hi i have been building a ksa 50 and having some troubles with the power supply i am using 500va 50 0 50 toroidal transformer with 470000uf 63v capactitor iv been using a diagram found on google images but i keep getting 140v across across the plus and minus rails would anyone have a better idea i am a little stumped.😱
wrong transformer
the ksa50 uses ~25-0-25Vac transformer.
The ksa100, which is massive, uses a 37-0-37Vac transformer.
50-0-50Vac transformer is for big PA work, except they have moved over to smps to save weight and heat.
the ksa50 uses ~25-0-25Vac transformer.
The ksa100, which is massive, uses a 37-0-37Vac transformer.
50-0-50Vac transformer is for big PA work, except they have moved over to smps to save weight and heat.
hey guys i really want to build this krellclone
but resuming all the thread can someone post the final parts list and pcbs for iron method
thanks in advance
but resuming all the thread can someone post the final parts list and pcbs for iron method
thanks in advance
guys im planning on using a 40 0 40 transformer, i simulated the circuit on multism i can share it for everyone, assorting to the simulation the VI outputs increases THD and keeping them away and increasing the voltage to 50VDC gives me 67w and a extreme low THD
whats your expirience?
regards wolfintosh
whats your expirience?
regards wolfintosh
The KSA50 clone described in this thread uses 37-0-37 DC rails. Heat dissipation requires immense passive heat sinks or sinks that are fan cooled with all the issues of fan noise.
I constructed this amplifier but used 25-0-25 DC rails, dissipating about 70watts per channel in heat,this gave an amp that had a reasonable physical size with passive cooling, although still quite a heavy lump to move.
Very pleased with the result.
Bear in mind what is continually said about Class A ---- never underestimate the amount of cooling required.
Alan
I constructed this amplifier but used 25-0-25 DC rails, dissipating about 70watts per channel in heat,this gave an amp that had a reasonable physical size with passive cooling, although still quite a heavy lump to move.
Very pleased with the result.
Bear in mind what is continually said about Class A ---- never underestimate the amount of cooling required.
Alan
the KSA100 used a 37Vac dual secondary.
The KSA50 came in at least 2 versions, one as far as I remember used a higher voltage transformer than the normal KSA50. Both had a lower voltage than the KSA100.
a dual 25Vac transformer would make a good KSA50 clone.
a dual 30Vac transformer will make a hot KSA50 clone.
a dual 35Vac transformer will probably blow up a KSA50 clone.
No body thinks about using a dual 40Vac for any KSA50 clone.
The KSA50 came in at least 2 versions, one as far as I remember used a higher voltage transformer than the normal KSA50. Both had a lower voltage than the KSA100.
a dual 25Vac transformer would make a good KSA50 clone.
a dual 30Vac transformer will make a hot KSA50 clone.
a dual 35Vac transformer will probably blow up a KSA50 clone.
No body thinks about using a dual 40Vac for any KSA50 clone.
guys heeeeeeellpppppp needed, i built my clone today was working beautifully with 30vdc but i played a 20 hz frequency and a 100 ohm resistor burned, i replaced it and no luck it drains .4 amps on the negative side heats the same resistor till it burns again
You have a very serious problem or mistake somewhere. Double check everything and remove semi's from the board and test them all. Also test output devices. 30 volt rails is a reasonable DC voltage on this amplifier and shouldn't cause any headaches. When you get it working again use a variable to slowly bring it up and also a scope to be sure the amplifier is not self oscillating. KSA-50 is an extremely simple, stable reliable circuit. Mine is now 9 years old...
Thanks Mark, ill check it again i tested with multimeter an seems that one of the masa transistor is the one that got broken, im thinking about oscilation because it failed after i played a 20hz reference tone, with music worked for hours
Wolfintosh, I presume you mean one of the 100ohm emitter resistors for the pre-driver transistors ? What was the total bias per rail you were using with 30V rails ? What circuit are you using-- the Delta Audio from the start of this thread ? What load were you driving into ?
Alan
Alan
thats correct, the bias pot i have it adjusted almost halfway at normal bias a 5k pot, im using the delta audio version , my goal its to run it with 42v rails it is been tested with my lab power supply, i replaced the masa transistors and some 2240 and 970 the ones that are placed almost together and it worked again, i want to tweet it and prevent this, also i made measurments with the scope at school an the signal look perfect without load, it an 8 ohm load with that i get a bit of distortion on politeve cycles of the sinusoidal wave produced by the function generator
If someone is looking for a nice done KSA50 mkII -->>http://www.diyaudio.com/forums/swap-meet/278907-krell-ksa-50-mkii-eu-only.html
Attachments
hey guys i solved the issue of my previous posts, now i attemped to build the second channel, and im having a sound at the output like if it was pink noise, i checked the board and everything seems just like tho one that its working any ideas?
regard wolfintosh
regard wolfintosh
pcb
i've some pcb for delta audio clone on baia :
kit pcb amplificatore krell-ksa50 clone amplifier class A | eBay
thanks
i've some pcb for delta audio clone on baia :
kit pcb amplificatore krell-ksa50 clone amplifier class A | eBay
thanks
guys keep building this but i have one working channel, the others worked and they failed after a while, i replaced the small transistors and no luck any thoughts?
hey guys having a huge doubt, I've been looking for a transformer in my country has been a headache, currently I've been testing it with my lab power supply which gives me +-32VDC but i own a transformer from an old sony amp 100WPC supposedly I've measure it and gives me 60VDC rectified could i use this DC voyage with Jan Dupont PCB????
or i should regulate the voltage to 42v my heatsinks are massive 4 inch tall 16 long per transistor row 2 heatsinks and i will add temp control
or i should regulate the voltage to 42v my heatsinks are massive 4 inch tall 16 long per transistor row 2 heatsinks and i will add temp control
I am posting this here as well as in the for sale threads...
Have been going through old parts and stuff this past week and ran across a few 2nd Generation boards I had made way back when this long running thread switched boards. These boards were made way back when the prototype boards were made except I had them gold plated with black stencil laytou for the parts. They look very sharp. I also had a dozen KSA-100 boards done the same way but I only have two of those left now and am going to hold on to them.
I have five (5) sets of the boards shown in the attached pictures if anyone is interested. I am not giving them away, I need to get $40 USD per set for them. I likely paid more than that for them when the prototypes were originally made because I only had 16 boards made and only a Dozen were gold plated.
When these are gone that's the last of my KSA-50 stuff from when this thread began.
Mark
https://www.flickr.com/photos/56008415@N03/22241088783/in/dateposted-public/
Have been going through old parts and stuff this past week and ran across a few 2nd Generation boards I had made way back when this long running thread switched boards. These boards were made way back when the prototype boards were made except I had them gold plated with black stencil laytou for the parts. They look very sharp. I also had a dozen KSA-100 boards done the same way but I only have two of those left now and am going to hold on to them.
I have five (5) sets of the boards shown in the attached pictures if anyone is interested. I am not giving them away, I need to get $40 USD per set for them. I likely paid more than that for them when the prototypes were originally made because I only had 16 boards made and only a Dozen were gold plated.
When these are gone that's the last of my KSA-50 stuff from when this thread began.
Mark
An externally hosted image should be here but it was not working when we last tested it.
https://www.flickr.com/photos/56008415@N03/22241088783/in/dateposted-public/
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