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    Turn Leslie off during breaks?

    I have a 145 I'll be using at gigs and i was wondering the best strategy during breaks. Guitar players use standby but obviously thats not an option. Is it better/easier on the tubes to leave it on with the rotors on slow or should it be shut off for 15-20 minute breaks? I always heard that startup was tough on tubes but you gotta balance that with the heat stress on summer days when it is 90+ degrees. Also, does the amp run cooler with the lower back panel off? Or is heat not an issue with a 147 amp thats cranked?

    #2
    There's an awful lot of moving parts in that question.

    I doubt there's any hard data supporting much of any conclusion except for the fairly obvious. Motors that spin wear more than motors that aren't spinning. Moving belts wear more than stationary belts. But the amps? Pure speculation on everyone's part. They'll last for a very long time. Many have been left on for days and WEEKS at a time in churches and skating rinks where they've been accidentally left powered up. No problem.

    Well, unless there already was a problem.

    An amp that's running old caps, unbiased tubes, and slightly-leaking transformers can hardly be used as a data point, but many, if not most, gigging 145s are exactly that. So if your amp is in top nick; your belts are fresh and supple; and your motors and bearings are properly lubed and aligned, then you can't gig enough to hurt the thing. You'll give out before it does.

    But if you're not sure about your internals, then sure, you might have to baby things. Reach over and unplug motors and stuff.

    Take the amp to a good valve tech. Get it re-capped and closely checked. Freshen it up like new. Do this every other year. Even every 5 years is more attention than a lotta amps get. Have someone that understands the mechanical side (not all do) do the same, if it needs it.

    Then you'll never hafta worry.

    Comment


      #3
      Reason I like to use a COT switch besides the ramp features, you can turn the motors off during breaks.

      Maybe the motors left on chorale will aid in cooling the the amp but how long is the break? 15 minutes? Is the amp getting enough air?

      Assuming you've done your homework and made sure the motors are adjusted properly for chorale, clean, lubed and the belts and tires are not worn, the rotor assemblies are up to date and oiled, as was mentioned, the motors will last a long while.

      My first rig, had it for 15 years brand new out of the dealership, played almost every night for that period of time, never had to replace anything.

      Sold it 50 years later, still had the original Leslie parts.


      Comment


        #4
        In the world of IT infrastructure and professional installed AV (think permanent venue rigs, cruise ships, Las Vegas, etc.) the rule of thumb is that it is always better to leave gear running with as few interruptions as possible, because 90% of faults are caused at power-up.
        I've seen AV racks running on uninterruptable power supplies which literally hadn't been powered down in years.
        The other reason to keep gear running is thermal stability...... in a permanently installed venue, where the gear may be called into action at a moment's notice, it's important that the gear is already operating at thermal stability before it is needed for use.
        Another reason is inrush current - the Chief Electrical Engineer does NOT want to see 300 Amperes worth of gear being turned on and off all the time on the power network. Better that the gear is simply always on, this simplifies the load balancing calculations.

        As far as valve gear goes, thermal stability is a desirable factor - hence the standby switch on guitar amps. But where you've got motors and mechanical systems in operation, I'd err on the side of caution and turns things off during a prolonged break.
        For a 20 minute interval, I'd leave the Leslie on - you don't want to risk a power-up fault for the sake of saving 20 minutes of motor life.
        Current:
        1971 T-202 with Carsten Meyer mods: Remove key click filters, single-trigger percussion, UM 16' drawbar volume correction. Lower Manual bass foldback.
        Korg CX3 (original 1980's analogue model).
        1967 Leslie 122 with custom inbuilt preamp on back panel for 1/4" line-level inputs, bass & treble controls. Horn diffusers intact.
        2009 Marshall 2061x HW Plexi head into Marshall 4x12 cabinet.

        Former:
        1964 C3
        196x M-102
        197x X5
        197x Leslie 825

        Comment


          #5
          90% of faults are caused at power-up.
          I would agree with this. During line check which is hours before the show, the crew will leave a rig running until the end of the show. One artist crew covered the gear with blankets to warm things up even to get it "cooked" as they said.

          The COT switch turns the rotors off.

          And the rider usually calls for an extra Leslie for just in case.

          I played in a rock band 4 hours a night for years, always left the rig on. Still had the original Tungsol 6550's 50 years later and when I sold it a few months ago, I replaced the Tungsols with new Sovtek tubes but kept the Tungsols.

          Click image for larger version

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          50 year old 6550's.

          Comment


          • Papus
            Papus commented
            Editing a comment
            Of course this all goes out the window for the actual organ when you've got the likes of Jon Lord or Keith Emerson doing run-motor dive bombs.....

          • AndyPanda
            AndyPanda commented
            Editing a comment
            I've got a Leslie that's been running the same Tung-Sol for about 50 years - Leslie branded and look just like yours. Even though the Silvering on the sides has faded away - they still put out good power. Bought a set of reissue Tung-Sol and the output isn't any higher - measured slightly less than these old ones. Was planning on selling the old tubes with the Leslie (people say the faded silvering means they are garbage) but now I'm wondering if I should put the new Tung-Sol's in for the sale.

          #6
          Keith, you're Hammonding the wrong way!

          Current:
          1971 T-202 with Carsten Meyer mods: Remove key click filters, single-trigger percussion, UM 16' drawbar volume correction. Lower Manual bass foldback.
          Korg CX3 (original 1980's analogue model).
          1967 Leslie 122 with custom inbuilt preamp on back panel for 1/4" line-level inputs, bass & treble controls. Horn diffusers intact.
          2009 Marshall 2061x HW Plexi head into Marshall 4x12 cabinet.

          Former:
          1964 C3
          196x M-102
          197x X5
          197x Leslie 825

          Comment


            #7

            Of course this all goes out the window for the actual organ when you've got the likes of Jon Lord or Keith Emerson doing run-motor dive bombs.....
            Good thing those two always carried their own gear, multiples of it, and had knowledgeable Ham techs in tow.

            This doesn't happen anymore.

            Comment


            • Papus
              Papus commented
              Editing a comment
              Sadly we have seen the final days already past for people literally throwing L100's across the stage, and tilting C3's to smash the reverb tank....
              I keep the back of my studio-bound T202 accessible for crashing the reverb tank with a drumstick during studio recording sessions, there's just no other way to obtain that glorious lightning-strike sound!

            #8
            If I have to leave a Leslie running for a while, I always leave it on FAST, not slow. On Fast, the lower rotor acts as a fan to cool the amp. The Fast motors are also more rugged and less liable to wearing out than the slow motors. It's always the slow motors that go first.
            I'm David. 'Dave' is someone else's name.

            Comment


              #9
              Originally posted by David Anderson View Post
              If I have to leave a Leslie running for a while, I always leave it on FAST, not slow. On Fast, the lower rotor acts as a fan to cool the amp. The Fast motors are also more rugged and less liable to wearing out than the slow motors. It's always the slow motors that go first.
              Good to know.

              One time had an artist tech who wanted the rotors left on fast, saying the fast motors are usually stiff from little use and could use the exercise.

              Comment


                #10
                Well, the organ smashers are not gone yet, check out Sturgill Simpson ‘Call to Arms’ on SNL 8)
                Tom in Tulsa

                Fooling with: 1969 E100, 1955 M3, 1963 M100, Leslie 720

                Comment


                • ChristopherDB113
                  ChristopherDB113 commented
                  Editing a comment
                  I had never heard of this guy but looked up the SNL performance on youtube. It was like stepping back in time.

                #11
                Originally posted by tpappano View Post
                Well, the organ smashers are not gone yet, check out Sturgill Simpson ‘Call to Arms’ on SNL 8)
                I guess not...
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                Last edited by Goff; 09-09-2019, 08:47 PM.

                Comment


                  #12
                  I stumbled onto an article at sweetwater.com where their tech makes some strong claims that the need for a standby switch is a myth and the only reason Leo Fender used one was because of the voltage rating on his power supply filter caps. He thinks there is no need for standby. Curious what you guys think of this.
                  https://www.sweetwater.com/sweetcare...y-switch-myth/

                  Comment


                  • David Anderson
                    David Anderson commented
                    Editing a comment
                    I generally agree. Many amps have standby switches that do more harm than good, especially amps with GZ34 rectifiers. The vast majority of HiFi tube amps never used standby switches, and they were designed by people who knew more than guitar amp builders. Exceptions are inrush current limiters on SS-rectified McIntosh amps, possibly used because the early Si diodes couldn't handle inrush surges. The only other angle to this is that instant-on SS rectifier power supplies can potentially expose not just capacitors, but small-signal tubes like 12AX7s to excessive plate voltage at turn-on. When I have SS-rectified guitar amps with standby switches, I'll turn them on in standby. I don't do this with tube-rectified amps. In fact, many standby switches in guitar amps are terrible for tube rectifiers. Some Sunn amps come to mind.

                    Some techs have modified standby switches to be low-voltage switches, putting a large dropping resistor in series with the power supply. Thus, someone can lower the voltage on tubes or implement slow start without the same problems as the all-or-nothing designs.

                    I'm trying to think of a Gibson amp with standby, and I'm not coming up with anything. Maybe some later ones did.

                  #13
                  Always left mine on all evening, right through the breaks. Never sure whether to leave it on chorale - less strain on bearings - or tremolo - cooling for the amp and no undue wear on the slow motor and rubber tyre. Eventually added a 'stop' function to one of the 145s and just let its amp stay warm. No problems with any of the leslies mentioned in the signature, over many years. All left on during gigs.
                  It's not what you play. It's not how you play. It's the fact that you're playing that counts.

                  New website now live - www.andrew-gilbert.com

                  Current organ: Roland Atelier AT900 Platinum Edition
                  Retired Organs: Lots! Kawai SR6 x 2, Hammond L122, T402, T500 x 2, X5. Conn Martinique and 652. Gulbransen 2102 Pacemaker. Kimball Temptation.
                  Retired Leslies, 147, 145 x 2, 760 x 2, 710, 415 x 2.

                  Comment


                    #14
                    It seems that the best solution would be a stop on the motors ir a power cut switch and use a small fan on the amp on those outdoor gigs when its 90* or higher.

                    Comment


                      #15
                      On a 145/7, just wire a mains capable switch across the small jumper plug on the chassis (I used a spare half moon, in the days when there were plenty of them!) and that gave you stop instead of chorale (and also that lovely, un-braked, wind down of the lower rotor to a stop).
                      It's not what you play. It's not how you play. It's the fact that you're playing that counts.

                      New website now live - www.andrew-gilbert.com

                      Current organ: Roland Atelier AT900 Platinum Edition
                      Retired Organs: Lots! Kawai SR6 x 2, Hammond L122, T402, T500 x 2, X5. Conn Martinique and 652. Gulbransen 2102 Pacemaker. Kimball Temptation.
                      Retired Leslies, 147, 145 x 2, 760 x 2, 710, 415 x 2.

                      Comment


                      • Papus
                        Papus commented
                        Editing a comment
                        That'll put 110V across your wiring and the switch - my 122-V came to me fitted with a footswitch wired to the brake accessory plug on the amp chasiss!
                        Even worse than that: it was wired to a 1/4" jack on the back panel of the Leslie! - imagine if some unsuspecting sod plugged their guitar into that, putting 110V through their strings, or if they plugged a speaker into it, or the line input or output of a mixing desk!
                        And EVEN WORSE - the 1/4" jack was on a metal plate about the size of a cigarette packet..... wandering hands could easily touch it.... ZAP!
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