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In Reply to: RE: There's more than one way to do that... posted by A.Wayne on September 18, 2015 at 13:09:05
Our MA-1 power supply can produce about 50Amps using the same measure that many solid state amplifier manufacturers use.
The issue here is finesse. If you want to create realism, the last thing you want to do is burden the amp in such a way that it makes more distortion because when it does so, its the kind that is audible.
I think you said it yourself- you have enough power so that there is plenty of power for realism. But you might consider what it is that causes realism in the first place. One thing certainly is a lack of distortion (and by this I am making it clear that I don't like presentations that exhibit a large amount of the 2nd order; while they certainly sound sweet, its hard to regard such as neutral).
But in addition to that power, the distortion components that the ear finds as the most audible (IM, and the higher ordered harmonics) will have to be kept to a minimum. That's hard to do when you have a lower impedance. In a solid state amplifier, the output devices have a non-linear capacitive aspect built into the junctions. This capacitance is magnified by current (BTW, the FM radio in your car is tuned by a device called a varactor diode that takes advantage of this principle). If you want to avoid the non-linear capacitive effects on the circuit, its to your advantage to keep the load impedance higher.
Now you can see this sensitivity to load in the specs of any amplifier, even class D.
Another reason 4 ohms is a hard way to go is the speaker cables. Now I am old enough to remember how I was able to go to Ace hardware and get zip cable, and it worked. But back in those days a lot of speakers were higher impedance. If you have a 4 ohm load the cable is just going to be a lot more critical plain and simple. As such it will induce a coloration, so you inherently have to keep it short. This again is easy to demonstrate. RCA published a nomograph showing just how important the speaker cables were back in the 1960s. Essentially, the lower the speaker load impedance, the more the cable works to reduce the damping factor. At 16 ohms its almost a non-issue.
Follow Ups:
try it! you know you want to!
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"But in addition to that power, the distortion components that the ear finds as the most audible (IM, and the higher ordered harmonics) will have to be kept to a minimum. That's hard to do when you have a lower impedance. In a solid state amplifier, the output devices have a non-linear capacitive aspect built into the junctions. This capacitance is magnified by current (BTW, the FM radio in your car is tuned by a device called a varactor diode that takes advantage of this principle). If you want to avoid the non-linear capacitive effects on the circuit, its to your advantage to keep the load impedance higher.
Now you can see this sensitivity to load in the specs of any amplifier, even class D."
So I showed you an example of a class d amp that is not sensitive to load.
Similarly, the IM it produces is below audibility.
Some call this "sterile". I call it accurate.
try it! you know you want to!
The sensitivity to load is just as you quoted me above- the lower the load impedance, the higher the distortion, even in class D amps.
Maybe you should check the specs of the ncore because in some regions, lower impedance loads actually produce less distortion....
try it! you know you want to!
Holy smokes I was just joking about you having 85db speakers, as it turns out they are ~83 db? Wow, I didn't know they made them that inefficient.
Looks like you are stuck with the pucks for the time being, no soup for you!
It says you have a 6-pack of pucks? Is that for surround or are you multi-amping those gluttons?
△ᴉʇɐuᴉɯnllI oᴉpn∀△
RalphI think that most of SS/BJT based amplifiers benefits from 16-ohm load(speaker) vs 4-ohm LS primary from reduced beta drop effect ,
MOS-FET-s ,laterals ,verticals and other FET types don`t suffer from this negative effect , but from high input capacitance which is again highly non linear , and this can be `cured` only with higher standing bias current( A class ) .
Further general problem of SS devices is that N and P complementary power devices is not so complementary as is advertised ,
for example power MOS-FET N & P input capacitances , it is so different , same effect is valid for BJT N & P power devices ,
transfer characteristic is different and not so complementary,
to avoid this N vs P type basic differences some SS amps designers use only same type of power devices , usually only N type connected in SEPP power bridge configuration ,and rarely connected in Circlotron PP power bridge ,
for example somewhere above mentioned Einstein hybrid power amp use Circlotron PP (a)/B class configuration ,
except of this couple examples exist so many others real basic problems related to implementation of SS devices for good audio power amps .
__
"Art which does not have the appearance of art is true art."
- Old Roman saying -
Edits: 09/18/15
In a solid state amplifier, the output devices have a non-linear capacitive aspect built into the junctions. This capacitance is magnified by current
- Ralph
You talking BJT and or MOSFETS, High bias Mosfets dont have this issue , just crank the bias up to reduce. Seriously Ralph, junction capacitance is easily controlled. Tube amplifiers also suffer from parasitic capacitance like anything else.As to speaker wires, we have progressed beyond zip cable at Lafayette, RLC circuits (speaker wires) are available to care of any situation, speakers wires should be short anyway, .5M is about the best , 1M is the max regardless if 8/4/2 ohms , not to mention most good SS amps have pretty low output impedances ....
Regards
Edits: 09/18/15 09/18/15
I guess I'm not understanding why you would want more coloration out of the amp (and distortion of any kind is interpreted by the ear as a coloration....).
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