Rectifier limiting resistors

[Ross]

In the Amperex spec sheet for the 5AR4 tube, current limiting resistors are called for in capacitor filtered circuits though I've yet to see them in guitar amp schematics. Am I missing something?

[pdf64]

Vintage transformers were designed to incorporate such resistance into the HT winding. With modern transformers, you have to check. It’s perceived as a bad thing for transformers to get warm in use, so manufacturers seem to try to reduce such copper losses where feasible. I’ve seen some modern amp designs with additional resistors.

[tubeswell]

Am I missing something?

I take it you read 1/2 way down this page? http://www.valvewizard.co.uk/bridge.html


I think 'traditional' guitar amps didn't have these because tube rectifiers (and PTs) are generally rugged enough to handle abuse. (Plus current limiting resistors on the HT winding steal a bit of B+ voltage)

[HotBluePlates]

Vintage transformers were designed to incorporate such resistance into the HT winding. ...

I think 'traditional' guitar amps didn't have these because tube rectifiers (and PTs) are generally rugged enough to handle abuse. ...

I used to own a 1964 Deluxe Reverb.  I measured its power transformer, and it had significantly higher winding resistance than modern replace PTs.  I also didn't get the undesired-high-B+ voltage, and found that amp expected 120vac on the primary.

I suspect the higher winding resistance gives a subtly softer attack to the sound, as it would contribute slightly to sag/compression.