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sergiu2009
diyAudio Member

Join Date: Apr 2011
Location: romania

Good evening dear colleagues,
As i am starting to collect parts for this wonderful amp i found myself in a dilemma. I have bought these two radiators from the picture attached and hoping to find some answers from you guys:
*Note that the dimensions for both of them are: L=25.5 cm; l=23.5cm; h (for the base)=1 cm. The dimensions for the fins are: L= 23.5cm and h=2.5 cm. The black radiator has one fin less than the other.
1. Are these results ok for the total dissipation area?
Abase=2(L*h+l*h+L*l) =>Abase is 648.25 square cm + 885 square cm for the total of 15 fins (from the formula Atot=L*l*Number of fins) => A=23.5*2.5*15?
The total dissipation area is, from the calculation above (for the black radiator) 1533 square cm?
2. Are these radiators suited for a stereo JLH for QUAD ESL at 42W@8Ohm , 3.2A quiescent current with 4 pieces 2n3055 per module?
3. Wich solution is best for the silver radiator: to spray it with a black thin coat of thermo resistant paint or to black anodise it (sollution wich i do not have at disposal in my county)?
Attached Images

 3rd July 2013, 06:14 PM #2 sergiu2009   diyAudio Member     Join Date: Apr 2011 Location: romania The voltage for the amp wil be +- 28V CC. Thanks.
 3rd July 2013, 06:22 PM #3 sergiu2009   diyAudio Member     Join Date: Apr 2011 Location: romania I am thinking at ataching an aluminium L pad (with the output transistors) on the 1 cm base of the radiators and make a case with the radiators standing up. What do you say?
 3rd July 2013, 06:35 PM #4 generg   diyAudio Member     Join Date: Jul 2009 Location: Near Frankfurt Sergiu2009 I am afraid you are more competent in these things than me..... If nobody answers here, hijack the Pass Forum open a thread, I suppose you will get help! Good luck! __________________ and the First Wtt is......a really First Class PSS Idea
 3rd July 2013, 06:39 PM #5 sergiu2009   diyAudio Member     Join Date: Apr 2011 Location: romania Thanks generg. I have send allot of mp's to allot of colleagues that can help and i am hoping that they can help me and post here.
sergiu2009
diyAudio Member

Join Date: Apr 2011
Location: romania
This is the schematic that i want to use on these radiators.
Attached Images
 jlhupdatefig3.gif (9.5 KB, 124 views)

 4th July 2013, 11:09 AM #8 geraldfryjr   diyAudio Member   Join Date: Feb 2008 Location: Jackson,michigan On painting the heatsink, You want to keep the paint layer as thin as you can. The object is to cover the material but not have a thick build up of paint. If it is rough and sandy feeling this is good as this has a rougher surface and has the effect of increasing the surface area. jer
 4th July 2013, 11:42 AM #9 AKSA   diyAudio Member   Join Date: Sep 2001 Location: Melbourne, Australia Sergiu, I have heard that the JLH is not particularly good with an ESL; it has some instability at higher loads of capacitance due to phase shift. The heatsinks are OK, but you really need to measure the thermal capacity and the quiescent current of the output current of each amp. Until we know the rating in C/W we cannot know how much the rise of temp. The best topologies with highly reactive loads like ESLs are Class A tubes. Cheers, Hugh __________________ Aspen Amplifiers P/L (Australia) www.aksaonline.com
 4th July 2013, 12:29 PM #10 geraldfryjr   diyAudio Member   Join Date: Feb 2008 Location: Jackson,michigan This is something I wish to explore. The JLH is a simple Class A amp of yesteryear. And when working with ESL's you must understand how the impedance curve works and how it effects the voltage output of the amplifier. Most amps don't handle this very well but a Class A amp can do this very well with in its designed range of operation. If the signal is out of phase by 90 degrees whether it be lag or lead due to the reactive components it requires the amp to maintiain nearly 5 to 6 times the current or voltage depending on lag or lead of the reactive component, to maintain the same power level. This is why it takes a big amp that can deliver a large amounts of current to make the speakers produce what they have to produce to make the sound right. But, When it comes to a purely capacitive load the extra current is a plus. Since the current is leading, the amplifier has to supply larger amount of current at once. This is only for the highest of frequency's. This does not include the effect of the transformer except for its added (or Parasitic capacitance). At the lower frequency's the transformer's inductance of the primary winding is what determine's the impedance that is presented to the amplifiers output and has no effect on the ability for the ESL to produce sound except for its surface area, as for all bass system's! The ESL at this point has a very high impedance and the the voltage the it presented upon its stator's is what determines what position the diaphragm will be at. I have full DC control over my ESL Diaphragms. At a low frequency a capacitor has its highest impedance and it takes nearly zero current to make the diaphragm move. To make bass you must have Displacement! The Higher the frequency of operation you need more current, It works like this in the RF world too!! jer Last edited by geraldfryjr; 4th July 2013 at 12:42 PM.

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