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ALK Crossovers


mkane

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I have been using the ALK ESNs for over 10 years along with most amps in the 50 wpc range or larger.  Never an issue for me.  Love them.  I use various ALK networks because I felt after many comparisons they were the best sounding and most flexible for my applications.  Not for everyone.  Not trying to sell anyone, but I do prefer them.

 

Thanks for the data John.  That's about what I thought was going on.

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3 hours ago, Marvel said:
12 hours ago, Deang said:

 

2a3 users can pretend they're using 45s. :-)

 

I don't think I am taking that large a hit...:D

 

Then again, the DHA2 probably doesn't suck up as much power as Al's designs. :ph34r:

 

I'm afraid you are Marvel even though it appears to not be causing you any issues in your particular situation. 

 

If I was a low wattage amp user and wanted a little midrange atenuation another option would be to change autoformer taps with a proper capacitor value change to maintain the same crossover frequency and avoid the downside of wasted power using the swamping resistor.

 

miketn 

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Dean, since i moved to my new house and listen to my k-horns everyday now with the ALK's you built for me i noticed that i'm not getting much low end from them so i put in a stock set of 78 AA's and now have way more low end. whatda you think. thanks, Russ

 

 

 

 

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On 11/20/2016 at 3:03 AM, John Warren said:

 

Amp is set at 2V output, 1kHz signal first (top) montage is current (mA) sourced by the amp into a no-shunt autoformer loaded by Klipschorn mid as taps are changed from -3 to -12dB.

 

Second montage is same 2V amplifier settings at 1kHz but with 10 Ohm shunt across input side.    With the shunt across the input side the bulk of current sourced by the amplifier goes thru the shunt regardless of what the taps are doing.  That said, that's the point of the "swamping" resistor.  It makes the impedance somewhat less sensitive to changing the taps because the impedance load presented to the filter is largely determined by the current draw thru the shunt resistor. 

 

That current data is then used to tweak a SPICE model of the circuit to, eventually, determine power.   In the power calc plot, I placed a 60uF capacitor in the circuit between the amp and the shunted autoformer to provide AA type filter.  It assumes the mid is on the -3dB setting.

 

Link shows the analysis

 

http://www.northreadingeng.com/Forums/viewforum.php?f=4

 

no_shunt_current.jpg

shunt_current.jpg

shunt_current_sim.jpg

shunt_current_sim_2.jpg

Thanks for doing this and posting it John, as others have said. Basically what I see from your measurements is what I inherently knew from my previous understanding that the 10 ohm shunt(swamping) resistor across the autoformer draws 200 milliamps at 2Volts. This equates to a 400 milliwatt "loss" or extra power needed from the amp. The Laws of good ol' Mr. Ohm and Mr. Watt again. Fortunately the majority amount of power needed in music goes to the lower frequencies and the compression drivers on the midrange horns most of us use are relatively efficient at converting electrical energy to acoustical energy.

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It's probably because the caps are gone in the AAs and you are not getting the right amount of tweeter.  Makes it sound like more bass.

 

You might also drop the squawker another tap on the ALK.  Too bad no tweeter attenuator on the ALK.  I added them to my lascalas outboard of the networks.  Then you can adjust the tweeter and squawker.

 

Probably nothing wrong with the ALKs.

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18 hours ago, jwc said:

So in terms of "watts"....are we talking about less than 1 watt loss with resistor?

 

The amount of power used is a better term, its not loss because the resister served a function.

 

It's directly proportional to the power input, however at normal listening levels less than a watt.

 

 

HB

 

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4 hours ago, jwc said:

So in terms of "watts"....are we talking about less than 1 watt loss with resistor?

 

It depends on the loudness level you desire at the listening position. See page 6 for my calculations jc. (3 watts dumped into the swamper for 1 watt applied to the midrange)

 

I'm pretty sure you would burn more than a watt knowing the style of music you enjoy jc.:emotion-21:.:D

 

miketn

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1 hour ago, Honeybadger said:
4 hours ago, jwc said:

So in terms of "watts"....are we talking about less than 1 watt loss with resistor?

It's directly proportional to the power input, however at normal listening levels less than a watt.

 

 

HB

 

This begs the question what do you consider normal listening levels..?

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4 hours ago, babadono said:

Fortunately the majority amount of power needed in music goes to the lower frequencies and the compression drivers on the midrange horns most of us use are relatively efficient at converting electrical energy to acoustical energy.

 

In my calculations on page 6 of this thread I presented an simplified example with specific attention on low wattage amplifiers and gave some indication of what that means in relative loudness at the listening position. It should be noted that once we start to amplify a complex wide frequency spectrum musical signal (containing woofer and tweeter signals also) then we would have even less available power from the amplifier and it would reduce the power available across the whole spectrum. Audible Clipping would definitely set in sooner than my simplified example at a lower max SPL than reported in my example from the system and this should be taken into consideration for those using low wattage amplifiers.

 

I am trying my best to give information that is valid and relatable to hopefully help the low wattage amplifier users and those using larger amplifiers can relax:)

 

miketn

 

 

 

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Did PWK ever design amplifiers?

 

There is nothing in the science of amplifier distortion that says higher power necessitates higher distortion. Yes, distortion increases near the limit of the amplifier, but every amplifier has a sweet spot at a different power level - you simply design the amp for the application. In fact - if we were to go in any direction - I would say increasing the voltage swing requirements of the amplifier is of great benefit to the amplifier designer - especially if we're talking active crossovers.

 

All of these ideas need to be analyzed from a system perspective. I've grown to dislike these articles from PWK because it's intentionally obtuse to make a very narrow point. And that narrowness demonstrates a totally wrong way to think about system performance. I know PWK had a better understanding, but you guys use these articles within the narrow perspectives that were presented - and that leads to incredibly unnecessary conclusions.

 

Btw, it's the dumping of energy in Class A amplifiers that makes them such low distortion. The same principals totally apply in other areas of electronics - especially in situations where nonlinearities are present. Speakers and microphones are the two most nonlinear systems in audio that we can't avoid... The electronics side of things is very straightforward.

 

All that to say, there are a lot of amplifiers that are sensitive to the load impedance. There are also a lot of amplifiers that are not very sensitive at all. Some have power headroom - some don't. Just because your favorite amp can't drive a swamping resistor load doesn't mean there isn't sonic benefit to having a flatter load impedance. Likewise, flattening the load impedance doesn't necessarily change the sound in any appreciable way either.

 

These are systems. Looking for rules of thumb to justify your decisions is just odd. Don't be odd. It's bad for the hobby. Oh, and stop wearing sweatpants too. The only way to experience the true plushness of a comfortable chair is to enjoy it in the nude......

 

Edit - I'm looking at this from a perspective that you pick the speakers first, then you find the amplifier that mates with your listening habits and nuances of your speaker. You don't start with the amplifier selection. It's worth mentioning though that the ideal amplifier is likely different for a passive xover versus an active xover setup.

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  • 4 months later...

Hi,

 

I have a pair of Bob Crites Cornscala speakers. It's his newest "B" model.

 

Which ALK crossover would work best? Or is there another maker that you'd prefer? Mine has the 120 tweeter and the md405 mid driver. I'm looking to be able to adjust the tweeter and the mids to suit my room...

 

Thoughts? I really want to make sure my crossover works with the stock drivers this speaker comes with.

 

Many thanks from the newbie.

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