Hello, I have two Cerwin Vega 124s. They are 12", Single Voice Coil 4 ohm woofers. I have them running in series to a Kenwood PS300t amplifier. The amplifier supposedly runs 100w x 2 (RMS @ 4ohms) or 400w Bridged (RMS @ 4ohms). These ratings are at 14.4 volts which is from what I've been told what my car is pushing (2003 Acura TL-S). Otherwise the figures are reduced to 75X2 and 300 X 1 respecitively. The amp is not stable, bridged at 2ohms.
Here are my questions:
1) Which power figures is my car putting out, 14.4 V. or 12 V? and is there an easy way of determining this?
2) Is my current wiring of the two subs in series at 8 ohms using the bridged connection, giving me more power to each sub then I would get if they each had a channel and were run in stereo at 4 ohms? In general which is preferrable.
3) Also, I have noticed that the speakers do not necessarily move in perfect sink with each other if you watch the excursion of the woofers. Is this normal, or a sign of some kinda problem or distortion?
Thanks in advance for your input.
Replies (3)
cplkittle on 11/17/2003 06:55:04
a volt meter or ohm meter as they are sometimes called will be able to tell you the voltage, they are inexpensive and you can get them at radioshack. I have just learned here that matching the ohms of a speaker to the sub is the most efficient way of connecting them, going over or under in impedance could damage either your amp or your subs. Check the wiring on your subs, if they are out of sync, you probably have one wired in reverse (180 degrees out of phase) this will cancel out your sound. reversing hte polarity on either of your subs will quickly tell you if you have done this as it will sound alot louder and more powerful.
Swez on 11/17/2003 07:59:03
For the amp/sub combo, you have the best connection for max power. The other option is wiring one sub to each channel and run the amp as a 2 channel system. Same power as bridged. (~80 - 100 watts/sub)
As for car voltage, can measure the voltage at the amp input power lugs. When you car starts up, it will probably put out close to 14.0 volts. As the charging system catches up, a normal voltage reading will be more like 13.5 volts DC. When you turn on lights, heater and other devices, the output voltage may drop below 13.0 volts. This is normal in most cars.
Swez
PS If you want more sub power, a better amp would really improve your bass performance. In fact, this amp may sound better bridged with only 1 sub connected... assuming your box is sealed and each sub has its own sealed chamber. Try it!
eldevioso on 11/18/2003 13:55:08
Thanks a lot. Here's a little additional information that may have helped.
As far as the subs being out of sync: I'm almost positive they're wired correctly and it's not so much out of sync but less excursion on one speaker so it appears to be out of sync. But nevertheless I'll double check the wiring. Another factor is that one sub is years old and the other is brand new and there is an appropriate difference in "stiffness" of the speaker. Could this be what's causing the problem...It appears to be simply a visual problem, not a sound problem.
Swez: thanks for the input. I actually had a single sub running off the amp bridged, and it did sound close to what it sounds like now, which I assume is because it was getting much more power. However, these subs handle 400wRMS and from what I hear, Cerwin Vega subs really "like" power to perform well. Oh well, I think my problem is that I need a much bigger amp, I just wasn't planning on running dual 12s when I first put it all together. I guess the bug just caught me and I couldn't stop myself :)
As for my boxes, I built two custom tubes. They're built to spec at 2.22 cu ft of airspace and are air tight, aside from the huge 4" diameter 10.75' long port in the back of each one. The tubes are I think 14" diameter by just about 26" long, and I decided to go with only 1/2" wood pieces for the ends as the "tube" design minimizes forces on the wood walls. Further, the end piece that does receive the pressure of the woofer is 14" diameter circle and is 1/2" thick. I don't think it can flex at all. I chose ported enclosure because Vega doesn't provide sealed dimensions for these subs saying that they're designed for bassreflex vented enclosures. This introduces another question I had.
I was forced by design to place the port of the tube directly in the back of the speaker (i.e. at the opposite end of the tube, the back compared to the face of the tube). what are your opinions on the effectiveness of the port in this location, despite the fact there is no alternative with this design. From an untechnical point of view, I will say that It seems to hit appropriately and the sound is rich until i get high in the volume and my "overworked" amp starts distorting?
Here are my questions:
1) Which power figures is my car putting out, 14.4 V. or 12 V? and is there an easy way of determining this?
2) Is my current wiring of the two subs in series at 8 ohms using the bridged connection, giving me more power to each sub then I would get if they each had a channel and were run in stereo at 4 ohms? In general which is preferrable.
3) Also, I have noticed that the speakers do not necessarily move in perfect sink with each other if you watch the excursion of the woofers. Is this normal, or a sign of some kinda problem or distortion?
Thanks in advance for your input.
Replies (3)
cplkittle on 11/17/2003 06:55:04
a volt meter or ohm meter as they are sometimes called will be able to tell you the voltage, they are inexpensive and you can get them at radioshack. I have just learned here that matching the ohms of a speaker to the sub is the most efficient way of connecting them, going over or under in impedance could damage either your amp or your subs. Check the wiring on your subs, if they are out of sync, you probably have one wired in reverse (180 degrees out of phase) this will cancel out your sound. reversing hte polarity on either of your subs will quickly tell you if you have done this as it will sound alot louder and more powerful.
Swez on 11/17/2003 07:59:03
For the amp/sub combo, you have the best connection for max power. The other option is wiring one sub to each channel and run the amp as a 2 channel system. Same power as bridged. (~80 - 100 watts/sub)
As for car voltage, can measure the voltage at the amp input power lugs. When you car starts up, it will probably put out close to 14.0 volts. As the charging system catches up, a normal voltage reading will be more like 13.5 volts DC. When you turn on lights, heater and other devices, the output voltage may drop below 13.0 volts. This is normal in most cars.
Swez
PS If you want more sub power, a better amp would really improve your bass performance. In fact, this amp may sound better bridged with only 1 sub connected... assuming your box is sealed and each sub has its own sealed chamber. Try it!
eldevioso on 11/18/2003 13:55:08
Thanks a lot. Here's a little additional information that may have helped.
As far as the subs being out of sync: I'm almost positive they're wired correctly and it's not so much out of sync but less excursion on one speaker so it appears to be out of sync. But nevertheless I'll double check the wiring. Another factor is that one sub is years old and the other is brand new and there is an appropriate difference in "stiffness" of the speaker. Could this be what's causing the problem...It appears to be simply a visual problem, not a sound problem.
Swez: thanks for the input. I actually had a single sub running off the amp bridged, and it did sound close to what it sounds like now, which I assume is because it was getting much more power. However, these subs handle 400wRMS and from what I hear, Cerwin Vega subs really "like" power to perform well. Oh well, I think my problem is that I need a much bigger amp, I just wasn't planning on running dual 12s when I first put it all together. I guess the bug just caught me and I couldn't stop myself :)
As for my boxes, I built two custom tubes. They're built to spec at 2.22 cu ft of airspace and are air tight, aside from the huge 4" diameter 10.75' long port in the back of each one. The tubes are I think 14" diameter by just about 26" long, and I decided to go with only 1/2" wood pieces for the ends as the "tube" design minimizes forces on the wood walls. Further, the end piece that does receive the pressure of the woofer is 14" diameter circle and is 1/2" thick. I don't think it can flex at all. I chose ported enclosure because Vega doesn't provide sealed dimensions for these subs saying that they're designed for bassreflex vented enclosures. This introduces another question I had.
I was forced by design to place the port of the tube directly in the back of the speaker (i.e. at the opposite end of the tube, the back compared to the face of the tube). what are your opinions on the effectiveness of the port in this location, despite the fact there is no alternative with this design. From an untechnical point of view, I will say that It seems to hit appropriately and the sound is rich until i get high in the volume and my "overworked" amp starts distorting?
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