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Class A Headphone Amplifier with IRF610 and LM317 CCS
http://diyaudioprojects.com/Forum/viewtopic.php?f=10&t=55
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Author:  Rohan [ 13 Dec 2010, 06:32 ]
Post subject:  Re: Class A Headphone Amplifier with IRF610 and LM317 CCS

hi guys finally made the layout of the circuit :mrgreen: please check it out and tell me if there are some faults or if you have time can someone please give me a layout as i am quite new to DIY and this will probably my first project thanks

rohan
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Author:  Vy74u745 [ 13 Dec 2010, 07:25 ]
Post subject:  Re: Class A Headphone Amplifier with IRF610 and LM317 CCS

Just made this "Amplifier" which unAmplifies sound :(
Distorted guitar sound become plastic when run through the amp.
To end with I would like to state that if you want a good radiator for winter you should definitely build this amp because IRF610 and LM317 gets really hot

P.S. How you can call this thing an amplifier when gain is lower than 1.

Author:  Gio [ 13 Dec 2010, 11:44 ]
Post subject:  Re: Class A Headphone Amplifier with IRF610 and LM317 CCS

Vy74u745 wrote:
P.S. How you can call this thing an amplifier when gain is lower than 1.

I agree, the generic term "amplifier" is typically assumed to mean a gain >1.

From the wikipedia:
http://en.wikipedia.org/wiki/Amplifier wrote:
Generally, an amplifier or simply amp, is any device that changes, usually increases, the amplitude of a signal.

A good example in audio is the "power amplifier" which usually has a gain of <1.

A more descriptive title would be - headphone driver, buffer or headphone power amplifier. I'll update the pages to a more descriptive title. However, please note that the first post in this thread the gain of 0.8 was noted and it is also noted twice in the project page. I try make the page titles as descriptive as possible, but I would suggest that potential project builders read the project text to see if the project will suit their needs.

Thanks for the feedback.

Author:  Gio [ 13 Dec 2010, 12:01 ]
Post subject:  Re: Class A Headphone Amplifier with IRF610 and LM317 CCS

Rohan wrote:
hi guys finally made the layout of the circuit please check it out and tell me if there are some faults

Hi Rohan. That is a good start. It is always good to plan out a project. About the potentiometer you used - a audio taper attenuator. This potentiometer is used to set the bias, not to attenuate the signal. I would suggest that you use a linear multi-turn trimmer pot like I used. It is way smaller and should cost less.

Cheers

Author:  KrammeAcoustics [ 13 Dec 2010, 12:05 ]
Post subject:  Re: Class A Headphone Amplifier with IRF610 and LM317 CCS

This Buffer amplifier Wiki link, is good reading ( hope it becomes helpful ). :snowman: :xmass: :present:

Author:  mwhouston [ 13 Dec 2010, 17:01 ]
Post subject:  Re: Class A Headphone Amplifier with IRF610 and LM317 CCS

Gio wrote:
Vy74u745 wrote:
P.S. How you can call this thing an amplifier when gain is lower than 1.

I agree, the generic term "amplifier" is typically assumed to mean a gain >1.

From the wikipedia:
http://en.wikipedia.org/wiki/Amplifier wrote:
Generally, an amplifier or simply amp, is any device that changes, usually increases, the amplitude of a signal.

A good example in audio is the "power amplifier" which usually has a gain of <1.

A more descriptive title would be - headphone driver, buffer or headphone power amplifier. I'll update the pages to a more descriptive title. However, please note that the first post in this thread the gain <1 (0.8) was noted (I just made it bold) and it is also noted twice in the project page. I try make the page titles as descriptive as possible, but I would suggest that potential project builders read the project text to see if the project will suit their needs.

Thanks for the feedback.

This is the same as my 2N3055 (Woody series) headphone drivers.

Author:  faileas [ 22 Dec 2010, 01:10 ]
Post subject:  Re: Class A Headphone Amplifier with IRF610 and LM317 CCS

Right. I'm just about ready to start soldering- a few small things still bother me - Firstly i'm using a small heatsink designed to be mounted on a T220 package - the thermal pads have no holes - so do i punch holes in them, or did i get the wrong sort? Also, is the heatsink i'm using suitable? Secondly, if they arn't, can i test the set up with no heatsink for VERY short periods of time?
Image
this is what i have on hand - i've bolted on the heatsink loosely to test fit the parts - I'll be getting proper mount kits at some point.

Author:  dtsup1 [ 22 Dec 2010, 02:19 ]
Post subject:  Re: Class A Headphone Amplifier with IRF610 and LM317 CCS

Hi,

You don't need a thermal pad. Just mount it directly to the heatsink. However, make sure that the heatsink does not come into contact with any metal parts surrounding it. Use a thin layer of thermal grease to ensure better heat transfer.

I have some BD139/140's mounted directly to the heatsink below. (in another preamp project)

EDIT : The heatsink is way too small. Take a look at the pics on the first page.
In that case, it's better to use a large heatsink and insulating pads.
If you fix the chip directly to a large heatsink, you cannot ground it, so the heatsink may act as an antenna for interference to get in.

Author:  dtsup1 [ 22 Dec 2010, 03:13 ]
Post subject:  Re: Class A Headphone Amplifier with IRF610 and LM317 CCS

faileas wrote:
... can i test the set up with no heatsink for VERY short periods of time?.

No. Not recommended. You can use the TO-220 heatsink for a very quick 10 second test =P

Author:  Gio [ 23 Dec 2010, 13:37 ]
Post subject:  Re: Class A Headphone Amplifier with IRF610 and LM317 CCS

The thermal pad is really insulation to isolate the metal tab from the heatsink. As long as you don't ground the heatsink to the circuit ground, isolation is not required so you can skip the pad.

That is likely too small of a heatsink. However, if you have a bunch of those you could turn two heatsinks back to back which would double the heatsink size. However, that will likely only be enough for testing.

Cheers

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