is wonderful! Yes, it gets complicated! You own some nice stuff !
Double blind test it to confirm "sound worst". And take some measurements so it's know the type and kind of compression and distortion that sounds better or worst.
If there was some magic compression that all players like, then you can add it before the amp. This would give magic compression at any level. If you don't like the kind of compression and amp allegedly gives, the a limiter and warning light can be used. Add more power to get above the point that the allegedly offensive compression would happen.
Amps in general aren't really the best at "effects". They are best used as just gain. The fringe case of the edge of pushing maximum level is not practical to always be concerned about.
Yep...
Heck, I HAVE designed both good AND piss poor implementations of A, AB, and B class power amplifiers... The couple swipes I've taken at class D I'd put completely in the piss poor department.
Thank you for a very clear and concise explanation.There was no sarcasm intended,sorry you took it that way,I just wanted to ask someone with more experience.Personally,I can't hear much of a difference,especially in a live situation.When I started playing every thing was heavy,so I'm loving all the new lightweight gear.
