[trebejo]

I came across this reference at another audio site and I figured this would be a place to mention it.

http://www.webervst.com/ccap.html

Thanks to the warm Southern California climate I had to sell my U70 so I don't have a dog in this fight. 

[dlparker]

I came across this reference at another audio site and I figured this would be a place to mention it.

http://www.webervst.com/ccap.html

Thanks to the warm Southern California climate I had to sell my U70 so I don't have a dog in this fight. 

I love Ted and T.A.'s products. I've got four or five of their speakers and three or four copper caps, plus a few other miscellaneous products (please don't ask me to try and think..).

I'd be interested in hearing opinions from a 'hi-fi' perspective, though, because Weber's products come from a musical instrument amplification perspective, and in that sense the amplifier/speaker combination is actually part of the instrument, and 100% transparency and faithful reproduction of the sound source is often undesirable.

[trebejo]

Well Kevin Gilmore likes 'em, which is why I figured it'd be worth mentioning here.

http://www.head-case.org/forums/topic/8224-audeze-lcd-2/page__st__1480#entry486786

(Note the very lengthy length of that drifty thread, I recommend diving in around the above post).

[simon wagstaff]

Had to sell your U70??!!  Bummer.

I am not really sure but I think the most current update which included some diodes on the rectifier tube makes the choice of the tube a little less critical and extends it's life. I am not sure what the advantage would be here.

[trackball02]

trebejo, Too bad you had to sell your U70. I assume it was due to the tube generated heat. What did you get to replace the U70?

[trebejo]

trebejo, Too bad you had to sell your U70. I assume it was due to the tube generated heat. What did you get to replace the U70?

Gentlemen, please, do not mourn for me, celebrate instead that somebody else is enjoying an excellent amp. 

The replacement is the "1800R", which, indeed, generates far less heat and sounds pretty darned good.

[avahifi]

Two things:

First, a "1800R" is two Fet Valve 600R amplifiers run bridged mono!

Second, just for the hell of it I ordered a Copper Cap replacement 5AR4 solid state plug in rectifier today to try myself.

They claim their solid state module tries to replace the slow turn on and voltage drop of the tube (good) but with more durable long term use capability and steady voltage output (also good).  We shall see how well it behaves and report back herein.

Frank Van Alstine

[rlee8394]

The copper caps are OK if you treat them properly. I managed to blow a WZ68. Don't try snapping the amp back on immediately after power down. Treat the CC as a tube rectifier and it should last.

They do get quite hot. The slow turn on is around 2 seconds. They have a in-rush current limiter, CL90 I think, 10 Watt dropping resistors and a two pair of series connected 1N4007 diodes. I made a schematic of it after it blew. I have that at home. Will double check to see if I remember the config correctly.

Personally, I'd rather have a 1N4007 connected to each plate of a tube rectifier as Frank and others have done. Consider the 1000 vdc reverse breakdown voltage coupled with the 1700 vdc reverse breakdown voltage of a 5AR4/GZ34 rectifier. That's a lot of headroom. The 1N4007 diodes will even allow the use of a lower breakdown voltage rectifier since the 1N4007 adds 1000 vdc to the breakdown spec. As cheap as current 5A4/GZ34 are now, I think they provide a better alternative than the Weber Copper Cap if reverse breakdown voltage and a slow turn on greater than ten seconds are important to you.

Just my $0.02 worth.

Ron

[avahifi]

I ordered and received a Weber WZ34 Copper Top 5AR4 rectifier replacement.  It cost about $22.00.

In testing (using an Ultimate 70 power amp) I note that while a standard 5AR4 tube brings the raw DC voltage up to about 430V DC over several seconds from a cold turn on, the WZ34 comes up with about a 490V DC overshoot within a couple of seconds after turn on before settling back down to about 420V DC as the power tubes warm up.  It was then necessary to adjust bias voltage up a bit as the WX34 actually put out slightly less DC voltage than the new 5AR4 tube did.  The bias re-adjustment was not a big deal, and the voltage overshoot was within the capacity of the 500V rated first power supply capacitor.  I don't know if the initial overshoot will reduce long term capability of the power tubes though.

One thing I noted did concern me.  The WZ34 runs quite hot.  I measure about 210 degrees F near its base and at its top.  I have asked Weber if they are concerned if this heat level is an issue with long turn durablity of the part.  No answer from them yet.

The amp will go into my test system for a while as soon as I finish writing this.  I really don't expect to hear any musical differences between this and a 5AR4 tube.

Note that probably the major reason to hear any difference between rectifier tube brands is that the output voltage of them can vary as much as 50V DC depending upon the brand and the actual behavior of that particular sample.  This voltage change can change operating parameters of the amplifier enough to be audible, but what is best is a guess.  So, when you change 5AR4 tubes, it would be a good idea to note first the output voltage before and after and see if that tracks along with your opinion of a better sounding tube or not.

Regards,

Frank Van Alstine