Hahaha, I made the plates with a wink to the original 
Ofcourse the amplifier is only assembled in Holland. Actually the amplifier itself is pretty international, got parts from all over the world; cabinet from Italy, trannies from the USA and Malaysia, softstart from China, nuts and bolts from Germany, transformers from Holland and so on.
Ofcourse the amplifier is only assembled in Holland. Actually the amplifier itself is pretty international, got parts from all over the world; cabinet from Italy, trannies from the USA and Malaysia, softstart from China, nuts and bolts from Germany, transformers from Holland and so on.
You are just the humble guy, aren't you?Hahaha, I made the plates with a wink to the original
Ofcourse the amplifier is only assembled in Holland. Actually the amplifier itself is pretty international, got parts from all over the world; cabinet from Italy, trannies from the USA and Malaysia, softstart from China, nuts and bolts from Germany, transformers from Holland and so on.
I am just waiting for Jim's Audio to reply for the third request for the heat sinks for the MJE1502/3s and the speaker protection--Which he says he has at 2 bucks each. I will get the temp sensor, soft-start from the other ebay store you mentioned earlier. I also need to ask an embarrasing question. I know how to figure wattage from a straight transformer, but to use a center tap transformer and applying it to +/- dual rails, how would you figure wattage? For example, I put together a solid state preamp for my ipod. The preamp calls for a 20w trans @ +/- ~12Volts. What kind of amperage am I looking for?
Haha well a sort of spurtle ;-)
Heyheyhey, a question is never embarassing! I for instance aks as many questions as I can, my philosophy is that it will only make you smarter To be fair, I dont really have a centertap, I ve made one instead.
To make a centertap I soldred the yellow and blue wire in series, see the picture below. The connection between yellow and blue is the so called centertap.
Why not solder red and gray in series? Well when you do this you have 0 VAC. This is because the windings have in that case a reversed phase relative to each other, so the sum is 0 VAC. My transformers are rated @ 1000VA (V * A = P in watt). So when you have two windings, you can (in theory) draw 500VA from the first winding (grey and blue) and 500VA from the second winding (yellow and red). For 4 windings it is max 250 VA per winding and so on. The voltage I get per winding is 38,5V. The current I can draw maximally per winding is thus: 500 / 38,5 = 13A per winding @38,5VAC. So that is when I measure current relative to the centertap. When I measure across red and grey I will measure a voltage 2*38,5VAC = 77VAC. The current which I will measure at maximum current across this large winding is 1000 / 77 = 13A.
In your case a 20W transformer is thus 20VA. When you have a centertap you can see the one winding actually as two windings which are connected in series at the centertap. Thus you have (20/2)/12 = 0,83A per winding relative to the centertap. So you can draw at the positive side relative to the centertap 0,83A and at the negative side also 0,83A, but again relative to the centertap.
Offcourse the above is in ideal circumstances. It's a possibility your transformer can handle less than 20VA because you will have losses from the transformer and so on.
Heyheyhey, a question is never embarassing
! I for instance aks as many questions as I can, my philosophy is that it will only make you smarter To be fair, I dont really have a centertap, I ve made one instead. To make a centertap I soldred the yellow and blue wire in series, see the picture below. The connection between yellow and blue is the so called centertap.
Why not solder red and gray in series? Well when you do this you have 0 VAC. This is because the windings have in that case a reversed phase relative to each other, so the sum is 0 VAC. My transformers are rated @ 1000VA (V * A = P in watt). So when you have two windings, you can (in theory) draw 500VA from the first winding (grey and blue) and 500VA from the second winding (yellow and red). For 4 windings it is max 250 VA per winding and so on. The voltage I get per winding is 38,5V. The current I can draw maximally per winding is thus: 500 / 38,5 = 13A per winding @38,5VAC. So that is when I measure current relative to the centertap. When I measure across red and grey I will measure a voltage 2*38,5VAC = 77VAC. The current which I will measure at maximum current across this large winding is 1000 / 77 = 13A.
In your case a 20W transformer is thus 20VA. When you have a centertap you can see the one winding actually as two windings which are connected in series at the centertap. Thus you have (20/2)/12 = 0,83A per winding relative to the centertap. So you can draw at the positive side relative to the centertap 0,83A and at the negative side also 0,83A, but again relative to the centertap.
Offcourse the above is in ideal circumstances. It's a possibility your transformer can handle less than 20VA because you will have losses from the transformer and so on.
It's always the simple things!
Yes, Stuart Easson has told me that we need to do our own studying. I was just about to spend a night playing with a low amperage center tap transformer, but just wanted to get your experience on measuring these transfos. I will studying tonight. I see your colors is a French flag. I visited France 1973 and my daughter-in-law taught english in Paris 5 years ago and is in Paris at the moment. Au revoirHaha well a sort of spurtle ;-)
Heyheyhey, a question is never embarassing
To make a centertap I soldred the yellow and blue wire in series, see the picture below. The connection between yellow and blue is the so called centertap.
Why not solder red and gray in series? Well when you do this you have 0 VAC. This is because the windings have in that case a reversed phase relative to each other, so the sum is 0 VAC. My transformers are rated @ 1000VA (V * A = P in watt). So when you have two windings, you can (in theory) draw 500VA from the first winding (grey and blue) and 500VA from the second winding (yellow and red). For 4 windings it is max 250 VA per winding and so on. The voltage I get per winding is 38,5V. The current I can draw maximally per winding is thus: 500 / 38,5 = 13A per winding @38,5VAC. So that is when I measure current relative to the centertap. When I measure across red and grey I will measure a voltage 2*38,5VAC = 77VAC. The current which I will measure at maximum current across this large winding is 1000 / 77 = 13A.
In your case a 20W transformer is thus 20VA. When you have a centertap you can see the one winding actually as two windings which are connected in series at the centertap. Thus you have (20/2)/12 = 0,83A per winding relative to the centertap. So you can draw at the positive side relative to the centertap 0,83A and at the negative side also 0,83A, but again relative to the centertap.
Offcourse the above is in ideal circumstances. It's a possibility your transformer can handle less than 20VA because you will have losses from the transformer and so on.
Haha, that is right. But the France flag has a subtile difference, it's rotated 90 degrees compared to ours.
The addition which Andrew posted is a good one. When experimenting it is sane to connect a lightbulb (40W or so) in series with your transformer. When you make short circuit your transformer will not burn down, instead the lightbulb will glow very bright, so most current will flow through the lightbulb instead of the short circuit transformer.
By the way I GOT MY PLATES! They turned out realy nice if I may say so Sorry for the a bit arrogant 'designed by...' spurtle, but there was some room left for additional letters haha ;-)
Edit: typoooo
The addition which Andrew posted is a good one. When experimenting it is sane to connect a lightbulb (40W or so) in series with your transformer. When you make short circuit your transformer will not burn down, instead the lightbulb will glow very bright, so most current will flow through the lightbulb instead of the short circuit transformer.
By the way I GOT MY PLATES! They turned out realy nice if I may say so
Sorry for the a bit arrogant 'designed by...' spurtle, but there was some room left for additional letters haha ;-)An externally hosted image should be here but it was not working when we last tested it.
Edit: typoooo
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Well Andrew, the way I recall you, you refuse to explain things to other people when they ask, but maybe that is only to me ;-) But oh my gosh you are right, BAD MICHAEL, there will be a voltage drop due to the light bulb instead.
@ Upupa; Mr. Agostino left Krell :-( What Happened At Krell and Why The D'agostino Family Is Out
Intellectual ownership is a difficult thing. The only thing which really looks like the original Krell design are the logo and the driverboard. But they are not entirely. For example the MJE15030 / MJE15031 are replaced by MJE15032 / MJE15033. I know, little change, but when I add other parts I can say I've made from the schematic a intepretation. It's (a little) different from the original, so there is no legal problem in Holland. In addition there is no patent to the boards, the amplifier itself is my design and I will not sell it commercially. And if it comforts you, I would have never bought a brand new originall Krell anyway so they don't lose clientele ;-) That would also be the case when I bought a second handed KSA-100 (which are not that expensive nowadays), but building one by yourself is just more fun
I think it is almost a honour when people are willing to spend a lot of time and effort to reproduce your obsolete amplifiers because they think they are that good.
@ Upupa; Mr. Agostino left Krell :-( What Happened At Krell and Why The D'agostino Family Is Out
Intellectual ownership is a difficult thing. The only thing which really looks like the original Krell design are the logo and the driverboard. But they are not entirely. For example the MJE15030 / MJE15031 are replaced by MJE15032 / MJE15033. I know, little change, but when I add other parts I can say I've made from the schematic a intepretation. It's (a little) different from the original, so there is no legal problem in Holland. In addition there is no patent to the boards, the amplifier itself is my design and I will not sell it commercially. And if it comforts you, I would have never bought a brand new originall Krell anyway so they don't lose clientele ;-) That would also be the case when I bought a second handed KSA-100 (which are not that expensive nowadays), but building one by yourself is just more fun
I think it is almost a honour when people are willing to spend a lot of time and effort to reproduce your obsolete amplifiers because they think they are that good.
Yes Kaplaars, like I see, laws are elastic all around the world and lawyers are the same slimy snakes everywhere ...but I remember, when one guy was cast out from this forum, because he copied volume control that was originally designed by Mark Levinson company...and why? Only 'cos he was from China and Chinese copy all...I have nothing against you, I understand very well to your precise work and I like it...but I want to say that person should be proud of his work and don't hide behind some famous name...
Hi Upupa,
You are totally right, when people try to gain money just bij copying other peoples hard work that is a very bad thing. But that is absolutely not my intention The amplifier I am constructing right now is almost as a baby to me haha. So chances of selling it are pretty small. Chances of making profit are even smaller. From the other hand, I have to say, banning the Chinese guy just because he is from China is almost equivalent to racism. There woulden't be cheap televisions and so on when China was not there. Labour there is (in my opinion far too) cheap in China. In Holland it is allowed to make a copy from intellectual work under one condition: you absolutely have to keep it for yourself, so in Holland there would be no problem for this guy when he kept it strictly for himself.
The reason why I printed the Krell logo pontifical on the front- and backplates is a hommage to the original Krell, and to be fair, I find the logo realy beautifull. It has nothing to do with hiding against a faimous name. I think the average audiophile, despite of all my efforts, can easily see that it is not an original Krell. And if they dont, they can read it on the front ('KSA 100 DIY PROJECT')
You are totally right, when people try to gain money just bij copying other peoples hard work that is a very bad thing. But that is absolutely not my intention
The amplifier I am constructing right now is almost as a baby to me haha. So chances of selling it are pretty small. Chances of making profit are even smaller. From the other hand, I have to say, banning the Chinese guy just because he is from China is almost equivalent to racism. There woulden't be cheap televisions and so on when China was not there. Labour there is (in my opinion far too) cheap in China. In Holland it is allowed to make a copy from intellectual work under one condition: you absolutely have to keep it for yourself, so in Holland there would be no problem for this guy when he kept it strictly for himself.The reason why I printed the Krell logo pontifical on the front- and backplates is a hommage to the original Krell, and to be fair, I find the logo realy beautifull. It has nothing to do with hiding against a faimous name
. I think the average audiophile, despite of all my efforts, can easily see that it is not an original Krell. And if they dont, they can read it on the front ('KSA 100 DIY PROJECT') As a new member, I read the rules as I really needed positive experiences with the project I wanted to successfully complete. I found that diyaudio had a lot of people that I came to respect. It is sad that some of those turned and lost the respect they have graciously build over trivial matters. It called reversing the "principals over personality." Namely, diyaudio.com's Rule Number 8 -- Discussing topics unrelated to audio or electronics unless in a designated off-topic area. Some, for some reason or another, are using diyaudio.com to advertise (hopefully unknowingly), their personalities over principle. In the words of Rodney King, "Hey, can't we just try to get along?" And get back to the subject at hand. Other new comers who visit diyaudio and see this bickering, will find another forum. I wonder how the moderators passed on these posts?
Hi Spurtle,
It is a shame that I lost your respect. You are right, we have to obey the rules, I am no exception. From the other hand I think we don't have to be more Catholic than the pope when it comes to little off-topic phrases, just like our little chat about France.
To me the discussion about intellectual properties was not bickering, just a friendly discussion. I think Upupa feels the same. I just felt the need to give a explanation why I made the plates are the way they are. I also wanted to explain the legal issues. I use a lot of smileys to express my emotions, but maybe that is not enough and are my answers misinterpret, and is the friendly nature of the posts lost. I honestly want to excuse for that.
My intention was to give a nice overview of building a DIY KSA-100 clone, to learn more about the theory, and to make the amplifier better. So I spended a lot of effort to make nice pictures with a little story around it and try to formulate my questions as good as my knowledge of English allows me.
I am sorried for this off-topic answer. I am even more sorried that my reportage did not turned out so well as I intended. I am not realy a quitter, but I think it is the best draw a close to reporting my build in this topic, so I will. I want to thank everybody for the help they gave me, I've learned a lot
It is a shame that I lost your respect. You are right, we have to obey the rules, I am no exception. From the other hand I think we don't have to be more Catholic than the pope when it comes to little off-topic phrases, just like our little chat about France.
To me the discussion about intellectual properties was not bickering, just a friendly discussion. I think Upupa feels the same. I just felt the need to give a explanation why I made the plates are the way they are. I also wanted to explain the legal issues. I use a lot of smileys to express my emotions, but maybe that is not enough and are my answers misinterpret, and is the friendly nature of the posts lost. I honestly want to excuse for that.
My intention was to give a nice overview of building a DIY KSA-100 clone, to learn more about the theory, and to make the amplifier better. So I spended a lot of effort to make nice pictures with a little story around it and try to formulate my questions as good as my knowledge of English allows me.
I am sorried for this off-topic answer. I am even more sorried that my reportage did not turned out so well as I intended. I am not realy a quitter, but I think it is the best draw a close to reporting my build in this topic, so I will. I want to thank everybody for the help they gave me, I've learned a lot
I'm really sorry how this topic went wrong. Michael, you build an amp for yourself and if you want, you can put NASA stickers on it. It's really up to you. I did something similar like you on my amp and I don't care what someone thinks about it. Don't be angry because of some well-meant but somewhat poignant remarks.
Please, keep us informed and stay cool
Please, keep us informed and stay cool
Mr. Michael
When are we going to hear if the amp is working !!!!
You might just motivate me to finish my KSA 100 watt clone - at least my PCB's have been buildt up for the past 3 years but the lack of having a professional looking case and heatsinks has been a serious drawback as I also want a near professional look.
I have noticed that with my KSA 50 clone that uses heat-tunnels some transistors are warmer than the others. Hence my interest in how your heat/bias management is going to be implemented. With unmatched transistors on a heat-tunnel you possibly need to be more careful with additional heatsinking compared to the commerical units?
Btw I remain impressed with the quality of your workmanship- especially for a 'poor' student you doing very well.
Regards
Jozua
When are we going to hear if the amp is working !!!!
You might just motivate me to finish my KSA 100 watt clone - at least my PCB's have been buildt up for the past 3 years but the lack of having a professional looking case and heatsinks has been a serious drawback as I also want a near professional look.
I have noticed that with my KSA 50 clone that uses heat-tunnels some transistors are warmer than the others. Hence my interest in how your heat/bias management is going to be implemented. With unmatched transistors on a heat-tunnel you possibly need to be more careful with additional heatsinking compared to the commerical units?
Btw I remain impressed with the quality of your workmanship- especially for a 'poor' student you doing very well.
Regards
Jozua
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At the risk at falling into the same trap--Kaplaars, believe me when I say, I was not referring to your endeavors or posts. "Via la France." And you should not be intimidated by anyone else who may have OCD, a control issue, "Do it my way or the highway." Please don't be the quitter!!! We want to see the finished product, "Made in Holland" and more importantly, a finished " DIYAUDIO.COM PROJECT." In your words, ".... in all fairness...."Hi Spurtle,
It is a shame that I lost your respect. You are right, we have to obey the rules, I am no exception. From the other hand I think we don't have to be more Catholic than the pope when it comes to little off-topic phrases, just like our little chat about France.
To me the discussion about intellectual properties was not bickering, just a friendly discussion. I think Upupa feels the same. I just felt the need to give a explanation why I made the plates are the way they are. I also wanted to explain the legal issues. I use a lot of smileys to express my emotions, but maybe that is not enough and are my answers misinterpret, and is the friendly nature of the posts lost. I honestly want to excuse for that.
My intention was to give a nice overview of building a DIY KSA-100 clone, to learn more about the theory, and to make the amplifier better. So I spended a lot of effort to make nice pictures with a little story around it and try to formulate my questions as good as my knowledge of English allows me.
I am sorried for this off-topic answer. I am even more sorried that my reportage did not turned out so well as I intended. I am not realy a quitter, but I think it is the best draw a close to reporting my build in this topic, so I will. I want to thank everybody for the help they gave me, I've learned a lot
Thanks for your support guys! You are right Dean, forgive and forget, fresh new start from here And I want to motivate Jozua, because I want to see more DIY KSA-100's haha.
Well that is going to be a big challenge for me too Jozua, the transistors I use are from the same batch, though I have not matched the transistors specificly. I use 1 ohm emitter resistors so I hope due to the large emitter resistor value bias current will distribute more equally. If this works and heat is distributed equally I want to try 0.47 ohm emitter resistors because I've red this would be better for the sound quality (I do not really understand why this would improve quality, maybe someone can explain?). If heat becomes a real issue I think I have to bias less. Hope I don't have to, but from the other hand it is maybe not a very big problem. I never listen to music very loud, so at worst case scenario even 25W of power would be more than enough. When I am right voltage across the emitter resistors for 4 ohm loudspeakers than have to be P=I^2*R --> 25 = x^2*4 so x = 2.5 Arms, thus 2.5 / 0.707 = 3.54--> 3.54 / 8 (=output devices) = .442. So I have to measure 442 mV across the 1 ohm emitter resistors. By the way, this raises another question, I've red the original has about 625 mv across the 1 ohm emitter resistors. This would mean the KSA-100 is only full biassed at 8 ohm. At 4 ohm bias has to be 884 mV when it is full biassed because: 100 = x^2*4 so x = 5 Arms, thus 5 / 0.707 = 7.072--> 7.072 / 8 = .884 mV, or am I wrong?
By the way, I ordered a few days ago a push button. It has a nice ring around the button itself which is lit white by a led. Drilling the hole into the front plate was a real hurdle to me. Although the front plate is made from aluminium, it is still 10 mm thick. But actually it was more easy than I thought. When drilling through aluminum you have to drill really slow. It is almost like when you think you are drilling too slow, you have the right speed. I also added some WD40 to lubricate the drill a bit. Worked like a charm. I also mounted the front and backplates. Some pictures:
And the back plate. Like you can see I have just enough room to mount the speaker terminals
And I want to motivate Jozua, because I want to see more DIY KSA-100's haha.Well that is going to be a big challenge for me too Jozua, the transistors I use are from the same batch, though I have not matched the transistors specificly. I use 1 ohm emitter resistors so I hope due to the large emitter resistor value bias current will distribute more equally. If this works and heat is distributed equally I want to try 0.47 ohm emitter resistors because I've red this would be better for the sound quality (I do not really understand why this would improve quality, maybe someone can explain?). If heat becomes a real issue I think I have to bias less. Hope I don't have to, but from the other hand it is maybe not a very big problem. I never listen to music very loud, so at worst case scenario even 25W of power would be more than enough. When I am right voltage across the emitter resistors for 4 ohm loudspeakers than have to be P=I^2*R --> 25 = x^2*4 so x = 2.5 Arms, thus 2.5 / 0.707 = 3.54--> 3.54 / 8 (=output devices) = .442. So I have to measure 442 mV across the 1 ohm emitter resistors. By the way, this raises another question, I've red the original has about 625 mv across the 1 ohm emitter resistors. This would mean the KSA-100 is only full biassed at 8 ohm. At 4 ohm bias has to be 884 mV when it is full biassed because: 100 = x^2*4 so x = 5 Arms, thus 5 / 0.707 = 7.072--> 7.072 / 8 = .884 mV, or am I wrong?
By the way, I ordered a few days ago a push button. It has a nice ring around the button itself which is lit white by a led. Drilling the hole into the front plate was a real hurdle to me. Although the front plate is made from aluminium, it is still 10 mm thick. But actually it was more easy than I thought. When drilling through aluminum you have to drill really slow. It is almost like when you think you are drilling too slow, you have the right speed. I also added some WD40 to lubricate the drill a bit. Worked like a charm. I also mounted the front and backplates. Some pictures:
An externally hosted image should be here but it was not working when we last tested it.
And the back plate. Like you can see I have just enough room to mount the speaker terminals
An externally hosted image should be here but it was not working when we last tested it.
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I used .47 ohm emitters on mine and from the same batch. The mv spread across all TO3,s was less than 15mv so no problems with current hogging as far as I,m concerned. Simply measure each output transistors emitter and write down the value and compare them. If one is way off just replace it and remeasure to get the total average down.
Changing to .47 ohm results in a change in output impedance and a resultant bias change remember
A lower bias had no detrimental effect that I could detect sonically
It did take a good 60 hours or so of running in before the sound fully came into its own and settled down to its smooth and detailed sweet self. Happened within about 2 or 3 songs and was a shocker on how this developed so quickly. Can,t explain why this should be, but has stayed that way ever since.
Burn in is real so don,t expect great sound at first start up!
Regards
David
Changing to .47 ohm results in a change in output impedance and a resultant bias change remember
A lower bias had no detrimental effect that I could detect sonically
It did take a good 60 hours or so of running in before the sound fully came into its own and settled down to its smooth and detailed sweet self. Happened within about 2 or 3 songs and was a shocker on how this developed so quickly. Can,t explain why this should be, but has stayed that way ever since.
Burn in is real so don,t expect great sound at first start up!
Regards
David
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