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#1
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
Ok, so I'm reading the manual of the Pioneer DEH-P3800MP and it's showing
that it can drive a subwoofer just off of headunit power (70W output)? But my research is also showing that many subwoofers need well over 100W power RMS. So, are there actually subwoofers out there that can be driven by this headunit without an amp? Or is this more of "proof of concept" function (e.g., yes, the unit can *technically* drive a subwoofer) and in all reality, an amp is actually required (as I would expect it to be required) to drive subwoofers to their opimum output? |
#2
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
I can't download the owner's manual because pioneer is dumb and makes you log in, but http://tinyurl.com/yzrard says it's just the normal 50 x 4 max, 22 x 4 rms. sure you can drive a sub with it, it's just like any other amplifier, but.....you'll only get 22 watts. -- KU40 |
#3
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
he is wrong about getting only 22watts.you may get more/les depending on
electrical system. |
#4
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
bob wald wrote:
he is wrong about getting only 22watts.you may get more/les depending on electrical system. Which is really irrelevant... the reality of it is, ANY head unit CAN "drive a subwoofer". Whether it can drive it any usable level is the question, and the answer is just about universally "no". A very efficient small (8") sub MIGHT be audible with 70W of deck power, but wouldn't really give you any acceptable bass. I wouldn't automatically say 70W isn't enough - Bob is partly right, it can vary (a little bit) with the electrical system, but also depends on the design of the amp. I used to have a Rodek amp that was *rated* 2x30W, but it could draw up to 10A and SHOOK my little Mazda driving only a pair of 8" Orion subs. When I was installing in a shop, we did a system in one guy's car that used Quart separates in all four corners, and a huge box with four 12" M&M subs in isobaric pairs, and four 8" M&Ms off to the sides, all driven by two Autotek amps that were *rated* at 4x22W but could run 1-ohm stable. Tuned for flat response, the car still exceeded 140dB SPL with pink noise (the owner fiddled with the system before he took it down to the soundoff and completely tanked everything but the SPL comps.... idiot). So yes, 70W COULD drive a sub... but I wouldn't count on it being able to actually deliver that kind of power, and certainly not to deliver and sort of significant current. |
#5
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
bob wald Wrote: he is wrong about getting only 22watts.you may get more/les depending on electrical system. give me a frickin break bob. I have yet to run into a vehicle that can't run a head unit and it's tremendous 10 amps maximum current draw. An automotive battery by itself could run a head unit at maximum volume by itself for hours. -- KU40 |
#6
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
"Matt Ion" wrote in message
news:YfuYg.146634$R63.73986@pd7urf1no... bob wald wrote: he is wrong about getting only 22watts.you may get more/les depending on electrical system. Which is really irrelevant... the reality of it is, ANY head unit CAN "drive a subwoofer". Whether it can drive it any usable level is the question, and the answer is just about universally "no". A very efficient small (8") sub MIGHT be audible with 70W of deck power, but wouldn't really give you any acceptable bass. [snip...] That's what I was thinking, but I thought I'd ask for sure. More specifically, here's what Pioneer has in the manual under the Audio section: Continuous power output is 22W per channel minimum into 4 ohms, both channels driven 50 to 15000 Hz with no more than 5% THD. Maximum power output....... 50W x 4 50W x 2/4 ohm + 70W X 1/2 ohm (for subwoofer) Load Impedance........ 4 - 8 ohms x 4 4 - 8 ohms x 2 + 2 ohms x 1 (then a bunch of equalizer specifications) Subwoofer: Frequency........ 50/63/80/100/125 Hz Slope............ -18 dB/oct Gain............. +/-12 dB Phase............ Normal/Reverse Also, since I'm seeing that even the cheapest (4 ohm) sub available (something like an 8 inch Roadmaster RSW80 which only goes down to 40 Hz and is definitly not a high end sub by any means) is rated at 80W RMS/200W peak, while something of much higher quality like a 12 inch Pioneer TS-W301R is 800 W max power (and I'll assume well over 100 W RMS power recommended to get decent bass output): no I don't think I'll drive a subwoofer off of headunit power unless I can actually find a decent 2 ohm sub that the headunit can drive without serious clipping issues. |
#7
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
I don't think anyone's mentioned this yet so I will.
First, as Matt and KU40 said, ANY HU can drive a subwoofer, it's just how much output you will get is likely to not be much at 22 watts RMS. BUT WHAT YOU CANNOT DO WITH A HU IS BRIDGE TWO CHANNELS INTO ONE TO DRIVE YOUR SUB (unlike most two channel amplifiers). There are no HU's out there (that I know of) that are 2 ohm stable and if you try to do this you will likely fry your HU (or at least throw it into protection mode). Perhaps you know this already. I bring it up because if someone were to try to drive a single sub with a HU there would be a natural inclination to want to use two of the four channels to drive the sub/subs (I mean, what do you do with THREE left over channels?). Of course, if you are driving two 4 ohm subs, you can simply use one channel of your HU for one sub and another channel for the other. JUST DON'T BRIDGE. MOSFET "Daniel W. Rouse Jr." wrote in message ... Ok, so I'm reading the manual of the Pioneer DEH-P3800MP and it's showing that it can drive a subwoofer just off of headunit power (70W output)? But my research is also showing that many subwoofers need well over 100W power RMS. So, are there actually subwoofers out there that can be driven by this headunit without an amp? Or is this more of "proof of concept" function (e.g., yes, the unit can *technically* drive a subwoofer) and in all reality, an amp is actually required (as I would expect it to be required) to drive subwoofers to their opimum output? |
#8
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
Load Impedance........
4 - 8 ohms x 4 4 - 8 ohms x 2 + 2 ohms x 1 Hold the phone..... 2 ohm stable? It appear that you CAN bridge channels 3 and 4 into one channel as those two channels appear to be 2 ohm stable. Disregard my other post regarding bridging. Clearly, you WOULD get MUCH more than 22 watts for your sub if you did this (bridge those two channels). Matt and KU40, is that how it appears to you guys? MOSFET |
#9
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
hmm, I've never seen a head unit that can drive that low of an impedence load, nor one that can drop below 4 ohms if bridged (which I'm not sure is an option yet). Especially on a 130 dollar head unit. seems a little iffy to me, even moreso since it's not listed as a feature on their product description. but at any rate, driving any decent subwoofer with a head unit is not a very good option. Just get an amp. -- KU40 |
#10
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
Especially on a 130 dollar head unit. seems a
little iffy to me, even moreso since it's not listed as a feature on their product description. but at any rate, driving any decent subwoofer with a head unit is not a very good option. Just get an amp. Good advice, I didn't know it was a $130 HU. Yes, that does make it sound more iffy to me as well. But, on the other hand, with amplifier technology becoming ever more efficient (Class D, Class T, etc.) and smaller, WHY NOT build a HU that can be bridged to drive a sub? It's not a bad idea. MOSFET |
#11
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
MOSFET wrote:
BUT WHAT YOU CANNOT DO WITH A HU IS BRIDGE TWO CHANNELS INTO ONE TO DRIVE YOUR SUB (unlike most two channel amplifiers). That's correct. You cannot bridge HU channels because they are ALREADY bridged by design. That's the only way to have more than 5 watts per channel with a 12 volts supply. Stand alone amps CAN and indeed HAVE more than this because their power supplies kinda "fabricate" higher rail voltage. This is impossible in a HU because of unsufficient space and heat dissipation capability, as well as price point considerations. Of course, if you are driving two 4 ohm subs, you can simply use one channel of your HU for one sub and another channel for the other. JUST DON'T BRIDGE. Another possibility is using a dual voice coil sub. My "short on cash" brother use such a system in his truck and even if the sound is not that loud, you immediately know by hearing that a 12 inches is hiding somewhere! -- Eric (Dero) Desrochers http://homepage.mac.com/dero72 Hiroshima 45, Tchernobyl 86, Windows 95 |
#12
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
Well Eric, what about this 2 ohm stable spec. that the OP gave?
Do you buy it? Do you think he can bridge channels 3 and 4? MOSFET |
#13
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
"MOSFET" wrote in message ... Well Eric, what about this 2 ohm stable spec. that the OP gave? Do you buy it? Do you think he can bridge channels 3 and 4? MOSFET Pioneer has had some units in the last 4-5 years that the rear channels were bridgeable for subwoofer |
#14
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
Daniel W. Rouse Jr. wrote:
"Matt Ion" wrote in message news:YfuYg.146634$R63.73986@pd7urf1no... bob wald wrote: he is wrong about getting only 22watts.you may get more/les depending on electrical system. Which is really irrelevant... the reality of it is, ANY head unit CAN "drive a subwoofer". Whether it can drive it any usable level is the question, and the answer is just about universally "no". A very efficient small (8") sub MIGHT be audible with 70W of deck power, but wouldn't really give you any acceptable bass. [snip...] That's what I was thinking, but I thought I'd ask for sure. More specifically, here's what Pioneer has in the manual under the Audio section: Continuous power output is 22W per channel minimum into 4 ohms, both channels driven 50 to 15000 Hz with no more than 5% THD. Maximum power output....... 50W x 4 50W x 2/4 ohm + 70W X 1/2 ohm (for subwoofer) Okay, I see... it looks like they're actually bridging one pair of channels for a sub output. The fact that bridging should normally approximately double the power of those two channels into the same load, but instead is increasing less than 50%, and into half the load, is telling: that thing is NOT going to deliver much current. Not surprising: there simply isn't room inside a head unit for the size of switching power supply and high-current transistors necessary to deliver any kind of decent power. |
#15
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
Eric Desrochers wrote:
MOSFET wrote: BUT WHAT YOU CANNOT DO WITH A HU IS BRIDGE TWO CHANNELS INTO ONE TO DRIVE YOUR SUB (unlike most two channel amplifiers). That's correct. You cannot bridge HU channels because they are ALREADY bridged by design. That's the only way to have more than 5 watts per channel with a 12 volts supply. Stand alone amps CAN and indeed HAVE more than this because their power supplies kinda "fabricate" higher rail voltage. This is impossible in a HU because of unsufficient space and heat dissipation capability, as well as price point considerations. It certainly is POSSIBLE to put a switching supply inside a head unit (to "fabricate" higher rail voltage). It's not PRACTICAL to make one that delivers any significant amount of current. |
#16
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
MOSFET wrote:
Especially on a 130 dollar head unit. seems a little iffy to me, even moreso since it's not listed as a feature on their product description. but at any rate, driving any decent subwoofer with a head unit is not a very good option. Just get an amp. Good advice, I didn't know it was a $130 HU. Yes, that does make it sound more iffy to me as well. But, on the other hand, with amplifier technology becoming ever more efficient (Class D, Class T, etc.) and smaller, WHY NOT build a HU that can be bridged to drive a sub? It's not a bad idea. Regardless of how efficient you make the amp, output power is still a function of voltage vs. current. Even with a 100% efficient system, power in has to equal power out, and the output stages of the amp itself have to be able to handle that power. That means sufficient cooling (typically big heat sinks) for relatively large transistors in the output stage. No matter what you do, there's just not room inside a standard head unit for an output stage that can deliver any significant power. Maybe if you started looking at double-DIN-sized HUs and some kind of liquid cooling for the output stages, you could get closer... but then you're a bit out of the $150 range |
#17
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
Matt Ion wrote:
Regardless of how efficient you make the amp, output power is still a function of voltage vs. current. Even with a 100% efficient system, power in has to equal power out, and the output stages of the amp itself have to be able to handle that power. That means sufficient cooling (typically big heat sinks) Err, a 100% efficient amp would dissipate NO HEAT, by definition. -- Eric (Dero) Desrochers http://homepage.mac.com/dero72 Hiroshima 45, Tchernobyl 86, Windows 95 |
#18
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
MOSFET wrote:
Well Eric, what about this 2 ohm stable spec. that the OP gave? 2 ohm stable have nothing to do with bridgeable. Most home stereos can tolerate a 4 ohms load even if designed to operate at 8 ohms. That doesn't mean you can bridge them! Do you buy it? Do you think he can bridge channels 3 and 4? I'm not familiar with this unit and i'm too lazy to look-up a spec sheet right now! Typically, HU are using BTL outputs (ie bridged). You cannot bridge something that is already bridged! The only way they could do it is by using a small PWM supply (like in outboard amps) and using "normal" , non-bridged outputs. I seriously doubt they can do it in a 150$ HU. Maybe, just *maybe* they are suggesting using the + from channel 3 with the - of channel 4. It won't give you any more power but will derive a correctly summed mono channel. But please, don't try this at home unless your owner manual clearly state you can! Also, I think it's possible for this 4 X 50 watts (max) unit to put out 4 X 70 watts (max) into 2 ohms (ie about 35 watts rms per channel). -- Eric (Dero) Desrochers http://homepage.mac.com/dero72 Hiroshima 45, Tchernobyl 86, Windows 95 |
#19
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
"MOSFET" wrote in message
... Well Eric, what about this 2 ohm stable spec. that the OP gave? Do you buy it? Do you think he can bridge channels 3 and 4? MOSFET I can confirm that I am not able to bridge the rear speaker channels, if by bridging that means connecting (splicing) both (+) together and separately, splicing both (-) together. I re-checked the Installation Manual and it has the following warning: Since a unique BPTL circuit is employed, never wire so the speaker leads are directly grounded or the left and right (-) speaker leads are common. |
#20
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
"MOSFET" wrote in message
m... Especially on a 130 dollar head unit. seems a little iffy to me, even moreso since it's not listed as a feature on their product description. but at any rate, driving any decent subwoofer with a head unit is not a very good option. Just get an amp. Good advice, I didn't know it was a $130 HU. Yes, that does make it sound more iffy to me as well. But, on the other hand, with amplifier technology becoming ever more efficient (Class D, Class T, etc.) and smaller, WHY NOT build a HU that can be bridged to drive a sub? It's not a bad idea. That's why I'm hoping this may actually work. For a $130 HU, this deck plays MP3/WMA/WAV in addition to standard CD's, and also gets decent AM/FM reception, but the Front Image Enhancer (FIE) function isn't outputting enough clear low bass (for me anyway) through rear full-range speakers. Turning the volume up loud enough, around 42 out of 62, with the FIE enabled starts obvious clipping when playing CD's. The bass doesn't have to seriously boom, though, it just has to blend in with the rest of the frequencies without being either overpowering or underpowered. On the other hand, I'm also prepared to start researching amps, since this HU also has preamp outputs. |
#21
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
"Eric Desrochers" wrote in message
... MOSFET wrote: BUT WHAT YOU CANNOT DO WITH A HU IS BRIDGE TWO CHANNELS INTO ONE TO DRIVE YOUR SUB (unlike most two channel amplifiers). That's correct. You cannot bridge HU channels because they are ALREADY bridged by design. That's the only way to have more than 5 watts per channel with a 12 volts supply. Stand alone amps CAN and indeed HAVE more than this because their power supplies kinda "fabricate" higher rail voltage. This is impossible in a HU because of unsufficient space and heat dissipation capability, as well as price point considerations. Of course, if you are driving two 4 ohm subs, you can simply use one channel of your HU for one sub and another channel for the other. JUST DON'T BRIDGE. Another possibility is using a dual voice coil sub. My "short on cash" brother use such a system in his truck and even if the sound is not that loud, you immediately know by hearing that a 12 inches is hiding somewhere! For a dual voice coil sub, that would be putting one rear channel output into one voice coil input and another rear channel output into the other voice coil input, right? |
#22
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
The rear channels only, do bridge to drive a sub with a killer 70 watts peak
power rating. |
#23
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
You can use either the rear left or rear right outputs to hook up to your sub.
Make sure that you have the HU set to rear sub mode this will place the rears into monaural mode. In article , "Daniel W. Rouse Jr." wrote: "MOSFET" wrote in message ... Well Eric, what about this 2 ohm stable spec. that the OP gave? Do you buy it? Do you think he can bridge channels 3 and 4? MOSFET I can confirm that I am not able to bridge the rear speaker channels, if by bridging that means connecting (splicing) both (+) together and separately, splicing both (-) together. I re-checked the Installation Manual and it has the following warning: Since a unique BPTL circuit is employed, never wire so the speaker leads are directly grounded or the left and right (-) speaker leads are common. |
#24
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
Unless your sub has dual 2ohm voice coils that are wired for a 4ohm load,
you're **** out of luck. If you wire the rear into anything less then a 4ohm load, you'll be out of a hu. Some how I don't think that Pioneer has 12" subs and dual voice coils in mind with this option. Why is this thread so long, this is not rocket science. For a dual voice coil sub, that would be putting one rear channel output into one voice coil input and another rear channel output into the other voice coil input, right? |
#25
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
Daniel W. Rouse Jr. wrote:
I can confirm that I am not able to bridge the rear speaker channels, if by bridging that means connecting (splicing) both (+) together and separately, splicing both (-) together. Bridging is typically done by connecting the speaker to the + output of one channel and the - output of the other. The other two terminals are common internally. |
#26
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
Eric Desrochers wrote:
Matt Ion wrote: Regardless of how efficient you make the amp, output power is still a function of voltage vs. current. Even with a 100% efficient system, power in has to equal power out, and the output stages of the amp itself have to be able to handle that power. That means sufficient cooling (typically big heat sinks) Err, a 100% efficient amp would dissipate NO HEAT, by definition. Err... right, my bad. But since 100% efficiency is impossible, the rest of my point still applies |
#27
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
The fact that bridging should normally approximately double the power of
those two channels into the same load, but instead is increasing less than 50%, and into half the load, is telling: that thing is NOT going to deliver much current. Not surprising: there simply isn't room inside a head unit for the size of switching power supply and high-current transistors necessary to deliver any kind of decent power. Well that's what I thought, too. But I have seen some pretty damn small Class T amps. And yes, heat is an issue as there is no such thing as a 100% efficient amp. But apparently some Class T amps are so efficient their chassis is made of plastic (bazooka had a line of these I believe). PLASTIC FOR PETE'S SAKE!! So perhaps heat would not be a major issue in a HU if you used Class T. MOSFET |
#28
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
This thread is silly, and to compare the workings of a stand alone amplifier
to one of a head unit is just ignorant. Most head unit amplifiers consist on a single IC that delivers 4 channels of amplification. It's just funny to see common sense go out the window. In article , "MOSFET" wrote: The fact that bridging should normally approximately double the power of those two channels into the same load, but instead is increasing less than 50%, and into half the load, is telling: that thing is NOT going to deliver much current. Not surprising: there simply isn't room inside a head unit for the size of switching power supply and high-current transistors necessary to deliver any kind of decent power. Well that's what I thought, too. But I have seen some pretty damn small Class T amps. And yes, heat is an issue as there is no such thing as a 100% efficient amp. But apparently some Class T amps are so efficient their chassis is made of plastic (bazooka had a line of these I believe). PLASTIC FOR PETE'S SAKE!! So perhaps heat would not be a major issue in a HU if you used Class T. MOSFET |
#29
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
Daniel W. Rouse Jr. wrote:
For a dual voice coil sub, that would be putting one rear channel output into one voice coil input and another rear channel output into the other voice coil input, right? Yes, but as another poster said, check that it's a 4 onhm + 4 ohms. -- Eric (Dero) Desrochers http://homepage.mac.com/dero72 Hiroshima 45, Tchernobyl 86, Windows 95 |
#30
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
Err... right, my bad.
But since 100% efficiency is impossible, the rest of my point still applies Of course! But they are getting surprisingly close! The Eclipse XA2000 is reported to have a 91% efficiency at 1/3 power! The thing will produce 200 watts from only 220 watts of power! Dissipating 20 watts is not much more than the average domelight!! -- Eric (Dero) Desrochers http://homepage.mac.com/dero72 Hiroshima 45, Tchernobyl 86, Windows 95 |
#31
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DEH-P3800MP can drive a subwoofer off of HU power?
Captain_Howdy wrote:
This thread is silly, and to compare the workings of a stand alone amplifier to one of a head unit is just ignorant. Most head unit amplifiers consist on a single IC that delivers 4 channels of amplification. It's just funny to see common sense go out the window. A watt is a watt is a watt. That it comes from a tube, a transistor or an IC, Class A, B, AB or D, what difference it makes given the allowed load is respected? If a HU puts out 22 watts at 4 ohms, you could feed it into *any* 4 ohms load, be it a speaker, small or big, a resistor, even a ****ing bulb light, the 22 watts are going to be produced! -- Eric (Dero) Desrochers http://homepage.mac.com/dero72 Hiroshima 45, Tchernobyl 86, Windows 95 |
#32
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DEH-P3800MP can drive a subwoofer off of HU power?
Eric Desrochers wrote:
Captain_Howdy wrote: This thread is silly, and to compare the workings of a stand alone amplifier to one of a head unit is just ignorant. Most head unit amplifiers consist on a single IC that delivers 4 channels of amplification. It's just funny to see common sense go out the window. A watt is a watt is a watt. That it comes from a tube, a transistor or an IC, Class A, B, AB or D, what difference it makes given the allowed load is respected? If a HU puts out 22 watts at 4 ohms, you could feed it into *any* 4 ohms load, be it a speaker, small or big, a resistor, even a ****ing bulb light, the 22 watts are going to be produced! Except that no speaker provides a constant impedence across its entire response curve. A speaker at resonance has an impedence of very close to 0. An amp that can't deliver the necessary CURRENT at that point, will wither and die before long. |
#33
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DEH-P3800MP can drive a subwoofer off of HU power?
partly right? thats like hes partly dead.lol
either i am or not right. lol glad i dont ask advice from you people. lol... as if. also you might get less than 22 if your systems weak. also 21rms to 22.5rms is a big difference. to some. thats per channel....1.5rms= over 6% |
#34
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
Without any respect of how a watt is made, I guess that a watt is a watt. In
that respect we might as well compare head unit amplifiers to nuclear power stations, since a watt is a watt. In article , (Eric Desrochers) wrote: Captain_Howdy wrote: This thread is silly, and to compare the workings of a stand alone amplifier to one of a head unit is just ignorant. Most head unit amplifiers consist on a single IC that delivers 4 channels of amplification. It's just funny to see common sense go out the window. A watt is a watt is a watt. That it comes from a tube, a transistor or an IC, Class A, B, AB or D, what difference it makes given the allowed load is respected? If a HU puts out 22 watts at 4 ohms, you could feed it into *any* 4 ohms load, be it a speaker, small or big, a resistor, even a ****ing bulb light, the 22 watts are going to be produced! |
#35
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
MOSFET wrote: Load Impedance........ 4 - 8 ohms x 4 4 - 8 ohms x 2 + 2 ohms x 1 Hold the phone..... 2 ohm stable? It appear that you CAN bridge channels 3 and 4 into one channel as those two channels appear to be 2 ohm stable. Disregard my other post regarding bridging. Clearly, you WOULD get MUCH more than 22 watts for your sub if you did this (bridge those two channels). Matt and KU40, is that how it appears to you guys? The confusing part, unless the HU has a power supply, 4 channels are allready bridged, You can't double bridge. The HU companies like to rate their components to the max. You can't really get over 20 watts without a power supply. These HU are probably maxed out on the input voltage when they make these claims. greg |
#36
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DEH-P3800MP can drive a subwoofer off of HU power?
Matt Ion wrote:
Except that no speaker provides a constant impedence across its entire response curve. Yeah that's true but it has nothing to do with what the other poster stated. A speaker at resonance has an impedence of very close to 0. Err. Free air or sealed, at the resonance, the excursion is at maximum, the back emf is at maximum, hence the impedance is *maximum*. The point at which the impedance *may* fall below the nominal impedance is in the mid bass range. Do a google search for speaker impedance curve. Here is an fine example : http://www.churchsoundcheck.com/imp1.html In a ported box, the *system* (driver + box + port) impedance will indeed be low at the port resonance. It's logical since the cone motion is nearly 0 at that frequency. But rest assured it stays well over 0 ohms at all time. Else, amps and HU would go in protect mode left and right. I never heard of a 4 ohms nominal driver that goes near 0 in its curve, maybe you have an example, I'd like to see this! An amp that can't deliver the necessary CURRENT at that point, will wither and die before long. True. That's why those who wants better sound will use stand alone amps. But Captain Howdy seemed to imply that HU power was somewhat "particular" and could not under any circonstance feed a sub. Well, it's doable and done, but obviously it's not the way to go for superior sound quality and level. In fact, millions and millions of HU works just fine feeding full range coax, which *also* have a minimum impedance in their curve. Why suddenly a sub would be worst than full range? Hope this helps. -- Eric (Dero) Desrochers http://homepage.mac.com/dero72 Hiroshima 45, Tchernobyl 86, Windows 95 |
#37
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DEH-P3800MP can drive a subwoofer off of HU power?
Eric Desrochers wrote:
Matt Ion wrote: Except that no speaker provides a constant impedence across its entire response curve. Yeah that's true but it has nothing to do with what the other poster stated. A speaker at resonance has an impedence of very close to 0. Err. Free air or sealed, at the resonance, the excursion is at maximum, the back emf is at maximum, hence the impedance is *maximum*. The point at which the impedance *may* fall below the nominal impedance is in the mid bass range. Do a google search for speaker impedance curve. Here is an fine example : http://www.churchsoundcheck.com/imp1.html Oops, you're correct... that's what I get for posting when half asleep. In fact, millions and millions of HU works just fine feeding full range coax, which *also* have a minimum impedance in their curve. Why suddenly a sub would be worst than full range? Well, passive crossovers come into play once you start looking at most multi-way speaker sets... not that it necessarily lowers overall impedence, but they can start introdocing some pretty complex impedence curves, especially with more reactive LC combinations. |
#38
Posted to rec.audio.car
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DEH-P3800MP can drive a subwoofer off of HU power?
bob wald wrote: partly right? thats like hes partly dead.lol either i am or not right. lol glad i dont ask advice from you people. lol... as if. also you might get less than 22 if your systems weak. also 21rms to 22.5rms is a big difference. to some. thats per channel....1.5rms= over 6% God I love bob. There. I said it. I'm "out". |
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