Its complicated, and the answer is "it all depends". IF the wave on both sides of the edge of this slit is in phase and of the same amplitude then no there is no diffraction as there is no discontinuity of the wavefront. But, in virtually all phase plugs, this cannot be the case. The phase of the wavefront is usually made to be continuous across this boundary, BUT the amplitude is not controlled as such and the prevailing design philosophy guarantees that the amplitude in each channel will be different.
I can only hypothesize as the the level and significance of this effect. In any driver/waveguide combination where extensive care has not been taken to control the HOM, the effect of this aberation would be negiligable in comparison to the other sources of HOM. But in one where extreme attention has been paid to a continuity of both area and wall slope (as I do), it would be the largest remaining source of HOM in the system at this point, i.e. the junction aperature. Sorting this out in detail has always been a desire of mine and I know how to make the measurements and do the tests, but alas, I lack the resources to pursue it any further.
John - Lidia and my study was not about phase plugs per-se but about the general audibility of an HOM type of aberation in the signal path. Nothing so specific as to the sources of these aberations was done as it was a rough test intended only to find the order of magnitude of the audibility of such aberations.
I can only hypothesize as the the level and significance of this effect. In any driver/waveguide combination where extensive care has not been taken to control the HOM, the effect of this aberation would be negiligable in comparison to the other sources of HOM. But in one where extreme attention has been paid to a continuity of both area and wall slope (as I do), it would be the largest remaining source of HOM in the system at this point, i.e. the junction aperature. Sorting this out in detail has always been a desire of mine and I know how to make the measurements and do the tests, but alas, I lack the resources to pursue it any further.
John - Lidia and my study was not about phase plugs per-se but about the general audibility of an HOM type of aberation in the signal path. Nothing so specific as to the sources of these aberations was done as it was a rough test intended only to find the order of magnitude of the audibility of such aberations.
I started assembling my speakers. They went together pretty good on the dry fit. The only problem was a gap between the front baffle and sides that was a tiny bit too large to fill up with glue. I'm filling it with a veneer shim.
Things are going slowly - I'm very busy at work for a few more weeks.
BTW, the Assembly Manual I received is quite explicit about how the CD should be mounted and it follows what Earl posted today and has posted many times elsewhere.
I've used the modeling clay for damping and smoothing edges of plastic horns/waveguides and it works just great and is probably the best and cheapest damping material you can find. It's very dense and is a truly lousy sound conductor.
Things are going slowly - I'm very busy at work for a few more weeks.
BTW, the Assembly Manual I received is quite explicit about how the CD should be mounted and it follows what Earl posted today and has posted many times elsewhere.
I've used the modeling clay for damping and smoothing edges of plastic horns/waveguides and it works just great and is probably the best and cheapest damping material you can find. It's very dense and is a truly lousy sound conductor.
Hi,
I have been following this thread and am interested in buying and building one of the kits.
The information here will be really helpful and it does work as a beta test of sorts for us others who have not started yet.
Also most interesting will be to hear what the listening impressions will be once some of you builders have completed the kits.
Thanks,
//rené
I have been following this thread and am interested in buying and building one of the kits.
The information here will be really helpful and it does work as a beta test of sorts for us others who have not started yet.
Also most interesting will be to hear what the listening impressions will be once some of you builders have completed the kits.
Thanks,
//rené
Listening impressions of my larger Summas are on my website, so I'll refer to those as my base of comparison. I have had the Nathans in my theater now for several weeks. They are not Summas, but they are very close. It's like a violin versus a Stradivarius violin. The differences are not huge, they both work well, but that finite level of improvement takes a lot of effort.
At any rate, I am very pleased with the Natahns in the end. They are definately something that I am proud to put my name on (actually my sons name, but he didn't get a choice).
At any rate, I am very pleased with the Natahns in the end. They are definately something that I am proud to put my name on (actually my sons name, but he didn't get a choice).
Final assembly!
You have to run two wires to connect two sections of the crossover.
Screw in the terminals. Use a short piece of wire to connect the crossover and the terminals and solder them. Besides soldering in one cap that's all soldering that has to be done.
Then run the wires (Wire not thicker 1.5 mm² works best - for optimal durability use ferrules at the cable ends) from tweeter and woofer to the crossover:
Throw in the damping. Placing it in the middle of the enclosure has the best effect. Don't block any openings of the woofer:
Glue in the foam plug. If you're using glue spray as Earl recommends then be very careful not to spray into the compression drivers throat. Best is to cover it with tape temporarily.
We're done:
Best, Markus
You have to run two wires to connect two sections of the crossover.
Screw in the terminals. Use a short piece of wire to connect the crossover and the terminals and solder them. Besides soldering in one cap that's all soldering that has to be done.
An externally hosted image should be here but it was not working when we last tested it.
Then run the wires (Wire not thicker 1.5 mm² works best - for optimal durability use ferrules at the cable ends) from tweeter and woofer to the crossover:
An externally hosted image should be here but it was not working when we last tested it.
Throw in the damping. Placing it in the middle of the enclosure has the best effect. Don't block any openings of the woofer:
An externally hosted image should be here but it was not working when we last tested it.
Glue in the foam plug. If you're using glue spray as Earl recommends then be very careful not to spray into the compression drivers throat. Best is to cover it with tape temporarily.
We're done:
An externally hosted image should be here but it was not working when we last tested it.
Best, Markus
Markus
Not bad! Good work and thanks for the posts. You have been a great help in "debugging" the kit and I appreciate it.
Did you like the screw terminals for the crossover? I have found them very effective, especially given my disdain for solder. I've never seen the need for ferules at the wire ends though.
I put the circular cut foam around the woofer, precisely what you say not to do. I'm trying to stop sound from coming back through the cone. This material is so porous that its affect on the LFs of the woofer will be negligable. Some absorption at the tweeter end is fine, but a lot of absorption is not really required, although it won't hurt either. Stuffing the box might drop the LF limit maybe 10 Hz. if that desired. In that case I'd just use fiberglass in addition to all the foam that comes in the shipment.
But I really would put the foam piece arround the woofer basket. Thats what it is intended to do (need to put that in the manual too.)
Oh yea, I spray the plug, not the enclosure when I glue in the foam. There is no risk of glue in the throat.
Did you feel the throat for any mismatches? Your finger can feel what your eyes can't see. If it is significant it will feel like a cavern. Then simply smooth some of the dreeded clay to get a smooth transition from the driver to the waveguide. You could use your vynle here also I suppose.
At any rate - good job. Thanks again.
Not bad! Good work and thanks for the posts. You have been a great help in "debugging" the kit and I appreciate it.
Did you like the screw terminals for the crossover? I have found them very effective, especially given my disdain for solder. I've never seen the need for ferules at the wire ends though.
I put the circular cut foam around the woofer, precisely what you say not to do. I'm trying to stop sound from coming back through the cone. This material is so porous that its affect on the LFs of the woofer will be negligable. Some absorption at the tweeter end is fine, but a lot of absorption is not really required, although it won't hurt either. Stuffing the box might drop the LF limit maybe 10 Hz. if that desired. In that case I'd just use fiberglass in addition to all the foam that comes in the shipment.
But I really would put the foam piece arround the woofer basket. Thats what it is intended to do (need to put that in the manual too.)
Oh yea, I spray the plug, not the enclosure when I glue in the foam. There is no risk of glue in the throat.
Did you feel the throat for any mismatches? Your finger can feel what your eyes can't see. If it is significant it will feel like a cavern. Then simply smooth some of the dreeded clay to get a smooth transition from the driver to the waveguide. You could use your vynle here also I suppose.
At any rate - good job. Thanks again.
Some German guys did an empirical test with damping at different positions within the enclosure. And placing good old fiberglass in the middle of the enclosure had the best effect on standing waves. Maybe you have more data on that available?
Regarding clay vs. caulk: The stuff I used did shrink. So you will have to apply a second coat.
Best, Markus
Regarding clay vs. caulk: The stuff I used did shrink. So you will have to apply a second coat.
Best, Markus
Summary
It was fun building the speakers although I had to build them in our apartment with a limited range of tools. This is what I consider the absolut minimum tools you need to built this kit and probably any other kit that comes with pre cut boards and routed cut-outs for the drivers:
My expectations were very high because the vendor claimed that the whole concept of the speaker is superior to what is available on the market today. So I was very disappointed that the quality of the wooden parts were not near to that of other kits.
Furthermore I was not aware that the kit was still in development. Crucial parts were missing: screws, jumper for the crossover, internal wiring, gasket for mounting plate and driver, clay.
The vendor said to have fixed all these issues. Wooden parts are now cut on a CNC machine.
I recommend the kit only to experienced DIYers. This kit is not just a simple assembly of pre-painted boards, drivers and crossover. You have to build the crossover yourself. You have to drill holes. You have to treat the tweeter. And you have to apply some kind of finish to the enclosure.
If you don't have the skills to do that then I recommend buying the pre-built speakers offered by the vendor. They are a real bargain. Take into account that you have to add the price for all the tools and materials shown in the picture above to the kits cost.
The vendor was very responsive. Earl responded to emails within minutes. This is highly appreciated.
But now on to finishing the subwoofers as the Nathan 10 is not a full range speaker but part of a satellite/subwoofer concept:
Best, Markus
It was fun building the speakers although I had to build them in our apartment with a limited range of tools. This is what I consider the absolut minimum tools you need to built this kit and probably any other kit that comes with pre cut boards and routed cut-outs for the drivers:
An externally hosted image should be here but it was not working when we last tested it.
My expectations were very high because the vendor claimed that the whole concept of the speaker is superior to what is available on the market today. So I was very disappointed that the quality of the wooden parts were not near to that of other kits.
Furthermore I was not aware that the kit was still in development. Crucial parts were missing: screws, jumper for the crossover, internal wiring, gasket for mounting plate and driver, clay.
The vendor said to have fixed all these issues. Wooden parts are now cut on a CNC machine.
I recommend the kit only to experienced DIYers. This kit is not just a simple assembly of pre-painted boards, drivers and crossover. You have to build the crossover yourself. You have to drill holes. You have to treat the tweeter. And you have to apply some kind of finish to the enclosure.
If you don't have the skills to do that then I recommend buying the pre-built speakers offered by the vendor. They are a real bargain. Take into account that you have to add the price for all the tools and materials shown in the picture above to the kits cost.
The vendor was very responsive. Earl responded to emails within minutes. This is highly appreciated.
But now on to finishing the subwoofers as the Nathan 10 is not a full range speaker but part of a satellite/subwoofer concept:
An externally hosted image should be here but it was not working when we last tested it.
Best, Markus
Bravo Markus. You are both competent, informative, just, and sincere.
I wish that your soon to be complete system will stand up to your expectations. I personally like the color you chose. We reasonably all wait for your subjective review when you are ready, set, and have spent enough listening hours on your new system. The multi sub tuning procedure will be very interesting to report too. I am sure that Dr. G. will be helping out as always.
I wish that your soon to be complete system will stand up to your expectations. I personally like the color you chose. We reasonably all wait for your subjective review when you are ready, set, and have spent enough listening hours on your new system. The multi sub tuning procedure will be very interesting to report too. I am sure that Dr. G. will be helping out as always.
"Some German guys did an empirical test with damping at different positions within the enclosure. And placing good old fiberglass in the middle of the enclosure had the best effect on standing waves. Maybe you have more data on that available?"
Standing waves are a subset of all of the sound reflecting around inside the box; I agree with Dr. Geddes that it's most important to keep it from transmitting through the woofer cone.
But you don't have to choose one or the other; as Dr. Geddes said, just fill the entire box w/damping material.
Standing waves are a subset of all of the sound reflecting around inside the box; I agree with Dr. Geddes that it's most important to keep it from transmitting through the woofer cone.
But you don't have to choose one or the other; as Dr. Geddes said, just fill the entire box w/damping material.
markus76 said:
For damping interior standing waves that is certainly true, but, as I said, my intent was not to dampen internal resonances but to reduce the sound coming back through the cone. I have never been convinced that enclosure resonances either interior or structural are major effects once some simple techniques to reduce them have been employed.
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