hi everyone, how important is it that non inductive resistors are used for the output transistor emitters. Does anyone know where to get them from in the UK without it costing a fortune, the only type I have seen are thick film and they are about £3 each
Thanks, Alan
Thanks, Alan
I don't recall any requirement for low inductance output emitter resistors. I've got metal clad dales which probably have some inductance, works fine.
hi.I want to learn about krell ksa50's capacitors.. I saw 63volts 15000uf nippon kmh capacitors for 2,5dollars in a store.I thought paralleling them.But i always see big capacitors on projects.they are very expensive.I have some questions.
1)Which capacitor is more suitable for krell? paralleling little capacitors or using only two huge capacitors ?
2)Which brand capacitor is good for money to use in krell ksa50?
thank you very much
1)Which capacitor is more suitable for krell? paralleling little capacitors or using only two huge capacitors ?
2)Which brand capacitor is good for money to use in krell ksa50?
thank you very much
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Hello
I think that in orginal Krell capacitor is 40000uF
People say that is better 2X20000 rader that 40000uF but i dont yet build Krell clone and i dont know ( in Krell )
I have 4 x 33000 for the krell and a add 10000 for each capacitor ( 43000uf ) but my trafo is 2X32 400VA ( +/- 45V ) and i scare that this voltage is to much
I think that in orginal Krell capacitor is 40000uF
People say that is better 2X20000 rader that 40000uF but i dont yet build Krell clone and i dont know ( in Krell )
I have 4 x 33000 for the krell and a add 10000 for each capacitor ( 43000uf ) but my trafo is 2X32 400VA ( +/- 45V ) and i scare that this voltage is to much
some schematics and theory on power supplies for solid state amps in general: Solid State Power Amplifier Supply Part 1
and here is in-depth article on capacitors: Capacitor Characteristics
and here is in-depth article on capacitors: Capacitor Characteristics
Hi.I have 600va transformer and it makes +-50 volt DC . this transformer is not powerful enough. Is it possible to build a class AB krell circuit? I think i will use 8 transistors per channel and 250ma bias per transistors. How much class A and how much class ab power can i get ? thank you
a 4pair ClassAB with Re=0r1 and transistor bias set to Vre~20mVre will give a total output bias of ~0.8A.
The ClassA output will be ~1.6Apk, about 10W into 8r0
The 600VA and 4pair with +-40mF/channel should give about 200W into 4r0
The ClassA output will be ~1.6Apk, about 10W into 8r0
The 600VA and 4pair with +-40mF/channel should give about 200W into 4r0
Hi,
check the voltage rating of all the passive and active components.
Find out what the maximum DC voltage from your transformer is when on near zero loading and mains is at supplier's maximum tolerance.
Have you asked your electricity supplier what the tolerance is on your mains supply?
check the voltage rating of all the passive and active components.
Find out what the maximum DC voltage from your transformer is when on near zero loading and mains is at supplier's maximum tolerance.
Have you asked your electricity supplier what the tolerance is on your mains supply?
No I asked about any modification on the krell circuit. I have 600va 4x18 v ac toroidal transformer.I will connect in series and have 2x36 volts ac and use 6 pieces of nichicon kmh 63 volts 15000uf capacitors for getting +-50volts dc. Do you think there will be a problem? can i get only 10watts class a ? I will use 4ohms nokia german 185mm speakers.
No, the ClassA output is current defined. 4pair biased to 200mA each will give a maximum of 1.6Apk of ClassA current.
what happens if i use +-25volts dc and double the bias?does krell work at this voltage? can i get more class a power ?
It's about time you learned how and why amplifiers work before setting out to design one for your self.
yes i think i learned something.If i use 4ohm speakers i can not get enough class a power with 800ma bias at+-50 volts..and maybe there will be a modification on the krell circuit to run at+-25 volts to run low impedance speakers to get more class a power
I am in the process of building a Krell KSA 50. On the circuit boards I have obtained the value for C105 and C106 are 22pf, this also applies to the circuit diagram.
On all the other diagrams this value is higher at 390pf for C105 and C106. Which is correct? Does any body know?.
On all the other diagrams this value is higher at 390pf for C105 and C106. Which is correct? Does any body know?.
I've built with 39pF as original has, and works fine. 390 pF is mistake. Don't go significantly below 39pF because oscilations may occur, 22pF is too low. Some of the guys here build with 47pF and this is also ok 😉
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Sorry, those have been gone for a couple years. The Gerber files may be in someone's possession if you want to go that route. 6 pairs of KSA50 boards remain.
Bob G.
Update
I was checking settings on my amp before taking higher rail voltage (36 VDC loaded to 48 VDC loaded) and I've find some interesting things. Emitter resistors bias was only 298 mV / 0,5 ohm (drop from initial setting cca 320 mV) on warm amp (45 deg after 3 hours). So, I've raised bias to 340 mV (50 deg afer 3 hours) and...wonderful, deep and strong bass emerge. There was no need for offset adjustment becouse it was 0 mV and steady. I think that is the similar result with lower rail voltage / higher bias and higher rail voltage / lower bias (mk1 had 36,5 V rails and 1,9 A bias, mk2 had 48 V rails and only 1A bias). Statemants from Terry, pinkmouse, Jozua, PWatts, kvholio and my experience bring me to this conclusion.
Regards
I was checking settings on my amp before taking higher rail voltage (36 VDC loaded to 48 VDC loaded) and I've find some interesting things. Emitter resistors bias was only 298 mV / 0,5 ohm (drop from initial setting cca 320 mV) on warm amp (45 deg after 3 hours). So, I've raised bias to 340 mV (50 deg afer 3 hours) and...wonderful, deep and strong bass emerge. There was no need for offset adjustment becouse it was 0 mV and steady. I think that is the similar result with lower rail voltage / higher bias and higher rail voltage / lower bias (mk1 had 36,5 V rails and 1,9 A bias, mk2 had 48 V rails and only 1A bias). Statemants from Terry, pinkmouse, Jozua, PWatts, kvholio and my experience bring me to this conclusion.
Regards