Well, I was reacting to your previous post, where you said, for example:
I'm also after "richer, warmer and almost palpable sound", but slowing down things is not the way to go, IME. Accuracy in the system yields super golden sound from classic 50's recordings, and at the same time can handle ultra sharp, current digital recordings with zero unpleasantness or sloppiness,
...
Just been having a bit of a wander around, was led to looking again at the PGP amp website - sub-ppm distortion at full power -and this is on the listening impressions page, http://www.synaesthesia.ca/listening.html:
Obviously I'm from the latter camp, except that the amp behaving itself is only part of the answer - if it ruthlessly reveals that the source componentry is being affected by interference from mains power rubbish, what do you think the right approach then is?
A little soft foam wedged inside the suspension springs will damp them nicely, without affecting the isolation, like AR, Ariston, etc. did.
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If you really check the graph it's clear it is not the belt or pully. It's staring you in the face!
Hint: check the frequency of the wow.
Jan
The repeating large peaks (0.55Hz) are the 'once per revolution' artifact.
Don’t assume that it is all due to the TT.
Most of it (if not all) is due to record eccentricity. How can you verify this?
If you have one test record only, shift it’s position 90, 180 and 270 degrees in respect to the platter and repeat the test. Most probably you will notice a change in the amplitude of the 0.55Hz peak if there is also platter eccentricity (phase cancellation btn possible platter eccentricity and record eccentricity). If you will not notice a change in the amplitude, it is all due to record eccentricity.
Changing to different test records, amplitude will change (differences in records eccentricity).
We also see a second pattern in Jan’s diagram. It is a slower rotational velocity variation around 0.1Hz which may be due to belt and/or suspension stretching (I doubt the latter) .
The spikes and double peaks seen on the main waveform diagram are of some concern.
How did you produce this diagram Jan?
George
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Frank, the Otala/Lohstroh amp proved that you do not need fast output transitors to have a fast amp. Rated at 25W/8 Ohms, it hit 100 V/uS. Is that fast enough for you?
Work it out. To do that, at that output voltage, it would have to do around 500 kHz at full blast at its -3 dB power bandwidth point. To me, it's not so much getting there, but keeping it unconditionally stable once you get there.
To rephrase the question - how many do you know in that power class which pull the same trick today?
Translating that to the output of a 100W/8 Ohms amp, the voltage slew rate would be better than 170 V/uS.
And if that's still not enough, buy a vintage Sansui or Kenwood, they advertised voltage slew rates from 250 to 350 V/uS.
Again, it's like cars - if you want fun, buy a Ford Focus ST, 250 HP of power and road grip like you wouldn't believe, but if that's not fast enough for you, buy a Ferarri V12 with 700 HP, which goes over 200 mph and does 0-60 mph in around 3 seconds. The thing is, to actually drive like that, you need to find a road good enough to allow that. And that won't be the usual city traffic jam during the rush hour.
You said it yourself - to be great, it needs balance. I for example am much more worried about its settling time, once the voltage slew rate is at 100 V/uS and above.
Work it out. To do that, at that output voltage, it would have to do around 500 kHz at full blast at its -3 dB power bandwidth point. To me, it's not so much getting there, but keeping it unconditionally stable once you get there.
To rephrase the question - how many do you know in that power class which pull the same trick today?
Translating that to the output of a 100W/8 Ohms amp, the voltage slew rate would be better than 170 V/uS.
And if that's still not enough, buy a vintage Sansui or Kenwood, they advertised voltage slew rates from 250 to 350 V/uS.
Again, it's like cars - if you want fun, buy a Ford Focus ST, 250 HP of power and road grip like you wouldn't believe, but if that's not fast enough for you, buy a Ferarri V12 with 700 HP, which goes over 200 mph and does 0-60 mph in around 3 seconds. The thing is, to actually drive like that, you need to find a road good enough to allow that. And that won't be the usual city traffic jam during the rush hour.
You said it yourself - to be great, it needs balance. I for example am much more worried about its settling time, once the voltage slew rate is at 100 V/uS and above.
Always educational to look at what's happening with electronic keyboards designed for home use - the "make an orchestra or band happen" in your lounge room type of thing. The people there are so far ahead of the curve compared to audiophiles, it's almost scary! All digital, unbelievable versatility, every known sound, and 10 times as many that you couldn't believe possible - done with superb clarity and tone, and able to go easily to room filling volumes ...
Where did the reproduction of audio mob go so wrong ... ?
Where did the reproduction of audio mob go so wrong ... ?
are you serious? - or is this article totally wrong http://www.electrocompaniet.com/files/reviews/2012_jan_Hifi-news_Vintage_EC.pdf
Really sharp slew rate is needed for FB to work properly, in amplifiers that essentially depend upon it. For those that have minimal global FB, far less of a problem, but then their outputs working properly are very dependent on the load being 'nice' to them. So, it's not Black and White - I prefer the amp to be able to take on all comers in terms of the load, and have the speed internally fast enough to react to all transient current demands. And that's not even considering how well behaved the power supply is while this is going on ...
Bingo.
Bingo.
Bingo.
Adjust+
Actually the major portion is from the record hole which is larger than the spindle diameter leading to an eccentric record position, and by finicking the LP position I can bring it almost to zero.
Jan
Its a basic Mitchell TechnoDec. I am using a clamp but that doesn't prevent the record being placed eccentric before clamping.
The test record hole is clearly larger than the spindle diameter, but I haven't checked out which of the two is out of tolerance. The test record comes with Adjust+.
Jan
The test record hole is clearly larger than the spindle diameter, but I haven't checked out which of the two is out of tolerance. The test record comes with Adjust+.
Jan
Thank you Jan.
In case you have finely adjusted the azimuth of your cartridge acc to this SW, were you able to notice audible difference compared to your previous ‘0 degrees’ setting?
George
Sorry its an RB-250. Yes its relatively easy to fix it but I just haven't taken the time for it.
Too busy with next Linear Audio Volume
Jan
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