Currently I have two 2-channel amps wired to 2 15" MTX Thunder 6000 SVC 4ohm subs. (1 amp to each sub)
I am trying to figure out if it would be worth my money to buy a mono amp with more watts. Here are the products.
Current Amps: http://www.cardomain.com/item/KENKAC729S
Current Subs: http://reviews.cnet.com/MTX_Thunder_6000_T6154A_car_subwoofer_driver/4507-3425_7-30612528.html?tag=nav
Prospective Amps:
AMP1: http://www.onlinecarstereo.com/CarAudio/ProductDetail.aspx?ProductID=14933
AMP2:
http://www.onlinecarstereo.com/CarAudio/ProductDetail.aspx?ProductID=14934
Replies (11)
Ash on 04/17/2006 05:50:34
It may be worth the switch if those will draw less juice than the ones you are using now. Wiring will be less also. As long as your choice is a class D for the best efficiency.
What are the actual amps you are using now?
swez on 04/17/2006 10:38:11
He noted a pair of Kenwood KAC-729s, one per sub. These amps are likely to draw about 35-38A per each. When bridged MONO, power one sub, that's a good fit, but low efficiency (60%) for power consumption means lots of lost watts due to heat and the Class A/B circuitry.
If you went to the larger Class D amp, (Kenwood KAC-9102D), there's more power available @ 2 ohms and will definitely max out your subs if not careful. Great price here though. Then, you can use one of the 729's to power the front speakers.
Are these subs in sealed or ported box? That matters a lot.
Say more please,
Swez
Black_Rob on 04/17/2006 15:29:22
They are going to be in a sealed box. My space is pretty limited in a 92 Accord
swez on 04/18/2006 00:02:01
Here are the sealed box recommendations from MTX on that series woofer. It looks like your best bet for small sealed and good lows, will be 1.75 cf/sub. The 2.25 cf/sub will deliver deepest low bass for this sub model, but with the pair, this would be a very large enclosure.
http://www.mtx.com/caraudio/products/manualsQuickInstall/subs/T6154A.pdf
Swez
Black_Rob on 04/18/2006 00:18:30
What do all the numbers tell you. Maybe you can put them into easier to understand terms. "F3" "Ripple" "Limited SPL" "Qtc" ....... and what do lower/higher numbers tell me .. like 50Hz opposed to 42Hz ??
swez on 04/18/2006 10:36:11
Most of these terms are not meaningful to the average guy. The key elements to look at are:
Fo = Resonant frequency of sub
F3 = -3dB down point in woofer output performance (Hz.)
Efficiency rating: Expressed as; 88dB SPL @ 1 watt/1 meter distance
Re = DC voice coil resistance (3.7 ohms is a 4 ohm coil)
Hz: Operating frequency of a given driver (Subs are generally running between 35-100 Hz., range)
FYI: When looking for good SQL subs, look at the Resonant Frequency
(Fo) and the F3 point. The lower these numbers, the better. (Ie: A sub with an Fo of say 25 Hz., and an F3 of 45 Hz., or lower, is a good low frequency woofer)
Swez
Black_Rob on 04/18/2006 14:43:39
So then, the lower the F3, the deeper the bass?
Ash on 04/18/2006 20:16:08
Yes, but go too deep and meshed with the cars natural boost, the bass can get muddy with no impact. If your going sealed that is. A good target area for sealed would be about 45-50hz. That is where most cars natural boost usually begins.
As for ported, the lower the better. Say 30-35hz, with a subsonic filter around 25 to 30hz. The natural boost of around 40-45hz can be equalized down a few notches to a more flatter/wider response.
Black_Rob on 04/18/2006 20:22:46
So do you think that one Alpine TypeR 12" sub in a ported box would be louder than 2 15"s in a sealed box?
Ash on 04/18/2006 20:31:13
Hmmm.... That would be hard to say for even though the ported would be more efficient, two 15" would definitely be able to move more air.
The tradeoff could be some volume versus low frequency output. Most definitely you could tune the 12 to some incredible lows with the use of a subsonic filter to aid it. With that kind of power output it will still get loud. That would be more impressive than 2 15". If you ever had a ported box before, then you know what I'm talking about.
swez on 04/18/2006 20:53:32
Yes, that is correct.
If you looked at a woofer performance plot, (LEAP, SPL at 1 watt vs Freq graph) you note the vertical graph is dB of SPL. The horizontal part of the grid is frequency. GOTO:
http://www.mtx.com/caraudio/products/manualsQuickInstall/subs/T6154A.pdf
Have a look at the plot in the MTX file on top of page 2. The left plot is actually 2 plots for a small sealed and a large ported box. The heavy black line shows a peak output for this sub in a 3.0 cf box. That peak is at about 60 Hz., and shows about 94dB of SPL between 50-70 Hz. This is commonly called the Fo point. (Or, resonant frequency in an enclosure) This sub has a Fs (Free air resonance of 30 Hz.)
The F3 for this larger ported box is 42 Hz. The SPL has dropped 3dB (91 dB) and slopes rapidly downward below that point. A small amount of bass boost at 45 Hz., (+3dB) will bring the F3 upward in SPL and the sub will have a nearly flat line from 45 - 80 Hz. This is very desirable range for this sub, but to get it, you need a 3.0 cf box/sub. Huge box here, if you use 2 of these subs. This ports are tuned to 35 Hz.
Now, look at the plot outlined in a light gray line. This is for the more compact 1.75 cf sealed application. The plot curve tracks pretty well with the larger ported box. But, the SPL numbers average about 3 dB less along the plot until about 60 Hz. Then output is pretty much equal to the ported design from ~65 -100 Hz. Here, the Fo is at 93dB of SPL at 60 Hz. The F3 is now 50 Hz.
Also, the Excursion Limited SPL (X-max) is at 119/117dB respectively between the ported and sealed boxes. This means that at 300 watts RMS input power, the sub will reach its maximum physical limits of cone movement. Going beyond that point will eventually damage the sub.
OK, this info shows this sub to be very capable and solid performer within the recommended enclosure specs and power limits. However, to get this performance, one needs a fairly large box to get there. However, there are many subs out there that can go lower, have more SPL output and require a smaller enclosure.
If space is an issue for your sub enclosure, other newer subs can not only handle more power and have higher SPL #'s, but they require a smaller enclosure space as well. The older technology subs like the MTX 6000 series, are better geared for larger enclosures, to get that heavy, deep bass some crave.
Got it?
Swez
PS The Kenwood KAC-729s is a good match for this sub in power output. However, they consume additonal current as they are Class A/B audio amps. (~60% eff, 40% losses to heat, ect.) Power consumption here would be about 75 amperes of current x voltage = 75A's x 14.4 volts = 1080 watts input, 600 watts RMS output @ 4 ohms. (both amps running at full output)
A solid Class D amp of 600 watts RMS @ 2 ohms (Say the older JBL BP-600.1) would give the same performance SPL and is >80% eff. This Class D amp comsumes less power yet provides same output as noted above. Here's the efficiency breakdown.
57A's x 14.4 volts = 820.8 watts consumed, 657 watts RMS at 2 ohms.
See the big difference in eff% levels between your 2 Class A/B amps VS a single Class D amp with same watts RMS output? COFFEE
I am trying to figure out if it would be worth my money to buy a mono amp with more watts. Here are the products.
Current Amps: http://www.cardomain.com/item/KENKAC729S
Current Subs: http://reviews.cnet.com/MTX_Thunder_6000_T6154A_car_subwoofer_driver/4507-3425_7-30612528.html?tag=nav
Prospective Amps:
AMP1: http://www.onlinecarstereo.com/CarAudio/ProductDetail.aspx?ProductID=14933
AMP2:
http://www.onlinecarstereo.com/CarAudio/ProductDetail.aspx?ProductID=14934
Replies (11)
Ash on 04/17/2006 05:50:34
It may be worth the switch if those will draw less juice than the ones you are using now. Wiring will be less also. As long as your choice is a class D for the best efficiency.
What are the actual amps you are using now?
swez on 04/17/2006 10:38:11
He noted a pair of Kenwood KAC-729s, one per sub. These amps are likely to draw about 35-38A per each. When bridged MONO, power one sub, that's a good fit, but low efficiency (60%) for power consumption means lots of lost watts due to heat and the Class A/B circuitry.
If you went to the larger Class D amp, (Kenwood KAC-9102D), there's more power available @ 2 ohms and will definitely max out your subs if not careful. Great price here though. Then, you can use one of the 729's to power the front speakers.
Are these subs in sealed or ported box? That matters a lot.
Say more please,
Swez
Black_Rob on 04/17/2006 15:29:22
They are going to be in a sealed box. My space is pretty limited in a 92 Accord
swez on 04/18/2006 00:02:01
Here are the sealed box recommendations from MTX on that series woofer. It looks like your best bet for small sealed and good lows, will be 1.75 cf/sub. The 2.25 cf/sub will deliver deepest low bass for this sub model, but with the pair, this would be a very large enclosure.
http://www.mtx.com/caraudio/products/manualsQuickInstall/subs/T6154A.pdf
Swez
Black_Rob on 04/18/2006 00:18:30
What do all the numbers tell you. Maybe you can put them into easier to understand terms. "F3" "Ripple" "Limited SPL" "Qtc" ....... and what do lower/higher numbers tell me .. like 50Hz opposed to 42Hz ??
swez on 04/18/2006 10:36:11
Most of these terms are not meaningful to the average guy. The key elements to look at are:
Fo = Resonant frequency of sub
F3 = -3dB down point in woofer output performance (Hz.)
Efficiency rating: Expressed as; 88dB SPL @ 1 watt/1 meter distance
Re = DC voice coil resistance (3.7 ohms is a 4 ohm coil)
Hz: Operating frequency of a given driver (Subs are generally running between 35-100 Hz., range)
FYI: When looking for good SQL subs, look at the Resonant Frequency
(Fo) and the F3 point. The lower these numbers, the better. (Ie: A sub with an Fo of say 25 Hz., and an F3 of 45 Hz., or lower, is a good low frequency woofer)
Swez
Black_Rob on 04/18/2006 14:43:39
So then, the lower the F3, the deeper the bass?
Ash on 04/18/2006 20:16:08
Yes, but go too deep and meshed with the cars natural boost, the bass can get muddy with no impact. If your going sealed that is. A good target area for sealed would be about 45-50hz. That is where most cars natural boost usually begins.
As for ported, the lower the better. Say 30-35hz, with a subsonic filter around 25 to 30hz. The natural boost of around 40-45hz can be equalized down a few notches to a more flatter/wider response.
Black_Rob on 04/18/2006 20:22:46
So do you think that one Alpine TypeR 12" sub in a ported box would be louder than 2 15"s in a sealed box?
Ash on 04/18/2006 20:31:13
Hmmm.... That would be hard to say for even though the ported would be more efficient, two 15" would definitely be able to move more air.
The tradeoff could be some volume versus low frequency output. Most definitely you could tune the 12 to some incredible lows with the use of a subsonic filter to aid it. With that kind of power output it will still get loud. That would be more impressive than 2 15". If you ever had a ported box before, then you know what I'm talking about.
swez on 04/18/2006 20:53:32
Yes, that is correct.
If you looked at a woofer performance plot, (LEAP, SPL at 1 watt vs Freq graph) you note the vertical graph is dB of SPL. The horizontal part of the grid is frequency. GOTO:
http://www.mtx.com/caraudio/products/manualsQuickInstall/subs/T6154A.pdf
Have a look at the plot in the MTX file on top of page 2. The left plot is actually 2 plots for a small sealed and a large ported box. The heavy black line shows a peak output for this sub in a 3.0 cf box. That peak is at about 60 Hz., and shows about 94dB of SPL between 50-70 Hz. This is commonly called the Fo point. (Or, resonant frequency in an enclosure) This sub has a Fs (Free air resonance of 30 Hz.)
The F3 for this larger ported box is 42 Hz. The SPL has dropped 3dB (91 dB) and slopes rapidly downward below that point. A small amount of bass boost at 45 Hz., (+3dB) will bring the F3 upward in SPL and the sub will have a nearly flat line from 45 - 80 Hz. This is very desirable range for this sub, but to get it, you need a 3.0 cf box/sub. Huge box here, if you use 2 of these subs. This ports are tuned to 35 Hz.
Now, look at the plot outlined in a light gray line. This is for the more compact 1.75 cf sealed application. The plot curve tracks pretty well with the larger ported box. But, the SPL numbers average about 3 dB less along the plot until about 60 Hz. Then output is pretty much equal to the ported design from ~65 -100 Hz. Here, the Fo is at 93dB of SPL at 60 Hz. The F3 is now 50 Hz.
Also, the Excursion Limited SPL (X-max) is at 119/117dB respectively between the ported and sealed boxes. This means that at 300 watts RMS input power, the sub will reach its maximum physical limits of cone movement. Going beyond that point will eventually damage the sub.
OK, this info shows this sub to be very capable and solid performer within the recommended enclosure specs and power limits. However, to get this performance, one needs a fairly large box to get there. However, there are many subs out there that can go lower, have more SPL output and require a smaller enclosure.
If space is an issue for your sub enclosure, other newer subs can not only handle more power and have higher SPL #'s, but they require a smaller enclosure space as well. The older technology subs like the MTX 6000 series, are better geared for larger enclosures, to get that heavy, deep bass some crave.
Got it?
Swez
PS The Kenwood KAC-729s is a good match for this sub in power output. However, they consume additonal current as they are Class A/B audio amps. (~60% eff, 40% losses to heat, ect.) Power consumption here would be about 75 amperes of current x voltage = 75A's x 14.4 volts = 1080 watts input, 600 watts RMS output @ 4 ohms. (both amps running at full output)
A solid Class D amp of 600 watts RMS @ 2 ohms (Say the older JBL BP-600.1) would give the same performance SPL and is >80% eff. This Class D amp comsumes less power yet provides same output as noted above. Here's the efficiency breakdown.
57A's x 14.4 volts = 820.8 watts consumed, 657 watts RMS at 2 ohms.
See the big difference in eff% levels between your 2 Class A/B amps VS a single Class D amp with same watts RMS output? COFFEE
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