Sorry, I was in Bermuda.
The rationale for active current sources is mostly efficiency.
With active current sources such as the Penultimate Zen
and upcoming SOZ variations, we can start approaching 50%
efficiency instead of 5%.
That aside, I also prefer passives (even the occasional
light bulb). 🙂
The rationale for active current sources is mostly efficiency.
With active current sources such as the Penultimate Zen
and upcoming SOZ variations, we can start approaching 50%
efficiency instead of 5%.
That aside, I also prefer passives (even the occasional
light bulb). 🙂
Member
Joined 2002
Not many KNOW Nelson
equipment
😕
fotenote:
only GO(O)D KNOWWWWWWSSSSSS
But light bulbs can IandI use in HIFINelson Pass said:
equipment
😕
fotenote:
only GO(O)D KNOWWWWWWSSSSSS
SOZ Question
I am building a small SOZ with an active current source and 8 ohm
load resistors with 12 volt rails. Is there any way to calculate the
damping factor in paticular will the damping factor be different
with a active current sourse instead of using the source resistors.
Thanks Bob12345678 AKA Woody
I am building a small SOZ with an active current source and 8 ohm
load resistors with 12 volt rails. Is there any way to calculate the
damping factor in paticular will the damping factor be different
with a active current sourse instead of using the source resistors.
Thanks Bob12345678 AKA Woody
Damping factor
The damping factor of the amplifier will change changing R1 and R2 values. Or adding feedback.
The damping factor of the amplifier will change changing R1 and R2 values. Or adding feedback.
Thanks for the reply but the question still stands how can this
damping factor be calculated.
Regards, bob12345678 AKA Woody
damping factor be calculated.
Regards, bob12345678 AKA Woody
The output load divided by the sum of the Drain
resistors is the damping factor, which in this case
is 8 / (8+8) = .5
resistors is the damping factor, which in this case
is 8 / (8+8) = .5
Thanks for the responce a damping factor of .5 will work out
just about right for my plans. Building a 4 0r 5 watt SOZ in a
Dynaco st400 chassis I am almost tempted to use batteries!
Thanks Bob12345678 AKA Woody
just about right for my plans. Building a 4 0r 5 watt SOZ in a
Dynaco st400 chassis I am almost tempted to use batteries!
Thanks Bob12345678 AKA Woody
I made the X-SOZ
Based on Ian's circuit, I modify my SOZ into a x-SOZ today.
Power supply rail is +/-15V, I keep the 8 ohm drain resistors, removing all the 1 ohm power resistors, adding the 10k/1k feedback resistors, and the 15k bias resistor connecting to the Gate node.
a 2.2uF input coupling capacitor as the Gate is no longer at 0V.
all done within 2 hours.
result - hard to describe. definitely more details compared to SOZ. seems to sound sweeter, but apparently the dynamics is less than the SOZ. more audition is needed to draw a better conclusion.
Based on Ian's circuit, I modify my SOZ into a x-SOZ today.
Power supply rail is +/-15V, I keep the 8 ohm drain resistors, removing all the 1 ohm power resistors, adding the 10k/1k feedback resistors, and the 15k bias resistor connecting to the Gate node.
a 2.2uF input coupling capacitor as the Gate is no longer at 0V.
all done within 2 hours.
result - hard to describe. definitely more details compared to SOZ. seems to sound sweeter, but apparently the dynamics is less than the SOZ. more audition is needed to draw a better conclusion.
X Circuit Benefits
I have some questions on what X circuit topology offers. From what I understand one benefit is to lower the distortion of the output mosfets. Does X also help clean up power supply noise? Or, improve low impedance speaker performance? Finally are there other benefits that I have not touched on?
Thanks in advance.
I have some questions on what X circuit topology offers. From what I understand one benefit is to lower the distortion of the output mosfets. Does X also help clean up power supply noise? Or, improve low impedance speaker performance? Finally are there other benefits that I have not touched on?
Thanks in advance.
X works to create a more perfect match between the 2 halves of the circuit. Due to cancellation the increased matching will reduce noise and distorsion . With active current sources I think you can go on with a higher damping factor.
Stefano
Stefano
You can get arbitrarily greater damping factors
with the X amps, particularly if you enclose the
output stage in the loop.
One point is worth making here, and that is that the
SuperSymmetric circuit is not very forgiving of excess
feedback, tending to form an "infinite hall of mirrors"
with large open loop gain.
Thus it is quite ideal for simple circuits - 2 gain stages
or less being preferred.
When I first developed the idea, I couldn't get it to
work properly for a long time, which is why the Alephs
were released first. Later, when the Alephs were
reduced to 2 gain stage designs, I went back at the
X circuit, and it began working beautifully.
with the X amps, particularly if you enclose the
output stage in the loop.
One point is worth making here, and that is that the
SuperSymmetric circuit is not very forgiving of excess
feedback, tending to form an "infinite hall of mirrors"
with large open loop gain.
Thus it is quite ideal for simple circuits - 2 gain stages
or less being preferred.
When I first developed the idea, I couldn't get it to
work properly for a long time, which is why the Alephs
were released first. Later, when the Alephs were
reduced to 2 gain stage designs, I went back at the
X circuit, and it began working beautifully.
SOZ modyfied to X_SOZ
I did it today, an acording to the attached scematic, but only as a test.
I will try to describe my first impression of this X-SOZ:
The bas is more tight, grainy and dynamic and still deep.
The trebele is even more transparet and detaild.
The midtone more detailed.
The allover dynamics is increesed.
This is a conclusion after listening to two of my favortes.
First, Leonard Choen´s "Ten New Songs" (CD). For instance on the number "Alexander leaving" there is a butiful welldefined space around the voices which gives a nice impression of their presence. These voises is very much alive in a space made soft and wide by bas and synthesizer-violin(s) with deep drums and some sharp highhat. Nice composition.
Last, one of my old favortis, Tom Verlaine, an especially "Flash Light" from 1987 (LP). This is Rockn´roll without any soft edges with two leadguitars, bas and drums. This music needs a lot of dynamics, and no matter how "noisy" and complex the music seems to bee, you can still hear evrey single instrument on the stage. This album include some of the best Rockn´roll guitars I have ever heard, there is a lot of energy and a lot of fantasy here.
The improvements is clear, but it is not a totally different amplifire, it has just become a little (how much is that?) better. May be it will be even better when I make these changes with parts of a quality as the rest of the amplifire.
I did it today, an acording to the attached scematic, but only as a test.
I will try to describe my first impression of this X-SOZ:
The bas is more tight, grainy and dynamic and still deep.
The trebele is even more transparet and detaild.
The midtone more detailed.
The allover dynamics is increesed.
This is a conclusion after listening to two of my favortes.
First, Leonard Choen´s "Ten New Songs" (CD). For instance on the number "Alexander leaving" there is a butiful welldefined space around the voices which gives a nice impression of their presence. These voises is very much alive in a space made soft and wide by bas and synthesizer-violin(s) with deep drums and some sharp highhat. Nice composition.
Last, one of my old favortis, Tom Verlaine, an especially "Flash Light" from 1987 (LP). This is Rockn´roll without any soft edges with two leadguitars, bas and drums. This music needs a lot of dynamics, and no matter how "noisy" and complex the music seems to bee, you can still hear evrey single instrument on the stage. This album include some of the best Rockn´roll guitars I have ever heard, there is a lot of energy and a lot of fantasy here.
The improvements is clear, but it is not a totally different amplifire, it has just become a little (how much is that?) better. May be it will be even better when I make these changes with parts of a quality as the rest of the amplifire.
Attachments
Mr pass , I notice your posts regarding SS circuits .
So , I have a question.
Does that circuit with 2 diff pair ( this thread ) suffer the effect of
" hall of mirrors " ?
Thanks
So , I have a question.
Does that circuit with 2 diff pair ( this thread ) suffer the effect of
" hall of mirrors " ?
Thanks
Henrik,
The resistor that ties the drains of the mosfets together is that 15k ohms? How was the value calculated?
The 47u capacitors what voltage and how did you arrive at the capacitance value of these?
Also, R12 and R13 how was the value calculated?
Finally, the round symbols labled with "V" these are test points? Where V4 is 19 volts?
I have a similar SOZ and was considering converting it. Now that you have listened longer to the the X-SOZ. Do you feel the change is for the better?
Thanks in advance.
The resistor that ties the drains of the mosfets together is that 15k ohms? How was the value calculated?
The 47u capacitors what voltage and how did you arrive at the capacitance value of these?
Also, R12 and R13 how was the value calculated?
Finally, the round symbols labled with "V" these are test points? Where V4 is 19 volts?
I have a similar SOZ and was considering converting it. Now that you have listened longer to the the X-SOZ. Do you feel the change is for the better?
Thanks in advance.
Gnomus
R6, R7, R8, R9 are simple leftovers from the org. SOZ, and they now constitute a single resistor at 4E25. They are currentsources for the diff. pair.
C4, and R11+R13 forms a 1 Hz Highpass filter.
C=(1/(2*PI*R*f*1000000)) uF.
Frequences from the input under 1 Hz wil go to the output in openloopgain.
The calculation of R13 an R14 was made by Ian.
R11 and R13 divides the outputsignal, and R14 increases the source (preamp) impedance to allow the inputsignal to swing with the feedbacksignal.
This is my understanding, but may be there is more to this.
Other values could be used, but since these works fine, i will let them stay.
V2 an V4 is the powersupply at 19V each.
V1 and V3 is the inputsignal to simulate.
My X-SOZ still sounds good.
To do a test is very simple, so try it out and se if this is something for you.
Then let us hear how it suits you.
R6, R7, R8, R9 are simple leftovers from the org. SOZ, and they now constitute a single resistor at 4E25. They are currentsources for the diff. pair.
C4, and R11+R13 forms a 1 Hz Highpass filter.
C=(1/(2*PI*R*f*1000000)) uF.
Frequences from the input under 1 Hz wil go to the output in openloopgain.
The calculation of R13 an R14 was made by Ian.
R11 and R13 divides the outputsignal, and R14 increases the source (preamp) impedance to allow the inputsignal to swing with the feedbacksignal.
This is my understanding, but may be there is more to this.
Other values could be used, but since these works fine, i will let them stay.
V2 an V4 is the powersupply at 19V each.
V1 and V3 is the inputsignal to simulate.
My X-SOZ still sounds good.
To do a test is very simple, so try it out and se if this is something for you.
Then let us hear how it suits you.
Calculation of R13 and R14
As Henrik says, this calculation is not difficult. Basically the ratio determines the gain, i.e. the gain of each half of the diff pair is R13/R14 although this will be reduced due the intrinsic gain being quite low. The absolute values of these resistors are not critical but R14 determines the input impedance (single ended) and hence a low value will make life hard for the preamp driving it. On the other hand, too high a value will significantly reduce the high frequency roll off. The values I chose were intended as a compromise between these conditions.
Ian.
As Henrik says, this calculation is not difficult. Basically the ratio determines the gain, i.e. the gain of each half of the diff pair is R13/R14 although this will be reduced due the intrinsic gain being quite low. The absolute values of these resistors are not critical but R14 determines the input impedance (single ended) and hence a low value will make life hard for the preamp driving it. On the other hand, too high a value will significantly reduce the high frequency roll off. The values I chose were intended as a compromise between these conditions.
Ian.
High frequency roll off
Ian
With R13=10k and R14=1k (your choise) High roll off is 45kHz (-3db.
With R13=100k and R14=10k High roll off is 6kHz (-3db).
With R13=1k and R14=100E High roll off is 200kHz (-3db).
45kHz Seems to be a good choise, but woud´nt it be a little too hard job for some preamps to drive an impedance at 1k?
Ian
With R13=10k and R14=1k (your choise) High roll off is 45kHz (-3db.
With R13=100k and R14=10k High roll off is 6kHz (-3db).
With R13=1k and R14=100E High roll off is 200kHz (-3db).
45kHz Seems to be a good choise, but woud´nt it be a little too hard job for some preamps to drive an impedance at 1k?
BOSOZ and XSOZ
In my review of my new X_SOZ from a earleier post:
"The bas is more tight, grainy and dynamic and still deep."
I felt a littel hesitation wen i wrote "still deep".
Wen a bass seems more structurated or grainy it looses some softness wich can be interpretated as lack of deepness in the bass, but it isn´t rearley.
But I have a feeling, that it could be deeper without loosing the structure.
I still prefer my test X-SOZ, no doubt, even for the bass alone.
This lack of deepness could be caused by the lower inputimpedance in the X-SOZ, so by increacing the C1 and C2 in BOSOZ from 10 to 47uF it shoud go deeper.
I haven´t tryed it out yet, but i am pretty shure that tis is a problem, but how signifant it is i dont now before i have tried it.
The graph attached is from a simulation on BOSOZ an SOZ in combination.
In my review of my new X_SOZ from a earleier post:
"The bas is more tight, grainy and dynamic and still deep."
I felt a littel hesitation wen i wrote "still deep".
Wen a bass seems more structurated or grainy it looses some softness wich can be interpretated as lack of deepness in the bass, but it isn´t rearley.
But I have a feeling, that it could be deeper without loosing the structure.
I still prefer my test X-SOZ, no doubt, even for the bass alone.
This lack of deepness could be caused by the lower inputimpedance in the X-SOZ, so by increacing the C1 and C2 in BOSOZ from 10 to 47uF it shoud go deeper.
I haven´t tryed it out yet, but i am pretty shure that tis is a problem, but how signifant it is i dont now before i have tried it.
The graph attached is from a simulation on BOSOZ an SOZ in combination.
