Hi,
I have below the above cross over which is a 3rd order.
The original cap was electrolytic.I have replace all the cap with Jantzen Crosscap and resistors to Kiwame. What I found is better clarity but the bass is lacking.
1. Should I follow the capacacitor printed in the label or based on measurement. I actually measure 11.9uF on the electrolytic on one of them and the other 11.5uF? Which one to follow ??
2. I change R2 from 1R5 to 1R8, and I get better bass response. However I found the sound slightly compress, not so open. Why ?
3. What software do I use to simulate if the crossover is still at 3kHz.
I have below the above cross over which is a 3rd order.
The original cap was electrolytic.I have replace all the cap with Jantzen Crosscap and resistors to Kiwame. What I found is better clarity but the bass is lacking.
1. Should I follow the capacacitor printed in the label or based on measurement. I actually measure 11.9uF on the electrolytic on one of them and the other 11.5uF? Which one to follow ??
2. I change R2 from 1R5 to 1R8, and I get better bass response. However I found the sound slightly compress, not so open. Why ?
3. What software do I use to simulate if the crossover is still at 3kHz.
Re: the caps, I'd go with what's on the label; electros change value over time.
I'd leave R2 as it is (I think it's there to change the Q of the driver) - increasing it will waste power. I'd increase R1 instead to get the balance you want.
If you have measured the actual impedance of the drivers at 3 KHz, you can plug the numbers into the calculator here:
http://ccs.exl.info/calc_cr.html#second
I'd leave R2 as it is (I think it's there to change the Q of the driver) - increasing it will waste power. I'd increase R1 instead to get the balance you want.
If you have measured the actual impedance of the drivers at 3 KHz, you can plug the numbers into the calculator here:
http://ccs.exl.info/calc_cr.html#second
Below is the spec of the speaker : -
Design 2 way bookshelf
Drive units HF: 25 mm (1”) silk dome tweeter
LF: 130 mm (5.25”) pp coated cone
Frequency response at ±3 dB 52 Hz - 20 kHz
Crossover frequency 3 kHz
Amplifier requirements 10 - 100W
Sensitivity (2.83V/1m) 90 dB
[bold]Impedance 8 Ohms [/bold]
Maximum output 108 dB
Can I assume 8 ohms is the impedance at 3khz. or do I ulsolder the wire and measure the resistance.
I plug in the figure and it seems a little different. Is it due to the speaker driver acutal response.
Design 2 way bookshelf
Drive units HF: 25 mm (1”) silk dome tweeter
LF: 130 mm (5.25”) pp coated cone
Frequency response at ±3 dB 52 Hz - 20 kHz
Crossover frequency 3 kHz
Amplifier requirements 10 - 100W
Sensitivity (2.83V/1m) 90 dB
[bold]Impedance 8 Ohms [/bold]
Maximum output 108 dB
Can I assume 8 ohms is the impedance at 3khz. or do I ulsolder the wire and measure the resistance.
I plug in the figure and it seems a little different. Is it due to the speaker driver acutal response.
Re: "Can I assume 8 ohms is the impedance at 3khz. or do I ulsolder the wire and measure the resistance."
No and No.
What you need to measure is the ac impedance at 3KHz.
This can be done with a signal generator and an AC voltmeter, but the easy way nowadays is to make a simple jig and download ARTA software, and use you computer to do the measurement.
ARTA http://www.fesb.hr/~mateljan/arta/download.htm
ARTA Jig - http://zobsky.blogspot.com/2008/01/simple-loudspeaker-measurement-jig-for.html
No and No.
What you need to measure is the ac impedance at 3KHz.
This can be done with a signal generator and an AC voltmeter, but the easy way nowadays is to make a simple jig and download ARTA software, and use you computer to do the measurement.
ARTA http://www.fesb.hr/~mateljan/arta/download.htm
ARTA Jig - http://zobsky.blogspot.com/2008/01/simple-loudspeaker-measurement-jig-for.html
PeteMcK said:
I would do the opposite and test. Maybe also testing it with less R2 (or without it, if not changing a lot of things like xover freq) and adjusting R1. If you have to leave R2 as it is (R2=1.5) make sure you use adequate power (W) or 4 resistors in series/parallel (for the same/similar speaker power).
ccschua said:
1) The difference from 11.5 to 11.9 and finally to -12- shouldn't affect Your pleasure.
2) Very sensible to really hear a difference. With the bigger R You attentuate the lower mids more related to bass and treble.
3) You wouldn't gain insight from that. The simulation would lack original data on speakers impedance and amplitude and phase in the peticular cabinet.
Nice speaker though. Best You leave it as it is. If You HAD to change the caps because they MEASURED bad You probably should add resistors ~ 0.5 .. 2Ohm to make more modern caps appear as electrolytics.
have fun
Inductor said:
I tested R2 using 1R3 and the bass response is reduced. I also increase R2 to 2R3 but found the bass to be boomy.
Re: Re: KEF Cresta 10 Crossover
I mean C2 was 10uF but when I measure I got 11.5uF and 11.9uF for left/right channel.
I felt this way too. But when I listen to PEPE Romero flamenco, the feet thumping effect is less if I reduced R2.
I mean C2 was 10uF but when I measure I got 11.5uF and 11.9uF for left/right channel.
I felt this way too. But when I listen to PEPE Romero flamenco, the feet thumping effect is less if I reduced R2.
The original R1 and R2 were using ceramic resistor. First I change the high pass R1 from original Ceramic resistor to Kiwame 2R7. Not much differerence here, although I was told it is supposed to be smoother.
Then I changed driver resistor R2 to Mills MRA 1R5 (for trial) but found the bass lacking.
Is Mills resistor fit for crossover ? what do you recommend the resistor type.
Next I will do is replace R1 with say 3R to see if the bass is more prominent while Maintain 1R5.
Then I changed driver resistor R2 to Mills MRA 1R5 (for trial) but found the bass lacking.
Is Mills resistor fit for crossover ? what do you recommend the resistor type.
Next I will do is replace R1 with say 3R to see if the bass is more prominent while Maintain 1R5.
ccschua said:
What's the power for this resistor (R2-5/10W?)
Do you know if the original ceramic resistor (R2) had any inductance that this one you are using lacks. (Now I am more confused. Maybe not because there's a lot of things going on now.) You are saying that what ever you do to R2 you always end losing bass.
Re: Re: Re: KEF Cresta 10 Crossover
If you change R2 to 1.8R you get LESS bass and YES more compressed sound (in the mids). Tops (low and high) get higher at around 80Hz and 2KHz or whatever.ccschua said:
Again, what resistor are you using(?). You can have either, that you think is more transparent (in this case only R2 for main driver). Make sure power is enough (10W or more depending as much as you use with your ampli). So now I would go with 1R3 or 1R5 or stay with the one you like if 1R8. Mills is very good for tweeters.ccschua said:
...This should answer your question, for now, to start with. (1.st part) If you change resistor for a very high setting like 1R8 you are messing with the overall system, but we can look from there.Inductor said:
The original resistor used (both R1 and R2 ) are 5W and 5%.
What I will do is replace back R2 with 1.5R 5W Mills MRA and then try R1 with 3R 5W. Will report what I hear.
What I will do is replace back R2 with 1.5R 5W Mills MRA and then try R1 with 3R 5W. Will report what I hear.
Re: Re: Re: KEF Cresta 10 Crossover
Jantzen Crosscap should work fine, make it low value like 10uF. The sound across the xover region comes more round for better integration with tweeter with this. Like others already said, it's not changing a lot but bigger the value and then the high notes (2KHz) get stonger/peaking. (2.nd part) Later you can get better caps for the tweeter, 4 now they are just fine.
ccschua said:
ccschua said:
Jantzen Crosscap should work fine, make it low value like 10uF. The sound across the xover region comes more round for better integration with tweeter with this. Like others already said, it's not changing a lot but bigger the value and then the high notes (2KHz) get stonger/peaking. (2.nd part) Later you can get better caps for the tweeter, 4 now they are just fine.
ccschua said:
Good, you are all over the map... what cap C1 do you have now, is it a new 10uF Jantzen Crosscap (and 6uF/C2 - 7uF/C3)?
ccschua said:
It will smooth the tweeter about ~0.5 dB, what might work good, giving you a strong midbass line. I would use MOX-10W resistors, factories never do it right (5W) the "first time" with the final product. Kudos for PeteMcK, for what was said before, and for wxa666 of course. (ccschua) You are increasing "heat" inside the speaker anyway, in this case w a good intention. 😴
Did you test with some foam around the tweeter like in the originals BBCs for "padding" and less reflections(?).
Inductor said:
C1 is 10uF Jantzen crosscap
C2 is 2.7+3.3 Jantzen cross cap
C3 is 6.8uF crosscap.
I think I may need a bigger C3 (as the simulation shows )
ccschua said:
The 6.8uF (C3) is perfect on paper with the new R1. A cap of 6uF would be similar of what you had, before changing R1 to 3R. To compare, a 8uF would give you a more round sound on tweeter at xover band (higher) and more relaxed for high frequencies. To adjust level (+/-) go back to R1.
Fig.: KEF CRESTA 10 xover electric
R1=3R0
C2=6uF
C3=6.8uF
L3=0.21mF/0.50R
Attachments
A.
Today I switch R2 from 1R8 to 1R5. What I notice the clarity and separation is better.
B.
Then I switch R1 from 2R7 (Kiwame) to 3R3 (Ceramic resistor, 7W). What I hear is that the treble is less, bass is still the same as above.
Between A and B, I would choose A but probably with the resistor value around 3R.
Can you help me out with the new cross over frequency with the new R2 = 3R3.
tks
Today I switch R2 from 1R8 to 1R5. What I notice the clarity and separation is better.
B.
Then I switch R1 from 2R7 (Kiwame) to 3R3 (Ceramic resistor, 7W). What I hear is that the treble is less, bass is still the same as above.
Between A and B, I would choose A but probably with the resistor value around 3R.
Can you help me out with the new cross over frequency with the new R2 = 3R3.
tks
ccschua said:
Make sure your tweeter resistor is of the type NI (non inductive) when using a ceramic with windings. With the 3R3 on R1 it will reduce about 0.5dB tweeter level.
Is not 90 dB anymore.
ccschua said:
I would go with my original statement of using a lower R2 as was said, for a test, and then adjusting from there.
Fig.: KEF CRESTA 10 xover electric
L1=1.15mF/0.55R, L2=0.20mF/0.30R, C1=10uF, R2=1R5,
R1=3R3
C2=6uF
C3=6.8uF
L3=0.21mF/0.50R
Attachments
The curve does not have much difference.
So I guess it must be my amp that has serious lacking in bass response. I have just upgrade my tube amp coupling cap to Mundorf supreme. I wonder the supreme take long burn in time. At the moment, the supreme has clocked 300 hours.
So I guess it must be my amp that has serious lacking in bass response. I have just upgrade my tube amp coupling cap to Mundorf supreme. I wonder the supreme take long burn in time. At the moment, the supreme has clocked 300 hours.
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