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Old 15th March 2013, 12:47 PM   #8651
jcx is online now jcx  United States
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essentially content free as far as amplifier's effect on "sound"

Quote:
Bob Stuart was saying this in the 1970's " Causes of distortion in audio amplifiers due to loss of information " i.e the soul .

TAS 194: Meridian Audio's Bob Stuart Talks with Robert Harley | The Absolute Sound
only have to appeal to psychoacoustics to "explain" why bad measuring amplifiers may be sometimes be tolerable to listen to

the "hearing below the noise floor" is typical audiophile BS - ignores frequency dependence, critcal band theory - I haven't seen any psychoacoustic test showing the purported "below the noise floor" resolution when a fully informed description of signals, noise and our hearing limits have pulled together in one test

Last edited by jcx; 15th March 2013 at 12:58 PM.
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Old 15th March 2013, 12:50 PM   #8652
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I have a Park amplifier by Marshall . It uses TDA 2030 from memory . It sounds very like a Marshall .

The met Mr Grinrod who designed some of Marshalls best ( He was meeting Mr Kondo , if not too secret I hope , Kondo and Jim Marshall " nearly " worked together , a very long story ) . his best was when his wife was in hospital . He did it so as to distract himself from the reality of something he personally could not fix .

I repaired a Rotel RA 931 . Like a fool it was sent on it's way before finding out what the thin copper strips inside do ? The are not emitter resistors as those were 0R22 . It's bugging me now . Lovely amp . So simple and so nice . Different than when in 1995 I saw them almost every week . The bias was 2mV @ R22 . I reset it to the default value of original Rotel's 4.3mV@ R22 . I noticed that the bias peaked after 10 minutes and settle to 3.3 mV hours later ( from 4.3 ) . Did someone at Rotel UK read Douglas Self on doubling ? To me it's not correct if not to Stan Curtis original .

36 V rails ( I get 242 V typical ) . NE5532 phono , OPA2604 inter stage . Amp , generic op amp style with minimum parts . Superb layout ( puts me to shame ) . I did a bit of Dvv on it and gave some capacitors new homes . Toroid looks about 200 VA . DC offset identical 75 mV . That looks suspiciously like a choice to me ?

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Old 15th March 2013, 01:01 PM   #8653
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Originally Posted by jcx View Post
essentially content free as far as amplifier's effect on "sound"



only have to appeal to psychoacoustics to "explain" why bad measuring amplifiers may be sometimes be tolerable to listen to

the "below the noise floor" is typical audiophile BS - ignores frequency dependence, critical band theory - I haven't seen any psychoacoustic test showing the purported "below the noise floor" resolution when a fully informed description of signals, noise and our hearing limits have pulled together in one test
I always thought Bob totally sincere . Also he could tolerate Micheal Gerzon ( not known to ever have a bath ) . That allowed Bob to have all of Micheal's patents . Most people treated Michael as completely mad . It would never happen when in print because this transformed Michael . How I wish I had treated him better . Are all youngsters mildly psychopathic ? I was very caring for a youngster , the previous statement still applies . Worst of it is , it would be self interest now if had been more of a friend . For all that Michael was intellectuality a colossus and it was very intimidating . DF 96 on steroids .
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Old 15th March 2013, 01:18 PM   #8654
jcx is online now jcx  United States
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I was surprised by the line - possibly a "throw-away", trying keep up enough FUD for Meridian's marketing case

most of the article dealt with digital audio CD reproduction limits - I am not doctrinaire that RedBook is "prefect" - I regularly link his resolution article, dither discussions

but the case for 44.1 pre-ringing audibility, requirement for higher sample rates still isn't convincing enough for the psychoacoustic textbooks
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Old 15th March 2013, 03:12 PM   #8655
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The thing that sticks in my mind is how good the 14 Bit Meridian players sounded . Detail they shouldn't have was abundant ( and so nice / accurate ) . I wish I kept the one that was traded in cheaply as I was astonished how good it was . Forgive my typo's ( previously and often ) . The last was taking my ex to the bus station and I was late . I always compare myself with Frasier , she definitely is Lilith .

I dislike CD , so to like one is rare .
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Old 15th March 2013, 05:22 PM   #8656
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Quote:
Originally Posted by nigel pearson View Post
The thing that sticks in my mind is how good the 14 Bit Meridian players sounded . Detail they shouldn't have was abundant ( and so nice / accurate ) . I wish I kept the one that was traded in cheaply as I was astonished how good it was . Forgive my typo's ( previously and often ) . The last was taking my ex to the bus station and I was late . I always compare myself with Frasier , she definitely is Lilith .

I dislike CD , so to like one is rare .
What about an LP12 ...?
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Old 15th March 2013, 05:34 PM   #8657
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Questions for suggestions Gents ...

I want to upgrade the PSU caps in a PS-Audio amp i'm currently using, it currently using 12,000ufx4 in the psu, my options are ,

Leave whats there currently and add an addition external cap bank of 4 x68,000uf..

or

Remove current caps and install the 68K in it's place on the copper rails and remote the transformer to a separate chassis ...


Thoughts ...?
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Old 15th March 2013, 05:38 PM   #8658
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Originally Posted by a.wayne View Post
What about an LP12 ...?
Like having it on with Mrs Parkinson.
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Old 15th March 2013, 05:50 PM   #8659
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Quote:
Originally Posted by a.wayne View Post
Remove current caps and install the 68K in it's place on the copper rails and remote the transformer to a separate chassis ...


Thoughts ...?
Remove trafo and replace with external SMPSU, use space previously occupied by trafo to install a multitude of paralleled lytics and series inductors to filter out switching hash. Be sure to install decent (segmented) additional CMchoke on mains side of SMPSU.
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Old 15th March 2013, 05:52 PM   #8660
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@ Dutchie......... Depends on what she looks like ........
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