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MS-8 plus JL Audio: XD(10.1ch) or HD(8.1ch) setup?

6K views 29 replies 7 participants last post by  quality_sound 
#1 · (Edited)
Guys,

I have an MS-8 based system which I am either: 1) adding another XD amp to, or 2) replacing 1x XD amp with 2x HD amps. Here are the basics (details in pics):

JL XD600/6+XD700/5


View attachment XD Series.pdf <--click for PDF diagram

3 way front stage
  • L/C/R (midrange/tweets- all 2 way - 75 watts X 6 channels @90dB/w/m@4 ohm) - using XD600/6
    XD700/5
  • L/R (midbass) 75w @89dB/w/m
  • Rears - 100w @87dB/w/m
  • SUB - 300w @4ohm (ID10D4v.3)
Considerations
  1. Very even power/SPL distribution (1.7dB between loudest and softest driver oat above rated power)
  2. Fully active - tweets all have own channel (except rear coax)
  3. Rainbow SLC passive crossovers designed to allow active biamping
  4. Messy

Looks kinda like this but worse (amps will have to be stacked, no access to bottom one)


JL HD900/5+HD600/4

View attachment HD Series.pdf <--click for PDF diagram

  • L/C/R (midrange/tweets - all 1 way - 150watts x 3 @90dB/w/m) (uses 2 channels from HD600/4 for L/R and 2 channels (bridged) from HD900/5 for center
  • L/R midbass (150watts x2@89dB/w/m)
  • Rears (75watts x2 @87dB/w/m) <--Note less power to 2 ohm drivers due to HD switched "RIPS" power supply).
  • Uses mixed MS-8 + Amp Crossovers

Considerations
  1. More disparate power, 150 watts to each of front stage (more overhead room though, but 75 watts to rear. Sensitivity makes this a 6dB difference)
  2. Front Stage 1-way instead of two way, uses passive crossovers
  3. JL HD series are VERY nice amps, better S/N ratio
  4. Due to Mounting requirements will be much cleaner
Will look very similar to this (except MS-8 hidden)
 
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#2 ·
I thought you already had the HD amps...

If you ask me, I would say go for the HD set-up and never look back. No second guessing about power, headroom and SQ. PLD between the mids and tweets is not an issue, so going active is not really an advantage. Plus, you know that if you went with the XD amps, sooner or later the upgrade bug could bite you in the ass and then it would have been better to just go with the HDs from the beginning...
 
#3 ·
The power numbers aren't that much of a big deal. Its a 3dB difference in RMS power but the peak power difference actually isn't that much due to bi-amping advantage. In other words, the peak overhead is there on the 75 watts as well. The Rainbow drivers are only rated to 80w anyhow.

The PLD isn't the reason to biamp (Time alignment/Ms-8 channel assignment) will be identical in each setup.

In terms of strict power balance, I pretty much love the XD setup, but I'm mentally committed to the HD setup...but I am wondering if its entirely due to cosmetics...Tough choices! I can't believe I didn't think of this allocation before.
 
#4 ·
I like both set ups but I am partial to the HD for power and aesthetics.
The value of the visual effect can carry a lot of weight in terms of overall satisfaction once the build is complete. So go with the HD's :)
 
#5 ·
I'm the kind of person that loves high-end but in your case, I would go with the XD:
XD600/6 - L/C/R like you suggested
XD700/5 - front channels bridged to midbass
MS-8 - internal amp for rears

Rears really don't need much power and your midbass will love the extra headroom...

Kelvin
 
#7 ·
Thanks,

I've found from my trial and error that the MS-8 give much much better results with level matching on the drivers. If I do this with some drivers on MS-8 internal power, I might as well not have power on the other channels. I run the XD600/6 to my front stage right now (except center) and i get much better results with the gain turned down. The SQ is pretty near amazing but I bet I would not get much less volume if I deleted the XD600/6 due to the fact that the system is level matched. Thus, this is the reason I decided to amp all my channels.
 
#6 ·
I'd do the HDs because you don't NEED power balance. The rears are going to be turned down anyway so why waste the amp power? Also, since you can't access the top of the amp stacked on the bottom it'll be a pain to adjust. With front mounted controls setup will be a lot easier.
 
#8 ·
Though they won't be playing much due to Logic7, the won't really be "turned down"

Yes indeed, the front mounted controls are a godsend.
 
#9 ·
I've ran the XD700/5 (on MS-8) and the HD900/5 & HD600/4. I usually don't run rears at all, but definitely saw their benefit when running the MS-8 w/Logic 7. I tend to agree w/Quality Sound on not needing power balance and with Subwoofery on using the internal MS-8 to power the rears.

I would run the HD's, but run 150 x 4 (L & R, 2-way active on 600/4), 150 x 2 (Center, 2-way active on 900/5), 150 x 2 (Midbass on 900/5), 500 x 1 (Sub on 900/5), and rears on MS-8 internal amp.

All 8 front drivers getting their own 150W channel, 500W on sub, plus rears on MS-8?......This wins!:)
 
#12 ·
I'd probably go HDs in your case. However, I found that the rears amped at 75W with L7 turned on actually gave me an increase in midbass output, or so it seemed. My rears were playing pretty loud and down to 70 Hz or so, but the soundstage was still up front where it belonged. I kinda miss that setup now... If you like loud, dynamic music, as i do, amp the rears even just as an experiment, and see how you like it.
Neil, this is because Midbass is being played out of phase from the rears, to anchor it up front...from what I understand. Thus imaging should be IMPROVED with more power to the rears.
 
#10 ·
I'd probably go HDs in your case. However, I found that the rears amped at 75W with L7 turned on actually gave me an increase in midbass output, or so it seemed. My rears were playing pretty loud and down to 70 Hz or so, but the soundstage was still up front where it belonged. I kinda miss that setup now... If you like loud, dynamic music, as i do, amp the rears even just as an experiment, and see how you like it.
 
#11 ·
No matter which way I slice it; my overall system power is going to be limited by my least powerful driver in terms of SPL. Either the MS-8 will level match the stronger channels to that driver, or (as I have found), you get AMAZINGLY BETTER RESULTS by turning down power to match all channels within a few dB.

There is no way I am giving only 30w to the rears. That is the whole reason for this project...to power them! (and more importantly the center).

In other words, it does no good to give my front stage drivers a gagillion watts of power when I have to dial that back down (or let MS-8 do it) to match the 30w that the rears are getting.

Have you other MS-8 users not noticed this? or is my experience different?
 
#14 ·
My rears and sides are on MS-8 power. Since they are run in parallel (1 ohm per channel), they are very loud. During level matching, I had to bring up all other channels to match the rears (amps set to 2V initially). Power to the rears I have found does not matter much, since they are HEAVILY attenuated during normal listening with L7 turned on. In my and Taibanl's case, the rears are 4" so they don't contribute to midbass, plus we have 8s under the seats.
 
#15 ·
Exactly... Apples to oranges. I had well-sealed 6x9's with a few cu.ft. in the back with the crossover set much lower. That means they'd take more power than a set of 4's that were crossed high. I think Logic7 sounds much better with the rears playing as low as it will allow, with considerable power for dynamic transients. I'm not an SQ purist, I listen to certain types of music music very loud, and having the rear speakers assist the front in the midbass department while not screwing the stage up is pure bliss.. Crazy amounts of visceral energy that kicks you in the chest. Kind if reminds me of Patrick Bateman's epic midbass array thread.
 
#20 ·
I am loving the attention this thread is being given..thanks guys! First world problems :-/
 
#21 ·
OK... the rears in L7 play loudly or not so loudly depending on what information in the track gets steered to the rear. On some tracks, there won't be much output on others, there may be a lot. Ideally, the rears would be able to play as loudly as the fronts for those times when the recording dictates that they should, but this isn't super critical.

When MS-8 does the calibration, it looks for the rears to be about as loud as the fronts--it level matches them. If you amplify the front and not the back, MS-8 will reduce the level of the fronts. That means that if you've paid for 1000 watts for each of the front speakers and don't want to buy an amp for the rears, you won't experience Logic7 as it's supposed to be experienced.
This is why...
 
#23 ·
Exactly. If you listen to electronic music, you'd be very suprised how much information is purposely mixed exactly 180 degrees out-of-phase. Listen to Rusko - Hold On with L7, I could go through and pick out a few others. You need some headroom back there, all the way down to 70 Hz or so, it will get all distorted and flattened.
 
#29 ·
So do people agree more SQ out of 150x5 HD powered front stage than 75x8 XD powered / biamped front stage?
 
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