New Info Discussed, Class A, AB, B, and C operation/mode

[steve]

One other point that needs mentioning is the use of UL mode.
UL operation can be used in both A, A2, AB1, AB2, and B. I have
never seen UL used in Class C as distortion is extremely high,
thus not necessary.

Output power of UL operation is similar to Pentode/Tetrode mode,
which is very generally around twice the output power of Triode mode.

Frequency response is different from triode mode (which is also different
than both Pentode/Tetrode mode) as the screen of the tube is connected
to a portion of the output transformer primary, so some negative feedback
etc. As a result, the damping factor is increased a little.

Cheers

steve

Hi Steve,

I have only owned a couple of tube amps and I can only recall for sure that my VAC 90 monos allowed the option to switch to UL. That was so long ago and my system was so simple without using any products to control noise, that I don't recall if I preferred one or the other.

Nick

I think most prefer triode mode over UL. UL does fill in the lower midrange/upper bass
vs triode and controls the highs more, appearing as less. If too much lower
midrange/upper bass, one can use a smaller speaker cable.

I use 11 wires in parallel in each leg, so it is simple for me to remove just one
wire to thin the lower midrange just a little for more like triode mode.

The highs are a different story in that fewer parallel speaker wires will mean a
little higher inductive reactance in the highs, thus reducing the highs.
Of course, with a single, large speaker wire, adjustment is prevented.

cheers

steve

[Nick B]

One other point that needs mentioning is the use of UL mode.
UL operation can be used in both A, A2, AB1, AB2, and B. I have
never seen UL used in Class C as distortion is extremely high,
thus not necessary.

Output power of UL operation is similar to Pentode/Tetrode mode,
which is very generally around twice the output power of Triode mode.

Frequency response is different from triode mode (which is also different
than both Pentode/Tetrode mode) as the screen of the tube is connected
to a portion of the output transformer primary, so some negative feedback
etc. As a result, the damping factor is increased a little.

Cheers

steve

Hi Steve,

I have only owned a couple of tube amps and I can only recall for sure that my VAC 90 monos allowed the option to switch to UL. That was so long ago and my system was so simple without using any products to control noise, that I don't recall if I preferred one or the other.

Nick

I think most prefer triode mode over UL. UL does fill in the lower midrange/upper bass
vs triode and controls the highs more, appearing as less. If too much lower
midrange/upper bass, one can use a smaller speaker cable.

I use 11 wires in parallel in each leg, so it is simple for me to remove just one
wire to thin the lower midrange just a little for more like triode mode.

The highs are a different story in that fewer parallel speaker wires will mean a
little higher inductive reactance in the highs, thus reducing the highs.
Of course, with a single, large speaker wire, adjustment is prevented.

cheers

steve

Hi Steve,

Quite interesting that you use 11 wires in parallel and that you can fine tune the sound by easily disconnecting one or more of the wires.

Nick

[steve]

One other point that needs mentioning is the use of UL mode.
UL operation can be used in both A, A2, AB1, AB2, and B. I have
never seen UL used in Class C as distortion is extremely high,
thus not necessary.

Output power of UL operation is similar to Pentode/Tetrode mode,
which is very generally around twice the output power of Triode mode.

Frequency response is different from triode mode (which is also different
than both Pentode/Tetrode mode) as the screen of the tube is connected
to a portion of the output transformer primary, so some negative feedback
etc. As a result, the damping factor is increased a little.

Cheers

steve

Hi Steve,

I have only owned a couple of tube amps and I can only recall for sure that my VAC 90 monos allowed the option to switch to UL. That was so long ago and my system was so simple without using any products to control noise, that I don't recall if I preferred one or the other.

Nick

I think most prefer triode mode over UL. UL does fill in the lower midrange/upper bass
vs triode and controls the highs more, appearing as less. If too much lower
midrange/upper bass, one can use a smaller speaker cable.

I use 11 wires in parallel in each leg, so it is simple for me to remove just one
wire to thin the lower midrange just a little for more like triode mode.

The highs are a different story in that fewer parallel speaker wires will mean a
little higher inductive reactance in the highs, thus reducing the highs.
Of course, with a single, large speaker wire, adjustment is prevented.

cheers

steve

Hi Steve,

Quite interesting that you use 11 wires in parallel and that you can fine tune the sound by easily disconnecting one or more of the wires.

Nick

Yes. Anyone with multiple parallel speaker wires can test and find out if more
or fewer wires gives optimal reproduction.

The impedance is minimum near lower midrange/upper bass. A change in dc resistance
will affect this band more than higher frequencies on that particular driver. Kinda
changes the slope of the frequency response.

If one uses a 3 way speaker, two crossovers, there could be another range of
frequencies at the 2nd crossover where an impedance dip occurs, where the sound
will also be affected more than other higher frequencies.

I use a two way, so basically at just the one crossover is where the majority
of sonic change occurs.

Cheers

steve

[Nick B]

One other point that needs mentioning is the use of UL mode.
UL operation can be used in both A, A2, AB1, AB2, and B. I have
never seen UL used in Class C as distortion is extremely high,
thus not necessary.

Output power of UL operation is similar to Pentode/Tetrode mode,
which is very generally around twice the output power of Triode mode.

Frequency response is different from triode mode (which is also different
than both Pentode/Tetrode mode) as the screen of the tube is connected
to a portion of the output transformer primary, so some negative feedback
etc. As a result, the damping factor is increased a little.

Cheers

steve

Hi Steve,

I have only owned a couple of tube amps and I can only recall for sure that my VAC 90 monos allowed the option to switch to UL. That was so long ago and my system was so simple without using any products to control noise, that I don't recall if I preferred one or the other.

Nick

I think most prefer triode mode over UL. UL does fill in the lower midrange/upper bass
vs triode and controls the highs more, appearing as less. If too much lower
midrange/upper bass, one can use a smaller speaker cable.

I use 11 wires in parallel in each leg, so it is simple for me to remove just one
wire to thin the lower midrange just a little for more like triode mode.

The highs are a different story in that fewer parallel speaker wires will mean a
little higher inductive reactance in the highs, thus reducing the highs.
Of course, with a single, large speaker wire, adjustment is prevented.

cheers

steve

Hi Steve,

Quite interesting that you use 11 wires in parallel and that you can fine tune the sound by easily disconnecting one or more of the wires.

Nick

Yes. Anyone with multiple parallel speaker wires can test and find out if more
or fewer wires gives optimal reproduction.

The impedance is minimum near lower midrange/upper bass. A change in dc resistance
will affect this band more than higher frequencies on that particular driver. Kinda
changes the slope of the frequency response.

If one uses a 3 way speaker, two crossovers, there could be another range of
frequencies at the 2nd crossover where an impedance dip occurs, where the sound
will also be affected more than other higher frequencies.

I use a two way, so basically at just the one crossover is where the majority
of sonic change occurs.

Cheers

steve

Thanks for that, Steve. Not easy designing quality equipment. I currently have a 2 way, the JMR Voce Rande, and it's probably the best speaker I've ever owned. The only 3 way I ever owned was the Shahinian Diapason. A classic speaker from many years ago. My next speaker might be a 3 way.
Nick