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Old 28th November 2012, 11:05 PM   #7691
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Power amps should still be 50V/us for 100W, 100V/us for 400W. See JC-1 power amp for what you get.
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Old 29th November 2012, 08:57 AM   #7692
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Power amps should still be 50V/us for 100W, 100V/us for 400W. See JC-1 power amp for what you get.
John Hello . We went through this some time ago , this was the question I never asked . If one had to rescue an amp for a friend and didn't want to get too involved would input bandwidth limiting be enough ? Beauty of that is the friend with virtually no knowledge could find a solution in his spare time . He would feel he broke into our world just a little . Lets assume this guy loves/understands music so is well equipped to be a human oscilloscope .

I remember about some NZ guy who broke land speed records at Bonneville using a pre WW2 Indian . His slew rate looked wrong ( engine ) . He tweaked his aerodynamics to the point of burning his leg . If you see the film it is far too good to be true ( I wasn't there so can not say , the records speak for themselves I guess ) .
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Old 29th November 2012, 10:34 AM   #7693
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About current output . I am reminded about car batteries . The larger the battery the quicker the engine starts it seems . The cabling to the components being the same . Sure you can observe this and that about the motor and the battery . It still is dramatic when observing it .
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Old 29th November 2012, 11:03 AM   #7694
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You make things more complicated than you need to Nigel. MOST people do not need 50V/uS, only serious audiophiles with wide band sources, such as moving coil cartridges or SACD.
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Old 29th November 2012, 11:32 AM   #7695
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Like everything in life, more is better, most is too much ......
Like hell!

Too much food cuases gout and obesity.

Too much sweets causes diabetes.

Too much spending causes bankruptcy.

Too much sex causes heart attack.
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Old 29th November 2012, 11:38 AM   #7696
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You make things more complicated than you need to Nigel. MOST people do not need 50V/uS, only serious audiophiles with wide band sources, such as moving coil cartridges or SACD.
Thank you for saying that, John, that's exactly what I've been telling Nige. Also, he does it the wrong way around, he simplifies things which should be more complicated for better effect, and makes more complex things which should be kept as simple as possible.

For example, the second stage of voltage amplification is usually the one which does most of the work, and while you can use a simple transistor, it would be much better to use a proper cascode stage, or some such. Yes, it does make matters more complex, but for the same amplification factor its natural distortion will be lower to much lower, reducing the need for so much global NFB.
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Old 29th November 2012, 11:39 AM   #7697
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The latter no DVV . I suspect it creates a lack of appreciation ?
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Old 29th November 2012, 11:44 AM   #7698
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Originally Posted by nigel pearson View Post
About current output . I am reminded about car batteries . The larger the battery the quicker the engine starts it seems . The cabling to the components being the same . Sure you can observe this and that about the motor and the battery . It still is dramatic when observing it .
Not necessarily so, Nige. A smaller but better charged battery may be better yet. Also, it greatly depends on the quality and power of the starter, and here yopu can see a wild variance in what people use. Lastly, the matter of your alternator is not an insignificant one, as it is directly related to how full your battery is at any moment.

Some manufacturers use skimpy little alternators, which take forever to charge the battery, causing it to be really stressed every time you want to switch the engine on if you haven't driven the car for a couple of day.

Personally, I view car batteries in exactly the same way I view capacitors in an audio device. The first chance I get, I kick the supplied battery and throw in a Bosch or Varta silver based battery, using the biggest one I can possibly fit into the given space. I never regretted this small extravagance.
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Old 29th November 2012, 11:48 AM   #7699
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The latter no DVV . I suspect it creates a lack of appreciation ?
Yeah, that too. Remember what Will from Stratford said:

Familiarity breeds contempt.

Also, far too often, it's too repetative. Lack of imagination kills it dead.
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Old 29th November 2012, 11:56 AM   #7700
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You make things more complicated than you need to Nigel. MOST people do not need 50V/uS, only serious audiophiles with wide band sources, such as moving coil cartridges or SACD.
Perhaps . I do think adjusting input bandwidth limiting would transform some amps . It would be a nice bit of entertainment . The tightrope between doing something good and something bad could be explored . No broken amplifiers to fix . Happy friend .


I have many friends who have hi fi that has become almost part of the furniture . Often the introduction of something new casts doubts upon the viability of the system . Usually at this point I switch FM radio on and we sit and listen . It sounds OK . I then proceed to modify the amp to accept the newcomer . How many pieces of hi fi have been chucked out because the matching was poor ? Only then for someone to say I preferred my old system except .... We can engineer like it is a Volvo motorcar , mostly we don't need to . One old Hitachi receiver I did this for was so transformed as to be summer and winter . So many little things the designer could not foresee just pushed the right way . Eventually it was given away to his son , sad as I would have liked to own it . It ran the dreaded Bose 901's .
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