Massdrop Objective 2 (O2) Headphone Amplifier

JimmyNgai

terencelaw 發表於 2016-9-18 23:55
Mayflower 02 版质量好差...

JDL 質量不錯... 做了很久, 亦有改良版...

唔知JDS Labs改良版係改良左D咩？元件用料方面有冇唔同到（我知而家新版有幾個定製選擇）？
我個JDS Labs版應該係舊版冇任何定製，連個logo都係舊式樣… 我買時有得連埋9V充電池一齊買，用左幾年so far充/放都冇問題。

原作者（NwAvGuy）幾年前已經o係網絡世界消失左，唔知佢係用咩方法"加持"Massdrop版O2呢？
據說Massdrop版係made in China，我想知佢係咪跟足所有原作者列出o既元件去造呢。

CHING有Massdrop版，你老友有JDS Labs版，如果有機會做個AB對比就好啦
我都想知我聽到o既差別係咪真，定係我心理作用或者係周邊元件問題（e.g. 火牛、充電池、過機線）

terencelaw

JimmyNgai 發表於 2016-9-19 03:33
唔知JDS Labs改良版係改良左D咩？元件用料方面有冇唔同到（我知而家新版有幾個定製選擇）？
我個JDS Labs ...

Mr. Will from massdrop 有確認 desktop 版符合原作:

https://www.massdrop.com/profile/Will/comments/289524

Massdrop o2 是MIC, 我用了9~10 月, no complain. JDL 是說在美國組裝！雙倍價錢... 我推介 Massdrop 版作為對
NwAvGuy 的致敬。擁有他的作品

您說得對, NwAvGuy 在網上消失了... 但1年前我見過 Mr. Will 說有法跟 NwAvGuy 聯糸... 大家有心求証可慢慢找他的 comments.

https://www.massdrop.com/profile/Will/comments

太多了, 我當時看完, 沒 capture 留檔。

我近期有太多嘢玩... A-B 比較 隨緣啦, 聲音有分別, 就算同牌同model , 亦可能有區別... 太多變數了。100 美金的 HP AMP, 真的連個接線個頭也買不到, 對於新手、初哥, 這 AMP 是性價比好高。高手是不會接受的, 因為太 cheap.

JimmyNgai

terencelaw 發表於 2016-9-19 08:28
Mr. Will from massdrop 有確認 desktop 版符合原作:

https://www.massdrop.com/profile/Will/comments/ ...

謝謝Terence師兄的資訊

看到Mr. Will @ Massdrop有確認O2元件符合原作咁我都放心：

Q: Is this the original O2 with all NwAvGuy’s approved parts?
A: Yep! All parts used in the production of this O2 are from NwAvGuy’s original BOM (other than the metal case, and metal volume knob, those are both custom parts we had manufactured)

翻看Will @ Massdrop的comments時發現有D料佢係選擇左"upgrade"(係NwAvGuy建議之內)︰
https://www.massdrop.com/profile/Will/comments/260225

Couple things worth noting, the volume knob is one piece of custom machined metal, the potentiometer is one of NwAvGuy’s specified upgrade options which delivers nearly zero channel imbalance (all standard O2s have very noticeable channel imbalance at low volume levels), and we’ve replaced film components with ceramic components where the BOM specifies the ceramics offer an upgrade. In short, we picked the best parts possible given what’s specified in NwAvGuy’s BOM.

NwAvGuy個blog都有提到呢點︰
http://nwavguy.blogspot.hk/2011/08/o2-details.html

C6 & C7 – These have been the same 0.22 uF film caps used elsewhere in the O2 which have been working fine for hundreds of O2 builds so far. The 7812 regulator does not require any capacitor on the output and most datasheets for the 7912 also at least imply the capacitor is optional. But for the National LM7912, the data sheet says a 1 uF capacitor is required. I suspect this is just National being more conservative than their competitors, but just to be safe, you may want to use 1.0 uF ceramic MLC caps in this location such as the part used for C1 or, even better, the 5mm lead space version specified in the latest BOM spreadsheet.

Volume Control Taper – The Alps volume controls are available with two different tapers. I have tested both the “3B” taper (used for the measurements in the first article) and the “15A” taper and I prefer the 15A as it’s more “spread out” more below 70% volume. Which you prefer depends on if you’ll be listening more at high volume or low volume settings. At low volume settings (below 70%) the 15A is better. Click the graph for a larger version (graph courtesy Alps). For most the 15A taper (the default RK09712200MC part in the BOM) is probably the better choice.

咁睇黎為左求證，我係要去問下JDS Labs有冇用到呢D "upgrade"料先得

JimmyNgai

terencelaw 發表於 2016-9-19 08:28
Mr. Will from massdrop 有確認 desktop 版符合原作:

https://www.massdrop.com/profile/Will/comments/ ...

100 美金的 HP AMP, 真的連個接線個頭也買不到, 對於新手、初哥, 這 AMP 是性價比好高。高手是不會接受的, 因為太 cheap.

如果NwAvGuy的信念是正確的話，真正的高手（唔會被價錢蒙蔽）應該會好接受

m82a1m40a1

我一買就Rev b所以真係唔識分別，之前睇這rev b好似係轉左op amp同有小量零件唔同
P. S. 我果部係Jdslab ODAC+O2

JimmyNgai

m82a1m40a1 發表於 2016-9-19 17:58
我一買就Rev b所以真係唔識分別，之前睇這rev b好似係轉左op amp同有小量零件唔同
P. S. 我果部係Jdslab OD ...

RevB應該係指ODAC。RevB主要係更換左電源LDO、USB receiver同DAC。

RevA's USB receiver/DAC︰TE7022L/ES9023
RevB's USB receiver/DAC︰SA9023/PCM5102A

評細資訊可以睇︰http://blog.jdslabs.com/?p=1003

JimmyNgai

問左John @ JDS Labs，confirmed佢地係跟original BOM。咁即係JDS Labs同Massdrop用的元件有D係幾唔同（original vs alternative）

Jimmy,

That's a good question. We adhere exactly to NwAvGuy's original BOM, except for the DC jack, which has was discontinued a few years ago. NwAvGuy was about to update the suggested DC jack before his disappearance. Regardless, the power input jack has no impact on audio performance.

Attached is a copy of the official O2 BOM, dated 9/14/2011 from NwAvGuy's page:
http://nwavguy.blogspot.com/2011/08/o2-details.html

You can see find several alternative potentiometers suggested on line 36. This should not impact sound quality, aside from channel balance at low volumes.

Ceramic capacitor changes can have a dramatic impact on power performance. As you can see, there are several capacitors on the board (lines 20, 23).

Best regards,

John Seaber
JDS Labs, Inc. | Office: (314) 252-0936 | Cell: (573) 366-0475

teamhardcore

留意返Massdrop Objective 2 (O2) 唔包兩粒9V充電池, 兩粒電唔平

deathson

teamhardcore 發表於 2016-9-21 17:57
留意返Massdrop Objective 2 (O2) 唔包兩粒9V充電池, 兩粒電唔平

直接答你，唔包，正正因為兩粒v9唔平

terencelaw

deathson 發表於 2016-9-22 21:48
直接答你，唔包，正正因為兩粒v9唔平

部機帶出街不方便, 再者 desktop 版是無位裝電芯了。

放在家聽大耳牛, 不是更好嗎?!?