Dear Experts,
I'm building a budget 2 way speaker and I would have your opinion on where I am and if my crossover design is correct. I've simulated and built the cabinet, vented box, braced, measured with the UMIK-1 at 1 mt
Drivers: Tymphany XT25TG30-04 with horn, SB SB20PFCR30-4
FR, in box at 1 mt, gated, not smoothed
woofer
tweeter
FR simulated with BoxSim
Crossover network
My questions
1. is the XO design correct, elegant, or can I make something better?
2. the impedance goes below 4 in some frequencies: I use a standard AV amplifier, do I need to correct them or not (I will use the speakers at loud volume)
3. the drivers are acoustically misaligned by 7mm: do I need to correct it?
4. Is the frequency response good, and how much I can trust BoxSim to buy expensive crossover parts?
Thanks to all for the inputs!!!
Cheers
I'm building a budget 2 way speaker and I would have your opinion on where I am and if my crossover design is correct. I've simulated and built the cabinet, vented box, braced, measured with the UMIK-1 at 1 mt
Drivers: Tymphany XT25TG30-04 with horn, SB SB20PFCR30-4
FR, in box at 1 mt, gated, not smoothed
woofer
tweeter
FR simulated with BoxSim
Crossover network
My questions
1. is the XO design correct, elegant, or can I make something better?
2. the impedance goes below 4 in some frequencies: I use a standard AV amplifier, do I need to correct them or not (I will use the speakers at loud volume)
3. the drivers are acoustically misaligned by 7mm: do I need to correct it?
4. Is the frequency response good, and how much I can trust BoxSim to buy expensive crossover parts?
Thanks to all for the inputs!!!
Cheers
I have found that measured phase can be different from derived phase. If possible, when you take gated measurements of the woofer and tweeter, try to capture phase.
To answer your questions
It is looking pretty good. More tweaking might get you a slightly flatter response, or maybe not. It is quite nice.
Most speakers which are called "4 Ohm" actually have impedance minimums in the 3 Ohm range. Most 2 channel amps can handle this kind of 4 Ohm speaker. I set a friend up with a very common Sony 40 W receiver (vintage 1988) to drive a 4 Ohm speaker, and he was happy for years. The only way to know for sure if your amp will handle it is to try it. But I think the risk is low.
I am not sure what kind of misalignment you are talking about. If it is horizontal alignment, the answer is No. If it is distance from the listener, the answer is more complicated.
Your boxsim simulation needs to take into account the difference in distance between the woofer and tweeter, and I can't tell from the FR plot if you have done so... I use Xsim, so I know nothing about boxsim. 7mm is not much considering your crossover frequency is 1500 Hz, so this may be nothing to worry about. Can you elaborate on the misalignment?
Assuming you have made good valid measurements, crossover simulations are pretty accurate.
However, final voicing is done by ear, and you will need some way of making small adjustments. Typically the tweeter level is what needs adjusting. You should buy some 1, 2, and 3 ohm resistors when you order your parts.
If you need to decrease the tweeter a little, you could add a little resistance on the amp side of the tweeter (in other words add the resistance so it is between the amp and the first tweeter capacitor). Amp side resistance doesn't change the filter characteristics very much.
If you need to raise up the tweeter a little, you could add some resistance to the parallel leg of the tweeter L pad... right now you have 1.5 ohm in series with the tweeter, and 4 ohm in parallel. Making that 4 ohm into 5 or 6 ohm willl raise up the tweeter level without changing the filter characteristics by much. You could also put a resistor in parallel with the 1.5 ohm... You will have to let your ears guide you along with measurements when you get to this stage.
To answer your questions
It is looking pretty good. More tweaking might get you a slightly flatter response, or maybe not. It is quite nice.
Most speakers which are called "4 Ohm" actually have impedance minimums in the 3 Ohm range. Most 2 channel amps can handle this kind of 4 Ohm speaker. I set a friend up with a very common Sony 40 W receiver (vintage 1988) to drive a 4 Ohm speaker, and he was happy for years. The only way to know for sure if your amp will handle it is to try it. But I think the risk is low.
I am not sure what kind of misalignment you are talking about. If it is horizontal alignment, the answer is No. If it is distance from the listener, the answer is more complicated.
Your boxsim simulation needs to take into account the difference in distance between the woofer and tweeter, and I can't tell from the FR plot if you have done so... I use Xsim, so I know nothing about boxsim. 7mm is not much considering your crossover frequency is 1500 Hz, so this may be nothing to worry about. Can you elaborate on the misalignment?
Assuming you have made good valid measurements, crossover simulations are pretty accurate.
However, final voicing is done by ear, and you will need some way of making small adjustments. Typically the tweeter level is what needs adjusting. You should buy some 1, 2, and 3 ohm resistors when you order your parts.
If you need to decrease the tweeter a little, you could add a little resistance on the amp side of the tweeter (in other words add the resistance so it is between the amp and the first tweeter capacitor). Amp side resistance doesn't change the filter characteristics very much.
If you need to raise up the tweeter a little, you could add some resistance to the parallel leg of the tweeter L pad... right now you have 1.5 ohm in series with the tweeter, and 4 ohm in parallel. Making that 4 ohm into 5 or 6 ohm willl raise up the tweeter level without changing the filter characteristics by much. You could also put a resistor in parallel with the 1.5 ohm... You will have to let your ears guide you along with measurements when you get to this stage.
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thanks!!
Yes, UMIK-1 for FR, measured with REW at 1mt outdoor with kind of far object reflection, Dayton V2 for the zma file, measured in box
gate value
Tweeter gated
Woofer gated
together gated
@Hifijim, thanks for the detailed answer!
I measured the time delay with reference loop with REW, on axis, at tweeter centre, and the difference was 7mm: I think that the right definition is "acoustic centre", but I'm not sure; I use it for see if the drivers are time aligned. It's accurate because I move the mic by 1cm and it was reflected in the measurement
I've attached the measurement and the technique that I used , I can share the REW files if you like to take a look
Thanks to all for the great feedback, really appreciate your comments and suggestions!
cheers
Dear Experts,
I need your kind review of the next steps in my project
Crossover layout
Could you please let me know if the components positions are correct and if I'm reducing the possibility of fire hazard (I read that the electrolytic may cause some time...)
Final FR
Final frequency response, with driver response. No smoothing, gated at 3.5ms
Polar response
Polar response, only vertical, I can't do horizontal
Do you think that I'm good to go? Any recommendation?
Thanks!
Cheers
I need your kind review of the next steps in my project
Crossover layout
Could you please let me know if the components positions are correct and if I'm reducing the possibility of fire hazard (I read that the electrolytic may cause some time...)
Final FR
Final frequency response, with driver response. No smoothing, gated at 3.5ms
Polar response
Polar response, only vertical, I can't do horizontal
Do you think that I'm good to go? Any recommendation?
Thanks!
Cheers
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