Hey guys,
I did a little searching and got frustrated when I couldnt find any information on the exact topic I wanted(or at least it wasnt plain as day right in my face)
So.... I thought I'd ask the experts here on DIYaudio
Can Tubes be used for an active crossover?
Do any tube crossovers exist?
The reason I thought about this is because I recently bought some new drivers for my mains(Extremis midwoofers and Vifa DX25 tweeters) and I was thinking about crossovers and was highly considering going active.
Well I thought for a second, active crossovers use transistors. Transistors are also used in solid state amps. While Tubes are also used in amps. So it kinda struck me that MAYBE(big maybe) tubes could also be used in active crossovers.
Any thoughts....?
I did a little searching and got frustrated when I couldnt find any information on the exact topic I wanted(or at least it wasnt plain as day right in my face)
So.... I thought I'd ask the experts here on DIYaudio
Can Tubes be used for an active crossover?
Do any tube crossovers exist?
The reason I thought about this is because I recently bought some new drivers for my mains(Extremis midwoofers and Vifa DX25 tweeters) and I was thinking about crossovers and was highly considering going active.
Well I thought for a second, active crossovers use transistors. Transistors are also used in solid state amps. While Tubes are also used in amps. So it kinda struck me that MAYBE(big maybe) tubes could also be used in active crossovers.
Any thoughts....?
Sure, nothing at all wrong or difficult with the idea.
Audio Research made a tubed crossover, Marchand has them and I'm sure I have seen schematics for others on the net.
Personally, I wouldn't bother with tubes. If you have an issue with opamps you could do a discrete circuit. I'm sure I've seen schematics for those too. I'll look around in my bookmarks.
Audio Research made a tubed crossover, Marchand has them and I'm sure I have seen schematics for others on the net.
Personally, I wouldn't bother with tubes. If you have an issue with opamps you could do a discrete circuit. I'm sure I've seen schematics for those too. I'll look around in my bookmarks.
BassAwdyO said:
Sort of a bizarre comment, since you were the one looking for tube schematics. Do you often search for things you have scorn for?
There are lots: http://www.t-linespeakers.org/tubes/xos.html
BassAwdyO said:
The same could be said for almost any valve circuit in these days of cheap silicon. They are hot, heater requirements make them inefficient (especially in low-power circuits like active crossovers), they no longer enjoy the economies of truly large scale production, and are generally much more expensive than their semiconductor equivalents. There are a few applications where the valve is the more rational choice, but they generally lie well outside hi-fi audio.
That being said, pretty much anything made with semiconductors can be made with valves, and vice-versa. Some solutions, like the OTL valve amp may border on the absurd - but they do work (and some work very well!)
Back on topic!
Have a look at the Tube-Based Crossovers and Active Crossovers and Filters articles from John Broskie's TubeCad Journal. They might contain the information you're looking for.
reinhard:
That is FANTASIC! I'm building some speakers using a Manger Audio MSW drive unit and some bass unit (havn't decided which yet). And I definately want some active crossover action...
Now the question is, can we have some (all?!) details of that lovely unit! Also, what is the high freq band width like? I'm just taking my first steps into the world of tubes and I don't know what to expect in terms of bandwidth. I'm told the Mangers work best with very high bandwidth amps.
Thanks,
Gaz
That is FANTASIC! I'm building some speakers using a Manger Audio MSW drive unit and some bass unit (havn't decided which yet). And I definately want some active crossover action...
Now the question is, can we have some (all?!) details of that lovely unit! Also, what is the high freq band width like? I'm just taking my first steps into the world of tubes and I don't know what to expect in terms of bandwidth. I'm told the Mangers work best with very high bandwidth amps.
Thanks,
Gaz
Tube crossovers work just fine. Bear in mind that people somehow managed to bear up under the horrible strain of needing to divide frequencies in the decades before solid state came along. Currently, I'm using solid state for the lower two sections of my crossover and tubes for the upper two--i.e. quad-amped, with solid state below 250Hz and tubes above.
You can make them as simple or as complex as you like. The simplest arrangement is to put your filter section between two followers. You can, if you're willing to commit to just one amplifier design afterwards, use a single follower stage and put the crossover after the follower, but the frequency will change somewhat if you use a different amplifer with a different Zin.
Go for it.
Grey
You can make them as simple or as complex as you like. The simplest arrangement is to put your filter section between two followers. You can, if you're willing to commit to just one amplifier design afterwards, use a single follower stage and put the crossover after the follower, but the frequency will change somewhat if you use a different amplifer with a different Zin.
Go for it.
Grey
Marchand makes both solid state and tube crossovers in assembled and kit form:
http://www.marchandelec.com/xovers.html
Here's a circuit from glassware (tube cad):
http://www.glass-ware.com/tubecircuits/Tube_Crossover_2.html
And another with PCB files:
http://www.pmillett.addr.com/tube_active_crossover.htm
A version by Steve Bench:
http://home.zonnet.nl/horneman/tbcross.htm
Hope this helps.
http://www.marchandelec.com/xovers.html
Here's a circuit from glassware (tube cad):
http://www.glass-ware.com/tubecircuits/Tube_Crossover_2.html
And another with PCB files:
http://www.pmillett.addr.com/tube_active_crossover.htm
A version by Steve Bench:
http://home.zonnet.nl/horneman/tbcross.htm
Hope this helps.
That would probably be steve bench:s design It simple and dosent use a lot of tubes. But do mind it don´t like heavy loads and needs a low impedance preamp to work properly since it does not feature any input buffer.
But I think you would want an active crossover who also incorporates something to deal with baffle step response and maybe even a few µS timedelay for the tweeter.
/ Mikael
But I think you would want an active crossover who also incorporates something to deal with baffle step response and maybe even a few µS timedelay for the tweeter.
/ Mikael
BassAwdyO said:
Things are very dependnt on what your speaker needs. The cheapest -- and in many ways most elegant -- way to do it is to embed the crossover in your amps (ie suitably shrinking the coupling cap between the driver and the output stage gives you a 1st order high pass filter, appropriatly size an input cap & it is 2nd order)....
dave
Can I add some thoughts here for comment?!?
My background is in PA systems and speaker design, and I am looking to upgrade my HiFi system. No amps (tube or otherwise) seem to be able to deliver good bass control AND free-breathing highs, so I am now looking at a simple system of an amp with integral 3 pole x-over, a bass amp part with 4xel34 PSE amp, and a treble amp part of 1xel34 SE design. The speakers I have (Ruark) are great and x-over at 4kHz. I will balance the gain of the bass and treble parts accordingly, and as the CD player has a high enough output already, a simple passive pre-amp will suffice. My lovely vinyl will then have to wait for a phono pre-amp at a later date.
Has anyone tried this before (of course they have), and what have been their thoughts and experience on using such an approach.
Many thanks!
My background is in PA systems and speaker design, and I am looking to upgrade my HiFi system. No amps (tube or otherwise) seem to be able to deliver good bass control AND free-breathing highs, so I am now looking at a simple system of an amp with integral 3 pole x-over, a bass amp part with 4xel34 PSE amp, and a treble amp part of 1xel34 SE design. The speakers I have (Ruark) are great and x-over at 4kHz. I will balance the gain of the bass and treble parts accordingly, and as the CD player has a high enough output already, a simple passive pre-amp will suffice. My lovely vinyl will then have to wait for a phono pre-amp at a later date.
Has anyone tried this before (of course they have), and what have been their thoughts and experience on using such an approach.
Many thanks!
I'll have to dig it out of the closet, but I have an old Lux tube crossover. 3-way, all triode. Each filter is selectable 6/12 dB/octave. Frequencies are controlled via little plug-in boards with the filter caps soldered on them. Q is adjustble. Pretty cool unit. The one I have had some PS mods done to it.
Gizmo talked about this unit as being part of his epiphany on going all-tube active, but otherwise I didn't get much info on it when I googled. It's on my 'should probably think about selling, since I'm not going to use it' list, if there is any interest.
Gizmo talked about this unit as being part of his epiphany on going all-tube active, but otherwise I didn't get much info on it when I googled. It's on my 'should probably think about selling, since I'm not going to use it' list, if there is any interest.
The other point of the posting was to ask whether other people had tried using a quad PSE amp for the bass and a single SE amp for the treble? It seems that the quad PSE gives better bass control at the loss of HF, whilst a single SE has great HF at the cost of poorer bass. I was thinking about putting both of these and a crossover in a single unit (monoblock?).
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