Ron’s New System
- Thread starter Ron Resnick
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Read the comment I linked to, it's at the bottom of page. Someone that was familiar with Jadis topologies talked about how they're designed. But the tube count alone tells you that there has to be some feedback. And the measurements confirm they have enough to stay stable as they distortion is pretty low at the start and gains some - similar to other things you look at.
It is a four way set up active crossover (Accuphase F25 crossover), as in my signature. Bass goes to subwoofers below 80 Hz crossover point; 80 to 300 Hz crossover goes to Analysis bass panels with Wavac MD572 amplifier; midrange crossover goes 300 to 7Khz to 15 watt Wavac MD811 amplifier to 75 inch ribbons, and foil tweeters 7khz crossover and above.
Pendragon's single passive crossover is 250 Hz and bass towers cover both bass, upper bass, and lowest midrange. Pendragon does have a tweeter which is 'additive' without crossover but set high at 18 khz or so.
So, in effect something rather modestly powered should also work without too much strain.
LOL! You said it, I didn't. Ron Room is larger, larger air spring, passive crossover with less efficiency, etc. etc.
Larger air mass would have potential for greater dynamic shading, I would presume, also require more power with the passive crossover.
However, as an experiment, a 300b SET in the Ron Room on the 75 inch ribbon might have an interesting result (note I said interesting, not necessarily ultimately desirable). I don't see anything like that making its way in there, though.
You should ask if it does use global negative feedback. Jadis usually uses local feedback between the input and drive and also global feedback, it is shown in their schematics. We can also guess it from the low output impedance measurement.
As far as I remember only the Jadis SET's are global feedback free.
An ancient Yamaha M-35 SS amp. Currently to a couple of Aurum Cantus foil tweeters (with Graz foils after market) on each side.
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As is the wont of officious armchair audiophiles spending other people’s money, and armed with an expense account on Ron’s dime, I would:
1. Find the takeoff points of the direct speaker inputs on the bass towers and ribbons and put speaker leads on them, bypassing the passive crossover and the bass tower amp.
2. Use an Accuphase F-20 (two way active crossover with phase, slope and volume adjustments) with a 250 Hz card and take the preamp outputs to this active crossover
3. Direct the low pass to the Siegfried’s then directly to the bass towers.
4. Direct the high pass direct to the ribbons with an amp not to exceed 50 watts, likely less, in direct drive, something preferably single ended.
Since I’m spending Ron’s limitless audiophile budget, maybe a nice Lamm ML3 on the ribbons. That’s a system that would attract the audio pilgrims. Maybe add a couple of ‘additive’ subterranean subwoofers crossed over @ 40 Hz or so.
Thank you, Ron, that was your money well spent.
Thank you, cjfrbw! I'll let Tinka and Lola know that we won't be eating for a year or two.
Actually, I like this set-up a lot!
what Analysis bass panels are you using? Did you have to do surgery on one of their full range speakers?
The Analysis Epsilon speakers came with external passive crossovers, so the speaker leads are direct to panels. That made it easy to insert the active crossovers.
Fantasy system is a bit of a josh, of course, but yes, VIVA 845 would probably do the trick, especially in direct drive. 845 is a more linear tube generally than some of the other transmitting tube types. The GM 70 is also a linear triode.
By "linear" in this context do you mean, in general, depending on the circuit of course, less upper bass/lower midrange "warmth" or focus than, for example, 833 or EL34?
Has to do more with determining the AC 'load line' of the amplifier, producing output dynamics that track the input dynamic more accurately with least amount of compression or distortion.
That is easier to do with tubes that are inherently linear to begin with, as the curves in the diagram shown by morricab above for the 845. It is harder to get that linearity with 'pentode' curves, which are different.
I think the elusive 'warmth' factor may have more to do with distortion profiles and relations of second and third harmonics. Also, the sense of response and 'bloom' of particular tubes. This is still a hotly debated issue.
I have only ever seen one Wavac amp ever measured, and that was the 833 model reviewed some time back in Stereophile. 833 tube has a more 'pentode like' curve as opposed to the 'triode' curves like the 845. That 833 amp, even with the massive extra power supply chassis, could barely make specs out to a couple of watts and was up to 15 percent distortion at peak power. Nonetheless, the subjective impression appeared to be highly favorable.
Shishido said his amps were all one watt amps and that everything else was overhead depending on the speaker efficiency and demand.
That gets into the bag of worms of how particular distortions can aid the auditory apparatus into hearing the signal in a way that is subjectively pleasing. I know that desirable warmth factor in the upper bass/lower midrange and I crave it, too. I think tubes do that better in general and thus the Sigfrieds on the bass towers.
My speculator speculates on the Wavac that the first watt or two have good distortion figures, but that as the power demand rises, so do the pleasing distortions to give the warmth. It winds up producing an organic effect that also enhances detail, space and dimensional perception in some ineluctable manner. Maybe the transformer grid biasing arrangement in A2 is just a better way of doing it.
Of course, there is the standard accusation that these tubes are 'tone controls'. But it begs the question, if they allow you to hear the detail, dimensionality and tone better, and enhance emotional engagement, are they better for people while being worse for robots?
Wavac does not make everything sound 'good', but it does present in a way that is diplomatic at the least.
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Stavros Danos , Aries Research.
The 813 Tube
“The Concero 65 Signature uses a parallel pair of RCA 813 tubes in the output stage. As an output tube, we believe this tube is one of the most linear tubes ever built. Triode curves quality are unmatched even by the most linear 300B tubes for example. And of course most bigger triodes like the 833 are far behind in both linearity and sonic performance.This 813 big bottle tube never ceases to impress us whenever we compare it in our labs with ANY power tube used today, and is our weapon of choice when designing SOTA SET amplifiers.”
