# JL XD vs HD amp



## beemarman (Apr 10, 2006)

Hi,

Currently got a JL Audio XD 600/1 driving my 10w7 sub. I have been offered a HD 750/1 amp and wondered if it would make that much of a difference if i upgrade to the HD amp.

What do you guys think? would i notice the difference if I upgrade from XD to HD amp?


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## kyheng (Jan 31, 2007)

Yes, you will..... As HD are JL's high end series whil XD are more on "entry" level... Just the output power will make some difference...


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## BlueAc (May 19, 2007)

Depending on the cost out of pocket I would do it. 

Sent from my PC36100 using Tapatalk


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## kvndoom (Nov 13, 2009)

the XD will give you 600 watts at 2 ohms at 14.4V. The HD will give you 750W at anywhere from 1.5-4 ohms, with as low a supply as 11V. The HD is also a full-range monoblock amp, if you ever want to build some sort of insane system. It's better in every conceivable way.


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## DS-21 (Apr 16, 2005)

kyheng said:


> Yes, you will..... As HD are JL's high end series whil XD are more on "entry" level... Just the output power will make some difference...


The output power is the only thing that will make a difference. The "high end" vs. "entry level" is just marketing claptrap.

And depending on how the sub is wired, the output difference may not be much. Using the numbers here, 600W vs. 750W, what does that buy? A whole 0.97dB greater output.

Now, a question: do you hear the sub doing anything untoward at high volumes? (Often people mistake amp clipping and over-excursion; with a Jello W7 what you're far more likely to hear is the former than the latter.) If you do, then that extra ~dB of headroom may in fact make an audible difference.

Also, if you just like the looks of the HD better or just want to know you're running "top of the line" gear, then go ahead. It certainly won't _hurt_ the system (assuming levels are properly matched to the system with both amps) to swap.


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## kyheng (Jan 31, 2007)

^This, I not that agree with you.... If XD and HD are using same material, then why the price gap are bigger? If your statement are right, then people that buying HD(especially the 750/1) are stupid..... 
For me, I judge the amp based on the internal temperature after certain period of play time, tested this on my HD750/1, it is still cool after punch hard for 30 minutes. 
When the amp are hot(or close to its thermal protect setpoint), it will have some difference on the output, it won't be obvious, unless you really listen to it....


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## Viejo Y Lento (Aug 31, 2011)

XD = 1% THD @ rated output
HD = 0.03% THD @ rated output

As stated above, the HD will deliver full rated power @ 1.5 to 4 ohms from 11 volts and up. The XD will only deliver full rated power with 14.4 volts.


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## JKashat (Nov 19, 2009)

I was running a 10W7 ProWedge with a HD750/1 and it was awesome. Do it!


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## DS-21 (Apr 16, 2005)

kyheng said:


> ^This, I not that agree with you.... If XD and HD are using same material, then why the price gap are bigger?


Positioning in the market, and the technology is different. Neither of us are privy to Jello's actual costs for each, but it's safe to assume that the licensed technology + regulated PS + bigger case makes the HD750/1 the more expensive amp for them to produce.

There are some circumstances where the HD750/1 will be considerably more powerful. Driving a low-impedance subwoofer is not one of them.



kyheng said:


> If your statement are right, then people that buying HD(especially the 750/1) are stupid.....


If they are doing so on the basis that they think it must be far superior to the XD, then yes, that may indeed be the case. 

People who buy fractionally more powerful amps in expectations of hearing massive differences or getting much more headroom are, generally, stupid. Or at least ignorant of the math involved. 

There's little a "600W" amp can't do that a "750W" amp can. Big headroom improvements require much greater jumps in output. For example, going from an XD600/1 to an HD1200/1.

However, often people have other reasons for picking one part over another part. For example, one wants to match her/his HD600/4 and is price insensitive.


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## thehatedguy (May 4, 2007)

One thing you have to take in consideration with the higher end JL amps- the Slash and the HDs, is the fact that they tend to put out more power into reactive loads rather than resistive loads. Their lower line amps do not do this.

So you have 600 from the xD into a resistive load and 750 from the HD into a resistive load...the HD would likely make another 100 or more watts into a reactive load on top of that. For example the 600/4s are rated at 150 a channel into channel but are closer to 225 a channel IRL.

Either one of them should push the snot out of that sub. If it's an evenish trade, I would trade up for it just for the extra bargaining room later on if you would want something else (why you would I dunno).


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## beemarman (Apr 10, 2006)

Thanks for all the responses. I have decided to go for the HD 750/1 and HD 600/4 to match.


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## kyheng (Jan 31, 2007)

Well, you will regret of the money spend... But that's before you install and listen how they perform... Once you listen to it, you won't regret on that money spent....


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## tintbox (Oct 25, 2008)

Good purchase.


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## DS-21 (Apr 16, 2005)

thehatedguy said:


> One thing you have to take in consideration with the higher end JL amps- the Slash and the HDs, is the fact that they tend to put out more power into reactive loads rather than resistive loads. Their lower line amps do not do this.


Do they? I've personally experienced that with the old 300/4, which into loudspeakers sounded like a much stronger amp than ~45x4 (8Ω) despite third-party measurements that proved Jello rated the amp appropriately and competently. But the HD600/4 and MHD900/5 I've owned (and sold) did not seem to offer the same "bonus" power into the same loads. I've no doubt they do put out more-or-less what JL says they do, because JL doesn't play the stupid "underrating" game that many others in car-fi do.



beemarman said:


> Thanks for all the responses. I have decided to go for the HD 750/1 and HD 600/4 to match.


They're certainly very nice amps. FWIW, I'd be running them if they fit where I want to put amps in my daily driver. 

If your front stage currently has a lot less power, that's where you'll probably find the biggest sonic benefit. And there's the aesthetic benefit of matching parts, of course.


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