Forum Top Banner Ad

Collapse

Ebay Classic organs

Collapse

Announcement

Collapse
No announcement yet.

Leslie 122 low treble => crossover problem?

Collapse
This topic is closed.
X
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Leslie 122 low treble => crossover problem?

    Hi,

    I think my Leslie 122 is missing some high frequencies. E.g. I Can't hear leakage at all...and I hear a lot of leakage and higher frequencies when I use another speaker (leslie clone) (I know that V21's are not as bright as other horn drivers). Can wrong capacitor values be the reason? From what I know, too high capacitance in the highpass filter would reduce the cutoff frequencies and let more bass reach the horn driver. But then the high frequencies should still be there....? Is it possible to bypass the crossover network to see if more high frequencies are present or would I damage the horn driver?

    I have already switched the horn driver, it does not seem to be the reason.

    Greetings Christian
    1958 B3, 1960 M3, 1953 M2 converted into M3, 2x Leslie 122, Ventilator II, Viscount Legend Solo

  • #2
    In addition to drifting in value, the crossover capacitors increase in ESR (Equivalent Series Resistance) over time, which means that more amplifier power is dissipated inside the capacitor. You have to have relatively specialized equipment to test for this. Modern polypropylene capacitors have lower losses.

    Have you narrowed it down by eliminating the 122 amplifier as the problem? They were designed to roll off some high end, probably to voice them like Hammond Tone Cabinets, which are notable for being somewhat rolled off in the higher frequencies.
    I'm David. 'Dave' is someone else's name.

    Comment


    • #3
      Originally posted by David Anderson View Post
      Have you narrowed it down by eliminating the 122 amplifier as the problem? They were designed to roll off some high end, probably to voice them like Hammond Tone Cabinets, which are notable for being somewhat rolled off in the higher frequencies.
      But wouldn't that mean every 122 amp should show this characteristic?

      And what about bypassing the crossover network? ....just to get an opinion if it cuts out higher frequencies.....possible...? or no good idea?
      1958 B3, 1960 M3, 1953 M2 converted into M3, 2x Leslie 122, Ventilator II, Viscount Legend Solo

      Comment


      • #4
        Originally posted by geldo79 View Post
        But wouldn't that mean every 122 amp should show this characteristic?

        And what about bypassing the crossover network? ....just to get an opinion if it cuts out higher frequencies.....possible...? or no good idea?
        Yes, every 122 amp has some degree of treble rolloff, but I don't know if your 122 has anything wrong with it or not. I'm just trying to be conceptually thorough.

        And, yes, you can bypass the crossover to test the V21. I test them with a SS bench amp and a sine wave generator. Just don't go too low.
        I'm David. 'Dave' is someone else's name.

        Comment


        • #5
          Originally posted by David Anderson View Post
          Yes, every 122 amp has some degree of treble rolloff, but I don't know if your 122 has anything wrong with it or not.
          Okay, I will check that too. You mean the 390k resistors and .0047muF capacitors near the 6550 tubes?
          1958 B3, 1960 M3, 1953 M2 converted into M3, 2x Leslie 122, Ventilator II, Viscount Legend Solo

          Comment


          • #6
            Originally posted by geldo79 View Post
            Okay, I will check that too. You mean the 390k resistors and .0047muF capacitors near the 6550 tubes?
            No, if you do the R/C calculations on those, they provide negative feedback for the output tubes for amplifier stability.

            What I was attempting to emphasize was that in cases of frequency response problems, you want to verify that every link in the chain is working properly.
            I'm David. 'Dave' is someone else's name.

            Comment

            Working...
            X