Any benefits, or perhaps better said pro/cons, to all tube amplifier vs hybrid?
What about those designs that use point to point wiring ("hand made") vs. those that use PCBs?
(As you can tell I'm not an electrical engineers.)
Thoughts / comments?
- I should have done some searching - there are a number of webpages that talk about this. Interesting reading. Looks like it comes down to the competence of each design, rather than the approach chosen.
Not only the schematic but more how things are implemented in real life, component choices, wiring (how wiring actually runs) and above all the reference (the ground signal).
Hybrid can supply more output power and does not need transformers to drive low impedances. Tubes behave more linear on higher voltages (they were designed for high voltages) but this is nullified again by transformers which convert the high voltage swing to a low voltage swing again.
Probably the secret to the liquid midrange that we thirst for.
But not too much for the older crowd. They won’t sleep through the night.
Frans has a mod for that. Clip-on hearing bladder aids.
With adjustable moisture control - turn it up to 9 and your vintage tubes will sound as arid as the best worst SS amp - dry, flat and lifeless. A level of boring that only the fully-caffeinated could stay awake for.
Difficult to make a good transformerless output tube amp with a low output impedance. If the OTL amp has an output impedance of 50-60 ohms connected to a set of 300 ohm headphones, not a big deal. Want the output impedance to be lower than the driver impedance, ideally by a factor of 5-10.
Same amp connected to a set of planars with 35 ohm impedance, then it is an issue. The tube amp will struggle to deliver current when the music water has to run uphill to fetch a pail of dynamic crests at the bottom of the bass well. And professionally mixed musical metaphors lose top end bandwidth and drizzle out distorted versions of the mushy lower regions. ;-)
There's also the damping factor. That is the control the amp has on dealing with the back EMF created by the driver. More of an issue with speakers than headphones...usually.
However, some OTL designs have a reasonably low output impedance under 15 ohms. Those wouldn't be too compromised driving efficient 35ohm planars. The design topology and implementation as with everything else is where the details play hopscotch with the devil.
Traditionally, output tubes were isolated from voracious current appetites using a transformer to match the relative impedance mismatch. Really good, linear transformers are expensive tho, so tube amps with high quality trannies usually cost more than OTL amps.