Finally

[v846]

John,

Did this help? for something quick & dirty I stuffed some rubber grommets under the PT feets, very slight reduction of the vibration but the hum in the signal path remains. The PT buzz sounds like a noisy fluorescent lamp ballast ..

Thanks,
David

[v846]

Got to play the amp full up yesterday, wow what a beautiful noise
Using a Marshall 4X12 with G12M 25 watt speakers and a strat with a 20 foot Mogami cord/Neutrik jacks.

Tubes are an EI for V1, Amperex Bugleboy V2, and Tungsgram for V3. EL34’s are RFT that are an old set of Groove tubes Grade 5 I had kicking around still in decent health.

Still have some issues to iron out before getting a cab for it but very pleased with the tone and response.

[Structo]

The Magnetic Components PT in my Dumble clone has some humming to it when I power it up.

It has the copper flux band like the Heyboer's do.

Not sure what causes that, it's some sort of inductive coupling I think.

Aluminum chassis so it is not that.

It isn't noticeable at all once I go off standby and play.

[pablogt]

I have the same buzzing Heyboer PT in my Rocket. Did the O rings trick work?

Pablo

[v846]

Hi Tom,

It looks like I have two different things going on. First is a very audible buzz coming from the PT, enough that it vibrates the chassis.
I did move the OT around some but no difference. The hum band on this iron is applied loosely, could that contribute to the buzz? I’ll probably remove the PT to see how much it buzzes on its own.

The second is I’m getting hum in the signal path which is volume dependent mostly with the vol past 2 o’clock & bass turned up past noon.
Not sure it that’s related to the first problem or if I messed up on my wiring somewhere, still looking into it.

Pablo,
Yeah it dampened some chassis vibration but not the audible buzz.

Thanks,
David

[Structo]

I thought perhaps the PT and OT were too close to one another but in looking at the photos of the real deal they are pretty close.

Do you have the NOS broom handle between the two transformers as shown?

[v846]

Haha well actually I do have some promising looking dowels around here that are to prop up the old windows

[MCK]

I'm sure my wife will not notice that the broomstick is now an inch or so shorter...

[v846]

Here we , this will do nicely

I tried a hum balance pot and only a slight reduction. Also Went through all my tubes with no change, either my ECC83's aren't up to the task or there is something else causing the hum, search continues.

David


[IMG:640:480]http://i270.photobucket.com/albums/jj10 ... C06035.jpg[/img]

[Reeltarded]

Congrats on the wife not noticing the missing inch..

[v846]

knew that was coming..

heater voltage is a bit high with 120 at the wall I get almost 6.7VAC, I might run the heaters off a battery just to eliminate that as a possible cause?

[MCK]

Congrats on the wife not noticing the missing inch..

Nothing a little hotter biasing will not mask...

[MCK]

knew that was coming..

heater voltage is a bit high with 120 at the wall I get almost 6.7VAC, I might run the heaters off a battery just to eliminate that as a possible cause.

With or without the tubes? I also saw higher readings during my initial testing without the tubes but once the load came on the voltages dropped down nicely... Running off batteries might be a problem since these are real high current devices. EL34 for example is 1.5Amps on the heater and you have 2 of those + the preamp tubes... Tough load.

[v846]

that's with tubes installed, sounds like a dc supply would be a better bet running that test.

[Dr-Joned]

[quote="MCK"]I'm sure my wife will not notice that the broomstick is now an inch or so shorter... [/quote]


I hope it doesn't cause any navigation problems!