Dr. Geddes, did you find that the respirator was letting stuff in? Using a decent pretty high end 3M mask I was finding black paint in my noise. I'm guessing it wasn't making it through the filters, but rather finding other ways in. I had it on as directed, tightened plenty tight, but I feel like it just didn't make a snug fit against my face. With those solvent based paints, I feel I would only be comfortable painting using a fresh air breathing system.
For me the 3M masks have worked fine, but they are known to not be great for solvents. But as I described my room is well ventilated. That and the mask seems to be fine. But I doubt that they would be OK in a sealed room.
I also have a high-end (turbine) HVLP that has very little overspray, which also helps a lot. The three things combined have yielded me no problems even with the worst solvent paints.
I also have a high-end (turbine) HVLP that has very little overspray, which also helps a lot. The three things combined have yielded me no problems even with the worst solvent paints.
Oh yeah, did you catch my question regarding the 1uf vs 1.47uf cap across the series resistor in the tweeter? What is the effect on the response again, I think I missed that discussion.
Matt
You can improve the axial response of your speakers as follows.
Delete the LRC with the 3 uF cap and the .6 mH inductor. This is used to improve the off axis response, but pulls down the axial hole a little (the two things are basically caused by the same mouth diffraction). Take that 3 uF cap and put it across the woofer LP cap, making this 38 uF. Then use the .47 in parallel to the 1 uF across the 10 ohm resistor. This will bring the center speakers on-axis to just about the +- 2 dB that is found at 22.5 degrees for the left and right speakers.
You may find the speaker too bright with the addition of the .47 cap, which can also be used on the LR speakers as well to bring up the 10 kHz range on those. But I've always found the system to be too bright when this is done. Its a direct versus power response thing and will depend on your room. There is no one right answer as to which is the "correct" way.
I'd evaluate the speakers as is for now and only change the crossover if you find a notable difference in the center channels from the other two.
You can improve the axial response of your speakers as follows.
Delete the LRC with the 3 uF cap and the .6 mH inductor. This is used to improve the off axis response, but pulls down the axial hole a little (the two things are basically caused by the same mouth diffraction). Take that 3 uF cap and put it across the woofer LP cap, making this 38 uF. Then use the .47 in parallel to the 1 uF across the 10 ohm resistor. This will bring the center speakers on-axis to just about the +- 2 dB that is found at 22.5 degrees for the left and right speakers.
You may find the speaker too bright with the addition of the .47 cap, which can also be used on the LR speakers as well to bring up the 10 kHz range on those. But I've always found the system to be too bright when this is done. Its a direct versus power response thing and will depend on your room. There is no one right answer as to which is the "correct" way.
I'd evaluate the speakers as is for now and only change the crossover if you find a notable difference in the center channels from the other two.
pjpoes said:
Check out what Mike Galusha made for his...
http://www.audiocircle.com/circles/index.php?topic=63956.msg582262#msg582262
He made a stand based on this
http://www.tnt-audio.com/clinica/stubby_e.html
Not sure if you are looking for aesthetic or practical value, and which side of the equation these fall on for you...
-Tony
The speakers are so big that I feel like a different style stand would be better. One like that or even the Bose stand I think will look funny on a speaker this big. Kind of like a fat man with tiny legs.
I won't make too much of this as I've just gotten the pair setup for all of 10 minutes, but so far I'm impressed with the sound stage. I played a couple parts of some tunes as well as HellBoy II which I have on now, and I noticed that they stage unlike other speakers I have heard. I need to listen to some soundstage test tracks to be sure of what I was hearing, but it's very much like the speakers disappear. I'm hoping to finish the center this weekend and take some measurements. I have electrical phase and impedance data, which looks decent enough. RE is 5.4 ohms, so nominal is more like 6ohms than 8 in the bass area, but more like 8 for most of the response. By using a 1khz test tone I tested a 2.83 volt spl of around 98db's, which I think is inline with what Dr. Geddes said.
Part of me really wants to turn it up right now and test these babies out, and part of me feels that Monday evening, my neighbor might not appreciate that. One of the things I read a lot of people say was that they produced sound effortlessly, making high spl's non-fatiguing. This is a quality I find very important in a speaker, but have almost never heard in anything I have owned. I can't make any concrete observations right now, just not enough experience, but the fact that I want to turn them up should say something.
Dr. Geddes, do I understand you correctly that the 1uf cap and 10 ohm resistor have less energy around 10khz than would the 1.47uf cap and 10 ohm resistor? I would not want any more energy up there I don't think. They sound well balanced, not warm by any means, not necessarily bright, but maybe if I had to choose a side, it would be the bright side of neutral.
I know that it makes the most sense to have the speakers at ear height, for a lot of reasons. However, my screen is higher than ear height, making the need for a high sound stage important. Probably makes sense to lower the screen. I had it so high because my 2 shelf rack unit and record player placed the center channel (which was at the bottom of the screen) just 10" below ear level. That means that my screen, which is 100"s is a bit too high. I have to move things around to handle such a big center channel, and I would like to redo things so that the center is behind the screen (changing to an acoustically transparent screen).
Hopefully by this weekend I will have pictures of everything finished and setup correctly. Also hopefully the rest of the parts will be here by then. I didn't have all the resistors I needed so I placed a few mills 4 ohm resistors I had around in place of the missing ones, so the lcr's are probably a bit lower Q than they are supposed to be. I also needed to order some parts from Parts Express for an hdtv install at a colleagues, so I ordered some of the sonic barrier foam, which I will install as further dampening.
I'm going to take some measurements this weekend. My method will average across roughly 60 degree's from on axis at 2 meters. I'll also take some measurements of the cabinet. I built the cabinet pretty much as directed. I didn't add any extra bracing or dampening (yet), so I will use this to get some baseline enclosure data.
I won't make too much of this as I've just gotten the pair setup for all of 10 minutes, but so far I'm impressed with the sound stage. I played a couple parts of some tunes as well as HellBoy II which I have on now, and I noticed that they stage unlike other speakers I have heard. I need to listen to some soundstage test tracks to be sure of what I was hearing, but it's very much like the speakers disappear. I'm hoping to finish the center this weekend and take some measurements. I have electrical phase and impedance data, which looks decent enough. RE is 5.4 ohms, so nominal is more like 6ohms than 8 in the bass area, but more like 8 for most of the response. By using a 1khz test tone I tested a 2.83 volt spl of around 98db's, which I think is inline with what Dr. Geddes said.
Part of me really wants to turn it up right now and test these babies out, and part of me feels that Monday evening, my neighbor might not appreciate that. One of the things I read a lot of people say was that they produced sound effortlessly, making high spl's non-fatiguing. This is a quality I find very important in a speaker, but have almost never heard in anything I have owned. I can't make any concrete observations right now, just not enough experience, but the fact that I want to turn them up should say something.
Dr. Geddes, do I understand you correctly that the 1uf cap and 10 ohm resistor have less energy around 10khz than would the 1.47uf cap and 10 ohm resistor? I would not want any more energy up there I don't think. They sound well balanced, not warm by any means, not necessarily bright, but maybe if I had to choose a side, it would be the bright side of neutral.
I know that it makes the most sense to have the speakers at ear height, for a lot of reasons. However, my screen is higher than ear height, making the need for a high sound stage important. Probably makes sense to lower the screen. I had it so high because my 2 shelf rack unit and record player placed the center channel (which was at the bottom of the screen) just 10" below ear level. That means that my screen, which is 100"s is a bit too high. I have to move things around to handle such a big center channel, and I would like to redo things so that the center is behind the screen (changing to an acoustically transparent screen).
Hopefully by this weekend I will have pictures of everything finished and setup correctly. Also hopefully the rest of the parts will be here by then. I didn't have all the resistors I needed so I placed a few mills 4 ohm resistors I had around in place of the missing ones, so the lcr's are probably a bit lower Q than they are supposed to be. I also needed to order some parts from Parts Express for an hdtv install at a colleagues, so I ordered some of the sonic barrier foam, which I will install as further dampening.
I'm going to take some measurements this weekend. My method will average across roughly 60 degree's from on axis at 2 meters. I'll also take some measurements of the cabinet. I built the cabinet pretty much as directed. I didn't add any extra bracing or dampening (yet), so I will use this to get some baseline enclosure data.
Congrats on your success!
Personally I intend to use a pedestal stand, like a solid block.
Curious though -what kind of measurements can you make on the cabinent?
-Tony
Personally I intend to use a pedestal stand, like a solid block.
Curious though -what kind of measurements can you make on the cabinent?
-Tony
I have a "surface mic" accelerometer that allows me to take measurements of the cabinet vibrations. By using a test signal and normal response measurement it shows resonance issues and area's where the cabinet is letting too much energy through. It will show up as a peak. By using a different type of measurement known as CSD, you can see how well dampened the cabinet is. However, I've had issues with CSD measurements in the past, and mostly use a non-decay type. I've also read a few articles that seem to indicate that CSD cabinet measurements aren't necessarily the end all for cabinet measurements, that the rate of decay doesn't tell you a lot. I think it seems like a sensible measurment, so if I could get a reliable CSD I would use it more. Some people feel that cabinets should evacuate energy quickly and efficiently. These, mostly brittish, speaker designers usually have thinner cabinets which show a lot of energy initially, but they claim, quick decay. Based on stereophiles measurements of these speakers, I think this isn't so, and I've noticed that many of these companies have begun using better braced and more solidly build cabinets.
The things I look for are matches between frequency peaks in the cabinet and impedance anomalies. This is a sure sign that there is a resonance causing an audible effect. Beyond that there isn't much to worry about.
It's very very hard to get good acoustical phase data in a room rather than an anechoic chamber, but I will try to capture that too. I'm really curious how smooth the phase response is of this design as compared with others I've measured or built myself. The electrical phase seems pretty nice, flat from around 1200hz on up.
The things I look for are matches between frequency peaks in the cabinet and impedance anomalies. This is a sure sign that there is a resonance causing an audible effect. Beyond that there isn't much to worry about.
It's very very hard to get good acoustical phase data in a room rather than an anechoic chamber, but I will try to capture that too. I'm really curious how smooth the phase response is of this design as compared with others I've measured or built myself. The electrical phase seems pretty nice, flat from around 1200hz on up.
pjpoes said:
Exactly my feelings too, but to be accurate the response is flatter above 8 kHz with 1.47 than with 1.0. But the power response up that high is way beyond anything that you are likely to have heard before - its turuey CD, not beamy like a dome - so thats why (I think) they are perceived as being bright.
pjpoes said:
The problem with surface measurements is that they don't correlate with the sound that is actually radiated. For example a high vibration on one panel will radiate very effectively if the opposite panel is also vibrating at this same frquency and in phase, but will radiate very little if they are out of phase. Thus just looking at any one panel doesn't tell the whole story. And in fact you can't say much at all from a vibration measurement other than "Yep, there's a vibration there." Can you hear it? Not a clue.
I design my cabinets and the structural supports to minimize the sound radiation, but that does not mean that it will minimize the actual vibration. You can't tell this from a vibration measurement.
Maybe I'm incorrect here, but if you found a peak in this vibration measurement that also showed up in the speakers response and the impedance data, wouldn't this suggest to you a cabinet resonance issue. Basically what I was trying to say earlier is that, that's all I really worry about with the vibration measurements.
By the way Dr. Geddes, you aren't nice. Don't sell me speakers that make recordings I used to like sound poorly recorded. Not that it's so ruthlessly revealing that I can't listen anymore, that would probably mean something else is up, just that a few recordings I used to enjoy from time to time are now sounding painfully poorly engineered.
I'm listening to Mad Dogs and Englishmen and really enjoying it. It's a dry and somewhat lifeless recording, but oh what a performance. Soundstaging is nice on this, they seemed to do a little better than the typical beatles hard left/right bit. Joe Cocker is front and center, his piano is slightly to the right, everything is where it's supposed to be. It's pretty 2-dimentional, but that's really the recording. I need to pull out some recordings I know have more depth to their stage.
The speakers are too way too high, I want to bring them down a lot. I sat up on the back of my couch to see what a difference that made, night and day to the response. I'm basically sitting below the centerline of the vertical axis by a good 6-8" or so. At the moment it's this or stick them on the floor. I'm thinking something that's 14"-18" would be best.
Oh I take back my bright comment. Turns out I had some post processing on I didn't realize. It always makes things sound bright. My gf doesn't know how to use my stereo and she just tends to push every button on the remote to change the channel. She turned on virtual surround which was the cause of my cautious sound stage comment (I thought they sounded too good at disappearing) and a bit bright and hashy. With it off they sound much more neutral. Actually below the vertical venter axis I think they sound a little on the warm/dull side of things, which is why I really think they need to be lowered. Maybe I would prefer the 1.47uf cap too, who knows, I'll give it a shot later and see.
However, while I'm writing here and nitpicking this and that, please understand how pleased I am with the sound. I remember a very creative set of adds from I believe B&W speakers. They talked about how certain performances can cause hairs to stand up on end. A sensation I can easily relate to, and something these speakers are doing recording after recording. To me there is no better sign that a performance has delved below the surface than that, and it's something that bad sound can destroy.
Any thoughts on making a grill for the midbass driver? Maybe a formed metal grill that just presses into the space between the basket and opening? I can't imagine such a grill would impact sound much if at all, no?
By the way Dr. Geddes, you aren't nice. Don't sell me speakers that make recordings I used to like sound poorly recorded. Not that it's so ruthlessly revealing that I can't listen anymore, that would probably mean something else is up, just that a few recordings I used to enjoy from time to time are now sounding painfully poorly engineered.
I'm listening to Mad Dogs and Englishmen and really enjoying it. It's a dry and somewhat lifeless recording, but oh what a performance. Soundstaging is nice on this, they seemed to do a little better than the typical beatles hard left/right bit. Joe Cocker is front and center, his piano is slightly to the right, everything is where it's supposed to be. It's pretty 2-dimentional, but that's really the recording. I need to pull out some recordings I know have more depth to their stage.
The speakers are too way too high, I want to bring them down a lot. I sat up on the back of my couch to see what a difference that made, night and day to the response. I'm basically sitting below the centerline of the vertical axis by a good 6-8" or so. At the moment it's this or stick them on the floor. I'm thinking something that's 14"-18" would be best.
Oh I take back my bright comment. Turns out I had some post processing on I didn't realize. It always makes things sound bright. My gf doesn't know how to use my stereo and she just tends to push every button on the remote to change the channel. She turned on virtual surround which was the cause of my cautious sound stage comment (I thought they sounded too good at disappearing) and a bit bright and hashy. With it off they sound much more neutral. Actually below the vertical venter axis I think they sound a little on the warm/dull side of things, which is why I really think they need to be lowered. Maybe I would prefer the 1.47uf cap too, who knows, I'll give it a shot later and see.
However, while I'm writing here and nitpicking this and that, please understand how pleased I am with the sound. I remember a very creative set of adds from I believe B&W speakers. They talked about how certain performances can cause hairs to stand up on end. A sensation I can easily relate to, and something these speakers are doing recording after recording. To me there is no better sign that a performance has delved below the surface than that, and it's something that bad sound can destroy.
Any thoughts on making a grill for the midbass driver? Maybe a formed metal grill that just presses into the space between the basket and opening? I can't imagine such a grill would impact sound much if at all, no?
Matt
Thanks for the comments, sorry about your recordings - this has happened to everyone and its a double edged sword. Much of the older stuff is now not so good, but the newer good stuff is fantastic.
Yes, if there was a peak in the impedance curve and the same resonance ooccured in the cabinet, I would be suspicious, but its still not proof of anything. I have tracked down every glitch in the impedance and every dip in the frequency response over the years and none of them was due to the cabinet. Most are the drivers themselves, but alas, until I can afford to have custom drivers built I'm forced to "buy off of the rack".
What I have done for a grill is to carefully cut a piece of very loose weave cloth. Then use a piece of wire and press fit this all the way arround the woofer - its exactly like making a screen in silk screening. It can come out great, but it takes some practice to get started right and have the tension uniform, or it looks lopsided. Best is that you can keep trying until you get it.
Thanks for the comments, sorry about your recordings - this has happened to everyone and its a double edged sword. Much of the older stuff is now not so good, but the newer good stuff is fantastic.
Yes, if there was a peak in the impedance curve and the same resonance ooccured in the cabinet, I would be suspicious, but its still not proof of anything. I have tracked down every glitch in the impedance and every dip in the frequency response over the years and none of them was due to the cabinet. Most are the drivers themselves, but alas, until I can afford to have custom drivers built I'm forced to "buy off of the rack".
What I have done for a grill is to carefully cut a piece of very loose weave cloth. Then use a piece of wire and press fit this all the way arround the woofer - its exactly like making a screen in silk screening. It can come out great, but it takes some practice to get started right and have the tension uniform, or it looks lopsided. Best is that you can keep trying until you get it.
ok thanks. If you could take pictures of what you mean, that would be great. Also, what kind of cloth. Grill Cloth, bed sheet, etc?
Do you think there is anything to speakers needing time to break in? I mean, I know I can measure a difference in the impedance between a brand new speaker and one that has broken in, but it probably still falls within 10% or so.
You know I've chased down every source of hiss and noise I can, and every time I think I have vanished them, something comes along to reveal that they are still there. Sure enough, speakers that are 6+db's more efficient enter the picture and what do you know, some low level hum has reintroduced itself. It's not audible at the listening position, but I'm one of those weirdos who doesn't like any noise, even if I can't hear t under normal circumstances. I believe it's from the power supply in my amplifier, it's always been there, and after some tweaks I had it suppressed some, but clearly only by a few decibles. My other amp has no hum, as the power supply is dead silent, but the inferior amp circuit has shot noise that would be objectionable on these efficient speakers.
Do you think there is anything to speakers needing time to break in? I mean, I know I can measure a difference in the impedance between a brand new speaker and one that has broken in, but it probably still falls within 10% or so.
You know I've chased down every source of hiss and noise I can, and every time I think I have vanished them, something comes along to reveal that they are still there. Sure enough, speakers that are 6+db's more efficient enter the picture and what do you know, some low level hum has reintroduced itself. It's not audible at the listening position, but I'm one of those weirdos who doesn't like any noise, even if I can't hear t under normal circumstances. I believe it's from the power supply in my amplifier, it's always been there, and after some tweaks I had it suppressed some, but clearly only by a few decibles. My other amp has no hum, as the power supply is dead silent, but the inferior amp circuit has shot noise that would be objectionable on these efficient speakers.
So Grainger is Business to Business? They won't sell me the paint because I'm not a business and don't have a business ID in the state of Indiana. Now where do I buy the paint?
Thats not true here in Michigan, must be an Indiana thing. Let me see if I can have the paint sent to you. What do you want?
semi flat black. I'm having too many problems with my sprayer, so how about the spray cans. The 1600 series you recommended. 5 cans should be enough.
Dr. Geddes,
"unless you have an indoor temperature controlled and vented space - like I built"
Where does the replacement air come from?
"unless you have an indoor temperature controlled and vented space - like I built"
Where does the replacement air come from?
pjpoes said:
All this hassle with paint. FYI, Kraylon makes a very nice semi-flat black. It is very resistance to showing finger prints and such and if you want to make it a little more satin finish you can over spray it with Kraylon satin crystal clear. Last time I checked it was under $4 a can at WalMart. Not that this will help you at this point, but something to consider for the future.
noah katz said:
The room is not perfectly sealed from the rest of the home so when the exhaust fan is running it has negative pressure compared to the rest of the house and air is brought in that way. I have an air-to-air heat exchanger in my HVAC system, so when the exhaust is running, I suspect that this exchange goes slightly towards positive inward flow - normally its balanced.
It's not that I can't get spray paint, it's that those particular paints from Kraylon and Rust-o-leum are toxic, hard to use, and require a very long drying time. I have 4 cans of the Rust-o-leum equivalent, but given the weather and conditions I could spray in, it wasn't smart or safe to use.
Unless I misunderstood, the Industrial enamel that Dr. Geddes recommended is water based, no? It's also of known quality and durability for this use.
Hey Dr. Geddes have you thought about powder coating the harpers. I was looking into what it would take to start powder coating speakers, and I noted it really wasn't reasonable for something as large as the Abbey's. The Harpers could be done though, just need to get an old used oven to stick in your basement. They should fit in fine. The equipment isn't very expensive, seems like a setup could be had for under 200 that would do the job.
Unless I misunderstood, the Industrial enamel that Dr. Geddes recommended is water based, no? It's also of known quality and durability for this use.
Hey Dr. Geddes have you thought about powder coating the harpers. I was looking into what it would take to start powder coating speakers, and I noted it really wasn't reasonable for something as large as the Abbey's. The Harpers could be done though, just need to get an old used oven to stick in your basement. They should fit in fine. The equipment isn't very expensive, seems like a setup could be had for under 200 that would do the job.