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Am I shorting myself power? Long time bass head out of practice

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Discussion Starter · #1 · (Edited)
2012 Grand Cherokee Laredo with factory great sounding amplified 10-speaker setup bought for my son. Wanted more bass via high output RF converter…
( Gen-Z’ers please take no offense with this next description of where I’m at presently. )
Have and kept up with my 1998 Chrome Power 500.2 RF amp with card etc. Bc she was a monster way back when. Brought to local trusted install shop here in Charleston SC to power a wanted single sub. All employees 34 yo or younger and unfamiliar with this amp. Was sold a new RF P3D4-12 in trade in “tuned” Amazon vented box to run power off of from my amp.
Setup sounds great but my only qualm is I possibly got less sub needed than what amp is capable of; sub is 4ohm DVC and wired into one channel per appearance. Gain at nil; Bass EQ at nil.
Is this ideal setup for anyone with some working knowledge of what this amp is capable of? Pics attached.
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A93F2514-1FC7-43A6-A8D9-069CE18EFBF6.jpeg
 

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They installed that with only one channel driven? That is asking to destroy your amp.

It should be properly bridged. Those dudes are twits.

Also, that ported box is NOT designed for that sub, unless it just HAPPENS to meet RF's exact spec. Looks prefab to me.

You have a copy of the RF amp manual? Make sure "bridged" is bridged.

I'd pop the speaker out, and be certain those guys actually wired both coils, too.

That is one of the BEST Rockford amps made, and were it mine, I would run each VC to one channel, but send the amp a summed mono signal. You're still getting PLENTY of wattage @ 4ohms stereo from that sexy beast.
Where are the end caps??? Did you take off for photos? Did they leave off?

I'm willing to bet if you enter the T/S parameters for that speaker, it's going to call for a different sized port and air space. (I'm sure the RF specs are posted on their site. The specs for that prefab box should be available online too.


Yeesh.
 

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When I say "best" RF amps...I mean...that is the OG Air Jordan of RF amps...The pre-lip-job Meg Ryan of sexy amps...The Mike Tyson of 1998 amps power wise.
So someone is going to lose an ear then?
 

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Discussion Starter · #7 ·
They installed that with only one channel driven? That is asking to destroy your amp.

It should be properly bridged. Those dudes are twits.

Also, that ported box is NOT designed for that sub, unless it just HAPPENS to meet RF's exact spec. Looks prefab to me.

You have a copy of the RF amp manual? Make sure "bridged" is bridged.

I'd pop the speaker out, and be certain those guys actually wired both coils, too.

That is one of the BEST Rockford amps made, and were it mine, I would run each VC to one channel, but send the amp a summed mono signal. You're still getting PLENTY of wattage @ 4ohms stereo from that sexy beast.
Where are the end caps??? Did you take off for photos? Did they leave off?

I'm willing to bet if you enter the T/S parameters for that speaker, it's going to call for a different sized port and air space. (I'm sure the RF specs are posted on their site. The specs for that prefab box should be available online too.


Yeesh.
I have both end caps and they left off post-install. I was under same suspicion hence my joining forum to validate my spidey-sense. It most certainly is a pre-fabbed box and I’m pretty certain I overpaid and had some younger well-meant installers set this up. I’ve kept this amp in pristine condition since I was a senior in high school (class of ‘99 to show my old age). Could you enlighten me on how the coils should be wired inside the box and then the config to the amp (assumably + to one channel/- to opposite of the two channels) to show bridged mono and what settings the other parameters should be showing? I really appreciate the help. It’s moreso the safety and new expense of my son driving this around vs the nostalgia and sentiment of this old rare classic stud amp I’ve always held onto in the hopes of sharing with the next generation of ears wanting to hear true reliable clean over rated power. I appreciate the info more than you know.
 

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Here’s a link to a very similar manual, it’s a 500a2 right? Those are just before my big car audio years but I did get to set up a few. I believe all the RF amps of that era were the outer speaker outputs to bridge.


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I would see if you can exchange the subwoofer for a D2 version since your amp can easily play into a 4ohm load bridged. You will want to wire the subwoofer inside the box so that the voice coils are in SERIES either way.

Crutchfield has a great simple overview on this. Here’s a screenshot to show a series connection. If you keep your D4 it’s the same wiring but you end up with 8ohms nominal at the amp. This is fine too and I agree with previous that you should bridge the amp vs running one channel.

303109


Link to Crutchfield wiring guide
 

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@DiamondFanatic I agree, The shop should have sold him a D2 sub so that amp could have been bridged to 4ohms mono. Being that they sold him a D4 sub he is kind of screwed because that amp is not 2ohm mono stable.
 
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Damping factor is cut in half bridged mono @ 4 vs running BOTH channels, summed mono, @ 4.

It's really apples/apples though, if you bridge that amp properly, and run the DVCs in series, the 8 ohms will present 4 ohms to the bridged amplifier. I'm still half asleep, but I'm pretty sure your pwr output will be same series/mono vs each ch to one coil.

My hunch is, the "Little Charleston Gang" wired your sub in parallel (2 ohms) which would present a 1 ohm mono load. The "brilliant" installer may have thought he did you a favor by using a single ch which can handle 2 ohms, but he's added lopsided strain to your amp. (I'd have him packing his tools up, were I his boss.)

Nothing wrong "per se" with prefabs, IF they were fabricated for a specific sub/match your sub's needs. Ported prefabs have been making me cry for over 25 yrs.

My other suggestion is a custom ported enclosure to EXACT specs for the tuning freq YOU want, not Zitty the salesman, or a sealed box of optimal volume.

Unfortunately, I'm easily 4 hrs from you up here in NC, or I'd gladly help in person.

To some audio is just a job. To me, audio is a drug. A necessity. A way to experience what the artist and producers intended for you to hear.

I carry a set of $19 JVC elcheapo headphones with me when auditioning systems. This way, if a person's system sounds like crap, rather than insult them with, "Yuck! This sounds like CRAP!" I ask them their favorite SQ song, and play it for them through the JVCs. (Muffs, NOT ear buds!! Ewww...not ear buds.)

This way, I can show the customer/friend etc. That a 19-dollar pair of sweatshop headphones sounds better than their $XXXX.00 system.

They typically hire me at that point to fix the mess or build their car.

As silly as it may sound, those JVCs are the benchmark for sub-$2500 system comparison. (Imaging wise.)

Anyway, definitely go either series VCs to bridged, or each VC to own channel, with a summed mono signal. I'm a huge fan of 8-ohms across a bridged 4ohm amp. You would gain approx THREE decibels halving that impedance in parallel (MAX, on paper!), yet you will cut Damping Factor in half, and double the heat produced by the amp. (And who wants to heat up their 98 Mike Tyson?)

Yeah - you can get "more watts" with half the impedance; you can get MORE CLEAN BASS with an 8ohm load across that amp/presenting 4 ohms mono load. Less heat. Less distortion, better sound.

Everyone is always obsessed with power power power. I'll take a 150 watt system set up correctly over a 2000w system that sounds like a PA system at the State Fair.
 

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Based on the way they did the install, if you pull the sub, it should be wired in parallel inside the box for a 2ohm load to the single amp channel. I can't stop looking at how tight that blue wire is...and for no reason.
 

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@DiamondFanatic I agree, The shop should have sold him a D2 sub so that amp could have been bridged to 4ohms mono. Being that they sold him a D4 sub he is kind of screwed because that amp is not 2ohm mono stable.
The sub does not bother me. It's the shadetree-quality install that kills me.

I guarantee that sub is PLENTY of sub with that amp, once it's in a proper box.

These new-school cats love getting as much wattage as possible. Wattage is only a small part of the entire system design.

That 500.2 is capable of making that sub its b**** at 8ohms/4 ohms across the amp.

The amp is almost 25 years old, and literally a Grail amp to Rockford geeks. Running it for MAX wattage adds unnecessary heat, and heat shortens the life of the components.
 

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Agree with the others, you want a d2 sub if you insist on using that amp.

That said, insisting on using that old amp is pointless too. You could have vastly improved the install with a modern class D mono that would have outperformed in in every way. Probably only been 200 to 300 bucks too. Old school gear is cool and all, but it's not really "better", per SE. I get wanting to give your son your old amp to have some kinda bonding thing, but the reality is this amp wasn't really the best tool for the job.

Personally, I'd just the Amp out for a modern mono amp, and maybe use this amp to drive a front stage if you insist on using it.
 

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Agree with the others, you want a d2 sub if you insist on using that amp.

That said, insisting on using that old amp is pointless too. You could have vastly improved the install with a modern class D mono that would have outperformed in in every way. Probably only been 200 to 300 bucks too. Old school gear is cool and all, but it's not really "better", per SE. I get wanting to give your son your old amp to have some kinda bonding thing, but the reality is this amp wasn't really the best tool for the job.

Personally, I'd just the Amp out for a modern mono amp, and maybe use this amp to drive a front stage if you insist on using it.
FYI, my PPI a600.2 outperforms by Mosconi Zero3. So i think you are not completely accurate here.
 

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Agree with the others, you want a d2 sub if you insist on using that amp.

That said, insisting on using that old amp is pointless too. You could have vastly improved the install with a modern class D mono that would have outperformed in in every way. Probably only been 200 to 300 bucks too. Old school gear is cool and all, but it's not really "better", per SE. I get wanting to give your son your old amp to have some kinda bonding thing, but the reality is this amp wasn't really the best tool for the job.

Personally, I'd just the Amp out for a modern mono amp, and maybe use this amp to drive a front stage if you insist on using it.

With all due respect...this is bull.

1) That Rockford could be used to power a small town

2) The OP is trying to pass-down his passion for the hobby to his son - what better way than to share an absolute HALL OF FAME amplifier with him?

3) As much as people LOVE class D for efficiency, A/B kicks it in the arse 9/10 times in SQ (until you get in to some $$$ amps)

I own some pretty good Class D stuff. NONE of it is in my SQ system.
 

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Discussion Starter · #19 ·
Hey thank you all for the knowledge and confidence that I’m onto something here. Here’s pic above for ref to how they have amp configuration run at present; who knows what position the X-card is in. Thanks also to the positive feedback of passing this hobby I enjoyed so much and stayed out of trouble (mostly; couple of Myrtle Beach noise ordinance wrist slaps cruising down the Blvd) to my stepson. We have baseball and now car audio in common and he’s a tech geek much smarter than myself.
As to the amplifier discussion of new digital vs old heavyweight, I’ve had both. And nostalgia alone, this amp I’ve got in his Jeep stays put and the sub/box/whatever revolves around it. It sounds clean as a whistle; I know it’s capable of MUCH more clean power than I’m seeing, and the fact it’s stood the test of time for 23 years without so much as a polish cloth tells the whole story ab how special this amp is and how ahead of the curve RF was with both clean underrated power and very clean SQ. She deserves to be played just like a watch deserves to be worn; no trailer queen here. Hopeful the GM/Owner of Custom Car Stereo Steve Cramer (43 yrs experience he told me when I first inquired ab a setup for the Jeep) remembers the proper configuration/tuning and will swap the subwoofer out for the correct model as he’s a certified RF dealer. Knowing his guys could’ve potentially ruined an heirloom of an amp and then easily convinced me it was due to condition or something on my end is worrisome.
Sidebar- the enclosure sold to me does not mimic exactly the recommendation from RF; Actual box measures 13.65”H 16”W 17.5”D (11” to chamber I believe based on pic)
RF says 14”H 25”W 12”D. Wondering if this needs to be addressed also for general principle.
Thank you all sincerely for getting me to this point! Cell below if anyone wants to text me info
Patrick Stewart
843-647-8807
 
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