Tube hybrid - split from CA340A thread

[MJL21193]

Originally posted by mikesnowdon
You never know, maybe hes thinking of a tube hybrid conversion? Which would be fine, its all about experimenting, if we didn't we'd never advance as a race....

Ironic. Using tubes is de-evolution, a step backwards.

[anatech]

This thread was split off from
[http://www.diyaudio.com/forums/show...threadid=131847]CA 340A SE LM3886 based amp - Upgrade advice please.[/URL] as the discussion veered into tube territory. I'm leaving it in this forum since the discussion is not in depth.

I feel there is some useful information or opinions that may interest some people currently comfortable with "chip amps". Just another technology to consider.

The beginning of this discussion is found here. This may help put it into perspective for those who didn't see it develop.

-Chris

[anatech]

Hi John,

Ironic. Using tubes is de-evolution, a step backwards.

I don't agree. Tubes are an earlier device that are a mature technology. We now have better components that were not available back when tubes were a mainstream device, but I think that engineers did a better job with what they had to work with than is done these days in consumer electronics.

Tubes have some admirable attributes, and if you look at the as another component type at your disposal, some interesting design ideas materialize. These devices are a voltage to current converter with their own characteristics. Similar to J Fets, but different. More robust in some ways and problematic in others.

I am looking forward to playing with them in the near future, more than I have in the past. Try to regard these from a viewpoint of a new component that is well understood. You can use them with semiconductors to leverage the best characteristics in both.

If you have the time, try to find a book by Morgan Jones called "Valve Amplifiers". The explanations are concise with easy text to read and understand. I suspect you would enjoy this book on it's own merits. Available from Amazon easily. I'm happy I bought my copy and Morgan will be publishing a revised edition soon. This text does present the theory and pitfalls without diving into pages of math. You get the understanding without excessive suffering.


-Chris

[planet10]

Originally posted by MJL21193
There doesn't seem to be anything in audio that can't be done as well or better than a tube circuit with solid state.

Well except for sonics... trust me we have been (continue too) searching for a SS amp that sounds as good as the tube ones we have made. Next up F1, F2, F4.

dave

[MJL21193]

Thanks for the tip on the book Chris,
I see tubes as bulky, awkward and fragile. Expensive, high voltage and eventually wear out after a performance decline. It is nostalgia and the concept that they will make a better sounding amp that drives their revitalized popularity. There doesn't seem to be anything in audio that can't be done as well or better than a tube circuit with solid state. It has been demonstrated that a solid state amp can be made to sound indistinguishable to a tube amp - this I'm sure you know about as it was the work of Carver.
I have a small class A amp that uses a tube input stage - a 12AX7 and although it sounds good, I don't think this is due to the tube.
That will be my first and last foray into the thermionic past.

[MJL21193]

Originally posted by planet10
...trust me

Of course I trust your judgment - you turned me around to enabl.

I guess you like the colouration that tubes add. That's fine, but we can add colouration with solid state too, no? Carver did it and fooled many a "trained" ear.
My point is that the real appeal of tube gear is not sound quality. Why are so many of the units we see made with their parts exposed? Better to ooh and ahh over.

I stand stroking my beard, regarding the valve amp with a critical eye, and turn to my fellow to warn him to be careful - high voltage!

[planet10]

Originally posted by MJL21193
I'm sure you know about as it was the work of Carver.

We tried to duplicate that result and failed.

dave

[anatech]

Hi John,
Properly designed tube equipment minimizes tube aging problems. Amplifier output stages are the only areas where tube aging is a concern. Many tubes run with 50 ~ 90 VDC on their plates. Some types are designed to run off as little as 12 VDC B+.

I agree they can be bulky. Modern designs seem to run large power transformers and overly complicated power supplies that dissipate too much heat. It doesn't have to be that way these days. Especially considering the newer components we have at our disposal. Dropping a tube is often the end of it, however the sane can be true for some power transistors and capacitors.

As far as better performance from solid state designs. I don't fully accept that. Good sounding solid state amplifiers are rare. Some of the better designed tube stuff is very good, but also in a minority. they both can be very good performers - or not. Depends on the skill of the designer. I have mentioned I use both tube and solid state equipment. They each have their place in the world I think.

As for Morgan's book, it will answer most of your questions. More over, reading it may change your mind on these things. I should stress that I don't believe tubes are the only way to audio nirvana. A balanced view of each is all that can be recommended.

Audio colouration. The better designs minimize this no matter what device family they use. Your small class A tube amplifier probably does have a distinct sound. That doesn't mean they all do. As far as making them visible, okay. Why not? I like the visual effect tubes have in the darkness when on. As long as they are not subjected to noise pickup, I have no problem with this. Transistors and ICs lack the visual attraction that running tubes have. Generally speaking, an exposed tube runs cooler unless effort is made to properly ventilate tubes inside an enclosed chassis. It can be done though.

-Chris

[planet10]

Originally posted by MJL21193
I guess you like the colouration that tubes add.

A lot (most) classic tube gear is "colorful", and quite a bit of modern stuff trying to recreate the nostalgia... but there is nothing inherent in tubes that requires them to be coloured. Properly used it is possible to make devices that are VERY good... and it is a lot easier than with SS stuff...

I'll let you get back to your HT receiver...just don't ask me to live with it.

dave

[anatech]

Hi Dave,

We tried to duplicate that result and failed.

Bob did get it to work. Not too surprising from where I sit. Consider the amplifier in question as a black box with a transfer characteristic. It doesn't matter what's in the box if that characteristic is the same. Overload or clipping behavior will differ though. I imagine with enough money and time, that can be solved also.

Another point to all this is that we humans are not that good as test instruments. Suggestion is far too powerful to allow our hearing and opinions to be trusted completely.

Let's just say there is excellence with both technologies and leave it at that.

-Chris