When the '87 remaster of Tales of Mystery and Imagination came out, I immediately preferred it to the orig' 76 in almost all aspects. The MOFi LP and Gold CD improved the '76, but the 2007 remaster (both versions), loudness compressed things horribly! The '87 digital remaster, ironically, sounds best on LP. More recent remasters, including 4oth anniv have bonus material. Almost 300 versions released:
https://www.discogs.com/master/4322...ion-Edgar-Allan-Poe?sort=year&sort_order=desc
Which brings us to another '87 ... the tda1387. Remarkably, no one -- ttbomk -- has preceded it with the classic SAA7220. Still testing it out in the same rig as the TDA1545/DF1704 experiment.
Results promising. Stay tuned ...
https://www.discogs.com/master/4322...ion-Edgar-Allan-Poe?sort=year&sort_order=desc
Which brings us to another '87 ... the tda1387. Remarkably, no one -- ttbomk -- has preceded it with the classic SAA7220. Still testing it out in the same rig as the TDA1545/DF1704 experiment.
Results promising. Stay tuned ...
Some notes on this experiment ....
Sonics:
The sonics are impressive, and it seems as if 7220 imparts more of that big, bold, classic Philips multibit sound than the tda1387 itself. That is, the 7220+1387 sounds very similar to 7220+1541. Still a bit early to fully contrast with the DF1704/TDA1545 experiment.
Pin connections:
Other:
The CD player has become a bit more sensitive to disc imperfections (reading over scratches, etc). Not sure why except the 7220's extra ** 180mA current drain on the 7805.
Perhaps better decoupling or tweaking transport settings -- Focus adjustments, Laser power adjustment, etc. Not sure!
** The CDB492/480/482 ( CD2000) is an unusual 1989 Philips/Magnavox model line in that they had no stock oversampling.
Sonics:
The sonics are impressive, and it seems as if 7220 imparts more of that big, bold, classic Philips multibit sound than the tda1387 itself. That is, the 7220+1387 sounds very similar to 7220+1541. Still a bit early to fully contrast with the DF1704/TDA1545 experiment.
Pin connections:
- EFAB
- MUSB
- ATSB
Other:
The CD player has become a bit more sensitive to disc imperfections (reading over scratches, etc). Not sure why except the 7220's extra ** 180mA current drain on the 7805.
Perhaps better decoupling or tweaking transport settings -- Focus adjustments, Laser power adjustment, etc. Not sure!
** The CDB492/480/482 ( CD2000) is an unusual 1989 Philips/Magnavox model line in that they had no stock oversampling.
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Had a parallel 8x 1387 (tda1541) adapter board. This one: https://www.aliexpress.us/item/3256802746954368.html
Followed some of this hookup guide (but not I2S line R's):
https://github.com/moode-player/protodac/blob/main/docs/protodac_tda1387_x8.md#22-schematic
Hooked it up as shown.
Got distorted stereo sound (both channels). Added 220uF cap across Vdd and GND. No difference--same distortion.
Re-installed single 1387 and no issues.
Any special demands on I2S or other for 8x 1387 arrangement? How about current? Or might the 8x1387 board be defective?
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EDIT!
But this 4x 1387 (tda1541 adapter) works well.
What's the magic? Why the 8x bad?
Followed some of this hookup guide (but not I2S line R's):
https://github.com/moode-player/protodac/blob/main/docs/protodac_tda1387_x8.md#22-schematic
Hooked it up as shown.
Got distorted stereo sound (both channels). Added 220uF cap across Vdd and GND. No difference--same distortion.
Re-installed single 1387 and no issues.
Any special demands on I2S or other for 8x 1387 arrangement? How about current? Or might the 8x1387 board be defective?
=========
EDIT!
But this 4x 1387 (tda1541 adapter) works well.
What's the magic? Why the 8x bad?
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I plugged the 8x board directly into the CDP 8-pin socket. So no SAA7220 adapter board.
Things improve a little, mostly in the LSB range (low volume), but when drums and gain are present, things get distored -- and the dynamic peaks are heavily distorted.
Also, even with nothing playing, medium-level "tape hiss" (white/pink noise) audible.
Things improve a little, mostly in the LSB range (low volume), but when drums and gain are present, things get distored -- and the dynamic peaks are heavily distorted.
Also, even with nothing playing, medium-level "tape hiss" (white/pink noise) audible.
The orig. diyparadise DAC had a simple resistor for I/V -- simple and passive. And then Rudolf came along and offered his schema. Didn't realize he kept an I/V R. Sneaky guy!
For R_iv , in Rudolf, I used 3.3k originally. I think diyparadise orig. suggested 3.3k for 12vdc input. But 3.3k works fine on my 15vdc pwr supply.
As photo shows, I bodged ** in another 3.3k in parallel to halve the orig R_iv values -- now 1.6k.
NICE!
Thx folks!
But is it a keeper? That is, will R_iv (prev at 3.3k, now at 1.6k) still work decently -- at 1.6k - - with single or 4x dac chips? It would be good to have some R_iv value for the Rudolf that is "universal".
(** BTW, about bodges: Just noticed, as I went into do the R_iv bodge, that I further modded Rudolf's orig I/V, but can't remember the details -- over 12 yrs ago now -- two extra trans. on the bottom of the board. Huh?? I'm sure I violated Mr. Broertjes’orig patent, and hid it on the bottom. Don't recall that dream tho'. What is that bodge thing, anyway???)
For R_iv , in Rudolf, I used 3.3k originally. I think diyparadise orig. suggested 3.3k for 12vdc input. But 3.3k works fine on my 15vdc pwr supply.
As photo shows, I bodged ** in another 3.3k in parallel to halve the orig R_iv values -- now 1.6k.
NICE!
Thx folks!
But is it a keeper? That is, will R_iv (prev at 3.3k, now at 1.6k) still work decently -- at 1.6k - - with single or 4x dac chips? It would be good to have some R_iv value for the Rudolf that is "universal".
(** BTW, about bodges: Just noticed, as I went into do the R_iv bodge, that I further modded Rudolf's orig I/V, but can't remember the details -- over 12 yrs ago now -- two extra trans. on the bottom of the board. Huh?? I'm sure I violated Mr. Broertjes’orig patent, and hid it on the bottom. Don't recall that dream tho'. What is that bodge thing, anyway???)
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What do you expect from an "universal Riv"? You sure know the simple relation between DAC output current, Riv and the resulting audio voltage level?
"Simple relation between DAC output current" Are "You sure" it's "simple" ? Considering load, impedances, etc.
I don't know. That's why I queried.
A math formula or calculator -- plug in values -- is ideal.
Say something like: https://www.digikey.com/en/resource...rsion-calculator-parallel-and-series-resistor
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BTW:
The R_iv in the schema, noted in the link I posted earlier, https://diyparadise.com/w/rudolf-broertjes-ss-iv-gain-stage/ would have worked with the 1387 8x.
R_iv = 1.5k
But this is not what the PCB kit uses -- see that same page.
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