Fostex BK12m speakers....finally done!

[Hari Iyer]

See how it dips below 200hz? It still sounds a wee too thick in the lower mids and sometimes I wish it didn't, at other times I don't notice...

--G0bble

Thanks for the inputs. Did you try adding a baffle step compensation. This will allow the mid-bass to be in level with the mids and the highs. Try this out if you are unhappy with the mid-bass. I can see from the FR curve that the roll-off from 200Hz to 100Hz is quite gradual and hence will be pleasing to hear and fatigue free. Adding a BSC would add another 3 to 4dB to the mid-bass response. Will be eager for an update from you after the modification. If you require help in calculation for the value of the 'Resistor' & 'Inductor' do let me know and if I can be of help.

Cheers,

 

[gobble]

Thanks for the inputs. Did you try adding a baffle step compensation. This will allow the mid-bass to be in level with the mids and the highs. Try this out if you are unhappy with the mid-bass. I can see from the FR curve that the roll-off from 200Hz to 100Hz is quite gradual and hence will be pleasing to hear and fatigue free. Adding a BSC would add another 3 to 4dB to the mid-bass response. Will be eager for an update from you after the modification. If you require help in calculation for the value of the 'Resistor' & 'Inductor' do let me know and if I can be of help.

Cheers,

Will it reduce efficiency of the speaker? I run a 8.5W tube amp thats why I am concerned. Now that I use a sub is it worth it? Or will the ability to lower the sub crossover from the current 65-68hz to further down improve anything? ideally I would like to tame the 2-4khz range as well - just slightly and listen for improvments.

If you look at the spectral graph you will see the blue lines radiating upwards - they look like untamed resonance lacking sufficient decay from the lower mids onwards. It is especially pronounced at the resonant frequence of 50hz. I think reducing that will provide some benefits as well? How can we do that?

--G0bble

 

[soundnovice]

Will it reduce efficiency of the speaker? I run a 8.5W tube amp thats why I am concerned. Now that I use a sub is it worth it? Or will the ability to lower the sub crossover from the current 65-68hz to further down improve anything? ideally I would like to tame the 2-4khz range as well - just slightly and listen for improvments.

If you look at the spectral graph you will see the blue lines radiating upwards - they look like untamed resonance lacking sufficient decay from the lower mids onwards. It is especially pronounced at the resonant frequence of 50hz. I think reducing that will provide some benefits as well? How can we do that?

--G0bble

i read fostex drivers 6.5" (fe166) and 8"(fe206) are known to sound bright. people have tamed the bright mid/uppermid with some equalizer ckt. may be u will need to search on diyaudio.com

 

[Hari Iyer]

Will it reduce efficiency of the speaker? I run a 8.5W tube amp thats why I am concerned. Now that I use a sub is it worth it? Or will the ability to lower the sub crossover from the current 65-68hz to further down improve anything? ideally I would like to tame the 2-4khz range as well - just slightly and listen for improvments.

If you look at the spectral graph you will see the blue lines radiating upwards - they look like untamed resonance lacking sufficient decay from the lower mids onwards. It is especially pronounced at the resonant frequence of 50hz. I think reducing that will provide some benefits as well? How can we do that?

--G0bble

I agree with soundnovice that the Fostex will sound a tad bright unless you use some kind of compensation / equalization for the mid-freq region. Adding a BSC will help to reduce the mid-freq by around 3 to 4 dB there by giving an illusion of increased mid-bass freq. If you use a 18SWG or 16SWG wire for the inductors then the issue of sensitivity drop will also vanish as such high guage wire would have a reistance of not more than 0.2 ohms. Also i will recommend to use high quality/wattage metal film resistors instead of wire wound resistors here. Hence the overall drop will be less than 0.4dB which should be okay. Also the cost of doing this is very minimal considering an active equalizers.

Cheers,

 

[corElement]

I was doing some reading on other forums and from what others have mentioned, a lot of people seem to say the 4-5" fostex handles detail in sound better than the 6 and 8. So it was a good idea to put it in a TL box. You're getting the detail while box gives you the bass it lacks.

 

[soundnovice]

I was doing some reading on other forums and from what others have mentioned, a lot of people seem to say the 4-5" fostex handles detail in sound better than the 6 and 8. So it was a good idea to put it in a TL box. You're getting the detail while box gives you the bass it lacks.

yes. infact more number of speakers/boxes/plans exist for 3" (fe83en/ff85wk), 4"(fe103en/fe126en/ff105wk) than 6" or 8" drivers. however anything above 3" lacks sparkle in the top end, making a tweeter must to reach 20khz. since adding tweeter is easier than adding woofer to a full ranger, again i prefer 5" or 6" or even 8"

 

[gobble]

i read fostex drivers 6.5" (fe166) and 8"(fe206) are known to sound bright. people have tamed the bright mid/uppermid with some equalizer ckt. may be u will need to search on diyaudio.com

Hmm yes my speakers occassionaly give me the feeling they could be tamed, but now I am so used to it.

I agree with soundnovice that the Fostex will sound a tad bright unless you use some kind of compensation / equalization for the mid-freq region. Adding a BSC will help to reduce the mid-freq by around 3 to 4 dB there by giving an illusion of increased mid-bass freq. If you use a 18SWG or 16SWG wire for the inductors then the issue of sensitivity drop will also vanish as such high guage wire would have a reistance of not more than 0.2 ohms. Also i will recommend to use high quality/wattage metal film resistors instead of wire wound resistors here. Hence the overall drop will be less than 0.4dB which should be okay. Also the cost of doing this is very minimal considering an active equalizers.

Cheers,

Only if you make it easy for and build me something to plug in. I would rather invest the time in building my new speaker cabinet.

I was doing some reading on other forums and from what others have mentioned, a lot of people seem to say the 4-5" fostex handles detail in sound better than the 6 and 8. So it was a good idea to put it in a TL box. You're getting the detail while box gives you the bass it lacks.

5" driver is considered optimal for mids and above. And yes I too read that TL can enhance the quality of bass, so TL build may not sound like my bass reflex.

--G0bble

 

[corElement]

Hmm yes my speakers occassionaly give me the feeling they could be tamed, but now I am so used to it.


Only if you make it easy for and build me something to plug in. I would rather invest the time in building my new speaker cabinet.



5" driver is considered optimal for mids and above. And yes I too read that TL can enhance the quality of bass, so TL build may not sound like my bass reflex.

--G0bble

Gobble, an easy quickfix prior to making changes to the speaker, is trying out a hyperlitz cable with solid ofc solid cores as your IC. ofc Hyperlitz solid core cable sound is much softer than multithread ofc. Atleast that's what Atish and I noticed with my jamo's. They're super bright speakers which i was going to modify with bafflestep compensation and what not to tame the brightness but didn't have to bother when i connected the hyperlitz IC between the source and amp. The multithread IC cable was a weak link in the chain for it's synergy.

Perhaps you can borrow one from someone and see how it sounds?

 

[gobble]

Sound softer? I prefer solidity of image focus.

--Sent from mobile on a crappy keyboard. Pls excuse typos.

 

[corElement]

From what I've heard of the 166 series they honestly don't need to be made softer than they are. But you mentioned somewhere you found it a little bright? I dunno I think I may be getting confused regarding who's saying what, so don't mind me