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Which KT88??

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diyAudio Senior Member
Joined 2002
Hi,

Rich,

KT88 TESLA

You are absolutely correct.

Incidentally I did come across a few references to this tube made by Tesla Vrsovice while trawling the net.

What's scary is that I also read someone claiming the KT88 Teslovak as offered by the Pentalabs people is made in China.
The market is starting to become really very confusing...

Hmmm, just revisited the PL page for the KT88, they actually say themselves it's made in China....

I found a source that carries the real TESLA one but at Euro 90 a piece that's not exactly cheap.
The internal reference at the factory is RE 40 AK.

I actually have the datasheet in PDF format, if anyone wants a copy, e-mail me.

Cheers,;)
 
Hi Frank.......snap......Your'e quite correct RE40AK as orig tube....and yes they aren't cheap...the tubes have also scratched ID's inside on the A plate....I blow brass and use these for studio and stage work. This is the only newest made 88 variant I've used that comes (near orig) MOV spec. At 600V, it blows the chaff away from the grain.
As for manufacturers I suppose there's something to be said if the establishment has ISO9000 conformity ? The trend is gradually looking in that direction.
Certainly not from a far eastern JUNK fabrik. There's a commercial racket going on where so-called good brand tubes are be made at cheapest facilities, with scrouge wimpy QC. (quality control)caveat emptor!

I've known about the Pentalabs.......jury's out on this one...From my experience, when MOV gave up UK manufacturing GL 88's and farmed the plant out to China......the result was wimpy unreliable tubes..that's written all over..........I'm staying caged up with the Lions however, pricy they are. However Pentalabs may issue a <home-made pledge promise> ????


Viva 88's.
 
I bought these valve from ebay, seller is American.
Can anyone tell me these one are fake or real one? What is different between Tesla and Teslovak name?
Tks
 

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:D! Tks for answer.
I found this information
SLOVAKIA, CZECH REPUBLICS:

Teslovak, Cadca:
Spinoff from now-defunct state factory Tesla. Currently
the major source for Groove Tubes. Teslovak tubes are
often sold under the Tesla brand name.
I compared it with Gold lion, the structure is little better
 
"I've been to Czechoslovakia, and I've toured the tube factories. I even have friends and relatives who work there. Maybe you'll find this interesting:

TESLA was the state-owned tube manufacturing facility in Czechoslovakia while it was under Communist rule. The TESLA plants have been in continuous production of vaccuum tubes for the Com Bloc military since the time that they were first built. Even today, much of the radio comm gear in the Central and Eastern european nations is vacuum tube based, and vacuum tube manufacturing has never slowed down. (Even some MIG fighters still have vacuum tubes in them).

When the Russians left, Czechoslovakia continued to produce TESLA-PRAGUE branded tubes at their plants in the states of Bohemia and Moravia (which would later become the Czech Republic) and in the state of Slovakia (which would later become the Slovak Republic).

Both the Czech and Slovak factories had always been TESLA plants, and tubes carrying the TESLA PRAGUE name were actually made in either the Czech or Slovak plant. The company didn't distinquish between them.

Czechoslovaka was a country comprised of three states: Bohemia, Moravia, and Slovakia. When the state of Slovakia seceeded from the States of Bohemia and Moravia in 1991, the secession went very smoothly and became known as the "Velvet Divorce. Czechoslovakia split up into the Czech Replubic (Bohemia and Moravia) and the Slovak Republic (Slovakia).

The Czechoslovak state-owned manufacturing facilities were similarly split up, with the TESLA factories in Bohemia/Moravia becoming the property of the Czech Republic, and the factories in Slovakia becoming the property of the Slovak Republic.

Following the Velvet Divorce, things became a bit confusing for us Westerners, as TESLA was now a company that had been split in two, and two different nations each had factories producing tubes witht he TESLA name on them. For this reason, the Czech tubes continued to be branded TESLA PRAGUE, and the Slovak tubes were branded TESLA Slovakia.

Here in the West things seemed pretty complicated - people who couldn't even spell Czechoslovakia had no idea where the tubes were coming from -- two different companies were now calling themselves TESLA, and both companies were in fact halves of the original company which had been split-up. Each continued to make the same products that it had always made, in the same plants, on the same lines, operated by the same employees. Teslovak later changed its name to JJ when private investors bought the company from the Slovak Republic's government, thereby eliminating some of the "Who is Tesla?" confusion. Unfortunately because of this alot of people fail to realize that JJ tubes are actually TESLA Slovakia products.

So which ones are real Teslas? Both TESLA Prague and JJ/Teslovak are manufacturing the same tubes that they always have in the original Tesla plants. Although the tubes now bear a different trademark, NOTHING else has changed. For all practical purposes, there are two "flavors" of TESLA tubes today, and both are made by the same people who've always made them. "
collecting from Re: Why isn't there a tube manufacturer in the USA ? - AMPAGE Archive
 
The real point on my updated Cary SLM100 (Mono blocks originally each with 4 KT88) was the following:

- Each brand sounded different also in conjunct with different driver tubes :D

- best (for my ears) the EE, this means may always a question on used materials within the tube

- Now I am running on Cyro Treated KT120 as from Gold Lion KT88 Cryo Treated Matched Quad- Cryoset Online Store- Genalex what REALLY produced a much lower idle noise and more punch as the KT88 from EE :D (had to replace the transformer to deliver the required heating current)

just my 2 cents

Hp
 
Good day from Greece! I like tuberolling ,and i test in my diy SEP amplifier,many KT88,6550,and KT120 tubes. The bias is hot 370Va-k, Ik about 100-113mA, in these condition i take the best sound, i do not care for the long life of tubes. The results is very interesting. In first time,i use shuguang 6550A-98,cheap tubes from ebay,very good sound,and very stable plate current 110mA each,well matched.I used from six months,everday,the only problem which i have is little redplating,and the micas turns in black colour,and the bottle turn in brown colour.like mullard tubes,best tube for the buck. After i buy guiguang KT88,for cheap,same sound as 6550,but after a month one tube dead(thermal runaway). I buy tubes only from ebay,no problems if you buy from good sellers. The last chinese tube which test is Shuguang KT88-98A, no problem with these tubes,no problems at all no redplate,but the sound is same in all chinese tubes. Other tubes which i test is JJ KT88 ,and TUNG-SOL KT120 reissue. The slovakian JJ tubes is very different animal,very strong build,no problem,in high plate current,looks like lasts for ever,but i do not like the sound too many bass and mids is not my taste. The new sensor KT120,at last,the sound is an another class,never hear my system plays like that,but the QC is not the better,the getters fade pretty fast,and one tube tends to increase plate current,about 4mA, in a 2 months of use,now i use the second pair of KT120,but i have a strange problem in one tube When tube start to conduct the plate current is about 103ma,the same in the other tube,in a few minutes,the current rise down about 95ma,stay here for a few minutes and rises again to 103ma,and stay here,with out any variation,no problem when the tube gets warm. I change the tubes and the problem follow the tube,the tubes is perfect matched about 0.2 ma between them! Thats my 2 cent!
 
G...and TUNG-SOL KT120 reissue.
Once again, there is no TUNG-SOL KT120 reissue. In fact Tung-Solnever made a KT anything. Once again, the KT brand was owned by Genelec (aka MOV) in the UK, and the last kinkless tetrode they manufactured was the KT88.

Any "KT90", "KT100", "KT120", etc valves you come across are simply communist bloc military/transmitter tubes that have been given a fake KT label for marketing purposes. Adding the Tung Sol name is even more of a grand deception, which ends up confusing even more people.

Having said that, they probably do still sound fine when biased correctly
 
Tung-Sol 6550 Reissue is what I use, no problem, I find them even better than KT-120s

The bottom point of that tube rolling is to do a THD test, best to confirm both by ear and by THD analysis.
Good afternoon from Greece! I have a question,for gabdx,or other who test it or use it 6550 Tungsol reissue. These tubes are robust to use in SE amplifier, hot bias about 100 ma 370Va-k,without problems? Anyone to suggest me other brands KT88,or 6550,with good sound and good power handling? I know the tube buy is difficult these days. The NOS tubes is too expensive for me!
 
Good afternoon from Greece! I have a question,for gabdx,or other who test it or use it 6550 Tungsol reissue. These tubes are robust to use in SE amplifier, hot bias about 100 ma 370Va-k,without problems? Anyone to suggest me other brands KT88,or 6550,with good sound and good power handling? I know the tube buy is difficult these days. The NOS tubes is too expensive for me!
As EU citizen JJ KT88 is a clear option, both for prize and quality.
 
As EU citizen JJ KT88 is a clear option, both for prize and quality.
Thank you for your suggestion! I use JJ KT88 very good tubes,built like a tank,no problems at all,no redplate stable bias but,i do not like the sound,i like the bass,but the mids it is too much for my taste, and the highs are dry,not balanced sound in my system.The chinese tubes play much better,but is fragile and stressed in these conditions. I tested 6550a-98,and KT88-98,but i am afraid to use it,in continuous mode.The KT120,is the no1 for me, at this time,unstable bias,in first 5 minutes,but after it is stable like a rock Good afternoon from Greece!
 
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