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jack

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  1. jack

    krell ksa5 klone

    Hi AlSp I built KG's device as a pre. There is not much information in this thread about how this amp. reproduces sound. IMHO there is no need to use a thicker layer of copper, bearing in mind that you will be using a maximum of 30 Watts. I believe we could use better capacitors and resistors. Cheers
  2. jack

    krell ksa5 klone

    True! If it sounds good does not necessarily mean it will taste good ;-) Since good is subjective what does good mean to you in audio gear? in what area doen an opamp has to excel in order to be qualified as good?
  3. jack

    krell ksa5 klone

    Is it sarcasm or sth. I do not understand? Sent from my iPad using Tapatalk
  4. jack

    krell ksa5 klone

    I am still testing. Yesterday my burson v5i s opamp arrived, they still need to run for a dozen of hours for the final test, however as of now I can tell that they bring much more improvement in my DAC (DIY based on ESS9028) than in my preamp (that is the the KSA5). The idea of "upgrading" the opamps in the KSA5 came after i received counterfeit OP27 from ebay: the sound was terrible with lots of noise. Once i replaced them with Analog Devices original OP27G from Mouser, the KSA5 started to sound great, and then with BurrBrown's OPA445 even better IMHO, as i find it sounding natural. I also think about replacing my nichcons KA with KG, not sure what it will change, or if it will change anything though. Building, replacing, testing is an activity i really enjoy, that relaxes me a lot after a hard day at work. I should have chosen electronics instead of economics for my studies ;-) my lack of knowledge is a serious limiter for me, but you gentlemen and a great support and help. thank you!
  5. jack

    krell ksa5 klone

    Pars. PSU is running @ 23.2 V DC. Transformer is 27.5 V AC. I no not mean opamps in the PSU. as i already know that they either work or or not work. I think you told me that previously ;-) so i changed the op27 to the cheaper op07 and the psu seems fine. I have heard Operational amplifier have their own sound charecteristics or signature, therefore looking if changing OPAMPS in the amplifier will "improve" or change anything. I have testes the op27 and OPA 445 i find the forst one less precise with to much lows.
  6. jack

    krell ksa5 klone

    Hi Did any of you try to play with the opamps? I am tempted to do an upgrade of the opa445. Please let me know your thoughts. Thanks
  7. jack

    krell ksa5 klone

    Hi I tried to test the amplifier in class AB, but the lowest voltage i get is 89 mv (hot). did anyone mange to get it to work at lower voltage?
  8. jack

    krell ksa5 klone

    Thank you. I understand across as measuring voltage between 2 leads of the same R. I have a problem though one channel is significantly louder.... any idea where to start investigation?
  9. jack

    krell ksa5 klone

    Thank you, i can see, 125mV cold 100 mV warm. In another post i read that the test points are between any of the 2 ohm resistor. is that correct?
  10. jack

    krell ksa5 klone

    I am done with the boards. now wornikng on the case, and some setup. Could you please help me with the bias? what are the optimal values, and what are the measeure points? Many thanks
  11. jack

    krell ksa5 klone

    Could someone please confirm that a dual 28V 50W toroidal transformer with the alternate psu version (to-3) will be ok to use the amp a a line preamp?
  12. jack

    krell ksa5 klone

    Thank you for explaining. I have read this thread several times, nevertheless it happens to me to ask silly questions as I know less than a little about electronics ;-)Am I correct ?The best would be to have a transformer maid with a voltage between 27 and 28 V so that DC right after the rectifier (bridge) is 35 V. I think this can be done since my toroids are custom made. I have also read in this thread that some pushed PSU voltage higher and changed opamps. Could someone tell me if this is worth it? What are the benefits? I can still return my ops. So why not benefit from a good advise. Sent from my iPad using Tapatalk
  13. jack

    krell ksa5 klone

    I will be using the power supply as in the picture bellow (the PCB arrived today ) So happy Sent from my iPad using Tapatalk
  14. jack

    krell ksa5 klone

    Trendsetter want to charge me like hell for shipping. Found some on ebay. hope they are not fake ;-) I am looking for a transformer, I read in this forum, that 2x27V 50VA should be used. my question is 27 V with or without load. Is my understanding correct that the board will draw less than 400mA (0.4 A x 21 V= 8.4 VA)so should not make a difference for a 50VA transformer?
  15. jack

    krell ksa5 klone

    Do you think i can use 2N5564 instead of LSK389?
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