Looks, price tag, prestige, and a general insensitivity to distortion. Don't know about Wavac, but Jadis offers the extra benefit of regularly emitting smoke.
It would be interesting to listen the same speakers used in the tests but driven by a normal cheap amp .. like the T-amp for instance
Maybe there will be some kind of surprise
For me distorted is synonym to deformed ... not a nice sensation
It could be the name 300B. When applied to any amplifier, including at least one which does not contain the said valve, it appears to affect listeners' perceptions.
30-40 years ago a similar effect was common in IT: anything labelled IBM was regarded as good, no matter how expensive or inappropriate it was.
I'm not knocking the 300B or IBM, as both are capable of good results. However, neither guarantees good results when misapplied.
30-40 years ago a similar effect was common in IT: anything labelled IBM was regarded as good, no matter how expensive or inappropriate it was.
I'm not knocking the 300B or IBM, as both are capable of good results. However, neither guarantees good results when misapplied.
My experiments with SE amps suggested < 1 % at 5W is possible without feedback . I am unwilling to say the tricks I used as they took time and were not the cliched versions . They are all easy enough to work out . More importantly after many attempts I got the harmonics to reduce on a near exponential graph . The argument put up by Jean Hiraga in the 1980's was that the exponential curve seems to be of zero perceived distortion if the 2 nd doesn't exceed 1 % . His argument being that the the comparative harmonics please the ear and is taken to be neutral . He seems to argue that nothing except zero distortion would be taken to be as neutral . For example 0.05% 5 th and nothing else would be taken as less neutral . I suspect to make a 300 B or 211 version of my amp would not be difficult ( I have 77 V rms drive if required at > 10 mA ) . I did have 211 in mind . Conventional amps of this type usually are about 5 % THD if the religious route is taken ( sad that it is ) . The other valve I have just received is Gu 50 . These are called the poor mans 300 B by some .
Jardis is a strange word in French as the S is sounded , it means something like " once upon a time " or when time was .
I feel I do well for a man with almost zero interest in valves .
Jardis is a strange word in French as the S is sounded , it means something like " once upon a time " or when time was .
I feel I do well for a man with almost zero interest in valves .
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These are the days of perceived value.
High price is assumed to mean better, famous moniker also, and so forth. And it's not just audio, it's everywhere. If you own a say Kia hatchback, chances are you'll run up against at least one guy who will explain why your car is a moving pile of junk. But if you were to switch the monikers from Kia to say Porsche, your car would be revered without any additional change. Ditto TV set, ditto everything.
It's a shallow world out there. And it ain't getting better.
High price is assumed to mean better, famous moniker also, and so forth. And it's not just audio, it's everywhere. If you own a say Kia hatchback, chances are you'll run up against at least one guy who will explain why your car is a moving pile of junk. But if you were to switch the monikers from Kia to say Porsche, your car would be revered without any additional change. Ditto TV set, ditto everything.
It's a shallow world out there. And it ain't getting better.
"Nobody ever got fired for buying IBM", was the slogan they advertized with; straight for the guts. They planted this mneme of implicit trustworthiness with great succes.
Another great way IBM fjukked with the collective mind was the "Think" thing. I have always felt this was a misappropriation of Timothy Leary's "Think for yourself, question authority". They blanked out the bits obviously unacceptable to any power hungry organization, and by butchering Leary's slogan, they perversely snuck in the notion that to Think is what IBM does, and that you can safely leave it up to them.
I work on the 5% rule: 95% of human activity is rubbish - repetitive, mindless, ego-driven, ritualistic, fit only to be dropped into a shredder. But, that small 5% is where the action is, this is where the human race inches forward, fractional bit by fractional bit, so that after some time period one can actually look over one's shoulder and say, "Yes, we have made some progress there ..."
Frank
Frank
Note the 50Hz, many SET designs are entering core saturation at a few Watts below 100 Hz. The measurement at 1 kHz would be much better.
HiFi shows always seem to demo SET amps with tinkly piano and female vocals, not drums and bass
From memory my cheap and reasonable Danbury transformer gave 2W at 18 Hz 8 R . The output valve is KT 88 . At 50 Hz it will give 8W at about double the 1 kHz distortion . The graphs below are before I introduced any transistors to the mix . 2 valves , 8 R and good to about 50 kHz . No loop feedback . EL 34 was almost as good with nicer clipping spectrum . EL 34 mostly double the distortion at lower wattage's . Although in theory KT88 is more powerful , in practice there is not much in it . The EL34 is run hard to get that . The design was inspired by the PYE Mozart . In the end it had nothing in common with the PYE apart from SE . I tried the RH34 by Alex Kitic . I didn't get far with that . I did use an LM317 as a current sink for the EL 34 next . I had to work very hard to beat that .
This is the RH 88 I rejected . An interesting design which should beat the Jardis on measurements . The ECC81 allows it to function as intended due to high Rp . I did try all sorts of modifications and would say his design is ideal for what it set out to do . My own has better distortion and sensitivity for no more money . I think an EF184 in semi pentode would be better . EF184 is almost an ECC81 if triode . The idea is that the output valve functions as a pentode as far as drive is concerned . The Rp of the KT 88 is greatly lowered by anode to g1 feedback via Rfb 100 K . The ECC81 sort of blends in as it's impedance is high . One could say it becomes a super triode . A lot of effort has gone into throwing things away . There s no cathode capacitor on the ECC 81 , that is important and also means no quality of capacitor to debate . The KT88 can be triode connected . Results are about the same with lower sensitivity ( 30 % if I remember ) . What I like is the blocking cap is doing more than usual . If using an EF184 the same cap can offer shunt input feedback . One cap with 3 vital jobs .
Nige,
I wonder how that little dinky amp you posted above would sound if you dished out the extra money and effort to eliminate even that last capacitor by adding a DC servo?
If you went all grand about it, you could use an LF412 dual FET input op amp to control both tubes, working on the assumption that the best capacitor is the one not there.
Just musing ...
I wonder how that little dinky amp you posted above would sound if you dished out the extra money and effort to eliminate even that last capacitor by adding a DC servo?
If you went all grand about it, you could use an LF412 dual FET input op amp to control both tubes, working on the assumption that the best capacitor is the one not there.
Just musing ...
@wayne, john dozier
Yep, it's a good set of people here, all easy going, no strife, nobody is trying to prove his point at all costs - rare indeed.
Frankly, this is one of only two forums I go to, the other being a more local one, from Zagreb, Croatia; it has the added benefit of being 360 km (app. 220 miles) away from me, so I get to meet the people there in person, something I sorely miss here.
The other thing I do miss here is good, old Thorsten; I find his ideas intriguing and miss the discussions coming from them.
Yep, it's a good set of people here, all easy going, no strife, nobody is trying to prove his point at all costs - rare indeed.
Frankly, this is one of only two forums I go to, the other being a more local one, from Zagreb, Croatia; it has the added benefit of being 360 km (app. 220 miles) away from me, so I get to meet the people there in person, something I sorely miss here.
The other thing I do miss here is good, old Thorsten; I find his ideas intriguing and miss the discussions coming from them.
The famous pre 1939 Loftin White tackles that . TubeCad makes it safer .
The Tube Cad Journal: Design Idea-A safe Loftin-White amplifier
I honestly had no interest in valve amps a year ago . I don't love them espeailly now . They are great fun to play with . One thing it has helped me to understand is , what is amp and what is source . Mostly what I heard with a domestic grade of CD player would not justify a preference of valve over transistor . I would even dare to say identical would be the observation using an average CD player . What a condemnation of CD players . None of my amps are especially euphonic .
The 2A3 is a lovely valve . I have some Gu 50 which are clones of Telefunken LS50 . An interesting valve as it is a development of the Harries Valve company Beam Tetrode . Harries designed it in 1935 , RCA bought it and produced 6L6 ( or similar ) . 807 was not so special so plate to plate feedback was introduced to help tame it a bit ( as used by Alex Kitic in RH88 ) . In 1942 the Telefunken " Ray Pentode " LS 50 was introduced . Much like a KT 88 or 6550 ( EL 156 ) . Captured by the Soviets and cloned . The KT 88 was introduced Nov 56 ( me September ) . LS 50 is truly a milestone . said to be the better fake triode and able to run silly voltages .
These are the sources of information I found most informative
How to design valve guitar amplifiers
Patent Specification No. 496,083
http://www.clarisonus.com/Archives/TubeTheory/Schade 1938 Beam Power Tubes.pdf
Single-Ended Applications
+10 On Thorsten ...
Paul McGowan of Ps Audio fame got off on McIntosh when he got into not using Output transformers in SS Designs , basically he thought they were using it to skirt the FTC test , well along with all the negatives of having them there ...
Article : McIntosh transformers | PS Audio
Ironically a Mac501 amp failed to pass the 1 hr preconditioning test when JA attempted to test it ...
McIntosh MC501 monoblock power amplifier Measurements | Stereophile.com
The funny part is Mac owners believe theres an advantage to autoformers on the outputs of SS amps and while i will admit to being a mac fan and have owned their stuff over the years , there is no doubt to their limitations , weak drive and dark sounding , working at their best where power is required at 8 ohm , the autoformer allows them to cheat a bit by being able to provide high wattage at 8 ohms and not worry about load tolerance ...
Thoughts ...
Paul McGowan of Ps Audio fame got off on McIntosh when he got into not using Output transformers in SS Designs , basically he thought they were using it to skirt the FTC test , well along with all the negatives of having them there ...
Article : McIntosh transformers | PS Audio
Ironically a Mac501 amp failed to pass the 1 hr preconditioning test when JA attempted to test it ...
McIntosh MC501 monoblock power amplifier Measurements | Stereophile.com
The funny part is Mac owners believe theres an advantage to autoformers on the outputs of SS amps and while i will admit to being a mac fan and have owned their stuff over the years , there is no doubt to their limitations , weak drive and dark sounding , working at their best where power is required at 8 ohm , the autoformer allows them to cheat a bit by being able to provide high wattage at 8 ohms and not worry about load tolerance ...
Thoughts ...
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Auto transformer output has plenty to recommend it especially if one can access the direct output for 8 /4R . If the 1R tap is used any crossover distortion is reduced . My bet is nicer all round . In the the late 1970's I was invited by Sony to a show . There I saw a class D amp . The engineer said it had a nice sound not unlike valves . He reasoned the output choke was doing that . His words " now we understand it was the transformer we liked " . The amplifier was not produced , a range of conventional amps called Esprit instead .
BTW . 5.7 R was said to be an optimum power transfer resistance . Most 8 R speakers approximate to that . 16 R generally helps distortion in an AB amp . The 1 R tap used with an 8 R speaker should offer excellent performance . Class AB should be almost as class A if so . It is like having a gearbox . I love their amps , even more so now I know .
BTW . 5.7 R was said to be an optimum power transfer resistance . Most 8 R speakers approximate to that . 16 R generally helps distortion in an AB amp . The 1 R tap used with an 8 R speaker should offer excellent performance . Class AB should be almost as class A if so . It is like having a gearbox . I love their amps , even more so now I know .
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