Technical audio question
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This is a discussion on Technical audio question within the Electronics/Car Audio forums, part of the Interior Mods category; Does anyone know enough about amplifier circuitry to tell me if I can or can not hook up 2 separate ...

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    Registered User boosted scoob's Avatar
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    Question Technical audio question

    Does anyone know enough about amplifier circuitry to tell me if I can or can not hook up 2 separate amplifiers to the same speaker.

    Here's my situation...
    I have a pioneer 400W 4Ch amplifier running aftermarket front/rear speakers for the stereo. Now I have this BT (bluetooth) Sony Ericcson car kit that has a speaker output for a crappy little speaker that it came with. But I want my phone conversations to come through the car speakers. I have looked into the add-on kit that Ericcson sells to enable this, but it only works with factory radios w/ ISO connectors. My headunit is only RCA out to my amps. So I tried and splicing the speaker outputs off of the crappy speaker and into my speaker level inputs on my amplifier and it worked! Only because the kit mutes the radio anytime it makes any sounds through the speaker. I still don't know if it's bad to have both the speaker level and RCA level slots taken up on my amplifier, but I'd say as long as one slot is producing signal and the other is muted, it should be fine. However, my radio puts out 4V RCA and i'm sure the speaker output from the kit only is like 1V or less. So needless to say the volume is quite low. So what I want to do is get a speaker level to RCA converter and have the kit plug into that, then the RCA's from that into a separate small 50W amplifier and then to the front speakers. But then there would be 2 amplifiers connected to the front speakers. Would the amplifier's short/burn themselves out because they are both putting out power? I am afraid mostly for the new 50W amplifier I will buy cause it will be getting the 400W power from my stereo amp through its (the 50W amp) outputs!!! See what I mean? Or can someone disprove me and tell me that it wont matter. Thanks.
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    Registered User hybrid gti 2's Avatar
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    does not sound like it would work to have two amps power one speaker. likly would blow one of the amps. but I could be totally wrong on that. but sound quality would likly suffer if it was possible. if it was me time to shop ebay and find a biger amp. I got a sony 500w for $50 and my freind a kenwood 600w for $60.
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    Registered User boosted scoob's Avatar
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    Quote Originally Posted by hybrid gti 2
    does not sound like it would work to have two amps power one speaker. likly would blow one of the amps. but I could be totally wrong on that. but sound quality would likly suffer if it was possible. if it was me time to shop ebay and find a biger amp. I got a sony 500w for $50 and my freind a kenwood 600w for $60.
    Thanks for your reply, but the size of the amp is not the problem here. I'm more worried about interference from having 2 amplifiers hooked up to the same speaker. I would need 2 separate amps cause I have to convert the phone kit's speaker output to RCA and then pass the RCAs to the amp, but the RCA inputs on my 400W are already taken up, that's why I need a 2nd amp.

    I know there's some electrical engineer-type peoples out there like myself. Except I can't figure this one out. Care to help out? Thanks.
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    no, you definitely don't want two amps connected to the same set of speakers... bad idea. Basically you're connecting the outputs of two amps together.

    What you really want is a way to hook up two sets of RCA's to a single amplifier (considering that you're getting a line out converter for your phone).

    How much of an engineering background do you have? With a little technicaly knowhow, it's be pretty easy to rig up a simple circuit to "switch" the rca inputs. Basically, build a project box with two pairs of inputs, one output. Then, figure out which line from your phone triggers the mute on your radio. Finally, design a small circuit to use this remote mute signal as the switch. Shouldn't be hard to do with a few basic components/gates.

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    Registered User Th3Franz's Avatar
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    I've only heard of people hooking up multiple amps to a single multi-coil sub-woofer. I don't think it would work for regular speakers.
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    Registered User boosted scoob's Avatar
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    Quote Originally Posted by tad_02Wgn
    no, you definitely don't want two amps connected to the same set of speakers... bad idea. Basically you're connecting the outputs of two amps together.

    What you really want is a way to hook up two sets of RCA's to a single amplifier (considering that you're getting a line out converter for your phone).

    How much of an engineering background do you have? With a little technicaly knowhow, it's be pretty easy to rig up a simple circuit to "switch" the rca inputs. Basically, build a project box with two pairs of inputs, one output. Then, figure out which line from your phone triggers the mute on your radio. Finally, design a small circuit to use this remote mute signal as the switch. Shouldn't be hard to do with a few basic components/gates.
    You are absolutely right. The more I thought about hooking 2 amps up to the same speaker, the more crazy that sounded to me. Then I thought about it more and came up with exactly what you said. Using a line-level converter, the output from that would have to go into a 2-channel mixer and then into the amplifier. This would absolutely work. Only downside is the cost of this little project. The mixer would run $40 and the converter another $15. Oh well, to me it's worth it. Time for Ebay. Thanks for your replies.
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    The switch will not work... longterm. You can only use one amp if you want to do it right.

    Here's why... The two amps will conflict, and current will travel down the wire of the inactive amp, most likely resulting in a fried output circuit, or if both stay on, a blown speaker. Instead of switching between the amps, get a X-over, EQ or a plain line driver with 2 inputs. It will allow you to switch between the sources, improve overall sound, and since they will most likely be active (meaning that they're powered), raise the Voltage on the signal, alleviating the low volume problem you're having with the phone kit.
    Those fools, EVO vs. STi??? That's like comparing ....wait a minute...there's no comparison. The Suby's still working!!! The evo...well... I hope he got the extended warranty.

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    Quote Originally Posted by ej20fan
    The switch will not work... longterm. You can only use one amp if you want to do it right.

    Here's why... The two amps will conflict, and current will travel down the wire of the inactive amp, most likely resulting in a fried output circuit, or if both stay on, a blown speaker. Instead of switching between the amps, get a X-over, EQ or a plain line driver with 2 inputs. It will allow you to switch between the sources, improve overall sound, and since they will most likely be active (meaning that they're powered), raise the Voltage on the signal, alleviating the low volume problem you're having with the phone kit.
    you are correct that a switch may cause problems longterm between TWO amps... but i was talking about switching the two inputs to a SINGLE amp... however you do this. I haven't seen any crossovers or eqs that allow you to switch between two inputs, if you could post a link to one that may be helpful - would certainly save some fab time for him.

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    Registered User boosted scoob's Avatar
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    ok basically the only way I can see to do this project cost-effectively and easily is to use a line-level converter (around $12 shipped from Ebay) in conjunction with a 2 channel stereo mixer ($35 shipped from Ebay) -- gotta love Ebay!

    The ART PowerMix II mixer inputs a mono signal through an unbal. 1/4" phono plug. This works since the phone kit is mono anyway. All I would have to buy extra is a stereo RCA to 1/4" mono adapter from Radio Shack. Then the mixer's 2nd channel inputs stereo RCA (coming from my headunit). The output is stereo-mixed channel 1 and 2 into my amplifier's front RCA inputs. Also, I can hardwire the mixer, which is supposed to be for DJs, into the electrical system since it uses 12V DC.

    Now I just have to buy the ish.
    02 WRX - XS Power header/UP/TBE, XS Power FMIC, MBC@15psi, Ported TD04L, Perrin shortram, Alum Radiator - 13.35@101
    05 Mini Cooper S - Bone stock
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