Ideas for active valve speakers

[Vuokko]

Hello!

I've been thinking making nice looking and sounding active speakers. Right now I'm searching components to use in build. Has anyone tried this before?

Probably sensitive elements must be used to get the load easier for amplifiers. Do I need to anything special when making active crossover? Also links for good information that I should also read is welcome.

Does anyone have good suggestions for elements or good cabinet enclosures?

[gfiandy]

If you want to create active valve based speakers. You need a valve amp design ( I would leave this alone) and a line buffer stage (probably just a single valve) then use passive filter design between buffer stages. I would avoid trying to make active feedback based filters as tube stages do not really alow you enough feedback for this to work well.

If you look at how tone controls are implmented in radiogram circuits this would give you a good pointer in the right direction.

Regards,
Andrew

[tvrgeek]

Active speakers imply the amp built into the speaker. Not a good idea with valves. They are very microphonic and need lots of air. Never mind how large they are. ( iron etc) Have you considered placing the amps/crossovers on the floor right behind the speakers? Then you only have 3 or 4 feet of wire to each driver. I have seen some ideas with a central power supply. Might hang out over on the tube forum and see what kind of responce you get there.

I am big on bi-amping as it solves so many crossover and driver interaction problems, but it is very expensive to do well.

[planet10]

Originally Posted by tvrgeek

Active speakers imply the amp built into the speaker.

Depends on your definition of active... which apatently no one can decide on.

Building active loudspeakers...

dave

[Brett]

Originally Posted by Vuokko

Hello!

I've been thinking making nice looking and sounding active speakers. Right now I'm searching components to use in build. Has anyone tried this before?

Did it with horns years past, but just go the high efficiency route and use good SS now. Amp sonics are over rated.

Originally Posted by Vuokko

Probably sensitive elements must be used to get the load easier for amplifiers. Do I need to anything special when making active crossover? Also links for good information that I should also read is welcome.

Efficiency is a good thing if using low power amps and you want real dynamic range.

Rod Elliott bi-amping pt1
Rod Elliott bi-amping pt2
Active_Crossovers_and_Filters.pdf

Originally Posted by Vuokko

Does anyone have good suggestions for elements or good cabinet enclosures?

If you are more specific about size, cost, output, lower end performance etc then I might be able to suggest something.

Originally Posted by gfiandy

If you want to create active valve based speakers. You need a valve amp design ( I would leave this alone) and a line buffer stage (probably just a single valve) then use passive filter design between buffer stages.

Broskie's already done all the work for you.
Tube-Based_Crossovers.pdf.

[Vuokko]

Originally Posted by Brett

Did it with horns years past, but just go the high efficiency route and use good SS now. Amp sonics are over rated.

Efficiency is a good thing if using low power amps and you want real dynamic range.

Rod Elliott bi-amping pt1
Rod Elliott bi-amping pt2
Active_Crossovers_and_Filters.pdf

Thanks for the links. Those will be my bedtime stories today.

Originally Posted by Brett

If you are more specific about size, cost, output, lower end performance etc then I might be able to suggest something.

If I can keep it some kind of reasonable price range like below 1000 euro/ speaker it would be nice. And yes. I was thinking about putting the tubes on top of speaker to glow nicely. Like they have put in here: 2.0 Valve / Vacuum Tube Active Speaker (M20MKIII) - China active speaker, valve, vacuum tube in Amplifier Naturally knobs in speaker are ugly so let's put them behind.

But the speaker could be bigger and bi amped with active tube cross-over. floor model could give some good distance to avoid microphonic efects.

So good speaker design is something that I search for. Starting everything from scratch and all the testing won't be that interesting. And I believe that 2-way system with sensitive elements giving frequencey response 40-20000 Hz should be good. Below 40Hz is job for subwoofer and tube amplifier isn't going to be optimal at that low frequencies.

Originally Posted by Brett

Broskie's already done all the work for you.
Tube-Based_Crossovers.pdf.

I also found this: Tube Active Crossover

I believe that tubecad will also be one of those things that I will buy.

[tvrgeek]

Originally Posted by planet10

Depends on your definition of active... which apatently no one can decide on.

Building active loudspeakers...

dave

I don't see any conflict in definition. Active speaker being one with the amps built in to the unit, requiring only line level input and a source of power. If multi-way, as this is the multi-way forum, one usually expects the crossovers built in as well. A typical store-bought sub is "active". The little altec speakers on my computer are "active"

If you have another definition, please explain it.

My point was that valve amps are physically quite large, require good ventilation, and very much do not like vibration. This makes them not well suitable for use in an active speaker, as defined above. Not that it could not be done with sufficient funding.

[Brett]

An active speaker is one that uses a line level XO of whatever type and individual amplifiers for each frequency range directly connected to the drivers. The electronics do not need to be physically in the speaker enclosure for it to be active.

[tvrgeek]

Vuo, if you do consider valve based crossover and amps, consider not just piecing together buffers, crossovers, and amps. Look at it from a systems standpoint. What can you do to generate the crossover functions within the amp or buffer stages without separate crossovers? Feedback caps, blocking caps, cathode caps, and of course making use of the drivers natural response. Pick drivers where their natural response can align with the target crossover. You may find you only need an active filter for one stage low pass and the entire transfer function for the tweeters within the amp. This could save you about 6 tubes. Of course this approach is valid in solid state as well. Been there, done that.

[tvrgeek]

Brett,

You described " biamped" not "active". The term comes from normal components. Are there any active, i.e. tubes or transistors, in the speaker, or only passive components, caps and coils.