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Tubes for Viva Solista 845 SET amp

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angeloitacare

angeloitacare

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Joined 2006
audiovoice-acoustics.com/forum/index.php
#1
hi

i have a Viva Solista SET Tube amp, and i am using standard 845 and 211 chinese Tubes.

A friend of mine recommended me to try Shuguang Tubes

http://cgi.ebay.com/Shuguang-845-84...ryZ64629QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

but someone else told me Fullmusic ones are the best :

http://cgi.ebay.com/NEW-TJ-Fullmusi...VQQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247

Is there a consistent, perceivable improvement in sound, using these tubes ? Should i change also the 211 ones, or just the 845 would give already better results ? which ones are the best ?

Angelo


http://www.audiovoice-acoustics.com/forum/
 
#2
Hi,

only my point:

- the first item is a 845C, iron plate: not carbon plate.

- the TJ, carbon plate is ok, but beware the filament current: only 0.6A instead of 3.25A for normal 845 or 211, so the filament voltage go up (11 or 12V) and the plate dissipation for the TJ is less than normal 845.

A good choice will be the Shuguang 845B, similar to old Amperex 845



http://www.tubeampdoctor.com/product_info.php?cPath=21_70_72&products_id=912

Philippe
 
#7
Each of the Shuguang/Super TnT variants have different plate material and dissipation rating amongst other audible characteristics.

In 2007 there was an overlap period where some C versions were called M by certain sellers due to the metal plates, but later, the C were discontinued and the "official" M were their replacement and had a higher dissipation capability followed later by the W.

BE AWARE !

The 845C which you purchased do not dissipate as highly as the carbon B or the metal M or W.
This may or may not be an issue in your amps, to determine whether or not they are suitable a fairly rudimentary means may be used as follows:

Be careful when you run your amps, paying close attention to the colour of the plates for the first 30 mins or so, it is easier to do this in a partially darkened room.

Observe that they do not get reddish in colour, you may note that one channel is fine but the other may become too hot and turn reddish, this is a sure sign that your amp is driving the tube/s too hard.

If the Viva allows you to adjust the bias (known as fixed bias-counter intuitively !), then you should adjust the bias down until the plates/s do not glow red at all, and set both channels to the same bias.

If your amps do not allow for adjustment of bias and you observe any redness on the plates I would strongly advise you to discontinue using them as catastrophic failure of your amp MAY occur.

The extra fins which you can see on the 845C tube (their distinguishing feature) are specifically there to provide additional dissipation due to the plate materials inherent inability to adequately dissipate to the degree required, and even so, they still do not reach beyond approximately 65% of the RCA specification.

In some cases it has been reported to me that the "wings" which are spot welded on, have actually separated from the main plate due to excessive heat build up !!!

I currently have all of the above 845 mentioned variants in stock including the KR845 which is another different design again with different heater requirements.
 
#8
hello

thanks for your ellucidating informations. I will take care and make your recommended observations. I use at the moment cheap chinese 845 tubes without any brand specification. I got them new about 15 month ago. I bought these Shuguang ones, because i start to get distortion, specially with voices, when i listen with more than 10 Watt's. Can i expect a clear sound improvement with these valves ?
Are you a dealer, and selling the Shuguang 845W's ? how much do they go for ?

thanks Angelo
 
#9
No I am not a dealer, but have accumulated supplies of many tubes for my various amps in case of price hikes and shortages such as currently experienced....

You should certainly hear a significant difference in sound quality, whether you perceive it as an improvement is entirely subjective.

I would surmise though that any NEW 845 tubes regardless of type, would sound better than knackered worn out ones 😛

Try them and let us know how it turns out, I've heard that the Viva amps are excellent sounding...which model do you have ?
 
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