John Lindsey Hood [JLH] amp offer

[keith_correa]

There are free boards given out here for the venerable JLH Class A amplifier.

These are not free though:

A kit for this here.

And a PS with speaker protection onboard too.​

Nice. I'm tempted. You?

 

[Hiten]

Thanks for the link Keith. Looks good but it says PCB is not tested. was wondering if we can DIY JLH amp (tested and revised) here how much will it cost ?
Regards

 

[quad]

Thanks for the link Keith. Looks good but it says PCB is not tested. was wondering if we can DIY JLH amp (tested and revised) here how much will it cost ?
Regards

That PCB does not look "khas". I think it may be worthwhile persuading
Omishra to have a go designing one for this circuit
The component cost should be just a few hundred rupees.

 

[Hiten]

Thanks quad. Have been following LME49830 (posted by you in HFV) and class AB amp on DIYaudio. LME49830 also looks good having few components for technically chalanged people like me. Waiting for listening impression of both the amps.
Regarding JLH, what would very approx. cost would be for (PS+AMP) PCB+components+trans.
Regards

 

[keith_correa]

that pcb does not look "khas". I think it may be worthwhile persuading omishra to have a go designing one for this circuit

+100...............................

 

[captrajesh]

what would very approx. cost would be for (PS+AMP) PCB+components+trans.

You are forgetting heatsinks. Remember, it is class A amp

 

[Hiten]

Thanks Captain,
as this must be low power (around 10W) amp Heatsink I guess can be salvaged from an old amp. But not sure.
Regards

 

[captrajesh]

Thanks Captain,
as this must be low power (around 10W) amp Heatsink I guess can be salvaged from an old amp. But not sure.
Regards

Hiten bhai, do not underestimate Class A. Whether it is a pint sized cheetah or King sized lion, cat is always a cat.hyeah:

 

[Hiten]

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

 

[captrajesh]

There you go. This (the heat) is the only reason I had abandoned my plans of building an PassDIY F5. Not suitable for a tropical country like India, at least not Chennai or Hyderabad.:sad:

 

[anilva]

There you go. This (the heat) is the only reason I had abandoned my plans of building an PassDIY F5. Not suitable for a tropical country like India, at least not Chennai or Hyderabad.:sad:

Captain,

Don't abandon plans on such assumptions. Pass F5 can happily work in Hyderabad or Chennai or Cal for that matter. All you need to give it, is a good piece of heatsink. The transistors used there can withstand junction temps close to 120 deg. With heatsinks, you can operate them at 50-70 deg. You can improvise by adding small fans to the heatsinks. The cooling efficiency improves dramatically.

I have a F5 with a ultra low noise fan. It is compact and runs cool.

 

[borg]

:^
good to hear that. i am going to build one for my apartment in china.The weather is quite close to what we have here except in winters(even if captain is right i could use the f5 as a heater in winter).Still waiting for the "large" heatsink promised by one of our vendors. i am getting it free
got the components and pcb from diyaudio store

 

[keith_correa]

It is compact and runs cool.

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.

 

[miroflex]

Thanks Captain,
as this must be low power (around 10W) amp Heatsink I guess can be salvaged from an old amp. But not sure.
Regards

Hi,

Has anyone tried casting custom made heat sinks, using hand made patterns? It should prove an easy and economical source, particularly if a number of DIYers share the cost of pattern making. Any thoughts, anyone?

Regards.

 

[captrajesh]

Captain,

Don't abandon plans on such assumptions. Pass F5 can happily work in Hyderabad or Chennai or Cal for that matter. All you need to give it, is a good piece of heatsink. The transistors used there can withstand junction temps close to 120 deg. With heatsinks, you can operate them at 50-70 deg. You can improvise by adding small fans to the heatsinks. The cooling efficiency improves dramatically.

even if captain is right i could use the f5 as a heater in winter

I do understand the heat dissipation from the amp to the atmosphere can be achieved effectively by using heat sinks and fans irrespective of the ambient temperatures. I was referring to this:

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.

It's effect on room temperature would be substantial IMO if we do not have air conditioning during summers.

 

[Hiten]

Miro,
good suggestion but different amp and enclosures need different sizes of heat sink, so that would be a problem.

 

[miroflex]

Miro,
good suggestion but different amp and enclosures need different sizes of heat sink, so that would be a problem.

Hiten,

I agree, but there are many group buy/build projects in the DIY forum where my suggestion may address a need felt and expressed by many by providing the required number of heat sinks of the requisite size and capacity for the given number of DIY projects for the group as a whole. It is also possible to use a number of smaller units where larger heat sink capacity is required, using a suitable cabinet design and arranging the sink units as per requirement.
I am sorry if my sentences have become rather complex but I hope I have been able to convey what I mean.

Regards.

 

[miroflex]

I do understand the heat dissipation from the amp to the atmosphere can be achieved effectively by using heat sinks and fans irrespective of the ambient temperatures. I was referring to this:...
It's effect on room temperature would be substantial IMO if we do not have air conditioning during summers.

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.

 

[quad]

Hi,

Has anyone tried casting custom made heat sinks, using hand made patterns? It should prove an easy and economical source, particularly if a number of DIYers share the cost of pattern making. Any thought, anyone?

Regards.

It is doable. The pattern can be made with pink styrofoam,
and cast using the Lost Foam process. However, it may need
a good bit of buffing for finishing it. And probably anodising as well.
See the link below -

Lost Foam Metal Casting

Foam Mould

 

[Hiten]

Hiten,

I agree, but there are many group buy/build projects in the DIY forum where my suggestion may address a need felt and expressed by many by providing the required number of heat sinks of the requisite size and capacity for the given number of DIY projects for the group as a whole. It is also possible to use a number of smaller units where larger heat sink capacity is required, using a suitable cabinet design and arranging the sink units as per requirement.
I am sorry if my sentences have become rather complex but I hope I have been able to convey what I mean.

Regards.

Hey bro dont be sorry. I appreciate your suggestion and pointed out the difficulties only to work out a solution.
Regards