It might be, that DR Vtwin is allowing for the vender that sold you your speakers, to help you. The speakers with the Amp, at least to me, sound really good. I had the hog tunes Ulta system previously. At first, I set up my system with the J&M amp powering the front speakers and using the head unit to power the rear ( hog tunes)speakers. I ended up disconnecting the rear speakers, because they started distorting at the higher volumes. It's going to be difficult to get a lot of bass from any fairing speaker, but I do feel these are an improvement over what I had. For bass, they are better than what I expected, but my expectations were low going in.

The foam they supply, for under the fairing, does help some. Did you instal it? I didn't think it would make a difference, but it did. I think you will be much happier, once you instal the new amp.

I've purchased from AMC a few times. They offer really good prices, but you need to be sure you're ready to wait a while for your product & know going in, that you're not going to get much service & support from them.

I am surprised that the J&M guy here hasn't contacted you to try and help.

 

I bought some J&M stuff last week but haven't installed it yet. Either way I think I will be happy as long as they are better than the Booms because I got my 7.25's for $199.00 shipped.

 

Guess it wasn't just me when I thought the J&M's didn't sound any better than my Booms.

 

My vendor told me tough luck. No return. I returned the wrongs ones they sent on my tab and they have yet to repay me. I've had nothing but troubles out of these guys. Now they say tough luck.

I have the foam pad installed.

I know the issue and Dr V-twin is avoiding answering it. JMJohn has not been in either thread so I can't comment. Dr W-twin was in the other thread where I pointed this out and asked specifically and he chooses not to answer now.

You guys need to understand how this ohm thing works.

4-ohm HU(headunit/radio) + 2 ohm speakers + double output from that headunit. Flip it around and it gets half. Not exactly but you get the idea.

Listen, amps multiply signals, that their basic job...simple terms.

With the factory HU(harmon) they are using a low level input to the amp. That is a 2-ohm HU. Using a aftermarket HU(sony) you use the RCA output and that is a low level output at 4-ohms.....major voltage difference there. You starting off with half the input signal strength.

I'm asking specifically if they know this is the issue with crappy sound from the 7.25's and the amp using a different headunit.

 

shore

Seems to be a fair question. Have you tried a pm to JMJohn?

JW

 

I feel your pain Shore but the 2 ohm vs 4 ohm issue is not really a J&M "problem" is it? With any radio system it's up to the Buyer to purchase products that match their application. If J&M stated in their brochure that their speakers output the same level of audio using your Sony unit I would complain, but it seems they don't. However the most common complaint when running a mismatched circuit would be "lack of power", but as you already identified....you are running a 2 ohm speaker on a 4 ohm circuit. So you are actually tasking the Sony radio to ouput twice the output power it's supposedly capable of. If stable, you should be getting more power (audio) out of your setup than someone running a matching impedance HK unit. Twice as much thereabouts. That is if your radio's amp is 2 Ohm stable and does not fry first. Point is you should be hearing big audio already without an External amp.

Also, low voltage, high voltage, line-level inputs/outputs in reference to an Amp is not proportional or related to final output level of the Amp to the speakers. Low level line inputs/outputs are measured in "volts" not ohms. Here a External Amp has only to take a sample of the radios Output signal and then amplify it. The level of which it takes that sample doesn't matter since it's just a sample/reference. When using High level inputs, again the amp only takes a sample of the signal for reference and whatever level that sample is taken at does not affect the output level of the External Amp. It's just an input. As you know, you typically use low level inputs when you have RCAs which is actually a bypass of the radio's internal amp, and High Level inputs when you don't have RCAs. So when you hook up your external amp, use whatever inputs you have access to, and then wire the Amp output for a 2 ohm load on the speaker side and you should be good and getting the amps full rated power to the speakers.

Something like that.

Anyway, I echo what you're saying about the speakers though. I don't think they are worth 230 something bucks. I've heard them at the J&M booth many times and they are "ok". My ears I suspect. I would try a different speaker just like it seems you are about to do, and put the J&Ms on the For-Sale forum.

lp

 

I pretty much said what you did without getting into the difference between volts and ohms. I even said it's not even even, just that's the way it works. You use a 8-ohm speaker on a 4-ohm deck it's gonna get very little power...vs using a 2-ohm speaker on a 4-ohm deck, which would get more than the rated. That's where I'm at and it has no bass.....matter of fact, I just rode for 2 hrs in town with the iphone hooked up and all I heard was highs.

Now everything goes back to norms when I add the amp, in guessing. I was up ohms/output and now I will go down ohms and add the watts from the amp. If you can follow that. Maybe that will even it out and add some low-end. I highly doubt it. I'm going to have to sell these things and get some good 6.5's.

The amount level input absolutely affects the output of the amp. The difference between a 2v pre-out and 5 volt pre out is night and day.


Regardless, I asked them on the phone what works with my sony headunit and they said the 2-ohm, well it sounds like ****.

whose fault is it now? ACM originally, told me to run the 8-ohm...holy cow.

 

Yeah I think we've said the same thing with the exception of the line levels. Your 2 Volts to 5 Volts range point is true however I was talking about 2/4/8 ohm high level inputs. It's not going to matter to the Amp. You are still sending 40 something watts of power down the front end input of the Amp. Way more than enough to grab the signal for amplification.

Yes, I think you'll get the output power you expect from the Amp no matter if the Radio is 4 ohm and the Speakers are 2 Ohm. The External Amp doesn't care.

No, I don't think the Amp is going to make any difference in the Bass response of those speakers.

ACM must be crazy....

Good luck to you Sir. I'm sure you'll get your money back out of them though, so no worries.

lp

 

I just got an email back from J&M tech and they said the aftermarket HU with 7.25's and the amp will sound just the same as the stock HK.

I guess we'll see. Amp should be here in a couple days. I'm running 8ga power/ground and 100amp fuse. Not my 1st rodeo.

 

FromShore...
>>You guys need to understand how this ohm thing works.
>4-ohm HU(headunit/radio) + 2 ohm speakers + double output from that headunit. Flip it >around and it gets half. Not exactly but you get the idea.

Shore...given your experience with the 2 ohm speakers and your Sony HU, would you have predicted better results with the 8 ohm version? I have that setup on my FLHT w/Biketronics Sony HU 4 ohm and I guess it sounds OK to me, including running Pandora through my Droid...but then it's been friggin' winter up here and haven't ridden in a while.