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Thread: Sound Valves stereo 70 amplifier help

  1. #11
    VIP/Donor [VIP/Donor] microstrip's Avatar
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    Quote Originally Posted by Mastercaster View Post
    Thank you for your help. I cut the resistor out of R9 and I did OK with it. The information on the resistor reads Tepro TS 3W 15.4 1%NI 6550. Could one of you actually Tell me what I should order and where I might get them from? I would like to replace R8, R9, R22, R23, R42 and R43. I think I have some new tubes for another project. I'm uncertain of the brand and uncertain where they are. Can you suggest a tube brand? What is the wattage of Resistor you are suggesting as a 100K ohm? 1 Watt? What should I put in R8 and R9? I understand I should install a 1 watt, but what value should I use? What type of resistor do I order? I just want to get something ordered so I can get it back up and running. Thank you again.
    From where are you getting the resistors? The brand is not critical, although I would select some metal film, between .4 to 1 watt for the grids. If you can not get the 15.6 easily you can associate two resistors to get this value. The output tubes should be close matched, as you can only monitor the sum of the cathode currents.
    Under construction around a pair of Wilson XLF's and a DCS Vivaldi 2.0 stack : conrad Johnson GAT, Lamm M1.2, TA OPUS MM2 +TA XL digital, TA XL gen V power cables ...

  2. #12
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    I shopped Ebay for a quad matched set of Electro Harmonix EL34's. They were $16.00 each. I purchased a matched pair of 6GH8A tubes for $6.00. I purchased 5 each 15 OHM resistors that are 1 watt 5% for R8 and R9. Will these work? I purchased 100K OHM 1 watt resistors for 22, 23, 42, and 43. They were $2.69 for 5 each with free postage. Are Carbon film a bad choice? I do appreciate your help. Once I have the parts in hand the repair should be easy enough. If I can successfully build a Van Alstine Preamp kit, I should be able to do this. I purchased 10 ohm and 5.6 ohm 1watt metal film resistors. How do I best install them? the top one or the bottom one. Thank you Name:  resistor install 1.jpg
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    Last edited by Mastercaster; 09-04-2017 at 07:35 PM.

  3. #13
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    I installed 15.6 ohm 1watt carbon resistors in 8 and 9 along with the new tubes. Sounds as good as new. Thanks for the help.

  4. #14
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    Quote Originally Posted by Mastercaster View Post
    I installed 15.6 ohm 1watt carbon resistors in 8 and 9 along with the new tubes. Sounds as good as new. Thanks for the help.
    Sorry, I missed your previous post. Happy to know you managed to repair the amplifier. Surely you selected the top (series) association!

    Although carbon is considered a noisier resistor some audiophiles prefer them in tube equipment.It is not easy to have a firm answer on this point. The critical point is perhaps the quality of the resistor, not exactly the type.
    Under construction around a pair of Wilson XLF's and a DCS Vivaldi 2.0 stack : conrad Johnson GAT, Lamm M1.2, TA OPUS MM2 +TA XL digital, TA XL gen V power cables ...

  5. #15
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    I asked the question but realized my meter would tell me upon trying the test. I installed a single resistor instead. As above I purchased 100K metal film 1watt resistors for the other four spots. Do you think this will help balance the bias? The adjustable resistor no longer seems to work as intended and the high bias is the only one that will light up. Any suggestions? Thank you for your help.

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