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Sessionette 75 ILP 'brick'

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  • #31
    Thanks a lot.
    VERY interesting heatsink shape.
    I am designing a brick but using flat aluminum plate, 2.5 to 3 mm thick ... ... far easier to get

    As of your technique: yes, epoxy becomes brittle with heat.
    I do the same, but with a narrow stream heat gun and a dental pick to crack it out, bit by bit, and forcefully "disassemble" speakers, think high power JBL, EV and such, for which there is no way to get original cones here in Argentina, so I have to reuse them.
    Also a rotary file, either conical or ball, mounted on a Dremel.

    Your boards cracked inevitable because any temperature which affects potting epoxy will also affect PCB base material.
    Doubly so those paper phenolic ones, but even glass-epoxy ones will be much weakened, by definition.

    I was surprised at the amplifier complexity, I expected much simpler ones.

    Of course these used plain bipolars and not expensive Mos Fets and they had to add good short protection so they last long beyond warranty period.
    Juan Manuel Fahey

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    • #32
      Hello guys, I need some help with my sessionette 75, that stopped working during a concert some time ago..

      I assume the problem is in the power amp as mentioned above, because I can hear the sound from the effects loop. The problem is that the original power amp was replaced by a previous owner (probably for malfunction) for some DIY board made of old Tesla components.. I think it added little character to the amp but no one wants to repair it cause there is no schematic for the circuit...

      So Im thinking about getting some new power amp for my beloved Session..

      I would like to ask you what do you think about these modules I found online and whether you would use them in this situation..

      https://www.ebay.co.uk/itm/ASSEMBLED...-/253545982141

      Or

      https://www.ebay.com/itm/DIY-Power-a...fQA-uTBLDftsbg

      Also I measured about +-55V across the rails, which seems little bit too high.. Is it ok for both power amps??

      Thank you for your help..

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      • #33
        Sadly none of these.
        The top one does not even have matching schematic and PCB, go figure.
        Maybe they thought "hey, those buying ready made amps canīt read schematics" or something similar.

        The second one wonīt stand those high voltage rails.

        Since EBay always exaggerates specs, I suggest you search for so called "150/180W" amps, so they will hopefully be able to stand that supply and deliver real 100W

        Read supply specs, you expect someone saying "supply up to +/- 60V ... recommended +/-55V" or thereabouts.

        Problem is also that it must fit in the limited space available and use the aluminum back panel as heat sink.
        Juan Manuel Fahey

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        • #34
          Originally posted by J M Fahey View Post
          Sadly none of these.
          The top one does not even have matching schematic and PCB, go figure.
          Maybe they thought "hey, those buying ready made amps canīt read schematics" or something similar.

          The second one wonīt stand those high voltage rails.

          Since EBay always exaggerates specs, I suggest you search for so called "150/180W" amps, so they will hopefully be able to stand that supply and deliver real 100W

          Read supply specs, you expect someone saying "supply up to +/- 60V ... recommended +/-55V" or thereabouts.

          Problem is also that it must fit in the limited space available and use the aluminum back panel as heat sink.
          Thank you for your quick reply I m going to keep looking for the right module.

          Is there also some recommended Input sensitivity for the power module? Is for example 860mV enough to cope with some distortion ? Thanks

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          • #35
            Old ILP bricks were sold as "use anywhere" power modules, so sensitivity must have bewen between 500mV and 1 V ... and Sessionette preamp was designed to work with that.

            My point being that most "normal" power amps will work there.

            As mentioned above, the main specs to meet are:

            * stand +/-55V ... because thatīs the unloaded "raw" supply voltage, thatīs why I now suggest you search for a 150/180W amplifier ... since they use such voltage rails.

            "100W" ones use around +/-40V rails (again, Raw unloaded voltage) , a few +/- 42 to 45V ones ... sadly not enough.

            * fit in the available space.
            Juan Manuel Fahey

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