salas,
I know who Tom Danley is and have read some of his posts in the past. I agree with some of the things he states and disagree with others.
But returning to your post, I still disagree with your entire post. It would appear you have not used the driver or heard it in a system like I have designed, actually built, and was listening to less than an hour ago. Yet you make recommendations for altering the driver based on speculation. I am not going to waste any more of my time replying to you, we can agree to disagree.
I know who Tom Danley is and have read some of his posts in the past. I agree with some of the things he states and disagree with others.
But returning to your post, I still disagree with your entire post. It would appear you have not used the driver or heard it in a system like I have designed, actually built, and was listening to less than an hour ago. Yet you make recommendations for altering the driver based on speculation. I am not going to waste any more of my time replying to you, we can agree to disagree.
Martin, just a couple of questions....
After exploring the OB speaker type and being stupid enough to expose my kids to them, my eldest daughter has asked for a room friendly OB speaker pair for her new apartment. My JELabs style OBs simply take up too much real estate on the floor.
I did read through your quite excellent article. I enjoyed it very much.
One question regarding the baffle enters my mind however. Is the baffle canted slightly rearward or is it purely vertical? If it is canted rearward slightly, the CG of the baffle/loudspeaker assembly would be more stable than if vertical. Your thoughts?
This is of course more of a paractical consideration rather than one designed to create a time coherent design via a front that is sloped vs one that is not.
Also would "wings" such as those used in the Visaton No Box design be suitable for use? Thanks for your excellent article and continued design work.
With the Cdn dollar at par nowadays, it would make sense to purchase the drivers soon (before our dollar plumets, as history has typically illustrated)
stew
After exploring the OB speaker type and being stupid enough to expose my kids to them, my eldest daughter has asked for a room friendly OB speaker pair for her new apartment. My JELabs style OBs simply take up too much real estate on the floor.
I did read through your quite excellent article. I enjoyed it very much.
One question regarding the baffle enters my mind however. Is the baffle canted slightly rearward or is it purely vertical? If it is canted rearward slightly, the CG of the baffle/loudspeaker assembly would be more stable than if vertical. Your thoughts?
This is of course more of a paractical consideration rather than one designed to create a time coherent design via a front that is sloped vs one that is not.
Also would "wings" such as those used in the Visaton No Box design be suitable for use? Thanks for your excellent article and continued design work.
With the Cdn dollar at par nowadays, it would make sense to purchase the drivers soon (before our dollar plumets, as history has typically illustrated)
stew
Hi,
Well some net surfing produced not a single measured frequency
response of the FE103 - which is not a good thing because the
Fostex curves cannot be trusted :
See : http://www.troelsgravesen.dk/FE126E.htm
Some measured data on the FE103 would be useful .....
/sreten.
Well some net surfing produced not a single measured frequency
response of the FE103 - which is not a good thing because the
Fostex curves cannot be trusted :
See : http://www.troelsgravesen.dk/FE126E.htm
Some measured data on the FE103 would be useful .....
/sreten.
I should be getting the parts this week and will be putting it together this weekend. I'll post my impressions.
One thing that appeals to me about this design is its inherent simplicity and ease of construction. Once the drivers are broken in and I'm more accustomed to their sound, I'll order up a pair of phase plugs from Planet-10, that should (in theory) help with the HF dispersion. Again, I'll be sure to post my impressions. If I like the sound, more mods will follow (enable, mamboni, etc...).
I have a question about the baffle, though. Would it be a good idea to slant the outside edge of the baffle (think apogee speakers)? I would think this should help break up resonant modes. Opinions?
I'd also like to thank Martin for taking the time and for the effort to put this project out for us to try. I'd love to see a design using two Alpha 15A's and a B200 per side, I bet that'd rock! But for now, the anticipation is killing me, it's like Christmas when I was a kid!
sreten...and MJK too
er... sreten, I was asking MJK. However your thoughts and comments are appreciated.
Your thoughts are in itallics? The wings I am refering to are more so baffle "legs" or whatever one might call the side panels of something like the Visaton NoBox design.
My experience with the JELabs/Stereo Sound OBs indicate that a full width "top shelf" and a side wing or "upright" brace between the two also helps bass, although I have no measurements to prove to what extent.
38" X 20" baffles appear friendly enough, as long as the woofer magnetic fields don't kill a tv from 3' or 4' away.
er... sreten, I was asking MJK. However your thoughts and comments are appreciated.
Your thoughts are in itallics? The wings I am refering to are more so baffle "legs" or whatever one might call the side panels of something like the Visaton NoBox design.
My experience with the JELabs/Stereo Sound OBs indicate that a full width "top shelf" and a side wing or "upright" brace between the two also helps bass, although I have no measurements to prove to what extent.
38" X 20" baffles appear friendly enough, as long as the woofer magnetic fields don't kill a tv from 3' or 4' away.
Re: Martin, just a couple of questions....
Hi Stew,
Thanks for the positive feedback. It was a fun article to write, putting the curves together and feeling the lightbulb above my head flicker as I began to understand the relationships that produced the plotted responses has really helped me see OB design trade-offs more clearly. While there are many other ways to make an OB system work well, I liked using the acoustic properties of the baffle and the relationships between the driver SPL levels to produce a flat response.
Tilting the baffle back or adding some small side and top wings, like the Visaton design, seem like decent ideas but I have no idea how significant a change in the SPL response they will produce. Probably not much if I had to guess. I had envisioned a baffle made of two layers of 3/4 inch think plywood with a damping material sandwiched for a total thickness between 1.5 and 1.75 inches. Adding a flat piece of plywood to the bottom protruding in the front and back to form a foot and I was done with the design. Again, simple and cheap.
Hope that helps,
Nanook said:
Hi Stew,
Thanks for the positive feedback. It was a fun article to write, putting the curves together and feeling the lightbulb above my head flicker as I began to understand the relationships that produced the plotted responses has really helped me see OB design trade-offs more clearly. While there are many other ways to make an OB system work well, I liked using the acoustic properties of the baffle and the relationships between the driver SPL levels to produce a flat response.
Tilting the baffle back or adding some small side and top wings, like the Visaton design, seem like decent ideas but I have no idea how significant a change in the SPL response they will produce. Probably not much if I had to guess. I had envisioned a baffle made of two layers of 3/4 inch think plywood with a damping material sandwiched for a total thickness between 1.5 and 1.75 inches. Adding a flat piece of plywood to the bottom protruding in the front and back to form a foot and I was done with the design. Again, simple and cheap.
Hope that helps,
BHD said:
I think that you are asking about making the baffle more of a trapazoid. I don't know how this would change the response. You could look at the rectangle vs the trapazoid shape in the EDGE or my OB worksheets and see if it makes a significant difference.
I am looking at a another dual Alpha 15A OB design but I don't think it will be for the B200. I have a few other drivers in mind and I just cannot keep accumulating more full range drivers. So I think for now the B200 is not under considered.
I am looking forward to hearing your impressions.
Re: sreten...and MJK too
Hi,
Yes they are in italics.
As the "wings" cannot be modelled in the "Edge" some approximations
would have to be made and the reduced baffle size / width would
affect the modeled FE103 baffle response.
If you mean adding them to the 38" x 20" baffle :
This would cause a lift in the bass response talking it above "target".
But other than approximating it by increasing the apparent size
of the baffle I do not know how to model it. In this case the
the FE103 modeled baffle response would be valid.
I guess the best way if you wanted the smallest baffle possible
would be to angle it back and drop driver and overall height and
add angled side wings - given the layout for bass a top wing will
make little difference as I see it.
To do this ideally you need to be able to meaasure, and measure
a baffle with / without the wings to ascertain the correction factor,
which as I see it would be a increase in effective width for bass.
Still ....
Measurements of the FE103 would be extremely useful ....
I suspect it will need a filter for upper midrange control and would
work extremely well with an Apex jr $1 special or the the neo
PE mini tweeter ($5) used as a supertweeter :
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=275-025
The project appears to be simple because of the assumptions made
about the FE103. In a real build these only apply below the first
breakup mode of the FE103 - appears to be around 2kHz judging
by the impedance graph. Above this point not much is guaranteed.
/sreten.
Nanook said:
Hi,
Yes they are in italics.
As the "wings" cannot be modelled in the "Edge" some approximations
would have to be made and the reduced baffle size / width would
affect the modeled FE103 baffle response.
If you mean adding them to the 38" x 20" baffle :
This would cause a lift in the bass response talking it above "target".
But other than approximating it by increasing the apparent size
of the baffle I do not know how to model it. In this case the
the FE103 modeled baffle response would be valid.
I guess the best way if you wanted the smallest baffle possible
would be to angle it back and drop driver and overall height and
add angled side wings - given the layout for bass a top wing will
make little difference as I see it.
To do this ideally you need to be able to meaasure, and measure
a baffle with / without the wings to ascertain the correction factor,
which as I see it would be a increase in effective width for bass.
Still ....
Measurements of the FE103 would be extremely useful ....
I suspect it will need a filter for upper midrange control and would
work extremely well with an Apex jr $1 special or the the neo
PE mini tweeter ($5) used as a supertweeter :
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=275-025
The project appears to be simple because of the assumptions made
about the FE103. In a real build these only apply below the first
breakup mode of the FE103 - appears to be around 2kHz judging
by the impedance graph. Above this point not much is guaranteed.
/sreten.Sorry for the delay but I did not want to post without looking to see exactly what I finally arrived at for a crossover. I am currently using a 1 uF Solen cap in series with the Fostex FT17H super tweeter. I tried a few other values between 1 and 3 uF and liked the 1 uF best. The super tweeter adds just a bit more sparkle, nothing really significant just that last little bit.
At the time I only had two amps so running a the three way through the dBx crossover was not possible. I have since picked up a third matching amp but have not worked it into the system yet. Hence, a passive solution.
Hope that helps,
Correct. It's not going to be extreme, I'll probably end up making the top 19" and the bottom 21".
I wish Eminence made a 16 ohm version of the Alpha 15A, a "woofer - full range - woofer" tall, relatively slim version with a visaton B200 or Supravox 215 Signature Bicone could be really cool.
Oooohh, I can't wait 'till this weekend...
BHD said:
That sound good to me, should add a little more style to the look.
Why do you want a 16 ohm version of the Alpha 15A? I don't understand.
I am very interested in hearing your opinions. No need to wait for the weekend, that is why we have sick days. Get it done on Thursday and Friday, then you could spend the weekend listening.
As the "wings" cannot be modelled in the "Edge" some approximations
would have to be made and the reduced baffle size / width would
affect the modeled FE103 baffle response.
I have no idea what "Edge" is. However i ran some sims on my clunky programming and angled wings on the front and rear and top will work very well. However we cant beat physics so the overall dimensions remain the same except for the fact that there is a greater element of time(due to distance) in the wave cancellation so the overall frontal profile can be reduced if the angled "wings are used on both sides of the baffle. All you do is to sustitute frontal area for depth of the cab.
If you extend the action out in time/phase you end up with two(2) conical horns ,one on the front, one on the back.
ron
would have to be made and the reduced baffle size / width would
affect the modeled FE103 baffle response.
I have no idea what "Edge" is. However i ran some sims on my clunky programming and angled wings on the front and rear and top will work very well. However we cant beat physics so the overall dimensions remain the same except for the fact that there is a greater element of time(due to distance) in the wave cancellation so the overall frontal profile can be reduced if the angled "wings are used on both sides of the baffle. All you do is to sustitute frontal area for depth of the cab.
If you extend the action out in time/phase you end up with two(2) conical horns ,one on the front, one on the back.
ron
Maybe I'm showing my ignorance here
, but by wiring two sixteen ohm woofers in parallel gives you an extra 3db of efficiency and would halve the impedence, making the design of a crossover to an eight ohm full range easier...Or not.
One of the things I got out of your article is that it's hard to match the larger super high efficiency full range drivers with high Qts woofers because the woofers don't have enough efficiency if you don't want the baffles to be freakin' huge. For example, Eminence makes some 32 ohm woofers for paralleled use in bass guitar cabinets - I haven't been able to find any specs on them, but think how efficient four of those paralleled (or 32 ohm Alpha 15A's) would be. AND, they'd be around the same nominal impedence as your full range driver.
Evil, vile temptation... If I can I'll get an early start - I should receive the components tomorrow or Thursday. Maybe I'll get the wood tonight and start cutting...
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