Hi Roelof,
Don't blame your self for poor understanding of my simple drawing: You are of course right: the drawing is very vague...
I checked the drawing again and found one faulty number, now revised. This can be seen in the slightly updated picture 1(1) here below.
My simple drawing is just an example how to fold the HR simulation if happen to be a straight pipe, i.e. a T-TQWP a.k.a. T-TQWT.
The suggestion was to pick one of the L length's between 2,6 m to 3 m.
As this length is unknown, I left out the vertical dimensions to be a calculation exercise for any user of this particular drawing.
For a first trial: use L/4 for the internal height and calculate if all sums up to within about 5 % of the chosen L, IMO good enough.
b
1(1)
Attachments
Herz subwoofer
Hi B,
Thanks again for the info. I can build that box if I can work out where the supports must be. Please excuse me, I am a retired electrical eng. and not an audio guru at all. This is my first speaker box building excersize. What is "L" If I take it as 2,8 m and make the inside of the box 700mm. That just looks like a good guess to me ?
Thanks again
Roelof
Hi B,
Thanks again for the info. I can build that box if I can work out where the supports must be. Please excuse me, I am a retired electrical eng. and not an audio guru at all. This is my first speaker box building excersize. What is "L" If I take it as 2,8 m and make the inside of the box 700mm. That just looks like a good guess to me ?
Thanks again
Roelof
Hi Roelof,
I guess we have a similar background and maybe age too..2.8 m length is a good choice,see the pictures where also a OD.Offset driver TL is plotted for comparison.
This could be a good option to use if the speaker is placed closely to a short wall corner when over-emphasizes of low end modal FR is expected.
b
Attachments
Hertz subwoofer
Hi Roelof,
Yes they are all flat vertically oriented pieces dividing the box in half looking from the face of the speaker where the volume loss can be ignored if only occupying a couple of percents of the total internal volume.
b
Hi Roelof,
Yes they are all flat vertically oriented pieces dividing the box in half looking from the face of the speaker where the volume loss can be ignored if only occupying a couple of percents of the total internal volume.
b
Hi B, Sorry to be a pain but some more questions: The booklet that comes with the speaker says that there should be 50mm gap between the rear of the speaker and the box to allow for air movement through the hole in the magnet.? The devider going up to the sub L23 seems to stop very close to the sub. Your drawing shows lines going up to the back of the magnet. Are these flux lines? there is no mechanical piece on the speaker as indicated on the drawing? If you leave the dotted lines out, that is what the speaker looks like. Thanks for the effort, Roelof
Hi Roelof,
The driver rear clearing gap is increased (needed for air cooling of the voice coil) and also the distance to the close divider: See the picture.
Flux lines? No,There may be different versions of this driver, maybe you are referring to the thick plastics that seems to cover the aluminum alloy basket or in the picture, the red line that is drawn ?b
Attachments
Hi B, thanks again for the help. My speaker does not have the plastic or aluminium outside cover/support as in your picture. The structure for the magnet is there and the voice coil(s) are fitted around the magnet. That is it. I will try to scan the picture or photograph the speaker and send it to you one way or the other. I am not too clear on how to add pictures to the message, yet.
Regards , Roelof
Regards , Roelof
Hi Roelof,
Thats what I thought too, You may also have a driver version with other T/S parameters? Attaching pictures is very easy to do, just click the 'Manage Attachments button' and be ready to upload your pictures in a valid format/ file extension. Looking forward to see your pictures showing the driver without cosmetics that has nothing to do with the possible acoustic performance at all.
b
Box subwoofer
Hi B, I have changed your design slightly, the material around here is 16,18 and 22mm. I decided to go for 22mm MDF. The bracings will be 16mm MDF. I have modified the sizes so that I still have the 80mm channel All the way. Will send you the modified drawing if you are interested.
Please tell me about the removeable cover indicated in one of your drawings.
What changes in the sound/volume is the result ?
And buy the way, I changed the depth of the box to 330mm to give me a bit more meat to mount the driver on.
If the above meats with your approval, please let me know.
Kind regards
Roelof
Hi B, I have changed your design slightly, the material around here is 16,18 and 22mm. I decided to go for 22mm MDF. The bracings will be 16mm MDF. I have modified the sizes so that I still have the 80mm channel All the way. Will send you the modified drawing if you are interested.
Please tell me about the removeable cover indicated in one of your drawings.
What changes in the sound/volume is the result ?
And buy the way, I changed the depth of the box to 330mm to give me a bit more meat to mount the driver on.
If the above meats with your approval, please let me know.
Kind regards
Roelof
Hi Roelof,
Sorry for delaying this thread. 
Your changes of the box is OK.If you remove the cover (needed for accessing the driver) the driver/box output terminates at slightly different places and the box is turned into a tapered Offset Driver TL.
The total length will be shorter with the 'airways' termination at about the driver radius distance.
You can see the OD response in light gray/red colors in the HR simulation compared to the T-TQWT(black and red colors).:up
Its a matter of taste if you like the OD TL response, but IMO a sub with a sloping FR sounds often smoother when placed close to any of the room corners if compared to one with a straighter FR.
If you have modified my drawings why not post yours here at diyAudio?
b
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