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PostPosted: 23 Dec 2010, 15:35 
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Joined: 06 Jun 2008, 18:23
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Location: Australia
Small heatsinks back-2-back works for me.

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 Post subject: Re: Headphone Buffer
PostPosted: 08 Jan 2011, 11:12 
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Joined: 07 Aug 2010, 06:24
Posts: 44
Location: India
I took care in isolating with rubber pads as well as thermal compound but something like this happened,

CCS resistor overheated ---> LM317 ! thermal shutdown (saved) ----> IRF630's Thermal shutdown failed :( !


P.S i have a 25 Watt cheapo soldering iron it doesn't solder that well, i have to hold for a long period of time, till that the protoboard burns :@ what am i doing wrong?

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 Post subject: Re: Headphone Buffer
PostPosted: 08 Jan 2011, 12:47 
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Joined: 24 Jun 2010, 00:48
Posts: 788
Location: Christchurch, NZ
3 possibilities :

1. Tip is worn out
2. Soldering iron is too low in power. 40-60 watt is ideal
3. Wrong type of solder used. Silver solder can be difficult to solder.

Most of my soldering is done with a cheap 60W iron, and I hold the soldering iron for no longer than 1 second to solder each hole.

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PostPosted: 08 Jan 2011, 14:00 
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Joined: 28 May 2008, 21:53
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Location: Winnipeg, CANADA
Rohan wrote:
CCS resistor overheated ---> LM317 ! thermal shutdown (saved) ----> IRF630's Thermal shutdown failed

An IRF630 is typically used for switching power supplies and would not have sounded good as there will have been a terrible roll-off of the highs. An IRF510, IRF610, IRF611 or IRF612 are all good choices for the class-A biased buffer circuit.

The resistor to set the CCS needs to be at least 1/2W and I elevated mine from the board so it gets good air-flow around it. What size of resistor did you use?

Rohan wrote:
P.S i have a 25 Watt cheapo soldering iron it doesn't solder that well, i have to hold for a long period of time, till that the protoboard burns :@ what am i doing wrong?

You could be over heating the parts and damaging them. The tips Dinesh suggested are all good. You should not need that large of an iron, A 35W Weller has been fine for me.

One thing I do with semiconductors is use a small aluminum clip heat sink when soldering them.

For the soldering, Rosin core 60/40 solder is the easiest to work with.

Cheers

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PostPosted: 08 Jan 2011, 22:53 
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Joined: 24 Jun 2010, 00:48
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Location: Christchurch, NZ
Gio wrote:
One thing I do with semiconductors is use a small aluminum clip heat sink when soldering them.

Hi Gio that is really good too. I use a standard alligator clip and attach it to each lead of a transistor/FET above the board before soldering. Works well and it does draw heat away quite efficiently.


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PostPosted: 09 Jan 2011, 00:02 
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Location: India
So, these are for $ 50 i got mine for 2$ :P no wonder, they don't work

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PostPosted: 13 May 2011, 21:56 
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Joined: 19 Jun 2010, 17:08
Posts: 71
Hi,

how does this HPA sound compared to a Class A Zen HPA?

they should sound very similiar? definatley the Zen has lots of gain.


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PostPosted: 15 Sep 2011, 21:32 
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Joined: 15 Sep 2011, 18:29
Posts: 1
I built one of these amps and the problem im having is that it has no amplificaton at all. infact the volume is lower coming out of the amp than it is stright from my mp3. player my supply voltage is 18 volts. i did use IRF510's insted of IRF610's I was told that the IRF510's would work too. the sound is good with no noticeable distortion. I just wondered if the volume was low because of the IRF510's was used I did make sure that the offset was set to half the drain voltage. any help will be greatly appericated...


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PostPosted: 18 Sep 2011, 19:12 
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Joined: 28 May 2008, 21:53
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Location: Winnipeg, CANADA
Hi Keith, the gain of the amp is about 0.8 - noted in the first post and also in the project page. IRF510 are good too. It sounds like it works fine. The NP-100v12: 12AU7 (ECC82) tube / IRF510 MOSFET Headphone Amplifier has the same output stage but a tube in front for more gain.

Cheers

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PostPosted: 29 Apr 2012, 09:38 
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Joined: 15 Aug 2011, 08:01
Posts: 9
hello everyone please pardon my english.
I have built this amp using the irf510 and my lm317 has a 2.2ohm resistor across its adjust and output. works well so far with my wall wart . however I am building a dedicated power supply thus I am wondering if I should wire my 12V center tapped transformer to produce 17vdc or 34vdc ? it is rated at 1 amp by the way. I plan to have about40000uf of filtering and will regulate it with a lm317 if it hums. I won't really be using it for headphones but rather I
am planning to hopefully use it to power the tweeters of my klipsch rb61. will I be possible to bias the amp for more than half my supply voltage? as I have found the sound to be better with a higher bias. thank you in advance :D Quartz


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