Ok I want to start making my boxes. The Bang is 46 liters. Any calculator I run the 55-1170 specs through comes up with 69 Liters for ported, based on the current specs of the 1170. As I mentioned in a previous post the specs on the 1170 may have change since the Bang was designed. Or does it not matter and you can arbitrarily choose a box size? How big should I make the box? Then we'll go from there So confused!!!😕😕😕
Tony
Hey Tony, I understand your frustration and why you are sensitive at this point. I'm on your side here. It just seems to me that the wise ones are spending a lot of time on a project that could be done quickly considering the starting point ie: inexpensive drivers. I feel for you with the bombardment, that's all. In any event I simply lashed out as it's obvious some of this is beyond what you seem to have intended with your first post.
No I won't close this, I am posting as a member, I'm only a mod when I have to be.
Anyway perhaps I should steer clear. I wish you the best with this project and hope you continue to post about it as you start hearing some results.
No I won't close this, I am posting as a member, I'm only a mod when I have to be.
Anyway perhaps I should steer clear. I wish you the best with this project and hope you continue to post about it as you start hearing some results.
Mate, I've been getting fed up with it too. But keep focussed on the game is what you do.
I'm no great shakes on reflex. But it's always a moveable feast. There are many different box tunings which correspond to different slopes and tuning frequency. QB3, QB4, stuff like that...😕
Consider this Qts 0.52, Vas 36L, 6" W170S paper driver. 20L, 30L or 50L tunings calculated at Visaton. Take your pick. The tube gets longer as the box gets smaller is how I look at it. Eventually the tube is bigger than the box and it becomes impossible.
W 170 S - 8 Ohm
If Dan Wiggins likes 46L and a 4" dia, 8" long tube, that will do for me. I do think you could align the drivers vertically and make the box taller and narrower if your wife has strong views. They are offset near the edges already, and I doubt it'll make a huge difference. Diffraction effects are always a bit more here and a bit less there, so it probably mostly averages out. You might lose a bit of level in the midrange on a narrower baffle, that's all.
BTW, this hasn't been a waste of time for me at all. I have firmed up some ideas here on my next project. Thankyou. 😎
I'm no great shakes on reflex. But it's always a moveable feast. There are many different box tunings which correspond to different slopes and tuning frequency. QB3, QB4, stuff like that...😕
Consider this Qts 0.52, Vas 36L, 6" W170S paper driver. 20L, 30L or 50L tunings calculated at Visaton. Take your pick. The tube gets longer as the box gets smaller is how I look at it. Eventually the tube is bigger than the box and it becomes impossible.
W 170 S - 8 Ohm
If Dan Wiggins likes 46L and a 4" dia, 8" long tube, that will do for me. I do think you could align the drivers vertically and make the box taller and narrower if your wife has strong views. They are offset near the edges already, and I doubt it'll make a huge difference. Diffraction effects are always a bit more here and a bit less there, so it probably mostly averages out. You might lose a bit of level in the midrange on a narrower baffle, that's all.
BTW, this hasn't been a waste of time for me at all. I have firmed up some ideas here on my next project. Thankyou. 😎
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Sorry about that Tony, The HDS is a very well known Peerless (pretty expensive) soft dome driver now branded as a Scan Speak. The TBFC/G is a Seas aluminum dome, not quite so pricey, but not what you are looking for yet. A Google search is usually all that is necessary.
Best By has plenty of inexpensive speakers sold as just a pair. Cheaper Polk or Warfdale Diamond series are well worth the cost. We can build better, but not for less.
Build the boxes. Stick in the woofers and play with different port tube lengths. If you read D'Apolitto's book, he shows you how to measure the impedance change between sealed and ported to calculate the real box tuning so you can see if it correlates to the model. It won't by the way. Speaker building is about very large tolerances. 20% is not bad. Use the VIfa's. Good value and not too hard to use. Just don't cross them over too low. I tried them at 1800 once to prove how bad it was. 2500 second order they like much better.
PS: We all went over the edge years ago. This is not a hobby for the sane. It is a lot more fun than most hobbies that are. 😀
Let's see if this helps.
Sealed box = smaller and less bass
Ported box = larger and lower bass
Each box is open to large variations in design parameters depending on how you want the response to turn out.
Since you mention that you're not hearing the low frequencies as well any more, I would think that what you want is a speaker that is a little heavier in the bass department. The best way to do this might be with a subwoofer whose volume you can adjust independently but you can also set up a ported speaker to give you an extra boost in the bass too. You do this by building a larger box and/or tuning the port to be just a little higher than normal.
In the graph below are the low frequency responses of 2 of your MCM's in different size boxes and port tunings (or what are referred to as alignments). The purple line has the flattest tuning before it starts falling off at about 30Hz. That's in 100L (1cft = 28.317L) with the port tuned to 32Hz.
The blue line shows the bass boost that I was talking about and that I think might be right for your situation. You loose a little bass extension but since most music doesn't have much content below 40Hz anyways, I wouldn't worry about it. This is in 100L still but the port is a different length and tuned to 40Hz. And this boost is adjustable.
I just added the 3rd curve to show you what happens in a smaller box, this time 56L and the port still tuned to 32Hz. Interestingly, this response is starting to look more like the response you get with a sealed enclosure.
So given this, you may want to decide what shape response is going to work best for you and also exactly what size box you and your wife want to live with and then we can tell you what size port to use.
Hope that helps but if anything isn't clear, just ask.
Sealed box = smaller and less bass
Ported box = larger and lower bass
Each box is open to large variations in design parameters depending on how you want the response to turn out.
Since you mention that you're not hearing the low frequencies as well any more, I would think that what you want is a speaker that is a little heavier in the bass department. The best way to do this might be with a subwoofer whose volume you can adjust independently but you can also set up a ported speaker to give you an extra boost in the bass too. You do this by building a larger box and/or tuning the port to be just a little higher than normal.
In the graph below are the low frequency responses of 2 of your MCM's in different size boxes and port tunings (or what are referred to as alignments). The purple line has the flattest tuning before it starts falling off at about 30Hz. That's in 100L (1cft = 28.317L) with the port tuned to 32Hz.
The blue line shows the bass boost that I was talking about and that I think might be right for your situation. You loose a little bass extension but since most music doesn't have much content below 40Hz anyways, I wouldn't worry about it. This is in 100L still but the port is a different length and tuned to 40Hz. And this boost is adjustable.
I just added the 3rd curve to show you what happens in a smaller box, this time 56L and the port still tuned to 32Hz. Interestingly, this response is starting to look more like the response you get with a sealed enclosure.
So given this, you may want to decide what shape response is going to work best for you and also exactly what size box you and your wife want to live with and then we can tell you what size port to use.
Hope that helps but if anything isn't clear, just ask.
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No need to say sorry. I'm just trying to learn and grasp all I can.
Thanks for the info.
Tony
Thank you. That was very helpful. There is no way I can go for 100L. I can probably aim for 60L at best. To me it sounds like I can play around here and install a port and at some point remove and block the port hole to make it sealed just to hear the difference. Is that in fact correct?
Thanks
Tony
Steve. Is that W 170 S something I could (or want to) upgrade to at a later date using the same box?
Two more (probably dumb) questions. Does the crossover change if its ported or sealed? What do you suggest for a target baffle width?
We are getting a snow storm this weekend. Good time to start building these.
Thanks for all your help
Tony
Ok, I wasn't sure how big you could go. 60L looks like it will work just about as well. The internal volume is the net volume by the way, ie. the amount of volume you have left over after you subtract out the space that the drivers, the port, the xo's and any internal bracing also take up.
So this time in the graph below, I've used 55L as your net volume starting with about a 60L cabinet. It's a rough guestimate. Included is the 100L size just for comparison purposes. Notice that all I'm doing with the different tunings is changing the port length - a longer port gives you a lower tuning. A shorter port gives you a higher tuning but also makes it a bit louder. I've added the sealed response as well - just stuff the port with something like foam or a pair of socks and that will do the trick. My thoughts are that you're going to prefer the ported response.
Now, one thing to note is that these are only simulations based on the manufacturer's specs and these might vary somewhat from what you have in your hands. As such, it would be best for you to experiment with the different port lengths and see which one your ears prefer.
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Thank you so much. The only thing I know how to test on a raw driver is the Fs. Not sure if you read in one of my previous post but the ones I have on hand the Fs is closer to 55Hz as opposed to the MCM spec of 40Hz. How much would that change things or does it not matter much?
Tony
Tony,
A higher Fs will have no effect on Fb (box tuning) but will reduce output when Fb is lower than Fs.
You can determine actual Fb by looking at a white dot painted on the cone while sweeping sine wave tones, the cone movement will be at minima at Fb.
If you do not have a sweepable tone generator, you can find fixed tone generators available on line.
The upper response of the speaker is not affected by tuning (other than port resonance) or sealing so in general does not affect the crossover.
Thanks. Thats interesting and worth knowing. I do have a sweepable bench signal generator. I'm learning I think. Lets see, this must mean that if I change the port length, I can watch the white dot while sweeping and see the effect it had on Fb. If not then I'm a complete basket case and will never be able to figure out all this speaker stuff.
Tony
Drivers also usually need a little time period to 'break in' which means that initial measurements of the drivers may change a little, maybe closer to specs, maybe not. This is also why I suggested the best thing to do would be try out some different length ports and see what sounds best to your ears. Some 2.5" PVC pipe from Home Depot will work well. Give the drivers a little time to break in first - maybe a day or 2 working some decent SPL's.
Also, can't remember if this has already been suggested but you might want to make your front baffle removable as apposed to glueing it on permanently. That will help with the port experimentation but will also mean that if you don't like the results with these drivers, you can re-use the cabinets by just making a new baffle for new drivers.
You can also usually get a little extra box volume out of a design by increasing the depth but leaving the height and width the same without making it look that much bigger.
Also, the internal cutout for the MCM is 5.83". Let's call it 6", add 1/2" on each side to help it breath a little and then add say 3/4" thickness for each side of the cabinet and you have an 8.5" wide speaker. You could go as thin as 8" or as wide as 10". That's sort of up to you but you should let Steve know because the baffle width affects the baffle step loss which affects the value of the inductor in the low pass xo.
Also, can't remember if this has already been suggested but you might want to make your front baffle removable as apposed to glueing it on permanently. That will help with the port experimentation but will also mean that if you don't like the results with these drivers, you can re-use the cabinets by just making a new baffle for new drivers.
You can also usually get a little extra box volume out of a design by increasing the depth but leaving the height and width the same without making it look that much bigger.
Also, the internal cutout for the MCM is 5.83". Let's call it 6", add 1/2" on each side to help it breath a little and then add say 3/4" thickness for each side of the cabinet and you have an 8.5" wide speaker. You could go as thin as 8" or as wide as 10". That's sort of up to you but you should let Steve know because the baffle width affects the baffle step loss which affects the value of the inductor in the low pass xo.
Did you use a load resistor(s), gen. and volt meter? You'll want to lean that, it will come in handy later on when you want to check box tuning.
Just remember volt meter always goes on speaker leads.
"Thank you so much. The only thing I know how to test on a raw driver is the Fs"
Just remember volt meter always goes on speaker leads.
"Thank you so much. The only thing I know how to test on a raw driver is the Fs"
Tony, I was just re-reading some of your thread and I noticed that Steve suggested that the MCM's were only suitable for a closed box. He may know more than I do on this subject but I tend to be of the 'give a try and see what you think' school of thought.
If you are forced to use a closed box, I would think that it won't provide enough bass to satisfy your hearing. Again, you'll want to try it and see.
FWIW, the Vifa tweeter that you have has very acceptable distortion measurements and has been used with success in a well known design, The Stentorians - Speaker Design Works. Since you already have one of them, I can't really see any reason not to buy another one and use those. It looks like you could also use that high pass xo as a starting point for them but you'll have to pad them down some more with more resistance.
If you are forced to use a closed box, I would think that it won't provide enough bass to satisfy your hearing. Again, you'll want to try it and see.
FWIW, the Vifa tweeter that you have has very acceptable distortion measurements and has been used with success in a well known design, The Stentorians - Speaker Design Works. Since you already have one of them, I can't really see any reason not to buy another one and use those. It looks like you could also use that high pass xo as a starting point for them but you'll have to pad them down some more with more resistance.
Tony,Lets see, this must mean that if I change the port length, I can watch the white dot while sweeping and see the effect it had on Fb. If not then I'm a complete basket case and will never be able to figure out all this speaker stuff.
You will notice longer ports lower Fb, the point where cone excursion is at minima.
Lower Fb will result in less output from the port, a drooping LF response.
If the Fb is too low, there will hardly be a difference between ported and sealed.
Too high, and the response will "boom" in a narrow range.
I'll make the baffle removable (Steve suggested it as well). I thinking about going around 34" H, 13" or so deep and some where around 9-10" wide for the box and thats probably going to end up more like 55L internal volume not counting the space the drivers take up or the battens for making the front removable.
I was thinking of having a 4" X 8" cutout in the rear panel, mounting the crossover and binding posts to a 5" X 9" 1/8" thick anodized aluminum plate and using that plate to cover the opening thus giving me easy access to the crossover. Any reason why thats a bad idea?
Tony
Yeah I think Steve's preference is for sealed for these drivers but he mentioned that he'll go along with ported. The Adire Audio's Bang used the MCM drivers and it was ported. This is all just a learning project. I'm sure in a month or so I'll be ripping the baffle off these and changing drivers or starting from scratch on something different.
Thanks again for your help.
Well I used a resistor in series with the driver and an oscilloscope on the speaker leads and swept my signal generator till I saw a peak reading on the scope.. I'm sure my method is not entirely right and I did not have the speaker mounted to anything. Just sitting face up on the bench.
Yes, there is a good reason why that's a bad idea.
Aluminum will change the inductor values quite a bit, as you can see here:
http://www.troelsgravesen.dk/coils.htm
Plastic, wood or fiberglass would be a better choice, though some care should be given to the heat that resistors can generate, I have seen scorched wood and fiberglass and melted plastic in a number of designs.
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