The datasheet states 100 watts from 1 pair of KT88. They do not "break a sweat" at that level. You can even get 150W for speech/modulator service (Class B triode). Even a pair of EL34 will make 100W. You can get 200W from KT150.
This is very true. Much less money, too. I have a feeling it's the egg shaped bulb that attracts the client.
I saw this on another thread on this site forgot to book mark it
KT120-KT-150
Hello, I am running SE-monos with KT150@50W anode dissipation. What I do see is a dull red glow of the anode in the pin 1 area, the attached picture shows it quite nicely. I do own 4 KT150s, they all show the same behaviour, in both amps. KT120s with the same dissipation settings, however, do not show any signs of anode glow. Did anybody owning KT150s notice a similar behaviour? Would not really like to challenge mine with the rated anode dissipation of 70W.... Thought I bought them from a reliable source, do who knows ? Or this is a KT150 feature, not a failure - they accumulated at least ~150h so far quite happily... Any hint is very much appreciated!
Marcus
Attached Thumbnails
Has anybody wondered why the manufacturer has not published reasonable specifications ?
These are not sufficient at all: http://www.newsensor.com/pdf/tungsol/kt150-tungsol.pdf
Hi All,
Yes, as Bruce says I had four KT120s that showed red at 60 watts total dissipation right out the box. I then returned these and swapped them for 8 x KT150s and of these:
-4 work with no red showing but of these two have quite deformed glass bulbs
-4 were defective. 2 of these showed red, while of the other pair, one made loud cracking noises out the box and both valves in that pair could not be balanced for dissipation.
So quality is a serious issue with these Russian tubes. I have had similar problems with Electro Harmonix and Sovtek output tubes too. Strangely enough I have had no problem with their small signal tubes.
I will continue to get these tubes from a sympathetic dealer who replaces them and credits return postage if there's any problem until I get satisfactory tubes.
David
Hi all,
seems that indeed the manufacturing quality is not entirely stable. Would also guess that missalignment might be the issue. If I change my KT150s for KT120s with the exact same settings (460V/110mA) there is no indication of any red plating..might be unlucky with my 150s, but lucky with my 120s
Marcus
supposedly Shuguang makes KT120's.
Treasure KT120-Z CB @ $262.00 per pair.
Not ready to jump on that boat just yet.
Stu
Hi, To add to the fury.... A licensee in the UK of some of our company's designs has reported the same thing. The tubes are used in push-pull with a CCS and are well within spec. Red anode stripes and glow are being reported on KT120 and defective tubes (new) right out of the box for KT150. This does not inspire confidence. Our company had initial issues with the distributor elsewhere mentioned but apparently that has been resolved after we kept send tubes back.
KT120-KT-150
Hello, I am running SE-monos with KT150@50W anode dissipation. What I do see is a dull red glow of the anode in the pin 1 area, the attached picture shows it quite nicely. I do own 4 KT150s, they all show the same behaviour, in both amps. KT120s with the same dissipation settings, however, do not show any signs of anode glow. Did anybody owning KT150s notice a similar behaviour? Would not really like to challenge mine with the rated anode dissipation of 70W.... Thought I bought them from a reliable source, do who knows ? Or this is a KT150 feature, not a failure - they accumulated at least ~150h so far quite happily... Any hint is very much appreciated!
Marcus
Attached Thumbnails
Has anybody wondered why the manufacturer has not published reasonable specifications ?
These are not sufficient at all: http://www.newsensor.com/pdf/tungsol/kt150-tungsol.pdf
Hi All,
Yes, as Bruce says I had four KT120s that showed red at 60 watts total dissipation right out the box. I then returned these and swapped them for 8 x KT150s and of these:
-4 work with no red showing but of these two have quite deformed glass bulbs
-4 were defective. 2 of these showed red, while of the other pair, one made loud cracking noises out the box and both valves in that pair could not be balanced for dissipation.
So quality is a serious issue with these Russian tubes. I have had similar problems with Electro Harmonix and Sovtek output tubes too. Strangely enough I have had no problem with their small signal tubes.
I will continue to get these tubes from a sympathetic dealer who replaces them and credits return postage if there's any problem until I get satisfactory tubes.
David
Hi all,
seems that indeed the manufacturing quality is not entirely stable. Would also guess that missalignment might be the issue. If I change my KT150s for KT120s with the exact same settings (460V/110mA) there is no indication of any red plating..might be unlucky with my 150s, but lucky with my 120s
Marcus
supposedly Shuguang makes KT120's.
Treasure KT120-Z CB @ $262.00 per pair.
Not ready to jump on that boat just yet.
Stu
Hi, To add to the fury.... A licensee in the UK of some of our company's designs has reported the same thing. The tubes are used in push-pull with a CCS and are well within spec. Red anode stripes and glow are being reported on KT120 and defective tubes (new) right out of the box for KT150. This does not inspire confidence. Our company had initial issues with the distributor elsewhere mentioned but apparently that has been resolved after we kept send tubes back.
Attachments
I have got some issues with KT150 about 3 years ago. The lasts I used, 16 pcs, are running fine int the last 6 months without any problems. I think that in the beginning some trouble they have had.
Regarding the egg shape that can attract clients the question is simple. If you have used the 150 or if you haven't.
And there is a great difference.
Walter
Regarding the egg shape that can attract clients the question is simple. If you have used the 150 or if you haven't.
And there is a great difference.
Walter
I am thinking of building something like this with 6922 or 6H30 driving MJE15030 type output transistors instead of 6C33. this effectively make the output tube a 6922 / 6H30 which both have excellent curves. A 6H30 could yeild close to 100w with 4 transistors per triode.
I used 6N6 and 6H30, the 6N6 is in second place respect 6H30 but better than ECC99, another good tubes for splitter. In case 7044, 6463 or 6350 are other choice. I used also a ECC81 in Srpp for first stage with a good results.
Walter
Walter
Hi all,
Google brought me here (great, I'm member anyway).. 😉 I read this whole thread, insteresting talk so far.. great comments. I thought I might ask you about my plans..
Among the considerations everybody else might have too like efficiency, output power, stability, etc. I would tune my choice of amp design into following direction:
- triode mode (distortion characteristics vs pentode mode) ?
- ~200W into nom. 8 Ohm (yeah, lot..)
- speaker driver "Re" is at 5.4 Ohm, this is the impedance minimum (manufacturer states nominal 8 Ohm) so medium-low impedance driving capability should be safe too when more currents rush into the load
- reliability and long term usability is a prio over heavy output power (it will be powerful enough anyway).. driving the tubes safely below factory limits
- I'd rather opt for a balanced Class A window when listening at home at low volumes than instantly going into AB.
Maybe you can provide me some hints out of your experience, a recommended design (we'll resize accordingly) .. or just in general, any innovative idea of how to compensate small tube differences (manufacturing spread) within 1 tube block and how to deal with tube wearing, failing tube (protection of the others and the amp itself), etc. ?
I think of some kind of monitoring / diagnostics / auto biasing solution, I'm going to embed an Arduino based microcontroller which can be used to take care of all such functions and wear, running hours count, warnings, whatever. It will display some basic info on a small OLED screen anyway and also take care of heating monitoring, controlling the power-on relays, infrared remote etc.
Why I'm asking all this here: the topic was interesting and originally I was shooting for KT150s but the reliability of them is a question for me now. Or isn't it anymore ? Are they safe to buy today ? Money is not unlimited but I'm building for the long run so then I would accept some extra 1-time cost now. I'm still open to more reliable tube types like JJ KT88s and use +1 more (per side). The topology is parallel pushpull anyway so then 2 or 3 tubes per wave side.. doesn't matter imho that much (vs. single-tube SE). No problem for me to use 3xKT88s (per side) instead of 2xKT150s when matched and small imbalances can be compensated safely without compromising sound quality.
Google brought me here (great, I'm member anyway).. 😉 I read this whole thread, insteresting talk so far.. great comments. I thought I might ask you about my plans..
Among the considerations everybody else might have too like efficiency, output power, stability, etc. I would tune my choice of amp design into following direction:
- triode mode (distortion characteristics vs pentode mode) ?
- ~200W into nom. 8 Ohm (yeah, lot..)
- speaker driver "Re" is at 5.4 Ohm, this is the impedance minimum (manufacturer states nominal 8 Ohm) so medium-low impedance driving capability should be safe too when more currents rush into the load
- reliability and long term usability is a prio over heavy output power (it will be powerful enough anyway).. driving the tubes safely below factory limits
- I'd rather opt for a balanced Class A window when listening at home at low volumes than instantly going into AB.
Maybe you can provide me some hints out of your experience, a recommended design (we'll resize accordingly) .. or just in general, any innovative idea of how to compensate small tube differences (manufacturing spread) within 1 tube block and how to deal with tube wearing, failing tube (protection of the others and the amp itself), etc. ?
I think of some kind of monitoring / diagnostics / auto biasing solution, I'm going to embed an Arduino based microcontroller which can be used to take care of all such functions and wear, running hours count, warnings, whatever. It will display some basic info on a small OLED screen anyway and also take care of heating monitoring, controlling the power-on relays, infrared remote etc.
Why I'm asking all this here: the topic was interesting and originally I was shooting for KT150s but the reliability of them is a question for me now. Or isn't it anymore ? Are they safe to buy today ? Money is not unlimited but I'm building for the long run so then I would accept some extra 1-time cost now. I'm still open to more reliable tube types like JJ KT88s and use +1 more (per side). The topology is parallel pushpull anyway so then 2 or 3 tubes per wave side.. doesn't matter imho that much (vs. single-tube SE). No problem for me to use 3xKT88s (per side) instead of 2xKT150s when matched and small imbalances can be compensated safely without compromising sound quality.
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I suggest that you go over Patrick Turner's site for some insight on triode vs. pentode output. 200W parallel triode output is doable but asking a lot. If you want reliability, then clearly KT88 has a superior and longer track record than the KT150.
At this moment there are four pairs fo monos with 4 x KT150 running since 1 year and no fail on them
2 pairs normally workin around 4 hrs/day driving a pair of B&W 800 in bi-wiring
It seems that the last batch are better than the older.
Walter
2 pairs normally workin around 4 hrs/day driving a pair of B&W 800 in bi-wiring
It seems that the last batch are better than the older.
Walter
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