joehpj
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Posts posted by joehpj
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On 2017/2/6 at 2:29 AM, mwl168 said:
Yes, the GRLV 18VDC rails are for the 2SK170 front-end.
what's the difference between 15V and 18V?
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42 minutes ago, spritzer said:
I've been looking at the USB input and I don't really see why it would be increasing the THD and I'm frankly more worried about the RCA input. Optical should just be thrown in a fire as it is garbage on everything but the coax has just a 75R resistor to ground and then AC coupled to the AKM chip. No transformers or anything like that and if you are using some odd cables, this could be compromised quite heavily. I'll try it but I might also go and get some 75ohm BNC's and do this properly.
The USB XMOS driver was said to deliver 88.2KHz noise into DA module. I don't know if the newest driver has already solved the bug.
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http://chihhanlin.weebly.com/2447825286272313552736215.html
Though this was written in Chinese, it was still clear Denafrips suffered from glitch and THD was not good when using USB input.
The author said switching to coaxial or SPDIF would solve the glitch and cold sound.
I assume the architecture was almost the same between the tested and the one here.
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How does this compares with gg?
Same input and output stage. I assume the over all performance would be close?
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I am not really sure because I haven't try it. :/ Those who tried it reports its a stable and well embedded solution. Also supports DSD.
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Chinese made surgical microscope are cheaper ($25K) and quality are average.
Surgical loupes are better for this job I believe. Zeiss and Pentax make nice loupes at reasonable prices. ($2K)
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I was going to build a balanced isolation transformer. But I had difficult to choose form either EI or toroid.
Regardless of price and size, which theoretically will be better (in performance)? I was planning to build around 2KVA.
Does anyone have experience?
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1 hour ago, Dusty Chalk said:
Oh, post a link, please, I would love to see a Google translate of some Chinese flaming.
please, don't waste your time. Feng always concluded in local forums that Chinese should support Chinese made products. He think a gang of American born Chinese hate him and posts on the other place are intentionally to attack him and his brand. And because other products like HE1 are super expansive and SRL is even better so the price tag is soooo reasonable.
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On 2017/1/12 at 5:48 AM, kevin gilmore said:
seems linear systems is now shipping matched p-channel duals that match the lsk689 so jfet front ends may be possible again.
I assume you are referring lsk389? And matched p-channel means 2sj74 pair would work if I could find some real ones?
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This only shows how irresponsible they are for their products.
Flagship every year?
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And you'll get two super hot BJT.
18v is way too high.
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The price has a simple reason. Fang once said he thought SRL is the best HP system in the world. So he wanted to sell no less than HE1.
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2 hours ago, spritzer said:
If there are no output transformers then this is probably similar to the WES setup, hell it might even use chokes as the output load (as that should in theory boost the voltage swing but brings in a fuck-ton of issues) but simply a quad of single ended amps which all drift like mad. Now you could drive the tubes with resistor loads off a 600V supply but yeah...it will be pretty fucking bad. No heatsinks large enough to take the current of the 300B's to be seen.
It's single ended input. Should be more like the all-triode design.
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It's said the SGL amp has single ended input. The XLR jack was internally connected single ended.
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37 minutes ago, mtoc said:
Dr Fang Bian a few days ago says the BHSE and these kinds of "DIY" or half-diy amps is the main reason that, let a lot of SR-009 get burnt, these amps are simply overpower. Should be extremely careful with, or simply avoid. And then he says his new cans, HSL, is on another level.
link plz. I can read Chinese.
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L700 has bright sound character like 009. Nice HP when paired with stax amps. But with KG amps......
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9 hours ago, kevin gilmore said:
my guess is that the transient part is all discrete, and very similar to the soekris with fewer bits. and like the soekris, opamps to do the se to balanced, and more opamps to do the filter.
there are no off the shelf 24 bit dac chips. if there was, things would be much easier regardless of their price
PCM1704 was a 24bit dac. But the ENOB was less than AD5791. Why is that different?
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Although DF1704 TI paired with PCM1704 has been outdated and surpassed by FPGA based digital filter, PCM1704 is still a very good chip even after over 10 years of production. Sad to be obsoleted. As I know, TI stopped all audio R2R chip production. So we have to look into discrete design or use AD chip sth like Schiit used. Even for AD5791, it is only 20bit so when playing 24bit data, some calculation must have to be done.
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Pcm1704 has been NRND for several years. And recently got removed from the website. Audio gd still got some to make new dacs. But I think this is the last batch they could make.
Resistors and solder joints exposed in air will be influenced by humidity, oxidation. Some will drift slightly over years. I don't know if every resistors will.
Single chip w/ laser trimming would be better solution in terms of stability. IMO.
Discrete however provides better flexibility of design. And the overall performance is not only limited by dac module/chip itself.
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IMO, if people are asking for precise resistors, and they should go to single chip like 1704 or what schiit uses. All resistors are laser trimmed and packed together to avoid different voltage drift. Discrete design can never reach the level of precision of single chip.
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5 hours ago, Remolon said:
Not exactly. Suppose we need 100R.
Paralleling two 200R: 200R + .5% = 201, in parallel 100.5R, exactly 100R + .5%, Although with less probability of the maximum error.
updated information. My bad.
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it will lower the average error. Not in extreme cases just like you said.
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This module use .5% resistors in parallel to get .25%. So it's not too far from .2% Soekris used.Edit: .1% in parallel to get .05%. Wrong information. My bad.
KG said Soekris module used wrong switch and caused some problem. The overall design was flawed. Can't find the comment now. I don't know if this is better.
Also, the original OP based buffer of Soekris sounds like shit. A separated buffer was needed.
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KGSSHV Carbon Build Thread
in Do It Yourself
Posted · Edited by joehpj
This is a small project paying tribute to stax mafia. So I called it stacked mafia.
I am going to build several amps in the same boxes.
This is the first one. The Carbon with two boxes, GRHV, GRLV, 23 stepped VR.
Planned by my friend and I and built by @ang728.
Here are some pics. One GG is also done and more amps are in progess.
photo credit to ang728