I don't know what people around here think of Berning's ZOTL, so I'd like
some comments on the idea (at least reviews of the sound of the amplifiers
are quite positive). I don't like audio transformers and so for tube amps
I've mainly messed with headphones, electrostatics and plasma as they are
easy to drive directly. In the ZOTL, there is still a transformer, but it
is running at far above audio frequencies, and the curve traces on the
website look good and don't appear affected by going through the
transformer on the carrier wave, but what's the marketing BS leaving out?
I'm thinking of trying to DIY an amp based on this idea, as I'm pretty sure
that patent law doesn't apply to personal experimentation. I've already
got large potted ferrite cores, and my LTSPice simulation of the circuit
from the patent works, though I don't have a very good transformer model.
Still, I'm sure the devil's in the details, and there's a lot of them here.
How to choose rectifiers that would have appropriate switching
characteristics, for example.

Helpful comments are appreciated. Even from Patrick Turner :-P

Prune wrote:

I don't know what people around here think of Berning's ZOTL, so I'd like
some comments on the idea (at least reviews of the sound of the amplifiers
are quite positive). I don't like audio transformers and so for tube amps
I've mainly messed with headphones, electrostatics and plasma as they are
easy to drive directly. In the ZOTL, there is still a transformer, but it
is running at far above audio frequencies, and the curve traces on the
website look good and don't appear affected by going through the
transformer on the carrier wave, but what's the marketing BS leaving out?
I'm thinking of trying to DIY an amp based on this idea, as I'm pretty sure
that patent law doesn't apply to personal experimentation. I've already
got large potted ferrite cores, and my LTSPice simulation of the circuit
from the patent works, though I don't have a very good transformer model.
Still, I'm sure the devil's in the details, and there's a lot of them here.
How to choose rectifiers that would have appropriate switching
characteristics, for example.

Helpful comments are appreciated. Even from Patrick Turner :-P

I am not entirely familiar with the workings of the amp by Berning.

I make OPTs with BW from 14Hz to 300kHz at full power.
Its easy when you know how, and use the extra 2 hours of labour to get there.
So at lower normal average levels at say -12dB voltage levels the BW
will be 3Hz to 300 kHz, since we keep away from saturation regions.

The iron caused distortion is very much less than that of the output tubes
at any F using the GOSS core material I now use.

OPTs allow excellent load matching for the tubes.

In a digital amp the device is either on, or off, and the class of operation
need only be class B.

Here is what i said to someone about some latest solid state digital amps....


" Today a dude fronted my work shop with a pair of SS amps that looked quite
strange.

They were SS mono amps about like a 150mm cube, with a 300VA toroidal power
tranny, two TO220
devices bolted to a small heatsink, but rated for 100watts.
There was a 50mm square circuit board with about 5 second generation chips and
opamps,
and a bunch of almost invisible other surface mount devices.
There was an inductor in the centre, small, about 15mm cube, a potted coil.

Welcome to the future. This was a digital amp, probably PWM,
and its 95% efficient, hence no heatsink, it never gets hot.

One has a hiss in it, and the makers sent the owner a free new board.
The whole 100watt amp module is the size of a match box, and has a 5 wire cable
and plug
and is held by two easily accessable screws, so the amp module
can be changed in 20 seconds, really, no BS.

I can visualize that this sort of amp will soon be addopted by
99% of the mainstream makers within 10 years, and amp makers like Krell
won't only be trying to justify their class A monstrosities against the class B
opposition,
but also against the likes of the new digital amps which by then will have
matured a
little more than they have, and may not develop faults like the sample that
arrived at my door..

People will say these digital amps sound like crap.
The owner who arrived for help with these two amps reckoned the sound was
great,
until he got this hiss problem.
Not all new things run fine; the first bjt amps were horror stories too.
Trouble is, after forty years they have not become better than tubes.

Anyway, not all will agree that digital amps are fine, so tubes will stay,
appealing to a minority, as they do now, despite the presence of existing
analog SS amps.
But if the new digital amps are as good as the class A SS amp and all the rest
of the SS class AB analog amps, then all the existing amp makers are wasting
time bringing more
class A and AB analog designs onto the market.

They simply won't compete.

These amps I see in front of me have tiny boards which could be made for
peanuts, because the technique has become routine for mobile phones and
1,001 different mass produced electronic items, and as we all know, demand has
no
limits, billions of ppl remain to want electronics....
They have no heatsink other than a 4mm thick back plate to make the amp
look pretty, rather than cool it. They run cool, even when making lots of
power.
No thermal breakdowns, the bjts are either "on", or "off", simple.

Its now so easy to have 6 amp channels each of 100 watts, and the material and
labour
and item weight and raw material content will be all a lot less than any 600
watt analog amp
ever made before.

But of course we now have a world full of talent not worth having 6 channels to
convey it,
but then when rock and roll shocked my parents they whinged about having to
have stereo
at great extra cost and what for? those screaming gits who cannot sing.

But my generation lapped up the stereo and lerved the screams of pop stars
who sounded worse than a tom cat with a cracker up its arse."



So we could have tubes doing similar things to the switching that goes on in
transistor switching amps, or pulse code whatchamuckallits or whatever.

Once one uses a concept of switching, pulse width modulation, with demodulation

via some reactive circuit, and shirtloads of NFB, one has not the slightest
need to have linear devices; we simply need fast switching cabability,
and the control of the width of the pulse with NFB does the rest.
So I doubt any amp operating as a switcheroo type
would sound any different with tubes, bjts, or mosfets.

I am pig ignorant of what Berning is trying to achieve, I recall going to a
site
but I don't recall seeing a diagram with operating waveforms drawn alongside a
schematic that would be easy for a average idiot like me to understand.


Class A triodes have simplicity, always have, always will.

Patrick Turner.

Patrick Turner wrote:
I am not entirely familiar with the workings of the amp by Berning.

One look at the figures in patent 5,612,646 (use free.patentfetcher.com or
www.pat2pdf.com) will give you the idea. The tube output rides the
switcher carrier wave, with the switcher circuit giving no power gain and
serving to provide the load matching. Transfer characteristics are pictured
he http://www.davidberning.com/Transfer Char.htm

Also, it's a pretty cool idea, and unusual, which is one of the things that
attracts me to it.

The iron caused distortion is very much less than that of the output
tubes at any F using the GOSS core material I now use.

I was under the understanding that output tube distortion can be dealt with
by Hawksford error correction, from discussion I read at diyaudio.com's
tube forum.

In a digital amp the device is either on, or off, and the class of
operation need only be class B.

Well, the tube here can operate in class A. I don't care about efficiency.
(Heck, I'm building a pair of Aleph-X monoblocks for the 500 Hz drivers
to couple with my 500 Hz plasma project, and I'm estimating close to 2 kW
drawn from the mains. Not to mention the 3 kW supply driving my 120 kV X-
ray tube -- diy cone beam tomography is fun )

Prune wrote:

Patrick Turner wrote:
I am not entirely familiar with the workings of the amp by Berning.

One look at the figures in patent 5,612,646 (use free.patentfetcher.com or
www.pat2pdf.com) will give you the idea. The tube output rides the
switcher carrier wave, with the switcher circuit giving no power gain and
serving to provide the load matching. Transfer characteristics are pictured
he http://www.davidberning.com/Transfer Char.htm

Also, it's a pretty cool idea, and unusual, which is one of the things that
attracts me to it.

The iron caused distortion is very much less than that of the output
tubes at any F using the GOSS core material I now use.

I was under the understanding that output tube distortion can be dealt with
by Hawksford error correction, from discussion I read at diyaudio.com's
tube forum.

Maybe.



In a digital amp the device is either on, or off, and the class of
operation need only be class B.

Well, the tube here can operate in class A. I don't care about efficiency.
(Heck, I'm building a pair of Aleph-X monoblocks for the 500 Hz drivers
to couple with my 500 Hz plasma project, and I'm estimating close to 2 kW
drawn from the mains. Not to mention the 3 kW supply driving my 120 kV X-
ray tube -- diy cone beam tomography is fun )

Be careful with Xrays, you might see through yourself,
and realize you have other dimensions in time and space.

Patrick Turner.