Well, I thought I would take on a small (and hopefully inexpensive) project while I continue to work on the amp. I have a Sony ES DVP-NS9100ES SACD/CD/DVD player that I only use for the CD/SACD portion. I cracked it open the other to take a look to see what I could possibly do to make it better. As you can see, most of the components are SMD type devices so it would appear....very littile. I don't have the skill or tools to desolder/solder SMD devices. Because of that the clock and DA converters are out of the question. Here are some pictures. Power board 1 Power board 2 Audio board Schematic The caps I think I want to change. Most are coupling or decoupling. Most of these caps are what appear to be orange drop caps with the exception of the bigger electrolytic output caps. I have some ideas of what I might replace them with but I would like to hear what others might have to say. Especially if anyone has worked on one of these machines. Thanks in advance for any input.
One more pic of what it will look like minus veneering and tracks to move in and out and up and down adjustments. I just finished the 2nd cab for prefit, so everything is ok to move on to the next phase of the build which is the Z19 Xover build. I will be starting off with ERSE caps that I bought a few years back and take it from there. I have had great results with ERSE caps and shouldn't need anything more than those.
It all looks very good as is, you could look at the feedback caps and resistors, wherever there's an OpAmp and a low value cap between output and input eg c241,256 on the mix amp. Only change them if they are lacking, I'm not sure if orange drops are lacking though, and same value only. Perhaps change the resistors leading up to the outputs. Possibly add 1nf to the 100nf across the power rails of each OpAmp. Silmics are very good, audio note seiryu might be a step up though or polymer.
Kinda what I thought. The things I would like to change are SMD's so I dont dare. The orange drop are things I can change but what brand has the right values and the right size (they are very small values). I had looked at some of the Amtrans caps....but are they actually a step up from the orange drops...not sure. The Silmics I think are the originals..not the version II. I had looked at the Audio Note but are they a step up over the Silmics...idk. The other thing I was looking at was bypassing them with a Vishay 1837 or something like that.
If it were me I would leave the Orange drops alone for now and fit 100uf Nichicon Polymers in the 47uf coupling capacitor position. They are small so will fit easily and have lots of benefits. If you didn't like them you could swap them out easily enough. The Audio Notes are better than the Silmics IIs with no break in but not as good as Polymers. I have used them all in CD Players most are documented further back in this thread where I committed sacrilege by replacing Black Gate with Polymers in the Rotel RCD855 and I used Audio Notes in the Philips CD753.
I like the real world experience guiding your suggestions. Sounds like a good plan. Thanks for the advice!
Just a quick comment, you are both saying Orange Drop for the small film caps, I guess as just a generic film capacitor term since they are kind of orange in color, but Orange Drop was a specific capacitor line originally made by Sprague, then Vishay, and now CDE, and the caps in the picture aren't them. You'd have to post a closeup of the label area on one of the caps to see what looks like the manufacturer emblem, then could better trace what they actually are by the size. But I'd agree, they are likely decent capacitors, I think you would get much bigger gains by replacing those 47uF electrolytic coupling caps with some decent film types, around 5uF should be enough, the load on the outputs is 220k in parallel with your preamp input impedance. Some type of quality low voltage metalized polypropylene is probably the only option to fit within the size constraints.
Another path that many have chosen in the past is to measure the actual DC voltage at the output of the last opamp before the coupling capacitors, and if it is low and stable enough, just jumper the coupling caps.
I have been thinking about doing this with my phono preamp. I did it with the Pyle PP999 and the bass was notably improved (but those were smaller caps at the time). I measured only a few milliamperes after removing those output caps, and my next stage (the Parasound ZPre but now the MiniDSP 2x4 HD) had input caps anyhow. So before I make my V2 board, I'll remove the output caps or at least take another measurement and decide if I want to include them. I may also replace the 100uf electrolytic that is in the feedback loop with 7-10 10uf polyester caps wired in parallel (I can use LTSpice to figure out how much capacitance I need to maintain the LF performance).
Usually the big electrolytic capacitor in the feedback loop is to reduce the gain at DC to just 1 so you don't amplify the input offset voltage, and yes, that has always been someplace where better caps improve the sound. Often in the past, the polarized electrolytic was replaced with back-to-back electrolytics to make it non-polarized, and then it was bypassed with a good film cap. It may not be feasible to replace it solely with a film capacitor due to the relatively low value of the feedback shunt resistor that it is working with, but again, you can test it with it shorted to see if you are amplifying any DC, depends on the input stage, but you have to be careful, not so much in a phono stage, but a power amp can cause damage Back when I was designing a power amp, I went through all those stages, at first using the big feedback capacitor, with upgrades to make it better, then a DC servo and finding it affected the sound quite a bit, then making it DC coupled with a trimmer and being shocked how much more lifelike it sounded, and ultimately getting rid of the feedback altogether. But gets more complicated at each of those stages due to need to trim and drift. I finally built a servo system for a no feedback amp that worked by shunting some of the input stage bias current with a substantial deadzone where it did nothing, so purposely biased it with some positive offset, and that's what I wound up using in my DAC, with output stage shown below. It was pretty transparent. Ignore all those TVS diodes, I was using them a lot back in those days as junction capacitors, really good sounding, the 15V ones were around 850pF, but of course you have to be careful where you use them due to the voltage, I used a lot of 150V ones too, think they were around 100pF. The bigger 0.1uF caps were Wima MP3-X2 vacuum epoxy impregnated paper film, and the 4.7uF caps on the servo were the small 5mm lead spacing Wima mylar box caps. This was a fairly high biased single-ended output design..
It is a nonpolarized bypassed with a poly cap as it stands. I'm honestly not sure I'll like the sound of polyester caps more or not. It is such a stupid simple design, it has no right to sound as good as it does.
More than what? More than the electrolytic? Yea, it's a tough call sometimes, unless your system is devoid of all that electrolytic signature sound (and that part is very subjective anyway, but for me very significant), just changing one electrolytic for a polyester cap in a feedback loop filter may not really improve the sound, you may perceive a loss due to the higher cutoff frequency. Film caps aren't perfect either, they come in many flavors. No crime in liking what you have now
You got it right, I'm not sure if I'll like an army of polyester caps more than the NP electrolytic + polypropylene bypass. The nice thing in such a stupid simple design is that it will only cost $75 to find out.
Do you test the frequency response and distortion at all? I guess it's based on a tested design, right, so probably pretty good specs?
I haven't tested it, it is the OPA164x technical notes design. The components for RIAA they specified are theoretically ideal, and I used 1% components. I thought I should try testing it, but a lot of the inverse RIAA devices are "only" +/- 0.5dB, and according to LTSpice it may be as good as +/- about 0.1dB from 40-20k. Wynn Palmer @ AudioKarma said this about the PP999 (very similar) design: The circuit as drawn is nominally 1.4 dB p-p 20 Hz-20 kHz. The gain is 40.1 dB at 1 kHz. C4 does set the LF cut off frequency. with 100 uF it is at c. 12 Hz, and with 220 u it is at c. 5.7 Hz, as expected. OPA1641/2 has a GBW product of 11 MHz. That means that the feedback factor is 141-20-86= 35dB at 20kHz. Decent enough, but c. 15dB less than my target value. I'd expect a 20kHz THD of about 0.002% just from the opamp for a 1v rms output (12 dB above the 2.5 mv input rating). The A-weighted output noise with a shorted input is 30 uv. With the cartridge attached it is 60uv. Relative to the 12dB above rated input of 2.5mv (assumed) of 10mv, with a resulting output of 1v the A-weighted S/N ratio is 90.5dB for a short and 84.5dB for the cartridge. If I do build V2, maybe I'll try getting Amir @ Audiosciencereview to subject V1 to his Audio Precision analyzer. I'd be interested to see real world #'s for RIAA compliance, noise, distortion, and maximum input/output.
I knew that Vishay and Sprague made caps under that name, I did not know CDE was now doing that as well. Here is the best closeup I could get. I agree the Silmic's, as good as they are for an electrolytic, are the offending pieces at this point. I was doing the math on the cap size. I have a 1M input resistor and either a 25k or 50k (can't remember at this point) stepped attenuator and with the 220k output resistor and only a 5uF cap the corner frequency is between .9Hz and 1.7Hz. A 5uF cap if I can make one fit should do just fine for me with the Broskie preamp.
Interesting. I will see if I can get a measurement on this. What is better than a good cap? No cap if you can get away with it. What are your thoughts on Q117 and Q118 near the end of the line. Could they be muting transistors? If so, I have heard in some cases removing them can improve sound a bit.
You can always just use REW and your audio interface. You can do a loop calibration in REW for your audio interface, and you can use a reverse RIAA calibration file on either the phono stage input or output (I generally use it on the input, so RIAA calibration file on the audio interface output, and loop calibration file on the input). It does frequency sweeps and generates the response and noise/distortion measurements/plots. I posted some measurements from one of my DIY phono versions earlier, but below is a the response and distortion pages of my Phasemation EA-200. Response isn't quite as flat as my DIY, looks about +/-0.25dB, but low frequency distortion and noise is a little better, depends on output level, neither design uses a negative feedback loop so distortion will rise at higher output levels, moreso on my simple design. Sounds like yours is probably fine...
Looks like they are probably Nissei Electric caps, big Japan company, maybe the polypropylene film APS style, should be good quality and decent sounding caps, you could measure the dimensions of one and compare it to the chart at ... NISSEI ELECTRIC
Yea, polypropylene film/foil caps are gonna be just about the best for that application, can't easily do much better for audio filters. Metalized ones would be quite a bit smaller, but not as good for performance or sound quality.
Now I will turn my attention to the 47uF electrolytic to see if I can find a 5uF film cap that I can make fit.
Are you doing all the channels, or just the main stereo output? The output electrolytics in your picture look really big for 47uF @ 63V, must be the old school type, not the awful sounding miniaturized style that everyone uses now, so could probably fit some 5uF metalized polypropylene caps in there, about the same diameter if you get some lower voltage 63V or 100V types. I'm not too up on the latest and greatest there, I use mostly vintage stuff, or some new film and foil types, but some around here have some strong preferences and could steer you in the right direction, if you need it.
