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coffin
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steel
館主成員
Joined: 27 Mar 2005
Posts: 1542
Location: 高雄市
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 Posted: Fri Jun 29, 2007 10:08 pm Post subject: |
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這一版看起來應該可以成功
期待他的上市... 
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我的部落格---DIY的音響世界--- |
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ucc
大廳版主
Joined: 27 Mar 2005
Posts: 3302
Location: 台北市
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| Posted: Fri Jun 29, 2007 10:44 pm Post subject: |
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 那OP輸出電流蠻大的說 |
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狂人
極資深會員
Joined: 14 Oct 2005
Posts: 1304
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| Posted: Tue Jul 10, 2007 12:39 pm Post subject: |
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| amb wrote: | | 狂人 wrote: | | I'm wondering if MELF type resistors (looking like through-hole resistor but without the legs) are usable on Mini³ boards? Since there are some quite high quality resistors available in MELF forms (Like Vishay Dralorics MMU0102). |
If you're referring to something like these MELF resistors, there is no convenient way to solder them onto the PCB pads.
The board was laid out for 0204 through-hole (leaded) resistors with 5mm pitch. The recommended resistors have a body length of 3.5mm or 3.2mm.
Anyway, this is off-topic in the β22 thread. Further discussions about Mini³ should go to the following thread:
http://bbs.audiohall.net/viewtopic.php?t=4720 |
continuing from another thread.
I'm wondering if it is possible for the pad on Mini3 to contact the MELF 0204 resistors? Or maybe lengthening some of the pad slightly so that MELF and 0204 through hole can both be used, depending on user preference.
Just my hope anyways  Been really eager to try those resistors out |
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amb
見習員
Joined: 15 Dec 2006
Posts: 45
Location: Sunnyvale, CA, USA
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| Posted: Tue Jul 10, 2007 3:44 pm Post subject: |
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| 狂人 wrote: | I'm wondering if it is possible for the pad on Mini3 to contact the MELF 0204 resistors? Or maybe lengthening some of the pad slightly so that MELF and 0204 through hole can both be used, depending on user preference.
Just my hope anyways Been really eager to try those resistors out |
The MELF 0204 resistors are 3.6mm long with its solderable end-caps starting at 1.8mm, so it's too short to reach the 1.27mm (diameter) pads spaced 5mm apart. Also, the cylindrical shape of the MELF resistors makes them difficult to position for soldering -- they would tend to roll around.
At any rate, production Mini³ boards are already being fabricated, so it's too late to change.
A goal of this amp is to make it as compact as possible while keeping it easy to build, so aside from the opamps all other parts are through-hole. The design is tightly-integrated with a specific case, volume pot, jacks, opamps and other internal parts. The specified 1% metal film leaded 0204 resistors are excellent for this application and I don't feel that there is any tangible benefit with other resistor types.
In fact, I would strongly discourage builders from trying to "improve" the amp by substituting other parts, especially the opamps, or any other parts that might cause fitment issues. This is not an amp where you could get away from using axial-lead capacitors in positions designed for radial, or mounting oversized resistors vertically "tombstone style". The extra lead inductance from doing so could cause stability problems because the opamps are very high-speed, wideband devices which are very sensitive to layout issues. |
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狂人
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Joined: 14 Oct 2005
Posts: 1304
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| Posted: Tue Jul 10, 2007 5:51 pm Post subject: |
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| amb wrote: | | 狂人 wrote: | I'm wondering if it is possible for the pad on Mini3 to contact the MELF 0204 resistors? Or maybe lengthening some of the pad slightly so that MELF and 0204 through hole can both be used, depending on user preference.
Just my hope anyways Been really eager to try those resistors out |
The MELF 0204 resistors are 3.6mm long with its solderable end-caps starting at 1.8mm, so it's too short to reach the 1.27mm (diameter) pads spaced 5mm apart. Also, the cylindrical shape of the MELF resistors makes them difficult to position for soldering -- they would tend to roll around.
At any rate, production Mini³ boards are already being fabricated, so it's too late to change.
A goal of this amp is to make it as compact as possible while keeping it easy to build, so aside from the opamps all other parts are through-hole. The design is tightly-integrated with a specific case, volume pot, jacks, opamps and other internal parts. The specified 1% metal film leaded 0204 resistors are excellent for this application and I don't feel that there is any tangible benefit with other resistor types.
In fact, I would strongly discourage builders from trying to "improve" the amp by substituting other parts, especially the opamps, or any other parts that might cause fitment issues. This is not an amp where you could get away from using axial-lead capacitors in positions designed for radial, or mounting oversized resistors vertically "tombstone style". The extra lead inductance from doing so could cause stability problems because the opamps are very high-speed, wideband devices which are very sensitive to layout issues. |
Understood, personally, I do not like to mount resistor tomb stone style, nor do I like to use axiel in places where they do not belong. So that would not really be a problem for me.
OP-amps, well seeing your message gave me the feeling that it was a PITA to pick the proper amp and tune it properly, so I won't change that either.
I'm just REALLY interested in sticking that MELF resistors on... Ah well, there's always another amp that I can stick that on. |
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狂人
極資深會員
Joined: 14 Oct 2005
Posts: 1304
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| Posted: Tue Jul 10, 2007 10:40 pm Post subject: |
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| Just remembered that Vishay S102 resistors are also sized to fit the spot on Mini3... I suppose those should work should someone got a fair bit of cash to burn, right? |
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amb
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Joined: 15 Dec 2006
Posts: 45
Location: Sunnyvale, CA, USA
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| Posted: Wed Jul 11, 2007 7:15 am Post subject: |
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| 狂人 wrote: | | Just remembered that Vishay S102 resistors are also sized to fit the spot on Mini3... I suppose those should work should someone got a fair bit of cash to burn, right? |
Yes, they would fit if you form the leads to 5mm pitch. Due to the height of these resistors things could get awfully crowded on the board, next to the L1L and L1R ferrite beads. I don't see why this circuit would need that kind of tight tolerance and temperature stability, though. |
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amb
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Joined: 15 Dec 2006
Posts: 45
Location: Sunnyvale, CA, USA
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| Posted: Wed Jul 11, 2007 3:10 pm Post subject: |
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For your enjoyment... There are more pictures here.
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狂人
極資深會員
Joined: 14 Oct 2005
Posts: 1304
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| Posted: Wed Jul 11, 2007 5:24 pm Post subject: |
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| AMB, honestly speaking, you really should carry those custom panels. No Mini3 should be without it |
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amb
見習員
Joined: 15 Dec 2006
Posts: 45
Location: Sunnyvale, CA, USA
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| Posted: Wed Jul 11, 2007 5:37 pm Post subject: |
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| 狂人 wrote: | | AMB, honestly speaking, you really should carry those custom panels. No Mini3 should be without it |
Yes, they are excellent and make the amp rival commercial products in look-and-feel. However, these panels are expensive for me to stock, so I am running a group-buy on headwize right now. |
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coffin
Topic Manager
Joined: 28 Mar 2005
Posts: 1329
Location: 11F
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| Posted: Wed Jul 11, 2007 11:49 pm Post subject: |
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| amb wrote: | For your enjoyment... There are more pictures here.
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還有還有∼∼
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amb
見習員
Joined: 15 Dec 2006
Posts: 45
Location: Sunnyvale, CA, USA
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| Posted: Fri Jul 27, 2007 1:19 am Post subject: |
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The new Mini³ website is now live. Some sections are still under construction, so please pardon the mess.
Enjoy,
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coffin
Topic Manager
Joined: 28 Mar 2005
Posts: 1329
Location: 11F
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| Posted: Thu Aug 23, 2007 1:26 pm Post subject: |
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恐怖的面板陣列 
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ljvalue
正式會員
Joined: 23 May 2007
Posts: 153
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| Posted: Thu Aug 23, 2007 2:06 pm Post subject: |
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coffin大開的團嗎？
那有沒有機殼的？ |
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