On Aug 17, 12:37*am, charles rollo charles.rollo.
wrote:
Recently my amps trannies were melted when the 211 failed. With less
than 150 hours on the tube but past the 30 day warrantee.
I bought the tubes in Oct. 2009 from Grant Fidelity. however never
used them until well after the 30 day time frame. Which Grant was aware
of.
One tube shorted and took out the output and high voltage trannies.
Costing me $1500 to repair.
Neither Grant Fidelity nor Full Music will care after the 30 days
expires. For $500 one would think that the Manf. or north American
distributor would make ammends because of the damage done. Something
fishy going on as the distributor.
No no and no is the answer from them. Buyer beware. Stay away.
charles
--
charles rollo
Your 211 tubes would appear to be made at Tianjin, China, who also
make 845 tubes.
I had a customer here who had bought a pair of Ming-Da monoblocs which
require a pair of 845 per channel. One of the existing 845 which came
with the amps was an old Shuguang type 845C in which the welding from
wire to anode inside the tube had broken. This caused the PP output
circuit to operate with only one tube and the sound was bad and this
tube overheated. Luckily no transformers were damaged. One could
always have a tube with a bad weld which was not spotted during
quality control and which took 200 hours before it fatigued and broke.
One could see the weld was dodgy when comparing the tube to others.
Anyway, the owner bought a quad of Tianjin 845, and they just didn't
work and they just caused fuses to blow.
He brings his Chinese Horror Quality amps to me and I completely
rewire them so they won't blow up nor sustain damage from failing
tubes and so he can easily set the bias.
I tried the TJ tubes after my mods and they all arced over internally,
so I built a test circuit so I coulod examine each 845 more fully, and
even with only 1,100Vdc at ther anodes, they still arced over.
My client returned the TJ 845 from where he purchased them, with
copies of emails between myself and himself.
My customer bought Shuguang typeB latest good quality and has had no
troubles now after 12 months.
Despite seeing an example of one bad weld in an old Shuguang, the
Shuguang internal build quality is generally FAR SUPERIOR to the over-
priced crap coming from the TJ factory.
So it comes as no surprise that you are having bothers with the TJ
211, and as you may know the 211 and 845 have very similar internal
construction and it is conceivable that what is drastically wrong with
a TJ845, may also be wrong with 211, ie, the tube has a built in fire
cracker nobody wants.
Of course we must ask what kind of protection circuirts does your
amplifer have to prevent mis-behaving output tubes from damaging OPTs
and PTs? Only a complete fool would allow himself to own a tube amp
with 211 or 845 within and without any form of adequate active
protection measures. Of course ppl who enjoy the wonderful way such
tubes deliver music when they do work properly do not consciously try
to be fools, and they do so rather unintentionally because they just
see the bright up side of the purchase and none of the down side and
possible disasters awaiting them because the manufacturers of both the
amplifiers and the tubes don't want anyone to realise there could be
problems. Does it not occur to you that a 30 day warranty is rather a
crummy warranty which implies, "Watch out - possible Fire Cracker
within".
When I built a air of mono blocs using 845, I put in the active
protections to prevent excessive anode current from causing smoke. See
my page abd read carefully...
http://www.turneraudio.com.au/monobloc845se55.html
I am one of the only tube amp manufacturers who includes active
protection against bias failures and against runaway anode current.
Much of my work over the last 15 years has been to make tube amps
smoke free and to give them singing lessons with soldering iron and
long nose pliers. Many good brand name amps have been on my bench,
ARC, Quad, Leak, Manley Labs, Dynaco, VTL, and many others from China
which I cannot say are good brandnames.
Today, the range of products forsale is utterly mind boggling, and
sellers can have real bothers if they are responsible for the failures
of things they sell but don't make. Here in Oz, a dealer or store is
legally responsible for product failures prior to warranty expiry. But
we have cases where stores tell customers to take the product back to
the maker; they don't like having to replace an item or act on behalf
of a customer and get a replacement from a maker. There are forces
ranged against the Bloke in the Street who buys something at a shop.
Just be aware of your rights, and the terms of the trading and about
what happens if things malfunction. Most ppl are not the slightest bit
technically minded and they just don't know what questions to ask
about the tube operated product they are buying; they are often
naively stunned by the very low initial price - courtesy of the slave
labour in China working for less than 1/20 of your wage.
BTW, had you managed to buy KR audio 211 for your amps the purchase
price may have been +15dB more than the Shuguang price. But whether
the KR tube is better sounding or not is anyone's guess. But KR have a
1 year+ warranty.
The KR 845 tube is the best looking 845 I have ever seen - definately
the work of dedicated old European master craftsmen as opposed to the
trained monkeys working for a pittance in China. HOWEVER, the KR tubes
have oxide coated directly heated dull emitter cathodes rather like
the 300B and one suspects the cathodes may not have as long a life at
Ea = 1,000Vdc as would the bright emitter tungsten cathodes of old RCA
845 AND the Shuguang types. My opinion is that the KR tubes might
suffer from positive ion bombardment and erosion rather too early in
the tube's life compared to the thoriated tungsten cathode which is
virtually imune to such bombardment. The ion bombardment only becomes
a problem when anode voltages become higher than around 800V because
the voltage difference determines the ion speed of travel and the
higher the speed, the greater the damage. If this were not tru then
all HV tubes would have the easier cheaper more efficient dull emitter
type of cathodes, or indirectly heater cathodes with oxide coatings.
I hope you learn to be more wary in future. So don't be too ****ed off
with your troubles; you could have spent more and got less
satisfaction in any number of ways. I was once married to Marilyn
Munroe, and boy, she cost so much to run and things went wrong all the
time.
Patrick Turner.