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Review: ZERO 24 BIT/192KHz DAC/Headphone Amp/Pre-Amp - Page 11

post #151 of 9242
12/14/07 at 1:41am
Thread Starter 
Quote:
Originally Posted by Hellenback View Post
Has anyone compared this to a better known portable or desktop amp? Just the sound of the amp compared to say a Hornet or a Xenos 1HA-EPC. Maybe an Arietta? Somebody must have heard at least a portable we can compare the SQ to!
Thanks to anyone who can shed some light here or even give an opinion.
All the other amps I have are tube amps, so no direct comparison there. I can tell you for sure the DAC part STOMPED all over my Entec 205.2. All I can tell you about the headphone amp section is already in the review. I've been going back and running each Opamp longer to listen again and it is a real pleasure! Even the stock Opamp sounds pretty darn good. This unit is so new, only a few at HeadFi have one. Many on order... Here is where the other thread is on the Zero: http://www.head-fi.org/forums/f5/zer...ac-amp-263482/
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post #152 of 9242
12/14/07 at 4:58pm
Regarding reading up on various Chinese websites - Google Translate does a pretty good job actually:

Translated version of http://www.tianyun100.com/index.htm
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post #153 of 9242
12/14/07 at 5:34pm
Too bad you can't buy it for 680RMB ($85). I don't know how they can make it and sell it for that price even in China.
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post #154 of 9242
12/14/07 at 9:08pm
Thread Starter 

Think Think Think

Well, I decided to stop what I was doing and put the stock Opamp (OPA2604) back in the 'ole Zero. I grabbed my HD-650s and plugged her home, and what a surprise! It sounds great!!! It is a very nice sounding Opamp. I would say its strong point would be the variety of music it sounds good with. Also, it seems more powerful than the pair of OPA627's.

Someone had asked about the two chips in sockets on the phones board, so I wrote down what I could see:

5532D
JRC
6099B

Both chips, the same thing. Can anyone tell me about them??
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post #155 of 9242
12/15/07 at 9:42am
Thread Starter 
Quote:
Originally Posted by Shopper View Post
Like I had guessed.

The 5532 close to the volume pot is almost certainly the one used as a preamplifier for the headphone amp; the farther is almost surely the pre out buffer. I would change both with probably a LT1364 for the former, and a OPA2107 the latter. For the opamp in the main DAC board, I'd like to try two AD797. (my phones= HD650)
Well, I'm part way there! I have the AD797s on the way.
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post #156 of 9242
12/15/07 at 10:18am
Thread Starter 
Quote:
Originally Posted by Shopper View Post
Beware: don't know how stable will the AD797 be in the DAC's output stage. It's more likely to work well in the headphone amp stage (in place of the 5532).

That's why I'm also considering the LT1469 (or LT1468 x2) and the LT1122 x2 (with pins 7-8 shorted, to increase its speed by 25%) for the output stage of the DAC. Or the AD845.
Wow, what would happen if they weren't stable?? I hadn't read that...yet?
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post #157 of 9242
12/15/07 at 10:53am
Thread Starter 
Quote:
Originally Posted by Shopper View Post
The AD797 is not very stable at near unity gain (which is the case for the Zero's analog stage), you see it from the ringing in the square wave response (see datasheet). In fact its capacitive load drive is quite low at unity or low gains.

Lately some people have been using it successfully in the D1's "LR" position, as a preamplifier for the output buffers - thus at a higher gain than 1. Or, say, in the Cute Beyond, under the same condition. In the Zero's output stage it'd be somewhat a different matter - don't know what would happen since I never used this opamp before. If it should oscillate, chances are that you wouldn't be aware of it, and yet, oscillation can be dangerous.

Consider two LT1122 on a Browndog, or two AD845, or maybe an LT1364, or...
Thats interesting. I'm going to try it for sure, but I guess I'll need luck on my side.
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post #158 of 9242
12/15/07 at 10:57am
Penchum: Please keep us posted how it goes with the AD797's. Have a couple on their way myself...
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post #159 of 9242
12/15/07 at 11:03am
Thread Starter 
Quote:
Originally Posted by Shopper View Post
If it sounds somewhat grainy or harsh, it may be oscillating.
Great! I'll listen for that. Now the part I hate,,,waiting! Ow well.
I can't wait for you guys to get your units! I may have a need for another one and I want to find out how much better the upgraded unit is compared to mine.
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post #160 of 9242
12/16/07 at 10:07am
Thread Starter 
Quote:
Originally Posted by Shopper View Post
Was thinking that I really want to try two LT1468 (or just a LT1469) as well. This chip has distortion below -120 dB in the whole audio band, is unity gain stable, has low 10 nA Ib, is fast (22V/us slew rate, the AD797 being 20V/us) and is bipolar (not FET). Promising indeed.

Maybe together with the LT1122's in the headphone amp section.

LT rocks
When you get yours, it will be interesting to hear which Opamp combos work out the best. I'm sure everyone watching will be interested too!!
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post #161 of 9242
12/16/07 at 10:36am
Thread Starter 
Quote:
Originally Posted by Shopper View Post
Sure.

Will try the dual LT1469 for first. It's easy to do & since it has a high specified channel separation there shouldn't be meaningful performance degradation compared to two LT1468.

LT chips have great tonality too
There ya go! How are you going to approach burn-in issues? If you swap too quickly, your impressions might not be complete?
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post #162 of 9242
12/16/07 at 11:51am
Thread Starter 
Quote:
Originally Posted by Shopper View Post
No, don't think I'll be as frenetic in practice as I'm in theory.

And btw, opamps hardly "burn in".
Ok, just checking.
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post #163 of 9242
12/17/07 at 11:31am
Hi guys, im new to this forum and joined mainly to ask a question on the zero amp. I have read all the comments and the huge review from 'penchum'. Makes a very interesting read. I recently found the amp for sale and was considering buying it. As i am aware there is a bit of a waiting list for the amp.I emailed the guy who provides them (can't remember his name as i type this) he said i have to wait ten days, similar reply to what you all got.

I intend to use the dac for two purposes:

1. To link my sony cd played to the dac and through to my graham slee solo headphone amp.

2. To link my apple mac via an optical out to the dac and through to the solo amp.

Is there any reason why this wouldn't work? Also can i link the dac in between my cd player and my sony amp to my mission speakers? Will this work fine?

Also...

I read in the review that the dac is improved by adding the opa 627 on brown dog module. Is this a well recommended upgrade on the standard amp?

Be great to hear some thoughts and opinions.

Thanks, and a big HELLO to you all!
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post #164 of 9242
12/17/07 at 12:08pm
Thread Starter 
Quote:
Originally Posted by fault151 View Post
Hi guys, im new to this forum and joined mainly to ask a question on the zero amp. I have read all the comments and the huge review from 'penchum'. Makes a very interesting read. I recently found the amp for sale and was considering buying it. As i am aware there is a bit of a waiting list for the amp.I emailed the guy who provides them (can't remember his name as i type this) he said i have to wait ten days, similar reply to what you all got.

I intend to use the dac for two purposes:

1. To link my sony cd played to the dac and through to my graham slee solo headphone amp.

2. To link my apple mac via an optical out to the dac and through to the solo amp.

Is there any reason why this wouldn't work? Also can i link the dac in between my cd player and my sony amp to my mission speakers? Will this work fine?

Also...

I read in the review that the dac is improved by adding the opa 627 on brown dog module. Is this a well recommended upgrade on the standard amp?

Be great to hear some thoughts and opinions.

Thanks, and a big HELLO to you all!
First, hello and welcome to HeadFi!! You should stick around. There is tons of interesting things here and nice folks too!
Yes,Yes,Yes, you can do everything you talked about with great results. The only thing I would recommend is that you get the unit and not modify it until you at least have 100hrs of up time with it. The stock Opamp is very nice and you may find that nothing else is needed. That first 100hrs will bring about changes you will like!!
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post #165 of 9242
12/17/07 at 12:29pm
Did you modify yours then? If you did why did you?
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