Class D amps sound inferior?

[alotabass]

To carry on my criticism of not understanding technology and drawing incorrect conclusions, Carver never offered a class D amplifier, therefore your amp couldn’t possibly be class D. In fact, the Carver amps were either class AB or class G/H (depending on rated output), exactly the same as the Crest CA amplifiers.

The difference is that the Carver used a phase controlled line frequency power supply which shrank it’s size.

First since the Carver was lightweight so I assumed it was Class D. I don't know enough about the electronics to speak at a high level about them but one thing is for sure and that is what my ears heard. You say that Carver and Crest are the same. Not to my ears. The Crest CA9 was superior in every way. The Carver was just ok and mushy on the bottom end. Crest was like a Brick wall on the lowend. It will kill you. Hahaha.

 

[agedhorse]

First since the Carver was lightweight so I assumed it was Class D. I don't know enough about the electronics to speak at a high level about them but one thing is for sure and that is what my ears heard. You say that Carver and Crest are the same. Not to my ears. The Crest CA9 was superior in every way. The Carver was just ok and mushy on the bottom end. Crest was like a Brick wall on the lowend. It will kill you. Hahaha.

No, I said that the Crest and Carver used the same class of power amp (NEITHER are class D). You claimed that the Carver was class D and attributed it's lack of bottom end to it being class D which is not correct.

The difference is that the Carver used a different type of power supply (not SMPS but a unique proportionally phase controlled line frequency supply).

With regard to the amp differences, there are some circuitry differences specific to the CA series (specifically the CA6 and CA9) that create the impression of more robust low end. This was a design decision by the lead designer (who I knew) and was an interesting enhancement, though it fell out of favor for some reason and I believe only those two models were like this. I don't recall the pro series doing this (the 4001/8002).

 

[Jeff Scott]

How does Carver's magnetic field amplifier fit into all of this?

 

[tshapiro]

I've played class D amps which include recent versions of by Fender, MarkBass, Ampeg, Mesa and a few others. Unfortunately I'm more of a bass player and less of an electrical engineer so I can't hang with some of the spec talk you guys throw around. But to me, the Class A/B Hartke LH1000 sounds more substantial and thunderous than the Class D's (most of them 800 watts). I did just recently add some 2000 watt Class D subwoofers to my PA and they also sound thunderous. So, I can't explain why I hear that visceral rumble from the Class D subs but not the Class D bass amps. All that being said, it is a pain to carry the heavier LH1000 so if anyone falls in love with a Class D bass amp than by all means they should use it. I just haven't found one for me yet.

 

[Jim C]

IME, it depends very much on the harmonic distribution. On the average, 5% is a reasonable threshold of audibility for the average player and good listening conditions. Many players can't hear 10% under average conditions though.

Can you say more about harmonic distribution?
Are you talking about odd vs even or something else.

One other comment about 5% audible distortion is that I'm making the assumption that it is 1 player with a bass sitting in front of an amp. I think when you add the rest of the band and room acoustics, the chance of hearing distortion drops dramatically.

 

[BlueTalon]

Class D for me, thank you very much!

I don't know what class anything is, but I don't care. I liked my Sunn Coliseum a lot back in the day*, but if I can get the same or more power out of a box that's 1/4 the weight and size, with more tone and convenience options, that's not a hard choice.

*More recently I had a SWR SM400 and a Hartke 2500, and neither one of them were worth the hassle of hauling them around to gigs. I mention them only because I think they were probably not class D amps, and I only think that because of the weight.

 

[mmon77]

Regardless of what anyone thinks about Class D bass amps, just remember this. If you've gone to any professionally produced live show in probably the last 10 years, it's an almost 99% chance that everything you heard came through Class D amps over the PA. So you can hate on Class D all you want, but it isn't going away, and unless you're playing without PA support, chances are you're going to go through Class D anyway.

Only a production company run by sadists would lug around racks of lead sleds these days.

 

[byacey]

Only a production company run by sadists would lug around racks of lead sleds these days.

It's part of the employee's physical fitness benefits program.

 

[byacey]

How does Carver's magnetic field amplifier fit into all of this?

The magnetic field thing is just marketing BS. They lightened up the amp *somewhat* by making the transformer core slightly smaller and phase controlling the AC line voltage into the transformer according to the power demands of the amp. These were used on the PM 1.5, PM 1200, PT1800 and PT2400 amps. The pm 2.0 and PT1250 were essentially a PM1200, but used a crude HF switching supply which lightened up the amp considerably.

Strangely though, I've seen some of their hifi consumer amps labeled with the magnetic field propaganda even though it was a conventional transformer power supply.

 

[agedhorse]

How does Carver's magnetic field amplifier fit into all of this?

Earlier claim suggested that Carver was class D (it’s not)

Can you say more about harmonic distribution?
Are you talking about odd vs even or something else.

One other comment about 5% audible distortion is that I'm making the assumption that it is 1 player with a bass sitting in front of an amp. I think when you add the rest of the band and room acoustics, the chance of hearing distortion drops dramatically.

Both even/odd order and the distribution of lower to higher order. Both of these variables can be controlled in part by design.

Yes, adding the rest of the band, especially guitars and drums, can seriously mask the distortion to where even 10% THD is inaudible.

The magnetic field thing is just marketing BS. They lightened up the amp *somewhat* by making the transformer core slightly smaller and phase controlling the AC line voltage into the transformer according to the power demands of the amp. These were used on the PM 1.5, PM 1200, PT1800 and PT2400 amps. The pm 2.0 and PT1250 were essentially a PM1200, but used a crude HF switching supply which lightened up the amp considerably.

Strangely though, I've seen some of their hifi consumer amps labeled with the magnetic field propaganda even though it was a conventional transformer power supply.

I don’t remember the switching supplies, we’re those post Carver and in the Phoenix Gold days?

 

[byacey]

Earlier claim suggested that Carver was class D (it’s not)



Both even/odd order and the distribution of lower to higher order. Both of these variables can be controlled in part by design.

Yes, adding the rest of the band, especially guitars and drums, can seriously mask the distortion to where even 10% THD is inaudible.



I don’t remember the switching supplies, we’re those post Carver and in the Phoenix Gold days?

No, I think they were still part of the original Carver corporation; probably some of the last amps they developed before Phoenix took over. They boasted monocoque construction for the chassis too, but the screws would constantly loosen up, as they were self tap into aluminum.

Edit: I looked it up, and it appears it was a Pheonix Gold product. My memory must be slipping.

 

[agedhorse]

No, I think they were still part of the original Carver corporation; probably some of the last amps they developed before Phoenix took over. They boasted monocoque construction for the chassis too, but the screws would constantly loosen up, as they were self tap into aluminum.

Edit: I looked it up, and it appears it was a Pheonix Gold product. My memory must be slipping.

Some days I wonder if I even have a memory!

 

[808State]

The Carvers were rail switchers, or Class G

 

[agedhorse]

The Carvers were rail switchers, or Class G

Some were class AB, some were class G/H and some were an odd hybrid with the first tier class AB, the second tier class G and the third tier class H.

 

[808State]

Its interesting to look at previous attempts to improve amplifier efficiency.
Then again just having fun and making amplifiers.
Class G/H just never was a very fun topology to design.

I give credit to the people that have done it.
Maybe even taking the risk to market such a thing.
Pretty crazy

 

[alotabass]

No, I said that the Crest and Carver used the same class of power amp (NEITHER are class D). You claimed that the Carver was class D and attributed it's lack of bottom end to it being class D which is not correct.

The difference is that the Carver used a different type of power supply (not SMPS but a unique proportionally phase controlled line frequency supply).

With regard to the amp differences, there are some circuitry differences specific to the CA series (specifically the CA6 and CA9) that create the impression of more robust low end. This was a design decision by the lead designer (who I knew) and was an interesting enhancement, though it fell out of favor for some reason and I believe only those two models were like this. I don't recall the pro series doing this (the 4001/8002).

Back in the day I bought a Contrabass Servo-drive Subwoofer (I still own). I was powering it with the Carver. The Carver would get so hot to the touch it could burn you. I was impressed the Carver never blew up. Then I spoke to the designer of the Sub and he recommended Crown or Crest power-amps. He said since the sub is motor driven it needs an amp stable to 2 ohms or less and not many power amps fit that bill at the time. When I bought the Crest the sound difference was night and day. Not only that but the Crest never got hot or broke a sweat. The Subwoofer engineer said it was all about the power supply and he didn't recommend using power-amps with switching power supplies. Again I wont pretend to know what he is talking about. All I can tell you is the audio quality was night and day.

 

[Jeff Scott]

The magnetic field thing is just marketing BS. They lightened up the amp *somewhat* by making the transformer core slightly smaller and phase controlling the AC line voltage into the transformer according to the power demands of the amp. These were used on the PM 1.5, PM 1200, PT1800 and PT2400 amps. The pm 2.0 and PT1250 were essentially a PM1200, but used a crude HF switching supply which lightened up the amp considerably.

Strangely though, I've seen some of their hifi consumer amps labeled with the magnetic field propaganda even though it was a conventional transformer power supply.

Earlier claim suggested that Carver was class D (it’s not)

I knew the Carver wasn't Class D, (I don't recall any claims on their part to such) just Bob's mumbo jumbo about his latest/greatest design concept. I had a M500T for a few days back in the late '80s to try out, but "ripped" it out of my stereo system as I found it to be rather harsh sounding. Certainly, not musical sounding, IME.

I even gave one of his preamp's a try, a C2, but it, too, didn't last long in my system, being replaced with a GAS Thalia.

Some days I wonder if I even have a memory!

Age catches up to all of us, eventually!

 

[Passinwind]

Some days I wonder if I even have a memory!

And you are...?

 

[Lync]

What do we do when we get to "Class Z"? Does the world end?

 

[Jeff Scott]

What do we do when we get to "Class Z"? Does the world end?

We just kick back on the front porch, playing our acoustic guitars.