Back again.......!
Ok, so this afternoon I did some very quick and dirty open heart surgery on one speaker to test the suggestions. Here is what I did:
Add 1uf cap in Parallel with the existing 1uf cap at C2 (I thought this was close enough to 2.2uf for testing)
Added the 3.3uf cap across L4
Added an 8.2 ohm resistor in series with the tweeter to try and achieve 6db attenuation (I didn't have the resistors to do it with an L Pad)
The measured result is obviously better. I'm wondering if there are further tweaks to the caps or resistor values that may bring the upper-midrange back up a few db or further attenuate the response from 4kHz onwards?
It has had an obvious effect on the woofer response, not sure what's going on there?
Ok, so this afternoon I did some very quick and dirty open heart surgery on one speaker to test the suggestions. Here is what I did:
Add 1uf cap in Parallel with the existing 1uf cap at C2 (I thought this was close enough to 2.2uf for testing)
Added the 3.3uf cap across L4
Added an 8.2 ohm resistor in series with the tweeter to try and achieve 6db attenuation (I didn't have the resistors to do it with an L Pad)
The measured result is obviously better. I'm wondering if there are further tweaks to the caps or resistor values that may bring the upper-midrange back up a few db or further attenuate the response from 4kHz onwards?
It has had an obvious effect on the woofer response, not sure what's going on there?
Hi there ...
For some reason I can't open your attachment, but I can see the Green & Red frequency plots.
Would I be right assuming that Green is before your mods. and Red is after?
The below 200Hz results would surly be room modes/reflections/mic position type things, and should probably be ignored.
At this point, if your ears pretty much like the sound, without C/O complexity, you may have a speaker, like so many that has its own 'sound signature'.
There are only two more simple things I can suggest > reverse the polarity of the tweeter just to see how that measures.
To 'pick-up' sparkle above 10Khz, you can try adding a .68 or1uF capacitor in parallel with tweeter resistor you have added 🙂
For some reason I can't open your attachment, but I can see the Green & Red frequency plots.
Would I be right assuming that Green is before your mods. and Red is after?
The below 200Hz results would surly be room modes/reflections/mic position type things, and should probably be ignored.
At this point, if your ears pretty much like the sound, without C/O complexity, you may have a speaker, like so many that has its own 'sound signature'.
There are only two more simple things I can suggest > reverse the polarity of the tweeter just to see how that measures.
To 'pick-up' sparkle above 10Khz, you can try adding a .68 or1uF capacitor in parallel with tweeter resistor you have added 🙂
Thanks.
You are correct regards the response colours.
I’ll play around with the driver polarity and I'm pretty sure I've a few more 1uf caps round to piggyback the resistor, but I have just order a bunch of 10w wire wound resistors (2.7, 3.3, 4.7, 6.8, 8.2, 10 & 15 ohm) to be delivered tomorrow so that I can properly play around with the tweeter L Pad, rather than a single resistor.
I’ll also need to re-measure both speakers as I don’t believe the difference in response is all caused by the room. When I have previously measured both speakers individually they did not have entirely differing responses like that....... The 34hz peak is definitely the room but the rest of the response up to 600hz is completely different and the early roll-off seems odd. The speakers original response is supposed to be down to 38hz. However, I'm probably doing too much at once to be able properly monitor what tweaks are having what affect.
The parallel cap on C2 and the cap across L4 seem to have done a good job of smoothing out the upper response so I'll get them soldered in to place and re-measure before I mess around with the L Pad.
👍👍
You are correct regards the response colours.
I’ll play around with the driver polarity and I'm pretty sure I've a few more 1uf caps round to piggyback the resistor, but I have just order a bunch of 10w wire wound resistors (2.7, 3.3, 4.7, 6.8, 8.2, 10 & 15 ohm) to be delivered tomorrow so that I can properly play around with the tweeter L Pad, rather than a single resistor.
I’ll also need to re-measure both speakers as I don’t believe the difference in response is all caused by the room. When I have previously measured both speakers individually they did not have entirely differing responses like that....... The 34hz peak is definitely the room but the rest of the response up to 600hz is completely different and the early roll-off seems odd. The speakers original response is supposed to be down to 38hz. However, I'm probably doing too much at once to be able properly monitor what tweaks are having what affect.
The parallel cap on C2 and the cap across L4 seem to have done a good job of smoothing out the upper response so I'll get them soldered in to place and re-measure before I mess around with the L Pad.
👍👍
Also……. you’ll be fed up of me soon…. 😂
I’ve just took another look at the 4ohm tweeters I’ve got here, they are Vifa BC25SC15-04, date sheet attached.
Any advice or guidance on how best to implement an L Pad to use these with the existing 8 ohm mid and woofer??.
Thanks.
I’ve just took another look at the 4ohm tweeters I’ve got here, they are Vifa BC25SC15-04, date sheet attached.
Any advice or guidance on how best to implement an L Pad to use these with the existing 8 ohm mid and woofer??.
Thanks.
The crossover schematic you supplied in post #33 indicates an 8 ohm tweeter in the high pass filter section.
If the modeling that has already been done was for an 8 ohm tweeter, then I would expect new modeling to be required if it's actually a 4 ohm tweeter.
The L-pad implementation is not affected other than to enter 4 ohm into the L pad calculator that I gave you instead of 8 ohm.
If the modeling that has already been done was for an 8 ohm tweeter, then I would expect new modeling to be required if it's actually a 4 ohm tweeter.
The L-pad implementation is not affected other than to enter 4 ohm into the L pad calculator that I gave you instead of 8 ohm.
To convert an 8 ohm crossover to 4 ohm. Halve your resistances and inductances, but double the capacitances.
This is if all else is equal.
This is if all else is equal.
If you use these tweeters 🙂 I'm not sure that you really need to use an L-pad. Simply adding a 4.7ohm resistor in series will not only provide attenuation,
but also create a basic 8ohm load for the crossover.
PS.
The modifications made so far really can't be responsible for the low frequency issues you have noted. Is the speaker box sealed or ported ?
Phew….. I had a marathon today…. The resistors arrived so I knocked up the L Pads and installed them with the original tweeters. I spent a good hour two measuring every-which way, switched polarity etc. in the end I decided that it sounded (measured) best with both the tweeter and midrange in reverse polarity. I still need to play around a little with position, toe-in and the subwoofer but here is where I got to with a little EQ applied below 1khz:
