First amp project

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..

Beautiful! You must be a proud papa.

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

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 ...

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..

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!

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.

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.

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.

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.

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

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..

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

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

Floating the ground has solved the problem!

Thanks for the suggestions!

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.

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

Nice!

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!

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.

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.

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

Need to turn power on

...or get a buzz on...

audiobill wrote:Need to turn power on

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