Rectifier Question

Kent747

I have an older Dr Z M12 and it was time for a valve replacement. I checked the Z website, and Watford Valves (amongst others) and ordered new tubes. 

Specifically I ordered a 5AR4 rectifier - as listed on the sites. However when I pulled the rectifier, it was a 5Y3S. I noticed a different Z manual also lists the 5Y3. 

Anyone know what difference if any it may make? I am reading up on voltage delivery but should I expect significant changes or imperceptible (akin to tone wood or magic diodes)?

ecc83

I don't know what rectifier that amp should have but a 5AR4 is a GZ34 and that is more efficient than the 5Y3 (less voltage drop) . People bang on about "sag" and "compression" but in terms of the rectifier valve used it is IMHO largely BLLX! Solid state rectifier might make a diff if you can directly compare them to a GZ. In any case there is more to an amp's power supply than the rectifier. "Sag" will be influenced by the value of the filter caps and to some degree whether the amp uses a choke.

Dave.

Kent747

ecc83 said:

I don't know what rectifier that amp should have but a 5AR4 is a GZ34 and that is more efficient than the 5Y3 (less voltage drop) . People bang on about "sag" and "compression" but in terms of the rectifier valve used it is IMHO largely BLLX! Solid state rectifier might make a diff if you can directly compare them to a GZ. In any case there is more to an amp's power supply than the rectifier. "Sag" will be influenced by the value of the filter caps and to some degree whether the amp uses a choke.

Dave.

It’s definitely ‘tighter’ which is such a ridiculous phrase to say, but it’s true. 

I am not sure what it’s supposed to have now either given the differing details from the Z site. 

ICBM

A GZ34/5AR4 will produce higher voltages throughout the amp and less sag when driven hard than a 5Y3, which will change both the tone and dynamics. It should be brighter and tighter-sounding.

Comparing types is somewhat complicated by some modern rectifier valves not being made to the correct original spec, but there will still be a difference between those two types.

I could tell the difference between a Sovtek GZ34 and an old GE 5AR4 by ear, when I had a friend swap them into an amp I was very familiar with - not a huge difference, but audible when you know what to listen for. That was at low-ish volume, too.