Mainly because the amp has low OLG but wide OL bandwith due to
use of low gain/degenerated stages , thus the amp has good OL linearity
but the feedback ratio is low and constant with frequency , hence the distorsion
being constant with frequency.
Increasing the OLG and reducing the OL bandwith of this amp would
of course reduce THD at low frequencies but it would stay the same at 10KHZ
as in the low OLG variant once the loop is closed.
use of low gain/degenerated stages , thus the amp has good OL linearity
but the feedback ratio is low and constant with frequency , hence the distorsion
being constant with frequency.
Increasing the OLG and reducing the OL bandwith of this amp would
of course reduce THD at low frequencies but it would stay the same at 10KHZ
as in the low OLG variant once the loop is closed.
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Again, it depends on topology of SS amps. And of tube amps, of course.
The best results I still got combining SS and tubes. Can't get such results using SS only, or tubes only.
Agree that a lot of ill designed SS topologies have perfs that can be
reached with tube designs but a minimaly thought SS design can not
be approached by a tube topology unless you re using a 800/1000V
slope such that you amp work only in one or two % of the curve ,
wich amount to design a MC3500 to reach perfs at a few watts that
are easily obtained by 20W SS amps......
reached with tube designs but a minimaly thought SS design can not
be approached by a tube topology unless you re using a 800/1000V
slope such that you amp work only in one or two % of the curve ,
wich amount to design a MC3500 to reach perfs at a few watts that
are easily obtained by 20W SS amps......
No.
You can use as deep feedback loops in tube design as in SS design, despite tubes are more linear than transistors. I still don't see why you always compare deep feedback transistor designs with no feedback tube designs. Didn't you experiment with them?
Try common emitter transistor stages with no feedback at all, then let's talk.
Saying no is somewhat short as an argument if it s not backed by numbers
wich invariably say the same old story for a few decades.
So far , all the tests and reviews that i have knowledge of clearly show
tubes gears as being technicaly inferior to silicon made items.
Indeed , the norm of what is good enough and what is not is not
decided by the amps designers but by the source requirements.
At the times of the LPs with about 70/75dB S/N ratio , amps with
THD at -80dB , hence below noise levels , were good enough.
Currently , with CD and its theorical 96dB S/N ratio being the reference source ,
amps must target THD at -100db , that is , an order of magnitude better
than 30 years ago.
wich invariably say the same old story for a few decades.
So far , all the tests and reviews that i have knowledge of clearly show
tubes gears as being technicaly inferior to silicon made items.
Indeed , the norm of what is good enough and what is not is not
decided by the amps designers but by the source requirements.
At the times of the LPs with about 70/75dB S/N ratio , amps with
THD at -80dB , hence below noise levels , were good enough.
Currently , with CD and its theorical 96dB S/N ratio being the reference source ,
amps must target THD at -100db , that is , an order of magnitude better
than 30 years ago.
No John for the plinus amp I had posted the graphs of before and JA commented on .....
Lol ..... High level global sarcasm .......
PLook back I had asked this very question , what 1000 post ago , why no more hybrids , JC. Why no hybrid halo's ....
Why no hybrids? LAMM sells hybrids now, even Samsung does. No hybrids?
http://www.theverge.com/2012/1/3/26...-theater-systems-announced-vacuum-tube-hybrid
Amplifier theory question. Beginner, so please be patient. Again, looking at my test mule, the DH-120. If I am willing to sacrifice swing in the VAS by regulating the input/VAS rails about+/- 40 V, which should be sufficiently below the 52 unloaded each, I don't see how that would really change the output into realistic loads. What would I be losing, and what, if anything would I be gaining? This is a 60W "rated" amp and the rails are fused at 4A. I should not need more that 60V total swing driving the outputs. 50% seems like a suitable derating of the outputs.
I had also considered putting a choke in line with rail isolation resistors and increase the storage on the VAS side. Not as good as regulation, but immune from dropout if the rail sagged more than it should.
My new outputs did not come today so I still have time to ponder. I'll be able to leave you alone a bit when I have something to play with.
I had also considered putting a choke in line with rail isolation resistors and increase the storage on the VAS side. Not as good as regulation, but immune from dropout if the rail sagged more than it should.
My new outputs did not come today so I still have time to ponder. I'll be able to leave you alone a bit when I have something to play with.
A bit harder to get quality with the transistors available. The 2N2222A's ( On Semi from China) had hFE of 21, minimum is 100. The 2n5550's were around 115. Half "typical" and the 2N5401 were about 90, again less than half "typical". The Motorolas coming out, with the exception of the few that were damaged, were above half typical.
Gonna have a serious talk with Digi-Key.
Gonna have a serious talk with Digi-Key.
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