Yeah, Ted always refers to them as frequency compensation, not BSC.
I've heard it applied to the 8 litre reflex and it does work, filling out the bass and improving overall balance on that particular design. The 48" MLTL seems to be well enough balanced without it, although I do use them close to the wall. Out in the room, you may have other preferences.
Colin
I've heard it applied to the 8 litre reflex and it does work, filling out the bass and improving overall balance on that particular design. The 48" MLTL seems to be well enough balanced without it, although I do use them close to the wall. Out in the room, you may have other preferences.
Colin
Colin said:
Without the compensation circuit, the power curve looks like a band pass filter. with the circuit, it looks like trade-off some efficiency to gain greater power bandwidth. At least this is the trend analysis shows. I've just begun to try some things out with other drivers.
JX92S Frequency Compensation
To understand what frequency compensation (or baffle step comp) can do to help out the JX92S (or any driver in a box for that matter), take a look at the data from my JX92S Mini-monitor as measured by Dennis Murphy at the 2001 Washington, DC DIY speaker meeting. Observe the plots at the bottom of the page on the 2001 Atlanta DIY best of show speaker (my Mini-monitor) at this link:
http://murphyblaster.com/content.php?f=DIY_2001.html
Room effects limit the accuracy of these data to 200 Hz and above. You can see a 3-4 dB and up fall off in the 200-800 Hz range which is flatten by the BSC circuit.
For what it is worth, the 2004 Atlanta DIY Best of Show speaker (this one with a JX92S and an Aurum Cantus G2si ribbon tweeter) addresses both the BSC issue and any roughness of the JX92S in the treble range. You can see data and read my report at:
http://www.creativesound.ca/pdf/JX92SG2siDesignPak.pdf
Notice that the version with the ribbon extends between 200 to more than 30,000 Hz within +/- 2.5 dB. Quite nice!
Jim
To understand what frequency compensation (or baffle step comp) can do to help out the JX92S (or any driver in a box for that matter), take a look at the data from my JX92S Mini-monitor as measured by Dennis Murphy at the 2001 Washington, DC DIY speaker meeting. Observe the plots at the bottom of the page on the 2001 Atlanta DIY best of show speaker (my Mini-monitor) at this link:
http://murphyblaster.com/content.php?f=DIY_2001.html
Room effects limit the accuracy of these data to 200 Hz and above. You can see a 3-4 dB and up fall off in the 200-800 Hz range which is flatten by the BSC circuit.
For what it is worth, the 2004 Atlanta DIY Best of Show speaker (this one with a JX92S and an Aurum Cantus G2si ribbon tweeter) addresses both the BSC issue and any roughness of the JX92S in the treble range. You can see data and read my report at:
http://www.creativesound.ca/pdf/JX92SG2siDesignPak.pdf
Notice that the version with the ribbon extends between 200 to more than 30,000 Hz within +/- 2.5 dB. Quite nice!
Jim
Hi Jim,
Your data seems to match my initial analysis. I think people call this BSC just for convenience. In reality, since the values recommended varies with box volume and not baffle dimensions, it is not really a BSC.
Your data seems to match my initial analysis. I think people call this BSC just for convenience. In reality, since the values recommended varies with box volume and not baffle dimensions, it is not really a BSC.
Re: JX92S Frequency Compensation
Jim,
I know that the data for the JX92S alone had some ripple at the high end, and also some rolloff at 30deg off axis. What is the audible difference between you JX92S system and the one with the Aurum Cantus G2si ribbon tweeter? Does the 30deg off axis response look that different?
Jim Griffin said:
Jim,
I know that the data for the JX92S alone had some ripple at the high end, and also some rolloff at 30deg off axis. What is the audible difference between you JX92S system and the one with the Aurum Cantus G2si ribbon tweeter? Does the 30deg off axis response look that different?
Jordan with Ribbon Dispersion
"I know that the data for the JX92S alone had some ripple at the high end, and also some rolloff at 30deg off axis. What is the audible difference between you JX92S system and the one with the Aurum Cantus G2si ribbon tweeter? Does the 30deg off axis response look that different?"
I don't have a 30 degrees off plot of the ribbon version. But in the pdf on the Creative Sound Solutions site that I referenced earlier in this thread you can see that the 15 degrees off axis performance is very flat.
Listening to the 'with ribbon version' reveals very wide dispersion--inherent with the ribbon tweeter. You don't have to toe-in the speakers to get the best sound as you would with the JX92S covering the treble range. Of course the JX92S is intended to have a 15 degrees toe-in for best treble sound but it is clear that the beaming of the radiator rolls off any high frequency dispersion. The ribbons don't have that issue until a much wider angle.
I would say that if you wish to have excellent dispersion yet capture the magic of the JX92S, then the speaker with the ribbon tweeter would give you the best of both worlds.
Jim
"I know that the data for the JX92S alone had some ripple at the high end, and also some rolloff at 30deg off axis. What is the audible difference between you JX92S system and the one with the Aurum Cantus G2si ribbon tweeter? Does the 30deg off axis response look that different?"
I don't have a 30 degrees off plot of the ribbon version. But in the pdf on the Creative Sound Solutions site that I referenced earlier in this thread you can see that the 15 degrees off axis performance is very flat.
Listening to the 'with ribbon version' reveals very wide dispersion--inherent with the ribbon tweeter. You don't have to toe-in the speakers to get the best sound as you would with the JX92S covering the treble range. Of course the JX92S is intended to have a 15 degrees toe-in for best treble sound but it is clear that the beaming of the radiator rolls off any high frequency dispersion. The ribbons don't have that issue until a much wider angle.
I would say that if you wish to have excellent dispersion yet capture the magic of the JX92S, then the speaker with the ribbon tweeter would give you the best of both worlds.
Jim
Re: Jordan with Ribbon Dispersion
It would be interesting to see a 30deg off axis plot. I also looked at the Aurum site, and their waterfall plot of the driver does not show the decay time in msec as usual, but rather indicates "periods", do you know what time scale "periods" refer to?
Jim Griffin said:
It would be interesting to see a 30deg off axis plot. I also looked at the Aurum site, and their waterfall plot of the driver does not show the decay time in msec as usual, but rather indicates "periods", do you know what time scale "periods" refer to?
RLC phase correction is the best
If you look up the phase difference with JX92S. You will find there is some 300 degrees apart between 20Hz and 20 kHz. So, I used RLC to correct the phase. It works very well with 0.5mH, 4ohm and 8-12 uF in parallel and the whole circuit in series the 92S. Enjoy the difference🙂. you will find to add an impedence correction circuit at the input of speaker to balance the impedence will improve the sound too.
I do not want to write too much for someone does not read. So e-mail to me at erictoucan@yahoo.co.uk. We can talk in more details.
Do not be afraid of correction circuit will degrade the sound. You will get more than what you loss. When the phase is more corrected, you will find things sounding extreme precisely positioned and a lot better than the better two ways system
If you look up the phase difference with JX92S. You will find there is some 300 degrees apart between 20Hz and 20 kHz. So, I used RLC to correct the phase. It works very well with 0.5mH, 4ohm and 8-12 uF in parallel and the whole circuit in series the 92S. Enjoy the difference🙂. you will find to add an impedence correction circuit at the input of speaker to balance the impedence will improve the sound too.
I do not want to write too much for someone does not read. So e-mail to me at erictoucan@yahoo.co.uk. We can talk in more details.
Do not be afraid of correction circuit will degrade the sound. You will get more than what you loss. When the phase is more corrected, you will find things sounding extreme precisely positioned and a lot better than the better two ways system
Hi - That compensation circuit sounds interesting. I'll get some components and give it a go and report back.
BTW, don't be afraid to post here, rather than on email, as I'm sure there's a number of us interested in the details.
I've recently been experimenting with a JX53 linear array and am beginning to realise how freq compensation can modify the sound in the particular cabinet I've used (an Augsperger TL design which at present sounds too 'light').
Colin
BTW, don't be afraid to post here, rather than on email, as I'm sure there's a number of us interested in the details.
I've recently been experimenting with a JX53 linear array and am beginning to realise how freq compensation can modify the sound in the particular cabinet I've used (an Augsperger TL design which at present sounds too 'light').
Colin
- Status
- Not open for further replies.