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ALK Crossovers


mkane

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Mike,

 

You make a pretty good case for the very low watt amps.  I think your math was correct.

 

However, I have been using the swamped ALKs for probably 10-12 years with different horns and drivers,and found they can support just about anything.  I prefer the extreme slope versions myself. I am using these networks with an outboard EQ on the tape monitor loop and with higher powered amplifier such as 60 wpc VRD tube amps, and Mac MC250 and 2100 (50 and 100 wpc). 

 

I am interested in any comments you may have concerning this application.

 

This is the same combination Roy demo'd to us in Hope on a Jub vs. the active version he had at the time on the other Jub.  I do remember we listened to this for quite a while.  It was a solution a few of us had been using and brought it to Roy to try.  If you remember he used my DBX 1231 EQ to correct the FR of the 402 with the Jub in the chamber.  It was unable to exactly match the digital crossover response but came very close.

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2 hours ago, mark1101 said:

Mike,

 

You make a pretty good case for the very low watt amps.  I think your math was correct.

 

Thanks Mark....

 

2 hours ago, mark1101 said:

However, I have been using the swamped ALKs for probably 10-12 years with different horns and drivers,and found they can support just about anything.  I prefer the extreme slope versions myself. I am using these networks with an outboard EQ on the tape monitor loop and with higher powered amplifier such as 60 wpc VRD tube amps, and Mac MC250 and 2100 (50 and 100 wpc). 

 

I am interested in any comments you may have concerning this application.

 

This is the same combination Roy demo'd to us in Hope on a Jub vs. the active version he had at the time on the other Jub.  I do remember we listened to this for quite a while.  It was a solution a few of us had been using and brought it to Roy to try.  If you remember he used my DBX 1231 EQ to correct the FR of the 402 with the Jub in the chamber.  It was unable to exactly match the digital crossover response but came very close.

 

Mark I assume you are wanting to stay analog only in this system and my comments are based on this assumption.

 

Obviously so far what  you are doing is working out well for your specific applications.

I also prefer the extreme slope filters whenever possible.

Your amp choices have the power reserve needed for your application.

Applying any frequency spectrum correction in front of the amplifier by using an EQ is a wise choice IMO for your application.

 

The possible drawbacks in your situation using the passive network:

The inability to change the crossover point. You could someday find that the optimum crossover region other than the one your network provides could be needed.

No Time Alignment capability which can offer a further improvement in the crossover region.

 

I do remember the demo and it did offer a close sound reproduction to the active setup.

 

miketn

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1 hour ago, Schu said:

Is there any influence in the fact that a passive XO is "black" by nature, and an active requires/introduces energy in the form electricity?

 

See https://en.wikipedia.org/wiki/Audio_crossover#Classification_based_on_components

 

"Black" is an interesting audiophile meme.  I don't know what it means.  I do know that the use of active crossovers eliminates a set of components between your drivers and your amplifiers--components that change their behavior with age and with load (i.e., voice coil and passive component heating). 

 

Amplifiers on the other hand like to be direct coupled to drivers; they have much more trouble with passive reactance inserted into their load loop.

 

I've never seen a hi-fi sound reproduction system without amplifiers...or acoustic drivers.

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5 hours ago, Schu said:

Is there any influence in the fact that a passive XO is "black" by nature, and an active requires/introduces energy in the form electricity?

 

Passive crossovers waste energy, which isn't a big deal if you have the power to waste. 40 watts active sounds as loud as 100 watts into the same speaker passively crossed.

 

A person could build a line level passive crossover that would look schematically like a loudspeaker crossover, except that the caps and inductors would be  smaller values, thus cheaper. If you want to try some boutique caps they will be more affordable.

 

Time alignment can be done by physically moving the drivers, if possible.

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I vaguely recall the "horns love tubes" thing with respect the speakers having a rising impedance with frequency (typical of horns).

 

The rising impedance with frequency was supposed to have a nice "taming the horns" effect when used with tube amps - in the high mid-range where too much is most noticeable... some kind of synergy resulting in a naturally well behaved frequency response (that was nicer than when using solid state, for which the tonal balance was not originally designed?).

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"A passive crossover requires no power at all"

 

Incorrect.

 

The loss is in the ESR of the caps, and the DCR of the woofer inductor.

 

The loss in the woofer inductor is quite high on old type 'A' and 'B' networks, enough to be significant with flea-powered triode amps.

 

Some of the newer networks were designed for high DCR inductors though, and the DCR should not be changed.

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10 hours ago, RoboNerd said:


You guys just don't get it!

You get on here a ***** about the loss of a tiny fraction of a watt of power in an inductor or in ALK's swamping resistor while every night-light in every room of your house sucks up 7W. Every incandescent light in your house generates more heat then light. Every electronic device in your house that has an on/off on it's remote control is drawing power 24 / 7. If you have a satellite receiver it is running continuously just to retain the channel guide. Every room in your house is a comfortable 72 degrees even when you are not in it. How may Watts is that wasting? GET REAL and move on!

 

The nerd.

 

 

You apparently do not realize that none of these devices are audio components. You are the one who needs to "get real".

 

The reality is that every passive crossover has insertion losses. Using a passive crossover with swamping resistor(s) eats power in the crossover region, possibly doubling current draw from the amplifier. This will cause distortion if one is using flea powered amplification and playing too loudly. This is not about additional current draw from the wall socket. It's about current draw from the amplifier.

 

 

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hopefully robo nerd will take a powder or at least learn some online etiquette.  calling bullshit on basic electronic principals is plain stupid.  he may claim that the losses are not significant  or audible in his opinion but not call bullshit.  I have noticed the site degrading over time as most everything becomes a quick tempered, almost religiously charged atmosphere. glad to see that the old timers stick around to post even in this environment.  T

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4 hours ago, RoboNerd said:

I just looked up the specifications on the 2A3 vacuum tube. The filament requires 2.5V at 2.5 amps to light it. That is 6 1/4Watts of power WASTED!

 

No surprise. Single-ended directly heated triode amplifiers are the some of the most inefficient amp circuits out there with regard to wasted heat and power.

But to some it's worth that wasted energy for the class A directly heated triode sound.

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