Who will survive? One last table til I die.

Good grief, Raul, get over yourself.

Dear Gregadd and friends: ****" Raul this is from an earlier post by you. The audioholics does not agree with your conclusion that a tube amp is an ucorrectable equalizer. "*****

They don't disagree too, right?. But this is not the point, the point is that till today does not exist any tube amplifier with very low output impedance. That's why a tube amplifier change the frecuency response with the changes that has the speaker. Now, in and SS amplifier that changes can be of a very low order: 0.1 db to 0.3 db, but in a tube amplifier that changes are really high ones deviations from the original: 0.5 to 10db or more. This is a heavy degradation. Take the TWL amplifier that has an output impedance of 1.8 Ohms, this one will had a deviation between 1.0 to 2.5 db: unacceptable by any standard.

TWL post this: ****" To me, the key here is not whether there may be some slight affects to the amplifer based on speaker reactances, but whether these small effects could even be actually audible, given wider range tolerances in many other parts of the sytem context. "****

Dear TWL, first there are not " slight effects " ( ****" , As amplifier output impedance rises, these differences in frequency response are exaggerated. The changing speaker impedance actually pushes the output voltage of the amplifier around thereby changing the acoustic output of the speaker. The amplifier cannot control its own output. "**** This comes from the Gregadd link. ), in the case of tube electronics it is a heavy effects ( degradation and always audible by anyone, but a deaf. ) ), second: what are you telling us? that because there are other wider range effects in other parts of the audio system, these ones does not matters?. Example: assume that the discrete frecuency response at 100 Hz of a speaker has a deviation of -10 db and that the effect of the tube amplifier is -3 db at that discrete frecuency: TWL, till today 10+3 sum: 13 ( I know that the sum of db it will be a logarithymic sum ) and you try to telling that it does not matters?, come on TWL.

Now, the tube amplifier degradation to the signal is worst than what Stereophile shows in the diagrams, why?, because Norton/Atkinson use a constant resistance at the amplifier outputs, normally a 8, 4 and 2 Ohms resistors. This is very gentle for the tube amplifier and far from reallity, because the impedance of the speaker is not constant it has heavy variations with the frecuency response in all the frecuency spectrum, and you can check this too through the Stereophile tests on speakers,: can you imagine other worst degradation on the signal reproduction in a high end audio system and that that degradation can hear it?

This is one of the reasons why I always speak of " equalizers " in reference to tube electronics. The real name has to be: UNCONTROLLABLE EQUALIZERS.

It is already clear that the tube electronics goes against the music reproduction, and till now anyone can do nothing for to change it. This is the point: AGAINST THE MUSIC REPRODUCTION.

All these statements are for the people that really cares about. Ask you what are you hearing from a tube electronics in front of live music.

In this analog forum all of us are trying to obtain the best from our analog system: phono preamp, phono cartridge, tonearm, turntable, phono cables, etc.... Here we are talking to do the very best for our analog system: VTA, VTF, Azymuth, cartridge load impedance, resonnce frecuency on the cartridge/tonearm combo, metal platter or acrylic one, MC or MM cartridges, pivot or linear traking tonearms, air bearings, mass, etc..... We do all this job ( time, money, know-how,..) trying to obtain the best analog music reproduction, and for what if in the next audio system link: UNCONTROLLABLE EQUALIZERS ( tube electronics ), all our efforts goes dead-down.

That's why I always speak to be sure that exist the LESS degraded effects at any link in the whole audio system, and why any one that has these UE does not knows the real performance of his audio system.

Regards and always enjoy the music.
Raul.

Dear TWL: This is what you post against me in this thread: ****" I actually think that you know very little about audio. " **** and

****" I'd suggest quite a bit more study before engaging any serious audiophiles here again. " ****.

I think that all of us ( including you and Chris ) now are more knowledge about. Don't you think?.

Rushton, as you can see the OTL is no solution: it's worst.

Gregadd, tks for your info .

Regards and enjoy the music.
Raul.

I think I'm going to hit myself in the head with a hammer...

"OTL
Let’s look at the Transcendent T8 as an example. It uses 8, EL509 tubes in push-pull. Each 509 has a plate impedance of about 150 ohms. 150 ÷8 = 18.75 ohms. This is unacceptable. Negative feedback is employed to achieve proper performance. The amplifier uses 33 dB of negative feedback which reduces the output impedance to 0.4 ohm thereby achieving outstanding woofer control and the ability to drive 4 ohm speakers. This specification was verified by Stereophile when they reviewed the amplifier."

Direct quote from the link in my previous post.

Now here is a quote from Raul:

"... The output impedance in the tubes amplifiers, usually, goes from 0.5 to 3 OHms ( high one ) and the output impedance in the SS goes from 0.02 to 0.5 OHms ( very low one..."

Consequently, given the range that Raul has given, there is a tube amp with output impedance in the range of SS. If the Transcendent amp is an uncontrollable equalizer so is a ss amp.
Others can see that Raul conitnues to move the goal post.

Pardon me while I continue to bang my head...

As I stated above before you make major changes in your system to obtain full spectrum frequency balance you should study what a real frequency curve of a real speaker operating into a real room (not an anechoic chamber)looks like. Moreover you need to examine what empahasis the human ear puts on the frequency spectrum.

Raul, I would refer you to the David Berning website, in the White Papers section, where amplifier transfer characteristics are discussed.

You may know that the "load line" of a given amplification device in an amplifier defines how it responds to the loads presented to it by the speaker(load) and how well it will control it directly and without feedback.

In my Berning amplifier, the load line is about 1.8 ohms, and it operates with no feedback, and is globally DC stabilized(something you seemed to think could only be in SS amps, and not be achieved with tube circuits, but is a feature of the David Berning ZOTL circuit). However, by using the much larger "effective turns ratio" that is provided by the unique ZOTL impedance conversion circuit, much more effective control of the speaker load by the triode is possible, than would ever be possible using any output transformer or traditional OTL ciruits. In fact, with the load line that is in my amplifier, according to the David Berning "White Paper",

"In an audio application, the tube behaves as if it is driving a 4k ohm speaker (the impedance conversion ratio goes as the square of the turns ratio), and the speaker acts and sounds as if it is being driven by a 0.6 ohm triode."

And this, with the use of ZERO FEEDBACK. The natural load line of the triode is sufficient to produce this, when using the ZOTL impedance converter design. So that all the linear transfer characteristics of the triode are preserved, and full control of the load is realized, while exceeding the capability(and eliminating any of the drawbacks) of any output transformers.

So, as you can see, the use of this design allows both a low output impedance AND zero feedback, and at the same time eliminates all the saturation problems and parasitic capacitances of typical output transformers in audio applications, and still allows the use of a single triode(no parallel tubes like traditional OTL) to control the speaker accurately and in conditions of shifting speaker impedances(within reason), based on its inherent transfer characteristics(load line)in conjunction with the Berning ZOTL impedance converter.

While David does give credence to your concerns about shifting impedances causing frequency response problems in certain amplifiers, it is shown that this amplifier circuit is not adversely affected by the things that you mention, and the load lines in the ZOTL circuit are very close to what would be expected from some MOSFET transistor amplifiers(without feedback). However, the sonic attributes of the triodes are preserved, and gives what might be called "the best of both worlds", as the control and speed are very much like solid state, and the transparency, tone, and harmonic qualities are all tube.

So, here we have a tube amp with a single output triode(per channel), no audio output transformers, no feedback, an effective output impedance of about 0.6 ohms, DC coupled and global DC stabilization, bandwith from 2Hz - 500kHz, high-speed switching power supply, RF-frequency tube heating, noise less than -100db, choke loading, DC powered, auto-biasing, brownout protection, and can even be turned on without any speaker attached without damage(just like a SS amp can), and weighs 5 pounds.

And best of all, it sounds like real music when you use it with a good speaker. It doesn't sound like most tube amps, and it doesn't sound like most SS amps. It sounds like the best of both.

Now, by anybody's numbers, a 1:13 ratio(damping factor 13) of output impedance to speaker impedance is going to be well within 1db(and probably within 0.5db) in frequency response variation over the audio range as long as a nominal 8 ohm speaker is used. Now, if you want to drive Apogee Scintilla's <1 ohm load with it, I'll agree that I cannot do it with this amp effectively. For the speakers that are intended for this amp, it will control them admirably and exhibit a quite flat response, and be musical.

Whew! I'm tired, and had about enough of this.

Regards,
Twl