Folks,
want to build a power amp driver stage with 6BQ5 trioded tube but I wonder what operating point to choose for good sound to drive 6550 tubes.
Could not afford 20mA on a 9K load as this many voltages are not available.
Maybe some good "starved operation" modes are guessed for good sound.
Many thanks in advance.
want to build a power amp driver stage with 6BQ5 trioded tube but I wonder what operating point to choose for good sound to drive 6550 tubes.
Could not afford 20mA on a 9K load as this many voltages are not available.
Maybe some good "starved operation" modes are guessed for good sound.
Many thanks in advance.
KT-88/6550
tested both on Micheals SE with Visaton VIB 200 GF
KT88SE High End Röhrenverstärker
my very first experience in Tube Amplifier.
here another one:
KT88-PSE-Amp, von Christoph Lassok
on Christophs page is an SE with 6SL7.
tested both on Micheals SE with Visaton VIB 200 GF
KT88SE High End Röhrenverstärker
my very first experience in Tube Amplifier.
here another one:
KT88-PSE-Amp, von Christoph Lassok
on Christophs page is an SE with 6SL7.
Hello and many thanks for those replies and informations provided.
The amp should be 6550 SET design, but I suspect that any operating point for 6BQ5 driver would result in too much gain. I first thought to compensate for the gain with a current neg. feedback loop but has come to the conclusion that a 6AQ5 based trioded cathode follower would do the job of driving the load more efficiently, although my first intention was to avoid CF in my design.
The amp should be 6550 SET design, but I suspect that any operating point for 6BQ5 driver would result in too much gain. I first thought to compensate for the gain with a current neg. feedback loop but has come to the conclusion that a 6AQ5 based trioded cathode follower would do the job of driving the load more efficiently, although my first intention was to avoid CF in my design.
Why are you avoiding cathode followers? They don't add much complexity, and will be so low in distortion that they will have absolutely zero impact on audible sound quality.
If you want to go for something a bit easier, you could use a Mosfet as a source follower, this will allow you to drive the 6550 with any triode you want, without fear of loading down your gain stage. run a negative rail about twice the bias voltage (if running fixed bias you will need a negative rail anyway) and have the Mosfet direct coupled to the grids of the output tubes. this will feed the output tubes all the current they want with absolutely zero blocking distortion, and let you run a larger resistor at the input to the output, since it will just be at the grid of the Mosfet. Adjust the output tube bias as you normally would, just at the gate of the Mosfet.
Last edited:
Heres a fine link to the schematic to use
http://www.geofex.com/Article_Folders/mosfet_folly/mosfetfolly.htm
Bangla, do you agree that the Zetex ZVN0545A Mosfet is a good choice for driving a power tube like 6550 with an EF86 voltage amp or is there some better Mosfet available for this application?
http://www.geofex.com/Article_Folders/mosfet_folly/mosfetfolly.htm
Bangla, do you agree that the Zetex ZVN0545A Mosfet is a good choice for driving a power tube like 6550 with an EF86 voltage amp or is there some better Mosfet available for this application?
I like IRF820, or something similar, but there are a ton that people successfully use.
Oh, that question is a bit over my head- limited knowledge, only basics and low equipment too.
For the little zetex, only some thought's- how many mA? voltage? dissipation mW?
Next: current/voltage/gain- frequency linearity?
That all to keep in view necessary?
Because my limitation i try to learn and use for now given schematics.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.