Tube vs Solid State Rectifier for VTA ST-120

deepee99 wrote:

Bob Latino wrote:

Dogstar wrote:

I bought two WZ68’s before the WS1 was available. I’m still using the first one. What are the problems with using the wz68?

There are no problems with using the Weber WZ68 in any of the VTA amps BUT > For some reason the Weber web site gives some warning about using the WZ68 in "audio" amps ? I honestly do not know why they have that little blurb about not using the WZ68 in audio amps ?

Bob

I think it was the late Kentley (RIP) who noticed this fine print swap-out on the WZ-68 originally. I figured some lawyer knew something we didn't. If memory serves, it had to do with home hi-fi being more demanding of the rectifier than a guitar amp. Again, heat's the devil with the WZ-68. When my last GZ-33 takes its final gasp, I'll probably just sub it with a WS-1 and TDR fix-up.

I have 2 GZ-33 and 3 GZ-37 in my stash,which I have had for years in reserve, they'll probably out live me.

Hops wrote:Perhaps it is all the complaints about the heat of the WZ-68,  and advice the drill holes in the copper cap in response, that has Weber wary.   I bought a WZ68, a WS1 with thermistor,  and a Tung-Sol  5AR4.   The WZ68 is in the (newish) VTA-120 and is working well ( no holes drilled).   If it fails,  I will try the Tung-Sol,  see if it sounds different,  and if it fails try the WS-1.  So far the WZ68 is working, the Amp sounds good.   I run 113-118 V through a Variac ( target 115 ) with a TDR.

I believe original Dynacos were wound with a 115-VAC input tap; whereas Bob's are wound for 120 VAC, which I would use as the reference voltage for bias checks.
In defense of the WZ-68, when I was going through them once a month I had a very difficult speaker load that worked out to about 2 ohms. That may have contributed to my heat issues.

Hops wrote:Perhaps it is all the complaints about the heat of the WZ-68,  and advice the drill holes in the copper cap in response, that has Weber wary.   I bought a WZ68, a WS1 with thermistor,  and a Tung-Sol  5AR4.   The WZ68 is in the (newish) VTA-120 and is working well ( no holes drilled).   If it fails,  I will try the Tung-Sol,  see if it sounds different,  and if it fails try the WS-1.  So far the WZ68 is working, the Amp sounds good.   I run 113-118 V through a Variac ( target 115 ) with a TDR.

If you're going the new tube route, you might give Jim McShane's new-issue Tung Sol and Gold Lion 5AR4s would be the best in that line,IMHO.

Bob Latino wrote:

Dogstar wrote:

I bought two WZ68’s before the WS1 was available. I’m still using the first one. What are the problems with using the wz68?

There are no problems with using the Weber WZ68 in any of the VTA amps BUT > For some reason the Weber web site gives some warning about using the WZ68 in "audio" amps ? I honestly do not know why they have that little blurb about not using the WZ68 in audio amps ?

Bob

My guess is it is all about the sag.

Weber includes a dropping resistor in the WZ68 specifically to emulate the current based voltage drop one would see with an actual tube. They are probably assuming HiFi amps would not want this sag, and hence their recommendation for guitar amps only.

But those who prefer the sound of tube rectification in HiFi power amps might like the sag, and maybe should get the WZ68 to maintain the same sound.

I can't think of any other possible reason they would not recommend it for HiFi.

Dave, (all) recently talked to Jim cause I lost another 5AR4, he does not carry 33 or 37 tubes. He did, however highly recommend the GZ34 which I ordered. Running it now. Dale