I have searched around for some ideas on how to go about stuffing and damping a back loaded horn and just got more confused. I posted in a previous thread that I am working on the recommended enclosure for the FE126E driver. (a hybrid BLH / BR design) I have them near completion but want to get the damping taken care of before I seal them up. Most everyone is saying some damping directly behind the driver is needed. But what about in the horn itself. Should the stuffing be near the driver in the horn or closer to the mouth? Any suggestions would be appreciated.
Thanks
Tim
Thanks
Tim
An externally hosted image should be here but it was not working when we last tested it.
Damping is a vague area of speaker design and the only way to get it right is to experiment. If you take a given design you will find it stuffed differently depending on the system in use, size/shape of room, personal sonic preferences, etc. For example, I have stuffing behind the driver because it reduces a certain nasal sound on vocals, but have no stuffing in the line because I find it boxes the sound in somewhat, though this is at the expense of a little harshness.
My suggestion would be to stuff the line up by 50% if you can, listen to it then add or remove until you get a sound you like. Having said that you'll probably want to change it as the drivers break in or whatever. Use some screws to hold the side panel in place for easy removal and replacement until you think you have found what you need, then glue it down and fill the holes with wood filler.
As for the base I have always found a solid plinth adds depth to the sound so I would fill in that triangular area under the speaker with something heavy like dry sand.
Nice looking speaker btw
My suggestion would be to stuff the line up by 50% if you can, listen to it then add or remove until you get a sound you like. Having said that you'll probably want to change it as the drivers break in or whatever. Use some screws to hold the side panel in place for easy removal and replacement until you think you have found what you need, then glue it down and fill the holes with wood filler.
As for the base I have always found a solid plinth adds depth to the sound so I would fill in that triangular area under the speaker with something heavy like dry sand.
Nice looking speaker btw
Tim,
I don't know this design at all, and I only have built one horn so far, so take my views with a grain of salt. ;-)
I'd put 1mm thick felt into the beginning of the horn, a length of about 90cm from the horn throat. This is supposed to dampen the particle velocity.
You can add damping material to the mouth later, if desired, after the speaker is finished.
Nice looking speaker, BTW. I find these hybrids most interesting, there's a similar design for Lowthers, too. Please keep us updated WRT the sound!
Best regards,
Oliver
I don't know this design at all, and I only have built one horn so far, so take my views with a grain of salt. ;-)
I'd put 1mm thick felt into the beginning of the horn, a length of about 90cm from the horn throat. This is supposed to dampen the particle velocity.
You can add damping material to the mouth later, if desired, after the speaker is finished.
Nice looking speaker, BTW. I find these hybrids most interesting, there's a similar design for Lowthers, too. Please keep us updated WRT the sound!
Best regards,
Oliver
Since Fostex drivers tend to change in character quite a bit during break-in, I recommend you do not use damping anywhere except for the only place where it is absolutely necessary (who says that ??) which IMO is directly behind the driver. After break-in is the perfect time to play with damping and notch filters, if you feel you need them. However, I suspect you want to glue the sidepanels on these babies soon? This seriously impairs the possibilities to do elaborate damping experiments.
Damping is, as Coredump and Ropie already mentioned, something of personal taste but I think you have first to identify the reason why you should want stuffing in the first place. So let the driver break in and then consider your needs.
Let us know how you are progressing.
Damping is, as Coredump and Ropie already mentioned, something of personal taste but I think you have first to identify the reason why you should want stuffing in the first place. So let the driver break in and then consider your needs.
Let us know how you are progressing.
Tim,
I made a similar loudspeaker (without BR) long ago.
As I see from the photo, you need to place some absorbment on the area just behind the driver, for the mid frequencies not to strike back, on the speaker unit.
Then, the rest of the champer should be treated ,such as, no resonances, would be reproduced from the unit and the horn.
Usually wall treatment is enough,maybe you will add some more.
Officialy no stuffing is required for the horns, but these are close to transmission lines.
I treated mine as a horn.
Your project though, is quite complicated with the incorporation of the PR.
Needs a lot of theoretical support, because the coupling champer of the horn is used also as a resonance champer of the port.
Major problem at those projects (without PR), is the balance between the direct bass of the unit and the reinforced bass of the horn.
Anyway maybe the best you should do is to make the side panel removable for your testings.
Nice job, good luck.
Anastasio.
I made a similar loudspeaker (without BR) long ago.
As I see from the photo, you need to place some absorbment on the area just behind the driver, for the mid frequencies not to strike back, on the speaker unit.
Then, the rest of the champer should be treated ,such as, no resonances, would be reproduced from the unit and the horn.
Usually wall treatment is enough,maybe you will add some more.
Officialy no stuffing is required for the horns, but these are close to transmission lines.
I treated mine as a horn.
Your project though, is quite complicated with the incorporation of the PR.
Needs a lot of theoretical support, because the coupling champer of the horn is used also as a resonance champer of the port.
Major problem at those projects (without PR), is the balance between the direct bass of the unit and the reinforced bass of the horn.
Anyway maybe the best you should do is to make the side panel removable for your testings.
Nice job, good luck.
Anastasio.
Thanks for the replies. The damping that is installed already is just some thin asphalt "peel & stick" stuff to add mass to the internal pieces. I have clamped on the side and tried some stuffing in different places with not much effect. (just less bass) I think from the replies I might just leave the foam behind the driver and make the side panel removable until the driver breaks in, then tinker with the stuffing.
Thanks again!
Tim
Thanks again!
Tim
some RTA
Considering the inclusion of a BR, I guess it will be a good thing to use an RTA and a reliable mic when the break in is enough and the (about) final room positioning is decided. Then you will be able to use absorption creativly for achieving a judicious in room balance in the bass to midbass region.
Considering the inclusion of a BR, I guess it will be a good thing to use an RTA and a reliable mic when the break in is enough and the (about) final room positioning is decided. Then you will be able to use absorption creativly for achieving a judicious in room balance in the bass to midbass region.
I was asking the same question some 2 months ago when I finished my Horn. After alot of work and experimentation I ended up using no lining or any stuffing in any part of the horn, even behimd the driver. This is due to the fact that whatever I added behind the driver in the compression chamber subtracted realism and speed from the sound. Moreover, let the speakers break in for more than 100 hours before you glue the sides on.
Having made a few back horn cabinets (using the Fostex 168 E Sigma) with nothing in the horn path, I tried one with a cork lining through the path. Heard, was a quieter/darker background. Cork only absorbs the upper treble. With all the wind blowing around in a horn chamber, I speculate some whispering hissing is created. In the Nagaoka designs of Fostex, some sound absorbing material is added at the last bend before the horn's mouth. This undoubtedly absorbs these treble wind created sounds.
First of all I have to say what a great forum this is, lots of great information!
Second, I got both of the speakers put together with just the damping behind the driver in one and the on in the above picture. If you can believe it I have the sides duct taped on to give them a listen. The bass really is pretty impressive (this is my first BLH and full range project, I haven't even ever heard any before) I am going to let them get good a broken in and then try out your suggestions!
Thanks for the info!
Tim
Second, I got both of the speakers put together with just the damping behind the driver in one and the on in the above picture. If you can believe it I have the sides duct taped on to give them a listen. The bass really is pretty impressive (this is my first BLH and full range project, I haven't even ever heard any before) I am going to let them get good a broken in and then try out your suggestions!
Thanks for the info!
Tim
Nice horns
Hello!
I consider making these speakers myself. I have only built subwoofers and low-quality bassreflex designs before, and never even heard a hifi horn! The only way I can find out how they sound is to build a pair of my own.
I just want any oppinions about the effect of bitumen in horns, just like Skitch72 already "installed".
This is btw my first post!
Hello!
I consider making these speakers myself. I have only built subwoofers and low-quality bassreflex designs before, and never even heard a hifi horn! The only way I can find out how they sound is to build a pair of my own.
I just want any oppinions about the effect of bitumen in horns, just like Skitch72 already "installed".
This is btw my first post!
With the Fostex 168 E Sigma, which is about my favorite Fostex driver, having heard several, but not all Fostex drivers (they make so many), I built the zHorn design. I'm satisfied with the performance of this driver in this box, wishing someday perhaps to try it in a wide baffle enclosure. I've some Jordan JX92s that I've first had in a narrow baffle, then like better in the wide baffle. A wide baffle makes for easy room placement and a huge image.
I have used cork to line, but think some felt would do well. The horn path should only amplifiy the bass, and to absorb and disrupt the mid and treble through the path can only make for an overall cleaner sound. Cleaner, because horns do leak some of the midrange which can only be a distorted midrange.
I have used cork to line, but think some felt would do well. The horn path should only amplifiy the bass, and to absorb and disrupt the mid and treble through the path can only make for an overall cleaner sound. Cleaner, because horns do leak some of the midrange which can only be a distorted midrange.
FE126E Recommended BLH
Tuning the Horn resonance ? - Help needed
I built the Fostex recommended BLH/BR hybrid for the FE126e on a weekend a couple of months ago. With the drivers now reasonably broken in, I have tried some tuning.
Damping
I have added thick felt (1/2") behind the driver to dampen reflections back through the driver. OK so far.
I tried to add light stuffing in the CC (staying clear of the throat). This seemed however to create a more "boomy" sound around 100Hz, and was removed.
Horn resonances
When using a signal generator and my ears as test instrument, there is a very pronounced horn resonance at 110Hz . This is fairly narrow, about 90-120Hz (high Q). The next horn resonances are in the 200-300Hz range, but these are less pronounced.
The resonance at 110Hz seems to have an amount of decay, and thus prone to emphasize a "boom" at this frequency. The other effect is a possible dip in the level around 150Hz.
My observations seem to be very similar to the Stereophile measurements for the HornShoppe horn:
http://stereophile.com/loudspeakerreviews/104horn/index4.html
Is it possible to tune the Q of the horn resonance?
This is where I could need some guidance.
Would it be possible to apply some sort of damping or other adjustments to tune the sharpness of the horn resonance ???
---
PS: I will probably build the Frugel-Horn once the design is finalized.
SB.
Tuning the Horn resonance ? - Help needed
I built the Fostex recommended BLH/BR hybrid for the FE126e on a weekend a couple of months ago. With the drivers now reasonably broken in, I have tried some tuning.
Damping
I have added thick felt (1/2") behind the driver to dampen reflections back through the driver. OK so far.
I tried to add light stuffing in the CC (staying clear of the throat). This seemed however to create a more "boomy" sound around 100Hz, and was removed.
Horn resonances
When using a signal generator and my ears as test instrument, there is a very pronounced horn resonance at 110Hz . This is fairly narrow, about 90-120Hz (high Q). The next horn resonances are in the 200-300Hz range, but these are less pronounced.
The resonance at 110Hz seems to have an amount of decay, and thus prone to emphasize a "boom" at this frequency. The other effect is a possible dip in the level around 150Hz.
My observations seem to be very similar to the Stereophile measurements for the HornShoppe horn:
http://stereophile.com/loudspeakerreviews/104horn/index4.html
Is it possible to tune the Q of the horn resonance?
This is where I could need some guidance.
Would it be possible to apply some sort of damping or other adjustments to tune the sharpness of the horn resonance ???
---
PS: I will probably build the Frugel-Horn once the design is finalized.
SB.
thin sound absorbing material?
Hi, I've built the recommended enclosures for FE166 but I'm not sure what to use for the "thin sound absorbing material". The plans recommend putting this stuff behind the speaker and in the bottom of the cabinet. I've had a look around the hardware stores for some thin dense insullation but I'm not sure if I found anything that would work. Here's a link to the plans I used:
http://www.fostexinternational.com/docs/speaker_comp/pdf/recom_enclose/166e_enclrev.pdf
Hi, I've built the recommended enclosures for FE166 but I'm not sure what to use for the "thin sound absorbing material". The plans recommend putting this stuff behind the speaker and in the bottom of the cabinet. I've had a look around the hardware stores for some thin dense insullation but I'm not sure if I found anything that would work. Here's a link to the plans I used:
http://www.fostexinternational.com/docs/speaker_comp/pdf/recom_enclose/166e_enclrev.pdf
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