New Crossover Networks

[Deang]

John designed the DHA as a first order filter that like the ALK, would show a benign impedance to a tube amp. I just took it a step further and floated the common connection for the squawker so it could actually be used like an ALK.

Are you still building the Super A for people to use?

I haven't built or sold any of these filter types for some time.

[Erland]

I really like the idea of these simple filters.

I am using ALK ES400/5800 and I like it, but I keep wandering how much I all the components affects the sonics.

I am using Solen caps in the XO.
With all the components, upgrading to highend caps will cost as much as a new car!

I have had some communication with at dealer of some highend comression drivers, and his opinion confirms exactly what you are writing about detail in the music through a simple first order filter.

Greg, I see the basics, but any chance you can print the schematics for your XO.

[tigerwoodKhorns]

I really like the idea of these simple filters.

I know that all of you guys hate B&W's. But, when they designed the diamond 800 series, they moved the new diamond tweeter even lower so that it was closer to the midrange. They said that this allowed them to go with a first order network which was desirable on the tweeter.

[greg928gts]

Are you still building the Super A for people to use?

I haven't built or sold any of these filter types for some time.

The reason I ask is because I want to be able to offer different choices to my customers when they decide to upgrade their Khorns. Right now I can offer them Universal networks that I'm building from kits (I have an agreement with Al on this), I have my new VSi networks, and then Al is working on the ES300 for the V-Trac. But one more network design would be nice. Something between the VSi and the Universal in terms of complexity.

One thing I don't understand is the 2.4mhy inductor shown in the DHA schematic. The Universal uses a 1.3mhy. Don't both cross the woofer at 400Hz?

Greg

[greg928gts]

Greg, I see the basics, but any chance you can print the schematics for your XO.

Sure, I don't mind.

Greg

[Guest David H]

One thing I don't understand is the 2.4mhy inductor shown in the DHA schematic. The Universal uses a 1.3mhy. Don't both cross the woofer at 400Hz?

In the ALK neworks, the 1.0mH inductance of the woofers coil is subtracted from the total inductance needed. Most designs do not take this into consideration.

[greg928gts]

Most designs do not take this into consideration

Technically I know very little about crossover design, but this just seems careless to me. As part of good crossover design, either you do take into consideration the woofer inductance, or you don't. Maybe it's not that black and white.

I'm not understanding the necessity of the swamping resistor in the VSi schematic, or what it is doing exactly. I've asked Al about it, but that just opened up a can of worms LOL that ended up in explanations that make a little sense to me, but then that leads to more questions LOL. Can someone explain it in plain language? Or maybe it can't be splained in plain language.

Crossover explanations for me need to be like this: A single inductor (which is a coil of wire) put in line to the woofer acts as a filter that cuts frequencies above a certain point, allowing the other frequencies below that certain point to go through to the woofer. The size of the wire and the amount of wire in the coil determines where the cutoff point, or crossover point is. Being a single component in line to the woofer makes it a first-order filter and the slope of the signal being cut off will be approximately 6db per octave. In a first order network, the cutoff of frequencies is not like a wall, the frequencies above the cutoff point are still there, but as you go higher and higher in frequency, the output is less and less, and this is what is called the slope. If the crossover frequency is at 400hz, and the slope is 6db, then for every octave of frequencies above 400hz, the output will be 6db less. This means that in this scenario, at 800hz, or one octave above the crossover point, the signal will be 6db less than it is at 400hz, and then at 1600hz the signal output will be 12db less than it is at 400hz, etc...

I know it's a lot of words, but if I could get a whole network explained to me this way, I think I could really understand what each component is doing and what the various parts of the network are doing. With the VSi, I understand what the caps and autotransformer are doing, it's the swamping resistor that needs explanation for me. Would that network work the same way without it?

Greg

[seti]

I really like the idea of these simple filters.

I am using ALK ES400/5800 and I like it, but I keep wandering how much I all the components affects the sonics.

I am using Solen caps in the XO.
With all the components, upgrading to highend caps will cost as much as a new car!

I have had some communication with at dealer of some highend comression drivers, and his opinion confirms exactly what you are writing about detail in the music through a simple first order filter.

Greg, I see the basics, but any chance you can print the schematics for your XO.

From what I can tell from simple to complex networks is that the simple network seems better at lower volumes and the more complex extreme slope network seems to fair better at higher volumes. Nothing wrong with having a couple networks to try. It took me a while to prefer the ESN networks but now I am sold on them.

[seti]

Most designs do not take this into consideration

Technically I know very little about crossover design, but this just seems careless to me. As part of good crossover design, either you do take into consideration the woofer inductance, or you don't. Maybe it's not that black and white.

I'm not understanding the necessity of the swamping resistor in the VSi schematic, or what it is doing exactly. I've asked Al about it, but that just opened up a can of worms LOL that ended up in explanations that make a little sense to me, but then that leads to more questions LOL. Can someone explain it in plain language? Or maybe it can't be splained in plain language.

Crossover explanations for me need to be like this: A single inductor (which is a coil of wire) put in line to the woofer acts as a filter that cuts frequencies above a certain point, allowing the other frequencies below that certain point to go through to the woofer. The size of the wire and the amount of wire in the coil determines where the cutoff point, or crossover point is. Being a single component in line to the woofer makes it a first-order filter and the slope of the signal being cut off will be approximately 6db per octave. In a first order network, the cutoff of frequencies is not like a wall, the frequencies above the cutoff point are still there, but as you go higher and higher in frequency, the output is less and less, and this is what is called the slope. If the crossover frequency is at 400hz, and the slope is 6db, then for every octave of frequencies above 400hz, the output will be 6db less. This means that in this scenario, at 800hz, or one octave above the crossover point, the signal will be 6db less than it is at 400hz, and then at 1600hz the signal output will be 12db less than it is at 400hz, etc...

I know it's a lot of words, but if I could get a whole network explained to me this way, I think I could really understand what each component is doing and what the various parts of the network are doing. With the VSi, I understand what the caps and autotransformer are doing, it's the swamping resistor that needs explanation for me. Would that network work the same way without it?

Greg

This might be wrong but I think the swamping resistor is to change the impedance of the hf to match the lf. At least that is what I was told it did on mine.

Do you have testing equipment a mic rta software and a laptop? I hope so with all that speaker building you do. You could always get some parts together and do some crossover experiments on just a single driver that could be verified through measurements. That could lead to some answers or maybe even more questions.

[tigerwoodKhorns]

Very attractive Greg, those will probably work great with small Decware EL84 set amps.

I have to admit I was sceptic about the no woofer inductor crossover, but I recall a Dope from Hope article that PWK conducted a blind test, and the pannel of listeners actually prefered it.

Which Dope from Hope (Volume and article or title)? I have the collection but cannot find it.

[tigerwoodKhorns]

Most designs do not take this into consideration

Technically I know very little about crossover design, but this just seems careless to me. As part of good crossover design, either you do take into consideration the woofer inductance, or you don't. Maybe it's not that black and white.

I'm not understanding the necessity of the swamping resistor in the VSi schematic, or what it is doing exactly. I've asked Al about it, but that just opened up a can of worms LOL that ended up in explanations that make a little sense to me, but then that leads to more questions LOL. Can someone explain it in plain language? Or maybe it can't be splained in plain language.

Crossover explanations for me need to be like this: A single inductor (which is a coil of wire) put in line to the woofer acts as a filter that cuts frequencies above a certain point, allowing the other frequencies below that certain point to go through to the woofer. The size of the wire and the amount of wire in the coil determines where the cutoff point, or crossover point is. Being a single component in line to the woofer makes it a first-order filter and the slope of the signal being cut off will be approximately 6db per octave. In a first order network, the cutoff of frequencies is not like a wall, the frequencies above the cutoff point are still there, but as you go higher and higher in frequency, the output is less and less, and this is what is called the slope. If the crossover frequency is at 400hz, and the slope is 6db, then for every octave of frequencies above 400hz, the output will be 6db less. This means that in this scenario, at 800hz, or one octave above the crossover point, the signal will be 6db less than it is at 400hz, and then at 1600hz the signal output will be 12db less than it is at 400hz, etc...

I know it's a lot of words, but if I could get a whole network explained to me this way, I think I could really understand what each component is doing and what the various parts of the network are doing. With the VSi, I understand what the caps and autotransformer are doing, it's the swamping resistor that needs explanation for me. Would that network work the same way without it?

Greg

Here is a simple explanation that I found:

In general, a swamping resistor is a current limiter
in AC and RF circuits used to reduce impedance variations that limit
bandwidth.

The 100-ohm resistor in series with an impedance that varies between
2ohms and 20ohms, for example, will appear to be an impedance that
varies between 102ohms and 120ohms, much flatter, at the cost of
efficiency due to power lost to heat in the resistor. One might say
that the impedance variation of the circuit has been swamped, or
overwhelmed, by the dominating resistance.

[greg928gts]

Do you have testing equipment a mic rta software and a laptop? I hope so with all that speaker building you do. You could always get some parts together and do some crossover experiments on just a single driver that could be verified through measurements. That could lead to some answers or maybe even more questions.

I desperately need to find someone to help me design and test speakers. I've been trying to hook up with someone for almost two years now. I even flew to Toronto Canada one time to meet with someone I thought might be a good candidate. It didn't turn out. I've spent time on hundreds of emails with people who I thought might be able to work with, but nothing has worked out yet. One VERY qualified person expressed interest, but the cost per hour was very high for me, and there was no telling how much time we would spend on even just one design, so I didn't think I could do that right now.

I don't want someone to teach me, I want someone to work with me directly. With electronic communications the way they are these days, there's no reason why I can't partner with someone to test speakers in my shop in Benton Maine, while they are located wherever in the world.

Not having someone to work with on a technical level is really holding me up on a lot of things. Right now I'm only able to develop known ideas or to change things aesthetically, or to market myself and my products.

I'm not going to learn the technical aspects of speaker design. My brain just can't wrap itself around those concepts. I've tried, it just ain't happenin! Not in this lifetime anyway. But I shouldn't have to, there's plenty of people out there capable of doing that work. I need to concentrate on the things that I do well and subcontract those that I don't. It's harder than you think to find someone though. Some generous souls from this forum have tried to help me and I have a way of tiring them out I think! LOL Since the emails slow down and stop after some time. LOL It is hard to do.

Greg

[JohnA]

Most designs do not take this into consideration

Technically I know very little about crossover design, but this just seems careless to me. As part of good crossover design, either you do take into consideration the woofer inductance, or you don't. Maybe it's not that black and white.

I'm not understanding the necessity of the swamping resistor in the VSi schematic, or what it is doing exactly. I've asked Al about it, but that just opened up a can of worms LOL that ended up in explanations that make a little sense to me, but then that leads to more questions LOL. Can someone explain it in plain language? Or maybe it can't be splained in plain language.

Greg

Well, let me give it a shot.

The quick answer has been stated already, the swamping resistor dominates the overall impedance so much that other changes are insignificant. To elaborate: total parallel resistance is 1/Rtotal = 1/R1 + 1/R2 + 1/R3 +......

So, 1/Rtotal = !/10 + 1/32; 1/Rtot = 0.1 + 0.03125; Rtot = 7.62. You can see that the impedance of the driver through the autoformer is so small, 0.03, compared to the resistor, 0.1, that any change would cause only a small change in the overall impedance.

Changing the tap to -6 dB would give 1/10 + 1/64 = 1/0.1156 = 8.65. Doubling the impedance of the driver only raised the total impedance 1 ohm (14%).

Now, for the voice coil inductance "problem". Most crossover designs do not consider the voice coil inductance because they are designed to "see" an impedance equal to the complex (mathmatically) sum of voice coil resistance + inductance. Al has chosen to model the 2 parts seperately. His computer program can do that. It would be quite difficult to do that by hand. It might be more accurate, but is considered unnecessary, especially in low order networks. It is hard to speak of accuracy and 6 dB crossovers in the same sentence. Either method considers the inductance, but does it differently.

[Guest David H]

Very attractive Greg, those will probably work great with small Decware EL84 set amps.

I have to admit I was sceptic about the no woofer inductor crossover, but I recall a Dope from Hope article that PWK conducted a blind test, and the pannel of listeners actually prefered it.

Which Dope from Hope (Volume and article or title)? I have the collection but cannot find it.

Don Richard posted this reply earlier, I found mention of this in The Dope From Hope Vol.12, No.2, March 1972. Bypassing the woofer inductor improved frequency response in the 250-350 Hz range by 3 dB on the Khorn. I tried this years ago and found a slight improvement, so I left the inductor bypassed. The Khorn bass enclosure has a natural rolloff above 350 Hz so the inductor serves little purpose anyway.

I am sure this is the article I was referring to, I read it quite some time ago and may not have done it justice.

[Guest David H]

Well, let me give it a shot.

The quick answer has been stated already, the swamping resistor dominates the overall impedance so much that other changes are insignificant. To elaborate: total parallel resistance is 1/Rtotal = 1/R1 + 1/R2 + 1/R3 +......

So, 1/Rtotal = !/10 + 1/32; 1/Rtot = 0.1 + 0.03125; Rtot = 7.62. You can see that the impedance of the driver through the autoformer is so small, 0.03, compared to the resistor, 0.1, that any change would cause only a small change in the overall impedance.

Changing the tap to -6 dB would give 1/10 + 1/64 = 1/0.1156 = 8.65. Doubling the impedance of the driver only raised the total impedance 1 ohm (14%).

Now, for the voice coil inductance "problem". Most crossover designs do not consider the voice coil inductance because they are designed to "see" an impedance equal to the complex (mathmatically) sum of voice coil resistance + inductance. Al has chosen to model the 2 parts seperately. His computer program can do that. It would be quite difficult to do that by hand. It might be more accurate, but is considered unnecessary, especially in low order networks. It is hard to speak of accuracy and 6 dB crossovers in the same sentence. Either method considers the inductance, but does it differently.

Thanks John, this is a easy to follow explanation. I wish I had written it.

[seti]

Do you have testing equipment a mic rta software and a laptop? I hope so with all that speaker building you do. You could always get some parts together and do some crossover experiments on just a single driver that could be verified through measurements. That could lead to some answers or maybe even more questions.

I desperately need to find someone to help me design and test speakers. I've been trying to hook up with someone for almost two years now. I even flew to Toronto Canada one time to meet with someone I thought might be a good candidate. It didn't turn out. I've spent time on hundreds of emails with people who I thought might be able to work with, but nothing has worked out yet. One VERY qualified person expressed interest, but the cost per hour was very high for me, and there was no telling how much time we would spend on even just one design, so I didn't think I could do that right now.

I don't want someone to teach me, I want someone to work with me directly. With electronic communications the way they are these days, there's no reason why I can't partner with someone to test speakers in my shop in Benton Maine, while they are located wherever in the world.

Not having someone to work with on a technical level is really holding me up on a lot of things. Right now I'm only able to develop known ideas or to change things aesthetically, or to market myself and my products.

I'm not going to learn the technical aspects of speaker design. My brain just can't wrap itself around those concepts. I've tried, it just ain't happenin! Not in this lifetime anyway. But I shouldn't have to, there's plenty of people out there capable of doing that work. I need to concentrate on the things that I do well and subcontract those that I don't. It's harder than you think to find someone though. Some generous souls from this forum have tried to help me and I have a way of tiring them out I think! LOL Since the emails slow down and stop after some time. LOL It is hard to do.

Greg

I was about to suggest someone but after looking at their rates it could get very expensive. I hope you find someone. Good luck!

[greg928gts]

Here's a new set I just built with Sonicaps. Haven't listened to them yet.

Greg

[JohnA]

Are you still building the Super A for people to use?

I haven't built or sold any of these filter types for some time.

The reason I ask is because I want to be able to offer different choices to my customers when they decide to upgrade their Khorns. Right now I can offer them Universal networks that I'm building from kits (I have an agreement with Al on this), I have my new VSi networks, and then Al is working on the ES300 for the V-Trac. But one more network design would be nice. Something between the VSi and the Universal in terms of complexity.

One thing I don't understand is the 2.4mhy inductor shown in the DHA schematic. The Universal uses a 1.3mhy. Don't both cross the woofer at 400Hz?

Greg

The ALKs I have have a 2.4 mH woofer inductor.

[Guest David H]

The ALKs I have have a 2.4 mH woofer inductor.

The early ALK Universals used a 2.4mH inductor with a 41uF cap on the mids, later changed to a 1.3mH and a 48uF.