Replace sub or add amp?

[Tom Brokaw 10+ year member]

Hello,

I have an older RF 75.2 Punch. I asked for, and got, a DVC Infinity 1262W for Christmas. Problem is, I goofed. I assumed DVC can do 2, 4, or 8 ohms, but of course it can only do 2 or 8. The Punch is only stable bridged to 4, so I wired the speaker in series and am running it at 8 ohms.

I calculate that means I'm pushing 75 watts (150W bridged @ 4ohms/2). It's not loud enough.

Now, it IS stable at 2ohms when run in stereo. So it makes sense to me that I could run my full range speakers in parallel off of this amp: (2) 4ohm speakers per channel. They are currently being run off the head unit.

Here's my question, and it may come down to opinion, and that's fine, that's what I'm looking for.

Would you get a single mono amp to run the sub, and use the Punch to power the full range speakers, OR, replace the sub with a 4-ohm unit and otherwise leave things as they are?

With regards to the former, can someone please verify my calculation for the full range speakers:

Per channel: 75 Watts into two speakers = 37.5W each speaker. Is that correct? Because they're rated at 30. I am not going to have it full blast most of the time so if it's an 8W difference that's fine, but if it's a 45 watt difference I think that's a bad idea.

Thanks for your input.

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[DoesDad 10+ year member]

Use the punch with your mids and get a small mono amp for the sub. If you look on Craigslist you should be able to get one cheap.

 

[akheathen Premium Member]

just which punch model. a pic would help. it might/likely is underrated, and could actually be 300+@ 2ohm bridged

 

[DoesDad 10+ year member]

just which punch model. a pic would help. it might/likely is underrated, and could actually be 300+@ 2ohm bridged

True...

 

[Tom Brokaw 10+ year member]

Thanks for the replies. so running the rf onto the fullranges won't blow them?

It's a Punch 75.2; I've seen it referred to as the "black and grind" model. Has an X-Card crossover. Manual says it's stable at 4 ohms bridged.

Edit: here's a pic of the same model.

http://s579.photobucket.com/albums/ss234/sinuhe97/Amps%2003_01/?action=view&current=IMG_1711.jpg&newest=1&call=1

 

[akheathen Premium Member]

i have one on the bench in *****-anna grey. @12.5vdc on my supply, the rail voltages are pretty high on it, and should be capable of 2x190@4ohm stereo max, 406@8ohm bridged max. i'll have to put a tone through it if i get it fixed and see what it really puts out under load.

 

[audiobaun 5,000+ posts]

My opinion,that amp is not a real powerhouse for a sub, and @4ohms bridged even.I would put that amp on my mids n highs,and find or i can even sell you a good old school 2ch that can be bridged @2ohms mono, and bang that sub pretty good.If you want 4ohms, I have a few also, but Id get to the 2ohm load on the sub.I have an Autotek BTS 7050 Zed made 2ch that will bang that sub pretty hard @2ohms, or I have an Orion Hott Settup X-Bones 300 that will bang that sub pretty good also.Pm me if any interest.Yet, Put that RF on the front , and find a 2ohm stable bridged amp/mono,and get that sub banging.You can find some good old school amps,and pretty decent new amps for anywhere from $100 up for a decent amp in my opinion.

 

[Tom Brokaw 10+ year member]

So that's two votes to migrate the RF to non-sub use and add a sub-only amp.

It looks like a few people around the web ran the same amp bridged at 2 ohms - I'm kind of tempted just to try that, as that's a lot simpler than figuring out where to mount a second amp and how to wire it. Not cheaper if I burn up this one though.

Anyone have any input on the question regarding wattage on the full range speakers?

Thanks again for your input.

 

[bigblacksnake 10+ year member]

i know that some of those fosgates can do 2 ohm loads bridged no problem, especially the older ones.