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RF amp installation question

6K views 21 replies 8 participants last post by  h-donut 
#1 ·
I've searched until I'm blind, but I can't find anything indicating how to connect the HK head unit to the RF amp. I would like to use the pre-out inputs that came with the amp, but it's not a requirement. I saw where one of the aftermarket companies make a connector that plugs in the back of the HK unit, but does it have pre-out plugs or would I still have to cut/splice?

Also, on the PBR300X2, did you run power all the way from the battery to the amp? I see that the specs for power only indicate a 10 ga wire is required.

All assistance is appreciated!
 
#2 ·
Hi,a stock HK unit does not have pre-amp outputs. With a stock radio you need to use the high level inputs on the RF amp. Yes, you should run the amp pwr to the battery.

There is a company, Iron Cross Audio, that will install pre-amp outputs in your HK. Some on this forum have done that with apparently good results. I'm considering going that route myself.
 
#3 ·
a line converter would do the job, takes the speakers signal and converts it to RCA.



the amp does it internally also, but you have to
a. spice the RF rca cable
b. make sure the highest voltage on each speaker is positive

the HK radios have a tendency to be wired backwards (or out of phase) on the right channel at least mine were, twice.

if you do spice the RF RCA cable try and leave enough room to spice later if you change you mind, also staggering the spices will reduce cross talk, do the two positive spices outermost and two negative one inner most.

I bought the massive audio line converter, never used it, $20 and it's yours.

the one pictured above is $10

power, I went to the battery and grounded to the fairing sub frame.

shorter distance for ground.

you could check also, the 4 pin molex motherboard connectors, I believe might plug in to the RF and then you could leave your RCA cables in the box.

biggest thing with the stock radio is too much voltage, so line conversion or
iron cross conversion helpful.

the RF will take your speaker outs and deal with it, but make sure the voltage paths make sense.

hope that helps
 
#6 ·
the voltage levels from the speaker leads, with a meter

after my first radio died, checked the wiring with a meter, the 6.5v positive lead, had shot up to 12v, on reverse side, radio lost it's resistor internally, would be my assumption, radio died soon after, had dealer replace the radio, went back down to 6.5v, but still on the opposite wire, the green with stripe should be the ground side, according to book and the connector on that wire

so, I'm just saying that make sure your amp is getting good target numbers.

4.5v would be best, it will accept the 6.5v input but it makes the amp work harder than it needs to, sound wise it make it muddier.

amp will accept 2v also, but requires remote wire.

bottom line is, running the stock radio without doing a line converter, checking with a meter and trimming the voltage, you run a larger risk of damaging head unit, because the RF will reject that extra voltage and send it back to the radio. make the internal circuits work harder.

the radio doesn't have overload protection like the amp.

I know I'm not explaining it well, but after having several people report on their stock radios dying, and what happened, that is my theory on why, out of phase wiring on the right side of the radio.

I still have my stock radio, debating on whether or not to tear it open and do the RCA mod myself. Would have to look at the PCB first.
 
#7 ·
OK, I will find a line convertor. I think I pulled one out of my current commuter car, so I may just have one laying around the shop somewhere. I'm pretty sure the 00 gauge wire will be a little over the top for power, so the 8 gauge will git-r-dun!

Thanks for the replies guys!
 
#8 ·
If I get an adjustable LOC, how do I measure voltage of the output leads?

I've read that 4.5 volts is optimal, but the higher the value, the less work the amp has to do. I also read that the HK unit puts out about 9 volts.

I am not interested in blowing the head unit or the amp.
 
#9 ·
you are close in your numbers, stock head unit pushes a 6.5v signal to the speakers

I bought a volt meter at harbor freight and some alligator clips, test leads

not a fluke meter by any stretch of the imagination, but give a good rough idea of what is going on for the price of a 9v battery.

also checks ohm

4.5v is your target voltage, not sure why but it just is, most better radios state 4v RCA's as a feature over 2v outputs.

4.5v best
2v good, but requires remote wire for amp to turn on
6.5v stock voltage, too hot, it will work, but for how long is the question?
 
#10 ·
Hdonut is spot on. I run two 300X2's and recently switched over to the 8 gauge from the 10 gauge that came with the Yaffe kits. There is a night and day difference since swithing to the lower gauge power wire. Do it right the first time by getting spending the extra money and get good quality wire. Take it from a guy who tried saving a few bucks only to have spent twice as much in the end.

I plan on sending my stock radio out to Iron Cross Audio to have them install the preouts this winter. I think this option verses the low line leverl adapter is the better option. I did have a sony radio installed but could not get the levels I was looking for.

Chris
 
#11 ·
I got the speakers and amp installed finally. I found some 9 gauge wire in some stuff my son and I used on his car so I used that for power. I read the manual for the PBR300X2 and followed their instructions for connecting the speaker wires to the amp instead of using LOCs. I mistakenly bought the MM651UM speakers so I relocated the tweeter to to the small side of the factory speaker adapter. I also had to disassemble and remove some of the back of the speaker housing so that it would not rub on the fairing. I really like the fact that it looks bone stock too.

All in all, it performs so much better than stock. I am pleased with the outcome and now I can turn it up loud enough to hear it over my Drago clearly.

Thanks for all the assistance guys!
 
#15 ·
I wouldn't mind seeing your relocation mod.
I didn't take any pics, but I used a 1.75" hole saw and centered it on the small side of the speaker mount, cutting really slow and deliberate. I used a cutter that had a really short drill on it. It wouldn't take much for someone not paying attention to destroy the speaker mount.

I wrapped the tweeter with two sided tape and installed it in the tweeter cup. I then screwed the tweeter cup over the hole I cut. I think it's kind of "jerry rigged", but it works like a champ.
 
#13 ·
So h-donut, I just ordered the line converter, do I still need to meter the speaker wires to see if they have the right positive and neg from the factory? Getting ready to install your bracket and my pbr300X2 amp.
 
#14 ·
I'd get a meter in there, if it's a bare wire anyways.

please let us know what you find


the PBR300x2 did state some software improvements in March 2012

an earlier post in elf amp days stated better to have the line converter fail than an amp or factory radio.

once the line converter is on there, I'd check the outputs, yes

not sure about the remote wire, though, if you need one, I think you do.

the turn on voltage dial can be swept from 4-6v

sometimes it doesn't work, as with my DSX-310, is supposed to have 4v output RCA's, so switiching from the MS60 (2v) to the 310, I should have had to cut or remove the remote wire, but I still needed it.

no I didn't measure the RCA outputs, but I might next time if I remember.

with the line converter I would, since it has voltage attenuator, you can
also go back and tweak by ear, like a biassing a preamp, just don't get too fancy. your best setting will be shades away from 4.5v if I'm understanding
the concept correctly.

basically with that amp, it's that amps choice whether it needs the remote wire, up to a point.

sounds like you have all your ducks in a row, hope everything goes smoothly for you.
 
#16 ·
Thought I would post up a picture of the KnuKonceptz power and speaker wiring I bought on eBay. The shocker to me is how BIG this stuff is so I put a ruler in the pic for some perspective.

Got the same power distribution block h-donut used ($9). Now I just need to figure out how much surgery is required to get the ring terminals to fit. Nice thing about the ring terminals ($5) is they use a set screw to hold the 4 gauge power cable ($3/ft) so you don't need an expensive crimp tool.

The 12 gauge twisted pair speaker cable ($.75/ft) is also a much bigger diameter cable than I expected but the stuff is beautiful. If I have sound problems after this install, I don't think it will be for under-engineering the cable specs.

 

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#17 ·
for solder joints I was doing two flat V's, about 3/16", with heat shrink, then a little extra vinyl tape, for stuff that poked through, or looked liked it wanted to, tryed to stagger them.

yeah, had to trim top of the battery box quite a bit.

to get the oversized cable to fit, expecially at the amp side, used scissors, exposed wire, did a flower, and trimmed sides a strand or two until it was just the right size

I had zero extra power or ground cable when I was done, or I'd take a picture.
 
#20 ·
dumb question... but why the power dist box? you running more than 1 amp?
Yep, I'm running two amps.

Also what size fuses are you guys running?
I ordered 30 amp fuses but I have no idea what I'm doing. I just watch h-donut and do what he does ;)
 
#21 ·
dmize, when I was doing one amp, I had an inline closer to the FH-44 you listed

single 50 amp fuse, waterproof, taped the ends w/vinyl

that dual block came with 4 fuses, so I requested 40 amp and 30 amp, I'm running the 40 amp, amp spec is 30 amp. I will try the 30 amp fuses eventually, maybe.

a local installer told me you could twist two 8 gauge wires together, and reuse the fuse holder, but you know how that goes.

I've never blown a fuse so far on the bike due to the rockford amps.

those amps drain the battery quicker with two of them, but not so bad.

saddlebag lids pull a bunch of bass, which pull a bunch of power.

maybe not worth mentioning, but had a crackle in right output, second amp, when I was installing and adjusting fade, first time running it, dialectic grease in the amp output 4 plug connector, fixed it.
 
#22 ·
also throwing it out there, nolox can be used on connections if regular dielectric grease is too slippery, and it is.

I try and coat everything with a little of both, stops oxides from forming later.

I did a side mount ring terminal, for the 4 gauge wire, as stated earlier getting extra wires in there is tight, took top half a 1 1/2" pipe clamp for grounding to plumbing, bent and machine filed until it worked, broke 2 before getting the 1 right. then trimmed the top lid of the battery cover that holds the ECM on the front side corners, smoothed the edges, then insulated the 4 ga connector I had just made with vinyl wrap.

I still am planning on sealing the end caps of the amps with black RTV.

I take a week or two off from projects sometimes to gain perspective.
 
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