Personally, I think that response looks awful good. There will be dips and peaks, nothing you can do to avoid them and I think you have done a good job of balancing them.
As for the 10 dB swing between 245 and 400, it will probably not be as bad as shown in the plot. There will be some additional lift of the low end due to the room. Reflections off of the ceiling, side walls, and rear wall will probably mess up the response a little bit more. Worst case you attack the problem with additional BSC resistance.
When I re analyzed a few of my earlier projects, I calculated responses much worse then what you are showing and the speakers still sounded very good to me and others who have visited my home. As a last resort you still have some flexibility in room placement.
Bottom line is that speakers do not behave nice and flat as shown by some other programs. The more geometric influences you add the more ragged the SPL response will become. Again, I think you have done a nice job of balancing the floor and rear wall reflections.
As for the 10 dB swing between 245 and 400, it will probably not be as bad as shown in the plot. There will be some additional lift of the low end due to the room. Reflections off of the ceiling, side walls, and rear wall will probably mess up the response a little bit more. Worst case you attack the problem with additional BSC resistance.
When I re analyzed a few of my earlier projects, I calculated responses much worse then what you are showing and the speakers still sounded very good to me and others who have visited my home. As a last resort you still have some flexibility in room placement.
Bottom line is that speakers do not behave nice and flat as shown by some other programs. The more geometric influences you add the more ragged the SPL response will become. Again, I think you have done a nice job of balancing the floor and rear wall reflections.
One other thought, right now the model is set up to calculate the reflection from the rear wall as if the front baffle is parallel to the wall. I think this would be a worst case reflection compared to a toed in enclosure. Hmmmmm ... another upgrade to add to the list. So I think your two dips are probably worst case results.
People often complain about "slow bass", and commend a system on having "fast bass."
I believe that your system will suffer from "slow bass", I'm afraid. You might ask me, what's wrong with my system?
The problem is that your design is flat at 20hz. If you want a system that is going to sound natural in a REAL ROOM, aim for a response that begins to gently droop around 40 or 60hz. Room gain will offset the droop.
If you don't believe me, Bob Brines said the exact same thing a few days ago in this thread.
Bob is right.
John
I believe that your system will suffer from "slow bass", I'm afraid. You might ask me, what's wrong with my system?
The problem is that your design is flat at 20hz. If you want a system that is going to sound natural in a REAL ROOM, aim for a response that begins to gently droop around 40 or 60hz. Room gain will offset the droop.
If you don't believe me, Bob Brines said the exact same thing a few days ago in this thread.
Bob is right.
John
John,
I believe I can revise the design to provide a sloping response. I think of the simulations as an exercise in conservation of energy. It is all there under the curve. We have the opportunity to move it about with our tuning of the enclosure and placement in its environment.
As I gain experience, the question becomes: How much? I have looked in other places for a way to estimate room gain. It may be one of those things that will only be available through placement of the speakers in the particular room.
When I get back to my home computer I'll revise the simulation and de-emphasize the bass.
Thanks
I believe I can revise the design to provide a sloping response. I think of the simulations as an exercise in conservation of energy. It is all there under the curve. We have the opportunity to move it about with our tuning of the enclosure and placement in its environment.
As I gain experience, the question becomes: How much? I have looked in other places for a way to estimate room gain. It may be one of those things that will only be available through placement of the speakers in the particular room.
When I get back to my home computer I'll revise the simulation and de-emphasize the bass.
Thanks
I have not recieved any e-mails from you recently. I check my spam filter regularly for entertainment and have not seen any speaker related e-mails. I have plenty of stock brokers with hot tips, mortgage applications, a few from some dictators wife asking for money, some dicount drug adds, a breast enlargement offer, and a bunch of no titles just to name a few.
Revisiting John's suggestion, the sim I'm working on now shows ~6 dB drop from 100 to 25Hz in the Infinite Baffle Response plot. In the "Plotted Corrected SPL Response for the System" it shows ~2 dB drop from 55 to 25 Hz. The range chosen is different because of the intrusion of room modes into the sim. I think I am understanding the point he has made. However, I am moved to question the weight to place on either of those depictions.
John, which one has more meaning?
I'll post the screen shots in a moment. Gotta take care of a honey-do.
John, which one has more meaning?
I'll post the screen shots in a moment. Gotta take care of a honey-do.
The way I went about inducing a slope in the response was to shorten the line length, along with lengthening the port.
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I still have the floor bounce and rear wall reflections in the simulations. I know from the sim's I have run that I retain the option to position the completed speaker within my room. I may experiment with wall treatments as well.
![IMGDEAD]](/community/proxy.php?image=http%3A%2F%2F%5BIMGDEAD%5Dhttps%3A%2F%2Fi16.photobucket.com%2Falbums%2Fb31%2Fedlafon%2FSPLCorSys18.jpg%5B%2FIMGDEAD%5D&hash=3679e36ae62a2b48051b2a94e0af9eb3)
I still have the floor bounce and rear wall reflections in the simulations. I know from the sim's I have run that I retain the option to position the completed speaker within my room. I may experiment with wall treatments as well.
L = 33.5 in
Zdriver = 10.25
Zport =31.0
So = 16 x 7.5
Sl= 16 x 7.5
Dens = 0.25
r port = 1.0
Lport = 5.0
Post #296 includes the driver parameters.
There will be a space under the enclosure to get the tweeter up to a suitable level, ~29" above the floor. Although this is a few inches lower than I want, the comprimise is to get all the cuts from one sheet of mdf. I may angle the face back slightly with spikes to overcome the lack of height.
I expect the low end will be limited by an x-max of 6mm for the RS180.
This will be a "mule" to test the design. I've had the parts too long...time to build something.
Zdriver = 10.25
Zport =31.0
So = 16 x 7.5
Sl= 16 x 7.5
Dens = 0.25
r port = 1.0
Lport = 5.0
Post #296 includes the driver parameters.
There will be a space under the enclosure to get the tweeter up to a suitable level, ~29" above the floor. Although this is a few inches lower than I want, the comprimise is to get all the cuts from one sheet of mdf. I may angle the face back slightly with spikes to overcome the lack of height.
I expect the low end will be limited by an x-max of 6mm for the RS180.
This will be a "mule" to test the design. I've had the parts too long...time to build something.
Hi John,
I wish I were cutting now...I've got a couple of other projects, honey do's included, that I must complete first. This is definitely in the cue. I have a piece of material called "LVL" that is used for headers in residential construction. It is multi-ply, strand oriented and over 1 1/2" thick. I will use that material for the baffles.
I wish I were cutting now...I've got a couple of other projects, honey do's included, that I must complete first. This is definitely in the cue. I have a piece of material called "LVL" that is used for headers in residential construction. It is multi-ply, strand oriented and over 1 1/2" thick. I will use that material for the baffles.
so, finally downloaded the new sheets... one thing I soon learned: don't go to the results section of the bafle step calc when using a Pentium III 650MHz 
but one small question: is there a difference in the calculation? I compared the results from the driver offset model for a Tangband W6-1108SA in a 1.65m long TL (S0=2.5Sd SL=0.8Sd), and I see some differences in the results, not large but noticible. I double checked my input, both are identical.
another thing I noticed: when setting the parameters for 2 drivers in paralel (so: Sd double, Vas double, Re halved) the response changes quite a bit
I''ll attach the SPL curves
but one small question: is there a difference in the calculation? I compared the results from the driver offset model for a Tangband W6-1108SA in a 1.65m long TL (S0=2.5Sd SL=0.8Sd), and I see some differences in the results, not large but noticible. I double checked my input, both are identical.
another thing I noticed: when setting the parameters for 2 drivers in paralel (so: Sd double, Vas double, Re halved) the response changes quite a bit
I''ll attach the SPL curves
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