PT and OT wiring question. Best practices.

[olgoat]

My first 5E3 has been working fine but I want to change out the OT for a multitap OT (Classic Tone 40-18090 4/8/16 ohm). 

I (probably foolishly) ordered a new Mag Components Classic Tone PT to go along with it. The original PT I put it was a 650 (325V per side).  This Classic Tone PT (40-18078) can be wired for either 330V or 355V per side. It also can be wired for 100, 120, 220,230 or 240V.  I just need 120V

To my questions on best practices here.

• What is the best thing to do with the unused leads for both the PT and OT?
• Should I coil the unused OT wires outside the chassis where the OT mounts or coil them inside?
• Do you cut the PT and OT leads short if there is excess wire to keep things neat in the chassis?  I cut the wires short on the first PT and OT but didn't have a good feeling about it.

.

Thanks for any thoughts on the matter.  I don't know which PT voltage I am going to like at this point so I am leaving my options open.

[PRR]

If unused wires have been stripped, cut copper back to insulation, then use an inch of shrink-tube to seal the end against accidents.

I would not cut-short until the 2nd or 3rd prototype... in a one-off, there will always be later changes. Coil the unwanted leads neat with a couple wire-ties.

For an amp which will/may leave home, I would not leave stray ends outside the chassis. Tuck them inside away from beer-spills. For a home-amp with no cats nor kids around, the stray low-impedance ends can lay around. Any stray OT plate taps and all PT stray taps should be inside for your safety.

[olgoat]

Thanks.  I'll coil em up as best I can.  I have too many options with this transformer.  Big mistake.  100, 120, 220.230 and 240 on the primary side and 355-0-355 or 330-0-330 on the secondary.  what a mess..

I wanted the option of trying two different secondary voltages but that only came with the multitap primary.  

Tim

[stingray_65]

It's common practice to coil the wires up and tuck them away.
the choices are always there should you want to "hot rod" or mod the amp.

While I've not had any issue with this on the PT, I have had an issues when tucking spare wires on the OT.

Once mind you just one time. the spares I wound up on the OT caused a weird oscillation. Was a devil to trouble shoot! moved the wires and the amp sounded great.

[Boots Deville]

+1 for Ray's experience.

Just last month I had an Edcor OT that had ultralinear taps I wasn't using.  I had them tied off and tucked under the turret board.  They happened to be too close to V1 and caused oscillation.  Spend a few evenings troubleshooting before I found it.  Once I moved those wires the amp sounded great and the world was a happier place.

Incidentally, my "best practice" with these is to create a small loop in the end of the unused wire and use heatshrink to hold the loop closed and cover the end.  This loop makes a nice "handle" to zip tie the wires to something, if needed to hold in place.

[Ed_Chambley]

I put 2 standoffs on the chassis to the back side of the transformer, away from the tubes.  Put a fender washer on top of them.  Shrinkwrap the ends. Under the standoffs, I put a cut piece of fiberboard and zip tie this to the wires.  Makes a nice cover.  Wrap one color at a time and zip strap it.  then on and on.  Looks neat and keep stray currents behind the transformer.  Of course on Multi-tap OT, I use them all.

[jojokeo]

OT secondary wires are important to keep short, direct, and away from as much as you can (best practices).