Introduction to the Zero DAC and Headphone amplifier.
Posted 09-17-2008 at 12:30 AM by Currawong
Updated 04-06-2009 at 11:47 AM by Currawong (Fixed a couple of things.)
Updated 04-06-2009 at 11:47 AM by Currawong (Fixed a couple of things.)
Tags zero dac
Jan 2009: After the issues people have had receiving faulty Zeros, we have asked the maker of the HDAM upgrade to design an alternative to the Zero. This is now known as the Compass. You can read the Head-fi discussion about the design. This is likely to be available from February and, though it's a bit more expensive than a fully upgraded Zero from Lawrence, it is made to much higher standards.
April 2009 Edit: This guide is merely for information only. It's not a recommendation for the Zero. Due to its poor reliability, buying it is not recommended.
What is the ZERO?
The ZERO is a Digital to Analogue converter (DAC) and headphone amplifier/preamp made in China that has become popular on head-fi.org due to its low price (US$99 for the basic unit) and that it can be upgraded for around the same amount for a huge improvement in sonic quality.
The ZERO's product page from Tianyun100 (in Chinese).
Where can I buy it?
The Zero is available on eBay (click here for a direct search link). People have reported good experiences buying from wsz0304 on eBay. If you don't want to use eBay, the unit from Lawrence. He can be contacted at lawrencechanbig ((%)) msn.com. (Replace the obvious with an @ symbol). As of late October 2008, a few people have reported that their units from Lawrence arrived defective or not with the options requested and difficulty in resolving these issues.
What can it do?
The ZERO, internally, consists of two parts: a DAC, which can convert a digital signal, either coaxial or optical, into an analogue signal, and a headphone amp + pre-amp that can be used with either headphones or a power amp, headphone amp or powered speakers.
Normally, only the DAC section is in operation, with output going straight to the rear RCA jacks. If the Preamp button is pressed, the output goes through the amp/pre-amp section as well, controllable with the volume knob. If headphones are plugged in and the Preamp button is pressed, the ZERO becomes a headphone amplifier.
How can I connect it to my CD player or computer:
You have only two choices of connection to the ZERO: Optical digital, using a plastic or glass TOSLINK cable, or a coaxial digital cable with RCA connections. Many CD players have both of these as an output options. Many sound cards have optical digital outputs, as well as "SPDIF" coaxial digital output. Some improvement in sound quality will result from using a good quality coaxial digital cable, such as from Blue Jeans, or a quality glass optical cable instead of the one that comes with the ZERO. Penchum found a good quality glass optical cable which I need to find the link for.
What upgrades are possible?
To understand this, we have to take a look inside the unit. Inside, you will see three main parts, the large transformer, the large circuit board for the DAC and a smaller circuit board for the headphone/pre-amp.
OPAMP upgrades:
On the larger DAC board is a removable chip known as an OPAMP. On the headphone/pre-amp are two OPAMPs. These chips are essentially the equivalent of a bunch of transistors and amplify the signal. Since they are presumably cheaper, use less power and are more compact to manufacture, they are often found on audio cards, in CD players and other audio devices. The 3 OPAMPs in the ZERO are "dual" OPAMPs, that is, amplify two channels. This is important to know, as there are "single" OPAMPS as well. These OPAMPs can be replaced with better quality ones, resulting in a much better sound from the ZERO.
The current best all-round recommendation from Penchum's testing is to use two Burr Brown OPA627 OPAMPs in the DAC and two LT1364 OPAMPS in the headphone/pre-amp section. WAIT, yes, I did just say "two" OPA627's, as they are single OPAMPs, you'll need an adaptor to use them in the slot, known as a Brown Dog adaptor.
Your OPA627s may be the soldered version and not the socketed version and look like this, with the second chip underneath:
The sound signature of the OPA627 was described by Penchum as being "tube-like". It's gives a rather warm, but still very detailed sound.
Luckily, Lawrence sells an upgraded ZERO for US$275 (including shipping, but note this might vary depending on which country) which includes these better OPAMPS, better volume control saving those of you who just want to buy a nice unit and listen to music without taking off the cover and fiddling an easy option.
Other people have experimented with "OPAMP rolling" - experimenting with many different combinations of OPAMPs in the ZERO, but the purpose of this guide is not to get into that. If you're interested in doing that, there are a great many you can get free samples of and try.
Volume Pot Upgrade:
The default volume pot in the ZERO is a cheap and somewhat nasty Chinese unit which is known to often be imbalanced at low volumes and even give a bit of hum and hiss. Unfortunately the only replacement known of at this stage is a NOS (New Old Stock) ALPS pot from Japan which Lawrence has a number of. If you've already got a ZERO, replacing the default one will require soldering skills. Otherwise, if you order the upgraded ZERO from Lawrence, you can order the better volume pot for an extra $20.
OPAMP replacement with a HDAM:
Not to confuse the HDAM with what Marantz created, it's a different thing, a HDAM unit replaces an OPAMP altogether with, get this, transistors! That's right, one of the best upgrades you can make to the ZERO is to replace the thing that replaces transistors in the first place, with what it replaced! Confused yet?
The idea came from the Burston HDAM unit that is often used to upgrade CD players in the same way. However, while the Burston unit is a little expensive, the Chinese manufacturer of them, Audio-gd, is not, and you can buy not only the same unit Burston sells, but a newer model with a slightly different sound signature. The older, but more neutral sounding module is known as the Earth. The newer module is called the Sun.
The problem with these units is, as they are vertically-mounted circuit boards (once they are plugged into your OPAMP slot) the cover of the ZERO wont fit back on. As a result, both Lawrence and Audio-gd sell versions that include a 10cm or so long set of wires so that the HDAM can sit elsewhere in the case. Though the units weren't originally designed to be used with extension wires, there have been no reports of problems.
Currently, replacing just the DAC OPAMP with a HDAM is recommended. You can try replacing the pre/hp amp opamps with HDAMs. IMO it's a bit overkill, as the money would be better spent on a dedicated headphone amp, such as one of the Audio-gd models. If you've bought an upgraded ZERO, replacing the pair of OPA627's with a dual-HDAM unit is the go. Feel free to experiment though. All three opamps in the Zero are dual/double opamps.
If you have a soldering iron, connecting the earth wire of the HDAM to the earth leg of the RCA jacks is something I recommend, as it improves the SQ, giving it more accuracy and punch. No soldering iron? You could just use an alligator clip. Edit: This is NOT necessary to do. Also, attaching the ground wire to any of the chassis screws is not recommended as the HDAM becomes quite hot. If it's too much hassle, just leave the ground wire not touching anything.
The unnecessary capacitors:
An interesting find on the web is a site called The Lampizator. In it, the owner does some quite crazy modifications to his Zero in the name of better sound. However, while we aren't interested in the really crazy stuff, one of the mods is quick, easy and only requires a small pair of wire cutter or even strong scissors and is well worth it, scary as it sounds.
As stated on the Lampizator site in the "bad points" about the Zero: "The output RCA are connected to noise killing caps which shouldn't be there at all." If you snip off these caps, the muffled treble of the Zero will clear up considerably, opening up the top end. There is no downside to this modification, except voiding your warranty (though return shipping would probably cost as much or more than the unit itself anyway).
Note: Myriad felt that after snipping these caps, the sound was too bright for him with his Grados. Grado owners might want to keep this in mind as they are reputably bright headphones.
Headphone compatibility:
The ZERO has enough grunt to drive low or high impedance headphones, however remember that the headphone amp built in is very basic. With low impedance cans such as the AKG K701 and Denons, the result is rather good, though not with as much spaciousness and separation in the sound as you'd get with a dedicated amp. If you've been listening out of a crappy PC soundcard and switch to a ZERO, it will be a massive improvement. The ZERO will make do if you have good headphones and haven't yet heard better, but wont in any way compare to adding a good few hundred dollars worth of amp will.
Can I put my amp on top of the ZERO:
It's probably not a good idea unless, like me, you have a slow spinning fan blowing air across the units. The ZERO heated up my Little Dot MKV quite impressively before this.
Summary:
The basic ZERO unit:
US$99
DAC OPAMP: B-Brown OPA2604
HP/pre OPAMPs: ?
Volume pot: "Song" (China)
The upgraded ZERO: (Lawrence's version)
ZERO DAC
DAC OPAMPs: Burr Brown OPA627
HP/pre OPAMPs: LT1364
Volume Pot: ALPS (Japan)
The upgraded ZERO: (wsz0304 version)
ZERO DAC
DAC OPAMPs: Burr Brown OPA627
HP/pre OPAMPs: NE5532 (original)
Volume Pot: Song (original)
The "as far as you can go without soldering" ZERO:
ZERO plus a HDAM unit with extension wires.
DAC OPAMP: Audio-gd Earth or Sun, or Moon.
How does it compare to other DACs?
April 2009 Edit: This guide is merely for information only. It's not a recommendation for the Zero. Due to its poor reliability, buying it is not recommended.
What is the ZERO?
The ZERO is a Digital to Analogue converter (DAC) and headphone amplifier/preamp made in China that has become popular on head-fi.org due to its low price (US$99 for the basic unit) and that it can be upgraded for around the same amount for a huge improvement in sonic quality.
The ZERO's product page from Tianyun100 (in Chinese).
Where can I buy it?
The Zero is available on eBay (click here for a direct search link). People have reported good experiences buying from wsz0304 on eBay. If you don't want to use eBay, the unit from Lawrence. He can be contacted at lawrencechanbig ((%)) msn.com. (Replace the obvious with an @ symbol). As of late October 2008, a few people have reported that their units from Lawrence arrived defective or not with the options requested and difficulty in resolving these issues.
What can it do?
The ZERO, internally, consists of two parts: a DAC, which can convert a digital signal, either coaxial or optical, into an analogue signal, and a headphone amp + pre-amp that can be used with either headphones or a power amp, headphone amp or powered speakers.
Normally, only the DAC section is in operation, with output going straight to the rear RCA jacks. If the Preamp button is pressed, the output goes through the amp/pre-amp section as well, controllable with the volume knob. If headphones are plugged in and the Preamp button is pressed, the ZERO becomes a headphone amplifier.
How can I connect it to my CD player or computer:
You have only two choices of connection to the ZERO: Optical digital, using a plastic or glass TOSLINK cable, or a coaxial digital cable with RCA connections. Many CD players have both of these as an output options. Many sound cards have optical digital outputs, as well as "SPDIF" coaxial digital output. Some improvement in sound quality will result from using a good quality coaxial digital cable, such as from Blue Jeans, or a quality glass optical cable instead of the one that comes with the ZERO. Penchum found a good quality glass optical cable which I need to find the link for.
What upgrades are possible?
To understand this, we have to take a look inside the unit. Inside, you will see three main parts, the large transformer, the large circuit board for the DAC and a smaller circuit board for the headphone/pre-amp.
OPAMP upgrades:
On the larger DAC board is a removable chip known as an OPAMP. On the headphone/pre-amp are two OPAMPs. These chips are essentially the equivalent of a bunch of transistors and amplify the signal. Since they are presumably cheaper, use less power and are more compact to manufacture, they are often found on audio cards, in CD players and other audio devices. The 3 OPAMPs in the ZERO are "dual" OPAMPs, that is, amplify two channels. This is important to know, as there are "single" OPAMPS as well. These OPAMPs can be replaced with better quality ones, resulting in a much better sound from the ZERO.
The current best all-round recommendation from Penchum's testing is to use two Burr Brown OPA627 OPAMPs in the DAC and two LT1364 OPAMPS in the headphone/pre-amp section. WAIT, yes, I did just say "two" OPA627's, as they are single OPAMPs, you'll need an adaptor to use them in the slot, known as a Brown Dog adaptor.
Your OPA627s may be the soldered version and not the socketed version and look like this, with the second chip underneath:
The sound signature of the OPA627 was described by Penchum as being "tube-like". It's gives a rather warm, but still very detailed sound.
Luckily, Lawrence sells an upgraded ZERO for US$275 (including shipping, but note this might vary depending on which country) which includes these better OPAMPS, better volume control saving those of you who just want to buy a nice unit and listen to music without taking off the cover and fiddling an easy option.
Other people have experimented with "OPAMP rolling" - experimenting with many different combinations of OPAMPs in the ZERO, but the purpose of this guide is not to get into that. If you're interested in doing that, there are a great many you can get free samples of and try.
Volume Pot Upgrade:
The default volume pot in the ZERO is a cheap and somewhat nasty Chinese unit which is known to often be imbalanced at low volumes and even give a bit of hum and hiss. Unfortunately the only replacement known of at this stage is a NOS (New Old Stock) ALPS pot from Japan which Lawrence has a number of. If you've already got a ZERO, replacing the default one will require soldering skills. Otherwise, if you order the upgraded ZERO from Lawrence, you can order the better volume pot for an extra $20.
OPAMP replacement with a HDAM:
Not to confuse the HDAM with what Marantz created, it's a different thing, a HDAM unit replaces an OPAMP altogether with, get this, transistors! That's right, one of the best upgrades you can make to the ZERO is to replace the thing that replaces transistors in the first place, with what it replaced! Confused yet?
The idea came from the Burston HDAM unit that is often used to upgrade CD players in the same way. However, while the Burston unit is a little expensive, the Chinese manufacturer of them, Audio-gd, is not, and you can buy not only the same unit Burston sells, but a newer model with a slightly different sound signature. The older, but more neutral sounding module is known as the Earth. The newer module is called the Sun.
The problem with these units is, as they are vertically-mounted circuit boards (once they are plugged into your OPAMP slot) the cover of the ZERO wont fit back on. As a result, both Lawrence and Audio-gd sell versions that include a 10cm or so long set of wires so that the HDAM can sit elsewhere in the case. Though the units weren't originally designed to be used with extension wires, there have been no reports of problems.
Currently, replacing just the DAC OPAMP with a HDAM is recommended. You can try replacing the pre/hp amp opamps with HDAMs. IMO it's a bit overkill, as the money would be better spent on a dedicated headphone amp, such as one of the Audio-gd models. If you've bought an upgraded ZERO, replacing the pair of OPA627's with a dual-HDAM unit is the go. Feel free to experiment though. All three opamps in the Zero are dual/double opamps.
If you have a soldering iron, connecting the earth wire of the HDAM to the earth leg of the RCA jacks is something I recommend, as it improves the SQ, giving it more accuracy and punch. No soldering iron? You could just use an alligator clip. Edit: This is NOT necessary to do. Also, attaching the ground wire to any of the chassis screws is not recommended as the HDAM becomes quite hot. If it's too much hassle, just leave the ground wire not touching anything.
The unnecessary capacitors:
An interesting find on the web is a site called The Lampizator. In it, the owner does some quite crazy modifications to his Zero in the name of better sound. However, while we aren't interested in the really crazy stuff, one of the mods is quick, easy and only requires a small pair of wire cutter or even strong scissors and is well worth it, scary as it sounds.
As stated on the Lampizator site in the "bad points" about the Zero: "The output RCA are connected to noise killing caps which shouldn't be there at all." If you snip off these caps, the muffled treble of the Zero will clear up considerably, opening up the top end. There is no downside to this modification, except voiding your warranty (though return shipping would probably cost as much or more than the unit itself anyway).
Note: Myriad felt that after snipping these caps, the sound was too bright for him with his Grados. Grado owners might want to keep this in mind as they are reputably bright headphones.
Headphone compatibility:
The ZERO has enough grunt to drive low or high impedance headphones, however remember that the headphone amp built in is very basic. With low impedance cans such as the AKG K701 and Denons, the result is rather good, though not with as much spaciousness and separation in the sound as you'd get with a dedicated amp. If you've been listening out of a crappy PC soundcard and switch to a ZERO, it will be a massive improvement. The ZERO will make do if you have good headphones and haven't yet heard better, but wont in any way compare to adding a good few hundred dollars worth of amp will.
Can I put my amp on top of the ZERO:
It's probably not a good idea unless, like me, you have a slow spinning fan blowing air across the units. The ZERO heated up my Little Dot MKV quite impressively before this.
Summary:
The basic ZERO unit:
US$99
DAC OPAMP: B-Brown OPA2604
HP/pre OPAMPs: ?
Volume pot: "Song" (China)
The upgraded ZERO: (Lawrence's version)
ZERO DAC
DAC OPAMPs: Burr Brown OPA627
HP/pre OPAMPs: LT1364
Volume Pot: ALPS (Japan)
The upgraded ZERO: (wsz0304 version)
ZERO DAC
DAC OPAMPs: Burr Brown OPA627
HP/pre OPAMPs: NE5532 (original)
Volume Pot: Song (original)
The "as far as you can go without soldering" ZERO:
ZERO plus a HDAM unit with extension wires.
DAC OPAMP: Audio-gd Earth or Sun, or Moon.
How does it compare to other DACs?
Quote:
Originally Posted by Ben Diss
I have a Zero with just an OPA624 upgrade. I've compared it to a DIYEden Great March II and to a Lavry DA10.
On a 100 scale, if an iPod rates a 5 and the Lavry a 95, then my Zero is about a 60 and the Great March II is about 85.
On a 100 scale, if an iPod rates a 5 and the Lavry a 95, then my Zero is about a 60 and the Great March II is about 85.
Total Comments 64
Comments
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Excellent job CW, very valuable info for the consumer wishing to sort out all the options...
Peete.Posted 09-25-2008 at 04:31 PM by Pricklely Peete
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CW, This is excellent work! Sorry it took me so long to come check it out. Good on ya!!
Posted 09-28-2008 at 05:45 PM by Penchum
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This is great. It address a lot queries for freshmen and also serve as some reference material for the sophomore.Posted 09-30-2008 at 11:44 AM by ccschua
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Now you only need to test the bypass mod from the Lampizator site
Posted 09-30-2008 at 11:47 PM by grkn
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Great job! Maybe people should come here first instead of the long Zero thread heh
Just a question: It looks like you're suggesting we snip off both the caps near the RCA jacks and also on the headamp... is that so? For a total of 4 caps...Posted 10-01-2008 at 02:51 PM by direcow
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Yup, that's right, 4 caps total.Posted 10-02-2008 at 12:08 AM by Currawong
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Excellent!!....Thanks for all your work...Posted 10-04-2008 at 05:56 AM by Trapper32
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Currawong -
Man, quite an effort! WTG
We really needed something like this.Posted 10-07-2008 at 07:29 AM by StratCat
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Ok, DID the bypass mod (w/o the tube), and even though the sound was.. clearer, It lacked punch, the headphone out also worked but got equally anemic.Posted 10-07-2008 at 11:48 PM by grkn
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I haven't added it, but if ignore the bypass mod and use a HDAM with its ground wire soldered to the RCA ground, you get a lot more punch and accuracy.
Thanks for all the comments.Posted 10-11-2008 at 03:56 AM by Currawong
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So, buying the basic zero with alps pot and doing the opamp upgrades yourself is the cheapest options? And would u recommend cutting of those 4 caps?Posted 10-13-2008 at 03:57 PM by K0L3N
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I'm not sure how much the OPAMPS cost in total, but I thought it was more overall than if you bought the upgraded model.
Definitely cut those 4 caps, they kill the highs and muddy the sound.Posted 10-13-2008 at 11:37 PM by Currawong
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Buying the upgraded amp with alps costs me 200$, this includes shipping. Can't wait to use it.Posted 10-17-2008 at 08:59 PM by K0L3N
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Thanks for the link to this guide it clears up some questions.Posted 10-18-2008 at 05:14 PM by MadMan007
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I've fixed up the summaries to better reflect what's available from the two main sellers.Posted 10-30-2008 at 07:24 AM by Currawong
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Thanks for the summary. I recently bought one from wsz, & he states that the DAC opamp is the OP627AU, as you describe. But in the "questions/answers" section on one of his ebay listings, he states that the 'phone OPAMP is the LT1364, not the one you describe. Could you confirm? Thanks.Posted 11-04-2008 at 04:43 PM by brady7
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I got mine from him recently and the phone opamps are the standard NE5532.Posted 11-04-2008 at 04:57 PM by MadMan007
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He might have changed it, but it doesn't say anything in his latest eBay listing.Posted 11-04-2008 at 10:30 PM by Currawong
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Can you detail what upgrades are in the $220 Lawrence model? It is not crystal clear from his auction.Posted 11-07-2008 at 03:43 AM by les_garten 
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les_garten: What's not clear? What kind of detail are you after?Posted 11-07-2008 at 03:53 AM by Currawong
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