2 amps wiring
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=31527
Printed Date: April 27, 2024 at 9:53 AM
Topic: 2 amps wiring
Posted By: toyota_4runner
Subject: 2 amps wiring
Date Posted: May 03, 2004 at 2:07 PM
I had a question of choosing between 2 amps ( one 4 channel and 2 sub channel) OR one 6 channel amp. Well, from the replies it seems both will work for me and I am now trying to make the system economical. SInce I already have one 2 channel MTX thunder 275x amp, I will look for a 4 channel amp (40 or 50 rms X4, suggestions, pm regarding used amp sale welcome) Head Unit: Kenwood KDC-V7022 which has 2 amp preouts. NO sub preouts. One of the set of Rca says front and other rear. I have a simple question: How do I connect the two amps? Do I take one pair of RCA s into the MTX 275X for subwoofers and the other pair into the 4channel? Or does a 4 channel amp need to be connected to both pairs?
Replies:
Posted By: audiokid1
Date Posted: May 03, 2004 at 2:18 PM
You can use y-adapters to connect the 4 channel to the front preout but you will not have fade front to rear capability with your mids and highs. Or you may be able to use the pass thru outputs on the 4 channel (If it has them) and run a pair of interconnects from that to the sub amplifier.
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Posted By: toyota_4runner
Date Posted: May 03, 2004 at 2:35 PM
That also reminds me, one of the pair of RCA's says "no fade" on the RCA cable. Also can you suggest some 4 channel amps which have this feature (pass through outputs to connect to the sub amp)?
Posted By: audiokid1
Date Posted: May 03, 2004 at 2:43 PM
does the rca say no fade or non fading
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Posted By: toyota_4runner
Date Posted: May 03, 2004 at 3:43 PM
oh yes non fading. sorry didn't write the right phrase. What does it mean? Its hard to believe it wont allow me to fade if I use an amp!
Posted By: kgerry
Date Posted: May 03, 2004 at 6:15 PM
a non-fading pre-out is separate from the front and rear pre-outs...so that regardless of whether you fade all the way to the front or to the rear, you will still have full signal thru this set of pre-outs.... perfect for something like a sub application and some amps do indeed have a slave preout to be used with a second sub amp...i cant think of any specific brand off the top of my head...but shop around and you'll find them ------------- Kevin Gerry
Certified Electronics Technician
MECP First Class Installer
Owner/Installer
Classic Car Audio
since 1979
Posted By: toyota_4runner
Date Posted: May 05, 2004 at 10:14 AM
I rechecked the outputs on my KDC-V7022 ( you can see the wiring on page 40 of manual (same manual for KDC-MP822) on this website:
https://www.kenwoodusa.com/support/manual.jsp?divisionId=3&productid=2500
So I have only one preout (front) and one non fading preout. But I dont want to use the Y adapters as audiokid suggested since I would like to have control for fading.
My question is Can I directly connect the F and R speaker wires from the harness into the amplifier? (aren't they call "Hi-Level" connections on the amplifier?)
I was reading a manual on an amp and it said you shd connect RCA if available and if not use hi-level. Whats wrong or bad about using the speaker connections directly?
Thanks again
toyota_4runner
Posted By: DYohn
Date Posted: May 05, 2004 at 10:49 AM
Yes, you can use the speaker level outputs from your head to drive the high-level inputs of your amplifier. The only problem with doing this is the signal tends to be noisier and setting input gain is harder. In general, a "non-fading" pre-out is designed for use with a subwoofer amp. Another option to consider if you need more pre-amp level outputs than your head provides is to use a good crossover or EQ or line driver unit like an Audio Control Three.1. This will allow you to split and amplify your single pre-amp out into several signals for amplifiers and give you some envelope modeling capability as well. ------------- Support the12volt.com
Posted By: toyota_4runner
Date Posted: May 05, 2004 at 2:27 PM
I am posting the question again... The salesman at tweeter really ripped me off by false information, firstly they said the KDC-V7022 played MP3s and it does not (someone here also said it played mp3 but it actually doesnot) and he also said it had 3 preamps and it has only 2! I bough it because it was a good deal (open box) and am in trouble now. Anyways now instead of spendin gmoney in trying to get extra preamps I guess I will connect only front speakers and the subs and connect the rear coax speakers directly through the HU. ALso, I just bought the following (used) component speaker system for the front MB Quart QM 215.03 CX Crossovers MB Quart QTC 25 tweeters ( one website says it is 90W RMS) MB Quart QM 130 speakers 5.25" (130mm) Midrange My subs are 8 inch 8 ohm Rockford Fosgate which I d like to bridge to 4 ohms My rear speakers are Boston Rally RM6 coaxials, Also now since the front speakers have higer RMS rating and rear have less, it migh tbe a good idea to connect only the front to the amp. What do you guys think?? My options: 1. I am thinking of getting a 4 channel amp and using two channels for front components and one channel for the subs bridged. OR, do they make 2 channel amps with extra channel for subs which will allow me to connect both front speakers and the subs? 2. I have this MTX thunder 275X 2 channel amp which I was going to use for the subs. Now can I connect both speakers and the subs in parallel? 3. OR shd I get another 2 channel amp for the front and have TWO 2-channel amps one for the MB quarts and one for the subs? Thanks again!
Posted By: customsuburb
Date Posted: May 05, 2004 at 3:21 PM
Above is a reccomened system diagram. 1. Use a good 4 channel amp for the front components and subs (like this Rockford Fosgate one). 2. No, I would use this amp for the boston acoustics speakers going in the rear.
Posted By: DYohn
Date Posted: May 05, 2004 at 3:28 PM
Great suggestion above. (I deleted the strange formatted post, by the way.) ------------- Support the12volt.com
Posted By: customsuburb
Date Posted: May 05, 2004 at 3:31 PM
sorry that diagram i posted is wrong. I meant for the sub output on the 3xs to go to the 4 channel amp instead of the mtx amp you currently have and the rear output from the 3xs to go to your mtx amp.
Posted By: toyota_4runner
Date Posted: May 05, 2004 at 3:32 PM
Vow! Thanks a ton! Now as I said earlier one of the two preouts I have is non fading (which now I understand is good for subs etc which u dont need to fade) SO can I still use this Audio COntrol 3is and still be able to fade between the front MB quarts and rear Boston RM6 coaxials?
Posted By: customsuburb
Date Posted: May 05, 2004 at 3:48 PM
I'm pretty sure that you can switch the rear preamp output on your deck from fading to non-fading.
Posted By: toyota_4runner
Date Posted: May 05, 2004 at 11:29 PM
Yes the HU does have option of chanign from non fading to fading, just checked the manual.
Question: the rating on the subs is 150 RMS each and that of the MB quart is 80 RMS .please correct me if I am wrong, I got this info from
https://www.mbquart.com/2003/en_US/products/prod_detail.asp?isArchive=true&cat=&series=q%20series&strt=1&model=QTC+25
and you suggested a 50W X4 amp. Wouldn't the speakers perform better if I use a higher RMS amp?
Posted By: toyota_4runner
Date Posted: May 07, 2004 at 10:13 AM
How about this set up? I was trying to eliminate the cost of Audio controller 3xs suggested by customsuburb and also I hooked up the 275X to the subs, bridged at 4 ohm to get 150 W Please comment/suggest. 
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