Atma-Sphere Class D… Amazing

@tweak1 

   I would agree with you here. But the difference is real world mods, actual experience rather than keyboard experience/trolling. You can not say you can improve a product…. Unless you actually have done it. Real world experience with the product vs fantasy…

The thousands of audiophiles all over the world that listen to wires, fuses, jacks, etc......are LIVING PROOF that these things are real. What proof (listening tests) do you have that what they all say is wrong? Please share.

Ok. In our zero feedback tube amps we make them with custom wire, custom resistors and the like because we hear a difference (and not surprisingly, the difference is also measurable if you know what to measure). In any amplifier with really high feedback and the Gain Bandwidth product to support that feedback at all audio frequencies its a different matter! This is because the feedback of the amplifier allows it to reject a lot of the influences of the materials themselves. So in our tube amps you can hear an exotic fuse due to the voltage drop; in our class D amps you can’t, even though they are more revealing.

BTW, Nord, Apollon, VTV, etc. sell amps that have discrete input buffer option....so you can roll op amps......all op amp options sound different from each other.....this buffer is on the input of a class D Purifi module......it uses very little gain.....just like Ralph......you can also put adapter boards in these discrete op amp input boards with regular op amps on them.....yes, they sound different again....and not as good as the discrete ones.....go read their sites..

We’re very aware of how different the experience of various class D amplifiers actually is! One difficulty any class D amp has is how to drive the input comparitor which has a low input impedance and must not have any offsets of any kind at its input (and is otherwise operated well within its common mode rejection range).

So the input buffer design has an enormous effect on the performance of the amplifier. This really suggests to me that there are a lot of buffer designs that really aren’t up to snuff- and are using opamps in a way that causes the opamps to have a ’sound’. If they were designed correctly, you wouldn’t be seeing all this noise on the ’net on the ’sound’ of these amps. In short I am saying that it appears that some of the designers that made these buffers don’t know what they are doing and thus get highly variable results. If they used the opamps correctly they would get two things: less effect from the opamps themselves and a more neutral (and thus more musical) amplifier.

Getting back to Ralph’s amps, can they be stacked since they run very cool?

@lula As long as they are not being pushed hard, yes. We run them stacked here in the shop all the time.

Unfortunately they are a bit too expensive for me, will there be a cheaper stereo version ?

Great posts @atmasphere

You answered all of these questions with precision and grace. In addition, we all learned a great deal. As an avid DIYer and modifier I know many pieces of gear can benefit sonically from parts upgrades and such. However, Ralph has articulately stated why some of these mods will not yield positive results in his design. I both believe him and trust his knowledge.

Unfortunately they are a bit too expensive for me, will there be a cheaper stereo version ?

I sure hope so! I want maybe 50W/Channel stereo integrated.