Just for those who are interested:
I did a groundplane measurement of my speaker. Here is the result:
I have still the impression that the mids are a bit suppressed and the upper mids to bright. ( you can see it in the graph)
But I shall and will improve the frequency response of this monitor. Even if I must design a complete new crossover. I think that a higher order crossover for the woofer will solve this problem. I go for it...
I did a groundplane measurement of my speaker. Here is the result:
I have still the impression that the mids are a bit suppressed and the upper mids to bright. ( you can see it in the graph)
But I shall and will improve the frequency response of this monitor. Even if I must design a complete new crossover. I think that a higher order crossover for the woofer will solve this problem. I go for it...
Attachments
There are several thing you can try very easy
1. Resistor on 0.2mH tweeter coil
2. Bigger resistor R1 on 12uF woofer
3. Try add additional RC on woofer (smaller values)
4. Woofer coil 3mH seems somewhat big, maybe
5. MAYBE, remove tweeter 20uF
6. 8ohm on tweeter seems a lot
Dont settle on one resistor, but try several values and remember it all interacts with each other
POLARITY - hard to say with this - have you tried to change polarity on tweeter
1. Resistor on 0.2mH tweeter coil
2. Bigger resistor R1 on 12uF woofer
3. Try add additional RC on woofer (smaller values)
4. Woofer coil 3mH seems somewhat big, maybe
5. MAYBE, remove tweeter 20uF
6. 8ohm on tweeter seems a lot
Dont settle on one resistor, but try several values and remember it all interacts with each other
POLARITY - hard to say with this - have you tried to change polarity on tweeter
The resistor before the tweeter was changed from 8 to 5 ohm, to correct the level of the tweeter. (I fogot to mention)
I've also tried to lower the inductance of the 3mH coil in the woofer crossover but then the 890 Hz frequenty range is to high.
I did also a test when the resistor in the woofer crossover was 0 ohm. This helps a little let say not more then 0.5 dB at 1Khz.
I'm going to measure the freuency and impedance reponse without crossover and import this in speaker workshop. Then I'm going to test everything what was mentioned before and simulate it on the computer.
When everythings looks nice on the computer I'll put it here on the forum so that everyone can put comments.
Then I'll make the changes, test the speakers and do also a test with inverse tweeter polarisation to see there will be a large dip.
I've also tried to lower the inductance of the 3mH coil in the woofer crossover but then the 890 Hz frequenty range is to high.
I did also a test when the resistor in the woofer crossover was 0 ohm. This helps a little let say not more then 0.5 dB at 1Khz.
I'm going to measure the freuency and impedance reponse without crossover and import this in speaker workshop. Then I'm going to test everything what was mentioned before and simulate it on the computer.
When everythings looks nice on the computer I'll put it here on the forum so that everyone can put comments.
Then I'll make the changes, test the speakers and do also a test with inverse tweeter polarisation to see there will be a large dip.
Hello, Jonasa,
several years ago I built a speaker with similar drivers but in a ported box.
The design was from the "Speaker Builders Loudspeaker Projects #1" book, an American publication by Edward Dell.
The project was titled "Reference Monitor" and used Scanspeak drivers, the D2905/9900 (Revelator) or D2905/9700 tweeters and the black coated 18W8546/01 woofer.
I used the revelator and the 18W8546 which is the same Kevlar driver without the black coating. It was my understanding that this speaker was designed by Scanspeak themselves.
The port consisted of a 2 inch piece of PVC ~ 6 inches long that was stuffed with straws.
While I still have them and use them rarely because I prefer single driver speakers at the moment (my likes / dislikes tend to be cyclic in nature), I can without any hesitation say that these speakers are excellent by any measure.
Since they use the same drivers perhaps you may be interested in buiilding a pair of the ported boxes to compare.
here.plans here
good luck.
several years ago I built a speaker with similar drivers but in a ported box.
The design was from the "Speaker Builders Loudspeaker Projects #1" book, an American publication by Edward Dell.
The project was titled "Reference Monitor" and used Scanspeak drivers, the D2905/9900 (Revelator) or D2905/9700 tweeters and the black coated 18W8546/01 woofer.
I used the revelator and the 18W8546 which is the same Kevlar driver without the black coating. It was my understanding that this speaker was designed by Scanspeak themselves.
The port consisted of a 2 inch piece of PVC ~ 6 inches long that was stuffed with straws.
While I still have them and use them rarely because I prefer single driver speakers at the moment (my likes / dislikes tend to be cyclic in nature), I can without any hesitation say that these speakers are excellent by any measure.
Since they use the same drivers perhaps you may be interested in buiilding a pair of the ported boxes to compare.
here.plans here
good luck.
Rho:
I'll do the measurement at the end of the comming week. Tomorrow it's is working day for me and I must go to a foreign country this week.....
I'll post measurement with and without crossover from the separate drivers mounted in the box. frequency and impedance.
Do I need additional measurement..?
Andrewbee:
Thanks for posting. At this moment I won't start building a new box or encloser. I'm completely convinced that I'll get my current box right.
It must be possible with the help of the people from this webside to build a crossover for this small studio monitor so that the frequency is flat from 70Hz to 10Khz within a range of +/- 1 and a half dB 
I'll do the measurement at the end of the comming week. Tomorrow it's is working day for me and I must go to a foreign country this week.....
I'll post measurement with and without crossover from the separate drivers mounted in the box. frequency and impedance.
Do I need additional measurement..?
Andrewbee:
Thanks for posting. At this moment I won't start building a new box or encloser. I'm completely convinced that I'll get my current box right.
It must be possible with the help of the people from this webside to build a crossover for this small studio monitor so that the frequency is flat from 70Hz to 10Khz within a range of +/- 1 and a half dB
Try the 'Scanspeak Reference Monitor' crossover as suggested by a member in this thread with cheap crossover materials, measure and evaluate.
I am sorry to say (bcs you have already spent in excellent crossover components) that I have never heard a V.D. design sounding right at all.
The shift in FR when you move your mic is normal bcs of changes in cancellation paths and bsc proximity. Better measure @ 2m and on tweeter axis, not middle of box.
I am sorry to say (bcs you have already spent in excellent crossover components) that I have never heard a V.D. design sounding right at all.
The shift in FR when you move your mic is normal bcs of changes in cancellation paths and bsc proximity. Better measure @ 2m and on tweeter axis, not middle of box.
Jonasa,
The SS 18W8545 you seem to be using in a volume of 8 liters needs about twice volume to play bass well in both ported and closed box. This is why your bass response is so poor. The Dickason's project calls for 18W8545K. You need to either change the driver or build new cabinets.
Misha
The SS 18W8545 you seem to be using in a volume of 8 liters needs about twice volume to play bass well in both ported and closed box. This is why your bass response is so poor. The Dickason's project calls for 18W8545K. You need to either change the driver or build new cabinets.
Misha
Misa A. and others:
Sorry, I'm terribly sorry I made a type mistake and didn't wrote the full name of the woofer.
But I'm realy using the 18w8545K.
Al the measurements are taken with the 18w8545K woofer .
The only difference with the studio monitor from Vance is that I've changed the resistor in the tweeter XO from 8 to 5 ohm to make SPL right.
Sorry, I'm terribly sorry I made a type mistake and didn't wrote the full name of the woofer.
But I'm realy using the 18w8545K.
Al the measurements are taken with the 18w8545K woofer .
The only difference with the studio monitor from Vance is that I've changed the resistor in the tweeter XO from 8 to 5 ohm to make SPL right.
Hi everybody,
After more then half a year I will continue this thread.
I've worked more then half a year to improve the crossover. The result is very spectacular.
With the crossover from Vance the frequency response has large bumps +/- 2.5dB in the midrange. Also the phase is very poor.
I've my new design of the crossover ready on paper and it looks very spectacular. The frequency respons is +/-1 dB exept one small peak from baffle (reflection agains speaker frontpanel) and the peak above 10Khz but this is normal for the tweeter.
Also the phase of my new crossover is very spectacular. I've a deep null with reversed polarity more then 40dB. With the original studio monitor from Vance I measured less then 20dB.
I've learned speaker workshop and I did a lot of measurements.
Then I've learned LspCad that I've used for my complete new crossover design.
I'll post everything on this thread in the comming days. I hope I will get a lot of new inputs from all of you.
The new crossover will not be cheap. But I want to improve my monitor at no price. It looks more then spectacular on paper.
I'hope I can build the new crossover soon.
After more then half a year I will continue this thread.
I've worked more then half a year to improve the crossover. The result is very spectacular.
With the crossover from Vance the frequency response has large bumps +/- 2.5dB in the midrange. Also the phase is very poor.
I've my new design of the crossover ready on paper and it looks very spectacular. The frequency respons is +/-1 dB exept one small peak from baffle (reflection agains speaker frontpanel) and the peak above 10Khz but this is normal for the tweeter.
Also the phase of my new crossover is very spectacular. I've a deep null with reversed polarity more then 40dB. With the original studio monitor from Vance I measured less then 20dB.
I've learned speaker workshop and I did a lot of measurements.
Then I've learned LspCad that I've used for my complete new crossover design.
I'll post everything on this thread in the comming days. I hope I will get a lot of new inputs from all of you.
The new crossover will not be cheap. But I want to improve my monitor at no price. It looks more then spectacular on paper.
I'hope I can build the new crossover soon.
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