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Old 26th March 2010, 02:16 AM   #1
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Default Kt-120 ?

Anybody know anything about the Tung-Sol KT-120 ? New design.Plug in for KT-88.
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Old 26th March 2010, 03:32 AM   #2
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Bob Latino posted some info on the Tubes Asylum today.

New Tungsol KT120

Jeff
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Old 26th March 2010, 05:56 AM   #3
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I'm still waiting for this one:
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Old 28th March 2010, 06:36 PM   #4
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Yes, I've spotted it too. For fixed bias, the spec suggests 51K grid leak at the spec voltages shown. The 29pF input capacitance requires a current dump for best performance. Both are nasty. For lowest distortion, only the best low Z driver stages can deal with them. For autobias, it's another picture. Does ones design warrrant such a beast ? Maybe New Sensors experience with the EH KT90 (I get excellent results with this in UL 40%, better performance than any 88's) have now come up with the trump meister.

richy
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Old 28th March 2010, 06:44 PM   #5
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Quote:
Originally Posted by stonedeaf View Post
Anybody know anything about the Tung-Sol KT-120 ? New design.Plug in for KT-88.

NOT plug in for KT88/6550. Heater current draw is greater and the tube biases very differently. The 51 KOhm grid to ground max. will make for big trouble in most amps that employ "fixed" bias.
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Old 28th March 2010, 06:54 PM   #6
Trout is offline Trout  United States
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I do not know about you guys, but I see this as a white elephant!

Lots of chatter over on the guitar amp forums as well, but think about it really.

Who would design an amp around a single source tube given the spotty reputations ALL current production tube manufactures have.

Now if SED, JJ and New Sensor and maybe others were all making the same tube it might not be a bad idea, but single source? Not likely.
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Old 28th March 2010, 07:18 PM   #7
kevinkr is offline kevinkr  United States
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This is probably the most reliable single source currently extant for tube manufacture. (Tightly run and well managed) Should there be sufficient demand someone else will probably clone it.

I can guarantee that if no one buys it because it is single source there will be no incentive for anyone to introduce anything new. Remember when the EI KT-90 was single source, that vendor is now gone, and guess who makes it now? A lot of you guys are using the original and the EH clone.. (The same parent company and plant as is making the KT-120. hmmm...)

The people who will probably buy it are those who have always purchased the currently available production: companies like Conrad Johnson, ARC, Quick Silver, Manley, and VTL who currently manufacture big PP tube amps. Throw in a few guitar amplifier manufacturers and you get the picture. These guys aren't buying NOS tubes from some secret stash somewhere. I imagine the appeal will be even higher power PP amps with lower tube counts keeping manufacturing costs down.

I plan to purchase a few for use in a high voltage, high current series pass regulator.
(pentode connected) For my application it looks ideal and I will purchase enough of them to meet my needs for some time. (Not too many)

Given that every tube made today - even the EL34 suffers from some level of inconsistency of performance with some vendors clearly making better sounding/more reliable versions than others one could almost argue that a lot of these tubes are effectively single source if you happen to have a particular favorite.

Almost none of my favorites are currently made - so I have stock piled a sufficient quantity to keep me going indefinitely. With a little planning, some luck, and a reasonable budget it is possible to do that with any type that has not yet achieved cult status.

What I am saying is if the tube interests you buy a few, and perhaps more interesting types will subsequently follow.

Expo-Pul, New Sensor's Russian plant probably makes more tubes than anyone else and is responsible for the following brands: Sovtek, EH, Mullard (reissues), Tungsol, Svetlana from the old SED joint venture (Not to be confused with the now separate Svetlana SPB) and probably a few I have missed. IIRC Over 800 employees working in this plant have got to make it just about the largest remaining tube manufacturing operation.

Nay saying is so fashionable these days..
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Last edited by kevinkr; 28th March 2010 at 07:37 PM.
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Old 28th March 2010, 07:31 PM   #8
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Kevin,

Properly made EI KT90s are a joy. The EH version, with its flat sound stage, is a disappointment.

FWIW, I'd rather that New Sensor restarted production of 7199s and 12BY7s, types for which a clear need exits, instead of introducing a power O/P type of dubious merit. NS has already done well by resuming 12AY7 and EF86 production. I wish they would do more, along those lines.

With a few circuit tweaks, maybe the KT120 can be useful in the Fender bass guitar amp that works well with GE 6550A "finals".
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Old 28th March 2010, 07:44 PM   #9
kevinkr is offline kevinkr  United States
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Quote:
Originally Posted by Eli Duttman View Post
Kevin,

Properly made EI KT90s are a joy. The EH version, with its flat sound stage, is a disappointment.

FWIW, I'd rather that New Sensor restarted production of 7199s and 12BY7s, types for which a clear need exits, instead of introducing a power O/P type of dubious merit. NS has already done well by resuming 12AY7 and EF86 production. I wish they would do more, along those lines.

With a few circuit tweaks, maybe the KT120 can be useful in the Fender bass guitar amp that works well with GE 6550A "finals".
Hi Eli,
I remember the early exploding EI KT-90 rather well, and the later ones with serious linearity issues, and I remember some that performed quite gloriously in the modified Citation II's I was responsible for.. I haven't tried the EH KT-90 so I can't say anything about their merit or lack thereof..

I agree with your comments about the 7199 and 12BY7A - would definitely be worth their while to make good ones.

Are you sure that the KT-120 is not the result of demand for a higher power KT series tube, and that in fact someone did not ask for this tube? I guess we will have to wait and see where it appears first. Mike Matthews is nothing if not an astute business man...

I can see an immediate use for it in some power supplies I am designing for my next SE amplifier.. A KT-88 would be running at the limit of its dissipation in my application, the KT-120 gives me some margin.
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Old 28th March 2010, 11:09 PM   #10
Trout is offline Trout  United States
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Quote:
This is probably the most reliable single source currently extant for tube manufacture. (Tightly run and well managed) Should there be sufficient demand someone else will probably clone it.

Agreed up till reliable, since that has not been my previous experience with new sensor tubes in general the past 3 years.

I have thrown away more bad tubes from them than from JJ or SED (new fresh from the box)
My out of the box bad percentage has been horrid enough that I rarely buy them now, so I do not know exactly how they are now.
I did throw away 6 more new 12AY7's last month, 6 out of 10 bad? PASS for now TYVM
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