| weidok |
Hello
I planning to build a ML TL with the fullrange 6"speaker from Fostex FE 167 E.
The dimensions will be height= 39" depht= 11'and wide = 7 1/2" and a port which will be round 3" and 2 1/2" long 1 1/4" from the bottum,
BSC will be L= 0,3 mH, C= 3,9 uF and R=4,7 ohm.
do i need any other correction network?
who has any ideas and who can help me ? |
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| MJK |
You will probably need a Zobel to make the BSC circuit work correctly. Where did you get the values for the circuit? The values don't look correct to me, maybe I am wrong.
Hope that helps, |
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| weidok |
Martin
I used a crossoverdesign exel spreadsheet 2.03 from internet tried to design a bsc network without a zobel..
What do you suggest for a better bsc and zobel..
are the demensions correct??
ytzen |
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| MJK |
| quote: | | I used a crossoverdesign exel spreadsheet 2.03 from internet tried to design a bsc network without a zobel.. |
Why leave out the Zobel? The Zobel is what makes the BSC circuit resposne predictable and adjustable at high frequency.
| quote: | | What do you suggest for a better bsc and zobel.. |
The Zobel and BSC circuit I used for my ML TQWT should be closer to the correct values for your geometry. The FE-164 and FE-167E are similar so I would start with values as follows.
Zobel :
6.8 uF in series with 10 ohms.
BSC :
2, 3, 4, or 5 mH inductor (probably a 3 mH would be best) in parallel with a 4 to 8 ohm resistor.
The BSC circuit would be adjusted base on your amp and room placement. Without measurements all you can do is try different values until you get the combination that works best. I think your 0.3 mH inductor is diffinitely too small and I don't think the FE-167E will need the 3.9 uF cap to help the high end. The high end should be adequate. Again, trying the values is the final test.
| quote: | | are the demensions correct?? |
I don't know, how did you arrive at these dimensions? Do you have some simulation results? Without some analysis I don't know if this is a good geometry or not. |
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| weidok |
Martin
The geometry is from a ml tl with the Fostex FE 168 sigma ?
I see now the height must be 40 "
and the port is to short i think !!!
Just saw Rob Brines has even better plans with the same speaker that i want to use.. and yes he also uses a zobelnetwork
Sorry but i have no simulation results at all |
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| MJK |
| I am sure Bob Brines' design is very good. I think it would be a safe bet to follow his plans to the letter. I have read many good reviews and comments about his FE-167E ML TL design. You cannot go wrong with his design. |
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| Bob Brines |
Interestingly enough, my latest set of MLTL's for the FE167E does not use a zobel. Martin has been using a cap across the BSC filter, which changes the step filter into a low Q notch filter. The reason for doing this is to bring back some of the high frequency response that goes away with the step filter.
I found, at least with my cabinet, that by removing the zobel, the rising impedance of the driver does indeed cause the BSC filter to fail at high frequency and bring up the top end. This may be a little hot for some, but since I listen somewhat off-axis anyway, it is about right. 2mH||6ohm.
I'm not suggesting this is a silver bullet, but it does seem to work in this case.
Black=On Axis, Red=30deg off, Blue=60deg off, Gray=unsmoothed on axis
Bob |
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| MJK |
| I have also tried removing the Zobel and notice the same increased high frequency response that is shown in your plots. This can be very effective. The only downside is the loss of adjustability and the changing response as you adjust the parallel resistor in the BSC circuit. If it works then that is the simple and low cost (less parts) solution. But leaving the Zobel in, and using a cap in the BSC circuit, allows for a greater amount of adjustability in the high frequenct response. Either method can work well and they are easy circuit configurations to try. |
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| weidok |
Martin and Bob,
Thanks i will try both options with and whitout a zobel..
Where can i find more reviews with the Fostex Fe 167 E |
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| planet10 |
| quote: | Originally posted by MJK
FE-167E ML TL design |
I've heard a couple variations of Bob's ML-TL and these are good... a no brainer to just build his design.
dave |
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| weidok |
Ok so i just ordered the speakers "Fostex"FE 167 E
form germany..
I'll use the demensions from BOb's FT 1600 mk II
the port will be round 3 " and about 41/4" long
Instead of using a pvc tube i am thinking using wooden rings
to eleminate vabrations of a tube |
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| Bob Brines |
| quote: | Originally posted by weidok
Ok so i just ordered the speakers "Fostex"FE 167 E
form germany..
I'll use the demensions from BOb's FT 1600 mk II
the port will be round 3 " and about 41/4" long
Instead of using a pvc tube i am thinking using wooden rings
to eleminate vabrations of a tube |
Remember that those are outside dimensions and assume 3/4" material. There is also a 1/4" cement board lining. The actual pipe dimensions are 40x8.5x8.5.
Bob |
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| weidok |
Bob,
Cement board can you explain that i really don't know what that is ??
Must i double the top ...
And are other users with the Fostex Fe 167 E or not ???
Please let me (us) know about and reply on this post ? |
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| Timn8ter |
| Cement board here in the US is a ceramic based material 1/4" thick that is used in (typically) home construction to put tile on, such as bathrooms, kitchens, etc.. I've used it in building TLs and highly recommend it to reduce cabinet vibrations. Other materials can be substituted if it is the same thickness, or you account for the thickness in your internal volume. Granite tile, ceramic tile or other types of floor tile can be used. A good construction adhesive can be used to attach it to the inside of the cabinet panels. |
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| Bob Brines |
| quote: | Originally posted by weidok
Bob,
Cement board can you explain that i really don't know what that is ??
Must i double the top ...
And are other users with the Fostex Fe 167 E or not ???
Please let me (us) know about and reply on this post ? |
Timn8ter has it right. The brand I use is "Hardi-Backer", though this information is probably of little use outside North Amaerica. I used to recommend ceramic tiles, but the Hardi-Backer is much easier to cut to size.
Yes, double the top and line it with cement board, tile, whatever. You will be amazed at the difference this makes in the amout of vibration -- and sound -- coming from a thin top panel.
Bob |
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| Luke |
| Cement board seems very brittle, can you cut it with normal table saw etc. What about glue, is PVA ok for this stuff? |
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| Leeuwarden |
| Sounds like it could be "beton-multiplex". It is available in a "bouwmarkt". It is a lot more expensive than normal multiplex. |
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| Bob Brines |
| quote: | Originally posted by Luke
Cement board seems very brittle, can you cut it with normal table saw etc. What about glue, is PVA ok for this stuff? |
Get a diamond abrasive saw blade for your table saw. Gets dust everywhere, but cuts nicely.
I use Liquid Nails panel adhesive.
Bob |
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| Luke |
Thanks Bob
Diamond abrasive saw, ouch that sounds spendy:bigeyes:
Might try find a diamond jigsaw blade :D
cheers arthur |
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| peterr |
| quote: | Originally posted by Leeuwarden
Sounds like it could be "beton-multiplex". It is available in a "bouwmarkt". It is a lot more expensive than normal multiplex. |
It is certainly not "beton-multiplex". It is more like fermacell which is used as an alternative to waterproof "gipsplaat". You can buy fermacell at the professional building material shops like "Bouwmaat" not sure about diy shops. |
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| weidok |
| quote: | Originally posted by Bob Brines
Yes, double the top and line it with cement board, tile, whatever. You will be amazed at the difference this makes in the amout of vibration -- and sound -- coming from a thin top panel.
Bob |
Thanks Bog,
i double te top ..
i just made the drawings used 7/8 " (22 mm) MDF
Instead of using a pvc tube i am using wooden rings
to eleminate vabrations of a tube..
Must i do something about the vibrations from the frame of Fostex
i read other users of fullrange speakers did it to?
Greetings Weidok
Hee Leeuwarden welcome.. worldwide... |
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| planet10 |
| quote: | Originally posted by weidok
Must i do something about the vibrations from the frame of Fostex
i read other users of fullrange speakers did it to? |
I've not used a driver yet that doesn't benefit from some judicial use of DuctSeal (the Phy-HP being the only driver i've touched that didn't actually have anywhere to put it). I won't install a stamped frame driver without some duct-seal treatment.
Morse probably had some interesting comments about the series of small tweaks he did to his.
dave |
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| Morse |
Hi Dave!
Funny you should mention the rope caulk tweak now - I just applied it to my first "post workshop move" speakers a couple of days back. As expected, it cleaned up the midrange nicely, as well as removing a bit of an 'edge' to the upper midrange (gotta be a basket resonance at work there).
The "felt on the back of the magnet" tweak had a more subtle, but still useful impact, so it's a 'must do' on any speaker with a ferrite magnet IMHO. I've run out of felt padding momentarily though, so the "felt on the insides of the basket legs" tweak will wait until next week.
Interestingly, one thing happened in this project that proved a complete surprise (though it shouldn't have): the improvised mounting for the binding posts proved a wholly inadequate solution (all I had handy at the time of construction was some perfboard and soft PVC type plastic to place as a gasket). Replacing those with proper 1/4" thick plywood mounts that I affixed with polyurethane glue yielded a substantial improvement in bass potential from these tiny little 5.6L RS40-1197 BR/folded TL hybrids. Midrange clarity also apparently suffered from the resonances that these improvised mounts introduced, since there was an increase in image depth accompanying this change. I'd expected a small improvement in performance, but the results of this experience make me wonder about the potentially deleterious effect of the "weak wall" that many cheap mounting cups for speaker connectors constitute. On "no holds barred" projects, I shall continue my practice of using binding posts with long enough shafts to be used without any mounting plate assembly at all - just a hole for each post through the cabinet.
One last thought in the "cheap but critical tweaks" department is that on office speakers some thought must be given to the acoustic properties of the desk or table they're to be sat upon. The RS40-1197's have enough bass now that they can really make the top of that desk resonate (unpleasantly) and muddy up the sound. This has (mostly) been cured by using 3/4" thick rubber feet (3 per cab) on the bottoms of the speakers to act as a decoupler.
Hope I didn't put anyone to sleep! :-) Oh well, time to get back to grading papers....
All the best,
Morse |
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| weidok |
Tanks Morse
So i wille use the rope caulk tweak , it will clean up the midrange nicely.
And mounting binding posts on the gasket ?
Do you have any pictures of it so i understand it better? |
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| planet10 |
| quote: | Originally posted by weidok
So i wille use the rope caulk tweak , it will clean up the midrange nicely. |
If you can find ductseal you will be further ahead... rope caulk tends to harden over time and the benefits of the tweak as well.
dave |
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