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Old 27th October 2008, 11:25 PM   #11
PALUSE is offline PALUSE  Portugal
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Oh... theres lot of things tha interfer whith our opinion...
1- personal taste.
2- system and room acoustics.
3- Beahave of the unit that we are tweaking.

In my system the same unit with the same tweaking could not give the same results in other person system and room!

Never the less, the opinions are allways necessary and welcome!

Regards


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Old 28th October 2008, 08:24 AM   #12
Mooly is offline Mooly  United Kingdom
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I use OPA2604 (OPA604 single) and find these sonically some of the best. Even the TL072 is better sonically than the NE5532 in many applications. Always try and add a 0.1 mfd directly across pins 4 and 8 soldering very neatly on the IC itself. That is even more important if you are using sockets.
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Old 28th October 2008, 10:46 AM   #13
lineup is offline lineup  Sweden
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Quote:
Originally posted by dw8083
I was playing around with all the "hot" and "hifi approved" opamps in a CD player recently. Tried all the latest and expensive options. Ironically the best sounding opamps for this particular application were ne5534D's. They cost about a $1usd a piece.

You never know.

-David
Some say NE5534 sounds not so good.
Others say NE5534 sound good.

I say, a good opamp will NOT Sound at all.

Only a very bad opamp or very bad use of a good opamp
will cause distortion levels, that are even close
to human hearing thresholds.

This can be an explaination for the different opinions on opamp 'sounds'.
That in fact there is no alteration to the signal that can cause sound.
And so people's minds can have it both ways.
Strictly Subjectively.


In performance NE5534 is way above human hearing.
It has many good parameters for general Audio Use.
And NE5534 is a level better, electrically, than NE5532, which is another opamp. Not a dual NE5534.
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Old 28th October 2008, 06:22 PM   #14
PALUSE is offline PALUSE  Portugal
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Peter Walker from Quad said something like "The best amplifier is a staight wire with gain"!
"But life insn't that simple" said DNM Boss, and i agree, because sound quality have to deal with impedance, which origins phase shift, THD, IMD, noise, which are direct related with the device in which the opamp is insert and the opamp itself!
All the deviations a "device" cause to the original signal are distortion, in which gain is included, but this we forgive gladly!Its the amplifier job!

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Old 28th October 2008, 10:51 PM   #15
lineup is offline lineup  Sweden
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until we can come up with a better overall measurement
we will have to stick with THD
if it was that really bad, then we would have replaced it many years ago

THD does not give the exact level of all forms of distortion
but you can bet,
if THD is low,
then this indicates a good performance and a good circuit
and most other distortions will be at low level

if THD is high, there is a great probability other distortions can be high
and even if not, it is already bad having a high THD
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Old 29th October 2008, 12:29 AM   #16
PALUSE is offline PALUSE  Portugal
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Probably a good way to see the garbage an amplifier produce is a FFT analyser, and then you can see a good bunch of harmonics of all orders to the lowest amplitude, which is noise!

Bye!

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Old 4th November 2008, 02:22 PM   #17
impuls is offline impuls  Yugoslavia
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The best combination for NAD cd players is LM6172 in de-emphasis and OPA2134 in buffer. Better than 2604 and 2134.
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Old 7th November 2008, 08:06 PM   #18
PALUSE is offline PALUSE  Portugal
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The DACs used in the NAD cd players of the serie C54X, are Burr Brown ICs with digital oversampling filter and digital de-emphasis, bitstream dac and voltage output stage. If we want we can cut the opamp cr...p and get a passive lowpass filter if we attack the output stage with a competent impedance to match the maximum current capability of the DAC!In the PCM1732 case, the HDCD version that is instaled in the C541, C541i and C542, the maximum output voltage is 0,57xVcc, which is in the normal situation 0,57x5=2,85Vpp Maximum, with a minimum impedance of 5K Ohms!What do we need more?!
We need to design a competent passive lowpass network, thats all folks!We dont have balanced outputs per dac like in the old Philips SAA7350 or TDA1547, or other BB dacs, unless we use one PCM1732 per channel with one dac output out of phase to create a diferential output and reduce noise floor, or get a balanced output!

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Old 16th November 2008, 02:36 PM   #19
PALUSE is offline PALUSE  Portugal
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Correction to the timeline of Philips CD-850II:
Elnas and OPA2604 - 1996
OPA2134 - 2000
Tray Gear + 3300uF + (50uH Coil 1 Amp) + 1000uf at the +5V power line + 1mH mini coils replaced the 22 Ohms fuse resistors in the +/-15V of the opamps - November 2008
The 3300uF serves all the +5V line after the regulator, the coil and the 1000uF serves the DAC board!

Evaluating with a similar line cable of the NAD C541 (AKA Mr. Kanguroo) because C541 skips sometimes with CD-R, except CD-R from Verbatim!
But i'm dealing with this "smart but"

When i get more news about "Kanguroo" i'll report!

Regards
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Old 17th November 2008, 12:58 PM   #20
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Another vote for OPA2604. Try with a 1uf tantalum+100nF film capacitors bypass between pin 4 and 8 (be careful with tantalum as it's polarized: pin 4 is negative, pin 8 is positive).
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