Hi all,

I just spent the better part of Saturday (almost 14 hours from start to finish!) installing a Dynaudio MC427 amp for the front speakers (Boston Rally's).

I had the JL Audio 500/5 driving everything before. I wired everything with the original wires but had to buy some more 4 gauge power cable, which I used to split the power from the original 4 gauge power cables by soldering it onto the original cable. Is this ok? I don't want to spend $30 on a fancy chunk of metal (distribution box).

Anyways, listening comparisons, with the JL 500/5, and the Rally's, I turned down the treble by 1db around 10khz with my Alpine's built in EQ adjustment so that the sound is listenable. Without this adjustment, it's too edgy!

After installing the McIntosh, I've found that I don't need to make this adjustment any more. It's close, I could go either way, but I'm listening with the EQ settings flat on my Alpine, and it isn't as edgy.

Another thing, the Mc seems less precise in imaging. With the JL audio, center images are centered! With the Mc, images are more diffuse, it's almost as if left/right signals are being mixed? Images seem bigger, and less precise. Not sure if this is a good thing or not, will need to do some more testing. Anyone know of a good car audio test CD? Does one exist? Anyways, installing the amp was pretty fun, a lot of work though!

- Tony

 

Tony,

The Mc should beat out the JL in SQ and imaging (not SPL) in pretty much all aspects. The channel seperation of the Mc is quite high in real world testing and in non hyped numbers. Can't really vouch for the JL as I haven't seen any real test results.

How do you have the Mc hooked up? What's your complete setup?

Percy

 

I'm having a similar problem with my JL 300/4 driving the MD100's - I find myself reducing the gain a dB or two around 8-10K to reduce the edginess. Can't tell yet if it's amp or tweeters. Sounds like amp though if you've gotten it to go away by swapping out the amp...

Your difference in imaging is probably a phasing difference between the JL and the MC. I would have expected the MC to yield better imaging. Sounds like Percy is onto it = need to check the rest of your system.

 

Hi,

The JL 500/5 is driving the sub and rear speakers, while the MC drives the front.

I have an Alpine head unit driving everything. Standard RCA and power and speaker cord hookups, except that power cord is one wire from amp and one wire from car's ground point split into two wires before the 2 amplifiers.

I've found that it "seems" like the left speaker is softer than the right speaker. Imaging is still there, it's just that images seem slightly shifted over to the right. Maybe my Mc has a softer channel? I have a Radio Shack SPL meter, and several test CDs, what's the best way to test this?

About the idea that it could be a phasing problem, maybe, what's the best way to test that?

Thanks all for your help! This is a lot of fun!

- Tony

 

This will not be a conclusive test, but will give you more info to work from: Try playing one sinewave at a time from your test disc, at a few different frequencies. For each one, crank the fader on your head unit all the way left or right. (For testing the front, turn the rear speakers off completely.) Use your SPL meter at a fixed distance, say 6" to 1 foot, from the main speaker driver that will be producing that frequency (for 500Hz, meter the midrange driver, for 8KHz, meter the tweeter, for example). Once you get a level, do the same thing for the opposite side by panning completely the other way with the fader. Make sure that you're metering at the exact same distance and relative location from the driver. Compare the results: they shouldn't vary by more than a dB or two - if they do, you have a problem. This is a relatively inexact test unless you get really scientific about it, so not really conclusive, especially since the head unit's fader may be a problem variable, but will start to show you what's up with your system.

 

Tony,

The imaging characteristic that you mention is actually one of the nasties of the GS interior. With the stock system (or even one with a good speaker swapout), the image will be slightly softer on the left side than it is on the right side. Dispersion angle is better on the right side since the sound isn't hitting the leg, unlike the left.

I'd highly doubt that there is anything wrong with the Mc. One possible guess is that the JL is playing the midrange frequencies at a more "boosted" level, most likely due to the design more than anything else. The Mc is more accurate on the frequency response (no peaks or valleys) and is more at ease in it's presentation. The tweeter "edginess" that you mentioned with the JL seems to verify this, though at a higher frequency.

Try playing around with the gains a little bit. You might get the nice balance you're looking for.

Percy