SAA7220P/A vs. SAA7220P/B

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P-47

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Joined 2003
#1
Hello All:

I am un-clear after reading as many threads whether or not the “A” is different than the “B” version in the amount for garbage it generates, and if the noise signature in the same or different.

I have a Revox B-226 w/mods ala Panasonic FC’s, .1 smd’s etc. the in power supply and the SAA7220P/A TDA1541-S1 non/os.

This I am comparing to a B-226-S ‘stock’

When I put the SA on the +5v at the DAC (20khz-40mhz window) . The B226 has higher spikes but farther apart, many less than the B-226-s about a ratio of 20:1.

Also the signature of the SA (DAC +5v) on the B226 is almost identical to the VDD (+5v) on the B226-S’s SAA7210 before it goes back to the +5v buss via a ferrite bead (both have the bead)

So to restate my question, have I swamped out the SAA7220P/A on the
B226 and now see the SAA7210 or is the hash from the
SAA7220P/A vs. SAA7220P/B that different????.

Or did I create a hole new can of worms!

And yes I know it’s a rotten piece of SS with 24 pins but have to live with it for now.

Many thanks
Tom
 
#2
Hi, SAA7220 had 3 versions

SAA7220P/A,P/B & P/C.
P/A was the earliest version.
P/B is the middle stage, Most mature version & most people said the best.

LHH2000 was use P/B.

P/A not too detail sound. P/B most detail in three chips.

P/C was the enhance version of P/B which had a 30Khz filter but the sound will most soft than two old version.


can directly exchange.


thx

thomas
 
#10
Last edited:
#11
7220PA has a level shifter in the digital domain that hepls minimizing the distorsions of the 1541.
1541A doesn't need that artificial offset anymore, so they made 7220PB that doesn't provide that offset.

Using a 7220PB with a normal 1541 will work, but it will increase the distortion level. Not that it will matter anyway for a NOS DAC.
 
#13
More details:
Type Differences Philips SAA7220P/A, /B & /C - Marantzphilips.nl
The SAA7220P/B is an improved version of the 'A' device giving 1dB better performance in the passband of the FIR filter, achieved by using different ROM coefficients. The other difference between the two types is that the offset in the accumulator is greatly reduced (+0.05% in the 'B' compared to +5% in the 'A'). The SAA7220P/A required a +5% offset to give optimum performance when used with the TDA1541 dual DAC. However, with the 'B' version this offset is no longer necessary for optimum performance.
The SAA7220P/C has been specifically designed for better performance for satellite (32kHz) applications. Again it has a different set of ROM coefficients. They are chosen such that the transition band (0 to -50db) is much sharper than for the 'A' or 'B' versions - 14.6 to 17.0kHz (for the 'C') compared to 14.6 to 17.7kHz (for the 'A' and the 'B') at the 32kHz sampling rate. The SAA7220P/C also has the reduced accumulator offset to +0.05%.
Post filtering
The 'A' and the 'B' versions of the SAA7220 are designed to be used with a third order Thomson-Butterworth or Bessel post filter as the passband has roll-off compensation for this. For 'C' version a 4th order elliptical filter is recommended in order to give a flatter overall response.
Click to expand...
 
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