Re: Shunt reg for SAA7220
The oscon is not critical. 22uF or so (HF filtering)
With a 6 cm lead you have to filter on the beginning and the end of the wire. Did that too, @ shuntreg filter cap 1uF mkt-> "pigsnose" bead-> wiring to 7210/7220 with 22 to 100uF Oscon in series on original place with the original 1 Ohm fusible resistor. And remember: first try out only with a load resistor, before a chip fries on 11V
Good idea to add a gyrator. Tried that too on a Tent clock, build a flea PS for the tent. With that flea a tent XO can sound allmost as good as a Kwak 7. Kwak stays the winner in my honest opininon
😉
And did a thought-over in the car: will possibly design my own super reg 🙂
And found a source of Rubycon xyz 47u/35V caps from my supplier, will buy all tomorrow😀
jnewbold said:
The oscon is not critical. 22uF or so (HF filtering)
With a 6 cm lead you have to filter on the beginning and the end of the wire. Did that too, @ shuntreg filter cap 1uF mkt-> "pigsnose" bead-> wiring to 7210/7220 with 22 to 100uF Oscon in series on original place with the original 1 Ohm fusible resistor. And remember: first try out only with a load resistor, before a chip fries on 11V
Good idea to add a gyrator. Tried that too on a Tent clock, build a flea PS for the tent. With that flea a tent XO can sound allmost as good as a Kwak 7. Kwak stays the winner in my honest opininon
😉
And did a thought-over in the car: will possibly design my own super reg 🙂
And found a source of Rubycon xyz 47u/35V caps from my supplier, will buy all tomorrow😀
Re: Re: Shunt reg for SAA7220
I'd have thought you would have used ZA's? or Os-Con SP's?
I didn't think the xyz's were anything special 😕
tubee said:
I'd have thought you would have used ZA's? or Os-Con SP's?
I didn't think the xyz's were anything special 😕
Used oscon for special purposes (7220 and so)
Upgrading 25 year old caps on my 14 bit cd300 will be done with te rather good rubycons (low esr), and as supply for further experiments.😉
And the standard blue philipses are very good too 🙂
Upgrading 25 year old caps on my 14 bit cd300 will be done with te rather good rubycons (low esr), and as supply for further experiments.😉
And the standard blue philipses are very good too 🙂
Re: Re: Shunt reg for SAA7220
Thanks for comments Tubbee. I will post a pic when I have finished.
What value/size resisitor do you use as a test load?
This shunt reg is for the SAA7220 in my Rotel RCD965BX. The Rotel uses a SAA7310, not 7210, which is CMOS and draws only 35mA. I have a separate reg with a gyrator on that chip. In fact, I have 11 separate regs in the digital and analogue section. There is one reg on each supply pin (DAC has 5)
Joe
tubee said:The oscon is not critical. 22uF or so (HF filtering)
With a 6 cm lead you have to filter on the beginning and the end of the wire. Did that too, @ shuntreg filter cap 1uF mkt-> "pigsnose" bead-> wiring to 7210/7220 with 22 to 100uF Oscon in series on original place with the original 1 Ohm fusible resistor. And remember: first try out only with a load resistor, before a chip fries on 11V
Thanks for comments Tubbee. I will post a pic when I have finished.
What value/size resisitor do you use as a test load?
This shunt reg is for the SAA7220 in my Rotel RCD965BX. The Rotel uses a SAA7310, not 7210, which is CMOS and draws only 35mA. I have a separate reg with a gyrator on that chip. In fact, I have 11 separate regs in the digital and analogue section. There is one reg on each supply pin (DAC has 5)
Joe
Load can be calculated with the current used, with 180mA
R=U/I= 5/0.180 makes 27 ohm test resistor
R=U/I= 5/0.180 makes 27 ohm test resistor
Hi Ian, also in my player there is 680pf ceramic. I did just that what you say , replace the 680 pf on the 1541A with 470 pfMica, but the sound became really 'thin'. I upped it to 560 pf and still didn't have a nice soundstage.UV101 said:
So I placed the original cap back. Nice harmonious sound. Now I have a good amount of receding sound, natural timbres.
I have in the past made a DAC, with the same 470 pF Mica - and it too had that same 'thin' sound. Though on scope it was very good (much better in 'flutter' if I may say so) My conclusion: this capacitor has a hughe influence on sound and needs extra attention. Just that the female timbres improve - no, that does not help the bass in the ensemble
! albert
Interesting triode_al.
The datasheet states 470pF, but I have read that others have spotted 680pF in commercial players. Perhaps you have discovered the reason why.
I shall have to try 680pF.
Thanks for your findings!
The datasheet states 470pF, but I have read that others have spotted 680pF in commercial players. Perhaps you have discovered the reason why.
I shall have to try 680pF.
Thanks for your findings!
philpoole said:
Phil, I would be surprised if there would be a direct effect on the freqency spectrum 20-20k. However, I have seen a mention of the 1541A having slight more uneven harmonics. Might this lead to the strange effect on the sound that shows up with a too small Capacitor?
I remember having read of some high-end manufacturer that also had a 1541A player with this 'thin'sound, could it have been Accuphase?
triode al
But this cap is used by an oscillator for the DAC, and affects distortion when at the 0v crossover - or so I'm led to believe. So it may well have nothing to do with affecting the audio band, but might just improve the performance of the DAC, which could be what you're hearing.
'Thin' sound in the amplifier world normally refers to crossover distortion, so there may be a similarity there. They may be completely different forms of distortion, but they both appear in the crossover region.
If I knew the inner workings of the DAC, then I might be able to make the above sound like I know what I'm talking about!
'Thin' sound in the amplifier world normally refers to crossover distortion, so there may be a similarity there. They may be completely different forms of distortion, but they both appear in the crossover region.
If I knew the inner workings of the DAC, then I might be able to make the above sound like I know what I'm talking about!
DOS output stage
Guys
I want to move my DOS (based on Ray's design on the cd63/67 thread) into my CD960.
The 63 has a voltage output DAC and the DOS attaches straight to it.
I believe I need more gain from the I/V stage (1st opamp) in order to drive directly into the DOS.
Can anybody see what I need to do to get a little bit more from the 1st stage?
I'd really appreciate any help. I don't need specific values, just know which ones to change! 😕
Cheers Ian
Guys
I want to move my DOS (based on Ray's design on the cd63/67 thread) into my CD960.
The 63 has a voltage output DAC and the DOS attaches straight to it.
I believe I need more gain from the I/V stage (1st opamp) in order to drive directly into the DOS.
Can anybody see what I need to do to get a little bit more from the 1st stage?
I'd really appreciate any help. I don't need specific values, just know which ones to change! 😕
Cheers Ian
Attachments
If I remember... Note the CD63 is dual output, Ray's DOS uses a long tail pair to use the difference between the two signals, so I think one of the inputs needs grounding.
I would have thought the output of the first opamp circuit would be sufficient. If not, increase the resistance R560. Vout = -(Rf x Iin).
However, that would mess up your deemphasis circuit - if you're bothered. I wouldn't be. I don't think deemphasis in CDs is very common.
I would have thought the output of the first opamp circuit would be sufficient. If not, increase the resistance R560. Vout = -(Rf x Iin).
However, that would mess up your deemphasis circuit - if you're bothered. I wouldn't be. I don't think deemphasis in CDs is very common.
Well, I've just doubled the capacitance for Cosc (pins 16&17). so its 940pF. Perhaps a bit more than 680pF, but in the direction I wanted to try.
I think its made a difference, but its hard to tell. Perhaps the soundstage is bit better, minor details I haven't heard before etc.
I think its made a difference, but its hard to tell. Perhaps the soundstage is bit better, minor details I haven't heard before etc.
philpoole said:
Yep I'll need to ground one of the inputs (should have put that in the question). 😉
philpoole said:
I thought about R560 but worked on it the wrong way round, lowering the value not raising it. Basic ohms law! I should have known better!
Whats the maximum current output of the TDA? I don't want to hurt it!!!!philpoole said:
I'm sure i've also read that its not so important on CD players. What are the side effects of changing it? 😕
philpoole said:
I'll also try uping the value of the DEM cap and see if I can concur!
Cheers
Ian
Deemphasis. Well it looks like a treble boost - ish. It won't boost the treble as much as before essentially (the main feedback loop will provide a larger output, so the relative increase of the deemphasis circuit will be less).
Let me know if it makes a difference - good or bad. I'd ideally prefer to do 680pF rather than this (possibly too much), but it hasn't harmed anything from what I've heard.
It's always hard to really tell if there's a marked improvement in all this.
Let me know if it makes a difference - good or bad. I'd ideally prefer to do 680pF rather than this (possibly too much), but it hasn't harmed anything from what I've heard.
It's always hard to really tell if there's a marked improvement in all this.
Poynton, you're right.
That teaches me to talk about a circuit I saw an hour before that was not in front of me at the time. To correct what I was thinking: the caps in the feedback loop alow higher frequencies to pass, but (the bit I was dumb and forgot about) of course this is subtracted from the signal - 'cos its negative feedback, hence a treble cut.
Yeah, should keep the document open for reference next time
Although, maybe I could've got away with it if I said, yeah that's what I meant - the recording has a treble boost, so this circuit deals with that - implying it was a treble cut. However, I think being honest in this case is much better for comedy purposes.
Just spotted that second op amp (I have the document open this time 🙂 ). A fourth order filter on one opamp. Would you not have better performance if you had two second order filters, e.g 2 sallen-key or linkwitz-riley filters? I suppose it depends on what kind of filter characteristic you want, and there's one less opamp in the signal path (which has added appeal to the accountant).
That teaches me to talk about a circuit I saw an hour before that was not in front of me at the time. To correct what I was thinking: the caps in the feedback loop alow higher frequencies to pass, but (the bit I was dumb and forgot about) of course this is subtracted from the signal - 'cos its negative feedback, hence a treble cut.
Yeah, should keep the document open for reference next time
Although, maybe I could've got away with it if I said, yeah that's what I meant - the recording has a treble boost, so this circuit deals with that - implying it was a treble cut. However, I think being honest in this case is much better for comedy purposes.
Just spotted that second op amp (I have the document open this time 🙂 ). A fourth order filter on one opamp. Would you not have better performance if you had two second order filters, e.g 2 sallen-key or linkwitz-riley filters? I suppose it depends on what kind of filter characteristic you want, and there's one less opamp in the signal path (which has added appeal to the accountant).
AND, what is C802 for? Its a 22nF cap from the ground pin of the socket, to ground (in parallel to the ground wire from that pin).
Is it assuming some inductance in the ground trace or something?
I could understand a small cap from the signal to ground.
Maybe they had some budget spare from saving an opamp in the filtering stage? 😀
Is it assuming some inductance in the ground trace or something?
I could understand a small cap from the signal to ground.
Maybe they had some budget spare from saving an opamp in the filtering stage? 😀
tubee said:
Hi Tubee,
I have just finished and tested the shunt reg (with gyrator) for the SAA7220. However, I can only get 3.92V out.
I 2.13V input before the gyrator which drops 1.39V to 10.73V at Vin pin of LM317. However, the Vout is only 3.94V (stable). Too low for 7220.
I am using 6.2R for current setting resistor and have loaded the shunt reg output with 27R.
How can I adjust the Vout? My first thought was to change the zener from 4.3V to 5.3V. Is there a better way? I am happy to experiment.
Joe
I've seen a capacitor like this before at the input ground.
Someone also raised it before on another thread - that was a Philips cdp, IIRC.
Safety earth? without forming a loop.
The I/V and filter setup is the same on most early Philips Marantz eg Marantz CD50, Philips cd350, and REVOX B226S
Andy
Someone also raised it before on another thread - that was a Philips cdp, IIRC.
Safety earth? without forming a loop.
The I/V and filter setup is the same on most early Philips Marantz eg Marantz CD50, Philips cd350, and REVOX B226S
Andy
Phil, I saw the inner working in a post that mentioned Ten Pierick, evidently one of the designers at that time. seephilpoole said:But this cap is used by an oscillator for the DAC, and affects distortion when at the 0v crossover - or so I'm led to believe. So it may well have nothing to do with affecting the audio band, but might just improve the performance of the DAC, which could be what you're hearing.
'Thin' sound in the amplifier world normally refers to crossover distortion, so there may be a similarity there. They may be completely different forms of distortion, but they both appear in the crossover region.
If I knew the inner workings of the DAC, then I might be able to make the above sound like I know what I'm talking about!
http://www.diyaudio.com/forums/showthread.php?postid=1151969#post1151969
This is also something I thought of: thin being litterally the time the current source is open, sort of squeezed .
hpoe this gives some input; there are also some technical references (white papers) around on the forum.
alberti