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post #1 of 10 Old 10-04-2019, 03:15 PM - Thread Starter
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Need advice for proper power amp for passive subwoofer

Hi Guys,

My current system almost complete for atmos (jbl fronts, klipsch center, klipsch rear, klipsch back, klipsch atmos height speakers onkyo tx nr 686) I have my own DIY passive subwoofer from old days and I want to buy a proper amp for it (in next months Im planning to buy a new active subwoofer -or- a new DIY subwoofer and complete my HT as 7.4.2)

My current subwoofer driver is Kenwood KFC-WF303 (Max (RMS) Output Power 600 Watt - Frequency Response 25 - 800 Hz - Nominal Impedance 4 Ohm Sensitivity 93 dB 12inch)

Im planning to buy a Behringer power amp (because its easy to find in my area) and I found following models for my budget :

- Behringer KM 750
- Behringer NX 1000 D

What you think guys, which one will be correct amp for my subwoofer ? If KM750 is also ok it will be a cheaper solution for me ? Do you think I need an amp with DSP or is it not necessary ?

Lastly I want to ask your opinions : which way is better ; buying 2 channel amp and use one channel for current passive subwoofer, and use other channel for a new DIY subwoofer instead of buying an active subwoofer ? which one will be a better/cheaper solution?

Im open for other suggestions!

Thanx!
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post #2 of 10 Old 10-05-2019, 07:55 AM
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Quote:
Originally Posted by lovnblack View Post
Hi Guys,

My current system almost complete for atmos (jbl fronts, klipsch center, klipsch rear, klipsch back, klipsch atmos height speakers onkyo tx nr 686) I have my own DIY passive subwoofer from old days and I want to buy a proper amp for it (in next months Im planning to buy a new active subwoofer -or- a new DIY subwoofer and complete my HT as 7.4.2)

My current subwoofer driver is Kenwood KFC-WF303 (Max (RMS) Output Power 600 Watt - Frequency Response 25 - 800 Hz - Nominal Impedance 4 Ohm Sensitivity 93 dB 12inch)

Im planning to buy a Behringer power amp (because its easy to find in my area) and I found following models for my budget :

- Behringer KM 750
- Behringer NX 1000 D

What you think guys, which one will be correct amp for my subwoofer ? If KM750 is also ok it will be a cheaper solution for me ? Do you think I need an amp with DSP or is it not necessary ?

Lastly I want to ask your opinions : which way is better ; buying 2 channel amp and use one channel for current passive subwoofer, and use other channel for a new DIY subwoofer instead of buying an active subwoofer ? which one will be a better/cheaper solution?

Im open for other suggestions!

Thanx!

For a second (or third) sub to pair with your existing, I'd take a look at these:
https://www.chanemusiccinema.com/SBE-118
Cheap enough and good performers from what I've read.


The cheaper amp would work fine for you, you'd be giving up a db or two of output compared to a full 600wpc, it's up to you to decide if the extra cost is worth it. Behringer amps tend to have noisy fans from what I recall, there's quieter options out there if that's a concern for you.


EDIT: I just noticed your driver is a 12", for some reason I thought it was a 15". A nearfield/front stage pairing might work, but maybe consider just moving on to the Chanes?

Last edited by dpc716; 10-05-2019 at 08:03 AM.
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post #3 of 10 Old 10-06-2019, 03:52 PM
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This link as many option;
https://www.amazon.ca/s?k=behringer+...ref=nb_sb_noss
All depending of how money you want to spend, and how much power you require.

Personally, I think this one can serve many people in your situation;
https://www.amazon.ca/Ultra-Lightwei...0402373&sr=8-2

And perhaps, posting here. Can give you more and refine option for your needs;
https://www.avsforum.com/forum/155-diy-speakers-subs/


Darth

Last edited by darthray; 10-06-2019 at 03:59 PM.
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post #4 of 10 Old 10-07-2019, 04:03 PM - Thread Starter
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Originally Posted by dpc716 View Post
For a second (or third) sub to pair with your existing, I'd take a look at these:
https://www.chanemusiccinema.com/SBE-118
Cheap enough and good performers from what I've read.


The cheaper amp would work fine for you, you'd be giving up a db or two of output compared to a full 600wpc, it's up to you to decide if the extra cost is worth it. Behringer amps tend to have noisy fans from what I recall, there's quieter options out there if that's a concern for you.


EDIT: I just noticed your driver is a 12", for some reason I thought it was a 15". A nearfield/front stage pairing might work, but maybe consider just moving on to the Chanes?
Thank you for your suggestion. But because of where I live (in Europe very far away from US), Chanes looks difficult option for me. This question still confuse me (sorry for my bad english) :

- now buy an amp which will be enough and good match for your current passive subwoofer, in next months buy an active subwoofer
- now buy an amp which will be enough for your current passive subwoofer and in next months make a DIY passive subwoofer and drive both of passive subwoofers with that amp

Do I need to match both of subwoofer's watt ohm and dB specs and maybe inches too ? (my receiver have 2 subwoofer output) If they need to be match, then by which one catching that match will be easier (with active or DIY passive subwoofer) ?

And if we decide to go on with 2nd passive subwoofer and drive them enough power amp, then cheaper (behringer km750) will be enough? Why Im asking this question again; because I just realized that expensive one looks lower watt output at 4 ohm -its weird-- I really cant understand, can you please check following compare table for them (plz see fan details also) :

https://www.bhphotovideo.com/c/compa...EG_1427355-REG

It says at 4 ohm cheaper one gives 400W per channel, but expensive one gives 300w per channel. If DSP create that price difference then the question is do I really need DSP or not ? Second certain difference between them cheaper one Class AB, expensive one Class D...its really getting confusing

Please help me to decide...

Regards

Rifat
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post #5 of 10 Old 10-07-2019, 04:14 PM - Thread Starter
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Quote:
Originally Posted by darthray View Post
This link as many option;
https://www.amazon.ca/s?k=behringer+...ref=nb_sb_noss
All depending of how money you want to spend, and how much power you require.

Personally, I think this one can serve many people in your situation;
https://www.amazon.ca/Ultra-Lightwei...0402373&sr=8-2

And perhaps, posting here. Can give you more and refine option for your needs;
https://www.avsforum.com/forum/155-diy-speakers-subs/


Darth
Hi Darth

Thank you! "and how much power you require" yes exactly thats what I also want to know do you think is there a way to move this topic to DIY SPEAKER AND SUBS ?
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post #6 of 10 Old 10-07-2019, 05:36 PM
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Quote:
Originally Posted by lovnblack View Post
Hi Darth

Thank you! "and how much power you require" yes exactly thats what I also want to know do you think is there a way to move this topic to DIY SPEAKER AND SUBS ?
Any Inuke amp should will do, since most have at least 1000 watts
I personally use two 300 watt Amp (not pro stuff), and sometime do run of juice
To move your thread, only a Moderator can do that. Easier to start a new thread, and post again


Darth

Last edited by darthray; 10-07-2019 at 05:39 PM.
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post #7 of 10 Old 10-07-2019, 06:04 PM
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Quote:
Originally Posted by lovnblack View Post
Thank you for your suggestion. But because of where I live (in Europe very far away from US), Chanes looks difficult option for me. This question still confuse me (sorry for my bad english) :

- now buy an amp which will be enough and good match for your current passive subwoofer, in next months buy an active subwoofer
- now buy an amp which will be enough for your current passive subwoofer and in next months make a DIY passive subwoofer and drive both of passive subwoofers with that amp

Do I need to match both of subwoofer's watt ohm and dB specs and maybe inches too ? (my receiver have 2 subwoofer output) If they need to be match, then by which one catching that match will be easier (with active or DIY passive subwoofer) ?

And if we decide to go on with 2nd passive subwoofer and drive them enough power amp, then cheaper (behringer km750) will be enough? Why Im asking this question again; because I just realized that expensive one looks lower watt output at 4 ohm -its weird-- I really cant understand, can you please check following compare table for them (plz see fan details also) :

https://www.bhphotovideo.com/c/compa...EG_1427355-REG

It says at 4 ohm cheaper one gives 400W per channel, but expensive one gives 300w per channel. If DSP create that price difference then the question is do I really need DSP or not ? Second certain difference between them cheaper one Class AB, expensive one Class D...its really getting confusing

Please help me to decide...

Regards

Rifat

You are reading the specs correctly, the Behringer KM 750 has more power. One of the reviewers said the fan is quiet, which is a plus for home use. Buying this and making a second DIY sub would be the cheapest solution by far.


Regarding DSP you would not need it if your receiver has room correction, which yours does, but it is a proprietary product that I have no experience with. So I really don't know how good it is. You could always try it, and if it's not great, get something like the minidsp if you want to do your own adjustments later.


A second DIY sub doesn't have to match your existing exactly, but building something similar would make the most sense if you think that would be enough for you. In other words I wouldn't spring for an 18" to match with a 12". If you think you need more output I would go with 2 18"s and dump the 12, or save it for nearfield duty.


Regarding your two sub outs, what you would most likely do is use one sub out to your Behringer input, and run both of your subs off of the same signal. There are times (placement driven) when you might not do that, but that's what you'd generally do.


If you want to pursue powered sub options, let us know your budget, room dimensions and listening habits.
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post #8 of 10 Old 10-07-2019, 07:38 PM
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Looking at the driver in your existing DIY sub more closely, it looks like the kind of driver you would use in an auto, perhaps in a small box? If that's the case, your sub probably won't play anything under 30hz particularly well and you might want to move on from it... IDK... up to you. Since you have nice speakers and are going atmos, I would consider a sub solution that would get me decent 20hz output if I could afford it.
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post #9 of 10 Old 10-08-2019, 04:41 AM - Thread Starter
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Originally Posted by dpc716 View Post
You are reading the specs correctly, the Behringer KM 750 has more power. One of the reviewers said the fan is quiet, which is a plus for home use. Buying this and making a second DIY sub would be the cheapest solution by far.


Regarding DSP you would not need it if your receiver has room correction, which yours does, but it is a proprietary product that I have no experience with. So I really don't know how good it is. You could always try it, and if it's not great, get something like the minidsp if you want to do your own adjustments later.


A second DIY sub doesn't have to match your existing exactly, but building something similar would make the most sense if you think that would be enough for you. In other words I wouldn't spring for an 18" to match with a 12". If you think you need more output I would go with 2 18"s and dump the 12, or save it for nearfield duty.


Regarding your two sub outs, what you would most likely do is use one sub out to your Behringer input, and run both of your subs off of the same signal. There are times (placement driven) when you might not do that, but that's what you'd generally do.


If you want to pursue powered sub options, let us know your budget, room dimensions and listening habits.
Thank you very much for your clear and helpfull answer. Ok then I will go on with KM750 and will get a 2nd DIY sub soon. I just measure my current sub box dimensions maybe I can upgrade Kenwood driver to another 16inch driver because there is enough space for it.

Lastly, let me ask you (I need to learn so I will not ask and bother other people whenever I need something about subwoofers) If my subwoofer Max RMS power is 600W then I need a 300 or 400W amp, is it correct ? So that, on my 2nd subwoofer DIY project I need to choose sub driver again around 600W max RMS at 4 ohm ?

In this tech spec page of current kenwood driver it says "Peak input power 600W, Rated input power 160W" is that mean, actually this subwoofer nominal power (continious power or however they call) is 160W and because of that our Behringer KM750's one 400W at 4 ohm channel can feed this subwoofer right? I hope you meant with this KM750 amp you can feed both of your DIY subwoofers by saying "Buying this and making a second DIY sub would be the cheapest solution by far." ?

Kenwood subwoofer tech spec page link :
http://www.cieri.net/Documenti/Kenwo...ox%20etc.).pdf

Thanx!
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post #10 of 10 Old 10-08-2019, 06:03 AM
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Thank you very much for your clear and helpfull answer. Ok then I will go on with KM750 and will get a 2nd DIY sub soon. I just measure my current sub box dimensions maybe I can upgrade Kenwood driver to another 16inch driver because there is enough space for it.

Lastly, let me ask you (I need to learn so I will not ask and bother other people whenever I need something about subwoofers) If my subwoofer Max RMS power is 600W then I need a 300 or 400W amp, is it correct ? So that, on my 2nd subwoofer DIY project I need to choose sub driver again around 600W max RMS at 4 ohm ?

In this tech spec page of current kenwood driver it says "Peak input power 600W, Rated input power 160W" is that mean, actually this subwoofer nominal power (continious power or however they call) is 160W and because of that our Behringer KM750's one 400W at 4 ohm channel can feed this subwoofer right? I hope you meant with this KM750 amp you can feed both of your DIY subwoofers by saying "Buying this and making a second DIY sub would be the cheapest solution by far." ?

Kenwood subwoofer tech spec page link :
http://www.cieri.net/Documenti/Kenwo...ox%20etc.).pdf

Thanx!

Both drivers and amps have rated continuous and peak power ratings, and while it's nice if they're aligned, they don't have to be. Referring to your question I bolded, yes that's what I meant.


If you think you might start from scratch DIY, I would second Darth's suggestion and post in the DIY forum. Reason being that HT places demands on a sub that music does not (sub 30hz material in particular) and you would want to choose a driver and box combo that would both optimize output in this range as well as not leave you exposed to overdriving your sub.
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