[diditmyself]

I'm running mine with bypassed DAC opamp now. Straight from the DAC output via Solen/SCR 4.7 uF polypropylene capacitors and a passive RC filter (150R/10nF). I like it better this way with a cleaner overall sound and not as soft as before. I'll be running it like this for a while and then mod the active filter and run it with OPA627 again. There was a thread at diyaudio.com about those cheap ebay CS4397 DACs, and people came up with an active filter that made sense in theory and was reported to sound good. If I simulate this in LTSpice it looks much nicer than the original filter. The only thing that has to be done is change some resistors and caps and remove a couple of caps.

It's said that sigma-delta DACs like AD1852 and CS4398 need a filter on the output, so the Lampizator mods (straight out via caps, or via a tube buffer) shouldn't be up to the job if you want to do it right. The FrankenZero mod doesn't address the design flaws neither in the headphone amp nor the output stage. The Frankenmod is rather cosmetic, just adding or upgrading caps.

 

[diditmyself]

I was too curious to find out what it would sound like with a proper active filter. It sounds like a transistor amp again. I hear the sound of different opamps. A spark of magic has disappeared. AD797 - exciting but a bit sharp, AD8599 - like AD797 but not as refined, OPA627 - warm and nice but too soft, LM4562 - correct but totally lifeless.

I guess my choice will be a passive filter, so now I'm about to order parts to make a 2nd order filter.

 

[G~mann]

Hi, I've been reading Head-Fi posts for a few weeks now, but this is my first post. Here goes... I've been wondering about the new ZERO DAC (2009 revision) with OPA627, USB and other improvements. Been thinking, what portions of the FrankenZero mod may no longer necessary? The project seems to be broken down into phases. There's been those here that's implied that portions of the FrankenZero project (in their opinion) may have been more cosmetic than significant audio improvements. I am considering the new 2009 ZERO DAC with OPA-Moon or OPA-Sun v2 upgrade. Unfortunately, I am not a DIYer. The full FrankenZero project seems like a pretty large undertaking (for me). I just wonder in pursuit of SQ improvement, if "the juice is worth the squeeze" - speaking from a modding perspective not from ZERO's past quality issues. In light of recent changes to the 2009 revised ZERO DAC, could a updated FrankenZero mod be more appropriate? Optimized, maybe even with less complexity centered around only changes with undeniable audio improvements (if such could, ever be agreed upon). Where simplicity and stability is the focus maybe more than absolute SQ enhancement. I have nothing but fascination and respect for those that came up with this FrankenZero mod. This is not a bash by any means. Reliability issues aside (for the moment) I think this new ZERO dac (at $160 delivered) is very interesting dac. It seems to offer much bang for the buck. But this here is specifically about modding (I'll leave my thoughts about other DACs for another msg.) I know many here have moved on to bigger and better but the original ZERO was once the modded dac choice of many. I'm very interested in hearing the views of those knowledgeable (devoting countless hours) with the great FrankenZero mod which along with the discreet (heavenly body) opamps from Audio-gd, help bring affordable great sounding dacs to the masses.(all be it shortlived)

 

[diditmyself]

I don't have any experience from modding DACs, this is my first one, but in amplifiers the most important upgrades, besides the topolygy, are the active parts such as opamps and transistors, and capacitors if there are any in the audio path. IMO you should always be aware of the placebo effect, especially when you build or mod stuff yourself and if you use expensive parts. Regarding the FrankenZero mods, I have some objections:

1. Claiming that by cutting the 22 pF capacitors at the output connectors (from signal to ground acting as a low pass filter with a very high cut off frequency), the treble will be increased by a magnitude isn't trustworthy. There's still a 10 nF cap from signal to ground and the capacitance is 454 times bigger than that of the 22 pF cap. The filtering is beyond the audible spectrum.

2. I'm no electronic wiz, but I think it's common knowledge that decoupling caps should have as short connections as possible, and adding those big PIO caps with long leads will introduce resistance and inductance that will probably counteract their purpose.

3. There are still electrolytic capacitors in the audio path, and most people agree to that electrolytic capacitors sound inferior to film caps.

4. The DAC filter/buffer stage looks weird, and if simulated the square wave looks really messed up and the cutoff frequency is about 100 kHz when I think it should be just above the audible range 20 kHz. The FrankenZero mod doesn't address this at all.

5. The headphone section: there are electrolyic caps at the input, and there are electrolytic caps from feedback to ground to reduce DC-offset. Since the signal is already capacitor coupled and the opamps in the heaphone amp are JFET input types with very low bias currents, no such capacitors are needed. There's a buffering stage in the headphone amp which I don't think is necessary and could be bypassed. The large values for the feedback resistors will introduce noise and could be lowered. There's a 1 Ohm resistor on the output. This will increase the crosstalk and reduce the damping factor. None of these issues are dealt with in the FrankenZero mod.

PS. The Zero is a **** to mod because of the solder they use. It's very hard to remove.

I'll be getting the parts for my planned mods in a couple of days. This will be a radical but cheap and farily easy mod.

 

[G~mann]

I won't pretend that much of this is not way over my head. But I take it that you saying that the modding should focusing on replacing the electrolytic capacitors (in both headphone & main signal paths ) with polymer film capacitors. Would this be a 1 for 1 replacement of caps? Would there still be a need to bypass any remaining caps not replaced? Most decision usually comes with tradeoffs. What would be the tradeoff of bypassing the remaining caps? Would it lose any of this present "warm" qualities with this conversion? what about stability? If I am looking at adding an Opa-Moon, would that require any other considerations in the type\rated film capacitors used? Thanks.

 

[diditmyself]

To give you an idea of what I mean. This is the simulated 10k square of the DAC buffer/filter.

Modded.

The headphone amp

And the HP amp modded

This is how the HP amp behaves IRL http://www.head-fi.org/forums/f6/zer...3/#post5769531

In my experience a peaking amp such as in the examples above sounds sibilant. Some might find it detailed. Maybe they designed it to behave and sound this way to compensate for the dull sound of cheap opamps. Maybe not. Who knows. I don't want this behaviour.

 

[pmd]

recieved my 2009 today and there is no rca signal.
digital audio cable ( coaxial )works fine.
havent tryed the the optical or usb.
got it from snow on ebay.
just emailed him and am awaiting his response.

will let you know what happens.
paul
in florida

 

[G~mann]

After reading the last 2 posts, I am finding it very difficult to justify buying this DAC. This new revision gave the manufacturer an opportunity to correct the ZERO DAC's shortcomings. It seems that did not address much more than heat issues. I don't know much at all about electronics. I'm just a frugile consumer who enjoys researching a purchase. diditmyself, you claim you are not an electical engineer, yet you found fundamental design claws that certainly should have been apparent to any manufacturer worth it's weight in salt. If not at the design\release to the orignial DAC surely at the time of revision where quality control and the overwelming need to alter and modify the original ZERO DAC were all over the forums. I did not want to spend $400 for a high quality great sounding DAC (Compass) but I surely to do want to spend $225-$300 for a modified P.O.S. DAC that might last me 6 months. They apparently still have quality control issues even in the mist of backlash and public (forum) scrutiny. It's product NAME is mud. If they don't care about their image enough to put out a quality product, I'm certainly not going to care about their product enough to buy it. Unlike diditmyself, I do not have the Know-how to correct this DAC's deficiencies and salvage it if it decides not to work in a couple months. Compass is looking very appealing now. A product designed from the ground up with the customers feedback and expectation in mind. Compass just cost so much after S&H, PayPAl fees, and custom. I'll first consider other cheaper alternates. Maybe Little Dot + Gamma DAC combo. There are so many interesting amp + dac combinations out there. Decisions. Decisions.

 

[wynshad12]

G~MANN...YOU SAID IT BEST OF ALL
i myself is here looking for answers to that supposedly goodly tianyum Zero Dac and after reading all them 82 replies to this thread from all you guys I'm thinking I'll take a pass also that been said ...subsequently i must be missing some information on the audio Gd compass? as everyone is doing import.
there this company in Chicago called pacific valve @

www.pacifacvalve.us they sell the whole line of audio Gd . and lots more good stuff and if your not from chicago no taxes, no shipping! for a lot less than import., and no customs duty as anyone check them out.

 

[inspecality]

I bought the old model zero in august 08, it has survived a few moves and still works perfectly... I am unsure why so many people have failing units.

This upgrade doesn't really offer that much more than the old model though, so I just bought an MK III as my needed upgrade.

 

[hopeless]

Quote:

Originally Posted by inspecality /img/forum/go_quote.gif I am unsure why so many people have failing units.

Simple: the pcb itself is of low quality, plus the parts are sticked on it very hastily, thus not so precisely as one would expect from a serious manufacturer

Mine had some parts (resistors and film caps) hanging from the bottom of the pcb, apparently added the last minute to fix something..

 

[laobrasuca]

Quote:

Originally Posted by G~mann /img/forum/go_quote.gif After reading the last 2 posts, I am finding it very difficult to justify buying this DAC.

well, it's simple: you have money or not? How much? That's all. ZERO is a DAC+HPamp solution for 121$+50$ = 171$ (in my case I got -30$ of rebate). As all say, it's a honest solution, with good (not superb nor excellent) design and components. You will hardly find something at this price. But if you can spend like 100$ more, you can take a two units solution, or maybe zaulu dac 2.5 or 3.0 which also include a HP amp. If you will use it for a desktop PC you can also think about the Asus Xonar STX or ST for 200$ which is an excellent DAC and nice HPamp. All in all, it's the money which make me take the zero, knowing that the HPamp section can be replaced in the future by a dedicate HP amp.

lao

 

[wynshad12]

Quote:

Originally Posted by pmd /img/forum/go_quote.gif recieved my 2009 today and there is no rca signal. digital audio cable ( coaxial )works fine. havent tryed the the optical or usb. got it from snow on ebay. just emailed him and am awaiting his response. will let you know what happens. paul in florida

hi PMD" DID YOU PAY ANY (DUTY) TO CUSTOMS ON THAT UNIT OR IS IT BELOW ALLOWED AMOUNT... as after reading LABRASUCA POST it kinda sorta make sense to get one minus customs fees. and please let us know how the analog out,optical or usb. work out.
Winston
in miami fl

 

[G~mann]

wynshad12, Thanks for the Pacific Valve tip. they have the Compass dac for $363 delivered. Still more than I wanted to spend, but doable. Especially if the do the free Opa-moon HDAM that Audio-gd is giving out the month of June. Lao brought up a good point about using the Zero primary as a DAC. I too can get it for ~ $140 delivered. But it's not as simple as "Do I have money or not" A better question would be "Will it last more than 6 months?" or "Will my RCA output not work either?" Didn't they just started selling these 2009s last month? Already 2 posts of quality concerns. diditmyself, you have heard as well as evaluated this dac. In your opinion, is the ZERO still worth it using it as a DAC alone. I have no modding experience and would only be able to do much more than adding the Opa-moon if I find that the OPA627 is not warm enough. I am coming from a Emu 0404 USB is why I am so fixated on soft warm tones. For $140 , if left unmodded would any of you (who's actually seen and heard one) recommend the 2009 ZERO to a friend? If so, for dac only usage or both? Thanks

 

[pmd]

winston - no extra charges. got it on ebay. e-paypaled it. was shipped fast. delivered to my door by usps......

snow- has emailed me and indicated he can help me fix it.
but i am working 13 hr shift back to back and wont be able to dedicate much time to this untill thursday probably.

what i heard fresh new thru the coaxial with my K-702's sounded ok.
anyway . more later.

paul