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Thread: ampeg svt 4 pro

  1. #1
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    ampeg svt 4 pro

    Hello good afternoon
    Can someone please tell me a way to regulate the Bias ap101 and ap201

    Channel A distorts
    Last edited by alansombr; 07-09-2017 at 07:14 PM.

  2. #2
    "Thermionic Apocalypse" -JT nickb's Avatar
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    I'm really not sure what you are asking. I'm guessing English is not your native language so try writing in your own language as well as English and see if that helps.

    It sounds like you have an SVT-4 Pro on which channel A is distorting. Try feeding the channel A preamp output to another amplifier to see how is sounds. That will at least tell us if the problem is in the preamp or the power amp.

    Do you have much experience of electronics? What test equipment do you have?
    Experience is something you get, just after you really needed it.

  3. #3
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    Quote Originally Posted by nickb View Post
    I'm really not sure what you are asking. I'm guessing English is not your native language so try writing in your own language as well as English and see if that helps.

    It sounds like you have an SVT-4 Pro on which channel A is distorting. Try feeding the channel A preamp output to another amplifier to see how is sounds. That will at least tell us if the problem is in the preamp or the power amp.

    Do you have much experience of electronics? What test equipment do you have?


    Ok nickb, thanks

    Yes, I did this test.
    And the power, I think the bias is not regulated correctly
    I changed the bias of 500R by 470R, because here in Brazil I find only 470r
    I've been messing around for a while, but ampeg always takes a sura, I have a minipa

  4. #4
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    I take the pre test to a friend on your ampeg svt 4 and the test was very well done and the pre works perfectly,
    Can you tell me how to regulate the ap101 bias?
    Can you tell me if they are mirrored ap101 and ap 201? Or each has an individual geogulation

  5. #5
    "Thermionic Apocalypse" -JT nickb's Avatar
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    Look at sheet 2. The bias setting instructions are on the center right.

    Ampeg_SVT-4_PRO_Power_Amp_(07S428)_Schematics.pdf

    If the bias is too high it will overheat, too low and you will get some distortion.
    Have looked at the output waveform?
    Have you tested the FETS?
    Experience is something you get, just after you really needed it.

  6. #6
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    Quote Originally Posted by nickb View Post
    Look at sheet 2. The bias setting instructions are on the center right.

    Ampeg_SVT-4_PRO_Power_Amp_(07S428)_Schematics.pdf

    If the bias is too high it will overheat, too low and you will get some distortion.
    Have looked at the output waveform?
    Have you tested the FETS?
    Ok thanks a lot
    FETS are new
    I'll regulate at 25mv (I'll try with my digital multimeter)
    And I'll tell you again
    My hp is burned, my son I call 220 and I have not looked at it yet
    Thanks and sorry for the inconvenience and Good weekend

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    Quote Originally Posted by alansombr View Post
    Ok thanks a lot
    FETS are new
    I'll regulate at 25mv (I'll try with my digital multimeter)
    And I'll tell you again
    My hp is burned, my son I call 220 and I have not looked at it yet
    Thanks and sorry for the inconvenience and Good weekend

    I'm calling in a 150W bulb to regulate, okay to use a parallel bulb to regulate or I have to call

  8. #8
    "Thermionic Apocalypse" -JT nickb's Avatar
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    I'm not much of a believer in using a light bulb limiter for solid state amps. The transistors will blow faster than the the bulb heats up. I prefer to use a variac and monitor the current. If you have no other choice then 150W is too big. 40W is more like it.
    Experience is something you get, just after you really needed it.

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    Quote Originally Posted by nickb View Post
    I'm not much of a believer in using a light bulb limiter for solid state amps. The transistors will blow faster than the the bulb heats up. I prefer to use a variac and monitor the current. If you have no other choice then 150W is too big. 40W is more like it.

    ok

  10. #10
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    Quote Originally Posted by nickb View Post
    I'm not much of a believer in using a light bulb limiter for solid state amps. The transistors will blow faster than the the bulb heats up. I prefer to use a variac and monitor the current. If you have no other choice then 150W is too big. 40W is more like it.
    I think I have a 60 watt, okay?

  11. #11
    "Thermionic Apocalypse" -JT nickb's Avatar
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    Quote Originally Posted by alansombr View Post
    I think I have a 60 watt, okay?
    That would be OK.
    Experience is something you get, just after you really needed it.

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