Category Archives: 845-T

How is 845 like when dead?

Some forum members had a shorted tube – here is a picture of how it looks like (credit to AudiogoN member ‘amfibius’) when the event happens:

Here are some explanation from Psvane tube engineer about the event:

1. The short (lighting show you have seen) on 845 tubes is caused by residual air in the vacuum tubes act with active materials on the cathode. When active materials (electron emission coating on the cathode) become detached from the cathode under extreme heat (1000V), it will act with the residual air in the tube causing a short (lightening arc). The residual air may not be present at factory final testing when the tube leaves factory, but during shipping/handling/or usage with time, very tiny amount of air could leak into the tube, especially these large sized vacuum tubes.

2. Very few tube factory still make 845 tubes nowadays – as far as I know, only Shuguang in China and KR Audio in Europe. KR 845 tubes have quality problems too such as red plate caused by over current, so Shuguang 845 tubes have been used on most modern 845 tube amps. Shuguang made a few different design 845 tubes in the past – including a metal plate 845C. The metal plate 845C tubes were considered best sounding among all past models but the metal plate soldering cannot handle extreme heat well, so historically there have been very high percentage failure rate (nearly 50%) so the metal plate 845C tube has disappeared from the market now.

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‘far more extended at the frequency extremes’

Feedback on AudiogoN:

10-07-10: Davvie
The major difference seems to be that the Psvane is far more extended at the frequency extremes,but at the same time has a far more richer harmonic presentation. Much like the qualities of NOS 845′s

In comparison to the others, the 845T, right out of the box, seems brighter. After about 10 hours I began to notice a difference. Compared to the 845B, they seem far more transparent but at the same time much cleaner. Bass tones and pitch definition are improved. String tone seems to be more open and extended even more than the 845M,but at the same time more relaxed and natural sounding.
I always thought the metal plate 845 sounded etched and
unnatural.The 845B seemed to be a good all- round well balanced sound.

The soundstaging qualities are improved as well. Front to back layering and placement of instruments is enhanced more than likely because the sound is more open. Your definitely getting more info without any added brightness,at least once they are sufficiently broken in.

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They replaced ‘holy grail’ metal plate 845W

from AudiogoN member:

I’ve had a pair for approximately 3 months and have nothing but praise for them. They replaced “Holy Grail” metal plate 845Ws, which I don’t miss at all. Dave

original post here: http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1297442302

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‘My jaw dropped’

Posted by customer Bill D – “I received the Psvane 845 about two weeks ago. I have a Triode Corporation of Japan 845SE on the showroom floor that uses 2A3 tubes to drive the 845′s. The tubes these replaced were the Shuguang B series.
When I first fired up the amp with the Psvane 845′s in place my jaw dropped! This was now an entirely new amp. Hall sounds that I hadn’t heard before were now an integral part of the music. 3D! The sound of the stock Tri 845SE is one of the best amps that I’ve heard and now it jumped up several notches with the new tubes. And these haven’t even broken in yet.”

Original thread here: http://www.audiokarma.org/forums/showthread.php?t=318310

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