(Sort of) Finished my little stereo build...

Interesting finding. Adding gain is adding gain, doesn't matter where it occurs. I would have thought, perhaps naively, that since this is occurring on the analog side of things that introducing another device in the chain would be worse (although perhaps below audible) than a simple pot adjustment on the amp gains. This also assumes the gain is not capable of or, is not manually set to, such a level that the dynamic range is impacted.

I am running an XD 600/6, 4 into 2 for my midbass, and 2 straight for the tweeters, gains set by O-scope, and am not finding any distortion issues. Maybe the XD isn't in the same "class" as the Hertz amps, but there's no audible distortion due to the amp (for comparison previous amp was an old school Pioneer Premier PRS series).

Hope that expressed my questions???

 

With the JL XD amplifier, I originally did not set the gain structure with an oscilloscope, only by ear. While listening, I noticed a lot of distortion especially with certain instruments and vocals. After hearing this, I reset the gain structure with an oscilloscope at -5db and found that putting the gains past 25% on those amps added clipping to the signal and distorted the sine waves seen on the scope. The sine waves looked like shark fins on the scope where I had the gains set previously (about 50% for the mid-bass, 30% for the tweet). After setting the gains to where there was no apparent distortion (used 100hz, 400hz, 1khz, 4khz for the mid bass channels and 4khz, 8khz for the tweeter channels), the levels were unsatisfactory. After that is when I made the decision to put in the Class AB Hertz amplifiers. At first, I did add gain to the mid-bass amplifier using a scope. The signal was loud and clear, but made smoke pour out of my mid-bass speakers. Everything sounded great, but it was just too much power for the little 6.5" Mille. After blowing a few mid-bass speakers and swapping them out under warranty, I reset my gain structure a little more conservatively with 0db tones.

 

For the same reasoning, I was also a little skeptical about adding the line driver when my boss had suggested it. I've learned not to second guess him, though. He really knows his shit. Sure enough, the audio control piece was a great addition. On the scope, everything looks smooth and the dynamic range of the system is very impressive. Of course, now I just have a pet peeve against adding gain to amplifiers.

I'm not saying the JL XD's are bad amplifiers, they just couldn't give me the levels I was looking for without compromising the signal. If I were to put together a system for a good friend or family member, JL XD would most likely be my first choice.

Edit:
Also, I'm sure the increase in power has a lot to do with my judgement between the two amplifier setups. Comparing < 300 watts per side to ~510 watts per side is apples to oranges.

 

It's always a hard call to A-B judge systems.

That said, the gains on the XD should have been set for ~180 watts (bridged) so if you were driving to around 300 then it's easier to understand why the signal got distorted.

I didn't realize the Hertz speakers were so power demanding. I've read the same thing about the Alpine shallow subs -- really need twice their rated power to produce.

 

Oops, I didn't mean 300 watts per side mid-bass only, nor was I referring to a definite measurement of wattage. Only what the amp is "capable" of producing.

The only time I've actually measured and calculated wattage was with the EP4X bridged which was around 270 watts per mid-bass speaker at 100hz, 0db.

Its not that they are really, THAT demanding. I've heard the same Mille speakers played in bi-amplified setups with 180w to each mid, and 180w to each tweet. After tuning, they sounded amazing and there was really nothing to complain about with the volume. I just like to listen to music violently loud and I have very high expectations for sound quality.

 

Subs you shouldn't need a c(r)ap after the alt and batteries do the big 3 and see if that helps whatever problems you may be having.

 

I'm interested in those tweeter pods. think you could make another set?

 

sure. what tweeter did you have in mind? pm me about it

 

pm sent

 

Fantastic work!

 

yahhhh guy.