jamieh

I have been advised I can but I would really appriciate your input.

I am purchasing a:-

JVC AVX33 Head Unit - RMS 20w per Ch - Load Impedance: 4 Ω (4 Ω to 8 Ω allowance)

JBL GTO6507c 6.5" 2 way components - Impedance 2 Ohms
JBL GTO527 5.25" Co-Axials - Impedance 2 Ohms

thanks
J

denim

Since you called the topic AMP, I am not sure if you are adding an amplifier to the system or referring to the small amp inside of the head unit.

If you are speaking of a separate amplifier from the head unit, there are plenty of 4 channel amplifiers that can run at 2ohms stereo. But as I am not familiar with that head unit and if you are connecting the speakers directly to the head unit, I am not sure the tiny amp inside can hold the load.

Honestly it would be worth it to spend a few more dollars, (especially if you are buying components) to grab a small 4 channel amplifier that will give true power to the components and be stable at 2 ohms stereo, and not put that load on the head unit with its ILS power (if lighting strikes). The extra money is worth it in quality in sound at the end of the day.

jamieh

Thanks Denim,

The AMP I'm refering is the head unit which has a MOSFET Power amplifier (50w x 4 Peak, 20w x 4 RMS).

I think the speakers, likely many now, are rate @ 2 Ohms but are recommend for 4 Ohms also.

The shop I'm buying from say its fine ???

I just thought I'd check with you guys.

denim

You have to be careful, because it is getting worse every year, shop owners or salesmen will say anything to get the equipment out the door. For the car audio market, as a whole, not that many smaller speakers are actually ratted at 2 ohms. Sub woofers on the other hand, can be ratted down to .5 or lower or up to 8 ohms. But still most car audio speakers (6.5" or smaller) are 3/4/8 ohms.

jamieh

Hi denim,

FYI

The speakers I'm purchasing are JBL GTO527, the following is taken from thier web site.

Power Handling, RMS 45 Watts
Power Handling, Peak 135 Watts
Frequency Response (±3dB) 70Hz - 21kHz
Sensitivity 91dB
Mounting Depth 2-5/16" (59mm)
Cut-Out Diameter 4-11/16" (120mm)
Impedance 2 Ohms

and includes the following info:-
True Four Ohm - All GTO Series speakers include reduced voice coil impedance designed to extract the most power possible from all amplifiers designed to drive loads of four ohms or less. In addition, many factory installed systems incorporate two-ohm speakers and include amplifiers designed to drive those loads. Replacing those reduced-impedance speakers with four-ohm models is hardly an upgrade, since the power output from the amplifier will be reduced. True Four Ohm addresses this as well.

denim

Not sure what you are getting at. That blurb seems to hint they are suggesting people should go with 2 ohm drivers to deal with impedance rise that can occur with most door speakers which are usually IB As in with the lowered air pressure behind the cone will cause the impedance to rise (meaning a 4 ohm speaker will actually only put 6ohms or less load on the amp) so if that is occurring a 2 ohm speaker will have impedance rise and show a true 4 ohm load to the amplifier. In addition they state factory installed, not after market.

jamieh

I think the point thier making is they work with a 4 Ohms system and existing 2 Ohm factory installed systems. From my reading Infinity make the same claim. Fingers crossed this setup suit my needs.

I'll be sure to check for excess heat generation with my new system and if I encounter a problem I'll be back on the the store striaght away.

I really appriciate you input.

thanks

LA TECH

As long as you do not overdrie your amp, you will be ok using the 2 ohm impedence speakers. However, as in home audio, poorly designed amps will become unstable into a very low impedence or shut down temporarily till internal temperatures stabilize. Enjoy your system and do not worry too much!

pazuzzu

the amps in head units arent the sturdiest on earth. the major concern with lower impedances is heat generation. your amp has to work twice as hard....the head unit is already in a very confined position. heat kills...

also...lower impedance generally increases your noise. not quite by an order of magnitude, but it's up there.

an alternative is since your amp is 20w x 4...just use two channels and wire the 5.25s and 6.5s in series. that will present a 4ohm load to each channel. you'll lose fader control but thats it.

but as was said with mids and tweets being infinite baffle, the actual impedance changes dynamically. mids/tweets arent going to overload the amp if you dont go crazy on the gains. BUT putting a 2ohm speaker into all 4 channels of an amp designed for 4/8 isnt treating it very nicely.

do it temporarily and grab an amp off ebay sometime? there's some seriously nice amps for cheap and the sound quality will be a LOT better with a real dedicated amp. some of the old phoenix gold stuff is CHEAP and they were really works of art. i sold one of my 500wrms M100s for like $175

06c230hwd

pazuzzu makes some good points man!
i cant imagine that you are too much of an audio buff and you must not be too worried about loudness and power.. so i would suggest running the coax's in series that way you give them a 4-ohm load as aforementioned by paz. which leads me back to my original point, an audio buff may be worried about losing fading controls, but it doesnt seem like you would be, so go for it!!!!! (and i only draw these conclusions from the fact that you are using the headunit to power the aftermarket speakers as oppossed to a seperate 400W 4 channel amp or something.)