This reminds me of an event in the early 70ies. The folks at Yamaha had made up their mind to make a reference guitar amp. They did, it was announced and a selling date was established. The first day, there was literally a cue of people waiting to buy it; the second day, half of the first day, and by day four, sales had stopped altogether.
Obviously, this caused Condition Red at Yamaha. Two engineers from the project were quickly dispatched to L.A. to what was going on. It took them two weeks to get to the bottom of it, but they did.
The next model of the same amp actually included a pot marked "Distortion". It turned out that most rock guitar players didn't give a damn about low distortion and whatnot, they wanted "the sound", and the only way to get it was to enable them to distort the guitar as they saw fit.
Not to defend or attack anyone, but I must admit that you can get some really cool sound from a distorted guitar, especially the bass guitar. And in the late 60ies, London and L.A. were the places to be.
It is something new to me, about distorted bass guitar. Working with musicians I found that bass guitarists prefer as clean as possible amps. Lead guitar is a different story. It lacks of character, so increased with loudness distortions help to express emotions better.
Speaking of distortions, Roland made best pedals for this purpose. I did something similar, but my prototype had a real pedal to control overdrive by foot, from clean to very dirty sound. It was made of a filter that attenuated fundamentals and boosted harmonics combined with asymmetric logarithmic amp, then symmetric exponential amp and another EQ.
First I used matrixes made of Germanium diodes and resistors, then found that diodes without resistors sound Ok. Then found schematic of Roland pedal and surprised how similar it was.
Speaking of distortions, Roland made best pedals for this purpose. I did something similar, but my prototype had a real pedal to control overdrive by foot, from clean to very dirty sound. It was made of a filter that attenuated fundamentals and boosted harmonics combined with asymmetric logarithmic amp, then symmetric exponential amp and another EQ.
First I used matrixes made of Germanium diodes and resistors, then found that diodes without resistors sound Ok. Then found schematic of Roland pedal and surprised how similar it was.
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Wave, I distinctly remember reading about the whole case in the early 70ies, which was, after all, at least 37 years ago, I honestly don't remember where. It must have been a magazine, no Internet way back then.
Also, I am told that tastes change over time, and 37 years is quite some time.
Also, I am told that tastes change over time, and 37 years is quite some time.
You are right. Tastes change. Blues guitarists used slight distortions: their guitars were semi-acoustic and guitarists could express emotions without heavy distortions. Rock guitars were wooden, so needed more pronounced spectrum dependence on loudness added. Heavy metal is further "improvement", since all is compressed and no dynamics is needed from guitar.
I've been wondering for some time - has anyone here tried building a transistor output stage by using say one predriver, but instead of having one driver, using the same device for EACH of the output transistors, with a base resistor on the driver and a smallish value resistor from the emitter to base of the power device?
Effectively making a discrete Darlington transistor?
Any experiences? Any thoughts? Any tangible gains, above the level of academic?
Effectively making a discrete Darlington transistor?
Any experiences? Any thoughts? Any tangible gains, above the level of academic?
Hi Wavebourne . Interesting what you say . The example I was looking at was all ECC82 in Valve Wizard . The hybrid was my idea . I have some 12BH7A also which look great on scope . I did note the recommendation to respect maximum cathode voltages . I was having this same discussion about DI boxes ( Direct injection, for example bass guitar to mic input with ground lift ) . My friend wanted pentode sound . I suggested a cascode with singe triode option ( SRPP perhaps ) . Some guitarist use a Morph control with lets say an EF184 pentode . The 184 becomes an ECC81 approximately if going to full triode . The Morph circuit I suspect does find the Ultra-linear point of the pentode ? I am far more fussy about valves than op amps . Different valves are more obviously different than most sensible op amps , even valves with the same type numbers ( most ECC 82 measure about the same , none sound the same ) . Sure op amps sound different . Most never sound quite right to me regardless how how much I spend . OPA 604 and 2604 seem reference points , price is good .
A general question . Quad used 0.5 Vrms for full output . I have even used 0.25 V with superb results ( and passive preamp , 100 W output ) . My little valve amp is about 2.79 V . I am fitting a gain stage . However my instinct is to say that's the job of the pre amp . Most of the valve preamp's have the capacity to go to 3 V . Any observations gratefully received . I do suspect 0.5 V is ideal . My 100 W amp has very low distortion extending up to 100 kHz , setting the gain to 100 did not harm it . In fact the reverse . I feel the distortion was far too low to say I like distortion B rather than A ( lower gain ) . What I was hearing was genuinely better sound . My hypothesis is that long before the Nyquist instability point is reached the amplifier starts to show symptoms . Some say about up-scaling distortion harmonics as one possible reason ( 7 th and 9 th ) .
Many have been producing very low distortion amps as a challenge . I wouldn't mind betting that they are happy with them because there is no obvious problem . Our dear friend NE5534 is an example . Op amps are power amps , especially 5534 . I was asked to provide a MC preamp with a gain of 2000 at 1kHz ( clone of 5534 by a different number and lower current ) . This required the first op amp to have a gain of 125 at 1 kHz ( I was too lazy to do a redesign so just increased the first stage ) . I have to say it was magical . The MM version whilst nice enough was more enclosed sonically . The distortion was still 0.1 % if memory serves me correctly . Hiss was about > -66 dB weighted .
A general question . Quad used 0.5 Vrms for full output . I have even used 0.25 V with superb results ( and passive preamp , 100 W output ) . My little valve amp is about 2.79 V . I am fitting a gain stage . However my instinct is to say that's the job of the pre amp . Most of the valve preamp's have the capacity to go to 3 V . Any observations gratefully received . I do suspect 0.5 V is ideal . My 100 W amp has very low distortion extending up to 100 kHz , setting the gain to 100 did not harm it . In fact the reverse . I feel the distortion was far too low to say I like distortion B rather than A ( lower gain ) . What I was hearing was genuinely better sound . My hypothesis is that long before the Nyquist instability point is reached the amplifier starts to show symptoms . Some say about up-scaling distortion harmonics as one possible reason ( 7 th and 9 th ) .
Many have been producing very low distortion amps as a challenge . I wouldn't mind betting that they are happy with them because there is no obvious problem . Our dear friend NE5534 is an example . Op amps are power amps , especially 5534 . I was asked to provide a MC preamp with a gain of 2000 at 1kHz ( clone of 5534 by a different number and lower current ) . This required the first op amp to have a gain of 125 at 1 kHz ( I was too lazy to do a redesign so just increased the first stage ) . I have to say it was magical . The MM version whilst nice enough was more enclosed sonically . The distortion was still 0.1 % if memory serves me correctly . Hiss was about > -66 dB weighted .
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Well Wavey, you didn't bite, so I'll give you the answer.
One fellow who brought by an expensive preamp with metal knobs was not happy with it. Turns out the potentiometers were mounted to a PC card and went through plastic bushings on the front panel. When he walked across the carpet to change things he often heard a loud pop.
Changing to non conductive knobs not only solved that problem, but also reduced the EMI being conducted into the case.
So although there are silly claims often made, there can always be a case where the results actually happen and for a well understood reason.
Now after he spent all that money do you think he would have been happy with cheap plastic knobs?
DNM believe in as little metal as possible especially if magnetic . Stainless steel is less magnetic and can be bought as non magnetic grade . My phono stage housed in a wooden box did seem to sound better . The metal box never shielded it much anyway . Wooden knobs ? I would if you will forgive the pun . DNM pre amps were always a favourite of mine . The capacitors are excellent value .
Anyone every used Danbury's SE transformers ?
DNM Design Principles, Page 3 of 5 - Materials Technology
Anyone every used Danbury's SE transformers ?
DNM Design Principles, Page 3 of 5 - Materials Technology
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Sounds more like an ESD problem, which should be addressed by clamping diodes and a low impedance path to GND and a power plane.
Hope for this guy there's no structural damage in one of the semiconductors..
Of course it was a vacuum tube preamp (6DJ8 as I recall) and grounding the shafts caused a hum issue. So without the worry of damaging semiconductors the wood knobs were a decent solution.
Grounding shafts caused a hum issue?
I would hesitate to call such design "a decent solution".
Wave, that's a problem which is all but unknown. Taking a leap here, but I think that's one of the reasons why the DIN 45500 standard never really left Germany, because they insisted on relatively small voltages and relatively high input impedances, like 470k.
Many went for all of 1 Mega Ohm, and not surprisingy, there were all sorts of problems and issues. Touching a metal pot end, be it volume or whatever, was not unknown to cause hum or worse (not like it was a daily occurence, but it did happen here and there). There's a reason why the German audio industry was so (hell bent) keen on sliders with plastic ends and plastic buttons.
Many went for all of 1 Mega Ohm, and not surprisingy, there were all sorts of problems and issues. Touching a metal pot end, be it volume or whatever, was not unknown to cause hum or worse (not like it was a daily occurence, but it did happen here and there). There's a reason why the German audio industry was so (hell bent) keen on sliders with plastic ends and plastic buttons.
DVV . Your thoughts on DIN45500 and related subjects ? For a start , cheap Preh DIN plugs are vastly superior to the majority of RCA . Also with the proviso that the distortion is in exponential decent or just 2nd harmonic 8 watts 1 % distortion and able to drive 4 ohms seems good to me and is still my acceptance level for true hi fi . If I want lower distortion first I buy some Quad 63's . Crossover distortion is not acceptable if avoidable . 8 W class A , 64 W 4 ohms class AB looks good to me .
My big surprise from DIN is how much I find high impedance feeding low works well . Equally how low feeding high as is usual works well ( RCA ) . When it gets to one to one I have doubts ( or is it saying the design is week ? ) . For RF and power transmission it is desirable ( trans-conductance ) . I also notice much of DIN would work with RCA , I never looked to see if it was truly DIN if so . Was it 1mA into 1 K or something ? It resembled current drive speakers a bit . No idea as it never touched my life except when trying to get a tape deck to work , which usually it did . We didn't have the internet then and I am too lazy to Google it now . No use if I did as it isn't like the old days . Wikipedia at best mostly .
Talking mildly related subjects . I was asked to repair a 1950's Grundig tape recorder . It had an electrostatic mic ( not a condenser to my way of thinking ) . It's fidelity I would place in the highest order . The microphone recorded bird song like no other . This was the standard issue mic and not some fancy Neumann . It also had cotton backed belts . One day Ivor will give the LP12 the belt it deserves . Linn tried to sell me a Keel chassis ( Trevor ) , I was the only one at a show who in seconds could say it was better and why . I also said I could knock it up in an afternoon myself very quietly . I think I will uprate my LP12 . One piece of advice with LP12's . Voltage matters most , ultimately the motor is not good enough by a long distance . The only motor that springs to mind that is easily better is the Papst used in the Mitchell in the past . An induction motor certainly would be worth thinking of ( mini 8 pole if one exists , Kenwood 1033 , Pioneer PL12D worth a try for a 4 pole ) . Induction motors live in an adjacent family to synchronous and stepper . A lightly loaded induction has synchronous properties . What it doesn't have is notches . The magnetic field is elastic almost ( constant slip ) .
I came to a definitive statement or amps and devices to my own way of thinking . They are very different things . If I didn't design the device I have almost zero interest in it . It works or it doesn't work . If I need a special drill , I buy a special drill . I do not use special drills for aluminum . For example I was designing a filter the other day . It needed a GBP of 40 MHz , I had to redesign the filter as I didn't want to spend the money . The topology is 90% of the design . The best components in bad topology = bad amplifier . How many amplifiers are bad ? Most including most of mine I would imagine ? Somebody said many designs are " as flash as a rat with a gold tooth " . I know an engineer who designed almost the ultimate bearing , no one noticed ( 200 Rockwell hardness , I guess LP12 to be 64 which is fine , Garrard was 55 with 6 micron finish , Hacksaw blades about 85 ) . If it was an op amp we would be talking about it . It wasn't me if asking . I like mechanical engineering , it works or it doesn't . Also I find mechanical engineers very challenging . They will refuse to make something if they don't believe you are right . They tend to be very conservative . Often they prove themselves to be right . For example surface finish on bearings is irrelevant if better than 6 micron . We do better because we can and it looks nice . The bearing shell gap is generous to avoid drag ( very generous , not microns ) . The contact is minimal . I have to tell my engineer because it looks nice for him to do it . Then he is very proud of his work . Rightly or wrongly the customer often will look . When some turntable designer says it sound better I will use a rude word . I have proved that . A ridged bearing works best . It was very accurate in oval and bottom squareness ( 1/10 000 inch to 90 degrees . LP12 is concentric to <1/10 000 inch also , a good bearing ) .
Some people will look at a Garrard bearing and start modifying it . It is only is 55 Rockwell so soon degrades . It is not defective design , used as intended it will last 50 years plus . A posh 401 bearing ( posh looking and same parts ) did - 78 dB rumble . I would say that was still motor as it is an idler drive . Whilst my motor I designed is very good it is not perfect . I would guess the Garrard bearing is far more perfect than people guess . I place a very big emphasis on guess .
The DIN 45500 standard stipulated 4 Ohms as the loudspeaker load. Consequently, most German made amps had much lower power than competing Japanese amps, but incomparably better drive capability, as many were deisgned for TWO parallel pairs of speakers. Meaning 2 Ohms. A number the Japanese mass manufacturers can only dream of.
As a result, your average Grundig (considered as the El Cheapo brand in Germany) will generally play MUCH nicer sounding music than the vast majority of much more expensive and elaborate Japanese designs. And its objective lack of serious power will go by unnoticed - no matter what anyone says, those people knew how to get the right sound every time. And their insides were light years ahead of Japanese competitors, open them up and be prepared to be shocked - this kind of workmanship for such a low price?
Now imagine what the really serious German brands were making, people like ASC, LAS, Restek, etc.
This drive impetus is what always set the German products apart from the rest, and the only mass produced product outside Germany which has this trait are the Harman/Kardon amps, which throw in more as well. A shining example would be HK 680 integrated amp from 1999. It has an immediacy not often found anywhere, for any money. It seems to be having great fun while working at even stressful levels. It gives you that subjective feeling that it has oodles of power, way more than its specs would suggest.
For the spec freaks, and today, of course that the DIN 45500 set of standards looks ridiculously loose, and with regard to technology and the progress made since they were last updated, they ARE ridiculously loose. However, even listening to product barely satisfying those ancient standards, one is often surprised how well that sounds nevertheless.
Because of this appearent dichotomy, I have long ago stopped caring much for the standaards and the specs, but simply rely on my own ears. If I like, I couldn't give a hoot about standards, and if I don't, I don't care if it satisfies NASA's standards.
As a result, your average Grundig (considered as the El Cheapo brand in Germany) will generally play MUCH nicer sounding music than the vast majority of much more expensive and elaborate Japanese designs. And its objective lack of serious power will go by unnoticed - no matter what anyone says, those people knew how to get the right sound every time. And their insides were light years ahead of Japanese competitors, open them up and be prepared to be shocked - this kind of workmanship for such a low price?
Now imagine what the really serious German brands were making, people like ASC, LAS, Restek, etc.
This drive impetus is what always set the German products apart from the rest, and the only mass produced product outside Germany which has this trait are the Harman/Kardon amps, which throw in more as well. A shining example would be HK 680 integrated amp from 1999. It has an immediacy not often found anywhere, for any money. It seems to be having great fun while working at even stressful levels. It gives you that subjective feeling that it has oodles of power, way more than its specs would suggest.
For the spec freaks, and today, of course that the DIN 45500 set of standards looks ridiculously loose, and with regard to technology and the progress made since they were last updated, they ARE ridiculously loose. However, even listening to product barely satisfying those ancient standards, one is often surprised how well that sounds nevertheless.
Because of this appearent dichotomy, I have long ago stopped caring much for the standaards and the specs, but simply rely on my own ears. If I like, I couldn't give a hoot about standards, and if I don't, I don't care if it satisfies NASA's standards.
DVV . Thanks for that . It sort of says marketing men took the ball away form the Germans .
My amp competition has a new rule . All amps must reach DIN45500 .
That would allow 10 % distortion at 100 Watts if a person thought it OK . As this is a competition that is the choice of the designer . The listening tests would be blind so no prejudice about outcome . There would have to be a technical elimination . I would not allow an amp which might damage a tweeter .
The more I think about it topology and device is a different subject . There comes a point where a device is not good enough . This is judged by failure or uncomfortable sound . I got my cemetery of op amps from a lady friend of mine who was upgrading a phono stage . The design was highly competent and had good reviews ( about $700 ) .
She found my more modest design always sounded better . This is what needs to be firmly explained . Newcomers will find they can buy the best of everything and still have a mediocre design . I learnt everything from 23 years of repairing . I noticed conflicting principles often sounded equally wonderful . The designers would not be able to agree on topology . Their ears have lead then to similar outcomes . I notice a few things which were always the same . Excellent power supplies and choice of passive devices . I wish I could say I have become an expert . I still learn every day . I became a minimalist as the best capacitor is no capacitor . I like JFET's only because they avoid the use of capacitors . That means I use them out of that prejudiced alone . On paper a bipolar with emitter resistor is more linear and better gm . However it needs current and that requires a capacitor to be fitted very often ( not always , ears used please , DC offset is half of the story ) .
My amp competition has a new rule . All amps must reach DIN45500 .
That would allow 10 % distortion at 100 Watts if a person thought it OK . As this is a competition that is the choice of the designer . The listening tests would be blind so no prejudice about outcome . There would have to be a technical elimination . I would not allow an amp which might damage a tweeter .
The more I think about it topology and device is a different subject . There comes a point where a device is not good enough . This is judged by failure or uncomfortable sound . I got my cemetery of op amps from a lady friend of mine who was upgrading a phono stage . The design was highly competent and had good reviews ( about $700 ) .
She found my more modest design always sounded better . This is what needs to be firmly explained . Newcomers will find they can buy the best of everything and still have a mediocre design . I learnt everything from 23 years of repairing . I noticed conflicting principles often sounded equally wonderful . The designers would not be able to agree on topology . Their ears have lead then to similar outcomes . I notice a few things which were always the same . Excellent power supplies and choice of passive devices . I wish I could say I have become an expert . I still learn every day . I became a minimalist as the best capacitor is no capacitor . I like JFET's only because they avoid the use of capacitors . That means I use them out of that prejudiced alone . On paper a bipolar with emitter resistor is more linear and better gm . However it needs current and that requires a capacitor to be fitted very often ( not always , ears used please , DC offset is half of the story ) .
Agreed, Nigel. Germans were always good to excellent regarding the technology itself, but absolute dummies when it came to selling. Exactly the same as Philips. They are also not simply stubborn, but downright obstinate in their insestence that they do it better than everybody else.
I am not trying to insult anyone here, I am simply stating facts as I see them. I have much respect for the Germans, but I cannot refuse to see what they are doing wrong. Ultimately, what's left of the Grman audio industry? Very few old companies, only those who realized in good time that blind faith in DIN 45500 standards and nothing else is a road to perdition.
That's why even what little is left of German companies is now generally owned by someone else. The German electronics giant, Grundig, is now wholly owned by Philips, as is Loewe Opta, now making a comeback with some truly stunning TV sets. Uher, the Munich company famous for its portable tape recorders, is owned by Harman International, as is Becker (Germany's largest car entertainment manufacturer), reVox, Switzerland and Germany's Studer (had factories in both countries), Austra's AKG, Koerting was bought out by Slovenia's Gorenje in 1986, and many large and small brands have just disappeared altogether (ASC, LAS, Perpetuum Ebner, Dual, etc).
I understand that Perpetuum Ebner (PE), a very old company driven out of TT business by their down the street (literally) competitor Dual Steidinger GmbH, is today bigger than ever, but thanks to the fact that they turned to trading and abandoned audio.
Other German companies of world repute, such as AEG, Telefunken and Bosch, are now owned by Siemens - at least, they stayed at home in that respect.
Philips is, thank God, still their own boss.
Left standing are small and medium sized companies, most notably T+A, Restek, Thorens, Elac, Kirksaetter, and a few others.
I am not trying to insult anyone here, I am simply stating facts as I see them. I have much respect for the Germans, but I cannot refuse to see what they are doing wrong. Ultimately, what's left of the Grman audio industry? Very few old companies, only those who realized in good time that blind faith in DIN 45500 standards and nothing else is a road to perdition.
That's why even what little is left of German companies is now generally owned by someone else. The German electronics giant, Grundig, is now wholly owned by Philips, as is Loewe Opta, now making a comeback with some truly stunning TV sets. Uher, the Munich company famous for its portable tape recorders, is owned by Harman International, as is Becker (Germany's largest car entertainment manufacturer), reVox, Switzerland and Germany's Studer (had factories in both countries), Austra's AKG, Koerting was bought out by Slovenia's Gorenje in 1986, and many large and small brands have just disappeared altogether (ASC, LAS, Perpetuum Ebner, Dual, etc).
I understand that Perpetuum Ebner (PE), a very old company driven out of TT business by their down the street (literally) competitor Dual Steidinger GmbH, is today bigger than ever, but thanks to the fact that they turned to trading and abandoned audio.
Other German companies of world repute, such as AEG, Telefunken and Bosch, are now owned by Siemens - at least, they stayed at home in that respect.
Philips is, thank God, still their own boss.
Left standing are small and medium sized companies, most notably T+A, Restek, Thorens, Elac, Kirksaetter, and a few others.
Funny ,
Never heard good sounding German hi-FI until recent years and guess which cars had or may still have the worst sounding audio systems in Dah world ..
Music culture goes along way IMO , the japs never understood this , their music doesn't demand such , rock and roll, disco, r&b, jazz, reggae, et al requires some jump. Germans who like to boogie bought American ..
Hence mericans always had big amplifers , most euro and jap amplifiers (there were some exceptions sansui BA 5000) allow you to load up speakers , so always passed ..
My 2c..
Never heard good sounding German hi-FI until recent years and guess which cars had or may still have the worst sounding audio systems in Dah world ..
Music culture goes along way IMO , the japs never understood this , their music doesn't demand such , rock and roll, disco, r&b, jazz, reggae, et al requires some jump. Germans who like to boogie bought American ..
Hence mericans always had big amplifers , most euro and jap amplifiers (there were some exceptions sansui BA 5000) allow you to load up speakers , so always passed ..
My 2c..
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