Oh!... already concluded! 0 +20 +40 volts is the same as -20 0 +20
But are you using the current that Rodd suggested?
Do you think the input transistor is perfect to that low voltage over it, is it linear using that voltage Mike?
Also your output, is this transistor good to only 20 Volts from colector to emitter, are this unit working in its linear region?
The question is posted my dear friend Mike, because i also like this amplifier, one of the "references" of quality we can have, beeing a real JLH adapted. The standard JLH used some transistor alike 2N3055, and this unit "loves" to work with 2 or 3 ampères...and also is very happy when have 20 to 30 volts from colector to emitter, and also feel good when heat is around 30 watts each unit, because of that, that nice transistor unit, was used deeply as series power supply pass transistor.
I have some suspection, herr Bittner, that your amplifier can be even better using 2N3055...... a worst transistor, no doubts!...but match with the design.
Well Mike, i will say that you did not heard JLH yet!.... put the 2N3055 and the correct input....i think it is BC549C (not sure), and select one BD139 with lower gain, to match the old days... something alike 90 of gain.....in the place of 150 you may be using, put the current Rodd suggest and i think you will turn surprised....Yeahh!...i know this is stupid, change modern transistor by 2N3055?....but try it please.
There are some mistery in this universe that we have troubles to understand...this is one of them.
Also...put the damn condenser and non simetrical supply...an see the wonderfull colouration you will have.
I know colouration is not perfect Mike, but, if we go deep into the direction of the perfect sound, instead of searching the good sound.... the conclusion you will find, is that is much better to switch all those things off and change hobbie, and will be frustrated, as perfection do not exist in this universe...we are in an unstable stable world.
regards,
Carlos
But are you using the current that Rodd suggested?
Do you think the input transistor is perfect to that low voltage over it, is it linear using that voltage Mike?
Also your output, is this transistor good to only 20 Volts from colector to emitter, are this unit working in its linear region?
The question is posted my dear friend Mike, because i also like this amplifier, one of the "references" of quality we can have, beeing a real JLH adapted. The standard JLH used some transistor alike 2N3055, and this unit "loves" to work with 2 or 3 ampères...and also is very happy when have 20 to 30 volts from colector to emitter, and also feel good when heat is around 30 watts each unit, because of that, that nice transistor unit, was used deeply as series power supply pass transistor.
I have some suspection, herr Bittner, that your amplifier can be even better using 2N3055...... a worst transistor, no doubts!...but match with the design.
Well Mike, i will say that you did not heard JLH yet!.... put the 2N3055 and the correct input....i think it is BC549C (not sure), and select one BD139 with lower gain, to match the old days... something alike 90 of gain.....in the place of 150 you may be using, put the current Rodd suggest and i think you will turn surprised....Yeahh!...i know this is stupid, change modern transistor by 2N3055?....but try it please.
There are some mistery in this universe that we have troubles to understand...this is one of them.
Also...put the damn condenser and non simetrical supply...an see the wonderfull colouration you will have.
I know colouration is not perfect Mike, but, if we go deep into the direction of the perfect sound, instead of searching the good sound.... the conclusion you will find, is that is much better to switch all those things off and change hobbie, and will be frustrated, as perfection do not exist in this universe...we are in an unstable stable world.
regards,
Carlos
Hi Carlos !
Yes, i think you can make this JLH-type sound even nicer with
these old 2n3055, using outputcouplingcap and so on...
BUT, my problem with the DoZ/JLH is, i can't call this type of
amplifier HIFI... They do sound great, no doubt !
But they are FAR from exact reproduction...
And i really don't like the idea of an amp adding so much to the
music that it sounds totally nice, using the speakers as instrument,
not as reproductiondevice.
I made some tests/experiments, these showed that the DoZ does
not control the speakers, the speakers start to produce their own sound,
giving more volume into the sound, even higher efficiency...
I think this is the reason why these amps sound so powerful.
I would call the DoZ a perfect candidate for "nice sounding" amp !
Mike
Yes, i think you can make this JLH-type sound even nicer with
these old 2n3055, using outputcouplingcap and so on...
BUT, my problem with the DoZ/JLH is, i can't call this type of
amplifier HIFI... They do sound great, no doubt !
But they are FAR from exact reproduction...
And i really don't like the idea of an amp adding so much to the
music that it sounds totally nice, using the speakers as instrument,
not as reproductiondevice.
I made some tests/experiments, these showed that the DoZ does
not control the speakers, the speakers start to produce their own sound,
giving more volume into the sound, even higher efficiency...
I think this is the reason why these amps sound so powerful.
I would call the DoZ a perfect candidate for "nice sounding" amp !
Mike
Yes, a very good sounding amplifier, but not a precise amplifier.
I also can understand how extense and deep is your message, and also cannot dennie you may have enought reasons to say that.
Well, we are entering now inside some dark world....were nothing is guaranteed as good or bad....the subjectivity world...this world is so "bond shaking", that people invented a lot of IMD, IHF, harmonics Odds and not odd.... and crossover interdependence neutral transient reflexed density, and others complex terms that i am trying to decode till today, and having problems all the time to feel, or reach, sense over those things.
I have some fear....that the uncoloured, very precise amplifier, may sound terrible.
Well, herr Bittner, i am counting on you to show me that..... please!...change my mind related that...because all changes we can make in our mind, is "progress" to ourselves.
regards,
Carlos
I also can understand how extense and deep is your message, and also cannot dennie you may have enought reasons to say that.
Well, we are entering now inside some dark world....were nothing is guaranteed as good or bad....the subjectivity world...this world is so "bond shaking", that people invented a lot of IMD, IHF, harmonics Odds and not odd.... and crossover interdependence neutral transient reflexed density, and others complex terms that i am trying to decode till today, and having problems all the time to feel, or reach, sense over those things.
I have some fear....that the uncoloured, very precise amplifier, may sound terrible.
Well, herr Bittner, i am counting on you to show me that..... please!...change my mind related that...because all changes we can make in our mind, is "progress" to ourselves.
regards,
Carlos
The risk seems very big that a uncoloured precise amp sounds terrible.
And it seems unfair/difficult to directly compare one of these precise
amps with a DoZ, the DoZ will nearly always win, as it adds "niceness"
to the music.
But with very good recordings you start to realize that there is
"something" wrong when listening to the doz, as the good recording
does not need something added...
For example, in recordingstudio it would be VERY wrong to use a DoZ
as monitoring amp...
Mike
And it seems unfair/difficult to directly compare one of these precise
amps with a DoZ, the DoZ will nearly always win, as it adds "niceness"
to the music.
But with very good recordings you start to realize that there is
"something" wrong when listening to the doz, as the good recording
does not need something added...
For example, in recordingstudio it would be VERY wrong to use a DoZ
as monitoring amp...
Mike
I see now how...in part...he got away with it.
The stock DoZ uses a 470µf cap on the wiper of the offset pot. With the cap-coupled amp, it charges very slowly to keep from any turn-on thumps. It also causes the top NPN output device to have over twice the 'Q' current through it at startup until the cap gets charged and things settle down.
Still, the gain of a single transistor at the input causes to much DC drift for me. I like to see less than +/-3mV drift, and I don't think it can be done without a servo.
MikeB...did you use the 'standard' values of 100K for the pots? And I also see no zener stabilization.
I would say that there is nothing at all wrong with the sound. My own measurements?
THD+N: 0.1% @ 19.5W/ch
Full Power Bandwidth, +/-3db (8 ohms): 5Hz - 96KHz
S/N Ratio (A-Weighted): 96db
Wish I could measure IM, but my gear won't do it. As it is, not a thing wrong with those figures.
Attached is my own schematic...
The stock DoZ uses a 470µf cap on the wiper of the offset pot. With the cap-coupled amp, it charges very slowly to keep from any turn-on thumps. It also causes the top NPN output device to have over twice the 'Q' current through it at startup until the cap gets charged and things settle down.
Still, the gain of a single transistor at the input causes to much DC drift for me. I like to see less than +/-3mV drift, and I don't think it can be done without a servo.
MikeB...did you use the 'standard' values of 100K for the pots? And I also see no zener stabilization.
I would say that there is nothing at all wrong with the sound. My own measurements?
THD+N: 0.1% @ 19.5W/ch
Full Power Bandwidth, +/-3db (8 ohms): 5Hz - 96KHz
S/N Ratio (A-Weighted): 96db
Wish I could measure IM, but my gear won't do it. As it is, not a thing wrong with those figures.
Attached is my own schematic...
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