i just got and older RF power punch amp and i want to know how to get my subs to 1ohm.
thanx

 

The only way to get a 1 ohm load with single coils is if they were 2 ohm speakers and wire them in parallel. If they are 4 ohms each, the best you can do is 2 ohms in parallel.

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-Justin-
T-Top '86 5.0L LG4 700R4 WS6 Now Bilstein equipped!
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The F-body Model Kit Pictoral Archive (updated 9/18/00)

There can be only one!!

 

Four 4 ohm speakers in parallel would be 1 ohm. Net resistance in parallel is 1 / (1/R1 + 1/R2 + 1/R3.....)

Tim

 

Just out of curiosity, why does the impedance have to be 1 ohm?

Tim

 

Thats true tim, but he wanted to use just 2 speakers.

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-Justin-
T-Top '86 5.0L LG4 700R4 WS6 Now Bilstein equipped!
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My '86 Firebird Homepage
The F-body Model Kit Pictoral Archive (updated 9/18/00)

There can be only one!!

 

just like justin said, with 2 speakers rated at 4 ohms u cannot acheive one ohm. i have the punch 50.1 and 50.2, i run them both at 1 ohm but im also am gonna use Punch DVC woofers. if it is a power series rockford amp, give it 2 ohms, it will drive those subs just fine.

daniel

 

Actually, if for some reason, your amplifier was matched to 1 ohm, and all you had were two 4 ohm subs, and you had to have a net 1 ohm impedance, you could put the two subs in parallel with a 2 ohm dummy load resistor (rated at 1/2 the wattage of the amp), however, the maximum power dissipated in each speaker would only be 1/4 of the maximum power output of the amplifier - extremely inefficient - and the load resistors would get quite warm at high volume levels.......

Tim

 

Well, I can tell you this, nearly every rockford amp will overheat is your trying to run it at 1 ohm mono. What you can do to wire it up to save your amplifier would be this..

you have 4 terminals on the back of each speaker, one on each side, take the positive terminal on ONE side of the speaker to the terminal on the other side of the speaker.. Connect it to the negative terminal. You should now only have 2 terminals on the speaker..

Now get you speaker wire long enough to either go to the terminal on the box or to the amplifier. Connect the postive to the open positive terminal and the negative to the open negative terminal.

Repeat this process for your other speaker, this should set the amp at a 3.64ohm load. You really don't want to go any lower than this even with the older amps. The only one they have out now capable of doing this is the bd1000. Which is a mono block amp designed to run only 2 ohm mono, but with capabilities of running 1ohm mono for up to 12 hours.

 

actually shane,

he said he had an older rockford power series amps. they utilize a differnent power source than the "regular" punch style amps. becuase of that source (trans-nova i think) they are stable at 1 0hm, thats why they are sold as competition amps. The only two RF amps that can handle the 1 ohm load is the 50.1 and the 50.2. i know cuz i own both and its manual says its stable to 1 ohm

daniel

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86 camaro cpe(dont laugh)has 92z28 body kit with GTS covers, new red paint and a killer stereo. 2 amps, 8 speakers, disc changer, custom install with subs coming by the end of the summer. sawpped (or in the process of) 305lg4 for brand new 350. TES headers, flowmaster cat back, performer manifold, TCI converter, jet chip, kn with dual snorkel cleaner. and she still passed the sniffer!

"Cal Poly SLO is the shi#"

 

I've sold Rockford Fosgate for 6 years now, it IS NOT STABLE AT 1 OHM MONO! Ahem.. it's stable at 1ohm stereo which is completly different, set your car on fire when the amp burns up, i'll laugh..

 

Stinger made a device that could be adjusted to make the amp think that there was a lower ohm impedance. It kind of goes along the line of Tim's idea of wiring in a resistor. The Stinger (cant remember what they called it) was tested in car audio mag a few years back and was found to cause harmful spikes at different volumes and frequences and could damage a speaker or amp. Just something to think about before anyone tries wiring in a resistor, but at least a resistor wont cause a phase change in AC

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-Justin-
T-Top '86 5.0L LG4 700R4 WS6 Now Bilstein equipped!
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My '86 Firebird Homepage
The F-body Model Kit Pictoral Archive (updated 9/18/00)

There can be only one!!

[This message has been edited by Justins86bird (edited November 23, 2000).]

 

The impedance matching device you may be referring to is called an autoformer - it is a transformer configured to match one impedance to another, but does not provide isolation, as one leg of the the primary & secondary windings are connected together. There are generally multiple taps that allow selection of the impedance being used on one side, while the impedance seen on the other side remains constant. They are used in multiple speaker systems, where the amp is limited to a minimum impedance value that is greater than the parallel combination of the speakers used in the distribution. There are variable autoformers, too, which keep a constant impedance looking into the source, while allowing the output level driving the load to be varied.

I'm still curious as to why 85camaro wanted to drop the impedance to 1 ohm, rather than just driving the two 4 ohm subs in parallel - any ideas?

Tim

 

If the amp was able to run at 1ohm mono, you would get more power to the subs. I've run a single 10" DVC sub in a 92 camaro and it hammered. I can't see why you would want to DVC's to really be that loud, your just going to loose your hearing. I've installed now for 7 years and I really don't like big subs anymore. I only have 2 8" DVC's.

 

Shiner,
Please note, the question was about 2 single voicecoil subs. They wouldn't have 2 sets of terminals. Even if they were, the scheme you have described would be 2 ohm.

 

I was just looking at the topic where it said 2 svc's.. looking at where it would be easy to hit the s key instead of the d key.. If they are single voice coils then run it 2 ohm mono.. just take both of the speakers directly to the + and - of the amp.. I really wounldn't recommend running 1 ohm even with an accumatch.

 

What the audio shop where i got my Earthquake 2ch amp from said was that if i take my 2 4-ohm subs and wire them in parallel to the amp in bridged mode, that would be one ohm load. Are they wrong?

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~Sp33d~
(sold)1989 2.8l 5-speed RedBird w/ flowmaster, cold air intake, TRW cam. Audio system includes-Cadence component plate 4x6's/Cadence 3way 6x9's,300watt amp to front speakers/400watt to Blaupunkt DVC 12" sub.

 

Yes they are wrong. Use the product over sum formula for figuring out two impedances in parallel. 4*4/4+4=2 ohms.

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-Justin-
T-Top '86 5.0L LG4 700R4 WS6 Now Bilstein equipped!
T-Top '92 5.0L TBI 700R4
My '86 Firebird Homepage
The F-body Model Kit Pictoral Archive (updated 9/18/00)

There can be only one!!

[This message has been edited by Justins86bird (edited November 25, 2000).]

 

I have heard a lot of stereo shops say that when you run an amp in bridged mode that it drops the Ohms in half. I've gotten so tired of hearing how much these "profesinals" know about Ohms law. The truth to the whole bridged theory is that no matter how the amp is set up to run, it still only sees the impedance that the speaker, or speakers build. The resistance that is measured in Ohms, is created by the speakers, not the amp. Also, just because an amp says "1 Ohm stable" doesn't mean that you have to go as low as you can. The lower the resistance, the higher the THD (total harmonic distortion) will be. That means lower sound quality, even from a Rockford.

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'82 Firebird, dead stock, 9 bolt disc rear, over 200,000 miles and still going strong, more to come...