Wednesday, March 01, 2006 - 09:59 pm, by: Adam Sanders(Abz)
Hi
Is there anyone who could explain to me how i woull go about adding 1 or 2 aftermarket amps to my existing system so I still retian full use of my stock system?
Thursday, March 02, 2006 - 09:01 am, by: Denham Melder(Inasnt)
I dont think the stock headunit has any preouts to attach amps. U could always try get some amps which use speaker inputs instead of rca inputs to transfer the signal.
Ideally you would want to remove the stock head unit but find another head unit where you can reuse the stock 6 stacker.
Thursday, March 02, 2006 - 01:47 pm, by: Mark Paddick(Sparks)
Of course the stock head unit has pre-outs, otherwise how do the factory amps work? They aren't nice cinvenient RCA sockets but the wiring from head unit to amps is obviously at per-amp level. You need to find a wiring diagram and identify the input wires to the factory amp and also the speaker wires out of it as well as Batt and Acc. Then just substitute aftermarket amp for factory amp. The aftermarket amp won't have the 'mute' function but everything else is the same. OR you could just get the upgrade Nakamichi amp from the US Lexus LS400 and plug it in. Be careful though because there are several different versions of the LS 400, only one of them is the same as the Celsior wiring-wise. The upgrade amps are 4 x 100WRMS but the Yanks know that they are good so they aren't cheap. The convenience of straight plug-in and factory mounts is worth it. You can get the head unit too for correct FM band for here, AM band is wrong though. Head units are cheap as there is no difference from standard to upgrade (apart from front panel logo) and the Yanks know that too. There's no market for them there.
Saturday, March 04, 2006 - 08:27 pm, by: Mark Paddick(Sparks)
Yeah and what relevance is that? And 4V with reference to what? The standard pre-amp output is and has been for the last fifty years or more OVU (1.23 voltsP-P @ 1kHz into a 600 ohm load and it became the standard in 1939 and has not changed since). Most pre-amps provide a rated output of around 1V P-P into 47k or thereabouts which is essentially the same thing. There are various other standards used, the most common being dBV (followed by dBm and dBu). Telecommunications tend to use dBm where the reference is 1mW into 600 ohms. Audio is generally dBV where the reference is 1V and this is where the standard pre-amp level comes from. The reference frequency is usually 1kHz but Telecoms again use a different frequency of 600Hz (considered to be the mid point of Human vocal range). There is absolutely no benefit in having an output level from the pre-amp any higher unless the main amp is such low gain that it doesn't warrant being called a voltage amplifier at all. I have yet to see a commercial amplifier of such low gain. A higher pre-amp voltage only serves to overload the power amp input. Many higher quality pre-amps will quote a headroom figure which is an indication of instantaneous overload levels before the onset of significant distortion (and if actual distortion levels and frequencies are not specified the figure is meaningless) and this will be in the 2V to 10V region. The actual pre-amp level for a standard input is still 1V. And anyway the question was how to hook up a standard head unit to an aftermarket amp which I think was answered. I can assure you that Toyota head units are capable of considerably more than 1 Volt P-P output into the load presented by most amplifiers. The IC's used in the pre-amp output stage are capable of swinging to within 50mV of the supply rails so maximum output is in the region of +/- 6 Volts or 12 Volts P-P into the average 50k ohm load.
Adam if you need more info on the factory wiring I may be able to help.
Monday, March 06, 2006 - 10:35 pm, by: Adam Sanders(Abz)
I understand that much lol, also i know you need to find the wires running from the deck and change them from low level to hi or whatever and wire to rca or get an amp with those other plugs but i am really looking for someone to do it professionally i guess
Tuesday, March 07, 2006 - 12:23 am, by: Mark Paddick(Sparks)
NO. The wires from the deck to the amp are pre-amp level if it is the factory deck so it is just a matter of fitting RCAs to them. The '90s Toyotas are quite advanced with separate power amps in the boot so fitting an aftermarket amp is much easier than some other cars. The factory sub can be a worry though. Burwood is not THAT far away from Queanbeyan......
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