Dumb question re: mounting PT

[rogb]

http://www.mercurymagnetics.com/images/ ... leFlat.pdf

Note: When attaching a flat
mount to the chassis
run the nuts and washers
UNDER the chassis.
Do not use a separate set
of nuts to suspend
the transformer over
the chassis.

[M Fowler]

Ah what does Mercury know

Whatever method floats your boat (in this case transformer) works.

Unscrew the nuts and mount it flat or keep the nuts on and slide a washer on than use another washer and nut on bottom. Both methods work.

So those companys old and new that did not read the Mercury instructions made uninformed decision, huh

Mark

[martin manning]

Where's the reasoned argument for this recommendation from Mercury? Without that, it's just somebody's personal preference.

The cases where the transformer has torn out are doubtless due to a large g-load (aka droping the amp), especially when the transformer hangs under the chassis.

For reinforcement, washers on the inner side might help some but the full square doubler is structurally much better. I can't see any reason putting nuts between the transformer and chassis is a problem, and it might minimize flux leakage if the chassis is steel.

[rogb]

Where's the reasoned argument for this recommendation from Mercury? Without that, it's just somebody's personal preference.

The cases where the transformer has torn out are doubtless due to a large g-load, aka droping the amp, especially when the transformer hangs under the chassis. For reinforcement, washers on the inner side might help some, but the full square doubler is structurally much better. I can't see any reason putting nuts between the transformer and chassis is a problem, and it might minimize flux leakage.

Ok, interesting points.

How do you feel about Mercury's statement about using the UM mount making the transformer quieter - more snake oil stuff?

[kbperry810]

All possible pros and/or cons set aside... a great deal of the laydown transformers I've used these nuts were practically "glued" in place... I started using a second set and leaving these as spacers out of convenience and/or out of fear of doing more harm than good trying to remove them. `

[martin manning]

rogb, help me out here, what's a UM mount?

Edit, ok got it, "UTM" mount:

"By using the two pass-through bolt channels of the transformer (instead of the standard four bolts corner bolts through the laminations) the mount reduces magnetic interference making the transformers run quieter -- ideal for recording purposes."

I buy this, it's adding a third bolt to tie the chasis to the transformer core along each long side. This will stop the chassis sheet metal between the corner bolts from vibrating and making noise, if that is an issue. If you put nuts between the transformer and the chassis, it won't be ;^)

[loctal]

I would never mount a Mercury transformer to any amp that i built.

[overtone]

Martin and ToneMerc are right, the photo I posted on page one shows a really very heavy transformer, mounted hanging down, with undersized washers and it most certainly took a large fall at some point. You can see the dent in the headshell which stopped the PT from going into low level orbit.

Thank you for the clarification of the "english" bracket supports method and the links to the UTM frame. Up until now I have retro-fitted stainless bolts and really huge washers. I always wanted to have a four sided reinforcement on the inside of the cutout too - and there it was, on the PT itself, staring at me right in the face all the time!

Feeling nutty, tony

[rdjones]

http://www.mercurymagnetics.com/images/ ... leFlat.pdf

Note: When attaching a flat
mount to the chassis
run the nuts and washers
UNDER the chassis.
Do not use a separate set
of nuts to suspend
the transformer over
the chassis.

The only reason I'd question MM's suggestion is why would they go to all the expense and effort to clone a vintage transformer as closely as possible and then turn around and tell you to change the mounting method.

The few chassis I've seen that had impact damage probably wouldn't have been helped by one method over the other, except possibly using large sheet metal body washers under the chassis to distribute force. (not a bad idea if you expect rough handling)

rd

[BobW]

Where's the reasoned argument for this recommendation from Mercury? Without that, it's just somebody's personal preference.

The cases where the transformer has torn out are doubtless due to a large g-load (aka droping the amp), especially when the transformer hangs under the chassis.

For reinforcement, washers on the inner side might help some but the full square doubler is structurally much better. I can't see any reason putting nuts between the transformer and chassis is a problem, and it might minimize flux leakage if the chassis is steel.

I totally agree w/ Martin. Transformers pull out of a chassis not because an additional set of nuts are used to mount it. Usually it's because the chassis gauge selected was too thin to begin with, and to withstand a reasonable shear force. Mounting the transformer using the supplied nuts would help protect it from shock only if the force applied was directly from the top of the transformer down onto the chassis. However mounting this way, doesn't provide any additional support for forces applied in any other direction, since the nuts are being pulled. As Martin suggested, washers on the inside would provide a better support AND might minimize any flux leakage. fwiw, I always add nuts and have never had a problem with noise or pulled chassis.