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David Berning "Holy Grail" 45 SE ZOTL now exists

Yes folks, it's here. For those of you who have been following my system, there has been some anticipation of the delivery of this new amp. And it has arrived.

For those who aren't aware of this amp. It is a fully custom one-of-a-kind handmade amp by David Berning that was constructed to my specifications by special order. It carries a "Prototype" designation, as a non-production unit.

I have named it the "Holy Grail" because it has characteristics that have never before been available in any amp at any price. It is a Single-Ended Triode design using Type 45 output triodes, and 6SN7 drivers. The amp is a variation of OTL(output transformerless) called ZOTL that is proprietary to David Berning, and is the only circuit in the world that can commercially achieve true SET configuration without an output transformer. This is special enough, but this unit also features choke-loaded plates for much greater linearity than resistive loaded plates, and has a custom choke hand wound by David Berning. To top it all off, it is powered by battery only, from a 12vdc deep cycle marine battery, that provides the cleanest power possible, with no AC grunge, and no step-down transformer or rectifiers in the power supply, for a smooth ripple-free power feed, and no hum fields generated by the power transformer. This is the only amp ever made with this particular set of features, and makes it probably the most advanced form of tube amplifier ever made.

Prior to the invention of ZOTL it was impractical, or impossible, to make a true SET amplifier that was OTL. Now it is possible, and is being done, not only in my amp, but in the Berning Siegfried as well. Achieving this SET "magic" sound without the intrusion of an output transformer between the triode and the speaker is truly revolutionary, and revelatory in its sound quality.

Choke loading is being used by some of the best tube amp makers to improve the sound of their amps, and is a very nice improvement over resistive loading, but comes at a high cost. I selected this because of the sonics, and not the cost factor, because I wanted the best in a cost-no-object design.

Battery power is the cutting edge of power conditioning. It totally eclipses what power conditioning can do, and goes into territory that exceeds any AC powered amp.

The entire audio circuit is hand wired point-to-point. Top quality parts,jacks, and posts are used.

I selected the Emission Labs mesh-plate 45 triodes for their sound quality, and ruggedness over all others for this application, and use NOS Sylvania 6SN7 GT tubes for the drivers, for their "sweet" tone quality, and delicacy of detail.

The reason I selected the name "Holy Grail" for this amp, was because it has achieved something that has been sought after for years, but has never been attainable until now. The magic of SET, in an OTL configuration with the ultimate in power supply, and a choke loading, and type 45 tubes, which are legendary for their awesome tone.

I have done some preliminary listening tests with this amp, and the sound definitely lives up to the name. It is indescribe-able really. My basic impression is that it sounds like a high-end solid state amp, with triodes. By that, I mean that it has full frequency range, with no roll-offs on either end, and has punch and slam like a solid state amp, while having the SET magic sound all the way from top to bottom. I know this sounds unbelievable, but that is what it is. This amp has test charts accompanying it, and it reproduces a 20kHz square wave with a perfectly vertical rise time. Try that with an output transformer. 30Hz square waves look just as good. The amp is not DC coupled, so the coupling cap introduces just a touch of trail-off on the square wave peaks. Very minimal. On the load-line scope traces, there is no looping distortion. The bandwidth extends into the RF zone, which has a "hole" aroung the 250kHz ZOTL carrier, and then picks up again and extends to over 500kHz. Is that wide enough bandwidth for you?

I could go on and on about this, but this is simply the most awesome amplifier ever made, in my humble opinion. And the sound is just exquisitely beautiful. If you could imagine a SET with SS highs, lows, dynamics, and slam, and no grunge or grain at all, this is what we have here. I am almost at a loss for words.

I just wanted to share this with whomever wants to hear about this, because it is truly a landmark that has never ever been done before. The Holy Grail.

I will try to answer any questions or happily entertain any comments anyone may have about the amp, or my criteria for its design.
twl
twl OP
3,251 posts
 
Tubegroover, I would like to feel as though I am helping to carry on Dr. Gizmo's legacy with this design, and I have even mentioned that to David Berning. As you know he and Gizmo did some things together, and Harvey even coined the name "ZOTL".

After reading most of the articles on the Triode Guild, I felt that a battery powered, single ended, choke loaded ZOTL, with 45s, would be Harvey's idea of the "creamiest of the Triode Cream" and a virtual cornucopia of "Thermionic Coolosity". To say nothing of the studly appearance of those 7" tall 45s standing above deck. And again, it is David Berning (and me), who reached up to new heights of Alien Triode technology to make this bold step into the far reaches of cosmic triode universe.

I think the Dr. would be proud that this step has been taken, and maybe might have even been taken by him, if he were still alive. But since he's not, I took the step to advance the state of the triode art, and get all the attention from Miss Triode Guild 2002.

Dr. Gizmo lives!
twl OP
3,251 posts
 
Asa, I'll be looking next spring for preamps. Jayarr, thanks, and I know you are loving your Siegfried!
rwd
695 posts
 
TWL....so happy you have your new baby! From what I've read this should keep you in Hi-Fi heaven for quite some time. Keep us all posted as to the progress...

BTW...I am not a horn person....and you indicatred that you get gerat "slam" base from your speakers....do you use a regular driver for the bass?
twl OP
3,251 posts
 
Rwd, my speakers are not horns. They are direct-radiator single-drivers, which use a complex loading of the rear wave, called a Tapered Quarter Wave Pipe. The moniker used is generally "Voigt Pipe" named after the inventer. The rear wave of the driver is funnelled through a cabinet that uses Transmission Line, Bass Reflex, and rear horn loading, to augment just the lower bass frequencies. This is not perfect, but does a pretty good job, and does not impart the colorations like a front-horn system does. This is not to say it has no colorations, but they are less severe than the front horn types, and are more like direct-radiator speakers with some vented-box type colorations. Not bad, but nothing is perfect. I get the efficiency I need with no horns.

The "Slam" I get is from the Lowthers, believe it or not. They only go to about 40Hz, but have a rolloff below that, and the dynamics of the driver is imparted to the bass frequencies as well as the rest of the range. When you hook up an amp with the bottom end speed that the Berning has, you actually do get "slam". This was not previously the case because most times, Lowthers get used with typical SET amps, which have some challenges in reproducing fast tight bass. It is not like a pair of super-subs with dedicated Krell amps, but it has a modicum of "slam" in the sound. More than you would ever expect from a 2 watt SET amp. It sounds more like a SS amp in the bottom, like maybe a Pass Aleph 30 watt. Because it has the extension, speed and lack of bloat that normally is not present in most SET amps, and is usually characteristic of SS amps. But the excellent tube tone quality is still there, just fast and tight. Midrange and high end are also lightning fast. This system is a speed demon. Not a hint of sluggishness here.

Thanks for your sentiments, about being happy for me getting the amp. I appreciate that alot, and I am happy with it.
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