KT150

Paul Barker · Post by **Paul Barker** » Sat Aug 31, 2013 8:02 am

Also, though I cannot promote PSVane because I haven't heard them. It is perhaps time to take a gamble on something like pair of "hifi" 845's for £175 including all import duties and VAT paid with a VAT receipt.

Perhaps they are better made than the Chinease 845's and 211's which I have experienced that I would compare in same way I would compare a Wartburg two stroke to a Daimler double six for smoothness.

No I think they got that kt150 price level wrong. I suppose the guitar boys will find a use for them. Huge market.

your KT120's are far better value, you could also parallel push pull those if you want more power. A quad of KT120's for a little over the price of a single KT150.

Your KT120 sounded great. Going off memory the Chinese 845's and 211's I have used at home were nasty compared to it. I got shot of every single one years ago. Did the show and tell of their nasty quality and sound compared to nos at the last eggborough.

But I am not saying the Chinese can't have improved their production quality.

Post by **Nick** » Sat Aug 31, 2013 10:29 am

I suppose the guitar boys will find a use for them. Huge market.

Not so sure about that. The days of a huge back line of 100W heads is long gone, most valve guitar amps now are in the 35-50 range, many lower. Its more about tone than volume now.

Paul Barker · Post by **Paul Barker** » Sat Aug 31, 2013 12:13 pm

Nick wrote:
I suppose the guitar boys will find a use for them. Huge market.
Not so sure about that. The days of a huge back line of 100W heads is long gone, most valve guitar amps now are in the 35-50 range, many lower. Its more about tone than volume now.

Yes and I suppose they just plug the output of their valve head into the PA.

ed · Post by ed » Sat Aug 31, 2013 12:30 pm

Paul Barker wrote:
Nick wrote:
I suppose the guitar boys will find a use for them. Huge market.
Not so sure about that. The days of a huge back line of 100W heads is long gone, most valve guitar amps now are in the 35-50 range, many lower. Its more about tone than volume now.
Yes and I suppose they just plug the output of their valve head into the PA.

that might give the sound man a few problems.....

Cressy Snr · Post by **Cressy Snr** » Sun Oct 06, 2013 10:36 am

looks like these are now available at Hotrox for £60 each
http://www.hotroxuk.com/tungsol-kt150.html

Still expensive but nowhere near as bad as the £100 that HFW were bandying about.

That price makes a DIY KT150 amp a little more viable now. At £100 it was out of the question.

pre65 · Post by **pre65** » Sun Oct 06, 2013 12:57 pm

You could get a pair of 833a for less than the cost of four KT150.

Cressy Snr · Post by **Cressy Snr** » Sun Oct 06, 2013 2:33 pm

pre65 wrote:You could get a pair of 833a for less than the cost of four KT150.

True Phil, but domestic considerations make 833As impossible.
We have two cats, a dog and three grandchildren who would be killed
by one of those things.
Apart from the sheer horror of such a thing happening to a loved one,
a hefty prison sentence for involuntary manslaughter by gross negligence would be certain.

Some things are best left well alone

Gives me the willies even thinking about it

Greg · Post by **Greg** » Sun Oct 06, 2013 9:18 pm

In comparison to the price of other 'recognised' audio valves, I don't think £240 for a quad is unreasonable. Be sure, if the sound quality is good, as and when KT150 amps come into the market, the valve price will probably rise significantly. I'd at least buy one quad now and work with them. If you like the sound, buy more rapidly. If you don't like their performance, you should be able to sell them on in no time. Remember, in terms of saleability, everything commercially will hinge on power output and magazine reviews. The magazines are almost certain to positively rate them regardless of performance, because the reviewers will be hooking them up with inefficient speakers and will be beguiled by their output power. My view is you have a win, win on this one

Cressy Snr · Post by **Cressy Snr** » Tue Oct 08, 2013 10:53 pm

I'll have to see what Santa brings.

Paul Barker · Post by **Paul Barker** » Tue Oct 08, 2013 11:02 pm

tonight I was with a man who invented something while an undergrad in the Soviet Union when it was communist. Tonight he showed me his papers on the invention in 1991 with all the calculations pages and pages of them.

In the last week or so someone has reinvented his invention and sold his idea to an airline for E63,000,000.

All he could say was "My professor was an idiot for not selling my idea." It was just part of his course work.

Anyway, had the story been different and he had given to me some of his 63,000,000 I would buy you them.

He is a lovely man, and quite philosophical about it.

Alex Kitic · Post by **Alex Kitic** » Mon Oct 14, 2013 3:44 pm

The KT150 could be used in the RH Universal amp instead of a KT88 or 6550. Still, that would be an overkill, since this tube can dissipate up to 70W, and I am not sure whether at 32W dissipation it would last twice longer than a KT88 would at the same dissipation?

In order to exploit this tube fully in the RH Universal, one would have to elevate the B+ above 600V for approximately 60W dissipation. The amp would reach and probably exceed 20W per channel at 1% distortion.

The logic of this would be achieving 20W or more with one tube per channel while not exceeding "standard multimeter territory", i.e. keeping HT voltages below 700V. I guess 600V is less dangerous than 1000V, but nevertheless you probably make such a mistake only once.

Still, it would not be a straightforward application: the bias voltage would probably exceed 35V, thus some measures should be taken to decrease Ug2 to, let's say, 225 or 250V, to keep the bias voltage (grid-cathode differential) at usual KT88 and 6550 levels.

The decrease could easily be achieved either by increasing the value of the zener diodes (a string of 5 75V 5W zeners would do for a decrease of 375V)... or a string of VR tubes which would add to the visual appeal.

IslandPink · Post by **IslandPink** » Mon Oct 14, 2013 6:43 pm

.... or we could just build our own amp, properly, for the KT150 .....

Alex Kitic · Post by **Alex Kitic** » Mon Oct 14, 2013 7:44 pm

IslandPink wrote:.... or we could just build our own amp, properly, for the KT150 .....

To my understanding, the KT150 is a beefed-up KT120, or KT88.

If my assumption is correct, most KT88 amps could be "enlarged" to exploit the higher anode dissipation. That is what I propose, and how I would takle it - and it would have the "RH sound" that many like.

Basic amp schematics and topologies are like hot water, already invented. By approaching this tube differently than I usually do, I would betray my design principles. As for building your own, properly... well, it comes to the same principle: you would just adapt some existing design principle to this tube with higher dissipation rating.

Or is it that you think my proposal is not "proper"?

Alex Kitic · Post by **Alex Kitic** » Mon Oct 14, 2013 7:45 pm

IslandPink wrote:.... or we could just build our own amp, properly, for the KT150 .....

To my understanding, the KT150 is a beefed-up KT120, or KT88.

If my assumption is correct, most KT88 amps could be "enlarged" to exploit the higher anode dissipation. That is what I propose, and how I would takle it - and it would have the "RH sound" that many like.

Basic amp schematics and topologies are like hot water, already invented. By approaching this tube differently than I usually do, I would betray my design principles. As for building your own, properly... well, it comes to the same principle: you would just adapt some existing design principle to this tube with higher dissipation rating.

Or is it that you think my proposal is not "proper"?

pre65 · Post by **pre65** » Mon Oct 14, 2013 7:56 pm

Rhetoric ?

(after reading what's in the link below Alex's post)

audio-talk

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