i just checked the topology schematic on that preamp...it is a bride of son of zen with tubes......
is it under licens or?...
/micke
is it under licens or?...
/micke
The BOSOZ isn't patented. It's just a nicely executed solid state differential. As such, anyone is free to build one with any sort of gain devices that come to hand.
In the meantime, have a look at some of their other schematics and see if you find anything else that looks familiar...
Grey
In the meantime, have a look at some of their other schematics and see if you find anything else that looks familiar...
Grey
Not only is the BSOZ not patented, it's design would
be considered a trivial example of prior art by the
patent office, as would the other Zen circuits published
to date. Almost as trivial as the stupid net business
models clogging the patent office at this time.
Victor at BAT is what we used to refer to as a gentleman
and a scholar, and if by chance he was inspired by
BSOZ, then I would be flattered.
be considered a trivial example of prior art by the
patent office, as would the other Zen circuits published
to date. Almost as trivial as the stupid net business
models clogging the patent office at this time.
Victor at BAT is what we used to refer to as a gentleman
and a scholar, and if by chance he was inspired by
BSOZ, then I would be flattered.
BAT preamps
Hello,
i´m in service for BAT since 1997 (not authorized)
and know Victor´s preamps in deatail. he always uses simple Diffamps working on current sources.
The differences are in the Tubes (6922 & 6H30P-DR)
and Fets and the current flowing.
Therefore he called his preamp philosophy "Unistage"
Reinhard
Hello,
i´m in service for BAT since 1997 (not authorized)
and know Victor´s preamps in deatail. he always uses simple Diffamps working on current sources.
The differences are in the Tubes (6922 & 6H30P-DR)
and Fets and the current flowing.
Therefore he called his preamp philosophy "Unistage"
Reinhard
Hello,
for schematics ask Victor Khomenko at www.balanced.com.
I would not feel comfortable to give you in house documents.
But where is the problem: Take the BOSOZ and scale it up for tubes. With + - 150 V rails and some 6922 you will get good results.
For further questions do not hesistate to contact me at: in.audio@t-online.de
Reinhard
for schematics ask Victor Khomenko at www.balanced.com.
I would not feel comfortable to give you in house documents.
But where is the problem: Take the BOSOZ and scale it up for tubes. With + - 150 V rails and some 6922 you will get good results.
For further questions do not hesistate to contact me at: in.audio@t-online.de
Reinhard
Interesting; I've often wondered what comprised the fundamental basis for the BAT "Unistage" design. The benchmark results always indicated something a bit more sophisticated than just a high-performance SET (as in the conrad-johnson ART "composite triode" configuration). Does the BAT Unistage use solid-state or vacuum-tube current-sources for the differential pair? Also, does the BAT Unistage use cascode elements on the differential pair and/or the current-sources?
Hello,
the unistage is always a differential amplifier with resistiv anode loads.
For the cathode current sources you find solid state and vacuum tube, depending on model.
have a look at their website, it is very informative.
Reinhard
the unistage is always a differential amplifier with resistiv anode loads.
For the cathode current sources you find solid state and vacuum tube, depending on model.
have a look at their website, it is very informative.
Reinhard
The BAT Web site only offers ambiguous hints at the specifics of the underlying topology, so I greatly appreciate your willingness to directly state the fundamental topology of the BAT Unistage (differential pair, high-level bias via current-source, capacitor-coupled output, no global-loop feedback). Combining this core design information with hints provided on the BAT Web site and information gleaned from BAT product reviews, a bit of insight into the BAT designs becomes are bit more apparent.
The Stereophile review of the BAT VK55SE (Stereophile: Balanced Audio Technology VK-55SE power amplifier) indicates that the baseline (non-SE) model uses resistive current sources while the upgraded SE model is configured with vacuum-tube–based (6922) current sources. The BAT Web site does note that the REX pre-amplifier allows the owner to select from one of three options for the differential-pair current-source (based on either a 6C19, a 6H30 or a 5881 vacuum-tube) in order to "tune/tailor" the sound of the REX pre-amplifier. According to a comment from BAT to Stereophile, "BAT claims, [the vacuum-tube current-source] provides "a more soulful portrayal of musical texture and instrumental timbre."
So a BAT Unistage is a single-stage design, comprised of a differential pair (based on a range of vacuum-tube models (including the BAT in-house "SuperTube")), powered by current-sources (again, using various vacuum-tube models and/or resistive-sources), driving resistive plate loads, capacitively-coupled to the output (via the BAT custom in-house paper-in-oil capacitors) with no intervening buffers (or global-loop feedback). The specific components/vacuum-tubes are selected to voice the BAT Unistage for a specific sonic character in a given application.
As a student of the art of audio-engineering, this is great information. Thanks!
The Stereophile review of the BAT VK55SE (Stereophile: Balanced Audio Technology VK-55SE power amplifier) indicates that the baseline (non-SE) model uses resistive current sources while the upgraded SE model is configured with vacuum-tube–based (6922) current sources. The BAT Web site does note that the REX pre-amplifier allows the owner to select from one of three options for the differential-pair current-source (based on either a 6C19, a 6H30 or a 5881 vacuum-tube) in order to "tune/tailor" the sound of the REX pre-amplifier. According to a comment from BAT to Stereophile, "BAT claims, [the vacuum-tube current-source] provides "a more soulful portrayal of musical texture and instrumental timbre."
So a BAT Unistage is a single-stage design, comprised of a differential pair (based on a range of vacuum-tube models (including the BAT in-house "SuperTube")), powered by current-sources (again, using various vacuum-tube models and/or resistive-sources), driving resistive plate loads, capacitively-coupled to the output (via the BAT custom in-house paper-in-oil capacitors) with no intervening buffers (or global-loop feedback). The specific components/vacuum-tubes are selected to voice the BAT Unistage for a specific sonic character in a given application.
As a student of the art of audio-engineering, this is great information. Thanks!
Again, there are models (VK30) with solid state current sources. The current source is a so called ring of two composed by a MosFet and a BJT working on a supply of minus 15 Volts.
Reinhard
Reinhard
borbely balanced line stage pre amp
Erno Borbely wrote an article in glass Audio back in the 90's about a balanced tube line stage pre amp which I built many years ago and sounds great. You can review it on his web site Home Page. It is basically close to the mosfet version but uses mu followers following the balanced tube input.
It seems like the Bat design.
Erno Borbely wrote an article in glass Audio back in the 90's about a balanced tube line stage pre amp which I built many years ago and sounds great. You can review it on his web site Home Page. It is basically close to the mosfet version but uses mu followers following the balanced tube input.
It seems like the Bat design.
No, Borbely´s design is a low powerd differential and buffers.
BAT´s design is a high power/current differential and NO buffer. The plate load resistors are between 2K and 500 ohms depending on model, tube and tube quantity.
Reinhard
BAT´s design is a high power/current differential and NO buffer. The plate load resistors are between 2K and 500 ohms depending on model, tube and tube quantity.
Reinhard
Reinhard,
Let's see if we can clarify the situation; is the attached simplified schematic close to representing a BAT UniStage configuration?
* The input/output connections are always balanced XLR connectors.
* The differential-pair is typically based on a 6H30 dual-triode in the BAT UniStage, configured for a high level
* The differential-pair plate resistor values range between 500-2000 ohms
* The output coupling-capacitors are usually BAT custom oil capacitors.
* The differential-pair is typically based on a 6H30 dual-triode in the BAT UniStage, configured for a high level
of Class-A bias current to enable a low output impedance.
* The current-source could be based on either solid-state or vacuum-tube elements. * The differential-pair plate resistor values range between 500-2000 ohms
* The output coupling-capacitors are usually BAT custom oil capacitors.
Sometimes, a picture makes is easier for everyone to visualize the circuit topology... 😀
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Excellent! And very interesting; so the 6H30's are paralleled for increased transconductance and lowered noise (ideally, about 3dB lower noise for each doubling of the tube count)? Hmmm, so about 25mA of standing bias current per triode section? Ah, then a single tube would have 2K plate resistors, a pair of tubes would have 1K plate resistors and a quad of tubes would use 500R plate resistors, right?
There is some excellent information on I-series shunt volume control and VK 60 autobias on their homepage, look for recources/white papers,
Reinhard
Reinhard
The volume control hasn't been forgotten; however, the BAT UniStage is employed throughout the product line, not just in pre-amplifiers, so the BAT attenuator is logically a separate point for discussion. The core UniStage circuit topology is the focal point of the thread.
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