I must be crazy.
I have been reading this forum for a while and have even built a pair of pretty nice two-ways using the Dayton 8” driver (295-310) and silk dome tweeter (275-070). I used Dave Tenney’s MT design and crossover. I like them a lot.
I became intrigued by the concept of the line array after reading about it and have done quite a bit of research before even considering posting here about it. I ruminated on the possibility of building a pair for a long time. I must have come to the conclusion that I thought it might be a good idea to build them because the parts arrive today via UPS from PartsExpress. This one is going to send the wife over the edge. I may be sleeping on the couch tonight even though the cost was not that significant ($76 including shipping).
I have ordered 40 of the NSB midrange drivers by Pioneer (269-568) and 50 of the Onkyo tweeters (269-702) with the intention of building a 16/24 array wired for an 8 ohm load.
I have read everything I can find on these drivers on this forum using as many search parameters as I could think of. I have a bunch of questions that I would like some help with if some of you are willing to stick with me on this project. I will try to parse them out into digestible chunks so that I don’t get confused.
First Question: What about a box instead of an open baffle? I’ve been messing with WinISD a little and it looks like if you make a ported box you can get reasonably good bass response that extends to 50 Hz. That should not be right because the Fs of the NSB is 106 Hz. It shouldn’t sound that good right? Additionally in modeling a ported box the port length and diameter are actually almost as big as the box itself. Has anybody done this and if so what are your results?
I’m inclined to go open baffle because it will be slightly easier and more of a challenge to build with a high WAF (should be fun if I’m already sleeping on the couch…). However if someone has the right box and it makes the crossover easier and cheaper, I would go with that.
It turns out that most of my questions relate to CROSSOVERS, BAFFLE STEP CORRECTION and BAFFLE SIZE
Second question: What about a crossover? I remember reading a thread in which sreten recommended a first order low pass at 600 Hz and a second order high pass at 5000 Hz. His recommendation was an economical one keeping in mind that you could spend a lot on the crossover but that doing so would defeat the purpose of the project which is to build something that is inexpensive and sounds good.
I will be removing the on-board crossover and the phase shield of the tweeter and from the frequency response graph provided by PartsExpress the 5000 Hz high pass makes sense.
I’m less comfortable with the low pass portion. Especially in the context of an open baffle configuration.
Third question: Will crossing first order at 600 Hz not create a noticeable dip in the upper midrange such that it won’t sound very good? 600 Hz seems a little high for baffle step correction, and a little low for achieving a reasonably flat frequency response.
Fourth question: Has anyone designed an inexpensive low pass for this driver that will work well with this tweeter and that has some measure of baffle step correction in it?
Fifth question: How do I build the circuit described in The Edge? I’ve used The Edge simulator to model the baffle size, driver placement, and the overall baffle step loss. I realize it’s not perfect, but it gives me pretty graphs to work with. One of the options is to design a circuit for “Open baffle bass drop compensation”. For those of you who have used The Edge and who know how to read a circuit, how do I wire the components up? The triangle is an amplifier, right? R2 and C are in Parallel with respect to each other and in series with R1. What is R1? Why are there two of them?
Sixth Question: What about an L-pad for the 16/24 configuration? Because these drivers are of virtually the same sensitivity won’t the tweeters need to be attenuated approximately 4 dB? Is that right?
OTHER TOPICS
Seventh Question: Has anyone tried coating the 4” Pioneer drivers with any kind of material to smooth out the response a little? There has been discussion of diluted Elmer’s glue and Dammar varnish that made some sense. The problem with those I have discovered after doing my homework is that both will dry brittle. I remember reading (and it makes sense intuitively) that the coating should provide stiffening but should remain flexible. Given all of this has anybody considered high quality shellac? I understand that shellac dries flexible and remains so. What do you think?
If you’ve stuck with me this far you know for sure that I’m nuts and probably ought to be locked up.
Thank you for your time.
I have been reading this forum for a while and have even built a pair of pretty nice two-ways using the Dayton 8” driver (295-310) and silk dome tweeter (275-070). I used Dave Tenney’s MT design and crossover. I like them a lot.
I became intrigued by the concept of the line array after reading about it and have done quite a bit of research before even considering posting here about it. I ruminated on the possibility of building a pair for a long time. I must have come to the conclusion that I thought it might be a good idea to build them because the parts arrive today via UPS from PartsExpress. This one is going to send the wife over the edge. I may be sleeping on the couch tonight even though the cost was not that significant ($76 including shipping).
I have ordered 40 of the NSB midrange drivers by Pioneer (269-568) and 50 of the Onkyo tweeters (269-702) with the intention of building a 16/24 array wired for an 8 ohm load.
I have read everything I can find on these drivers on this forum using as many search parameters as I could think of. I have a bunch of questions that I would like some help with if some of you are willing to stick with me on this project. I will try to parse them out into digestible chunks so that I don’t get confused.
First Question: What about a box instead of an open baffle? I’ve been messing with WinISD a little and it looks like if you make a ported box you can get reasonably good bass response that extends to 50 Hz. That should not be right because the Fs of the NSB is 106 Hz. It shouldn’t sound that good right? Additionally in modeling a ported box the port length and diameter are actually almost as big as the box itself. Has anybody done this and if so what are your results?
I’m inclined to go open baffle because it will be slightly easier and more of a challenge to build with a high WAF (should be fun if I’m already sleeping on the couch…). However if someone has the right box and it makes the crossover easier and cheaper, I would go with that.
It turns out that most of my questions relate to CROSSOVERS, BAFFLE STEP CORRECTION and BAFFLE SIZE
Second question: What about a crossover? I remember reading a thread in which sreten recommended a first order low pass at 600 Hz and a second order high pass at 5000 Hz. His recommendation was an economical one keeping in mind that you could spend a lot on the crossover but that doing so would defeat the purpose of the project which is to build something that is inexpensive and sounds good.
I will be removing the on-board crossover and the phase shield of the tweeter and from the frequency response graph provided by PartsExpress the 5000 Hz high pass makes sense.
I’m less comfortable with the low pass portion. Especially in the context of an open baffle configuration.
Third question: Will crossing first order at 600 Hz not create a noticeable dip in the upper midrange such that it won’t sound very good? 600 Hz seems a little high for baffle step correction, and a little low for achieving a reasonably flat frequency response.
Fourth question: Has anyone designed an inexpensive low pass for this driver that will work well with this tweeter and that has some measure of baffle step correction in it?
Fifth question: How do I build the circuit described in The Edge? I’ve used The Edge simulator to model the baffle size, driver placement, and the overall baffle step loss. I realize it’s not perfect, but it gives me pretty graphs to work with. One of the options is to design a circuit for “Open baffle bass drop compensation”. For those of you who have used The Edge and who know how to read a circuit, how do I wire the components up? The triangle is an amplifier, right? R2 and C are in Parallel with respect to each other and in series with R1. What is R1? Why are there two of them?
Sixth Question: What about an L-pad for the 16/24 configuration? Because these drivers are of virtually the same sensitivity won’t the tweeters need to be attenuated approximately 4 dB? Is that right?
OTHER TOPICS
Seventh Question: Has anyone tried coating the 4” Pioneer drivers with any kind of material to smooth out the response a little? There has been discussion of diluted Elmer’s glue and Dammar varnish that made some sense. The problem with those I have discovered after doing my homework is that both will dry brittle. I remember reading (and it makes sense intuitively) that the coating should provide stiffening but should remain flexible. Given all of this has anybody considered high quality shellac? I understand that shellac dries flexible and remains so. What do you think?
If you’ve stuck with me this far you know for sure that I’m nuts and probably ought to be locked up.
Thank you for your time.
Generally..
Avoid ported enclosures..
Remember that midrange line will be dramatically boosted below 1kHz.
notice the difference here:
http://www.partsexpress.com/projectshowcase/Kuze3201/Kuze3201.html
Don't expect to do this with a reasonably flat freq. response without measuring equipment. Speaker workshop is free but you'll have to make your own jig and mic (which is the reason I purchased the speakerlab mic and software combo).
edit: oops.. thats loudspeakerlab - located here:
http://www.wavecapture.com/
(but it doesn't appear that they sell with a mic anymore..)
Avoid ported enclosures..
Remember that midrange line will be dramatically boosted below 1kHz.
notice the difference here:
http://www.partsexpress.com/projectshowcase/Kuze3201/Kuze3201.html
Don't expect to do this with a reasonably flat freq. response without measuring equipment. Speaker workshop is free but you'll have to make your own jig and mic (which is the reason I purchased the speakerlab mic and software combo).
edit: oops.. thats loudspeakerlab - located here:
http://www.wavecapture.com/
(but it doesn't appear that they sell with a mic anymore..)
I, too, would LOVE an answer to these questions, or multiple answers 🙂
I'm in the same boat as you, cytokine. I have 96 of the Pioneers and 128 of the Onkyos just in case my brothers want a pair!
I'm in the same boat as you, cytokine. I have 96 of the Pioneers and 128 of the Onkyos just in case my brothers want a pair!
Scott:
Thanks for reminding me of that Tang Band line. I had seen that and I still think it looks sweet. It got me thinking about Tangs for a later array if I can get this one to work well.
Mazeroth:
Let's do this together and see if we can add to the knowledge base of the forum on these critters.
I said I had searched a lot for info on these drivers and line arrays, and I do mean a lot. I'm pretty sure I've seen everything out there. Maybe not though. Today I learned that the NSB drivers might have been made for Sony TVs.
Here's my latest thinking on the low pass portion of the crossover. There will be no impedence EQ in the crossover circuit. Therefore, if I understand correctly, as frequency rises and impedence rises (see the impedence plot for details) the crossover will become less effective. Thus a first order low pass at around 600 Hz may have the effect of smoothing that midbass hump between 300 and 1000 Hz, while it won't take as much off of the curve starting at around 2 kHz.
I haven't committed to a circuit yet and I'm thinking that if I'm going to try to smooth that hump I might want to low pass a little lower, say at 300 Hz. Maybe not. Like I said, I haven't decided.
As someone who has already built these has said elsewhere, to paraphrase: don't dwell on it, just build them and see what happens. In the true spirit of DIY that is what I will do.
As for coating the drivers I'm going to try and find the time during the day tomorrow to get some shellac to coat one of the extra NSBs with to see how that affects the sound.
I don't have any formal measuring equipment but I may get a mic and try to get Speakerworks working for this project.
Oh yes, let me not forget to thank Svante Graqnvist for The Edge baffle simulator and for answering my e-mails this afternoon. He's been very helpful, even with questions that reveal my woeful ignorance of electronics and electricity.
Svante suggests that I need a baffle as large as possible for an open baffle and NO compensation.
Live update: I arrived home to find three boxes on my porch this evening after work. One was quite large and very heavy. I assumed this to be the NSBs. One was quite small and I assumed this was the 8 mids that I ordered over and above the case quantity of 32. The last was quite compact but still large and not as heavy. This should have been the tweeters, right?
Nope. The tweeters were in the largest box and they are very heavy. They look pretty nice for the price and I'll start taking them apart tomorrow. The NSBs are actually built fairly solidly and look pretty good from the front except for the yellow colored face plate. I might make a jig to cover the cone and paint the face plates flat black.
Final thought. It looks like I get to sleep in my own bed tonight. The wife is a wonderfully forebearing soul and was more surprised that the whole load only cost $75, than that I was making them. She's a peach.
Last thing. I think I may just go ahead and cross over as sreten suggested with the low pass at 600 Hz first order and see how it sounds.
I'll keep you posted. This will take some time.
Thanks for reminding me of that Tang Band line. I had seen that and I still think it looks sweet. It got me thinking about Tangs for a later array if I can get this one to work well.
Mazeroth:
Let's do this together and see if we can add to the knowledge base of the forum on these critters.
I said I had searched a lot for info on these drivers and line arrays, and I do mean a lot. I'm pretty sure I've seen everything out there. Maybe not though. Today I learned that the NSB drivers might have been made for Sony TVs.
Here's my latest thinking on the low pass portion of the crossover. There will be no impedence EQ in the crossover circuit. Therefore, if I understand correctly, as frequency rises and impedence rises (see the impedence plot for details) the crossover will become less effective. Thus a first order low pass at around 600 Hz may have the effect of smoothing that midbass hump between 300 and 1000 Hz, while it won't take as much off of the curve starting at around 2 kHz.
I haven't committed to a circuit yet and I'm thinking that if I'm going to try to smooth that hump I might want to low pass a little lower, say at 300 Hz. Maybe not. Like I said, I haven't decided.
As someone who has already built these has said elsewhere, to paraphrase: don't dwell on it, just build them and see what happens. In the true spirit of DIY that is what I will do.
As for coating the drivers I'm going to try and find the time during the day tomorrow to get some shellac to coat one of the extra NSBs with to see how that affects the sound.
I don't have any formal measuring equipment but I may get a mic and try to get Speakerworks working for this project.
Oh yes, let me not forget to thank Svante Graqnvist for The Edge baffle simulator and for answering my e-mails this afternoon. He's been very helpful, even with questions that reveal my woeful ignorance of electronics and electricity.
Svante suggests that I need a baffle as large as possible for an open baffle and NO compensation.
Live update: I arrived home to find three boxes on my porch this evening after work. One was quite large and very heavy. I assumed this to be the NSBs. One was quite small and I assumed this was the 8 mids that I ordered over and above the case quantity of 32. The last was quite compact but still large and not as heavy. This should have been the tweeters, right?
Nope. The tweeters were in the largest box and they are very heavy. They look pretty nice for the price and I'll start taking them apart tomorrow. The NSBs are actually built fairly solidly and look pretty good from the front except for the yellow colored face plate. I might make a jig to cover the cone and paint the face plates flat black.
Final thought. It looks like I get to sleep in my own bed tonight. The wife is a wonderfully forebearing soul and was more surprised that the whole load only cost $75, than that I was making them. She's a peach.
Last thing. I think I may just go ahead and cross over as sreten suggested with the low pass at 600 Hz first order and see how it sounds.
I'll keep you posted. This will take some time.
Here's a project that might interest you if you haven't already seen it:
open baffle line array speakers with fullrange drivers
Open baffle does sound very promising - why not give it a go. If you do this, then I'd pick a point where you want to cross to subs or bi-amped woofers and make the baffle wide enough so that there is no dipole cancellation in the range you are using them. This is something you need to experiment with.
It's not a good idea to use drivers much below their fs.
I dont' believe vented boxes are evil! You can get a vented alignment to be more linear due to decreased cone excursion. You could tune a vented alignment at fs and roll off the bass with a steep slope where you cross to a sub. Trying to do this with a sealed alignment may mean you will have a lot of rolloff before 100 hz and hence a dip where you cross to your subs.
2 options that stand out to me:
1. open baffle crossed fairly high at say 300 Hz to bi-amped woofers (and possibly subs if you want to go lower than 40 Hz)
2. vented tuned to fs at which point you cross to a sub - the highpass filter is critical to prevent overexcursion
open baffle line array speakers with fullrange drivers
An externally hosted image should be here but it was not working when we last tested it.
Open baffle does sound very promising - why not give it a go. If you do this, then I'd pick a point where you want to cross to subs or bi-amped woofers and make the baffle wide enough so that there is no dipole cancellation in the range you are using them. This is something you need to experiment with.
It's not a good idea to use drivers much below their fs.
I dont' believe vented boxes are evil! You can get a vented alignment to be more linear due to decreased cone excursion. You could tune a vented alignment at fs and roll off the bass with a steep slope where you cross to a sub. Trying to do this with a sealed alignment may mean you will have a lot of rolloff before 100 hz and hence a dip where you cross to your subs.
2 options that stand out to me:
1. open baffle crossed fairly high at say 300 Hz to bi-amped woofers (and possibly subs if you want to go lower than 40 Hz)
2. vented tuned to fs at which point you cross to a sub - the highpass filter is critical to prevent overexcursion
Paul;
Gorgeous! I'm going to have a close look at the link you sent me as soon as I have a moment.
I appreciate the suggestion about a vented enclosure. The problem I ran into with WinISD modeling 16 drivers was that the recommended size of the port was almost as large as the enclosure and the enclosure was smaller than the volume of the drivers. I must have done something wrong. Any suggestions?
For now, I stopped at the hardware store this morning on the way to work and didn't find shellac. Some store. I did pick up some rubber cement to try on some paper to see if it will dry non-tacky and flexible.
I then went to a craft store and found this:
Winsor and Newton Varnish
The Dammar didn't say anything about not cracking and this stuff did so I opted for this.
I appreciate all the help and I will be sure to share the results of my experiments because it seems like there are a lot of us who have yielded to the temptation of these little drivers.
Final thought: If coating the NSBs works and it takes out the 7 kHz on-axis peak then I may just run them full-range with no crossover and cross the tweeters as high as I can.
Gorgeous! I'm going to have a close look at the link you sent me as soon as I have a moment.
I appreciate the suggestion about a vented enclosure. The problem I ran into with WinISD modeling 16 drivers was that the recommended size of the port was almost as large as the enclosure and the enclosure was smaller than the volume of the drivers. I must have done something wrong. Any suggestions?
For now, I stopped at the hardware store this morning on the way to work and didn't find shellac. Some store. I did pick up some rubber cement to try on some paper to see if it will dry non-tacky and flexible.
I then went to a craft store and found this:
The Dammar didn't say anything about not cracking and this stuff did so I opted for this.
I appreciate all the help and I will be sure to share the results of my experiments because it seems like there are a lot of us who have yielded to the temptation of these little drivers.
Final thought: If coating the NSBs works and it takes out the 7 kHz on-axis peak then I may just run them full-range with no crossover and cross the tweeters as high as I can.
cytokine said:
Anyone looking for a budget tweeter shouldn't forget about the ApexJr tweeter. At 2 for a buck it certainly qualifies as a Frugal-phile(tm) kinda product. I have been very pleased with their performance... my 1st 50 went 1 pr at a time (mostly SuperTs for 40-1197), i may look at a LA for this batch of 50 i just got.
Tom (IIRC) used them in his LA (thread on this forum)
dave
Attachments
cytokine said:
A vent tuned at 100 hz should be small. Tell us the volume, tuning point and diameter of the vent and we can confirm if the vent length is correct.
Dave: Thanks for the suggestion about the ApexJr. tweeters. Have you heard the Onkyos? I would be interested in knowing whether one or the other sounds better and what the measurements on the ApexJr.s look like. The price is right.
Paul: I'll try to get back to WinISD and repeat my modeling tonight. I'm sure whatever error there is is probably mine. I'll let you know when I have some information for you.
Today's update is this:
I applied either one or two "coats" of varnish to the cones of two of the NSBs and likewise one or two "coats" of Elmer's rubber cement diluted 1:4 in mineral spirits. I put the word "coats" in quotes (sheer poetry...) because the paper of the cones is quite porous and the material absorbs immediately. This morning there is no obvious difference in the appearance of the four test drivers when compared to the control untreated driver.
I'm hoping to pop them into open baffles tonight to give them a listen.
It looks like I'm going to have to get a measuring microphone and fire up some testing software because the scientist in me (I really am a scientist) wants to know what the effect of these different treatments will be.
Paul: I'll try to get back to WinISD and repeat my modeling tonight. I'm sure whatever error there is is probably mine. I'll let you know when I have some information for you.
Today's update is this:
I applied either one or two "coats" of varnish to the cones of two of the NSBs and likewise one or two "coats" of Elmer's rubber cement diluted 1:4 in mineral spirits. I put the word "coats" in quotes (sheer poetry...) because the paper of the cones is quite porous and the material absorbs immediately. This morning there is no obvious difference in the appearance of the four test drivers when compared to the control untreated driver.
I'm hoping to pop them into open baffles tonight to give them a listen.
It looks like I'm going to have to get a measuring microphone and fire up some testing software because the scientist in me (I really am a scientist) wants to know what the effect of these different treatments will be.
You, sir, have done your homework.
Nice work and nice pictures. Thanks for sharing. I expecially like the phase plug.
So did you lay the coating on pretty thickly and did it really stiffen the cones, or is it pretty thin? As I think I said, the varnish and the Elmer's rubber cement seem to have completely sunk into the paper of the cone. I can't wait to get home to hear what impact these treatments have on the sound.
Have you tested each of these mods separately, or just all together? If separately, which has the most impact, the Mod Podge (that's a new one on me), the basked damping, or the phase plug?
I love the look of drivers with phase plugs. I presume there is a fair amount of effort that goes into designing and implementing a phase plug that helps the sound of a driver. What kind of difference does yours make?
Let's see now, one pair of line arrays with 16 drivers per side that need a phase plug. That's 32 bottles of wine. This project is getting better and better. Not only that but I want to complete this in real time. Let's see, I'll need some friends to help with the wine... Red or white?
Maybe I can get them at a craft store.
Nice work and nice pictures. Thanks for sharing. I expecially like the phase plug.
So did you lay the coating on pretty thickly and did it really stiffen the cones, or is it pretty thin? As I think I said, the varnish and the Elmer's rubber cement seem to have completely sunk into the paper of the cone. I can't wait to get home to hear what impact these treatments have on the sound.
Have you tested each of these mods separately, or just all together? If separately, which has the most impact, the Mod Podge (that's a new one on me), the basked damping, or the phase plug?
I love the look of drivers with phase plugs. I presume there is a fair amount of effort that goes into designing and implementing a phase plug that helps the sound of a driver. What kind of difference does yours make?
Let's see now, one pair of line arrays with 16 drivers per side that need a phase plug. That's 32 bottles of wine. This project is getting better and better. Not only that but I want to complete this in real time. Let's see, I'll need some friends to help with the wine... Red or white?
Maybe I can get them at a craft store.
cytokine said:
Haven't tried the Onkyo, it is in a similar class of tweeter. The ApexJr is cleaner looking, and you don't have to remove the cap to use it....
dave
Here's the latest: I cut two holes in a 2 x 4 sheet of 1/2" MDF and mounted a couple of the NSBs. These I hooked up to my old pioneer amp and an old 1 bit CD player. I fired up Jimmy Smith's 1995 offering entitled Damn! (if this get's censored it's the stronger version of Darn!). Nice work on the Hammond B3 organ for those of you who don't know Jimmy Smith.
My impressions: Damn! These things are pretty sound in the midrange. They have no bass. Zero. Zip. Nada. To my ear they roll off pretty hard starting at around 200 Hz and that is what the graph says.
On the high end they roll off pretty early and I'm not as good a judge of high notes as I am of the low end. I'll just say that I needed to hook up a couple of the Onkyo tweeters to hear the cymbals and the harmonics on the trumpets. Without the tweeters you can hear that 10 dB spike at 7 kHz pretty easily and it's not clean. It's some kind of cone resonance and it sounds pretty distorted. Off axis you don't hear it as much. With the tweeter, there's enough reinforcement at those frequencies for it to sound really god-awful if you forget for a second that you're listening to a pair of speakers that cost $1 each.
About halfway through Watermelon Man I pressed an old Yamaha bass reflex "subwoofer" into service and that balanced the sound pretty nicely. I had crap at the top, crap at the bottom and nice, punchy, clear midbass in between.
I'm making fun in the above review. I really am impressed with these mids and I think that once I figure out how to cross them over to the Onkyos they will sound nice. In the line array I expect them to absolutely slam in the midbass which is all I am really hoping for.
I still could use some help with the low pass end of the crossover. If anyone want's to offer a suggetion and a justification I'm all ears.
My impressions: Damn! These things are pretty sound in the midrange. They have no bass. Zero. Zip. Nada. To my ear they roll off pretty hard starting at around 200 Hz and that is what the graph says.
On the high end they roll off pretty early and I'm not as good a judge of high notes as I am of the low end. I'll just say that I needed to hook up a couple of the Onkyo tweeters to hear the cymbals and the harmonics on the trumpets. Without the tweeters you can hear that 10 dB spike at 7 kHz pretty easily and it's not clean. It's some kind of cone resonance and it sounds pretty distorted. Off axis you don't hear it as much. With the tweeter, there's enough reinforcement at those frequencies for it to sound really god-awful if you forget for a second that you're listening to a pair of speakers that cost $1 each.
About halfway through Watermelon Man I pressed an old Yamaha bass reflex "subwoofer" into service and that balanced the sound pretty nicely. I had crap at the top, crap at the bottom and nice, punchy, clear midbass in between.
I'm making fun in the above review. I really am impressed with these mids and I think that once I figure out how to cross them over to the Onkyos they will sound nice. In the line array I expect them to absolutely slam in the midbass which is all I am really hoping for.
I still could use some help with the low pass end of the crossover. If anyone want's to offer a suggetion and a justification I'm all ears.
After about one thin and one thick coat of PVA the Fs goes down to about 88Hz. When you remove the dust cap it goes back up to about 95Hz
Removing the dust cap will trim off some of the high end. If you dont want to make phase plugs dont cut off the whole dust cap. Insted just cut a small 1/8" hole to releave preasure between the cap and pole. there is a lot of space in there. Using a phase plug brought back the high end and gave better off axis sound--plus it looks cool.
The phase plugs where constructed by taking a screw and grabing it with the 'teeth' of my cordless drill. I took a cork and 'screwed' it on to the drill. This will give you a mini-lathe for sanding and shaping the cork to the shape you need. You want to make the plug a little smaller in diameter that the optimum. Several coats of PVA -sanding between coats- will smooth out the cork and damp it aswell. I painted mine with black paint and sanded. I spent way too much time making a cork phase plug for a $.69 speaker--but it was fun. After I painted and sanded a few times, I coated the plug again with a thinned PVA to make it really shine.
The PVA on the cone of the NSB does make them sound a lot smoother. But be carfull, too much PVA will kill the midrange that makes these things worth getting in the first place.
I am working on a blend of PVA and another thinner compound I will reveal later--if it works-- that you can get at any Wal-Mart. This other compound is as thin as whole milk and is very flexable when dry. I put way too much on one NSB thinking it had just soaked it up. Wasn't until I looked at the back of the cone and realized the stuff had just gone all the way through and dried on the back that I reallized how much I put on there. It now is a woofer, which leads to another though and question. If I load up one of these drivers with lots of Compound X and increace the mass, how effective would it be as a .5 woofer in a 2.5 way NSB/Onkyo speaker...or as the outter drivers in a 16 driver line array?
Removing the dust cap will trim off some of the high end. If you dont want to make phase plugs dont cut off the whole dust cap. Insted just cut a small 1/8" hole to releave preasure between the cap and pole. there is a lot of space in there. Using a phase plug brought back the high end and gave better off axis sound--plus it looks cool.
The phase plugs where constructed by taking a screw and grabing it with the 'teeth' of my cordless drill. I took a cork and 'screwed' it on to the drill. This will give you a mini-lathe for sanding and shaping the cork to the shape you need. You want to make the plug a little smaller in diameter that the optimum. Several coats of PVA -sanding between coats- will smooth out the cork and damp it aswell. I painted mine with black paint and sanded. I spent way too much time making a cork phase plug for a $.69 speaker--but it was fun. After I painted and sanded a few times, I coated the plug again with a thinned PVA to make it really shine.
The PVA on the cone of the NSB does make them sound a lot smoother. But be carfull, too much PVA will kill the midrange that makes these things worth getting in the first place.
I am working on a blend of PVA and another thinner compound I will reveal later--if it works-- that you can get at any Wal-Mart. This other compound is as thin as whole milk and is very flexable when dry. I put way too much on one NSB thinking it had just soaked it up. Wasn't until I looked at the back of the cone and realized the stuff had just gone all the way through and dried on the back that I reallized how much I put on there. It now is a woofer, which leads to another though and question. If I load up one of these drivers with lots of Compound X and increace the mass, how effective would it be as a .5 woofer in a 2.5 way NSB/Onkyo speaker...or as the outter drivers in a 16 driver line array?
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Sounds like PVA mixed with latex paint as compound X. I use red and blue food coloring as my PVA thinner which results in a darker shade of black on dark grey paper cones and looks much better than the yellowish result with just PVA.
Swirv,
Does PVA help at all with that nasty peak at 7khz? Regarding compounds, I'd think strength is what you want to add. I've gone with as much as 6 coats of thinned PVA front and back on woofers. This made the cone noticeably stiffer but wasn't brittle at all. Pushing at the edges to bend the cone never resulted in any cracks in the PVA.
Swirv,
Does PVA help at all with that nasty peak at 7khz? Regarding compounds, I'd think strength is what you want to add. I've gone with as much as 6 coats of thinned PVA front and back on woofers. This made the cone noticeably stiffer but wasn't brittle at all. Pushing at the edges to bend the cone never resulted in any cracks in the PVA.
The PVA Im using is Mod Podge. It dries and remains somewhat flexable. I imagine that if you thin wood glue (also PVA) and used it, that it would provide a stiffer result however, yellowish.
Compound X is actualy UV Killer a Ultra Violet blocking agent used on hunter's camoflage. It drys clear and is very thin. I mixed it with the Mod Podge and from what I can tell it makes the Mod Podge dry smoother and it may make it more flexable after drying.
My goal wasnt to stiffen the cone but to kill the "hollow" or "ringing" sounds of these drivers. I have not set up my measuring micorphone but they sound much better coated with Mod Podge.
As an experiment I coated a Coca Cola can with the mixture and let it dry. I hung it with some string and tapped it with my fingernail. I compared this to an untreated can to gadge results. The untreated can rings for a while after being struck. The treated can does not. The ring is shortened by a large margin. I imagin this is the effect the coating would have on an aluminium driver.
I agree with Dave D that the sandwich effect of layering pva/paper/pva would do a great deal to tame cone breakup.
Compound X is actualy UV Killer a Ultra Violet blocking agent used on hunter's camoflage. It drys clear and is very thin. I mixed it with the Mod Podge and from what I can tell it makes the Mod Podge dry smoother and it may make it more flexable after drying.
My goal wasnt to stiffen the cone but to kill the "hollow" or "ringing" sounds of these drivers. I have not set up my measuring micorphone but they sound much better coated with Mod Podge.
As an experiment I coated a Coca Cola can with the mixture and let it dry. I hung it with some string and tapped it with my fingernail. I compared this to an untreated can to gadge results. The untreated can rings for a while after being struck. The treated can does not. The ring is shortened by a large margin. I imagin this is the effect the coating would have on an aluminium driver.
I agree with Dave D that the sandwich effect of layering pva/paper/pva would do a great deal to tame cone breakup.
Hi Swirv, john;
I'm enjoying your discussion of the cone treatments. I spent the day routing 32 holes 3 5/8" in diameter for the mid line and routing out 1/2" of thickness behind where the tweeter line will go. I'm going to corner the market on MDF dust and I've let my neighbors in on the ground floor.
I've alluded to my design which I must share with you all soon but I don't have time now.
I just wanted to make two comments about the cone treatment. First, I am of the developing opinion that it won't much matter what you coat with as long as it stiffens enough to lower the Fs a little. Second, I noticed a difference with my two coats of 1:4 rubber cement:mineral spirits that was more impressive than the two coats of Winsor and Newton varnish. I think the reason for this is that the rubber cement cures very flexibly and has more bulk to it than the same volume of applied varnish.
I'm going to add a layer of rubber cement for a total of three to another driver and compare three coats to two. I think this will do the trick.
My overall impression was that the rubber cement improved the "bass" a little and seemed to lop off just enough of the top end of that 7 kHz peak to make the NSB smoother. It seemed to roll off at the top a little more smoothly, although I haven't measured it.
Final thought: What is the liklihood that treatment with these various solvent based products will weaken the joint between the paper cone and the rubber surround over time? This would be a bad thing. How is that joint made?
I'm enjoying your discussion of the cone treatments. I spent the day routing 32 holes 3 5/8" in diameter for the mid line and routing out 1/2" of thickness behind where the tweeter line will go. I'm going to corner the market on MDF dust and I've let my neighbors in on the ground floor.
I've alluded to my design which I must share with you all soon but I don't have time now.
I just wanted to make two comments about the cone treatment. First, I am of the developing opinion that it won't much matter what you coat with as long as it stiffens enough to lower the Fs a little. Second, I noticed a difference with my two coats of 1:4 rubber cement:mineral spirits that was more impressive than the two coats of Winsor and Newton varnish. I think the reason for this is that the rubber cement cures very flexibly and has more bulk to it than the same volume of applied varnish.
I'm going to add a layer of rubber cement for a total of three to another driver and compare three coats to two. I think this will do the trick.
My overall impression was that the rubber cement improved the "bass" a little and seemed to lop off just enough of the top end of that 7 kHz peak to make the NSB smoother. It seemed to roll off at the top a little more smoothly, although I haven't measured it.
Final thought: What is the liklihood that treatment with these various solvent based products will weaken the joint between the paper cone and the rubber surround over time? This would be a bad thing. How is that joint made?
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