The "mod your Zhalou" Thread - Page 9

I am curious to see your DOTFM review.

C'mon MAN... You are the chosen one.

Lol, Ori... I love the way you think... =)

Where does this rule come from - I've never heard it before. I am familiar with the principle of using capacitors of different construction and one or more magnitudes apart when decoupling power supply pins, but these are DC blocking capacitors. While I agree that Eddie's mod makes no sense, the most logical solution would be to use the largest possible film caps (assuming one was going to use capacitors at all) and ditch the electrolytics. Parallel signal paths of different lengths and through different materials is probably not the best option in this situation.

On a related note, I jumpered the electrolytics on my Zhaolu on the weekend and I found the differences (echoing others on these forums) to be more significant than any op-amp swap I have tried so far. Even my girlfriend immediately noticed the difference, which is the best litmus test I have found for audio mods (the indifferent partner who puts up with the silly search for audio nirvana).

Ben

caps

EVITAERC
Like you , I received the modified version from Eddie, the cs 4398 with Blackgate in which Eddie has de-coupled the electrolytics on the signal path with 4 Elna caps and 4 others tiny Elna caps under the board . After around 100hours and after replacing the Lt 5701 opamp with 2604 opamp The Zhaolou sound significantly better. For example , when compared to my modded Art/Dio , it gives a big soundstage an exceptional transparency . After that , I decided , as suggested by Ori and others to remove all these 8 caps . All this was done 2 days ago by a technician . To my ears , the results were deceiving . The Zhaolou became just good . Curiously and at the opposite of what others experienced , the DAC has lost all the quality fore -mentionned . In your thread , Evitaerc seems to suggest to remove the four 1uF Elna non-polar Cerafines tiny caps and keep the four 47 uf Elna caps in place . In the following thread Zdogg suggest instead to solder the legs of the Eddie-installed caps together and bypass the top caps . I am lost .What is the best thing to do with all these caps ? Knowing that Zdogg don’t have the same Elna caps does his suggestion apply to my unit ?

Question:

Is there a quick/easy way to switch the default input from opical to coax?

He has the same caps and what he suggested is merely a shortcut for bypassing them. I should know... I suggested that to him...
I posted a mod with a pic in the last two weeks.

The fundamental theory is different for capacitors used in signal coupling, but the rule holds. Of course ditching the elctrolytic completely in favour of film is the best solution, but when it is cost prohibitve to get the large film caps to do so, bypassing the electrolytic with a small cap is the next most logical step if you don't want to sacrifice the low frequency cut-off. In this sense coupling and de-coupling is similar in that you'd want different material capacitors to do different jobs. The large electrolytics will "bypass" the low frequencies, and the film will "bypass" the high frequencies. The thought is that hopefully the HF passing through the film cap will make up for the badly mangled and diminished HF from the elctrolytics.

While the "order of magnitude" rule in de-coupling is to prevent ringing, here it is to prevent the "crossover point" from messing up the signal. Like speaker crossovers, using 2 unlinke caps in the output will cause a overlaping region where both caps will be bypassing similar frequencies in similar amounts. Due to the different phase lag in the 2 caps this will ineviably cause some distortion in the crossover regieon. The "3 orders or magnitude" rule is just a rule of thumb based on trying to prevent this crossover region from lying in the critical "midrange", the 500-3kHz that most instruments make their fundamental tones, as well as subsequent significant harmonics. Usually I try to make it 10kHz or so, but that's just me. Different people will have different opinions on where thing point (or range) should be,but the underlying theory is all the same.

Here we can see why Eddie's mod doesn't make a lot of sense. The bipolar cerafine is slightly better at passing HF than a polarized one, but they are both electrolytics in the end and even exhibit similar characteristics, so it makes no sense to use both. Worse, the 1uF bypoass cap value means that the cutoff probably lies somewhere near 500Hz and lasts all the way up the frequency range until the bigger polarized cap fall off. That is phase distortions throughout most of the music spectrum! No wonder people notice such huge improvements taking them off.

I don't know what to say. I have the exact same setup as yours (took out LT5701 and put in OPA2604), but to my ears the machine sounds vastly less congested and veiled when I took out the caps. Perhaps you just like the sound of phase distortion? What amps are you using, and what headphones? I am using Gilmore Dynalo with K701.

I suggested to cut off the 4 1uF elna caps IF you don't have a soldering iron and want a quick half-way solution. Removing the caps entirely (or solder their legs together to bypass them) is still the best solution, but must be done by soneone who can solder and de-solder.

Replaced the LT1057s with OPA2604s and cut off the caps on the bottom of the board. Much better in the highs but I miss the warmth of the bottom-end. Maybe the 2604's just need some burning in. But the highs shimmer again!

I will be receiving my discrete amplifier upgrade soon and will thus open my Zhaolu...again.... At that time I want to 'fix' the Black Gate upgrade capacitor issue.

1. Should I snip off the ELNAs at the underside of the board.
2. Should i snip off the corresponding capacitors on the top side of the board instead?
3. Should I solder the legs of the underside capacitors together or desolder the lot and have no capacitors in place?

Which of these is electrically and engineering wise correct action with respect to sound and electrical performance/stability of the unit? I want the best sound, but do not want to fry the new upgraded discrete amp or my power amp (much more expensive than the Zhaolu)

I am not much into esoterica or the more arcane aspects of HiFi, so a good engineering advice focusing on sound quality is what I am seeking... nevertheless I am partial to opamp rolling and find the OPA2604AP a lot better sounding than the LT1057. I have also just bought 2 OPA2107AP and will try them shortly.

Cheers,

Victor

eVITAERC,

Thanks for your answer. I appreciate your detailed explanation. One question - for supply bypass caps, my understanding was that one value would be used to minimize supply ripple at the component, while another smaller value would be used for RFI and/or clock filtering (in the case of a digital circuit)? Clearly, as you indicated, value selection to prevent ringing would be important, as what is the point of eliminating one noise source, only to create another.


vmajor,

I would suggest that initially, you simply solder a wire across the terminals of the capacitors, effectively shorting them (and removing them from the circuit). If you decide that you do not like the result, it is a simple matter to remove the wires. If you want to clip off Eddie's add-on caps, that is probably fine as they are not part of the original circuit. If you remove all the capacitors, you will need to add shorting wires between the holes left behind on the circuit board. Is there a sonic difference between these options? I have not tried removing the caps, but I'm doubtful there's any discernable difference.

Why speculate when so many people have already tried it and said there is a significant difference?

Definitely as unbiased a test as you can get

However, could this possibly be a power/safety problem as Eddie had mentioned to someone earlier? It's hard basing all decisions off what you hear from Eddie vs. what you hear from DIYers. I'm interested in hearing more about the science of it in the coming times.

Has anyone swapped out the Texas Instruments TL082CP in the headamp upgrade module with a different opamp?

Ah, that's what that is. I thought I could see an opamp on the board but didn't know if it was or not. The discrete amp module in my 1.3 doesn't have that, it's been added in the new module. It's obviously not a opamp used kind of like a buffer as in the stock headamp or in the DAC's analog section so I can't imagine it would have much affect on the sound.