Help needed on stereo amp to subwoofer connection

[kcnanand]

I am currently building a LJM L15D based stereo amp. I have a small 8 inch active subwoofer with both RCA and High level inputs. I want to connect my sub to the stereo amp. I need help/suggestions on:
1. Split output at the stereo preamp to rca in of the subwoofer. Is it possible?, will it affect output / increase load on the preamp. The idea is to have the amp volume work for the subwoofer too.
2. Split the input, Have a dedicated stereo preamp to rca in of the subwoofer. will it work? will have a separate volume control for subwoofer at the amp.
3. Connect line out of stereo to speaker lvl input at the subwoofer. The subwoofer is rated at 150w whereas the amp output at 4ohm will be 250w. will it damage the subwoofer inbuilt amp?
Thanks

 

[efernand1]

Hi,

If your sub has high level inputs then connect regular L+R wires from the amp to the high level inputs of the sub and the out terminals of the sub (L+R) to the speakers..

That's the way to do it...all the best

 

[MaSh]

I am currently building a LJM L15D based stereo amp. I have a small 8 inch active subwoofer with both RCA and High level inputs. I want to connect my sub to the stereo amp. I need help/suggestions on:
1. Split output at the stereo preamp to rca in of the subwoofer. Is it possible?, will it affect output / increase load on the preamp. The idea is to have the amp volume work for the subwoofer too.
2. Split the input, Have a dedicated stereo preamp to rca in of the subwoofer. will it work? will have a separate volume control for subwoofer at the amp.
3. Connect line out of stereo to speaker lvl input at the subwoofer. The subwoofer is rated at 150w whereas the amp output at 4ohm will be 250w. will it damage the subwoofer inbuilt amp?
Thanks

Which sub do you have? Can you post a picture of its rear panel. If you have speaker out on the sub then your Job is easy. If not then you need to do some juggling. Next easier step would be to use A and B speaker channels on your stereo amp.

MaSh

 

[kcnanand]

Which sub do you have? Can you post a picture of its rear panel. If you have speaker out on the sub then your Job is easy. If not then you need to do some juggling. Next easier step would be to use A and B speaker channels on your stereo amp.
MaSh

It is a car sub. Blaupunkt GTB 8200 A. Since it is doing almost no duty on the car planning to use it to complement the stereo speakers for low freq. The rear panel has high level and rca input.
the LJM L15D is supposed to output 250w at 4 ohm. the subwoofer amp is rated 100w. is it safe to run the speaker out of the amp to the high in of the sub. or use a preamp to Rca Line in of the sub.

I do not want to have a dedicated sub for the stereo speakers as the floor standers itself produce decent and clean bass except for the very low levels and the use is only for stereo music.

 

[all4music]

you can't use speaker output on this sub [if you do, you'll end up feeding only the sub from amp: you can't connect your speakers after that].
your best option is to use a quality Y splitter after preamp. i use MX ones, it serves the purpose perfectly.

 

[kcnanand]

you can't use speaker output on this sub [if you do, you'll end up feeding only the sub from amp: you can't connect your speakers after that].
your best option is to use a quality Y splitter after preamp. i use MX ones, it serves the purpose perfectly.

1.As far as i have read, splitting the output from the amp and running one set of wires to the speakers and another set to the active sub is how it is generally done in stereo amps. Since the sub has inbuilt amp, it is supposed to put no load on the stereo amplifier.
2.Y splitter means - i can take two outputs from the preamp. Thanks. so now i have the option to split preamp output or use seperate preamp.
thanks

 

[MaSh]

It is a car sub. Blaupunkt GTB 8200 A. Since it is doing almost no duty on the car planning to use it to complement the stereo speakers for low freq. The rear panel has high level and rca input.
the LJM L15D is supposed to output 250w at 4 ohm. the subwoofer amp is rated 100w. is it safe to run the speaker out of the amp to the high in of the sub. or use a preamp to Rca Line in of the sub.

I do not want to have a dedicated sub for the stereo speakers as the floor standers itself produce decent and clean bass except for the very low levels and the use is only for stereo music.

Oh that makes it even more difficult. How are you going to power it?

What is your source? You can try adding a Y splitter at the source's RCA out and send one line to RCA Line in of the Sub and other line to the stereo amp.

MaSh

 

[kcnanand]

Will power it with a 12v 20amp smps that I have

Sent from my XT1572 using Tapatalk

 

[all4music]

1.As far as i have read, splitting the output from the amp and running one set of wires to the speakers and another set to the active sub is how it is generally done in stereo amps. Since the sub has inbuilt amp, it is supposed to put no load on the stereo amplifier.
2.Y splitter means - i can take two outputs from the preamp. Thanks. so now i have the option to split preamp output or use seperate preamp.
thanks

speaker input on that sub is meant for highlevel input - usually off your car's HU and i've not come across any example of feeding amp input - might work for amp input too. you can as well split the RCA out of the HU in that case.

on the other hand, few home powered audio subs have provision to pass the speaker output through the sub - sub is in series between amp and speakers. it would only 'read' the signal passing through it.

 

[kcnanand]

speaker input on that sub is meant for highlevel input - usually off your car's HU and i've not come across any example of feeding amp input - might work for amp input too. you can as well split the RCA out of the HU in that case.

on the other hand, few home powered audio subs have provision to pass the speaker output through the sub - sub is in series between amp and speakers. it would only 'read' the signal passing through it.

High level input is direct from car speaker output and the RCA input is for sub out/pre out. that is how it is currently connected and i am clear about it.
My basic doubt is will the existing stereo preamp be able to run both the sub and the stereo or a seperate stereo preamp will be needed. i have two spare preamp board. will check it out tomorrow