I don't know if you read my posts in the thread, but "there" is a place I'm still trying to work out the location of. I do have time and am prepared for work. I also have good experience of building stereo gear. I do like to ask questions and seek answers to gain understanding. I'm all for clarity. As I wrote, I'm not committed to a JLH design particularly, but something that maximises the potential of the heatsinks that I do own. I'm now planning out an expensive transformer and capacitor purchase that has heavy dependencies on selected topology. I'm trying to understand case formats against power delivery, dissipation and usefulness in one of my domestic systems. I've also requested specific information about some specific boards, that might be suitable for my needs.
Sometimes, I get answers to questions I didn't ask. Sometimes, the answers seem nebulous and mystical, which makes me suspicious - especially if they're brusque and vague. This can lead to new areas of interest of course, or dead ends from misunderstandings, ******* contests and talking at cross-purposes. I find that often, people can be too eager to remain aloof as to their own understandings, rather than tailoring any helpfulness given to the questions asked, or stated requirements of the person asking them. This all makes me further commit to my own reclusiveness and disinterest in social interaction: I realise now it was a mistake to post here, after your earlier "advice" and now your mysterious, egg-based "techno-pile-on", both of which ironically did cause disappointment!
I don't see what's bothering you there.
my metaphor with fried eggs may not work in your country but it was to express that it is easy to make a JLH69 "work" but that it requires a little more work to draw the quintessence from it.
I assembled my first JLH there's maybe 10 or 15 years and since then, a few and yet I have not yet gone around.
I'm not asking you to look for components on Pluto but to pay attention to the selection of these (the fewer components there are, the more important they become).
Now, I was going through this, I read with interest your work and I gave my opinion on what is important or not, but again this is only MY opinion, do what you want with it, it does not concern me and it will not change my life, I am only sharing my experience.
On these words, have a nice day .
[Quote myself]
" in fact, on the jlh69 design (if this is the one we are talking about) only one of the two output transistors "sees" the signal, the other serves as a current amplifier but does not "see" the signal.
Ian directed you to the original article by Mr Hood which clearly explains the importance of work on the "active" components and mainly on the final transistors, there is even a table giving the rate of distortion according to the choice of gain of the power transistors and even depending on whether they are balanced or not.
Mr Hood's original schematic is like fried eggs, extremely simple to make, hard to miss, but extremely hard to turn it into something extraordinary, but when you get there (with work and time) it's is one of the best "daily" that I have known so far, it does not do everything well, but what it does is a real pleasure on a daily basis."
my metaphor with fried eggs may not work in your country but it was to express that it is easy to make a JLH69 "work" but that it requires a little more work to draw the quintessence from it.
I assembled my first JLH there's maybe 10 or 15 years and since then, a few and yet I have not yet gone around.
I'm not asking you to look for components on Pluto but to pay attention to the selection of these (the fewer components there are, the more important they become).
Now, I was going through this, I read with interest your work and I gave my opinion on what is important or not, but again this is only MY opinion, do what you want with it, it does not concern me and it will not change my life, I am only sharing my experience.
On these words, have a nice day .
[Quote myself]
" in fact, on the jlh69 design (if this is the one we are talking about) only one of the two output transistors "sees" the signal, the other serves as a current amplifier but does not "see" the signal.
Ian directed you to the original article by Mr Hood which clearly explains the importance of work on the "active" components and mainly on the final transistors, there is even a table giving the rate of distortion according to the choice of gain of the power transistors and even depending on whether they are balanced or not.
Mr Hood's original schematic is like fried eggs, extremely simple to make, hard to miss, but extremely hard to turn it into something extraordinary, but when you get there (with work and time) it's is one of the best "daily" that I have known so far, it does not do everything well, but what it does is a real pleasure on a daily basis."
I'm sorry that you feel this way about the people who give their time to actually trying to help. Often, problems don't really emerge until questions probe further into the OP level of understanding of electronics and only then can we point to particular information that hopefully, increases knowledge that leads to a successful outcome. People also choose to ignore the wisdom and suggestions of fellow DIYs here for many reasons, some personal, some because the resources are difficult to access or perhaps they find technical matters too intimidating. In any case, we cannot learn more than visual aspects of projects unless we know our starting point and the necessary theory from which to build an understanding.
Frankly, building electronics projects is often disastrous because we don't understand all that is important and why. Maybe we don't realise that it requires more than soldering wires when something goes wrong, either. I've been there too - wasting great effort with little satisfaction. There are no personal issues here that justify being reclusive about your interest though. This is an open forum and some of us are indeed professional engineers, teachers, authors, technicians etc. but plenty of us are just enthusiasts and lurkers - curious DIY folk who just appreciate the project presentations, repair discussions, questions and replies. Best of all, there is awareness, enlightenment and understanding - the precious gems that can be shared by all who are willing to look for them.
I would not expect that every reply here was fully researched and tailored to the wishes of each OP though. This forum is not heavily edited in the Q&A format used by manufacturers to promote their products. You'll need to give replies a little space and consideration for the real people offering them on their own initiative here.
Regarding help with small heatsinks, you might notice the tiny dimensions and spacing of the fins of the type pictured. This suggests that they were intended for use with high velocity, fan forced cooling and it can certainly work if the total rating is equal to or greater than the particular build's rating requires. Unfortunately, it's also likely to be at the cost of dust accumulation and noise , neither of which is worth any savings over the silent, convection cooled types.
Some years ago, when I was assisting a group of "schoolies", I had access to many JLH'69 amps with different build styles, including mini heatsinks of the microprocessor and CPU types. This topic was often argued on a price and availability basis but the evidence of several listening sessions always favoured big "sinks" without any type of fan, since the low output power almost dictates a very quiet room for serious listening.
Some years ago, when I was assisting a group of "schoolies", I had access to many JLH'69 amps with different build styles, including mini heatsinks of the microprocessor and CPU types. This topic was often argued on a price and availability basis but the evidence of several listening sessions always favoured big "sinks" without any type of fan, since the low output power almost dictates a very quiet room for serious listening.
This is the latest version of "JLH2003"
More information you can find on > sound-au.com.
... and on Aliexpress.
It was straight-forward build. Just don't forget to connect collector of Q2A to the point in vicinity of C5 with a wire and be carefull when adjusting quiescent current.
I have built it and works fine. For the time being it waits for a new job as tweeter amplifier in my new two-way system.
Good luck
PS: One of these days I intend to put it again on the bench to perform some measurements and to adapt it to the new duty as a tweeter amplifier. I might also publish some results.
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