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EQUIPMENT FORUMS >> SE84UFO25 >> the reading on the meter
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Message started by sz66panzer on 03/07/23 at 13:12:34

Title: the reading on the meter
Post by sz66panzer on 03/07/23 at 13:12:34

When I just received my SE84UFO25, I noticed that the meter read about 32 with the 6P15P sent along with the amp. As written in the manual 'With the supplied output tubes, the meters should read between 20 and 30 mA. Tubes that fall outside that range should be watched carefully. 'So I think the tubes are already in an unhealthy state.

But these two days I have in succession received some 6P15P and EL84s, some are brand new and some are NOS.None of these tubes read below 32 on the meter,the EL84s are even higher about 36.Unlikely all these tubes are unhealthy, so I wondered if the manual be correct here,or if my meter have some problem,or ..
Could somebody help to explain ?Thanks in advance. What's the reading on your meter?

Title: Re: the reading on the meter
Post by Lon on 03/07/23 at 13:16:34

My new tubes bought from Steve or eBay or the one pair of output tubes bought from Wathen all read between 30 and 40 on my Taboo Mk IV when brand new (the only component I have with meters).

I think that the wording of the manual could be better in that it is not an issue if the tubes read ABOVE 32 but that if the tubes read on the meter below 25 to 32. So . . . in my opinion, based on 25 plus years with these output tubes in Zen amps. . . rest easy, your tubes are fine, more than fine. Use them with confidence and enjoy the music.

I don't believe Steve feels differently, if he does I hope he chimes in.

Title: Re: the reading on the meter
Post by sz66panzer on 03/08/23 at 01:02:45

Thank you Lon! Very helpful!I wiill ignore the meter reading ;)

Title: Re: the reading on the meter
Post by JOMAN on 03/08/23 at 19:55:06

Second what Lon said and will add the following...

Speak with Steve if you would like further reassurance. I doubt that there's anything wrong with the meters. Note that in the instructions the word "should" is used not "must". My conversation with Steve about this was quite some time ago so I can't be specific but I believe he also mentioned that the incoming power could be a factor.

I have found the meters to be very useful in the following ways:

1. Checking how closely the tubes are matched

2. Indicators of the amp reaching its limits, the meters will "dance". I've yet to have that happen and I have pushed it, hard!

The manual states that the UFO25 is a very transparent amp and that you could notice artifacts/distortion as a result. I've only recently discovered just how transparent it is. Absolutely outstanding! If you should hear artifacts/distortion the question then becomes, Is it the result of the amp at its power limits or is it something else??? Easy way to tell is to look at the meters. If they're steady then the amp is not at its limits. It's something else. I've found this to be very useful.

Title: Re: the reading on the meter
Post by Bilyeaux on 03/09/23 at 00:34:07

Thats exactly where mine have read since receiving my UFO2.1 about 17 months now. Same with back up tube set, all good!

Title: Re: the reading on the meter
Post by jec3504 on 03/09/23 at 02:02:47

Using different types of rectifiers change the reading? Just curious if that had an effect on the UFO2*.

Title: Re: the reading on the meter
Post by Tony on 01/20/24 at 18:50:09

I was reading some posts from early in 2023 (it's a slow morning here in Berkeley:) and found one that still leaves me scratching my head. JOMAN said back then:

"I have found the meters to be very useful in the following ways:

1. Checking how closely the tubes are matched

2. Indicators of the amp reaching its limits, the meters will "dance". I've yet to have that happen and I have pushed it, hard!"

#2 IS OK, but #1 I'm still not following? Which tubes does he refer?

Out of the seven tubes in this amp, four are in pairs: the 6P15P and the OA3. Are the values on the meters revealing the potential matching of the first pair or second pair of tubes.

Maybe I do not appreciate the value of these meters, their overall contribution seems minor.

Thanks

Title: Re: the reading on the meter
Post by CAJames on 01/20/24 at 21:18:34

Quote:

Posted by: Tony Posted on: Today at 10:50:09

...Out of the seven tubes in this amp, four are in pairs: the 6P15P and the OA3. Are the values on the meters revealing the potential matching of the first pair or second pair of tubes...

The 6P15P, i.e. the power tubes. The meters read the current "out" of the power tube into the output transformer, which you can think of as the current "carrying" the music on each channel. They ought to be, if not exactly the same, then pretty close.

P.S. I guess if there were problems with OA3 aka VR tubes that would show up on the meter as well. Although I think in general either the VR tubes work or they don't, they don't get weak. You would also see that as the tube getting dim.