Impedance question

t0mm1 · 18th January 2012, 06:07 PM

Hi,

I'm quite new at this and not so familiar with the terminology, so please be patient with me.

I am using a (almost) three way car system at home with a Denon amplifier. I have built two boxes, each with a tweeter and a 4" driver. To each box, there is a "filter box". The 4" driver is connected to the mid-range output on the filter-box and the tweeter to the tweeter output (there is a separate filter to the tweeter as well). The input connector on the filter-box is connected to the amplifier.
There is also a "woofer" output on the filter boxes, but I don't have any drivers to connect to these outputs.

When I'm listening to music, I realize that there should be more of the lower frequencies so I'm thinking of buying two 6,5" drivers and connect these to the woofer outputs on the filter-boxes.

My question is how this woofer addition might change the impedance? Higher, lower or the same as before?

The reason why I'm asking is that my Denon sometimes (but not so often) goes into protected mode. Will it get worse or better if I add these 6,5" woofers?

Thanks!

strawberry · 18th January 2012, 06:47 PM

If your filter boxes are designed to work with three drivers, add a woofer, but you may have to put the woofer in a separate cabinet if the mids are not in sealed cups.. Does it say on the filter box what impedance its built for? 5-8 ohm drivers are 8 ohm. 4 ohm and below drivers are 4 ohm. While you are preparing a new cabinet put a 8-10 ohm resistor on the empty filter out put. RadioShack has a good 8 ohm 20 watt resistor. By not having a load connected to a crossover you are shortening the amp. The impedance with a woofer will be the same as before.

t0mm1 · 18th January 2012, 06:55 PM

The woofers will be in a separate cabinet. They does not fit into the same box as the tweeters and mids (2 liters each).
It's a 4 ohm system.

t0mm1 · 18th January 2012, 07:14 PM

Quote:

Originally Posted by strawberry

While you are preparing a new cabinet put a 8-10 ohm resistor on the empty filter out put. RadioShack has a good 8 ohm 20 watt resistor.

There is already a high effect resistor in the filter-box, but it is currently by-passed (connected/unconnected with cables inside the filter-box)

strawberry · 18th January 2012, 07:25 PM

Without looking at the crossover I don't know the purpose of the resistor(s) in the filter box. It could be for your tweeter. I would put a resistor on the woofer output for now. Your amp is not happy as is.

t0mm1 · 18th January 2012, 07:28 PM

Quote:

Originally Posted by strawberry

Without looking at the crossover I don't know the purpose of the resistor(s) in the filter box. It could be for your tweeter. I would put a resistor on the woofer output for now. Your amp is not happy as is.

OK, I will. Thank you for your answers.

strawberry · 18th January 2012, 09:01 PM

You can save money by connecting your 6.5" woofers to the crossover out put and let the woofers stand on top of the existing cabinets while you work on the other cabinets. You get some base and you don't have to buy resistors.

t0mm1 · 21st January 2012, 06:57 PM

Quote:

Originally Posted by strawberry

You can save money by connecting your 6.5" woofers to the crossover out put and let the woofers stand on top of the existing cabinets while you work on the other cabinets. You get some base and you don't have to buy resistors.

I have now bought the woofers.

Sorry for my incompetence; how do you mean when you say "stand on the top of the existing cabinets"? I'm really new at this as you already have realized

Do you mean that I can get a little bit base by just putting them on the table or cabinets with magnet side down?

strawberry · 21st January 2012, 07:49 PM

Yes, if you don't have pets that will gnaw on them or push them down, you can let them stand connected for now on top of your cabinets. The only benefit from this is that you don't have to buy the resistors. They need to be put into cabinets eventually for better sound. But you don't have to. It's a free country.

t0mm1 · 21st January 2012, 08:08 PM

Quote:

Originally Posted by strawberry

Yes, if you don't have pets that will gnaw on them or push them down, you can let them stand connected for now on top of your cabinets. The only benefit from this is that you don't have to buy the resistors. They need to be put into cabinets eventually for better sound. But you don't have to. It's a free country.

I have something even worse than pets... KIDS! They will use pencils to draw on them, and scissors to cut out heart shaped figures from the membrane

Thank you for your answers!

18th January 2012, 06:07 PM	#1
t0mm1 diyAudio Member Join Date: Jan 2012	Impedance question Hi, I'm quite new at this and not so familiar with the terminology, so please be patient with me. I am using a (almost) three way car system at home with a Denon amplifier. I have built two boxes, each with a tweeter and a 4" driver. To each box, there is a "filter box". The 4" driver is connected to the mid-range output on the filter-box and the tweeter to the tweeter output (there is a separate filter to the tweeter as well). The input connector on the filter-box is connected to the amplifier. There is also a "woofer" output on the filter boxes, but I don't have any drivers to connect to these outputs. When I'm listening to music, I realize that there should be more of the lower frequencies so I'm thinking of buying two 6,5" drivers and connect these to the woofer outputs on the filter-boxes. My question is how this woofer addition might change the impedance? Higher, lower or the same as before? The reason why I'm asking is that my Denon sometimes (but not so often) goes into protected mode. Will it get worse or better if I add these 6,5" woofers? Thanks!

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18th January 2012, 06:47 PM	#2
strawberry diyAudio Member Join Date: Dec 2011	If your filter boxes are designed to work with three drivers, add a woofer, but you may have to put the woofer in a separate cabinet if the mids are not in sealed cups.. Does it say on the filter box what impedance its built for? 5-8 ohm drivers are 8 ohm. 4 ohm and below drivers are 4 ohm. While you are preparing a new cabinet put a 8-10 ohm resistor on the empty filter out put. RadioShack has a good 8 ohm 20 watt resistor. By not having a load connected to a crossover you are shortening the amp. The impedance with a woofer will be the same as before.

18th January 2012, 06:55 PM	#3
t0mm1 diyAudio Member Join Date: Jan 2012	The woofers will be in a separate cabinet. They does not fit into the same box as the tweeters and mids (2 liters each). It's a 4 ohm system.

18th January 2012, 07:25 PM	#5
strawberry diyAudio Member Join Date: Dec 2011	Without looking at the crossover I don't know the purpose of the resistor(s) in the filter box. It could be for your tweeter. I would put a resistor on the woofer output for now. Your amp is not happy as is.

18th January 2012, 09:01 PM	#7
strawberry diyAudio Member Join Date: Dec 2011	You can save money by connecting your 6.5" woofers to the crossover out put and let the woofers stand on top of the existing cabinets while you work on the other cabinets. You get some base and you don't have to buy resistors.

21st January 2012, 07:49 PM	#9
strawberry diyAudio Member Join Date: Dec 2011	Yes, if you don't have pets that will gnaw on them or push them down, you can let them stand connected for now on top of your cabinets. The only benefit from this is that you don't have to buy the resistors. They need to be put into cabinets eventually for better sound. But you don't have to. It's a free country.

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