Ron’s New System

[jadis]

First of all, the workmanship quality of Jadis is excellent. The construction in 3D with copper rails can't even be built in a few hours. The polished steel case is amazing.
With cathode bias, the idle current is created with a cathode resistor(red) which is bridged with an electrolytic capacitor (alternating voltage).
The gridleak resistor(blue) ensures that no grid current flows on the grid of the KT 88. This is the protection against excessive current consumption (thermal runaway of the tube. This is the rough principle of how it works.View attachment 116776
I'll explain to you using the yes 80 circuit diagram what the catch is.
1. Jadis saves one resistor + electrolytic capacitor per pair of Kt88 tubes.
This means that if they are not matched, there is an asymmetry with a pushpull amp. A slight hum is possible or wear on the tube is not the same in the long term.If you had used this combination per tube, this problem would not arise. my opinion.
2.The grid leak resistor has been chosen too large. If you look at the data sheet of a Kt 88, it says the maximum permitted values for the respective bias method. And now the vicious circle begins that leads to damage to the amplifier and tubes.View attachment 116777The only reason I can think of is that if you reduce this resistance to, for example, 150kOhm to be on the safe side, this means that the ECC 83 driver tube is being put under too much strain and the amplifier no longer sounds good.
Unfortunately, too high a grid leakage resistance leads to uncontrollable failures. As I said, it doesn't have to happen, but it can.
I hope I explained this somewhat understandably

Thanks for the thorough tech explanation. Honestly, I'm not well versed on technical things.

So, does it mean that if a Jadis 200 has 5 pairs of KT88 per channel, and 2 pairs died, one can just plug in 2 matched pairs even though the 2 pairs were sourced from 2 different tube stores with different testing parameters (same brand but different sellers for each pair)? The auto bias resistors will take care of each new pair's bias?

 

[Ron Resnick]

Could somebody please explain flow-chart style how the Jadis autobias system works?

-- What detection mechanism is monitoring the bias and detecting a different bias requirement for a new tube?

-- What intelligent mechanism is calculating what the correct bias should be?

-- What response system is actually adjusting the bias?

 

[DasguteOhr]

Thanks for the thorough tech explanation. Honestly, I'm not well versed on technical things.

So, does it mean that if a Jadis 200 has 5 pairs of KT88 per channel, and 2 pairs died, one can just plug in 2 matched pairs even though the 2 pairs were sourced from 2 different tube stores with different testing parameters (same brand but different sellers for each pair)? The auto bias resistors will take care of each new pair's bias?

correctly. It's better to focus on the input stage, as there is more sound potential there than with power tubes. The power tubes should only amplify the input signal as linearly and unaffected as possible. Of course there will be differences, but this is mainly due to the manufacturing differences and slightly different values of the tube if you simply exchange it

 

[DasguteOhr]

Could somebody please explain flow-chart style how the Jadis autobias system works?

-- What detection mechanism is monitoring the bias and detecting a different bias requirement for a new tube?

-- What intelligent mechanism is calculating what the correct bias should be?

-- What response system is actually adjusting the bias?

Look at his YouTube chanel there are very good videos where he explains it clearly and well. It's better than writing 3 pages.
Exsample biasing

 

[bonzo75]

Could somebody please explain flow-chart style how the autobias system works?

audiophile logs on to classifieds, sees bargain, buys. Spends next few months defending what he has, then sells it off. Buys new bargain, automatically starts defending it. That is auto bias

 

[DasguteOhr]

audiophile logs on to classifieds, sees bargain, buys. Spends next few months defending what he has, then sells it off. Buys new bargain, automatically starts defending it.

Audiophile circle of life.You can only break this cycle if you start reading books and then build your own amplifiers. You won't believe how good it feels when your amplifier starts making music. Once you've tasted blood, the projects get bigger

 

[Johan K]

Sangre por sangre - blood for blood !

 

[Johan K]

Ron,

From tubes to something different…
How’s your turntable, and tonearms comming along?

 

[DasguteOhr]

Sangre por sangre - blood for blood !

not so martial, bad choice of words on my part. Of course, you can also be happy if you have found the right device. For me it was always the case that something was missing or I didn't like something, hence this path. The advantage is that you don't become stupider if you know how it works, even if not every project is a success.

 

[jadis]

I had heard and helped set up a friend's VAC 450S iQ stereo amp and was immediately fascinated by the auto bias system it employed. I believe it is one of the most sophisticated auto biasing system around. Here is the link to a more technical explanation about fixed bias and cathode bias and VAC's own intelligent bias. From the looks of it, Jadis Class A amps use either of the first 2 and I was told by tech men, all you need to do after a tube failure is to change the failed tube and its partner with a matched pair tube. From my understanding and I might be wrong, VAC's system does not need a matched pair if 1 tubes failed (as indicated by its blue LED light), you just need to plug in 1 brand new tube.

http://www.vac-amps.com/press/factsheets/iQsystem.pdf

PS: I now recall that there was never a red light showing up among the 20 LEDs. None of the 20 small fuses ever snapped, and none of the 20 GE6550s ever failed in my 3-4 years of use. The caps of the power supply were the ones always breaking.

 

[Salectric]

Audiophile circle of life.You can only break this cycle if you start reading books and then build your own amplifiers. You won't believe how good it feels when your amplifier starts making music. Once you've tasted blood, the projects get bigger

Certainly true in my experience. I realize this is not a DIY forum but there really is nothing quite comparable to building your own amplifier and turning it on for the first time.

 

[Ron Resnick]

In tube audio amplifiers, how does cathode auto-bias work?

Cathode auto-bias, also known as self-bias, is a circuit design in tube audio amplifiers that allows the amplifier to automatically adjust bias voltage at the tube's cathode to maintain proper operating conditions. This is achieved by using a resistor-capacitor (RC) network in the cathode circuit. The resistor provides a fixed bias, while the capacitor allows for AC signals to bypass the bias, maintaining stable bias voltage for the tube during signal variations.


But how does this result in tubes of different electrical characteristics being able to be used in the same circuit?

Cathode auto-biasing in tube audio amplifiers accommodates tubes with varying electrical characteristics by allowing each tube to establish its own operating point based on its specific characteristics. The resistor in the cathode circuit sets a baseline bias, but the AC signal's variations are capacitively coupled, effectively decoupling the bias from the AC signal.

Since different tubes have diverse characteristics, such as transconductance and amplification factor, they will draw varying currents for a given bias voltage. The cathode resistor compensates for these differences, allowing each tube to find its optimal operating point by adjusting its cathode voltage accordingly.

In essence, cathode auto-biasing enables tubes with different electrical characteristics to coexist in the same circuit by allowing each tube to self-adjust its operating parameters, ensuring proper functionality and sound quality.

Now I understand!

 

[Folsom]

I appreciate you thinking about my system!

What is your concern about the power cables?

Questions about capacitance were raised by others on the thread here, not by me. I have no concern that interconnect capacitance is causing any sonic problems. If anything I have no objection to a little HF roll-off. I have no actionable concern regarding capacitance.

Power cables can utterly change the entire sound of a stereo. I've heard some expensive cables do very strange things to the music. That's why I am all for establishing a baseline. You can go years before you do and then one day when you do, realize just how much you've been fighting something you didn't look at. I simply don't consider them innocent where choosing non-standardish ones is subtle and not that important.

You know it's not rolling off the frequencies really, it's rolling off the volume. Capacitance changes dynamic characteristics as the first most notable thing. If you want to know the max dynamics you go with pretty low C, to see if you even want that. But at that point some things like odd power cables may become less attractive in quality because there's nothing to soften the blow of what they do. I'm sure many power cables are enjoyable but because they are so drastic on the sound you have to really check if it's a band or a boon.

 

[Ron Resnick]

It turns out that Angela Cardas herself prefers (circa 2018) Clear Reflection in her own system over Clear Beyond (because the Clear Reflection is a bit warmer).

The capacitance of Clear Reflection is 21.8 pf/ft., well below that of the Belden 1192A.

Clear Reflection is less than 1/4 of the price of Clear Beyond. I think I'm going to try it.

 

[Folsom]

It turns out that Angela Cardas herself prefers (circa 2018) Clear Reflection in her own system over Clear Beyond (because the Clear Reflection is a bit warmer).

The capacitance of Clear Reflection is 21.8 pf/ft., well below that of the Belden 1192A.

Clear Reflection is less than 1/4 of the price of Clear Beyond. I think I'm going to try it.

That is interesting. I guess I can support trying it based on capacitance levels. But only if there is no rhodium in the connectors. Even then I am 100% about baseline.

I am interested in your stereo, and that it is what you really want. We haven't been following your journey for the better part of a decade to stop caring that it turns out well. I guess one could say beware the noob linearity, or maybe better put "more of the same".

And FYI I do remember you not wanting to have to do a observational study on every component imaginable within the stereo, to the point where you aren't going to roll everything over and over.

I guess we should be asking you, what do you want to gain from Cardas cables?

 

[Ron Resnick]

That is interesting. I guess I can support trying it based on capacitance levels.

Okay

But only if there is no rhodium in the connectors.

Cardas uses rhodium somewhere in the connector.

I am interested in your stereo, and that it is what you really want. We haven't been following your journey for the better part of a decade to stop caring that it turns out well.

Thank you!

I do remember you not wanting to have to do a observational study on every component imaginable within the stereo, to the point where you aren't going to roll everything over and over.

Yes, I don't have the patience to do this the right way. The right way would be getting six or ten or a dozen 46 foot interconnects, and doing my best to impersonate Marty.

I am not convinced that swapping out different 1m interconnects between the phono stage and the line stage would answer the question as to what is the best interconnect for my ears between the line stage and the amplifiers.

I guess we should be asking you, what do you want to gain from Cardas cables?

I am trying to gain a bit of warmth/richness versus the Belden 1192A.

Virtually no one ever suggests that any Cardas cable is bright or edgy or lean or thin-sounding. Especially if Angela thinks Clear Reflection has a touch of desirable warmth I think it is a slightly educated bet to give this relatively low capacitance cable a try.

 

[Salectric]

Trying different 1m interconnects between your phono and linestage would be very useful. It’s an easy way to demonstrate the differences between cables relative to each other. You can make relative judgments that will assist in deciding on longer cables. The Belden 1192a cables you are using now are good enough for you to make fairly reliable predictions about how longer cables will sound. For example you might find the 1m Cardas cables are too colored for your tastes. It would be much better to find that out before ordering a long set of Cardas cables. And even a little firsthand experience will be more helpful than reading opinions of other people.

If you want the 1192a to be warmer and richer, that’s easy. Just replace the generic RCA plugs that came with your Belden cables with ETI Copper Links. The Copper Links sound very good but lean towards the warm/rich side. I am listening right now to a 5m pair of 1192a cables with Copper Links and they sound very good indeed. The cables only have 40 hours so they are still breaking in, but I am very familiar with Copper Links from other cables I have.

 

[microstrip]

In tube audio amplifiers, how does cathode auto-bias work?

Cathode auto-bias, also known as self-bias, is a circuit design in tube audio amplifiers that allows the amplifier to automatically adjust bias voltage at the tube's cathode to maintain proper operating conditions. This is achieved by using a resistor-capacitor (RC) network in the cathode circuit. The resistor provides a fixed bias, while the capacitor allows for AC signals to bypass the bias, maintaining stable bias voltage for the tube during signal variations.


But how does this result in tubes of different electrical characteristics being able to be used in the same circuit?

Cathode auto-biasing in tube audio amplifiers accommodates tubes with varying electrical characteristics by allowing each tube to establish its own operating point based on its specific characteristics. The resistor in the cathode circuit sets a baseline bias, but the AC signal's variations are capacitively coupled, effectively decoupling the bias from the AC signal.

Since different tubes have diverse characteristics, such as transconductance and amplification factor, they will draw varying currents for a given bias voltage. The cathode resistor compensates for these differences, allowing each tube to find its optimal operating point by adjusting its cathode voltage accordingly.

In essence, cathode auto-biasing enables tubes with different electrical characteristics to coexist in the same circuit by allowing each tube to self-adjust its operating parameters, ensuring proper functionality and sound quality.

Now I understand!

Then you have to add that since different tubes have different cathode to grid voltage for the same current, the current flowing through tubes in cathode bias depends on tube characteristics and you have to use the proper matched tubes for proper operation of the amplifier.

Cathode bias was a magic tool for radio receiver or amplifiers where only an approximate current was needed. In high performance high end amplifiers the cathode bias performance is strongly linked to tube selection - it is why Jadis tubes are so critical.

I do not know about the JA100, but some JA80's shared the cathode resistors between tubes, making matching even more critical. BTW, proper matching means matching the tubes at the operating current of the tubes in the amplifier, not a the low current used by most tube testers.


.

 

[Hi-FiGuy]

Tom is officially retired.

That is too bad but I get it completely.
At one of the LAOCAS meetings at Berdans he was giving a speech about equipment testing and he asked us if we wanted him to tell us how to hear(forget what kind) a particular form of distortion and he said "once I show you you will never not hear it for the rest of your life." and in perfect unison, everyoune there said loud and clear NO! He shut up about it right there and moved on and henever said another word about it

Solid Guy

 

[Audiohertz2]

At least everyone there was being Honest