John Lindsey Hood [JLH] amp offer

[Hiten]

guys,
here is very comprehensive information about heatsinks.
ESP - Heatsink design and transistor mounting
read heatsink surface area topic. As it has calculations of 10w amp also there is downloadable heatsink calculator.
Regards

 

[captrajesh]

Captain,

Air or desert coolers (or thermantidotes as they were earlier called) work very effectively in the hot, dry summers of North India, cooling the rooms by evaporation of water trickling down panels of wood shavings through which air is sucked inside the rooms by fans.

They lose their efficiency once the monsoons set in and the air becomes too humid for cooling by evaporation to remain effective.

The are however more environmentally friendly than air conditioners which transfer heat from inside the rooms to outside.

If the equipment is placed closed to windows or other openings it should be possible to suck in air at ambient temperatures from outside the room and to expel the heated air using ducts? Too Heath Robinsonish for your liking?

Regards.

Hi Miroflex,

Sorry for the late reply; I somehow missed your post.

Desert Coolers are ineffective in coastal places like Chennai where humidity levels are always on higher side. Facilitating cross ventilation using multiple exhaust fans is doable but would need considerable work of placing exhaust fans at both sides of the listening room and making them work in sync with the wind direction. On that account, it does sound "Heath Robinsonish"

Regards


Rajesh

 

[anilva]

The heat has to go somewhere. From the amp into the surroundings. I wonder by how many degrees the temperature in the room housing the amp would go up to. But then there are too many variables there.

Too man comments on room ambient temperature going up. My personal experience (which is quite a bit on this matter) normal room size does not go up by even 1 degree centigrade without any special ventilation and air flow. Looks like people have a mistaken impression that it burns red hot. Please remember that the total power consumption of a F5 is around 250-300W. How much heat can it totally generate assuming Class A efficiency. Definitely not enough to push room temperature by couple of degrees.

 

[keith_correa]

My personal experience (which is quite a bit on this matter) normal room size does not go up by even 1 degree centigrade without any special ventilation and air flow.

I'm sure you meant room temperature If room size had to go up with Class A amps, given the real estate prices in Mumbai, I would be building Class A amps just for the increased space they would induce.

Jokes apart - a 1 deg. increase is not too bad at all. Thanks!

 

[captrajesh]

My personal experience (which is quite a bit on this matter) normal room size (perhaps you meant temperature?) does not go up by even 1 degree centigrade without any special ventilation and air flow. Looks like people have a mistaken impression that it burns red hot. Please remember that the total power consumption of a F5 is around 250-300W. How much heat can it totally generate assuming Class A efficiency. Definitely not enough to push room temperature by couple of degrees.

Hmm, yes you do have a point there. There were many posts previously, notably from our erstwhile forum member Cranky with whom I interacted who have indicated so and hence the mistaken notion. Thank you for clarifying but alas, it is a trifle late. I had already purchased a commercial Pre and power combo and not inclined to invest anymore in the near future. May be, I can take up building a BOSOZ pre and F5 Power amp few years down the line.

 

[anilva]

I'm sure you meant room temperature If room size had to go up with Class A amps, given the real estate prices in Mumbai, I would be building Class A amps just for the increased space they would induce.

Jokes apart - a 1 deg. increase is not too bad at all. Thanks!

Unfortunately there are no such easy means to increase our living spaces Thanks for pointing out the typo. I meant temperature in normal room sizes...

 

[anilva]

Hmm, yes you do have a point there. There were many posts previously, notably from our erstwhile forum member Cranky with whom I interacted who have indicated so and hence the mistaken notion. Thank you for clarifying but alas, it is a trifle late. I had already purchased a commercial Pre and power combo and not inclined to invest anymore in the near future. May be, I can take up building a BOSOZ pre and F5 Power amp few years down the line.

I agree. There is a tendency to make these builds sound so complex and esoteric that normal DIYers move away from it. My idea to let DIYers know that projects like F5 can be attempted by anyone, with necessary attention paid to power supply, heat-sinking and setup. The build can be simple one going all the way up to an extremely over-engineered one.

 

[GeorgeO]

Anilva has built a few elegant Pass amps and it was, for me at least, an eye opener. I have not ruled out diying an F5 of my own at a future date.

 

[miroflex]

Hi Miroflex,

...Desert Coolers are ineffective in coastal places like Chennai where humidity levels are always on higher side. ...

Regards.

Rajesh

Hi Capt Rajesh,

I agree with you. That is why I had specifically mentioned the hot, dry summers of North India in my post.

By the way, I don't agree with the view that 300 watts would lead to a negligible rise in room temperature. Most room heaters used in North India during the winters are of 1000 watts and are quite effective in raising room temperatures to comfortable levels in average sized rooms.

Regards.

 

[quad]

By the way, I don't agree with the view that 300 watts would lead to a negligible rise in room temperature. Most room heaters used in North India during the winters are of 1000 watts and are quite effective in raising room temperatures to comfortable levels in average sized rooms.

In an amp, the energy goes into the audio output, and any
heat generated is a side effect of the losses as there no "ideal" devices.
Hopefully, a 300W amp is not generating 300W heat.

 

[miroflex]

In an amp, the energy goes into the audio output, and any
heat generated is a side effect of the losses as there no "ideal" devices.
Hopefully, a 300W amp is not generating 300W heat.

I agree, Quad.

The point is that the amp may be drawing much more than its rated capacity and dissipating the surplus energy as heat.

Regards.

 

[keith_correa]

Check this

 

[keith_correa]

Free power supply pcb for JLH class A amplifier.
Including all capacitors and resistors.
Transistors are not included.

 

[La Mer]

You are right captain. Here is 10w JLH from La mer of DIYaudio.

WOW find my this photo by google :yahoo:

I also have 2 verions of 3W JLH1969 too as following picture :yahoo: