I just got a pair of CSS FR125s drivers. I want to put them in a sealed cabinet. I was planning on using the recommended design but if I'm going with a sealed speaker shouldn't the internal volume be smaller?
type,
Have you checked out the Planet_10 website?
There is a nice chart that gives 5 differnt sized boxes, the expected Q of the the system and the expected frequency responses for each.
http://www.planet10-hifi.com/
Look in the Box Plan Library.
R/
Jim
Have you checked out the Planet_10 website?
There is a nice chart that gives 5 differnt sized boxes, the expected Q of the the system and the expected frequency responses for each.
http://www.planet10-hifi.com/
Look in the Box Plan Library.
R/
Jim
I have them now in a ~5 liter sealed and still feel they're a bit boomy and undetailed. Probably no longer a problem with box, but the driver.
Landroval said:
The boom's the box, 5 liter is too small, so you get boomy bass. The lack of detail could be the driver, it slightly rolls off above 10kHz - I find it smooth others undetailed.
best, LC
Yes, I agree a bit. The 8 liter vented (or aperiodic) is a bit better, but I don't like the sound of the driver that much. It leaves so much stuff out (not only from the top octave).
Theres a hole in the response between 8k and 11k which I filled in by using a graphic equaliser type circuit, which I could post if anyones interested. The treble seems to improve with running in.
I wonder if the boom is caused by air leaking past the phase plug. Since there is no dust cap there is no air seal. Perhaps OB is the best for this driver.
I wonder if the boom is caused by air leaking past the phase plug. Since there is no dust cap there is no air seal. Perhaps OB is the best for this driver.
Yes, I'm interested in the circuit. I can confirm the dip at 9.6Hz, the problem compounded by the peak at 6.5Khz which effectively shows a 9db drop over that 3kHz bandwidth.consort_ee_um said:
I'm trying to decide on some parallel notch filter values for the 9.6kHz peak and also to flatten out the 700-2k region. The two notches should bring it down to +/- 3db from 60Hz-20kHz or better.
Here is the circuit. Its basically a graphic equaliser circut with a Higher Q than normal. IC1B, R4, R5 and C1 are a simulated inductor or gyrator circuit, and R1,R2 would be the pot in a graohic equaliser. C2 is a 470pF in parallel with a 39pF
I tried other bandpass circuits but they did horrendous things with the phase. With this you can change the centre frequency easily with C2 and the gain peak with R2.
I had to move the frequency up from the centre of the trough so that the filter skirt did not amplify the 7kHz peak, but I ended up with a surprisingly flat response and the phase was linear as well.
You can have more filters by connecting another R1-2,R4-5,C1-2 and IC1B across points A and B and if you make R1 small and R2 big you will get a notch.
I tried other bandpass circuits but they did horrendous things with the phase. With this you can change the centre frequency easily with C2 and the gain peak with R2.
I had to move the frequency up from the centre of the trough so that the filter skirt did not amplify the 7kHz peak, but I ended up with a surprisingly flat response and the phase was linear as well.
You can have more filters by connecting another R1-2,R4-5,C1-2 and IC1B across points A and B and if you make R1 small and R2 big you will get a notch.
Attachments
In general it is better to flatten the peaks rather than fill in the troughs, although purists might want to do both, so here is the notch filter -
To make a 5dB notch centred on 6.5kHz make C1 2.2nF C2 820pF R1 5.6k and R2 47k
Since the self powered op-amp is not yet with us (I claim the patent BTW) I admit I forgot the power supplies to the op-amps say +/- 12 or 15V
To make a 5dB notch centred on 6.5kHz make C1 2.2nF C2 820pF R1 5.6k and R2 47k
Since the self powered op-amp is not yet with us (I claim the patent BTW) I admit I forgot the power supplies to the op-amps say +/- 12 or 15V
@type & @Landroval:
You are right, 5 liters will be boomy. On the other side 10+ liters is already quite big for a nice bookshelf speaker.
In order to keep it small I experimented with a highpass-capacitor to keep the bass response on a linear level.
The result is a speaker called "Cyburgs-Monitor" (uuuh.... smart name) with 6,5 liters and a quite linear bass response down to about 50 Hz.
A notch filter is added make the mids more linear.
Have a look here, this thread is unfortunately in German, if anyone is interested I will make an English translation. In the first post you will see pictures, then a plan and the frequency response.
Cyburgs monitor in hifi-forum.de
nice greetings, Berndt
You are right, 5 liters will be boomy. On the other side 10+ liters is already quite big for a nice bookshelf speaker.
In order to keep it small I experimented with a highpass-capacitor to keep the bass response on a linear level.
The result is a speaker called "Cyburgs-Monitor" (uuuh.... smart name) with 6,5 liters and a quite linear bass response down to about 50 Hz.
An externally hosted image should be here but it was not working when we last tested it.
A notch filter is added make the mids more linear.
Have a look here, this thread is unfortunately in German, if anyone is interested I will make an English translation. In the first post you will see pictures, then a plan and the frequency response.
Cyburgs monitor in hifi-forum.de
nice greetings, Berndt
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