Hello,
I liked very much the article for the high efficiency drivers and current source amplifiers.May I ask a couple of questions .....?
-Is the F1 amplifier single or double rail PS?
-I know that a source follower is generally not considered a gain stage and the F1 is a one stage amplifier; what is its gain?
-what power may I expect - in terms of numbers - from a zen source follower biased at 2 amps and driven directly by the output of a standard cd player(in single ended mode , non balanced)?
-the F1 is balanced single ended amplifier;the biasing network in parallel with the amp and speaker is referred to ground. Does it change anything in balance mode, from a response point of view?
****************************************************
I am enjoing the Jordans with a zen current source single rail + the bias network ; I like the combination a lot and looking for the possibility of a nice balanced source follower I have to decide if some additional voltage gain is needed... ... it all depends on how loud I want they to play
I liked very much the article for the high efficiency drivers and current source amplifiers.May I ask a couple of questions .....?
-Is the F1 amplifier single or double rail PS?
-I know that a source follower is generally not considered a gain stage and the F1 is a one stage amplifier; what is its gain?
-what power may I expect - in terms of numbers - from a zen source follower biased at 2 amps and driven directly by the output of a standard cd player(in single ended mode , non balanced)?
-the F1 is balanced single ended amplifier;the biasing network in parallel with the amp and speaker is referred to ground. Does it change anything in balance mode, from a response point of view?
****************************************************
I am enjoing the Jordans with a zen current source single rail + the bias network ; I like the combination a lot and looking for the possibility of a nice balanced source follower I have to decide if some additional voltage gain is needed... ... it all depends on how loud I want they to play
Briefly:
Single rail.
I consider a source follower to be a gain stage.
13.8 dB into 8 ohms.
The output is balanced at 13.8 volts DC, and the
speaker is attached to those two output terminals,
and not to ground.
An ordinary CD player puts out a couple of volts, so let's
say 2 volts, which is 1/2 watt into 8 ohms. 1 watt peak,
with about .3 amp peak. You won't need the 2 amp bias
in this case.
Single rail.
I consider a source follower to be a gain stage.
13.8 dB into 8 ohms.
The output is balanced at 13.8 volts DC, and the
speaker is attached to those two output terminals,
and not to ground.
An ordinary CD player puts out a couple of volts, so let's
say 2 volts, which is 1/2 watt into 8 ohms. 1 watt peak,
with about .3 amp peak. You won't need the 2 amp bias
in this case.
Transconductance is a nifty term for comparing apples and oranges.
What you're doing is taking a voltage input and converting it to a current output. Since the terms (voltage and current) are different, you can't use a simple ratio like Volts/Volts or Amps/Amps. So they invented a term that meant voltage-in/current-out.
Whether something is called a "voltage amp" or a "current amp" is kinda vague...there's no clear dividing line between them; it's a sliding scale. You can look at it in terms of the output impedance of the circuit if you want. A circuit with a low (ideally zero) output impedance is a voltage amp. One with a high output impedance (ideally infinite) is a current amplifier. Between those two extremes you have to split hairs.
Most amps have a real low Zout. This translates into a high damping factor and looks good on a spec sheet. It's also good for controlling wayward woofers. Nelson's F1 has a comparatively high Zout (though nowhere near infinite). This kind of circuit is good for dealing with heat-induced increases in the impedance of a speaker's voice coil, for instance.
Out of time. More later.
Grey
What you're doing is taking a voltage input and converting it to a current output. Since the terms (voltage and current) are different, you can't use a simple ratio like Volts/Volts or Amps/Amps. So they invented a term that meant voltage-in/current-out.
Whether something is called a "voltage amp" or a "current amp" is kinda vague...there's no clear dividing line between them; it's a sliding scale. You can look at it in terms of the output impedance of the circuit if you want. A circuit with a low (ideally zero) output impedance is a voltage amp. One with a high output impedance (ideally infinite) is a current amplifier. Between those two extremes you have to split hairs.
Most amps have a real low Zout. This translates into a high damping factor and looks good on a spec sheet. It's also good for controlling wayward woofers. Nelson's F1 has a comparatively high Zout (though nowhere near infinite). This kind of circuit is good for dealing with heat-induced increases in the impedance of a speaker's voice coil, for instance.
Out of time. More later.
Grey
A transconductance amplifier is a fancy name for current
source. The input voltage is translated into a specific
output current, not a voltage like with regular amplifiers.
source. The input voltage is translated into a specific
output current, not a voltage like with regular amplifiers.
till said:
Yes. SOZ has a 16 ohms output impedance as given, and
you can set it to any reasonable value.
Thanks. So we don´t need to buy a F1 😉
I think about SOZ-lite with bulbs instead of 8 Ohm resitors.
Do i read it right, the favorite of all was DX55 in Kleinhorn? Would this also be the best driver in a J-Low style enclosure, maybe not 25 but 36 inch with ? Will there be plans for the kleinhorn?
I think about SOZ-lite with bulbs instead of 8 Ohm resitors.
Do i read it right, the favorite of all was DX55 in Kleinhorn? Would this also be the best driver in a J-Low style enclosure, maybe not 25 but 36 inch with ? Will there be plans for the kleinhorn?
How 'bout a current feedback pair*? If you're like me -- and I know I am -- I already have a BOSOZ which ought to drive the low input impedance of a current feedback pair just fine.
I don't really have a loudspeaker cut out for current drive, though, so I'm not liable to try it any time soon.
eL
---
* If you have an EE text around, and if the term 'current feedback pair' is unfamiliar, look up "shunt-series feedback". It takes an input current and delivers a higher output current.
I don't really have a loudspeaker cut out for current drive, though, so I'm not liable to try it any time soon.
eL
---
* If you have an EE text around, and if the term 'current feedback pair' is unfamiliar, look up "shunt-series feedback". It takes an input current and delivers a higher output current.
F1
Hello NP,
will there be a white paper of the F1 or more info available for the DIY´ers.
Reinhard
Hello NP,
will there be a white paper of the F1 or more info available for the DIY´ers.
Reinhard
I'm not planning on publishing the schematic until after the
100 are sold, but you can see the simplified version when
it goes up on the site as the owner's manual. In the meantime,
just think if it as a SOZ with constant current sources.
100 are sold, but you can see the simplified version when
it goes up on the site as the owner's manual. In the meantime,
just think if it as a SOZ with constant current sources.
That's interesting .
Today I went up with the Aleph s current sources and in balanced mode . The results are incredibly promising with the Jordans . I am not using the horn yet , but in a Diapason Micra cherry wood enclosure( click to see the Micra 2 enclosure ). They are pretty happy togheter for my taste. Btw I am trying to figure out what it would be the way to accept both bal and se signals in the amp as it is now : two indipendent current sources that shares the PS only.
Today I went up with the Aleph s current sources and in balanced mode . The results are incredibly promising with the Jordans . I am not using the horn yet , but in a Diapason Micra cherry wood enclosure( click to see the Micra 2 enclosure ). They are pretty happy togheter for my taste. Btw I am trying to figure out what it would be the way to accept both bal and se signals in the amp as it is now : two indipendent current sources that shares the PS only.
Obviously besides input noise rejection, the only difference
I experience between balanced and single-ended input on
the circuit is more distortion at high frequencies, but the
harmonics which occur are largely ultrasonic, so it hasn't shown
up as a subjective issue.
I experience between balanced and single-ended input on
the circuit is more distortion at high frequencies, but the
harmonics which occur are largely ultrasonic, so it hasn't shown
up as a subjective issue.
Mr. Pass
How does F1 compare soniclly to Aleph 2 or Zen amplifiers when they are compared on Fostex or Lowther drivers in this huge back loaded horn from the article?
Bartek
How does F1 compare soniclly to Aleph 2 or Zen amplifiers when they are compared on Fostex or Lowther drivers in this huge back loaded horn from the article?
Bartek
zygibajt said:
I haven't put Fostex drivers into the Kleinhorns yet, but I
have driven the Lowthers with Aleph 30's in comparison. The
result is so different in terms of loading and/or eq for the two
cases that a comparison is not very valid, but you can make
both of them sound excellent.
At this time, the system is the DX55 driven by an F1 loaded with
22 ohms and I use an equalizer to flatten out the response,
most particularly to reduce the output of the horn about 8 dB
for an octave centered about 80 Hz.
It sounds good enough for last night's 5 hour listening session.
😎
The sketch shown in the owner`s manual of the first watt amplifier reminds me of the Aleph P preamlifier schematic which is a transconductance type too.
The Aleph P is equipped with two current sinks instead of one used in the first watt amp. This seems to be due to the fact that first watt is a power amp and the variable resistor in the preamp which allows adjusting the gain would get far too hot in a power amp application.
After all a very interesting approach!
My plan regarding current driven loudspeakers is to build up an open baffle subwoofer with current driven chassis (starting this fall/winter season). I hope to reduce distortion with that measure. I`ll post when I`ll have some results.
regards, pozo1992
The Aleph P is equipped with two current sinks instead of one used in the first watt amp. This seems to be due to the fact that first watt is a power amp and the variable resistor in the preamp which allows adjusting the gain would get far too hot in a power amp application.
After all a very interesting approach!
My plan regarding current driven loudspeakers is to build up an open baffle subwoofer with current driven chassis (starting this fall/winter season). I hope to reduce distortion with that measure. I`ll post when I`ll have some results.
regards, pozo1992
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