Hello,
I have bought a pair of homemade PA speakers and there is a problem that tweeters are too loud. I think that problem is there because 15" woofers are hi-fi and not PA, having only 90dB efficiency.
Woofers are FDC-HF15B
Crossover is SPF-8-2400 Pro and additional 0,15uF capacitor in series with tweeter (looks like previous owner wanted to solve the problem by raising crossover frequency...there is no point in that...😕)
And I don`t know about the tweeter, horn part is Sindax 195*155*114mm, but I can`t identify the driver, magnet is 120mm x 41mm, sticker has been removed.
Now back to the point, tweeters are so loud, if you stand 5m away from the speaker they are just yelling at you, your head hurts, it becomes listanable at 20m away from the speaker, but there are still too many highs, it sounds good at about 40m away. Were talking outside here. Yes, I could just position speakers 40m away, because I can, but I don`t want to sacrifice bass.
I am thinking of using L-pad configuration to solve this, but can anyone identify the tweeter? What wattage resistors should I use? If woofer has 90dB efficiency and tweeter has say for example 105db, should I attenuate tweeter for 15db?
Thank you for help!
I have bought a pair of homemade PA speakers and there is a problem that tweeters are too loud. I think that problem is there because 15" woofers are hi-fi and not PA, having only 90dB efficiency.
Woofers are FDC-HF15B
Crossover is SPF-8-2400 Pro and additional 0,15uF capacitor in series with tweeter (looks like previous owner wanted to solve the problem by raising crossover frequency...there is no point in that...😕)
And I don`t know about the tweeter, horn part is Sindax 195*155*114mm, but I can`t identify the driver, magnet is 120mm x 41mm, sticker has been removed.
Now back to the point, tweeters are so loud, if you stand 5m away from the speaker they are just yelling at you, your head hurts, it becomes listanable at 20m away from the speaker, but there are still too many highs, it sounds good at about 40m away. Were talking outside here. Yes, I could just position speakers 40m away, because I can, but I don`t want to sacrifice bass.
I am thinking of using L-pad configuration to solve this, but can anyone identify the tweeter? What wattage resistors should I use? If woofer has 90dB efficiency and tweeter has say for example 105db, should I attenuate tweeter for 15db?
Thank you for help!
Attachments
This is a compression horn, meant to go on the back of a horn.
You need both a high pass filter, and a pad. To design both you need to know the impedance curve as well as the frequency response. With luck maybe someone can figure out what you have and you can learn this from specs.
Best,
E
You need both a high pass filter, and a pad. To design both you need to know the impedance curve as well as the frequency response. With luck maybe someone can figure out what you have and you can learn this from specs.
Best,
E
Yes, I`m hoping that someone will be able to identify the tweeter. highpass filter is already there (the crossover is crossed at 2khz).
Thank you
All looks fairly clueless to me! 😀
The SPF 8 2400 must be wired up like the 2.5kHz eminence PXB2 2K5CX.
Looks like a 4 ohm filter to me! 7uF is large for a compression driver. But you do need considerable attenuation here, it seems. I wouldn't like to guess on polarity.
The SPF 8 2400 must be wired up like the 2.5kHz eminence PXB2 2K5CX.
Looks like a 4 ohm filter to me! 7uF is large for a compression driver. But you do need considerable attenuation here, it seems. I wouldn't like to guess on polarity.
Attachments
Found a similar looking driver on ebay
GMI sound D-59
60oz
1KHz to 18KHz
115dB 2.83V/1m
1000W
8ohm
1and3/8" x 18tpi thread
GMI sound D-59
60oz
1KHz to 18KHz
115dB 2.83V/1m
1000W
8ohm
1and3/8" x 18tpi thread
All looks fairly clueless to me! 😀
The SPF 8 2400 must be wired up like the 2.5kHz eminence PXB2 2K5CX.
Looks like a 4 ohm filter to me! 7uF is large for a compression driver. But you do need considerable attenuation here, it seems. I wouldn't like to guess on polarity.
Here is the schematic of the crossover, I don`t know the inductance of the coils... and the bulb is blown... had checked bulb in other speaker and its also blown, it`s hard to read it but I believe that it is 12v 20w bulb... Coil resistance of tweeter measured with multi meter is 6.4ohm...
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Without knowing much about what attenuation you need, I'd start with a 5.6R 10W ceramic series resistor and put 10W ceramic 5.6R shunt across the Compression driver.
That would put the load near 8 ohms. Then try smaller resitors across the tweeter if it needs taking down further. It then really shouldn't go lower than 6 ohms if you do this.
It's actually a bit weird that the tweeter is too loud if the fuse or glass bulb has blown. But I dont see why you couldn't just short the fuse out if you are careful with levels. Use a bit of 15A fuse wire, which is just tinned copper usually.
That would put the load near 8 ohms. Then try smaller resitors across the tweeter if it needs taking down further. It then really shouldn't go lower than 6 ohms if you do this.
It's actually a bit weird that the tweeter is too loud if the fuse or glass bulb has blown. But I dont see why you couldn't just short the fuse out if you are careful with levels. Use a bit of 15A fuse wire, which is just tinned copper usually.
Ok, I will contact the store for some resistors (everything bigger than 1/2w they have to order). "epicyclic" found tweeter that looks the same, I think that it could be the right one. That one has 115dB efficienc, would that mean that I would have to atteunate for -25dB because woofer is 90dB? I can leave fuse out right? I can`t imagine how loud tweeter would be without the fuse is it is way to loud now.
But there is just 10w 20ohm resistor across the fuse now. Should it be taken into account for attenuation?
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This could also be a solution, but it`s cheaper to buy few resistors, than another amplifier and easyer to carry it around...
I would be inclined to keep the 20 ohm resistor in place and replace the light bulb , all as a fail safe . Is the bulb a 12V 50W halogen . The resistors that " system 7 " suggested would all be additional components . A 12V 50W halogen in parallel with 20ohm will give approx. up to 2.4ohm of additional resistance .
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Yes, but unfortunately I can`t say for sure what is written on the bulb, it`s unclear and god knows how louder would tweeter get with bulb installed, I`m used to driving speakers to the limits without fuses, so it really doesn`t help me... I would like to leave the resistor as it is and no bulb and adopt l-pad to this resistor. If I understand correctly I would only need to add resistor across + and - because 20ohm resistor is already on the crossover in series with the tweeter, but this resistor is before the 7uF capacitor, I understand that it would be better to make L-pad after the capacitor (less power). so can I leave this resistor before the capacitor and connect resistor in parallel after the capacitor?
Ok, but what will happen with cut off frequency if I change it? Will it stay the same?
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