Which EL34 tubes for Hi Fi

[richwalters]

Tubesteve quite right.
Like all second source stuff, my first instinct is to electrically hammer them with the Mullard as my reference. The others hold up equally to the Mullard. There is a new issue EL34 Mullard being made by the Russians. SOme institution has bought the Mullard logo.....is this Reflektor, or who ? and has anyone electrically hammered these ?

richy

[tubesteve]

the new sensor corporation , new york, bought recently: Tung-sol, Mullard etc. names. the man behind is Mike Matthews, he operates the EH/ sovtek factories with a link to svetlana fty. for me the re-issued mullards are the same as the Svetlanas as far as i can see the construction ( EL34 ). maybe they select just for different performancesand then label them..... its all about marketing. you make take that mullard el34 as good, seems to be an XF4 from the last production done.

the dimple top RFT EL34 tubes have been used in man guitar amps with no problems.the only issue is el34 dont like much more G2 voltage than 425V, despite what the manufacturer states. remember: tubes are mechanically constructed according to drawings which should be identical in dimensions.
there is not much room to change, besides the vacuum and the materials and workmanship.

i have measured quite some different EL34, the differences in curves are marginal. they react but different on higher plate voltages.

the closest construction or identical to NOS is nowadays from JJ using old tooling resp. repaired or re-newed it. but they seem to have a few quality issues.

[tubesteve]

there is one more thing to say about new production: after observing the Shuguang factory here, it seems, the chinese learned, to improve their tubes.
after manufacturing firecrackers in glass housing for decades they got more knowledge and help from abroad to make thingss better. as this continues, they will understand, this can earn money by relaibility and quality. Some of their tubes are really good, as for example the KT66 and the newer EL34B edition. their small signal tubes perform well, but i am still concerned about their life time.
their factory now looks more clean and organized, than 5 years ago. They have to do for the names on their place: LG and Philips logo is on them

[richwalters]

The EL34 branding seems to be better controlled than the choatic 6550 versions. SOme are downright dreadful performers. It does surprise me how versatile the EL34's are to being punished, the anode dissip ratings holding up better than other power tubes of the same power class..How the many different versions hold up on actual distortion and loading conditions is another question. This is an area I am interested in.
The 6550WE now an obsolete clear glass + pellet getter, is really a hopeless power performer, and yet it is the only 6550 version (apart from the orig NOS A GE series) which gives very low distortion. A pity that over 30W, the WE power handling ability crumbles.
A bit more expensive, my choice option for poke, is go for the EH KT90 (and not KT88). (another thread).This straight pencil tube amazed me beyond expectations. There are caveats; not all types of output transformer relationships for a given A-A impedance are a perfect match for all tubes as per quoted spec claims.
I've lost track if the EH KT90 is a real pentode modified from the line sweep TV version or if it is a beam tetrode. To me the new version looks like the latter.

richy


richy

[tubesteve]

normally the KT90 should be a beam tetrode as the "K" tells you. it was "invented" by the Ei company from aTV tube to be an audio tube. and its not very linear. some of the KT88 or 6550 are the same, either penthodes or tetrodes bcc. same rating. RFT for example rated the EL34 as KT77 bcc. same or similar ratings. rebranding, renaming is a big business, iven if its not the accurate same thing. note: the KT77 was designed for higher G2 voltages in UL operation.
nowadays, they are so nice, to tell us, that a 2CX250 or so is an audio tube, which is in fact an RF power tube ( Svetlana ), seems, they wanna get rid of old stuff or, wanna foolish people. these tubes are not nice linear for audio, producing lots of harmonics, which were removed in RF low pass filters. making money is everything!
the 6550 is the answer to the KT88: pentode against beam tetrode. both have bee developed for public address ( VOLUME!! ) but not for hifi. same applies for EL84, cheap and loud enough for home radios. it was never claimed to be HiFi, at least in SE configuration. but i must say: some distortion adds to the sound, even order... why most manufacturers publish THD and never intermodulation? bcc.: its so bad. who is listening to one signal ( 1KHz) only? me not.

[Tomasz Rodak]

this is the reply I have just received from JJ Electronic


"we have never printed JJ tubes with another brand."

Best regards,
Julia Jurcova
sales

JJ Electronic
A. HLinku 4
ZIP: 022 01
Cadca, Slovak Republic
tel.: +421 41 4304 120
fax.: +421 41 4335 370
info@jj-electronic.com
JJ-Electronic - Vacuum tubes, Capacitors, Amplifiers - Home

[tubesteve]

i believe her. JJ never tried to do this. it would be to be to obvious. JJ is a family business. good. there are sharks out there,

[Panicos K]

Originally Posted by Tomasz Rodak

this is the reply I have just received from JJ Electronic


"we have never printed JJ tubes with another brand."

Best regards,
Julia Jurcova
sales

JJ Electronic
A. HLinku 4
ZIP: 022 01
Cadca, Slovak Republic
tel.: +421 41 4304 120
fax.: +421 41 4335 370
info@jj-electronic.com
JJ-Electronic - Vacuum tubes, Capacitors, Amplifiers - Home

Which obviously points towards older Tesla sourced tubes,not a bad thing afterall.