Hi all,
I noticed if that the output segment will be longer the response will be more flat in the region of 600 Hz.
This is the new simulation.
I have increased the filling before the driver and decreased after!
Now seems to be a good response, the f3 frequenzy is little bigger but the response is better
I think to build the spekers with this dimensions!
I noticed if that the output segment will be longer the response will be more flat in the region of 600 Hz.
This is the new simulation.
I have increased the filling before the driver and decreased after!
Now seems to be a good response, the f3 frequenzy is little bigger but the response is better
I think to build the spekers with this dimensions!
Hi all,
I have some other questions:
- The driver is in the middle in each direction, I know that is better avoid this situation.
How much should be the shifting? If I add in the top or bottom a pannel of 15mm, do
you think that can be enough?
- To tune the BSC should I measure the response of the speaker with a microphone?
I have some other questions:
- The driver is in the middle in each direction, I know that is better avoid this situation.
How much should be the shifting? If I add in the top or bottom a pannel of 15mm, do
you think that can be enough?
- To tune the BSC should I measure the response of the speaker with a microphone?
The 10 mm x 100 mm vent slot is a 10:1 ratio, but ~9:1 is considered the limit, so may roll off the bass more than predicted.
You have chosen to build a type of TL with 1/4 WL pipe action with odd harmonics to damp the vent a bit: Resonances of closed air columns
The offsets I posted are measured from the closed end, so basically will have to start over. FWIW, 0.349 is the most common for closed pipes [TL, MLTL] and your 0.5 is popular for the closed cone [MLTQWT, horn]: Resonances of closed air columns
GM
Hi,
Thank you for the help ^^
I try to change the slot ratio, what is a good ratio range?
For the offsets, probably I'am not explained very well what I mean xD. The driver is not in the center of the transmission line. I have tuned the distance to eliminate the first harmonics. In fact L12 (before driver) = 25.2cm, L23 + L34 (after driver) = 42cm. In addition, in the box I will do the line before the driver longer, so I can tune it during the construction of the box.
I mean that the driver is in the center of the baffle (in x and y direction)
Thanks for the book, I'am an engineering therefore I think that can I understand both books, the only problem is the time. (I have not much time).
I would like to try to build this speaker based on some information that I have found in the web and your tips xD
Thank you again!
Thank you for the help ^^
I try to change the slot ratio, what is a good ratio range?
For the offsets, probably I'am not explained very well what I mean xD. The driver is not in the center of the transmission line. I have tuned the distance to eliminate the first harmonics. In fact L12 (before driver) = 25.2cm, L23 + L34 (after driver) = 42cm. In addition, in the box I will do the line before the driver longer, so I can tune it during the construction of the box.
I mean that the driver is in the center of the baffle (in x and y direction)
Thanks for the book, I'am an engineering therefore I think that can I understand both books, the only problem is the time. (I have not much time).
I would like to try to build this speaker based on some information that I have found in the web and your tips xD
Thank you again!
aXp republished it. I have a photocopy of the original and the aXp version (somewhere).. An absoulute gem loaded with fundemental work and findings.
Ou560 comes from.r understanding of baffle step for instance almst always has a picture of his baffle diffraction studies. and is empirically where the number 4560 comes from.
Baffle Diffraction Step
dave
For folks who aren't familiar with these works, 'Elements of Acoustical Engineering' was originally published in 1940, with an updated edition in 1947. 'Acoustical Engineering' - the work to which I referred - was a further expanded and updated version, published in 1957. That's the one I have. The title change can make things a bit confusing.
Hi all,
I have designed a new versions, the dimension is the same of the previous simulation.
I have changed the ratio of the slot, now the dimensions is 70mmx14.3mm and I have changed the position of the first segment, in this way the driver is not in the middle of the baffle. I have read that is better if the driver is not in the middle of the baffle.
What do you think? Now, can work?
I have designed a new versions, the dimension is the same of the previous simulation.
I have changed the ratio of the slot, now the dimensions is 70mmx14.3mm and I have changed the position of the first segment, in this way the driver is not in the middle of the baffle.
I have read that is better if the driver is not in the middle of the baffle.What do you think? Now, can work?
Indeed! Realized too late to edit that you listed the revised version. Both use to be on-line in pdf format, but now can only find the original. Frankly, can't remember it having much in the way of new knowledge that would benefit DIY speaker design.GM
Greets!
I posted ~ 9:1 is considered the limit, so 50/20 = 2.5: 1 makes it well below this.
GM
Thank you very much! Actually it is 70mmx14.3mm, therefore ratio of 4.89:1 But if it is better to have low ratio I will change in 2.5:1!
Therefore do you think that can be a good design?
I start to design the pannel dimension, which type of wood is better? I would like to use birch plywood or MDF, what do you think? I would like to varnish the speaker with a black color.
For the filling, which material do you suggest me? In addition, in the closed part where there are only the BSC filter, connector, ..., I will should fill it with the damping material?
Thank you again
This has been 'bugging' me, especially after googling 'Acoustical Engineering' and yet remembering the revised one had the same title as the original and I was right. No clue why they changed the title, but finally found it on-line [again].
Note the title change is on the title page and being a 1960 rev., they apparently hadn't used up the original binder stock yet, so I guess anybody has one of these is really rare [certain libraries only?] : http://cyrille.pinton.free.fr/electroac/lectures_utiles/son/Olson.pdf
GM
Thank you very much! Actually it is 70mmx14.3mm, therefore ratio of 4.89:1 But if it is better to have low ratio I will change in 2.5:1!
Therefore do you think that can be a good design?
I start to design the pannel dimension, which type of wood is better? I would like to use birch plywood or MDF, what do you think? I would like to varnish the speaker with a black color.
For the filling, which material do you suggest me? In addition, in the closed part where there are only the BSC filter, connector, ..., I will should fill it with the damping material?
Thank you again
You're welcome!
I just used your example, but technically........round is the best, slowly losing acoustic efficiency until at > 9:1 ratio it's now increasingly resistive [like adding stuffing in a vent], so your choice as to what size/shape vent to use. FWIW, I normally used 1.273:1 for rectangular, but if I needed it more like a slit I used up to 12:1 and made the cab a bit bigger to compensate for the loss of low bass around tuning.
If you accurately followed this HR sim, it should be fine: New 3" Full range TL
I always recommend void free plywood [Baltic Birch [BB], apple, marine grade] for most speakers, yours included, but some folks prefer MDF since it's easier to finish, which in this case I recommend HDF.
Getting a furniture finish on BB, etc., plywood is very labor intensive, so recommend google to find all the various forums, websites that specialize in this 'art'. If you just want to stain it, then all I ever did was lightly fine finish sand it, ink stain it, then mix some stain in the varnish, color sand and seal with clear varnish. Of course need to do tests on scraps to find number of stain coats and assuming you want the3D/depth 'look', the amount of stain in the varnish.
Anyway, You'll find that seemingly everybody has there own special way to do any kind of finish, so you're bound to find one you really like and not too hard/expensive. Frankly, to keep my time 'investment' and the price low as practical, I mostly wallpapered or helped the owners wallpaper/decoupage their speakers, equipment racks, bookcases, etc., to match their room or even with inexpensive wood grains. Some folks paid for much nicer, thicker wall papers made from veneers and even wood strips [Bamboo] while others chose some other type of cloth/whatever material, so your tastes, imagination, budget is your only limit.
FWIW/YMMV, if a female is involved, wise to let her choose or at least be a part of the choices, etc., plus I found a surprising number wanted to help with the tedious finishing.
There's lots of threads on how to damp a speaker, but the most popular is lining or stuffing with polyfil and your HR sim should tell you how much you need, then it's just a matter of fluffing it up to fill the area: damping speakers with polyfil - Google Search
I'm not keen on putting electronics in a sealed up cavity full of loose damping. The pioneers used tar, special varnish or similar potting compound to encase them first. Cavities should be filled with sterilized sand or similarly massive material. I normally used Kitty Litter/Oil-Dri or similar.
Good luck with it, hope you post some pictures along the way.
GM
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