The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Dynaco VTA tube amp kits, all Tubes4hifi.com products and all Dynakitparts.com products


    Weird whooshing sound on M-125

    Share

    Bob Latino
    Admin

    Posts : 2378
    Join date : 2008-11-26
    Location : Massachusetts

    Re: Weird whooshing sound on M-125

    Post by Bob Latino on Sun May 18, 2014 7:26 pm

    Re: "Bob, I am getting a bit of hum out of that channel -- it was there before I replaced the tubeage"

    The most common cause of any hum/noise in the M-125's is the FRONT driver tube. Swap the front (voltage amplifier tube) for the rear (phase splitter/inverter) tube and see if the hum/noise goes up or down. If it goes either way, you can almost be assured that the hum/noise is tube related. The other possibility could be a partial contact situation on any of the tube pins in the amp. Also, you might try wiggling slightly your interconnects where they connect the preamp to the amp ..

    Bob

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Weird whooshing sound on M-125

    Post by deepee99 on Sun May 18, 2014 7:28 pm

    Bob, I'm thinking interconnects. I will think more clearly after another bottle of Scotch. But then, out comes the fire extinguisher, and I just put it away . . . somewhere.

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Weird whooshing sound on M-125

    Post by deepee99 on Sun May 18, 2014 7:32 pm

    And at any rate, I have really cool-looking silver getter-flashing again. Perfection, such a tedious process.
    But I'm still not turning my back on these dudes for awhile. Skizo, can you you e-mail me some fire-retardant, in case I can't find the extinguisher in the kitchen, or reach it from the floor?

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Well, the belching and pharting noises . . .

    Post by deepee99 on Sun May 18, 2014 8:53 pm

    . . . have gone away, as has the hum. I  think Bob is right, I've got a hinky bit of coax; lots more of that around here to sub-out with, but not tonight. Also, I guess it takes a bit of time for the tubes and caps to get acquainted.  The Wallace Volunteer Fire Department is standing down are they're now back at the Metals Club bar to celebrate saving another lot.
    I'm all in for MontanaWay's TubeFest, but ID should be required. May I propose propeller hats? That should separate us from the chaff.
    Jim McShane, I rescued your old 120s and RCA drivers from the Dumptster, and will keep them as back-ups. Still, I think upwards of 3-4k hours on a rack of tubes is money well spent. And I push these babies hard.
    No, I'm not bringing the 500-lb Vandersteens to TubeFest, but would be willing to negotiate a swap of well made woody M-125s for my metal ones. After all, if it ain't broke, go break it. Or, to quote Red Green, if you can't be handsome, be handy.

    Jim McShane

    Posts : 154
    Join date : 2011-10-19
    Location : South Suburban Chicago

    Re: Weird whooshing sound on M-125

    Post by Jim McShane on Sun May 18, 2014 9:04 pm

    deepee99 wrote:Jim McShane, I rescued your old 120s and RCA drivers from the Dumptster, and will keep them as back-ups. Still, I think upwards of 3-4k hours on a rack of tubes is money well spent. And I push these babies hard.

    I agree, no question.

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Here's a shot of 3k hour KT-120s vs 25 hour KT-120s

    Post by deepee99 on Thu May 22, 2014 4:48 pm



    Obviously, the old boys are on the right.

    Jim, was I too early in pulling them?

    MontanaWay

    Posts : 767
    Join date : 2014-02-06
    Age : 58
    Location : Cameron, Montana

    Re: Weird whooshing sound on M-125

    Post by MontanaWay on Fri May 23, 2014 11:29 pm

    oh I see your problem!!!...your tube damper rings are all over the place...no wonder you got problems!!!!!  What a Face 

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Weird whooshing sound on M-125

    Post by deepee99 on Sat May 24, 2014 10:38 am

    You'd be surprised what asymmetrical tube ring arrangements can accomplish. Actually, I'm not sure they accomplish a bloody thing.

    MontanaWay

    Posts : 767
    Join date : 2014-02-06
    Age : 58
    Location : Cameron, Montana

    Re: Weird whooshing sound on M-125

    Post by MontanaWay on Sat May 24, 2014 11:21 am

    deepee99 wrote:You'd be surprised what asymmetrical tube ring arrangements can accomplish. Actually, I'm not sure they accomplish a bloody thing.

    well if nothing else, they can be a point of interesting discussions!!  Wink 

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Weird whooshing sound on M-125

    Post by deepee99 on Sat May 24, 2014 11:22 am

    MontanaWay wrote:
    deepee99 wrote:You'd be surprised what asymmetrical tube ring arrangements can accomplish. Actually, I'm not sure they accomplish a bloody thing.

    well if nothing else, they can be a point of interesting discussions!!  Wink 

    Including my neighbor, something of a tube sage, who noticed them and said, "You didn't fall for that crap, did ya?"

    MontanaWay

    Posts : 767
    Join date : 2014-02-06
    Age : 58
    Location : Cameron, Montana

    Re: Weird whooshing sound on M-125

    Post by MontanaWay on Sat May 24, 2014 11:24 am

    deepee99 wrote:
    MontanaWay wrote:
    deepee99 wrote:You'd be surprised what asymmetrical tube ring arrangements can accomplish. Actually, I'm not sure they accomplish a bloody thing.

    well if nothing else, they can be a point of interesting discussions!!  Wink 

    Including my neighbor, something of a tube sage, who noticed them and said, "You didn't fall for that crap, did ya?"


    hehehehehehehehe......perception is an interesting thing!  Razz 

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Yes, but back on topic, no joy yet

    Post by deepee99 on Tue May 27, 2014 11:43 am

    Neither a swap-out of tubes (drivers and outputs) or coaxial leads has solved this periodic static coming out of the left channel. It's like a packet-burst of modulated hash, like RF. It does seem to increase in frequency of occurrence after the amps have been on for several hours, but not always.
    Could a cell tower or some other gizmo in the neighborhood be causing this? I don't have any hams living nearby.
    Bias, voltages, etc., all normal. It's independent of the pot settings on the preamp, and occurs on all sources.
    Any theories out there? It hasn't gotten worse; it just persists.
    Many thanks for suggestions.





    corndog71

    Posts : 444
    Join date : 2013-03-19
    Location : It can get windy here

    Re: Weird whooshing sound on M-125

    Post by corndog71 on Tue May 27, 2014 1:05 pm

    Are you sure it's not the preamp?

    sKiZo

    Posts : 1285
    Join date : 2013-04-01
    Location : Michigan USA

    Re: Weird whooshing sound on M-125

    Post by sKiZo on Tue May 27, 2014 2:07 pm

    Reminds me of a famous quote ...

    "I love deadlines. I love the whooshing sound they make as they go by."

    Douglas Adams

    In the interest of being semi-useful (sorry - a semi is about all I can get up today) ...

    If it IS sporadic (not to be confused with intermittent) I'd also consider external interference as the culprit. Try rearranging (or even switching, not to be confused with cycling) speaker cables and interconnects and see if that helps. I'd also hunt for other appliances that could be cycling (not to be confused with switching) at the same time the noise appears.

    As an aside, my computer was driving me nuts, making these bizarro noises that sounded like a clogged fan bearing. Took the cover off twice to spray air, but no improvement. I'd resigned myself to replacing the fans, and went to get a cuppa coffee to steel myself for the effort. Walking back, I noticed the indicator light on a Riddex pest repeller flashing in time to the noise. Unplugged that ... problem solved.

    Speaking of driving me nuts ...

    https://www.youtube.com/watch?v=f-lu4E246AI

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Weird whooshing sound on M-125

    Post by deepee99 on Tue May 27, 2014 4:57 pm

    sKiZo wrote:Reminds me of a famous quote ...

    "I love deadlines. I love the whooshing sound they make as they go by."

    Douglas Adams

    In the interest of being semi-useful (sorry - a semi is about all I can get up today) ...

    If it IS sporadic (not to be confused with intermittent) I'd also consider external interference as the culprit. Try rearranging (or even switching, not to be confused with cycling) speaker cables and interconnects and see if that helps. I'd also hunt for other appliances that could be cycling (not to be confused with switching) at the same time the noise appears.

    As an aside, my computer was driving me nuts, making these bizarro noises that sounded like a clogged fan bearing. Took the cover off twice to spray air, but no improvement. I'd resigned myself to replacing the fans, and went to get a cuppa coffee to steel myself for the effort. Walking back, I noticed the indicator light on a Riddex pest repeller flashing in time to the noise. Unplugged that ... problem solved.

    Speaking of driving me nuts ...

    https://www.youtube.com/watch?v=f-lu4E246AI

    Now that was sick and wrong. Love it!

    About the only intermittent and unpredictable appliance here is the refrigerator. I suppose the satellite dish receiver does weird things from time to time as well. Well, more hunting is in order.
    I get the same periodic racket with the pre-amp shut off. And it's not coming from the Vandersteen subwoof because it's on all the time.

    Or maybe . . . https://www.youtube.com/watch?v=2OciCzKgGY0



    sKiZo

    Posts : 1285
    Join date : 2013-04-01
    Location : Michigan USA

    Re: Weird whooshing sound on M-125

    Post by sKiZo on Tue May 27, 2014 5:52 pm

    Another trick for intermittent noise is to run a common ground between the pre and the amp, then to house. That can act as a drain and hopefully keep ... whatever ... from building to the point where it discharges ...

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Weird whooshing sound on M-125

    Post by deepee99 on Tue May 27, 2014 6:22 pm

    sKiZo wrote:Another trick for intermittent noise is to run a common ground between the pre and the amp, then to house. That can act as a drain and hopefully keep ... whatever ... from building to the point where it discharges ...

    Thanks, Skiz. I will give that a shot. It's actually a light bzzzzzz more than the sort of whoosh a funky capacitor or tube would make.
    So at present, I have the L.H. amp lit, preamp off . . . and the refrigerator door open, warming my beer to English temperatures, to see if its cycling has anything to do with this lot. Back in my amateur radio days, my Collins S-line would go bug-nutty if I fired up the new computer (the venerated 8086) in the same room, and also generated weird noises when the fan-motor on the pellet stove lit off. We live with a lot more RF than we used to.

    I'll hook up a spade connector to one of the chassis screws on the M-125 to the pre-amp, see what happens. A variable occurs, just thinking about this, that this RF/whatever happens more often in the evening than during the day. (A third track of thought has been that I should re-butter some of the solder connex underneath the amp, but they get just as warm in the morning as they do at night -- so I don't think it''s there.)

    These things are sent to teach us patience and humility. Or as an old Seattle Times editor used to tell me, "Don't tell me which part you liked best."



    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Weird whooshing sound on M-125

    Post by deepee99 on Tue May 27, 2014 7:14 pm

    corndog71 wrote:Are you sure it's not the preamp?

    Corndog,
    I don't think so; I did a tube-swap there, too. If this thing would just settle down and bzzzzzz all the time I could locate it. It's like solving a multi-variable equation, or starting my wife's '66 Mustang in the winter. Ya just never know till it blows up, quits, or fails utterly; then at least you have a starting point.
    Maybe there's a CB'er in the neighbourhood with a 2kw booster who drives by occasionally.


    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Weird whooshing sound on M-125

    Post by deepee99 on Tue May 27, 2014 10:43 pm

    No bzzzzzzzzzzz since I unplugged the refrigerator.
    So the choice may be between hot beer, limp lettuce and rotten meat, or clean sound. Except in winter when the reefer (the machine that cools stuff) is vestigial.

    Think I will go smoke a tomato plant and meditate upon this for a while -- while listening to tunes, of course, not wishing to skew the results.

    Guess I could get used to warm Rainier in the summer....


    GP49

    Posts : 718
    Join date : 2009-04-30
    Location : East of the sun and west of the moon

    Re: Weird whooshing sound on M-125

    Post by GP49 on Tue May 27, 2014 11:33 pm

    Hopefully what happened to me won't happen to you:

    It was Thanksgiving week about fifteen years ago.  I noticed a buzzing on weak-signal radio reception on the kitchen radio.  "Funny, it never did THAT before."

    Three hours later there was a funny smell in the kitchen.  The motor-compressor unit of the refrigerator had failed; the motor section had burned up.  

    That did it.  I had to look for someone who could deliver us a new refrigerator on Thankgiving Week!  In the meantime, I got about twenty pounds of dry ice to keep the turkey and the other fixin's from going bad...

    Sears, Home Depot, the "anybody can get credit" appliance stores would have to get one "from the warehouse" which would take a week.  Fortunately a local Maytag appliance dealer had one in stock that could be delivered next day.

    The holiday was saved.  Unfortunately, spending on the hi-fi had to stop for a while.

    This, of course, has nothing at all to do with a weird whooshing sound on an M-125.... confused

    Sponsored content

    Re: Weird whooshing sound on M-125

    Post by Sponsored content Today at 2:43 am


      Current date/time is Thu Sep 29, 2016 2:43 am