Good Class D amps ??

[mocenigo]

On 1/21/2019 at 12:37 AM, GeneZ said:

Why not cut to the chase? 

 

Someone ought to manufacture an amplifier and call it...   "The .00001 THD."

 

It would eventually gain the nickname...   "Are you Happy Now?  Amp."

 

The Neurochrome 686 amp gets quite close (0.00025%)

[Matias]

Hypex nCore NC1200 and NC2k are now available for OEMs. 👏

[GeneZ]

There are amps that designers add in even harmonics to produce a very nice "tube" effect on the sound. I have heard it.  It even sounds better than what I heard heard with tubes.  In essence, its the best of both worlds.

 

Because they do this?  The better sounding amp will not show as low distortion measurements.  Who wins? 

[Ralf11]

we need a good SET Class D amp with high bandwidth...

[mocenigo]

18 minutes ago, Ralf11 said:

we need a good SET Class D amp with high bandwidth...

 

Single Ended Triode? 😄

 

It is technically possible, I think. After all, a tube is an output device...

[mocenigo]

34 minutes ago, GeneZ said:

There are amps that designers add in even harmonics to produce a very nice "tube" effect on the sound. I have heard it.  It even sounds better than what I heard heard with tubes.  In essence, its the best of both worlds.

 

Because they do this?  The better sounding amp will not show as low distortion measurements.  Who wins? 

 

Well, FM Acoustics pre-amplifiers add a tad of 2nd harmonic to just the mids. Among the most transparent gear in the world, not the most neutral, very nice sound. 

 

 Roberto

[mocenigo]

11 hours ago, Matias said:

Hypex nCore NC1200 and NC2k are now available for OEMs. 👏

 

I thought the NC1200 was already available to OEMs

[GeneZ]

1 hour ago, mocenigo said:

 

Well, FM Acoustics pre-amplifiers add a tad of 2nd harmonic to just the mids. Among the most transparent gear in the world, not the most neutral, very nice sound. 

 

 Roberto

  Ahh!  Another good company to be aware of. Thank you.

 

I just noticed that the Resolution Series 255-MKII uses the same type of potentiometer  as found in my passive preamp. 

https://image.jimcdn.com/app/cms/image/transf/none/path/sb99076bb5e16690c/image/ie536af55798bec26/version/1391575986/meticulous-attention-and-precision-in-every-detail-is-one-reason-for-unique-results.jpg

 

I gain the second harmonics with my NuPrime ST-10.  Very tube like in a very satisfying way, especially when its obviously sweet and detailed.

 

I also have a good tube preamp that sounds surprisingly almost identical with my passive.  Both use the same potentiometer. Very neutral tube preamp at that.

 

My passive preamp (when used in balanced mode) is the audiophile secret of the century.   I use only top notch balanced cables and sit back and laugh!  One balanced cable alone costs more than this unit!    Nob sound passive preamp

 

The NobSound will make your high-end system sound as good as the components you choose to implement. maybe I got an unusual piece?  Its so simple in its implementation.  Hefty metal casing.

 

I am now learning how power cords can greatly effect what is heard.

 

 

I may even place my tube preamp for sale in the near future and concentrate on finding the right power cords.  But, first.  I am going to test to see how different power cords will effect this nice triode preamp.

[GeneZ]

1 hour ago, Ralf11 said:

we need a good SET Class D amp with high bandwidth...

  

 

Could a tube possibly switch that fast with precision?  ...............   

 

 

 

[sandyk]

11 minutes ago, GeneZ said:

I may even place my tube preamp for sale in the near future and concentrate on finding the right power cords. 

 

Any Preamplifier or Power Amplifier that is sensitive to power cords is either poorly designed, or is using a power cable that is inadequate for the output power demands of the amplifier.

[Ralf11]

stick to Class D please - other things should be posted elsewhere

[sandyk]

2 minutes ago, GeneZ said:

Class D only you say?   Show some class for once.  Delete sandyk's too.

 

 So a high power Class D amplifier won't be affected by inadequately dimensioned power leads ?

 They usually have opamps at their Input too !

[esldude]

4 hours ago, Ralf11 said:

we need a good SET Class D amp with high bandwidth...

Spoken in the voice of John Wayne, "You think a gigahertz would do it, pilgrim?"

[esldude]

3 hours ago, GeneZ said:

  

 

Could a tube possibly switch that fast with precision?  ...............   

 

 

 

They use them in microwaves.  

[GeneZ]

4 hours ago, esldude said:

They use them in microwaves.  

  @ a  switching frequency to 600 KHz? 

[Matias]

17 hours ago, mocenigo said:

 

I thought the NC1200 was already available to OEMs

I think the NC1200 was available to a select few manufacturers and not even listed under OEM amplifiers on their website.

 

Also with ICEpower introducing their ICEedge 1200AS this could have made Hypex change their minds and add the NC1200 and the new NC2k available on OEM too for competition.

 

In a few months Nord, Apollon, Rouge and others could list them on their product lines.

 

All speculation on my side.

[bluesman]

19 hours ago, GeneZ said:

  Could a tube possibly switch that fast with precision?  ...............   

 

From a 2010 article in IEEE MicroWave Journal:

• "Vacuum electronics (VE) amplifiers and oscillators are used for military and commercial applications that require high power at high frequency and also used in scientific research areas such as high-energy particle accelerators and plasma heating for controlled thermonuclear fusion...The other common tube amplifiers used in high-power transmitters include three types of devices: helix and coupled-cavity types, microwave power modules (MPM), and klystrons."

One of my favorite amps of all time (and the one I most enjoyed building and most regret selling) was the HK CItation 2.  Nobody was a bigger proponent of high bandwidth than Stu Hegeman, and this was his masterpiece power amp (his C1 preamp was also a masterpiece). The input stage used a pair of 12BY7 video pentodes with a bandwidth of over a MHz.  He used to demo the C2 at shows by using it as a video amplifier! 

 

The sound quality was absolutely superb - it was every bit the equal of my current Prima Luna except for a bit of flabbiness in the deep bass and a slightly higher noise floor if the tubes weren't perfect.  I'd hope and expect that a tube switching amp designed by a mind like Hegeman's would sound great.

[GeneZ]

1 hour ago, bluesman said:

 

The sound quality was absolutely superb - it was every bit the equal of my current Prima Luna except for a bit of flabbiness in the deep bass.  I'd hope and expect that a tube switching amp designed by a mind like Hegeman's would sound great.

 That may be something to keep an eye out for.   I wonder what the problems may be in implementing it and bringing it to the market, other than the notion that tubes are not as readily available as they once were,  and need to be replaced.  How could such speed be maintained and know when its time to replace a tube? (typical question that will be asked)

 

When I was in the Army Signal Corps we were trained on tube radios...  But, I figured that was because we were back in the early 70's.  hmmmm.. 

[esldude]

12 hours ago, GeneZ said:

  @ a  switching frequency to 600 KHz? 

At higher frequencies than that.

 

Tubes aren't inherently low bandwidth. Transformers can be limited in bandwidth.

[GeneZ]

54 minutes ago, esldude said:

At higher frequencies than that.

  What kind of tubes would be needed in a class D amp?    Are these for output?  KT88's?  What are we talking about?  🧐

[bluesman]

29 minutes ago, esldude said:

Tubes aren't inherently low bandwidth. Transformers can be limited in bandwidth.

 

And the transformers in the HK CItation 2 were more than just special - the audio bandwidth of the output Xformers was 270+kHz. They've been pretty reliable in remaining C2s - most still work, with a little loving care.  There are some reports of open windings in power transformers, and there is at least one "fix" if you have the guts to open it and the luck to find the break at or near the surface. But there haven't been any new, NOS, or aftermarket units (power or output) for decades, as far as I know.

 

GeneZ, the output tubes were KT88s and the 12BY7s could drive them to full output.  Transformers would probably be the main constraint, unless there are current production units with which I'm unfamiliar.  Creating new ones would probably result in cost well beyond reason for most of us.

 

There may well be switching amplifiers in military, research, or commercial use today that could be adapted for audio - but I have no experience in that area and simply don't know.

[sandyk]

1 hour ago, GeneZ said:

 That may be something to keep an eye out for.   I wonder what the problems may be in implementing it and bringing it to the market, other than the notion that tubes are not as readily available as they once were,  and need to be replaced.  How could such speed be maintained and know when its time to replace a tube? (typical question that will be asked)

 

Let's get real here ! The DIY version could be called " The Lethal Amp" and commercial attempts would also need huge amounts of shielding as do microwave ovens etc. Lots of luck getting the FCC to pass such a design.

[bluesman]

2 minutes ago, sandyk said:

 

Let's get real here ! The DIY version could be called " The Lethal Amp" and commercial attempts would also need huge amounts of shielding as do microwave ovens etc. Lots of luck getting the FCC to pass such a design.

 

It could be done by a very dedicated, very smart, very clever, very wealthy crazy person.  But to be honest, I can't imagine that anyone would pay what it would cost for a behemoth that heats your house and sounds no better than more practical devices that are already available.

 

On the other hand, the aftermarket power cables it would spawn would make a medium sized python look emaciated  

[GeneZ]

There goes another idea ...

[GeneZ]

2 hours ago, bluesman said:

 

And the transformers in the HK CItation 2 were more than just special - the audio bandwidth of the output Xformers was 270+kHz. They've been pretty reliable in remaining C2s - most still work, with a little loving care.  There are some reports of open windings in power transformers, and there is at least one "fix" if you have the guts to open it and the luck to find the break at or near the surface. But there haven't been any new, NOS, or aftermarket units (power or output) for decades, as far as I know.

 

GeneZ, the output tubes were KT88s and the 12BY7s could drive them to full output.  Transformers would probably be the main constraint, unless there are current production units with which I'm unfamiliar.  Creating new ones would probably result in cost well beyond reason for most of us.

 

There may well be switching amplifiers in military, research, or commercial use today that could be adapted for audio - but I have no experience in that area and simply don't know.

   Someone can do away with the transformers by reviving the Futterman design. 

 

It would probably would be most appreciated by audiophiles living in one of the colder hemispheres.