Tung Sol

[butwhatif]

Anyone try the new Tung Sol KT120, or KT150 tubes in a build yet---looks to be a formidable tube---

[Satchmoeddie-II]

The 120s are okay, but stay within the KT88 voltages. They are pretty clean, lots of good headroom, but they do not have the real KT88 Genalex Marconi Osram Valve sound. It almost has a touch of 6L6 & 6550 sound in it. Try a pair in a 75-120 watt amp, and see. I think you will find some sounds you like. AR is using the KT120 now. I miss the old EI KT90s. For the money try a pair. They are different than the other KT88/KT90 stuff, & the 6550s. It is a good different, in my opinion. Now onto the KT150. I received a batch of "ringers" that had been preselected for me to evaluate. It looked as if they had been on an aging rack for a while too. They tested very well. Later I got a case of random new KT150s and tried to run them at 800 volts plate. Right out of the box, most failed after an hour. Some barely lasted 10 minutes. Aging them did help. I put them in sockets hooked the heaters up to a Variac and dialed it up to 9.5 volts & let them bake for a day. This helped quite a bit. I would say try the KT120s, and leave the 150s for Hi Fi guys to play with. The KT150s cooked a $3000 Nobatron PSU for me, so I am not too happy with a tube that fried a power supply. The 120s are close enough to a KT88 electrically they work fine in place of a KT88. The KT150's plate resistance is not as close to that of a KT88 or 6550, or another tube NOS tube I dearly love but keep to myself. If New Sensor is so innovative, why are they using Mullard, Genalex, & Tung Sol brand names? JJ just bought the rights to Telefunken, and are making all kinds of stuff Telefunken NEVER made & putting the diamond logo on it. I run a modified Tektronix 576 curve tracer, a modified Triplett 3444 with regulated voltages, & use them with Fluke bench meters. I also have an ESI LCR that will give internal element to element capacitances, resistances, impedance, & a plethora of tests. The curve tracer was modified to test tubes, as it is a high powered transistor curve tracer. Add heater voltage, and screen grid voltage supplies, set your voltages and any tube tests as a Field Effect Transistor, and give factory spec curve plots for vacuum tubes. FETs & amps tubes test the same way. You get a Gmohs, Ip, Ep, pretty much all the plots in the RCA books. I found New Sensor's claims that you can up the plate voltage, change the plate to plate Z in the OT and get 150 watts per pair highly exaggerated, so use it as a KT88, & let the audiophool hi fi guys try to milk 150 watts a pair out of these. They can afford to blow up more stuff than I can.

[JD0x0]

I've got a pair of 88's in an amp that was originally designed for 6L6's/EL34, with no mods, they sound pretty good IMO. I've been tempted to try a pair of KT120's but I know I'll likely need to do some mods to get the voltage up. As it stands, I think my heater current is a little low for the 88's and the plates are a bit low, since the amp is unmodified in the power section, but to this date, I haven't had any problems running Chinese KT88's in the amp and they sound great. Big, open, and balanced, with tons of headroom. Because of this I'm tempted to try the KT120's and simply up the bias a bit, I know this is extremely lazy, but I'm not sure if I want to mod an amp that functions perfectly with 5881's, 6L6's, KT77's and KT88's, just to see what the KT120's sound like. Adjusting the bias is easy, so I might just do it for poops and giggles.