well ok to be fair Dr Geddes, I had to do something. I mean, they needed to be sealed before too long. I didn't spray them literally outside. I sprayed them inside an insulated garage with a garage heater. However, the garage heater is undersized and could only get the garage up to around 50-60 degrees. I did apply the BIN primer inside, but in an extra bedroom with the window open.
I really don't have any finish problems right now, things seem to be ok. The only finish problem is caused by the finish I chose, and it may just need more time to set. They are all inside now.
Keep in mind that while the ambient temperature was 55 degrees or so, I had drying lamps on the boxes even while spraying. I bet the temp they were being sprayed in was a lot warmer.
The problem with that initial panel was that the temperature had dropped to below zero again the same night I sprayed, and I had turned the lamps off when I went to bed. I should have brought the panel inside. The rest of the panels are fine, and I've had no peeling off issues like I did on the one. None the less, they will be refinished with the better paint when weather permits.
I really don't have any finish problems right now, things seem to be ok. The only finish problem is caused by the finish I chose, and it may just need more time to set. They are all inside now.
Keep in mind that while the ambient temperature was 55 degrees or so, I had drying lamps on the boxes even while spraying. I bet the temp they were being sprayed in was a lot warmer.
The problem with that initial panel was that the temperature had dropped to below zero again the same night I sprayed, and I had turned the lamps off when I went to bed. I should have brought the panel inside. The rest of the panels are fine, and I've had no peeling off issues like I did on the one. None the less, they will be refinished with the better paint when weather permits.
planet10 said:
I guess that I would not agree with this. I have not noted, nor do I know of any valid data to say that any material "sounds" any better than any other. I've use a multitude of different materials from carbon fiber and fiberglass to cast acrylic (like countertops) to MDF. Nothing was ever apparent as a difference in sound in any of these materials. (Although finishing them is vastly different). Thats why I use MDF - keeps the cost down and the performance up, thats what a good engineer does.
pjpoes said:
I'm rethinking this. It may be best to just let the cabinets set for a week and "settle-in" before spraying them. Turns out that I do this without thinking because I can never do anything in a short time period.
The problem with the garage is the temperature cycling. Unless you are willing to dump big bucks into heating it its going to cycle and this is going to be a problem. I can sympathize with you as I used to heat my garage in the winter and spray out there so I know the problems. Then once in the summer, I sprayed some speakers in the morning, they looked great. Then I forgot that the sun moves (DA!!) and by noon they were sitting directly in the hot sun (they were black!) and the part in the sun had literally blistered the paint off. Ruined the whole paint job.
Basically unless you have an indoor temperature controlled and vented space - like I built - you are never going to get a great finish, only an acceptable one. I've been trying for "great" for years and can now do it, but it ain't easy.
here is one assembled, minus the foam plug. I thought I had the foam in one of the pictures I took, guess not. Hopefully the other two will be done tomorrow.
Dr. Geddes had mentioned that I would be using some different parts in mine. I actually used all the parts he supplied except one. The only place I ever thought I really heard a difference from cap parts was in the series caps and resistors in the tweeter network. I happened to have some ClarityCap SA caps laying around, so I installed those in place of the Solen supplied series cap. That is the only thing I changed. I may change to mills wirewound in the series resistors later on, or MOX, we shall see. Let's see how it sounds as is, no. Another possible upgrade (I probably won't end up bothering here), is the inductor in the lowpass. The steelcore is fine, it has very low resistance. However those Jantzen toroid core inductors have really low dcr, and seem like a nice potential option. Another would be to wind my own, which I've been messing around with.
Matt
If you do change inductors its important to match the dcr as the response can change if this value changes. You probably have a .47 uF cap left over?
If you do change inductors its important to match the dcr as the response can change if this value changes. You probably have a .47 uF cap left over?
yes I do. You said that was optional to tailor the response, no? Would you mind describing the effect again, with it you have a more rolled off response, without it, less? I think I missed your initial discussion on this topic.
Does the DCR of the woofer series inductor matter? That's the only one I would change. Quality of the LCR inductors doesn't impact sound at all in my opinion. In fact, it probably wont int he woofer as that is a decent inductor, but they handle a lot more power, and waste less energy as heat. I believe DCR would change from .3 to .03.
I took distortion measurements through the inductor on my oscilloscope once. Well, I subtracted the output from the input signal after going through various inductors to see which ones least severely changed the response, and in what ways. I did this at various frequencies as well. I kept reading about inductor distortion and wondered about testing this and core saturation. While I don't know about an impact on sound (I couldn't hear an impact on sound, as these inductors saturated at a level way beyond comfortable listening levels or driver capabilities), there was clear differences between the different inductors. It's why I became interested in winding my own, to experiment with this and see if I can't make my own inductors that perform well and don't cost me an arm and a leg.
Does the DCR of the woofer series inductor matter? That's the only one I would change. Quality of the LCR inductors doesn't impact sound at all in my opinion. In fact, it probably wont int he woofer as that is a decent inductor, but they handle a lot more power, and waste less energy as heat. I believe DCR would change from .3 to .03.
I took distortion measurements through the inductor on my oscilloscope once. Well, I subtracted the output from the input signal after going through various inductors to see which ones least severely changed the response, and in what ways. I did this at various frequencies as well. I kept reading about inductor distortion and wondered about testing this and core saturation. While I don't know about an impact on sound (I couldn't hear an impact on sound, as these inductors saturated at a level way beyond comfortable listening levels or driver capabilities), there was clear differences between the different inductors. It's why I became interested in winding my own, to experiment with this and see if I can't make my own inductors that perform well and don't cost me an arm and a leg.
gedlee said:
Earl - perhaps a cue for a new thread - I'd be very interested to hear how you achieved this, assuming you did it without spending tens of thousands.
Waiting for a warm, dry, windless weekend for spraying in the UK is usually a somewhat futile exercise.
pjpoes said:
john k... said:
Yes, but "notch" may be a misnomer as they are mostly all low Q dips of only a few dB. One is actually below the HP filter point and hence is really part of the HP filter function. One is set at the drivers resonance since there is always more output here than needed, and the final one brings down a resonance that occurs across the mouth of the waveguide. This last one is very shallow.
By the way, I took impedance and electrical phase measurements yesterday to make sure the crossovers were right. Given that this is a waveguide speaker, I was amazed at the smoothness of the impedance plot. Also, I originally took measurements with no back on just to make sure things were ok, then with the back on but no dampening material. I had a few impedance glitches in the midrange area of the woofer that went away after inserting the dampening materials.
Phase response is excellent, Kudo's Dr. Geddes. Phase response seemed to remain within a +/- 30-40 degree window or so.
Phase response is excellent, Kudo's Dr. Geddes. Phase response seemed to remain within a +/- 30-40 degree window or so.
Any recommendation on speaker stands and speaker stand height. What I have now seems all wrong. They are 24" high steel stands that are too small and too tall. I was thinking maybe an 18" stand with a broader base.
I'm thinking of maybe using one of those modern accent tables like they sell at home stores for a stand. Would look nice, and maybe be the right height and all. The other option is to build one, but I'm not in the mood for another project.
I'm thinking of maybe using one of those modern accent tables like they sell at home stores for a stand. Would look nice, and maybe be the right height and all. The other option is to build one, but I'm not in the mood for another project.
sploo said:
First I sealed off a small space of about 12 x 10 along an outside wall. Remember that it gets very cold here so venting can't just be done with an open window. Then I built a box in the corner and installed an inline fan as used in HVAC to increase air flow in a duct. The box was just a piece of ply across one corner of the space. In this board there is a square hole and I place a furnace filter in this hole. This clogged up very fast and now I use some scrap foam as a prefilter, which has to be cleaned often - just vac out the dust.
I ran the outlet to the outside with a typical vent damper installed to prevent back flow when the fan is off.
This proved to be insufficient as far as taking out dust and overspray. SO I got a room fan, you know about 19" diameter large blades and I put this in the hole and the filters in front of it. With this in place the box is now pressurized and the exhaust fan works much better. This system removes dust and overspray very well.
This room acts as a spray booth and a dust trap as I do all the dusty work in there. This became necessary when I was getting dust everywhere in my home and it was out of control. This room, with its negative pressure keeps the dust way down in the rest of the house, but this room gets very dusty.
I need to use this space in two manners. First, all the dusty work must be done on the table saw router etc. Then the room has to be cleaned very well and wet down. This wetting keeps the remaining dsut from getting airborn. In this condition it is a spray booth and vents the fumes outside. Its also a smoking room when guests who smoke come over as my wife won't allow smoking anywhere else.
In my room I use drop plastic curtains - strips of heavy plastic hung vertically. This allows easy and fast entrance and exit with minimum airflow.
This has proven to work quite well, but the filters clog fast and the room needs to be thoroughly clean often or you track dust from your feet into the rest of the house.
pjpoes said:
The best looking stands that I have seen are the ones that Markus showed in his thread on the Nathans. Just put the center of the speaker at about ear level.
Do you think the Bose 901 stands could support these? Also, I believe those are too tall. I would have to check.
This is what I was considering
Only problem is it's really too big. It's 16" square and 20 inches high.
This is what I was considering
Only problem is it's really too big. It's 16" square and 20 inches high.
An externally hosted image should be here but it was not working when we last tested it.
But I wouldn't put a heavier speaker than the Nathans on those. How much more is the Abbey?
Best, Markus
Matt
Look good, can't speak to anything else.
Markus
You mean "wouldn't" right? The Abbey weighs a lot more.
Look good, can't speak to anything else.
Markus
You mean "wouldn't" right? The Abbey weighs a lot more.
I haven't weighed the speakers yet, but I would guess around 60lbs each? Does that sound right Dr. Geddes? I'm basing it soley on the ease/difficulty I had lifting them 24" off the ground. It was something that involved lifting with the knees, not the back, but wasn't so heavy as to be barely liftable. I have a 90lb SET tube amplifier I took back with me from NY, and that was something that I would not have been able to lift up 24" as easily.
gedlee said:
Many thanks for the info. Unfortunately, 10x12 would be very optimistic for me (my garage is packed with tools). Though I may one day be able to add a (much smaller) shed in my garden for spraying.
Just some notes:
1) For most of this kind of application, people talk about using fans with explosion-proof motors, because of the combustibility of many paints being sprayed. Just wondering on your thoughts/experience of this (you're still here, so you obviously haven't blown yourself up!)
2) What personal protection (respirator) do you use for spraying paints?
3) If you are working with (cutting) MDF I'd strongly recommend an MDF rated (dust and vapours) mask, as it's pretty nasty stuff. This (http://spikyfish.com/DustExtraction/) is how I extract wood dust, and also shows the lack of space I have!
The inline fan is explosion proof, but the room fan is not.
I use a 3M respirator which is good but not great at MDF and paint fumes.
I use a 3M respirator which is good but not great at MDF and paint fumes.