Oh, I am sorry for the obvious confusion. My bad.
I was talking about the specific KT100 labeled valves I have. The Chinese would put the name KT100 on whatever valve of higher than standard quality. I have seen ones that look like the firecrackers of the 80's and the ones that look like (and most likely are) octal EL156.
I will see if I can get a picture later.
Here are my late '90's Chinese KT-valves.
From left to right:
1. Original Chinese KT88, short bulb, triple getter, big black grid fins, round holes in anode (nicknamed firecracker)
2. Unmarked, sold as KT94, bigger rounder bulb, single getter, big black grid fins, round holes in anode
3. Valve Art KT88, bigger rounder bulb, dual getter, small black grid fins, oval holes in anode
4. Valve Art KT100, large bulb, large base, dual getter, medium grey grid fins, large black anode with big rectangular holes: EL156
There was another KT100 at the time, looking like valve 1, with the short bulb and round anode holes.
Attachments
The short stubby ones on the left. These will red plate at 25 watts of dissipation. Some will live in a 35 watt amp running on 400 volts, and some won't. The only tube I have ever seen spark out so violently that it shattered the glass in "normal operation." None of them will live at 500 volts!
I did manage to shatter a Russian 6C19pi but I plugged it into the wrong socket and forced tens of amps of heater power through the internally connected plate pins. Note a 6C19pi is NOT a direct drop in for a GE 7233 regardless of what the Ukranian seller says. It will work if you rewire the socket.
I did manage to shatter a Russian 6C19pi but I plugged it into the wrong socket and forced tens of amps of heater power through the internally connected plate pins. Note a 6C19pi is NOT a direct drop in for a GE 7233 regardless of what the Ukranian seller says. It will work if you rewire the socket.
I bought 10 X EL56 from China; all but 4 did not work and even those where way below specks. Tested them on the AVo> Cost me $A70.00 to post them back. I even paid for matching. On return all 10 where duds, did not light up for some reason the socket got very hot but the heaters did not light.
A freind of mine bought 30 Psvane KT88's they keep blowing up even in amps running at 450 volts. They blow both the cathode Resistors 10r I watt and the screen resistors. You can't use them in triode connect amps even at 400 volts. The same amps had run Sovtek Tungsols for many years without any problems.
Phil
A freind of mine bought 30 Psvane KT88's they keep blowing up even in amps running at 450 volts. They blow both the cathode Resistors 10r I watt and the screen resistors. You can't use them in triode connect amps even at 400 volts. The same amps had run Sovtek Tungsols for many years without any problems.
Phil
Hi Folks,
believe me . None of the chines fakes will work in original Telefunken applications such an ELA-V311 or V214. These old amps pumping out 100W continious service with 2x EL156 at +800V Vb / +350V Vsg.
For those who are interested , I put the schematic of the Telefunken V-214 in the attachment. Sorry for the poor quality!
The V-214 amp were developed 1959 at Telefunken Hannover by order of the German Broadcasting . They were intended to drive huge monitors (16 Ohm version) or speaker distribution lines (100V version).
The ELA-V311 is a universal allround amp, mainly used in PA or sound reenforcements system in warehouse, schools, hospitals and stations.
Schematic of the ELA-V311 here:
http://www.afrudolph.de/tfk/elav311sp.pdf
73
Wolfgang
OPT output impedance
Just curious.
the 16 Ohm amp and the 100V amp have different OPTs or they use the same OPT with a different wiring?
Thanks
Just curious.
the 16 Ohm amp and the 100V amp have different OPTs or they use the same OPT with a different wiring?
Thanks
Did you look at the datasheet?
Needs some serious capacitance to shunt the hugely voltage dependend C
in the region below 100V, or would you rather leave that region unused and topple up Ub by 100V?
Hi,
Yes both the amps got differet iron , hard beastly , loads of iron.
I owned both amps the other day, but sold them many moons ago to finance my own projects. The V311 opt. ist fixed for 100V speaker line.
The v214 opt is rewireable to archieve 8 ohm .
There must be a box with some EL156 left somewhere between my odds and ends . The only use for these valves I have is as spares for my old lab power supplies.
73
Wolfgang
Yes both the amps got differet iron , hard beastly , loads of iron.
I owned both amps the other day, but sold them many moons ago to finance my own projects. The V311 opt. ist fixed for 100V speaker line.
The v214 opt is rewireable to archieve 8 ohm .
There must be a box with some EL156 left somewhere between my odds and ends . The only use for these valves I have is as spares for my old lab power supplies.
73
Wolfgang
First time I used FETs was almost 50 years ago, and voltage modulated capacitance was really not what I needed. Nothing changed in this respect.
I still have no use for a voltage modulated capacitance or want to give up more large signal headroom than I would have too when using a tube.
As I see it, the only reason to use a follower is to get high and unaltered input impedance at the frequencies and voltage excursions of interest,
and FETs have much more limitations than tubes in this respect.
Every one has to compromise, Waveborn surely based his decisions to gain something more valuable to him.
May be he has a small signal application, I would not know on what his decision was based.
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50 years ago there was no MOS, only junction fets with a transconductance not much higher than tubes, but the voltage and temperature depending nature of this devices where a pita...and still is, it is a semiconductors characteristic that did not change much over the years...
Later on came MOS, good for logic level and some rf-applications,
I can not remember any MOS that would have been useful for any audio application other than at a few mV perhaps
Anyway, now days high gm comes at a price, high capacitance.
Would not bother me if it where mostly "static" as in tubes, or if I would have a low driving impedance to just swamp it, but hey, what would I need a follower for then?
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I have made lots of amps using 6BL7/6BX7's as cathode followers to drive Hi mu tubes like 811a's
I have considered using Mosfets, but 6BL7's work so well and saves having extra power supplies for mosfets.. Mosfets only give a slight improvement any way; I found from asking builders using them.
I have considered using Mosfets, but 6BL7's work so well and saves having extra power supplies for mosfets.. Mosfets only give a slight improvement any way; I found from asking builders using them.
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