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    First amp project

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    Ernstmach

    Posts : 28
    Join date : 2015-08-30
    Location : Lower Michigan

    First amp project

    Post by Ernstmach on Fri Apr 01, 2016 9:57 am

    Have been wanting to try putting an amp together for some time.
    My first go was a pair of MK3's. I did make a couple of changes, moving connections to the rear and going with an IEC for power.
    As can be seen these are paired up with my Aretha preamp from Tube Nirvana.

    Thanks very much to Bob Latino for some help and advice.
    These fired up with no problems, tubes biased and sound great!
    Powering my Focal speakers very nicely..


    Kentley

    Posts : 335
    Join date : 2015-03-06
    Age : 64
    Location : Worcester, MA

    Re: First amp project

    Post by Kentley on Fri Apr 01, 2016 10:12 am

    Beautiful! You must be a proud papa.

    deepee99

    Posts : 1333
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: First amp project

    Post by deepee99 on Fri Apr 01, 2016 11:01 am

    Stone-cold beautiful. I agree with Kentley even though we are of different political parties.
    Is that an old J-3 prop hanging there?

    sKiZo

    Posts : 1310
    Join date : 2013-04-01
    Location : Michigan USA

    Re: First amp project

    Post by sKiZo on Fri Apr 01, 2016 4:45 pm

    Very nice! Clean and simple ...

    The triangle on the front panel is the bias taps?

    PS ... where's "lower Michigan"? I'm just north of Grand Rapids ...

    Ernstmach

    Posts : 28
    Join date : 2015-08-30
    Location : Lower Michigan

    Re: First amp project

    Post by Ernstmach on Fri Apr 01, 2016 5:44 pm

    Thanks everyone!
    I'm pretty happy with them.

    The prop is from an rpv used in Vietnam during the conflict. Picked up in a surplus store.

    Yes those are the bias taps on the front

    Lower Michigan, Tecumseh to be more specific..

    Ernstmach

    Posts : 28
    Join date : 2015-08-30
    Location : Lower Michigan

    New amp build

    Post by Ernstmach on Sun Apr 03, 2016 10:24 am

    I wanted to ask if someone might have some advice for me?
    The amps are starting to settle in but I have not been able to find a cause for the buzz I'm hearing from the speakers when nothing is playing.
    I have triple checked all of the ground connections. All solder joints are nice and bright.
    The buzzing is only audible from the speakers. Transformers are quiet.

    Thanks for any advice!

    Kentley

    Posts : 335
    Join date : 2015-03-06
    Age : 64
    Location : Worcester, MA

    Re: First amp project

    Post by Kentley on Sun Apr 03, 2016 10:48 am

    The first thing you should do is ascertain which component is causing the hum. Easy - work back from the power amps by pulling your
    interconnects from the M-125s. Best to do this with the power off. If no hum, then work backwards by successively plugging in each component in the chain one by one. When the hum appears, you will know where it's coming from - and don't ignore the possibility that it's from an interconnect cable.
    Phono stages are extremely sensitive because of the low voltages involved. Don't hesitate to experiment with physical layout of your system. Sometimes merely moving components or wires can alleviate a hum problem.
    If you try all this, and narrow down the culprit, then it's time for more experienced aid than that I am capable of offering. Good luck.

    Ernstmach

    Posts : 28
    Join date : 2015-08-30
    Location : Lower Michigan

    Re: First amp project

    Post by Ernstmach on Sun Apr 03, 2016 11:08 am

    Kentley,
    thanks for that, I did disconnect the ic's, one at a time and the buzz became louder. Same from both amps.

    With everything hooked up the buzz does not grow more loud with higher volume setting...

    Sounds like some of the older fluorescent lights make.

    Kentley

    Posts : 335
    Join date : 2015-03-06
    Age : 64
    Location : Worcester, MA

    Re: First amp project

    Post by Kentley on Sun Apr 03, 2016 11:16 am

    How's your house AC power? Sounds like that might, unfortunately, be at fault. Search this forum for various opinions on this problem. There's no one simple solution, apparently. The fact that BOTH amps have the same identical problem, it seems, points to the incoming AC. Ick.

    Ernstmach

    Posts : 28
    Join date : 2015-08-30
    Location : Lower Michigan

    Re: First amp project

    Post by Ernstmach on Sun Apr 03, 2016 11:20 am

    The house current is pretty stable. I also have the amps hooked to a power conditioner. Previous tube amp was dead quiet..

    Probably a self induced problem while assembling the amps.

    Kentley

    Posts : 335
    Join date : 2015-03-06
    Age : 64
    Location : Worcester, MA

    Re: First amp project

    Post by Kentley on Sun Apr 03, 2016 11:22 am

    If house current is stable, try bypassing the conditioner. Those things are not foolproof solutions.

    Ernstmach

    Posts : 28
    Join date : 2015-08-30
    Location : Lower Michigan

    Re: First amp project

    Post by Ernstmach on Sun Apr 03, 2016 11:51 am

    Have bypassed the power conditioner and I'm still hearing the buzz but at a reduced level.
    About half as loud if that makes any sense..

    Kentley

    Posts : 335
    Join date : 2015-03-06
    Age : 64
    Location : Worcester, MA

    Re: First amp project

    Post by Kentley on Sun Apr 03, 2016 11:57 am

    That makes no sense to me, but I think you're getting warmer. Calling Dr. Latino to the E.R. STAT!!!

    Bob Latino
    Admin

    Posts : 2411
    Join date : 2008-11-26
    Location : Massachusetts

    Re: First amp project

    Post by Bob Latino on Sun Apr 03, 2016 12:11 pm

    Some power conditioners do not output a true sine wave. You should probably run the amps directly off a wall outlet OR a power strip plugged directly into a wall outlet.

    The fact that the buzzing noise is reduced with the amps plugged into a wall outlet is a clue that possibly there could be an issue with your power conditioner ? Try not using the power conditioner with ALL the components in your music system.

    If you are getting a buzzing noise and your Mark III's use a 3 wire power cord, try floating the ground on both amps with a 3 prong to 2 prong "cheater plug". Lifting the ground wire may help with the buzzing noise you are getting ..

    Bob

    Ernstmach

    Posts : 28
    Join date : 2015-08-30
    Location : Lower Michigan

    Re: First amp project

    Post by Ernstmach on Sun Apr 03, 2016 12:12 pm

    Thanks for your help Kenley and Bob.
    I'll give that a try.
    Bob

    Ernstmach

    Posts : 28
    Join date : 2015-08-30
    Location : Lower Michigan

    Re: First amp project

    Post by Ernstmach on Sun Apr 03, 2016 12:27 pm

    Floating the ground has solved the problem!

    Thanks for the suggestions!

    deepee99

    Posts : 1333
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: First amp project

    Post by deepee99 on Sun Apr 03, 2016 12:34 pm

    Ernstmach wrote:Floating the ground has solved the problem!

    Thanks for the suggestions!
    Ernst,
    You're not the only pilot on this forum who has had a ground loop problem.

    Ernstmach

    Posts : 28
    Join date : 2015-08-30
    Location : Lower Michigan

    Re: First amp project

    Post by Ernstmach on Sun Apr 03, 2016 12:45 pm

    deepee99 wrote:Ernst,
    You're not the only pilot on this forum who has had a ground loop problem.

    Nice!

    Tube Nube

    Posts : 641
    Join date : 2008-12-06
    Age : 53
    Location : Calgary, AB

    Re: First amp project

    Post by Tube Nube on Sun Apr 03, 2016 8:25 pm

    Oh, oh, me thinks that's a reference to a certain pilot on this board who has had 2 ground loops, and one, no less, right after the other!

    deepee99

    Posts : 1333
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: First amp project

    Post by deepee99 on Mon Apr 04, 2016 7:17 am

    Or as another Forum member's flight instructor once admonished him: "That wasn't a landing. That was a controlled crash."
    Kinda boring around here. Haven't blown-up any electronics for several months.

    GP49

    Posts : 733
    Join date : 2009-04-30
    Location : East of the sun and west of the moon

    Re: First amp project

    Post by GP49 on Mon Apr 04, 2016 2:24 pm

    The oft-heard advice to "ground everything" by using three prong AC plugs on everything has probably been responsible for more ground loops than anything else except Cable TV grounds.  EVERY separate cord, when combined with the grounds in the audio cabling, is another ground loop, and each has the potential to cause hum...or, a Buzz.  Ground loops generally sound like a buzz; defective power supply capacitors, like a smooth Hummmmm.

    peterh

    Posts : 679
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: First amp project

    Post by peterh on Mon Apr 04, 2016 3:19 pm

    I must have a problem here, all units connected with grounded outlets, and no hum. What's the problem ??

    audiobill

    Posts : 270
    Join date : 2014-03-13
    Location : Philadelphia

    Re: First amp project

    Post by audiobill on Mon Apr 04, 2016 3:25 pm

    Need to turn power on

    Kentley

    Posts : 335
    Join date : 2015-03-06
    Age : 64
    Location : Worcester, MA

    Re: First amp project

    Post by Kentley on Mon Apr 04, 2016 3:57 pm

    ...or get a buzz on...

    peterh

    Posts : 679
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: First amp project

    Post by peterh on Mon Apr 04, 2016 4:31 pm

    audiobill wrote:Need to turn power on

    I have a count basie record playing, still no hum :-)



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