Tandbergen,
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Br Walter
you can buy 25x Elko radial 220uF 200V 10000h @ 105°C RM5 12,5x40mm ; RoHS ; EKXJ201ELL221MK
here 25x Elko radial 220uF 200V 10000h @ 105°C RM5 12,5x40mm ; RoHS ; EKXJ201ELL221MK | eBay
Br Walter
Thanks a lot.
Theese will do the trick., I think.
Quite crowded this PCB. And then the capacitors are in house(nearly)
Just now I am about to match the MPSA42/92 transistors and wait until my cabinewt arrives from Italy. All looking extremely good so far.
Progress is extremely slow here.
Good for me I am not doing this for a living.
But the most components are in place, now I am only waiting for my cabinet to arrive.
Done some math on the heatsinks and discover that I need to help them a little bit.
Too much power, too small heatsink. A beginners error it should have been, but to obtain the best possible WAF I couldn't get the enclosure needed to avoid forced cooling.
Damned.
Good for me I am not doing this for a living.
But the most components are in place, now I am only waiting for my cabinet to arrive.
Done some math on the heatsinks and discover that I need to help them a little bit.
Too much power, too small heatsink. A beginners error it should have been, but to obtain the best possible WAF I couldn't get the enclosure needed to avoid forced cooling.
Damned.
I am going for a heatsink of 500X180X60.
Hope it will be suficient.
I also will change the transformer from 2X625VA to 2X1250VA.
Probably by just adding 2X625VA extra.
Otherwise I will not get more than 258W in 8 Ohms.
I must have been sleeping when determining the transformers.
The GM9 is a monoblock opposed to to what I in a weak moment I thougt it to be a stereoamp. Explaining the mishappen with the size on the transformers.
Should really have been at 1500VA+ each channel.
Hope it will be suficient.
I also will change the transformer from 2X625VA to 2X1250VA.
Probably by just adding 2X625VA extra.
Otherwise I will not get more than 258W in 8 Ohms.
I must have been sleeping when determining the transformers.
The GM9 is a monoblock opposed to to what I in a weak moment I thougt it to be a stereoamp. Explaining the mishappen with the size on the transformers.
Should really have been at 1500VA+ each channel.
Hahaha yeah I'm surprised too to see the "upgrade" scheme
The LTP current source is not a mystery to me, but the voltage doubler/regulator is. I don't understand the reason for such a simple approach. I guess custom transformer is expensive?? But it is an expensive amp!
I agree that the voltagedoubler is a bit "over the hill". A sollution with some more windings on the transformer would be just as fine, and the transformer was Goldmunds own anyway, wasn't it? Probable Goldmund wanted to make the supply very independable of the load but still there is not very much room for regulation there. Not too stable either. Would possibly been easier and better with some adjustments to the custom transformer used.
By the way, what is the problem with a PSU wich is able to provide some extra current when demanded from the amp? Seems as if it is an issue for both You and jacco.
My miscalculation to the powertransformer is easily corrected, still I am a bit embarrased over making such an basic error.
By the way, what is the problem with a PSU wich is able to provide some extra current when demanded from the amp? Seems as if it is an issue for both You and jacco.
My miscalculation to the powertransformer is easily corrected, still I am a bit embarrased over making such an basic error.
3 pairs of J55/K176 makes 750W max dissipation.
Figure out the answer yourself.
(hint : Perreaux 5150, or take another good look at your Tandberg 3016A schematic))
Yes, I am aware of the POSSIBLE problem.
But since this project was made with a somewhat limited PCB, I will have to deal with excactly that problem when my new transformers arrive.
Luckily the heatsink is capable of dealing with it, and then a 6 pair transistor output might take care of the "missing".
Right now there is a possible 258W output available, making the maximum dissipation just around 350W. Should do fine for the transistors.
Whenever I increase the transformers size I will end up with a good 350W output in 8 Ohm, and a dissipation power of around 800W. Probable the figures will be slightly better. There is some losses I haven't calculated just yet. But there is room for it, don't you think?
My real concern is the drivertransistors in this amp.
I probably will give up some speed to achieve decent drive of the output transistors, as I am a little dazzled that theese two was used by Goldmund afterall. Probably the sollution is to give them some better cooling than what has been indicated through this build, but if You have built this amp I am sure you are aware of it.
There is quite a list of issues with the PCB I rather would have pointed at IF I had entered the build at an earlier stage. Too much space has been taken for a cirquit wich with a great advantage could have been made on a separate board. I am not sure why the decition was made to have the speaker protection onboard. Also the space around the VAS and drivers should have been taken better care of. Aswell as the prestage powersupply.
All in all I think this build will be one for me to alter completely, including new PCB.
And by all means, Alex has done a good job, fast and relatively good layout, but I see the discussion was far more over less significant issues than actually making the board as good as it could have been.
The rtesponsibility for this I place upon the more experienced DIYers in here.
Some of them (you?) should have alerted Alex about such things.
And did you ever have doubt to the fact that the 3016 has 4 pairs?
This build will be to grow as the final testresults is on the paper.
Are we good?
By the way.
After having looked at the "origin" for this project, it seems as if Goldmund never calculated with 750W dissipated power for this amp. Go figure.
Heavy and VERY powerful Its at 400W / 8 Ohms? Or even more?
800W/ 4 Ohms, stiff as a nail.
Meaning ?
(Goldmund sized the power supply so that it didn't have to, was the correct answer. The 3016A had 8x125=1000W max dissipation available for 220W/8, plus dissipation aids)
And you missed the alterations I have planned?
After having gone through the flaws in the design of this project?
And where have I said anything about NOT having some dissipation aids?
Will 12X125W do the trick for You?
I am having quite hard time here sorting out what lies behind Your attacks on me here. Is there anything I have written that made You uncomfortable in any way?
Goldmund sized their powersupply so they didn't have to?
Tell me how they both are able to get out 350W in 8 Ohm aswell as "designing their powersupply so they didn't have to" (take care of the dissipation?)
Do some simple math with the supply they actually made and tell me where the watts came from and where it went.
I could place a 15KVA transformer in this amplifier without having to deal with another watt dissipation in the output transistors given the simple fact that I will have an amplifier as stiff as any Goldmund original.
Looking forward to see some numbers about the Goldmund dissipation allowing the very small heatsink. And please tell me what power the transformer delivers to the amp, and what power to go out from the Goldmind Mimesis 9.2